ecosystems : cycles

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ECOSYSTEMSECOSYSTEMS::CyclesCycles

www.swpc.noaa.gov/


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

http://upload.wikimedia.org/wikipedia/commons/thumb/2/21/CNO_Cycle.svg/300px-CNO_Cycle.svg.png


http://www.kidsgeo.com/images/carbon-cycle.gif


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.



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



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

http://www.mii.org/Minerals/Minpics1/CoalAnthracite.jpg



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

http://www.ust.hk/~webpepa/pepa/ways_of_protection/air_general.JPG


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..

http://www.palacesandtigers.com/images/gallery/sri_lanka/Vil%20Uyana%20rice%20paddy.jpg


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

www.rps.psu.edu


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


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

http://www.thisland.uiuc.edu/50ways/images/5b.jpg


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


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.

http://www.tampagov.net/dept_Wastewater/information_resources/Advanced_Wastewater_Treatment_Plant/Virtual_Tour/images/denit_filter.jpg


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

http://content.answers.com/main/content/wp/en/thumb/b/b9/180px-PhosphateRockUSGOV.jpg


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


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

ecosystems : cycles

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