BIO220H1 Lecture Notes - Lecture 9: Eutrophication, Nitrification, Bacteria
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BIO220H1 Full Course Notes
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Us national labs researched radiation effects on organisms & ecosystems. Nuclear research also gave ecology tools and a model. Radioactive tracers allowed following fates of chemicals in natural communities (radio isotopes that can be followed through ecosystem) N cycle: a gaseous cycle human intervention: n fertilizer for crops. P cycle: a sedimentary cycle human interventions: mining, pollution. Chemical elements aren"t created or destroyed, but they do move around = cycling. Cycle comprises pools and fluxes (transitions between different pools) All tied to hydrologic cycle c cycle subsumes trophic webs. N and p are the 2 elements most likely to limit plant productivity. N cycle mostly gaseous, compounds highly soluble, minimal sedimentary pools converting n2 gas (plant can not use), into usable nitrate or ammonium human: combustion of fuels, use of energy to make synthetic fertilizers. N fixation reduces n2 to nh3 requires a lot of energy, in nature mostly done by eubacteria, cyanobacteria, lightening (especially rhizobium and legume plants)