BIO220H1 Lecture Notes - Lecture 9: Seabird, Eutrophication, Rhizobium
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BIO220H1 Full Course Notes
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Document Summary
Nuclear weapons used by us and ussr after cold war. Radioactive tracers allowed following fates of chemicals in natural communities. E. g. , manhattan project: classic model for collaborative big science , a model that ecologists tried to follow with limited success. Nitrogen cycle: gaseous cycle, human intervention: n fertilizer for crops. Phosphorus cycle: sedimentary cycle, human interventions: mining, pollution. Hydrological cycle pools and fluxes: human intervention: freshwater diversion for agriculture. Large organic molecules are constantly being synthesized, consumed, and broken down: food and decomposer webs. Chemical elements are not created or destroyed but they do move around (and change oxidation states: cycling: moving around. Stable, long-lived compounds (e. g. , water and some pollutants) can persist much as elements do: phase changes may be important. N and p are two elements most likely to limit plant productivity carbon cycle subsumes trophic webs. Much c in organisms: food chains. Limiting steps involve balance between creation (by photosynthesis) and respiration/combustion of organic matter.
