BIOA02H3 Chapter Notes - Chapter 49.3: Eutrophication, Surface Runoff, Cyanobacteria
26 Mar 2017
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49. 3: human influence on the nitrogen and phosphorus cycles. We in uence the environment because we are an important part of the carbon cycle. Since we want to improve crop production, we also impact the n and p cycles. Nitrogen fertilizer transported to lakes and the sea causes eutrophication. All organisms need n to make proteins, nucleic acids, and other molecules. N is plentiful in the atmosphere but it"s not biologically available to animals and plants. N- xing bacteria and archaeons convert it to xed n, such as ammonia and nitrate, that is biologically available. Since crops are harvested in the same elds yearly, they deplete the available n and farmers have to add biologically available n to the soil as fertilizer. By using fertilizer, humans add lots of xed n to the biosphere and this is created by reacting n2 and h2 in the presence of a catalyst to produce ammonia and further processed to nitrate.
