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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
© 2008 John Wiley and Sons Publishers
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)
© 2008 John Wiley and Sons Publishers
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…
© 2008 John Wiley and Sons Publishers
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