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ECOSYSTEMSECOSYSTEMS::CyclesCycles
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Biochemical CyclingBiochemical Cycling
Cycling of nutrients called Cycling of nutrients called biogeochemical cyclingbiogeochemical cycling
Move nutrients from nonliving world Move nutrients from nonliving world to living organisms and back.to living organisms and back.
Without recycling, life could not existWithout recycling, life could not exist Four biogeochemical cyclesFour biogeochemical cycles
– CarbonCarbon - Nitrogen- Nitrogen– OxygenOxygen - Phosphorus- Phosphorus
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Carbon CyclingCarbon Cycling
Photosynthesis – removes carbon dioxide Photosynthesis – removes carbon dioxide from the atmosphere and turns it into from the atmosphere and turns it into biomass.biomass.
Respiration – returns carbon dioxide to the Respiration – returns carbon dioxide to the atmosphere when food is burned by cells.atmosphere when food is burned by cells.
Carbon is also returned to the Carbon is also returned to the environment when an organism dies environment when an organism dies through the action of detrivores.through the action of detrivores.
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Carbon CyclingCarbon Cycling
Some organisms die and accumulate.Some organisms die and accumulate. Forms large layers of limestone rockForms large layers of limestone rock
– Store carbon in rocks for Store carbon in rocks for millions yearsmillions years Known as carbon reservoirKnown as carbon reservoir Weathering returns carbon Weathering returns carbon
into atmosphereinto atmosphere Volcanic eruptions add Volcanic eruptions add
carbon dioxide to carbon dioxide to atmosphereatmosphere
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Carbon CyclingCarbon Cycling
Alternate path—plants and animals are buriedAlternate path—plants and animals are buried
Exposed to heat and pressure beneath Exposed to heat and pressure beneath
Earth’s surfaceEarth’s surface
Causes chemical changesCauses chemical changes
Produces fossil fuels—oil and coalProduces fossil fuels—oil and coal– Oil—once living planktonOil—once living plankton– Coal—remains of plants buried in swampsCoal—remains of plants buried in swamps
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Carbon CyclingCarbon Cycling
Fossil fuels known as hydrocarbonsFossil fuels known as hydrocarbons Composed of hydrogen and carbonComposed of hydrogen and carbon
Burning returns to atmosphere as carbon dioxideBurning returns to atmosphere as carbon dioxide
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Carbon CyclingCarbon Cycling Creation of methane gas (CH4)Creation of methane gas (CH4)
Mud of rice paddies in AsiaMud of rice paddies in Asia– Anaerobic bacteria release methane gasAnaerobic bacteria release methane gas
Cows produce methane in their digestive Cows produce methane in their digestive
systemssystems..
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Oxygen CyclingOxygen Cycling
One of most important interactionsOne of most important interactions– Photosynthesis and respiration reactionsPhotosynthesis and respiration reactions– Photosynthesis consumes carbon dioxide and Photosynthesis consumes carbon dioxide and
releases oxygenreleases oxygen
Used during respiration and Used during respiration and carbon dioxide is released carbon dioxide is released
– Vital link between plants and Vital link between plants and animals on Earthanimals on Earth
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Oxygen CyclingOxygen Cycling
The Earth’s crust is also a reservoir for oxygen The Earth’s crust is also a reservoir for oxygen storage.storage.
http://lasp.colorado.edu/~bagenal/3720/CLASS21/CO2cycle.jpg
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Nitrogen Cycling - NitrificationNitrogen Cycling - Nitrification
Begins with bacteria in soil and rootsBegins with bacteria in soil and roots Combine ammonia with other atomsCombine ammonia with other atoms Nitrogen compounds absorbed by roots of Nitrogen compounds absorbed by roots of
plantsplants Used to make proteinsUsed to make proteins
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Nitrogen Cycling Nitrogen Cycling - Nitrogen Fixation - Nitrogen Fixation
Legumes harbor bacteria that fix nitrogen in small Legumes harbor bacteria that fix nitrogen in small nodules in their roots.nodules in their roots.
Convert atmospheric nitrogen to plant-available Convert atmospheric nitrogen to plant-available nitrogennitrogen
Used to form proteins and other Used to form proteins and other compounds, which makes compounds, which makes nitrogen available to other nitrogen available to other organismsorganisms
http://overton.tamu.edu/clover/cool/NodCrimW.jpg
Nodules on Clover roots
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Nitrogen Cycling - DenitrificationNitrogen Cycling - Denitrification
Bacteria in the soil Bacteria in the soil break down dead break down dead organisms, organisms, releasing nitrogen releasing nitrogen gas into the gas into the atmosphereatmosphere..
Denitrification filter,part of wastewater treatment plant.
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Phosphorus CyclingPhosphorus Cycling
Major source of phosphorus is not the atmosphereMajor source of phosphorus is not the atmosphere– Found in rocksFound in rocks
Phosphate-containing rocks become weathered Phosphate-containing rocks become weathered (break down)(break down)
Main source of phosphorus for ecosystems of Main source of phosphorus for ecosystems of EarthEarth
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Phosphorus CyclingPhosphorus Cycling Animal wastes contain large amounts of Animal wastes contain large amounts of
phosphorusphosphorus
Helps to recycle back through food chainHelps to recycle back through food chain
Rare in some ecosystemsRare in some ecosystems– Called a limiting factorCalled a limiting factor
http://www.gardening.cornell.edu/lawn/almanac/images/fertilizer3.gif
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Phosphorus CyclingPhosphorus Cycling
Human activity raises phosphorus levelsHuman activity raises phosphorus levels– Waste disposal and use of fertilizerWaste disposal and use of fertilizer
Causes rapid growth in aquatic plants and algaeCauses rapid growth in aquatic plants and algae
http://www.waterencyclopedia.com/images/wsci_01_img0017.jpg
Result is algae bloomResult is algae bloomChokes waterway with overgrowthChokes waterway with overgrowth