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ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
ThefocusisonsoilecologywhichconsidersPopulationdynamicsoHowdifferentorganismtypesrelate toeachotherandtheirenvironmento
•
Definitions
Community:Agroupofinteractingpopulations•Population:Anassemblageofanorganismtypeinanarea•Habitat:Placeoccupiedbyanorganismtype,populationorcommunity•
EachorganismtypeoccupiesaparticularecologicalnicheTheroleanorganismtypeplaysinitsenvironmentoie.:itsfunctionandplaceintheecosystemo
•
Anicheisaspecificsetofcircumstancesforanorganismtypeandisdefinedby:ThetypeoffooditconsumesoItspredatorsoPhysicalconstraints
Temperature,light,moisture§o
ChemicalconstraintspH,redoxconditions,nutrientrequirements,toxiceffects§
o
•
Anoverlappingofconditionsresultsincompetition•
GroupsofSoilOrganisms•
HigherPlants(PlantKingdom)Provideareserveoffood(nutrients)andenergyforotherorganismsbyphotosynthesis
CO2+H2O→CH2O+O2§
o
EnergyforthereactionisprovidedbylightLight+2H2O→Energy+4H++O2§
o
ChlorophyllcatalyzestheconversionoflightenergytochemicalenergyoPhotosynthesisisthebasisoflifeonearthasweknowit
Mostorganismsdependonitdirectlyorindirectly○Responsibleforaerobicconditions(atmosphericO2@21%)andlowatmosphericCO2
○
http://www.geocraft.com/WVFossils/Carboniferous_climate.html○
o
GreenplantsareautotrophsOrganismsthatdonotneedorganicenergysubstrates○
○
ie.:theydonotoxidizeorganicmatterfortheirenergyrequirements○ProduceorganictissuesfromCO2andionsusinglightastheenergysource○
•
PlantsprovideorganicmattertosoilsintheformofrootsandlitterIntegralpartofthecarboncycle○
•
SmallAnimals(AnimalKingdom)Helminths,annelids,mollusks,arthropods(pp.143)oAnimalsareheterotrophs
Carbonandnutrientsareassimilatedandenergyrequirementsaremetbyrespiration
○
Aerobicrespirationisrepresentedby:○CH2O+O2→CO2+H2O+Energy○
o
•
CarbonCycleThisisthecyclingofcarbonfromorganictoinorganicformsandbackagainoInvolvesautotrophsandheterotrophs(animalsandmicrobes)alongwithchangingenvironmentalconditions
o
PhotosynthesisCO2+H2O→CH2O+O2§
o
(Aerobic)RespirationCH2O+O2→CO2+H2O§
o
TheCO2canbe:Returnedtotheatmosphere§Incorporatedintosoilmoistureandgroundwater§
CO2+H2O→H2CO3§H2CO3→H++HCO3–§HCO3-→H++CO3=
HCO3–andCO3=canbeprecipitatedasmineralsØ~99%ofallcarbononearthisboundincarbonateminerals
SomeasfossilfuelsoØ
§
o
•
MicrobesProtozoa,somealgae,somefungi,bacteria
Includes:§KingdomProtista§KingdomMonera§
o•
KingdomProtistaGroupintowhichallunicellulareukaryotescanbeplacedoProtozoa,unicellularalgae,unicellularfungioEukaryotes:
Organismshavingadistinctnuclearmembrane§o
Protozoa:Unicellular(oracellular)@~8µm§Foundinmoistsoilsandaquaticenvironments
Dormantotherwiseascystsandsporesا
Waterisneededfortheirmobilityandforthatoftheirfood§Reproducebybinaryfission§Lifestyles
ActivepredatorsOfbacteriao
Ø
ScavengersOfparticulateorganicmattero
Ø
SaprophytesAbsorbdeadorganicmatterinthedissolvedformo
Ø
ParasitesNobenefittohosto
Ø
§
ExamplesAmoebaØCiliatesØFlagellatesØ(Giardia)Ø(Cryptosporidium)Ø
§
o
AlgaeSimpleplantsthatcontainchlorophyll§Liveonmoistsoil(andaquaticenvironments)§
o
•
FungiHeterotrophs
DestroyorganicmatterØDeriveenergybyoxidationoforganicmatterØ
§
Singlecelledormulticellular§Enjoymoistconditionsonland§Lifestyles
AllaresaprophytesØSomeparasiticØSomesymbioticØ
§
ExamplesMushroomsØMoldØYeastØ
§
o
MicorrhizaeSymbioticrelationshipbetweenplantrootsandfungi
PlantProvidesfoodforthefunguso
Ø
FungusProvidesplantwithinorganicnutrientsbyextendingtheirhyphae(filamants)anddeliveringnutrientstotheplant
oØ
§o
KingdomMonera(Bacteria)Allaresinglecelledprokaryotes
5– 5µm§Canbe~100million/gramoffertiletopsoil§
o
FoundeverywhereinthebiosphereoExtremelydiversephysiologicallyoVeryprolific
Candividebybinaryfissioneveryfewhours§o
Veryadaptabletochangingphysical,chemicalandnutrientconditionsasfarastheirtypesandnumbersareconcerned
Godormantascystsorsporesinbadtimes§Opportunistic
Takeadvantageoffavourableconditionsا
o
Spreadquicklybydust,waterandotherorganismso
•
BacteriacanbeidentifiedbyvariouswaysGram’sstainoShape
Rod,spirillum,coccus,filiments§o
BygrowthusingspecificnutrientbrothsandtemperatureoWhattheyuseasanenergysource
Organicmatter§Inorganicmatter§Light§
o
WhetherornottheyrequirefreemolecularoxygenforrespirationAerobic§Anaerobic§Facultative§
o
•
RespirationOrganicsubstancesarebrokendown(oxidized)intosimplerproductswithreleaseofenergy
o
Thisenergyisincorporatedintoenergycarryingmolecules(ATP)usedformetabolicpurposes
ATPhashighenergyphosphatebonds§Incells/musclesitishydrolyzedtoADPtoreleaseenergy§
o
•
AerobicrespirationOrganicsareoxidizedusingfreeO2
Carbohydrate+O2→ CO2+H2O+Energy§o
•
AnaerobicrespirtaionNO3-,SO4=andCH2Ocanbeusedasoxidantscorrespondingto:
Increasinglyreducingconditions§Changeinpopulationtypes§Slowerratesofdecay§
o•
FermentationSpecialcaseofanaerobicrespirationoSomeoftheorganicsubstrateitselfisusedastheoxidizingagentandisreducedtoacids,alcoholandmethane
o
Carbohydrate→ CO2+Acids/Alcohol/Methane+EnergyØ
o
•
RoleofBacteriainSoils
Largelyresponsiblefordecompositionoforganicmatter(incombowithfungi)Absorbdissolvedorganics§Canuseenzymestofacilitatedissolution§
o
MostlyheterotrophsAerobic,anaerobic,facultativeanaerobic§
o
SomeareautotrophsBlue-greenalgae§
o
Somearechemautotrophs(lithotrophs)Importantrewaterchemistry§
o
ImportantrenutrientcyclingoContributetohumusproductionoImportantinbioremediation
Converttoxicmaterialstonon-toxicbyproducts§o
SomeareparasitesoSomearesymbiotic
Nfixers§Assistindigestioninthegutofotherorganisms§
o
•
DecompositionofOrganicMatter•
AfunctionofheterotrophsoMostimportantgroupsaremicrobes
Especiallybacteriaandfungi§LikeDOM§Useenzymestohelpdissolveorganicsolids§
o
Deadanddyingorganicmaterialisrapidlycolonizedbyfastgrowing,opportunisticbacteria
Soluble,easilydegradedcellularconstituentsareattackedfirst§
o
Moreresistant,complex,insolublematerial takesmoretimeBreakdownofthismaterialishelpedbyanimalssuchasinsects,bugsandworms
§
Theychewitupandpartiallydigestitresultinginprogressivelysimplercompoundsthatcanbeusedbysimplerorganisms
BacteriaintheirguthelpØ
§
o
Wood(celluloseandlignin)isattackedbyaveryspecializedseriesoffungiUsespecificenzymestodissolvematter§
o
Eventuallyablack,amorphous,resistanthumusformsandtheprocessslowsoHeatisreleasedcorrespondingtoalargereductioninmass
ConvertedtoCO2§Someorganicelementsareconvertedtonewbiomass§Somereleasedintosolutionasorganicandinorganicsolutes§
o
Ratesofdecay(andorganismsinvolved)atanypointdependonThenatureofthematerial§Stageofdecay§Environmentalfactors§Nutrientsupply§
o
NatureofmaterialDecayisretardedifthematerialis:
InlargepiecesLowersurfaceareaØHardertoingestØ
§
DenseandnonporousLessaccessibletomicrobes,water,nutrientsandO2Ø
§
ResistantNon-soluble,complex,highmolecularweightØ
§
o
Itistheroleofanimalstochewandpartiallydigestmaterialtomakeitmoreporousandsimpler
o
•
StageofDecayDecayisrapidatfirstanddiminisheswithtimeoSolublecell constituentsareattackedfirst
Resultsinaresidueofinsoluble,resistantmaterial§o
•
EnvironmentalFactorsPhysical
TemperatureCanchangewidelyatsurfaceØOptimum@35oC
35oCtendstokill•Ø
Temperaturesclosetofreezingwill~stopgrowthbutnotkillØ
§
MoisturecontentLowerlevels
Reducesmobilityofmicrobes,foodandnutrientsoLeadstoinsolubilityoCaninitiatedormancyo
ا
DesiccationmaybeavoidedbyOsmoticregulationØHidinginsideaggregatesØ
§
SaturationResultofpoordrainageandcompactionØLeadstoanaerobicconditionsandslowdecayratesØAnaerobicformslurkinsideaggregatesreadytotakeoverØ
§
o
ChemicalEnvironmentpHtoohigh/toolow
DirecteffectonmetabolismØResultsintoxiclevelsofsomeelementsØ
§
HighersalinityCancausedesiccationØ
§
RedoxconditionsAffectsdominantpopulationsandspeedofdecayØ
§
o
NutritionalConstraintsCandNaremostcommonlylimitingforbacteria§Deficiencyoftensuchthattheelementsarepresentinthewrongform
Tendtobeboundupinlarge,organicmoleculesØSoluble,inorganicformsareneeded
NH4+andNO3-arefavouredformsofNoCdeficiency
Lackofreadilydecomposableorganicmatter§o
Animalsfacilitatebreakdownofresistantmattermakingnutrientsmoreaccessible
o
Ø
§
o
•
SoilBiologyJanuary6,2016 10:26PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
o
Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
o
Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
o
Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
o
GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
o
IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
o
ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
o
Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
○
Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
o
Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
§
Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
§
o
ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
Mostgroundwaterstartsasrainorsnowthatinfiltratessoilandmakesitswayintotheunderlyingearthmaterial
•
Soilzoneprocessescanhavealargeeffectonwaterchemicalquality•Manyprocessesmaycontinuetoaffectgroundwaterasitmakesitswayfromrechargetodischargeareasindifferenthydrogeologicsettings
•
AtmosphericEffects•
RainwaterisaverydilutesolutionbutitisnotpureRaincontainsmanydissolvedgasesandsolids§
o
AtmosphericaerosolsContributedissolvedsolidstorain§Smallparticlesofsolidsorliquidsranginginsizefromafewmoleculesupto~40μ
§
Mostendupinrainsincetheyactascloudcondensationnuclei(CCN)§
o
AtmosphericwatervapouralwayscondensesonaparticleornucleusoCondensationoccurspreferentiallyon
Largeparticles§Solubleparticles§
o
Dropletsgrowinsizebycollisionandcohesiontothepointwheretheyfalloutasrain
o
Particlesintheatmospherereturntotheearth’ssurfacebyRainout
ThoseservingasCCNandaffectingrainchemistry•§
WashoutTheflushingoutofparticlesbyfallingraindrops•
§
(Dry)FalloutParticles>~40μ•
§
o
OriginandCompositionofAtmosphericAerosols•
Twomaintypes:Primaryparticles§Secondaryparticles§
o
PrimaryparticlesEmitteddirectlyintotheatmosphereassolids§Tendtobelarger (>1μ)§
o
Examples:oSeasaltcrystals
Fromwaterdropletspropelledintotheairbyburstingbubblesattheoceansurface
§
2– 20μ diameter§Reflectthechemicalcompositionofseawaterwith~55%Cl- and~28%Na+
§
o
DustSilica,mica,clays,ironoxides§ContributeAl,Fe,Si,Ca,K,Na,Mg§
o
SmokeFineparticlesoforganiccarbonwithaccessoryelements§Biomassburning§
o
FuelcombustionAsh§Soot§
o
VolcanismSilicatemineralparticles§
o
SecondaryparticlesFormedfromgaseousemissionsthatsubsequentlycondenseintheatmosphere
§
Oxidationofgaseslessensvolatilitycontributingtoaerosoldevelopment§Tendtoformsmalleraerosols<1μ§
o
Examples:Volatileorganiccompounds(VOC’s)
Metabolicby-productsofvegetation•Organicmatterdecomposition•
§
SulfateaerosolsfromgaseousprecursorsSO2
Fuel(coal)combustionoVolcanismo
•§
BiogenicDMS(di-methylsulfide,S(CH3)2)Fromplanktonmetabolismandbiologicaldecay•
§
Resultinsulfate(SO4=)aerosolsbyoxidationintheatmosphere2SO2 +O2+2H2O→4H+ +2SO4=•
§
o
RainWaterChemistry•
TDSVerydilute§Lowerinremote,continentalareas§Higherinmaritimeareasandareasaffectedbyindustrial/urbanactivity§
o
pHAslowas4- 5fromacidraineffects
SulfuricacidfromburningofpyriticcoalandcrudeoilS+O2→SO2o2SO2 +O2+2H2O→4H+ +2SO4=o
•
Nitricacidfromvehicleemissions4NO2+O2+2H2O→4H++4NO3-o
•
pHis@5.5– 5.7forraininequilibriumwithatmosphericCO2 andintheabsenceofacidraineffects
H2O+CO2→H2CO3o
•
§o
SummaryofRainSolutionChemistry•
Rainwateris:Verydilute§Slightlytomoderatelyacidic§Oxidizing§
o
Hence:chemicallyactiveinpromotionofsoilzoneprocesses
SoilZoneEffects
o
AlmostallwaterthatentersagroundwaterzonepassesthroughasoillayerThiscanexertalargeinfluenceonwaterchemistry§
o
Significantly:LargeamountsofacidcanbegeneratedaffectingpH§Concurrently,allormuchofthedissolvedoxygenmaybeconsumedaffectingtheoxidation-reductionpotential(ORP)
§
o
TypesofAcidsGeneratedinSoils
CarbonicAcidAresultofoxidativeprocessesinvolvingrespirationandconsequentcarbonationofwater
Importantly:microbesandrootsCH2O+O2→CO2 +H2O□CO2 +H2O→H2CO3□
§
○
BiologicallyactivesoilsresultinmuchhigherCO2 contentinporespacesCanbe10– 100’softimesatmosphericconcentrationswitharangeinpartialpressuresfrom10-3 to10-1bar
§
SoilmoisturepHcandropsignificantlyAPCO2of10-1 canresultinapHof~4.5dependingontemperature
□§
○
CO2 concentrationsarevariableinspaceandtimeandareaffectedby:Temperature
AffectsbiologicalactivityandCO2 dissolution□§
○
MoisturecontentAffects:
Biologicalactivity□GenerationofH2CO3□CO2 diffusionoutofthesoil□
§○
SoilproductivityAffectstypeandamountoforganicmatter,plantgrowthandmicrobialactivity
§○
SoilPermeabilityAffectedbysoiltextureandstructure§Affectsgasdiffusion
O2 intosoil□CO2 outofsoil□
§
○
IntermittentpulsesofH2CO3 aregeneratedatrainfallevents○H2CO3 encountersmineralsthatreactwiththeacidcontributingtoweatheringreactions,theformationofnewmineralsandsolutiondevelopment
○
H2CO3canbeconsumedwhileatthesametimebereplenishedbyongoingrespiration
○
o
MineralAcidsMineralacidsarearesultaerobicbacteria-drivenoxidationofinorganicmaterial
○
SulfuricAcidOxidationofsulfideinsulfide-bearingmineralssuchaspyrite(FeS2),arsenopyrite,chalcopyrite,sphalerite,pyrrhotite(FeS)
§
Calledacidrockdrainage§FeS2 +15/4O2+7/2H2O→ Fe(OH)3+4H++2SO4=
eg.:ByThiobacillusferrooxidans□§
○
NitricAcidAmmoniumfromorganicmatterdecay,fertilizersetc.isoxidized
NH4++2O2→2H++NO3-+H2O□§
Referredtoasnitrification§
○
OrganicAcidsDerivedfromdecayoforganicmatter§eg.:humicandfulvicacids§
○
Weakacids○
o
ElectrochemicalEvolutionSequence•
Thisrelatestothetendencyfortheredoxpotentialtodecreaseaswatermovesalongitsflowpathfromtherechargearea
Thiscanbeasignificantsoilzoneeffect§
o
Raininitiallyhasahighredoxpotentialof~750mVduetoexposuretoatmosphericoxygen
OxidationoforganicandinorganicmatterinthesoilzonecanremovemuchoftheDOandtheORPdrops
§
o
ByhowmuchtheORPdeclinesbeforewaterreachesthewatertabledependsonanumberoffactors
SoilproductivityTypeandamountoforganicmatter•Plantgrowth•Microbialactivity•
§
o
PresenceofoxidizableinorganicmatteroSoilpermeability
AffectsContacttimeofwater•Oxygendiffusionintosoil•
§o
SoilthicknessoDepthtowatertableoTemperature
AffectsBiologicalactivity(respiration)•Oxygendissolution•
§o
SoilmoisturecontentAffects:
Respirationrates•Oxygendiffusionintosoil•
§
ExamplesRechargeareaisclayey/silty
ShallowgroundwatermaynothavedetectableDO(<0.1mg/L)
o•
Rechargeareaissandy/gravellyShallowgroundwaterwillhavedetectableDOo
•
RechargeareahaslittleornosoilcoveroverfracturedbedrockDOisdetectablefaroutintothegroundwaterflowsystem
Little/noconsumption§Fastinfiltration§
o•
§
EvenatDOlevelsatorbelowdetectablelimits(~0.1mg/L)canbesufficienttodrivemanyimportantoxidationreactions
Importantconsequencesrethechemicalevolutionofgroundwater•
§
o
ImportantInorganicOxidation(andReduction)ReactionsinSoils
MajorAnionEvolutionSequence•
Salinityandmajorionconcentrationstendtoincreasealongagroundwaterflowpath
Thechemical characterofgroundwatertrendstowardthatofseawaterwithincreasing:
Distanceoftraveland/or§Contacttimewithgeologicmaterial§
○
o
ThistrendcanbereflectedintermsofthedominantanionpresentoWithconcentrationsinmeq/L:
HCO3-→SO4=→Cl-§o
TheanionevolutionsequencecanbecorrelatedwithIncreasingage(contacttime)anddistanceoftravel○IncreasingTDS○Flowfromrechargetodischargeareas○Increasingdepth○
o
WorksbestinthicksedimentarybasinsoHCO3- Stage
Representsyoungwaterneartherechargearea○Azoneofactiveflushing○HCO3- isderivedfromatmosphericandsoilzoneCO2
H2CO3→H++HCO3-§○
o
VeryfreshwaterwithlowTDSoTDSislimitedby:
Shortcontacttimeandtraveldistance○PCO2○PresenceofmineralssusceptibletoH2CO3○
o
SO4= StageoImportant~solublemineralsthatreleaseSO4=oGypsum(CaSO4 .2H2O)
K=10-4.6○o
Anhydrite(CaSO4)K=10-4.5○
o
GypsumandanhydriteareoftenpresentintraceamountssuchthatwaterhastotravelasignificantdistanceforSO4= todominate
Activeflushingintheshallowsubsurfacemayhavealreadyremovedthesemineralsbypriordissolution
○
o
Watermaybebrackisho
Lessactivecirculationinthiszoneo
Cl- StageoIndicatesoldwaterthathashadalongcontacttimeanddistanceoftravel
Cl-ispresentintraceamountsonlyintherockformingsilicateminerals○o
EvaporitedepositsarecommonatthebaseofdeepsedimentarybasinsHalite(NaCl)andsylvite(KCl)arecommonandverysoluble○Khalite =101.6○Ksylvite =100.9○
o
Maybedealingwithconnateorfossilwatero
CanbehighTDS(saline)watero
Verysluggishflowo
TheanionevolutionsequencecanhelpinterprettheflowhistoryofawaterPiperplotsareuseful○
o
Majorcontrolsontheanionevolutionsequenceare:Mineralavailability○Mineralsolubility○Scaleoftheflowsystem○Sequenceofcontactwithdifferentmineraltypes○
o
Theanionevolutionsequencemay:Occurasaslow,gradualchange○Occurindistinctsteps○Beshortcircuited○NotevolvebeyondtheHCO3- orSO4= stage○
o
AsimilarschemeforacationevolutionsequenceisnotfeasibleCationexchangecancauseabruptchangesorreversalsinanyprescribedsequence
○o
GroundwaterinCarbonateTerrain•
Thisisasummaryof:Howwaterchemistrychangesasitflowsthrough§rocksandsedimentscontainingcarbonateminerals§
o
ThecontrolsinvolvedoImportantmineralsinvolved
Calcite(CaCO3)§Dolomite(Ca,Mg(CO3)2)§
o
CarbonatesareverysusceptibletodissolutionbyacidsoCarbonatemineralsarewidespread:
Sedimentarysystems:Tills•Cementingagentinsedimentaryrock•Limestonebeds•
§
MetamorphicrockMarble•
§
IgneousrocksFracturefilling•
§
o
Importanceofcarbonatesinwaterchemistry:ControlspHandalkalinity§Contributesinorganiccarbon§
o
Thereare2carbonatedissolutionmodels:Opensystem§Closedsystem§
o
OpenSystemDissolution•
OccursabovethewatertableintheunsaturatedzoneCO2isabundantintheunsaturatedporespaces○PCO2 isconstantthroughout
Ongoingrespiration§Diffusionintheopenporespaces§
○
o
Hence,H2CO3 remainsconstantevenasitisbeingconsumed
"#$% = (∝ )%#$*+#$%
⎯⎯⎯⎯⎯⎯⎯⎯)○o
WaterquicklyequilibrateswiththeCO2 atrechargeeventsanddissolutionofcarbonatesproceedstoequilibrium
CO2 +H2O→H2CO3§H2CO3+CaCO3→Ca++ +2HCO3-§
o
ThefollowingpredictionscanbemadeastowaterchemistryatequilibriumforagivenpCO2
pH○HCO3-○Ca+○CaCO3 neededforsaturation○Alkalinity○TIC○
o
pHrisesbecauseoftheadditionoftheconjugatebasepHof7– 8typical○
o
CarbonatesprovideanothersourceofHCO3- whenreactedwithH2CO3o
ClosedSystemDissolution•
NocarbonatesoccurintheunsaturatedzoneoCO2– chargedwaterentersthesaturatedzonewherecarbonatesdissolvetoequilibriumunderclosedconditions
o
pCO2willnotremainconstantItwilldecreaseasH2CO3isconsumed:
NodiffusionofCO2 throughthesaturatedporespaces§Sluggishgroundwaterflow§
○o
Consequently,atequilibrium:pHwillbesignificantlyhighercomparedtotheopensystemcaseforagiveninitialPCO2
H2CO3isconsumedwithoutreplenishment§Additionoftheconjugatebase§
○
LessCa++ andHCO3-○Loweralkalinity○LessCaCO3dissolvedforsaturation○LowerTIC○
o
RealworldconditionscanbeanywherebetweentheopenandclosedcaseoTypicalpHrangeintheshallowsaturatedzoneincarbonateterrainis7– 8oImpliestheopensystemmodelisatworkoThesaturatedzoneinthedeepsubsurfacemimicstheclosedsystemdissolutioncase
o
SomeControlsandInterferencesontheCarbonateSystem
Openvs.ClosedSystemDissolutionoInitialPCO2oCarbonatemineralavailabliityoIncompletediffusionofCO2intheunsaturatedzone
InitiallyhighPCO2dissolvescalcitetoequilibriumintheunsaturatedzone○ThewatermigratestoalowerpartoftheunsaturatedzonehavingalowerPCO2becauseofincompletediffusion
○
Result:DegassingofCO2§RiseinpH§PrecipitationofCaCO3§
○
o
TemperatureAffectsequilibriumconstants○CO2solubility○
o
CationexchangeoCommonioneffect
Calcite,Dolomite,Gypsum,Anhydrite○o
Ionicstrengtho
GroundwaterinCrystallineRocks
AKAsilicateterrainIgneousandmetamorphicrock○
•
Theserocksarecomprisedoftheprimaryrockformingsilicateminerals•Thesemineralsandrocksformedunderconditionsofhightemperatureand/orpressure
•
Theybecomeunstablewhenexposedtotheweatheringeffectsoftheatmosphere
ie:acidic,oxidizingconditions○
•
Theytherebytendtodissolveoralterintomorestableproducts•DiluterainwaterchargedwithCO2andO2 encounterssilicateminerals•Thesemineralsareaffectedbyhydrolysisandoxidationreactions•SiandaccessoryelementsareleachedwhileAltendstostaybehindresultinginformationofclayminerals
Incongruentdissolution=mineralalterationreaction○
•
DissolutionandalterationofsilicatesinvolvesconsumptionofacidResultsinariseinsolutionpHalongthegroundwaterflowpath○pH@6– 7typical○
•
AdiagnosticconstituentinthissettingisSianditsdifferentformsAtpH6– 7thestableformofSiisSi(OH)4§Typicalconcentrations@10– 30mg/LasSiO2§
•
SummaryofGroundwaterChemistryinSilicateTerrain
Asgroundwatertravelsalongitsflowpath:IncreasingpHasH+isconsumedbyhydrolysis
pH6– 7typical•pH7– 8ifreactionsgofarenough•
§o
IncreasingCa++,Mg++,K+ andNa+Cationsreleasedinresponsetohydrolysistomaintainelectricalneutrality§
o
IncreasingHCO3- (alkalinity)oIncreasingSioIncreasingTIC(asHCO3-)intheunsaturatedzone
FromreactionwithH2CO3§OpensystemdissolutionwithaconstantPCO2§CO2 isconstantlyreplenishedtoformH2CO3 evenasH2CO3isconsumed§
o
TICremainsconstantinthesaturatedzoneClosedsystemconditions§ItsformmaychangefromH2CO3 toHCO3-§
o
LowTDSoHCO3- isthedominantanionoCl- andSO4= arepresentinminor/traceamountsoSi(asSiO2)ispresentinmajoramountsrelativetoothercationso
GroundwaterinSedimentarySystems
Sedimentaryrocksandunconsolidatedsedimentarydepositsarecomplicatedsincetheyarecomprisedofmixedassemblagesofminerals
Bothbetweenbedsandwithinindividualbeds§
o
Therearelargedifferencesinwaterchemistryandthechemistrycanbehardtointerpret
o
Majorcontrols:Typeandamountofdifferentmineralsencountered§Mineralsolubility
Amountandrateofmineraldissolution•§
Orderofencounterofdifferentmineraltypes§
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Thiscanbeillustratedbylookingattwosimplified,hypotheticalhydrogeologicsystems
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Theremaybeothercontrolsongroundwaterchemistry:oSulfatereduction
2CH2O+SO4=→ HCO3-+HS-+CO2+H2O§HS- canbefurtherreducedtoH2S§
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Coalificationoflignite:Underheatandpressure§CnH2O→n/2CO2+½CnH2n+2§
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GroundwaterinGlacialDeposits
Thisincludesshallowgroundwateraffectedbydepositsoftill,glaciofluvialoutwashanddrumlinsupto~100feetthick
Lowcontacttime○Shorttraveldistance○Therealmofdugwaterwells○
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IllustratedontheSurficialGeologyMapofNovaScotiaoChemicalcompositionofwaterinthissettingisveryvariableoControlsandprocessesaresimilartothoseinsedimentarysystemsingeneral
Mineralavailability○Mineralsolubility○
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ThreecategorieshavebeenestablishedastogeneralcompositionReflecttheoriginoftheglacialmaterialinvolved○
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Type1o
Glacialmaterialderivedfromsilicateterrain○Composition
Affectedby:Lowsolubilityofsilicateminerals□Shortcontacttime□LittleconsumptionofH2CO3□
§○
Slightlyacidic@pH6– 7○Veryfresh@TDS<100mg/L○Na+ andCa++ aredominantcations○HCO3- isthedominantanion
DissociationofH2CO3§MineralreactionwithH2CO3§
○
Softwater○CorrosivewaterwithanegativeLangelier Index
LowpH§Lowalkalinity§LowTDS§LowCa++ hardness§
○
Type11o
Showsinfluenceofcarbonateterrain:Slightlyalkaline
pH@7– 8□HCO3- derivedfromreactionwithH2CO3□
§○
Fresh○Hard○Ca++ (andMg++)dominantcations○Ca++– HCO3- – typewatertypical○Cationexchangemaybeimportant○
Type111o
Reflectstheinfluenceofevaporitedeposits○Moderatelytoverysolubleminerals○WindsorGroupinN.S.
Halite(NaCl)§Sylvite(KCl)§Gypsum(CaSO4 .2H2O)§Calcite(CaCO3)§
○
Slightlyalkaline○Poorquality
Hard§Brackish§
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Highconcentrationsofthemajorions○
TheHydrogeologicSetting•
ThehydrogeologicsettingisimportanttoestablishincontaminantstudiesoFactorsthatrelatetosoilandgroundwaterflow
Flowdirection§Flowvelocity§Flowpattern§KandaquiferT§
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Factorsthatmayaffectsoilwaterandgroundwaterchemistryandthechemicalenvironment
Byestablishingthenaturalbackgroundchemistry,(monitoringwells,springs)subsequentchangesinchemistrymayindicatetheonsetofcontamination
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Aswell,themigrationandfateofcontaminantsinthesubsurfaceareaffectedbythesamephysical,chemicalandbiologicalprocessesaffectingnaturalwaterchemistry
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ChemicalEvolutionofGroundwaterSunday,January17,2016 3:51PM
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