nitrogen - uf/ifas · 2 learning objectives identify the forms of n in wetlands nitrogen understand...
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1
Biogeochemistry of WetlandsS i d A li tiS i d A li ti
Institute of Food and Agricultural Sciences (IFAS)
Science and ApplicationsScience and Applications
Wetland Biogeochemistry LaboratorySoil and Water Science Department
NITROGEN
6/22/2008 P.W. Inglett 16/22/2008 WBL 16/22/2008 16/22/2008 WBL 1
Instructor :Patrick [email protected]
Soil and Water Science DepartmentUniversity of Florida
Nitrogen
IntroductionN Forms, Distribution, Importance
Basic processes of N CyclesExamples of current researchExamples of applications
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Key points learned
2
Learning ObjectivesIdentify the forms of N in wetlands
Nitrogen
yUnderstand the importance of N in
wetlands/global processesDefine the major N processes/transformationsUnderstand the importance of microbial activity
in N transformations Understand the potential regulators of N
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processesSee the application of N cycle principles to
understanding natural and man-made ecosystems
Plant biomass NPlant biomass N
Nitrogen CyclingNitrogen Cycling
AEROBICAEROBIC
Organic N
Plantuptake
NO3-
Litterfall
Peataccretion
Nitrification Mineralization.
[NH4+]s
NH4+
[NH4+]s
NH4+NO3
-
N2 N2O (g)NH3
Volatilization
N2
Nitrogen Fixation
Water Water ColumnColumn
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ANAEROBICuptake
Adsorbed NH4+
Denitrification
accretion
Organic N
[ 4 ]s[ 4 ]s
NN2, N2O (g)
MicrobialBiomass N
3
Forms of NitrogenForms of Nitrogen
Organic Nitrogen• Proteins• Amino Sugars• Nucleic Acids
U
Inorganic Nitrogen• Ammonium (NH4
+)• Nitrate N (NO3
-)• Nitrite N (NO2
-) Nit id (N O)
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• Urea • Nitrous oxide (N2O)• Dinitrogen (N2)
Solid Phase:
Gaseous Phase:
N TransformationsN Transformations
Aqueous
Particulate N
Bound: NH4+
NO3- NO2
-
N2N2O
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NH4+
NO3-
NO2-
Aqueous Phase:
DON
Particulate NDIN
4
Reservoirs of NitrogenReservoirs of Nitrogen
Lithosphere 163,600 x 1018 gAtmosphere 3,860 x 1018 gHydrosphere 23 x 1018 gBiosphere 0.28 x 1018 g
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p g
Total Soil NForms of NitrogenForms of Nitrogen
Organic Inorganic
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NH4+
Clay-fixed NH4+
ProteinAmino sugarsHeterocyclic N
5
1. Ammonification/Mineralization
Nitrogen TransformationsNitrogen Transformations
2. Immobilization3. Nitrification4. Denitrification5. Dissimilatory nitrate reduction to
ammonia (DNRA)
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ammonia (DNRA)6. Nitrogen fixation7. Ammonia volatilization
NH4+
Organic N
8e-
1
5
2
Transformation of N SpeciesTransformation of N Species
NO3-
NO2-
N2O
NH3
2 e-
2e-
3e-
2e-
3
6
4NH2OH 4e-
2e-
7
4
33
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+5+3+10
-3
N2
Oxidation Number
1e-
3e
+2 +4-1-2
4
6
Nitrogen CycleNitrogen Cycle
Plant/Algae
Nit ifi D it ifi
Org-N NH4+ NO3
-
N Fi
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Nitrifiers Denitrifiers
N2/N2ON2
N-FixersMicrobial Biomass
Productivity Productivity
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7
Greenhouse Gas Emissions Greenhouse Gas Emissions
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Biological N2 fixationDry and wet depositionNon-point sourcesWastewaters
Nitrogen BudgetNitrogen Budget
Plant biomassMicrobial biomassSoil organic NPorewater (DIN, DON)Exchangeable N
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VolatilizationOutflowGaseous lossesPlant harvest
Clay fixed NH4-N
8
Ammonium Ion Wet Deposition1985-2003
1985
2003
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http://nadp.sws.uiuc.edu/isopleths/
Nitrate Ion Wet Deposition1985-20031985
2003
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9
Inorganic N Wet Deposition1985-20031985
2003
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Plant biomass NPlant biomass N
Biological Nitrogen FixationBiological Nitrogen Fixation
AEROBICAEROBIC
Organic N
Plantuptake
NO3-
Litterfall
Peataccretion
Nitrification Mineralization.
[NH4+]s
NH4+
[NH4+]s
NH4+NO3
-
N2 N2O (g)NH3
Volatilization
N2
Nitrogen Fixation
Water Water ColumnColumn
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ANAEROBICuptake
Adsorbed NH4+
Denitrification
accretion
Organic N
[ 4 ]s[ 4 ]s
NN2, N2O (g)
MicrobialBiomass N
10
Type of fixation N2 fixed (1012 g yr-1)Non-biological
Nitrogen FixationNitrogen Fixation
Industrial about 50Combustion about 20Lightning about 10Total about 80BiologicalAgricultural land about 90F t d i lt l l d b t 50
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Forest and non-agricultural land about 50Sea about 35Total about 175
Biological NBiological N22 FixationFixationN N + 8H+ + 8e- + 16ATP → 2NH3 + H2 + 16ADP + 16Pi
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Nitrogenase
11
Biological NBiological N22 FixationFixation
Prokaryotes
AzotobacterBeijerinckiaKlebsiella
C anobacteria
Aerobic
ClostridiumDesulfovibrioCyanobacteria
Anaerobic
RhizobiumFrankia
Azospirillum
Associated w/ Plants
y
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Cyanobacteria
Biological NBiological N22 FixationFixation
HeterocystsHeterocysts (cyanobacteria)Leghaemoglobin (rhizobium)ExopolysaccharidesTemporal isolation
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Temporal isolation
http://www.bact.wisc.edu/Microtextbook/ images/book_4/chapter_2/2-53.jpg
12
y
Temporal IsolationTemporal Isolation
Nitr
ogen
ase
activ
ity
Non-heterocystous
Heterocystous
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12:00Time (h)24:00 12:00
Biological NBiological N22 FixationFixationRegulators?Regulators?
LightLightConcentration of Oxygen Growth limitation
Macro nutrients (C, P) Co-factors (Fe, Mo)
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Inc. Growth
Inc. N Demand Species
shiftInc. N2Fixation
13
Plant biomass NPlant biomass N
Nitrogen MineralizationNitrogen Mineralization
AEROBICAEROBIC
Organic N
Plantuptake
NO3-
Litterfall
Peataccretion
Nitrification Mineralization.
[NH4+]s
NH4+
[NH4+]s
NH4+NO3
-
N2 N2O (g)NH3
Volatilization
N2
Nitrogen Fixation
Water Water ColumnColumn
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ANAEROBICuptake
Adsorbed NH4+
Denitrification
accretion
Organic N
[ 4 ]s[ 4 ]s
NN2, N2O (g)
MicrobialBiomass N
Organic NitrogenOrganic Nitrogen
ProteinsAmino acids (30-50% of total organic N)
Nucleic Acids 2-5 % of total organic N
Amino Sugars3-13% of total organic N
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3-13% of total organic N
Urea
14
Proteins
A i idPeptides
Protein DecompositionProtein Decomposition
Amino acidsPeptides
Proteases PeptidasesAla
Phe
Asp
L
Pro
Arg
Pro
Ala
Phe
Asp
Lys
Pro
Arg
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Pro
Lys
N - C - C - OHOR1
HH
HN - C - C - OH
OR2
HH
HN - C - C - OH
OR3
HH
H
N - C - C - NOR1
- C - C - N
OR2
- C - C - OHOR3H
- 2H2O
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HH HH HH
Peptide Bonds
15
N - C - C - OHOR1
HH
HN - C - C - OH
OR2
HH
HN - C - C - OH
OR3
HH
H
HH HH HH
N - C - C - NOR1
- C - C - N
OR2
- C - C - OHOR3H
+ 2H2O
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HH HH HH
Peptide Bonds
EnzymeHydrolysis
Detrital MatterComplex PolymersCellulose, Hemicellulose,
Proteins, Lipids, Waxes, Lignin
MonomersSugars, Amino Acids
Fatty Acids
Leaching
Amino acidsElectron Acceptors:O2, NO3
-, Mn4+, Fe3+, SO4
2-, CO2
Uptake
Bacterial Cell
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Products:CO2, H2O,
NH4+, Mn2+,
Fe2+,S2-,CH4
ATPEnergy
NH4+
NH4+
16
Urea DecompositionUrea Decomposition
C = O + H2O CO2 + 2NH3
NH2
NH2
Urease
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Urea DecompositionUrea Decomposition
Urease activity (14C Tracer)
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[Thorén (2007)]
17
AmmonificationAmmonification[Mineralization]
Organic N Ammonium N[B kd f O i M tt ][Breakdown of Organic Matter]
ImmobilizationImmobilization
Inorganic N Organic N
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Inorganic N(NH4-N and NO3 -N)
Organic N
[Buildup of Organic Matter]
Ammonification/NAmmonification/N--MineralizationMineralizationOrganic N
AmmoniumRR
NN--ImmobilizationImmobilizationInorganic N Organic N
NH4+
NH2C
H
-HOOC NH2C
H
-HOOC
RR
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NH4+
NO3-
NH2C
R
H
-HOOC NH2C
R
H
-HOOC
18
y = 10.7 x + 2.2R2 = 0.78 25
Microbial Biomass C & NMicrobial Biomass C & N[Everglades[Everglades-- WCAWCA--2A]2A]
0
5
10
15
20
crob
ial b
iom
ass
C(g
C k
g-1 )
6/22/2008 P.W. Inglett 35
0
0 0.5 1.0 1.5 2.0
Microbial biomass N (g N kg-1)
Mic
White and Reddy, 2000
Decomposition Decomposition Microbial Biomass
C/N ratio = 10Effi i f b i il tiEfficiency of carbon assimilation
Aerobic = 20-60% Anaerobic = 10%
Plant Detritus [100 units]40% carbon (dry weight basis) = 40 units CAmount of C assimilated during decomposition
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Amount of C assimilated during decompositionAerobic = 16 units [40% efficiency]Anaerobic = 4 units [10% efficiency]
19
Carbon/Nitrogen RatioCarbon/Nitrogen Ratio
Nitrogen Demand?Mi bi l Bi C/N ti 10Microbial Biomass C/N ratio = 10
Aerobic = 1.6 unitsAnaerobic = 0.4 units
Critical Plant Detritus Nitrogen?Aerobic = 1.6 %Anaerobic = 0.4%
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Critical Carbon/Nitrogen Ratio?Aerobic = [40% C]/[1.6% N] = 25Anaerobic = [40% C]/[0.4% N] = 100
Carbon/Nitrogen RatioCarbon/Nitrogen Ratio
Mineralization [M] vs. Immobilization [I]
Aerobic I > M = C/N ratio > 25M > I = C/N ratio < 25
AnaerobicI M C/N ti 100
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I > M = C/N ratio > 100M > I = C/N ratio < 100
20
C/N = 15ease
N Mineralization/ImmobilizationN Mineralization/Immobilization[Aerobic][Aerobic]
C/N = 35
C/N = 100norg
anic
N R
ele
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Decomposition (days)
In
Immobilization
n R
atio 40
N Mineralization/ImmobilizationN Mineralization/Immobilization[Aerobic][Aerobic]
Mineralization
arbo
n/N
itrog
en
10
20
30
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Ca
0
Decomposition Period [days]0 150
C/N ratio of soil humus/microbial biomass
21
Regulators of AmmonificationRegulators of Ammonification
Substrate qualityC/N ratio of the substrateC/N ratio of the substrateSecondary compoundsN forms (soluble vs. structural compounds)
Microbial ActivityExtracellular enzyme activity
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Extracellular enzyme activitySupply of electron acceptors (Redox)TemperaturepH
400
Mineralizable NitrogenMineralizable Nitrogen[Everglades[Everglades--WCAWCA--2A]2A]
y = 0.317 x + 52.4R2 = 0.76
100
200
300
400
Min
eral
izat
ion
Rat
e(m
g N
kg-
1d-
1 )
6/22/2008 P.W. Inglett 42
00 100 200 300 400
Extractable NH4+ (mg N kg-1)
M
22
Plant biomass NPlant biomass N
Fate of AmmoniumFate of Ammonium
AEROBICAEROBIC
Organic N
Plantuptake
NO3-
Litterfall
Peataccretion
Nitrification Mineralization.
[NH4+]s
NH4+
[NH4+]s
NH4+NO3
-
N2 N2O (g)NH3
Volatilization
N2
Nitrogen Fixation
Water Water ColumnColumn
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ANAEROBICuptake
Adsorbed NH4+
Denitrification
accretion
Organic N
[ 4 ]s[ 4 ]s
NN2, N2O (g)
MicrobialBiomass N
Nitrogen Uptake by Rice (Nitrogen Uptake by Rice (1515N)N)
T t l N t kTotal N uptake
Added 15N uptake
N-uptake fromNitr
ogen
upt
ake
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upta e oSoil organic N
Growing season
23
NH +
Ammonium AdsorptionAmmonium Adsorption-- AerobicAerobic
---
- Ca2+
K+NH4
+
Mg2+
Ca2+
NH4
K+
Mg2+
Ca2+
Ca2+
K+
-
-
-
--
--
-
--
------
-
-
- K+
K+
Ca2+ NH4+
NH4+ Mg2+
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Adsorbed [Solids]
Dissolved[Pore water]
-- - Ca2+Mg2+
K+K+
Ammonium AdsorptionAmmonium Adsorption-- AnaerobicAnaerobic
NH4+
C 2+----
- -K+
Ca2+
Mg2+
Fe2+
Mn2+Fe2+
4
K+
Mg2+
Ca2+
Ca2+
K+
-
-
--
--
-
--
- ------
-
-K+
NH4+
NH4+ Mg2+
Mn2+
Fe2+
Fe2+
Mn2+
Mn2+
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Adsorbed [Solids]
Dissolved[Pore water]
K- - Ca2+Mg2+
K+Fe2+
24
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Ammonium Fixation Ammonium Fixation Illite Illite -- Clay MineralClay Mineral
NH4+K+NH4
+Mg2+ ---
--
---
- --NH4
+K+
Mg2+
Ca2+ K+ Al-O-OH layerSi-O layer
Si O layer
Ca2+
NH4+K+NH4
+Mg2+ -- --- - --NH4
+NH4+
NH4+
Fixed Ammonium
NH4+K+NH4
+Mg2+ ---
--
--- - -
- --
-NH4
+
NH4+
NH4+
NH4+
- - -Interlayer Space
Si-O layer
NH +
Interlayer Space
6/22/2008 P.W. Inglett 48
Mg2+
Mg2+
NH4+
Ca2+K+
K+
--- - - -NH4
+
25
Adsorption/Desorption EquilibriumAdsorption/Desorption Equilibrium
NH +NH4
+
SoilNH4
+
NH4+ 4
NH4+NH4
+
NH +
NH4+
NH4+
6/22/2008 P.W. Inglett 49
NH4+NH4
+ NH4
Fixed Exchangeable Solution
Adsorption/Desorption EquilibriumAdsorption/Desorption Equilibrium
NH4+
NH4+
NH4+
NH4+
NH4+
NH4+
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NH4+
NH4+
NH4+
26
(+)
NH4+
ads = K × [NH4+] + NH4
+fixed
S = K × C + S0
K, Partition Coefficient
E NH4-C0
mm
oniu
m A
dsor
bed
(mg
N k
g-1 )
( )
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Porewater ammonium (mg N l-1)
Am
(-)S0
Ammonium Adsorption Ammonium Adsorption -- SalinitySalinity
6/22/2008 P.W. Inglett 52
27
Increasing salinityIncreasing salinity
6/22/2008 P.W. Inglett 53
NH3(g)
Ammonia FluxAmmonia Flux
(Volatilization)(Volatilization)
Water
2H+ + CO32- CO2 + H2O
Photosynthesis
Respiration
O2 + CH2O CO2 + H2O NH3(g)
NH4+NH3(aq) + H+
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Soil
Water
NH4+
(adsorbed)
28
Diel pH changes in the Diel pH changes in the Water ColumnWater Column
7
8
9
10
pH
System with high photosynthesis
System with low photosynthesis
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12:00
6
7
Time (h)
24:00 12:00
Ammonia VolatilizationAmmonia Volatilization(assuming high pH)(assuming high pH)
SAV/Periphyton DensityFloodwater depth Plant density
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Temperature Wind speed Soil CEC
29
Ammonia VolatilizationAmmonia Volatilization
NH + = NH + H+ TemperatureNH4 = NH3 + HHigh floodwater pH High soil pHHigh algal activityPlant density
TemperatureCation exchange capacity of soilWind speedFloodwater depth
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Plant biomass NPlant biomass N
NitrificationNitrification
AEROBICAEROBIC
Organic N
Plantuptake
NO3-
Litterfall
Peataccretion
Nitrification Mineralization.
[NH4+]s
NH4+
[NH4+]s
NH4+NO3
-
N2 N2O (g)NH3
Volatilization
N2
Nitrogen Fixation
Water Water ColumnColumn
6/22/2008 P.W. Inglett 58
ANAEROBICuptake
Adsorbed NH4+
Denitrification
accretion
Organic N
[ 4 ]s[ 4 ]s
NN2, N2O (g)
MicrobialBiomass N
30
NH + → NO → NO
NitrificationNitrification
NH4+ → NO2
- → NO3-
Obligate aerobes (O2 e- acceptor)Common nitrifiers (autotrophs)MethanotrophsH t t h
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Heterotrophs
Sites of NitrificationSites of NitrificationAerobic
Water column
O2 bic
Soil
Aerobic Soil/FloodwaterInterface
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AerobicRoot Zone
O2
Aer
ob
Ana
erob
ic S
oil
O2
31
NitrificationNitrification
NH4+ → NO2
- Nitrosomonas (‘Nitroso’ spp.)
NO2- → NO3
- Nitrobacter (‘Nitro’ spp.)
Obligate aerobes (O2 e- acceptor)Energy/e- source: NH4
+
Carbon source: CO
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Carbon source: CO2
NitrificationNitrificationStep I: Nitrosomonas
NH4+ + 2H2O → NO2
- + 6e- + 8H+
ΔGo = -65 kcal/mole
1½ O2 + 6e- + 6H+ → 3H2O
NH4+ + 11/2O2 → NO2
- + 3H2O + H+
Step II: Nitrobacter ΔGo = -18 kcal/mole
2NO 2H O 2NO 4 4H+
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2NO2- + 2H2O → 2NO3
- + 4e- + 4H+
O2 + 4e- + 4H+ → 2H2O
2NO2- + O2 → 2NO3
-
32
B t i d f i
Heterotrophic NitrificationHeterotrophic Nitrification
Bacteria and fungiPoorly studiedOnly dominant under high C/low N conditionsMany facultative (reduce oxidized N to N2)
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2
“Nitrifier denitrification”
NitrificationNitrification
AmmoniaAmmoniaNH3 toxic to nitrifying bacteriapH7 - 8.5 optimumSulfide
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S2- toxic to nitrifying bacteria
33
NitrificationNitrification
Ideal Conditions Inhibited
C
NH4+ NH4
+
NO2-
NO2-NO3
-
NO3-
6/22/2008 P.W. Inglett 65
C
Time Time
Oxygenases Hydroxylamineid d t
NitrificationNitrification
NH4+ NH2OH [NOH]
NO2-N2O NO3
-
yg oxidoreductase
Chemical
2 e- 2 e-
2 e-
2 e-
Oxygenstress
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NO2N2O NO3Nitrite
reductaseNitrite
reductase
34
Inhibited NitrificationInhibited Nitrification
NO3-NH4
+ N2
N2O
NO
Nitrifiers Denitrifiers
NO
N2O
‘Leaky Pipe’ Model:
6/22/2008 P.W. Inglett 67
22
Regulators: Ammonia concentration
NitrificationNitrification
Ammonia concentrationOxygen availabilityAlkalinity and CO2
TemperatureNitrifying population
6/22/2008 P.W. Inglett 68
pHCEC
35
Organic NOrganic N
AmmonificationVolatilization
(to atmosphere)
NHNH44++ NHNH44
++Soluble Adsorbed
[NH[NH33 ]](g)(g)
[NO[NO33-- ]]
-
-
--
-
-
-
Soi
l Par
ticle
-
ant/M
icro
bial
U
ptak
e
6/22/2008 P.W. Inglett 69
Live Organic N
Live Organic N
Pl
Anaerobic Ammonium Oxidation: Anammox
Anaerobic Ammonium Oxidation: Anammox
6/22/2008 P.W. Inglett 70Kuypers et al. 2003. Nature 422:608–611.
36
Anaerobic Ammonium OxidationAnaerobic Ammonium Oxidation(ANAMMOX)(ANAMMOX)
5NH4+ + 3NO3
- → 4N2 + 9H2O + 2H+
NH + + NO - → N + 2H O
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NH4 + NO2 → N2 + 2H2O
ANAMMOXANAMMOX
6/22/2008 P.W. Inglett 72
37
Plant biomass NPlant biomass N
DenitrificationDenitrification
AEROBICAEROBIC
Organic N
Plantuptake
NO3-
Litterfall
Peataccretion
Nitrification Mineralization.
[NH4+]s
NH4+
[NH4+]s
NH4+NO3
-
N2 N2O (g)NH3
Volatilization
N2
Nitrogen Fixation
Water Water ColumnColumn
6/22/2008 P.W. Inglett 73
ANAEROBICuptake
Adsorbed NH4+
Denitrification
accretion
Organic N
[ 4 ]s[ 4 ]s
NN2, N2O (g)
MicrobialBiomass N
Pasteur, L. 1859. Sur la fermentation nitreuse. Bull. Sot. Chim. Fr. 1:21.
“Nitrates, which the juice of beetroot naturally includes, decompose, and great quantities of nitrous vapor form at the surface of the vats”
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38
Dehérain andDehérain and Maquenne, 1882Maquenne, 1882. Sur la reduction des nitrates dans la terre arable. C. R. Acad. Sci. 95: 691-693
“From experience”:Nitrate is reduced under certain conditions
in arable land releasing nitrogen gasNitrate reduction occurs in arable soil
which contains a high organic matter
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g gWe have observed that this reduction
occurs when the soil atmosphere is completely stripped of oxygen
Denitrification NO → N
Nitrate ReductionNitrate Reduction
5 e-NO3 → N2
Dissimilatory nitrate reduction to ammonia (DNRA)NO3
- → NH4+
Assimilatory nitrate reduction to i
8 e-
6/22/2008 P.W. Inglett 76
ammoniaNO3
- → NH4+ → Proteins
39
Nitrate ReductionNitrate Reduction
AssimilatoryNH + uptake for
Dissimilatory Functions as an electronNH4
+ uptake for growth - biosynthesisNH4
+ concentration-main regulatorGrowth linkedOccurs mainly in
Functions as an electron acceptorOxygen concentration main regulatorLinked to catabolic reactions
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aerobic soilsInsensitive to O2
Occurs in anaerobic soilsSensitive to O2
Nitrate ReductionNitrate ReductionDenitrification
NO - /NO -→ NDNRA
NO -→ NH +NO3 /NO2 → N25 e- transferred Low electron pressureEh = 200 – 300 mVO2 transient
diti
NO3 → NH48 e- transferredHigh electron pressureEh = < 0 mVLake sediments or
t tl d
6/22/2008 P.W. Inglett 78
conditionsFacultative anaerobes
permanent wetlandsObligate anaerobes
40
Low O content Low Eh
Regulators of DenitrificationRegulators of Denitrification
Low O2 content - Low Eh Presence of Electron Acceptor- N OxidesFacultative Anaerobes - EnzymesElectron Donor - Carbon Source
Organic carbon compoundsReduced sulfur compounds
Temperature
6/22/2008 P.W. Inglett 79
Nitrate diffusion/flux to anaerobic zonesPlant root density
Sites of Nitrification/DenitrificationSites of Nitrification/DenitrificationAerobic
Water column
O2 bic
Soil
Aerobic Soil/FloodwaterInterface
6/22/2008 P.W. Inglett 80
AerobicRoot Zone
O2
Aer
ob
Ana
erob
ic S
oil
O2
41
NO3- NO2
- [HNO] [H2N2O2]
Dissimilatory Nitrate ReductionDissimilatory Nitrate Reduction
NO3 NO2 [HNO] [ 2 2 2]
NH2OH N2OBiological
[HNO] = Nitroxyl[H2N2O2] = Hyponitrite
6/22/2008 P.W. Inglett 81
NH4+ N2
[ 2 2 2] ypNH2OH = Hydroxylamine
DNRA Denitrification
Abiotic Nitrate ReductionAbiotic Nitrate Reduction(‘Chemo(‘Chemo--denitrification’)denitrification’)
Abiotic Nitrate ReductionAbiotic Nitrate Reduction(‘Chemo(‘Chemo--denitrification’)denitrification’)
6/22/2008 P.W. Inglett 82
42
Abiotic Nitrate ReductionAbiotic Nitrate ReductionAbiotic Nitrate ReductionAbiotic Nitrate Reduction
6/22/2008 P.W. Inglett 83
Lithotrophic Nitrate ReductionLithotrophic Nitrate ReductionLithotrophic Nitrate ReductionLithotrophic Nitrate Reduction
OthOther potential e- donors:S2-, H2
6/22/2008 P.W. Inglett 84
43
w/ added NO3-
N.R. Coupled to Fe(II) Oxidation:Paddy Soils
N.R. Coupled to Fe(II) Oxidation:Paddy Soils
w/o added NO3
-
w/ added NO3
-
w/o added
6/22/2008 P.W. Inglett 85
Ratering and Schnell. 2001. Env. Microbiol. 3(2), 100-109.
Fe(II) Fe(III)
NO3-
NO3--control
N.R. Coupled to Fe(II) Oxidation N.R. Coupled to Fe(II) Oxidation
NO3- + Fe(II) → NO2
- → Fe(III) + N2
Fe(III)-culture
NO3--culture
6/22/2008 P.W. Inglett 86
Straub, et al. 2007. Appl. Env. Microbiol. 62: 1458-1460.
Fe(III)-control
44
N2N2
NO3-NO3-
NH4+NH4+ NO2
-NO2-
O2/Fe3+
6/22/2008 P.W. Inglett 87
CH4?
6/22/2008 P.W. Inglett 88
45
Low O2 content - Low Eh Presence of Nitrogenous Oxides
Regulators of DenitrificationRegulators of Denitrification
Presence of Nitrogenous OxidesHeterotrophs: Carbon Source
Organic carbon compounds, DOCLithotrophs: Electron Source
Reduced Fe, Mn, S compounds, H2
TemperatureNitrate diffusion/flux to anaerobic zones
6/22/2008 P.W. Inglett 89
Nitrate diffusion/flux to anaerobic zonesPlant root density
Nitrate uptake, O2 loss
DenitrificationDenitrificationDenitrificationDenitrificationWetlandWetland Denitrification RateDenitrification Rate
Houghton Lake WetlandInflow ZoneInterior Zone
(mg N kg-1 day-1)7411
Orange County ESAWT 91
Inflow ZoneInterior Zone
6/22/2008 P.W. Inglett 90
Everglades-WCA-2a61
1Interior Zone
Inflow ZoneInterior Zone
46
Coupled NitrificationCoupled Nitrification--DenitrificationDenitrification
Nitrification rate depends on:Ammonification rateAmmonium flux into aerobic zone
Denitrification rate depends on:Nitrification rateNitrate flux into anaerobic zones
Nitrification-denitrification occurs in:
6/22/2008 P.W. Inglett 91
Flooded soil-water column with aerobic-anaerobic interfacesAerobic-anaerobic interfaces in the root zoneWater-table fluctuations/ alternate flooding and draining
Coupled NitrificationCoupled Nitrification--DenitrificationDenitrificationCoupled NitrificationCoupled Nitrification--DenitrificationDenitrification
6/22/2008 P.W. Inglett 92From: Reddy (1989)
47
10
Everglades –WCA-2AEverglades –WCA-2ANitrate source/ High C/Low Eh Nitrate depleted/
High C/Low Eh
Nitrate source/ Low C,P/Low Eh
trific
atio
n R
ate
g N
kg
-1hr
-1)
4
6
8
10
With GlucoseWithout Glucose
6/22/2008 P.W. Inglett 93
Den
i(m
g
Distance (km)
0
2
0 2 4 6 8 10
Denitrification Walls:(Schipper et al. 2003)
48
Supply of NO2-
ANAMMOX vs. DenitrificationANAMMOX vs. DenitrificationANAMMOX vs. DenitrificationANAMMOX vs. Denitrification
pp y 2Low NO2
- favors Denitrification, High NO2- (>10mM)
inhibits ANNAMOX
Organic matter availabilityHigher DOC favors Denitrification
Temperature
6/22/2008 P.W. Inglett 95
Temperature ANNAMOX dominant @ low Temp.
6/22/2008 P.W. Inglett 96
49
Supply of NO3-
Denitrification vs. DNRADenitrification vs. DNRADenitrification vs. DNRADenitrification vs. DNRA
Supply of NO3Low NO3
- favors DNRA
Organic matter availabilityHigh DOC favors DNRA
Hydropattern
6/22/2008 P.W. Inglett 97
Denitrifiers are largely facultative
ON
(Of added 15NO3-)
6/22/2008 P.W. Inglett 98
51
Potential FatePotential FatePotential FatePotential FateLow Organic
Matter (Low C:EA)
NO
NO3-
NO2-
N2
N2ONH4
+
N2
N2O
N
N2
Dissim
ila
H+
NO
6/22/2008 P.W. Inglett 101
High Organic Matter
(High C:EA)AerobicAnaerobic
NH4+
N2
atory
Permanently Anaerobic
Potential FatePotential FatePotential FatePotential Fate
6/22/2008 P.W. Inglett 102
Burgin and Hamilton. 2007. Front Ecol Environ 5(2): 89–96.
52
Plant biomass NPlant biomass N
Nitrogen CyclingNitrogen Cycling
AEROBICAEROBIC
Organic N
Plantuptake
NO3-
Litterfall
Peataccretion
Nitrification Mineralization.
[NH4+]s
NH4+
[NH4+]s
NH4+NO3
-
N2 N2O (g)NH3
Volatilization
N2
Nitrogen Fixation
Water Water ColumnColumn
6/22/2008 P.W. Inglett 103
ANAEROBICuptake
Adsorbed NH4+
Denitrification
accretion
Organic N
[ 4 ]s[ 4 ]s
NN2, N2O (g)
MicrobialBiomass N