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Unformatted text preview: o Oceans contain 97% of water in the biosphere o Only 1% of freshwater is available o Evaporation, condensation, precipitation controls this cycle • Carbon o “Balance of CO 2 uptake (photosynthesis) and CO 2 release (respiration) by biosphere o Human inputs are increasing atmospheric CO 2 levels o Majority of carbon stocks are not accessible to living organisms o Anthropogenic contributions have altered the carbon cycle • Nitrogen o Major fluxes: o Inputs: Atmospheric deposition N-fixation o Outputs: Dentrification Leaching o Internal cycling: Accounts for most plant demand on an annual basis • Phosphorus o Major fluxes: o Inputs: No atmospheric input Weathering of rocks o Outputs Leaching Sedimentation o Internal cycling Locally among soil, plants, and consumers...
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- Spring '07
- Biogeochemical Cycling, Biogeochemical Cycling Biogeochemical, nutrient cycling Dynamics, biosphere Human inputs