4-24-08 notes

4-24-08 notes - o Oceans contain 97% of water in the...

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4/24/2008 Energy Flow and nutrient cycling Dynamics of ecosystems involve two processes: 1) Energy flow a. All the organisms living in a community and the abiotic factors in which they interact b. Unlimitedly dissipated as heat c. Energy conversion is not completely efficient—some energy is always lost as heat in any convergence process 2) Nutrient cycling a. Nutrients are constantly recycled Biogeochemical Cycling Biogeochemical cycling: the movement of chemical elements or molecules through the abiotic and biotic parts of the ecosystem Life depends on recycling essential elements o C, N, P, water, etc. Two general categories for biogeochemical cycling: global and local 1) Global a. Gaseous forms b. Carbon, oxygen, sulfur, nitrogen 2) Local a. Less mobile elements b. Phosphorus, potassium, calcium Water
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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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4-24-08 notes - o Oceans contain 97% of water in the...

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