Chapter 5Chapter 5

The Biogeochemical CyclesThe Biogeochemical Cycles

In all things there is a law of cycles.-Pubilus Cornelius Tacitus(Roman Historian)

Lake WashingtonLake Washington

5.1 How Chemicals Cycle5.1 How Chemicals Cycle

Chemical- an element like C or P Chemical- an element like C or P oror a a compound like NHcompound like NH33..

Biogeochemical cycle- complete path Biogeochemical cycle- complete path a chemical takes through Earth’s a chemical takes through Earth’s major reservoirs major reservoirs ((bio-bio- involves life; involves life; geo-geo- include include atmos., water, rock, soil; atmos., water, rock, soil; chemical-chemical- chemicals are cycled) chemicals are cycled)

– AtmosphereAtmosphere– Hydrosphere (ocean, lake, river, Hydrosphere (ocean, lake, river,

groundwater, glacier)groundwater, glacier)– Lithosphere (rock & soil)Lithosphere (rock & soil)– Biosphere (plants & animals)Biosphere (plants & animals)

© 2008 John Wiley and Sons Publishers

© 2008 John Wiley and Sons Publishers

Rate of transfer/flux: the amount per unit time of a Rate of transfer/flux: the amount per unit time of a chemical that enters or leaves a storage chemical that enters or leaves a storage compartmentcompartment

Sink: the compartment that receives the chemicalSink: the compartment that receives the chemical– Ex: forests (measured in units – billions of metric tons)Ex: forests (measured in units – billions of metric tons)

Residence time: the average length of time that an Residence time: the average length of time that an atom is stored before its transferedatom is stored before its transfered

5.3 Biogeochemical Cycles and 5.3 Biogeochemical Cycles and Life:Life:

Limiting FactorsLimiting Factors MacronutrientsMacronutrients

– Elements required in large amounts by all lifeElements required in large amounts by all life– Include the “big six” elements that form the fundamental Include the “big six” elements that form the fundamental

building blocks of life:building blocks of life:carboncarbon oxygenoxygen

hydrogenhydrogen phosphorusphosphorusnitrogennitrogen sulfursulfur

MicronutrientsMicronutrients– Elements required either in Elements required either in

small amounts by all life or small amounts by all life or moderate amounts by some forms of life and not all by moderate amounts by some forms of life and not all by

othersothers Limiting factorLimiting factor

– When chemical elements are not available at the right When chemical elements are not available at the right times, in the right amounts, and in the right times, in the right amounts, and in the right concentrations relative to each otherconcentrations relative to each other

Micronutrients (human Micronutrients (human body)body)

5.4 The Geologic Cycle5.4 The Geologic Cycle

The Geologic Cycle:The Geologic Cycle:– The processes responsible for formation The processes responsible for formation

and change of Earth materialsand change of Earth materials– Best described as a group of cycles:Best described as a group of cycles:

TectonicTectonic HydrologicHydrologic RockRock BiochemicalBiochemical

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Geologic cycleGeologic cycle

Tectonic CycleTectonic Cycle Tectonic cycle:Tectonic cycle:

– Involves creation and destruction of the solid Involves creation and destruction of the solid outer layer of Earth, the lithosphereouter layer of Earth, the lithosphere Lithosphere: 100 km (60 mi) thick and is broken Lithosphere: 100 km (60 mi) thick and is broken

into platesinto plates

Plate tectonics:Plate tectonics:– The slow movement of these large segments The slow movement of these large segments

of Earth’s outermost rock shell of Earth’s outermost rock shell – Boundaries between plates are geologically Boundaries between plates are geologically

active areasactive areas Float on denser material and move 2-15 cm/year Float on denser material and move 2-15 cm/year

(as fast as fingernails grow)(as fast as fingernails grow)

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Tectonic Cycle: Plate Tectonic Cycle: Plate BoundariesBoundaries

Divergent plate boundary:Divergent plate boundary:– Occurs at a spreading ocean ridge, Occurs at a spreading ocean ridge,

where plates are moving away from one where plates are moving away from one anotheranother

– New lithosphere is produced (seafloor New lithosphere is produced (seafloor spreading)spreading)

Divergent…Divergent…

Tectonic Cycle: Plate Tectonic Cycle: Plate BoundariesBoundaries

Convergent plate boundaryConvergent plate boundary– Occurs when plates collideOccurs when plates collide

Produces linear coastal mountain ranges or Produces linear coastal mountain ranges or continental mountain rangescontinental mountain ranges

Result: upfolded mountains Example: Himalyas and Appalacian Mts.

Result: trench and volcanic island arcs Example: Aleutian Trench and Aleutian Islands

Tectonic Cycle: Plate Tectonic Cycle: Plate BoundariesBoundaries

Transform fault boundaryTransform fault boundary– Occurs where one plate slides past Occurs where one plate slides past

anotheranother San Andreas Fault in CaliforniaSan Andreas Fault in California

Wallace Creek- Carrizo Wallace Creek- Carrizo PlainsPlains

Offset100 yards

All 3…All 3…

Hydrologic CycleHydrologic Cycle“Water Cycle”“Water Cycle”

Water CycleWater Cycle Role of Water?Role of Water?

– Terrestrial ecosystems: major factor Terrestrial ecosystems: major factor determining distribution of organismsdetermining distribution of organisms

– Aquatic ecosystems: literally matrix that Aquatic ecosystems: literally matrix that surrounds & serves as environment of surrounds & serves as environment of aquatic organismsaquatic organisms

– Flows of water are major means for material Flows of water are major means for material & energy transfer& energy transfer

– Water Is critical for human activities: Water Is critical for human activities: agriculture, industry, and municipal useagriculture, industry, and municipal use

Water is the driver of nature.- Leonardo da Vinci

Water Cycle: Main Water Cycle: Main ProcessesProcesses

Evaporation:Evaporation: conversion from liquid to vapor conversion from liquid to vapor (surface to atmosphere)(surface to atmosphere)

Transpiration:Transpiration: evaporation of water from evaporation of water from leavesleaves

Condensation:Condensation: conversion of vapor to liquid conversion of vapor to liquid (ex: water droplets of water on cold soda can)(ex: water droplets of water on cold soda can)

Precipitation:Precipitation: movement as rain, sleet, hain, & movement as rain, sleet, hain, & snow (atmosphere to surface)snow (atmosphere to surface)

Infiltration:Infiltration: movement into soil movement into soil Percolation:Percolation: downward flow through soil to downward flow through soil to

aquifersaquifers Runoff:Runoff: surface flow down slope to ocean, river, surface flow down slope to ocean, river,

or lake.or lake.

Water CycleWater Cycle Withdraw large quantities of freshwater- Withdraw large quantities of freshwater-

water diversion, ground water depletion, water diversion, ground water depletion, wetland drainagewetland drainage

Clear vegetation- increase runoff, Clear vegetation- increase runoff, decrease infiltration & groundwater decrease infiltration & groundwater recharge, increase flooding & soil erosion.recharge, increase flooding & soil erosion.

Modify water quality- add nutrients (P, N, Modify water quality- add nutrients (P, N, K,…) and pollutantsK,…) and pollutants

The Water The Water CycleCycle Condensationconversion of

gaseous water vapor into liquid water

Transport overland: net movement of water vapor by wind

Evaporation from the ocean

Evaporation

Evaporation from inland

lakes and rivers

Evaporation from the

land

Lakes Ocean storage97% of total water

Transpiration

Transpiration

from plants

RiversWater locked up

in snow and ice

Groundwater movement (slow)

Surface runoff (rapid)

Infiltration: movement of water

into soilAquifers:

groundwater storage

areasPercolation: downward flow of

water

Precipitation

over the

ocean

Rain clouds

Precipitation

Precipitation(rain, sleet, hail, snow, fog)

Precipitatio

n to land

The The hydrologicalhydrological ( (waterwater) cycle, ) cycle,

collects, purifies, and distributes collects, purifies, and distributes

the Earth’s water.the Earth’s water.

Over the oceans, Over the oceans, evaporationevaporation exceeds exceeds precipitationprecipitation. This . This results in a net movement of results in a net movement of water vapor over the land.water vapor over the land.

On land,On land, precipitation exceeds precipitation exceeds evaporation. Some precipitation evaporation. Some precipitation becomes locked up in snow and becomes locked up in snow and ice for varying lengths of time.ice for varying lengths of time.

Most water forms surface and Most water forms surface and groundwater systems that flow groundwater systems that flow back to the sea.back to the sea.

Water TransformationsWater Transformations

Precipitation

Rivers and streams

Humans intervene in the water cycle by Humans intervene in the water cycle by

utilizing the resource for their own needs. utilizing the resource for their own needs.

Water is used for consumption, municipal Water is used for consumption, municipal

use, in agriculture, in power generation, use, in agriculture, in power generation,

and for industrial manufacturing.and for industrial manufacturing.

Industry is the greatest withdrawer of Industry is the greatest withdrawer of

water but some of this is returned. water but some of this is returned.

Agriculture is the greatest water consumer.Agriculture is the greatest water consumer.

Using water often results in its Using water often results in its

contamination. The supply of contamination. The supply of potablepotable

(drinkable) water is one of the most (drinkable) water is one of the most

pressing of the world’s problems.pressing of the world’s problems.

The DemandThe Demand for Waterfor WaterHydroelectric power generation…

Irrigation…

Washing, drinking,bathing…

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The Rock CycleThe Rock Cycle

The rock cycle:The rock cycle:– Numerous processes that produce rocks Numerous processes that produce rocks

and soilsand soils– Depends on other cycles:Depends on other cycles:

tectonic cycle for energy tectonic cycle for energy Hydrologic cycle for water Hydrologic cycle for water

– Rock is classified as Rock is classified as IgneousIgneous SedimentarySedimentary MetamorphicMetamorphic

© 2008 John Wiley and Sons Publishers

ElementElementMain Main

nonliving nonliving storehousestorehouse

Main forms in Main forms in living living

organismsorganisms

Other Other nonliving nonliving

storehousestorehouse

CarbonCarbon

(C)(C)

Atmospheric:Atmospheric:

Carbon dioxide Carbon dioxide (CO(CO22))

Carbohydrates:Carbohydrates: organic moleculesorganic molecules

Hydrologic:Hydrologic: dissolved carbonate dissolved carbonate (CO(CO33

2-2-) and ) and bicarbonate (HCObicarbonate (HCO33

--))

Sedimentary:Sedimentary: carbon containing carbon containing minerals in rocksminerals in rocks

NitrogenNitrogen

(N)(N)

Atmospheric:Atmospheric:

Nitrogen gas (NNitrogen gas (N22))ProteinsProteins and other and other nitrogen-containing nitrogen-containing organic moleculesorganic molecules

Hydrologic:Hydrologic: dissolved dissolved ammonium (NHammonium (NH44

++) ) and nitrate (NOand nitrate (NO22

--) in ) in water and soilswater and soils

PhosphorouPhosphorous s

(P)(P)

Sedimentary:Sedimentary:

Phosphate (POPhosphate (PO443-3-) )

containing minerals containing minerals in rocksin rocks

DNADNA. Other nucleic . Other nucleic acids (ATP) and acids (ATP) and phospholipidsphospholipids

Hydrologic:Hydrologic: dissolved phosphate dissolved phosphate (PO(PO44

3-3-))

SulfurSulfur

(S)(S)

Sedimentary:Sedimentary: rocks (e.g., Iron rocks (e.g., Iron disulfide & pyrite) disulfide & pyrite) and minerals e.g., and minerals e.g., sulfate [SOsulfate [SO44

2-2-])])

Sulfur-Sulfur- containing containing amino acids in most amino acids in most proteins, some proteins, some vitaminsvitamins

Atmospheric:Atmospheric: hydrogen sulfide hydrogen sulfide (HgS), sulfur dioxide (HgS), sulfur dioxide (SO(SO22), sulfur trioxide ), sulfur trioxide (SO(SO33), and sulfuric acid ), and sulfuric acid (H(H22SOSO44))

Hydrologic:Hydrologic: sulfate sulfate (SO(SO44

2-2-) and sulfuric acid) and sulfuric acid

Carbon CycleCarbon Cycle

Carbon CycleCarbon Cycle Building block of organic molecules Building block of organic molecules

(carbohydrates, fats, protein, & nucleic (carbohydrates, fats, protein, & nucleic acids)- essential to lifeacids)- essential to life

Currency of energy exchange- chemical Currency of energy exchange- chemical energy for life stored as bonds in organic energy for life stored as bonds in organic compoundscompounds

Carbon dioxide (COCarbon dioxide (CO22) greenhouse gas- ) greenhouse gas- traps heat near Earth's surface & plays a traps heat near Earth's surface & plays a key role as “nature’s thermostat”key role as “nature’s thermostat”

Carbon: Main ProcessesCarbon: Main Processes Movement in atmosphere:Movement in atmosphere: atmos. C as CO atmos. C as CO22

(0.036% of troposphere)(0.036% of troposphere) Primary production:Primary production: photosynthesis (=carbon photosynthesis (=carbon

fixation) moves C from atmos. To organic fixation) moves C from atmos. To organic molecules in organismsmolecules in organisms

Movement through food webs:Movement through food webs: C movement C movement in organic form from organism to organismin organic form from organism to organism

Aerobic respiration:Aerobic respiration: organic molecules broken organic molecules broken down to release COdown to release CO22 back to atmos. back to atmos.

Combustion:Combustion: organic molecules broken by organic molecules broken by burning down to release COburning down to release CO22 back to atmos. back to atmos.

Dissolving in oceans:Dissolving in oceans: C enters as to form C enters as to form carbonate (COcarbonate (CO33

2-2-) and bicarbonate (HCO) and bicarbonate (HCO33--))

Movement to sediments: Movement to sediments: C enters sediments, C enters sediments, primarily as calcium carbonate (CaCOprimarily as calcium carbonate (CaCO33))

Carbon- TerrestrialCarbon- Terrestrial

Carbon- AquaticCarbon- Aquatic

Carbon Carbon cycles between the living (biotic) cycles between the living (biotic)

and non-living (abiotic) environments.and non-living (abiotic) environments.

Gaseous carbon is fixed in the process Gaseous carbon is fixed in the process

of of photosynthesisphotosynthesis and returned to the and returned to the

atmosphere in atmosphere in respirationrespiration..

Carbon may remain locked up in biotic Carbon may remain locked up in biotic

or abiotic systems for long periods of or abiotic systems for long periods of

time, e.g. in the wood of trees or in time, e.g. in the wood of trees or in

fossil fuelsfossil fuels such as coal or oil. such as coal or oil.

Humans have disturbed the balance of Humans have disturbed the balance of

the carbon cycle through activities such the carbon cycle through activities such

as combustion and deforestation.as combustion and deforestation.

Processes in Carbon CyclingProcesses in Carbon CyclingBurning fossil fuels

Petroleum

The Carbon The Carbon CycleCycle

Carbon: Human Influences?Carbon: Human Influences?

Removal of vegetation- decreases Removal of vegetation- decreases primary production (decrease carbon primary production (decrease carbon fiation)fiation)

Burning of fossil fuels & biomass (wood)- Burning of fossil fuels & biomass (wood)- increase movement of carbon into the increase movement of carbon into the atmos.atmos.

The resulting increase concentration of The resulting increase concentration of atmos. COatmos. CO22 is believed to be sufficient to is believed to be sufficient to modify world climate through global modify world climate through global warmingwarming

© 2008 John Wiley and Sons Publishers

Carbon SinkCarbon SinkUnits are PgC.- One Pg [petragram]= on ebillion metric tonnes=1000 x one bilion kg

Carbon-Silicate CycleCarbon-Silicate Cycle

The Carbon-Silicate CycleThe Carbon-Silicate Cycle

The carbon-silicate cycle:The carbon-silicate cycle:– A complex biogeochemical cycle over time A complex biogeochemical cycle over time

scales as long as one-half billion years.scales as long as one-half billion years.– Includes major geological processes, such as:Includes major geological processes, such as:

WeatheringWeathering Transport by ground and surface watersTransport by ground and surface waters ErosionErosion Deposition of crustal rocksDeposition of crustal rocks

– Believed to provide important negative Believed to provide important negative feedback mechanisms that control the feedback mechanisms that control the temperature of the atmosphere.temperature of the atmosphere.

The Archean atmosphere was a mix of gases The Archean atmosphere was a mix of gases including nitrogen, water vapor, methane including nitrogen, water vapor, methane (CH4), and CO2. (CH4), and CO2.

"Atmospheric Oxygen," free oxygen did not "Atmospheric Oxygen," free oxygen did not accumulate in the atmosphere until more accumulate in the atmosphere until more than two billion years after Earth was formed.than two billion years after Earth was formed.

Volcanoes emitted CO2 as a byproduct of Volcanoes emitted CO2 as a byproduct of heating within the Earth's crust. heating within the Earth's crust.

But instead of developing a runaway But instead of developing a runaway greenhouse effect like that on Venus, Earth's greenhouse effect like that on Venus, Earth's temperatures remained within a moderate temperatures remained within a moderate range because the carbon cycle includes a range because the carbon cycle includes a natural natural

This sink involves the weathering of silicate This sink involves the weathering of silicate rocks, such as granites and basalts, that rocks, such as granites and basalts, that make up much of Earth's crust.make up much of Earth's crust.

4 basic stages:4 basic stages:– First, rainfall scrubs CO2 out of the air, producing First, rainfall scrubs CO2 out of the air, producing

carbonic acid (H2CO3), a weak acid. carbonic acid (H2CO3), a weak acid. – Next, this solution reacts on contact with silicate rocks Next, this solution reacts on contact with silicate rocks

to release calcium and other to release calcium and other cationscations and leave behind and leave behind carbonate and biocarbonate ions dissolved in the water. carbonate and biocarbonate ions dissolved in the water. This solution is washed into the oceans by rivers, and then This solution is washed into the oceans by rivers, and then

calcium carbonate (CaCO3), also known as limestone, is calcium carbonate (CaCO3), also known as limestone, is precipitated in sediments. (Today most calcium carbonate precipitated in sediments. (Today most calcium carbonate precipitation is caused by marine organisms, which use calcium precipitation is caused by marine organisms, which use calcium carbonate to make their shells.) carbonate to make their shells.)

– Over long time scales, oceanic crust containing Over long time scales, oceanic crust containing limestone sediments is forced downward into Earth's limestone sediments is forced downward into Earth's mantle at points where plates collide, a process called mantle at points where plates collide, a process called subductionsubduction. .

– Eventually, the limestone heats up and turns the Eventually, the limestone heats up and turns the limestone back into CO2, which travels back up to the limestone back into CO2, which travels back up to the surface with magma. Volcanic activity then returns CO2 surface with magma. Volcanic activity then returns CO2 to the atmosphere.to the atmosphere.

© 2008 John Wiley and Sons Publishers

Nitrogen CycleNitrogen Cycle

Nitrogen cycleNitrogen cycle

Role of Nitrogen?Role of Nitrogen?– Building block of various essential Building block of various essential

organic molecules- especially proteins & organic molecules- especially proteins & nucleic acidsnucleic acids

– Limiting nutrient in many ecosystems- Limiting nutrient in many ecosystems- typically addition of N leads to increased typically addition of N leads to increased productivityproductivity

How is Nitrogen Cycled?How is Nitrogen Cycled?

Nitrogen Cycle: Main Nitrogen Cycle: Main ProcessesProcesses

Nitrogen fixation: Nitrogen fixation: conversion of Nconversion of N22 (nitrogen (nitrogen gas) to NHgas) to NH44

++ (ammonuim), atmospheric by (ammonuim), atmospheric by lightning, biological by bacteria & blue-green algae lightning, biological by bacteria & blue-green algae (anaerobic), e.g., Rhizobium in legumes(anaerobic), e.g., Rhizobium in legumes

Nitrification:Nitrification: conversion of NH conversion of NH44++ to NO to NO22

-- (nitrite) (nitrite) to NOto NO33

-- (nitrate) by microbes (nitrate) by microbes UptakeUptake by plants, forms proteins and other N by plants, forms proteins and other N

containing organic compounds, enters food chaincontaining organic compounds, enters food chain Ammonification:Ammonification: returned NH returned NH44

++ inorganic forms inorganic forms by saprophytes (fungi) and decomposersby saprophytes (fungi) and decomposers

Denitrification:Denitrification: conversion of NH conversion of NH44++ to N to N22 by by

combustion or microbescombustion or microbes

FUNGIFUNGI -all are heterotrophs, and eukaryotes (they contain a -all are heterotrophs, and eukaryotes (they contain a nucleus), they can be most are multi-cellular, most are nucleus), they can be most are multi-cellular, most are decomposers and feed on dead things (saprophytes). decomposers and feed on dead things (saprophytes). http://www.ucl.ac.uk/Pharmacology/dc-bits/fungi-pics1-04m.jpghttp://www.ucl.ac.uk/Pharmacology/dc-bits/fungi-pics1-04m.jpg

Nitrogen Nitrogen cycles between the biotic and abiotic environments. Bacteria cycles between the biotic and abiotic environments. Bacteria

play an important role in this transfer.play an important role in this transfer.

Nitrogen-fixing bacteriaNitrogen-fixing bacteria are able to fix atmospheric nitrogen. are able to fix atmospheric nitrogen.

Nitrifying bacteriaNitrifying bacteria convert ammonia to nitrite, and nitrite to convert ammonia to nitrite, and nitrite to

nitrate.nitrate.

Denitrifying bacteriaDenitrifying bacteria return fixed nitrogen to the atmosphere. return fixed nitrogen to the atmosphere.

Atmospheric fixation also occurs as a result of lightning discharges.Atmospheric fixation also occurs as a result of lightning discharges.

Humans intervene in the nitrogen cycle by producing and applying Humans intervene in the nitrogen cycle by producing and applying

nitrogen fertilizers.nitrogen fertilizers.

Nitrogen in the Nitrogen in the EnvironmentEnvironment

Nitrogen TransformationsNitrogen TransformationsThe ability of some bacterial species to fix The ability of some bacterial species to fix

atmospheric nitrogen or convert it between atmospheric nitrogen or convert it between

states is important to agriculture.states is important to agriculture.

Nitrogen-fixing Nitrogen-fixing species include species include RhizobiumRhizobium, which lives in a root symbiosis , which lives in a root symbiosis with leguminous plants. Legumes, such as with leguminous plants. Legumes, such as clover, beans, and peas, are commonly clover, beans, and peas, are commonly planted as part of crop rotation to restore planted as part of crop rotation to restore soil nitrogen.soil nitrogen.

Nitrifying bacteriaNitrifying bacteria include include NitrosomonasNitrosomonas and and NitrobacterNitrobacter. These bacteria convert . These bacteria convert ammonia to forms of nitrogen available to ammonia to forms of nitrogen available to plants.plants.

NH3 NO2- NO3

-

Nitrosomonas Nitrobacter

Root nodules in Acacia

Nodule close-up

Nitrogen Nitrogen CycleCycle

Nitrogen Cycle: Human Nitrogen Cycle: Human Influences?Influences?

Emit nitric oxide (NO), which leads to acid Emit nitric oxide (NO), which leads to acid rain- huge quantities of nitric oxide emitted; rain- huge quantities of nitric oxide emitted; contributes to photochemical smog; forms contributes to photochemical smog; forms nitrogen dioxide (NOnitrogen dioxide (NO22) in atmosphere, which ) in atmosphere, which can react with water to for nitric acid (HNOcan react with water to for nitric acid (HNO33) ) & cause acid deposition (“acid rain”)& cause acid deposition (“acid rain”)

Emit nitrous oxide into the atmosphere- Emit nitrous oxide into the atmosphere- nitrous oxide (Nnitrous oxide (N22O) is a potent greenhouse O) is a potent greenhouse gas & also depletes ozone in stratospheregas & also depletes ozone in stratosphere

Nitrogen Cycle: Human Influences? Nitrogen Cycle: Human Influences? (continued…)(continued…)

Mine nitrogen- containing fertilizers, deplete Mine nitrogen- containing fertilizers, deplete nitrogen from croplands, & leach nitrate from soil nitrogen from croplands, & leach nitrate from soil by irrigation- leads to modification of nitrogen by irrigation- leads to modification of nitrogen distribution in soilsdistribution in soils

Remove N from soil by burning grasslangs & Remove N from soil by burning grasslangs & cutting forest- leads to decreased N in soilscutting forest- leads to decreased N in soils

Add excess N to aquatic systems- runoff of Add excess N to aquatic systems- runoff of nirates & other soluble N- containing compounds nirates & other soluble N- containing compounds stimulates algal blooms, depletes oxygen, & stimulates algal blooms, depletes oxygen, & decreases biodiversitydecreases biodiversity

Add excess N to terrestrial systems- atmospheric Add excess N to terrestrial systems- atmospheric deposition increase growth of some species deposition increase growth of some species (especially weeds) & can decrease biodiversity(especially weeds) & can decrease biodiversity

Phosphorous CyclePhosphorous Cycle

Role of Phosphorous?Role of Phosphorous?– Essential nutrient for plants & animals:Essential nutrient for plants & animals:

especially building block for DNA, other especially building block for DNA, other nucleic acids (including ATP; ATP stores nucleic acids (including ATP; ATP stores chemical energy), various fats in cell chemical energy), various fats in cell membrane (phospholipids), & hard calcium-membrane (phospholipids), & hard calcium-phosphate compounds (in bone, teeth, & phosphate compounds (in bone, teeth, & shells)shells)

– Limiting nutrient in many ecosystems-Limiting nutrient in many ecosystems- typically, addition of P leads to increased typically, addition of P leads to increased productivity, especially for fresh water productivity, especially for fresh water aquatic systemsaquatic systems

Phosphorus cyclingPhosphorus cycling is very slow and is very slow and

tends to be local; in aquatic and terrestrial tends to be local; in aquatic and terrestrial

ecosystems, it cycles through food webs.ecosystems, it cycles through food webs.

Phosphorous is lost from ecosystems Phosphorous is lost from ecosystems through run-off, precipitation, and through run-off, precipitation, and sedimentation.sedimentation.

A very small amount of phosphorus A very small amount of phosphorus returns to the land as returns to the land as guanoguano (manure, (manure, typically of fish-eating birds). typically of fish-eating birds). Weathering and Weathering and phosphatizing phosphatizing bacteriabacteria return phosphorus to the soil. return phosphorus to the soil.

Human activity can result in excess Human activity can result in excess phosphorus entering water ways and is phosphorus entering water ways and is a major contributor to a major contributor to eutrophicationeutrophication. .

Phosphorus CyclingPhosphorus Cycling

Deposition as guano…

Loss via sedimentation…

Fertilizer production

Phosphorous: Main Phosphorous: Main ProcessesProcesses

Weathering:Weathering: P slowly released from rock or P slowly released from rock or soil minerals as phosphate (POsoil minerals as phosphate (PO44

3-3-), which ), which dissolves in Hdissolves in H22O & is readily leachedO & is readily leached

Uptake:Uptake: by plants to form organic phosphates by plants to form organic phosphates Movement through food web:Movement through food web: nucleic acids nucleic acids

(including DNA 7 ATP), certain fats in cell (including DNA 7 ATP), certain fats in cell membranes (phospholipids), bones/teeth/shells membranes (phospholipids), bones/teeth/shells (calcium-phosphate)(calcium-phosphate)

Break down of organic forms:Break down of organic forms: to phosphate to phosphate (PO(PO44

3030) by decomposers) by decomposers Leaching:Leaching: PO PO44

3-3- from soil from soil Burial in ocean sediments:Burial in ocean sediments: not cycled in not cycled in

short time scale, only over geologic timeshort time scale, only over geologic time

The Phosphorus The Phosphorus CycleCycle

Guano deposits

Phosphorous: Human Phosphorous: Human Influences?Influences?

Mine large quantities of phosphate rock:Mine large quantities of phosphate rock: used for organic fertilizers & detergents; can used for organic fertilizers & detergents; can cause local environmental effects from cause local environmental effects from mining & releases more P into environementmining & releases more P into environement

Sharply decrease P available in tropical Sharply decrease P available in tropical forests & other ecosystems where P is forests & other ecosystems where P is limiting:limiting: deforestation & certain agricultural deforestation & certain agricultural practices decrease available Ppractices decrease available P

Add excess P to aquatic ecosystems:Add excess P to aquatic ecosystems: leads to excessive algal growth, depletion of leads to excessive algal growth, depletion of oxygen, & decrease in biodiversity; such oxygen, & decrease in biodiversity; such eutrophication (“over nourishment”) will be eutrophication (“over nourishment”) will be discussed laterdiscussed later

Sulfur CycleSulfur Cycle

Sulfur CycleSulfur Cycle

Role of Sulfur?Role of Sulfur?– Component of some proteins & vitamins:Component of some proteins & vitamins:

essential for organismsessential for organisms– Limiting nutrient in some ecosystemsLimiting nutrient in some ecosystems

Sulfur Cycle: Main ProcessesSulfur Cycle: Main Processes Storage in rocks:Storage in rocks: much of Earth’s S is in rock much of Earth’s S is in rock

form (e.g., iron disulfides or pyrites) or minerals form (e.g., iron disulfides or pyrites) or minerals (sulfates)(sulfates)

Atmospheric input from volcanoes, Atmospheric input from volcanoes, anaerobic decay, & sea spray:anaerobic decay, & sea spray: S enters S enters atmosphere in form of hydrogen sulfide (HS), atmosphere in form of hydrogen sulfide (HS), sulfur dioxide (SOsulfur dioxide (SO22), and sulfates (S)), and sulfates (S)44

2-2-)) Combustion:Combustion: sulfur compounds released to the sulfur compounds released to the

atmosphere by oil refining, burining of fossil atmosphere by oil refining, burining of fossil fuels, smelting, and various industrial activitiesfuels, smelting, and various industrial activities

Movement through food web:Movement through food web: movement movement through foor web & eventual release during through foor web & eventual release during decaydecay

Biotic flow of sulfur through Biotic flow of sulfur through ecoystemsecoystems

Abiotic flow of sulfur through Abiotic flow of sulfur through ecosystemsecosystems

Sulfur Cycle: Human Sulfur Cycle: Human Influences?Influences?

Contribute about 1/3 of Contribute about 1/3 of atmospheric sulfur emissions:atmospheric sulfur emissions:– Burning S- containing oil and coalBurning S- containing oil and coal– Refining petroleumRefining petroleum– SmeltingSmelting– Other industrial processesOther industrial processes

Rock CycleRock Cycle