Other Biogeochemical Cycles

Other Biogeochemical Cycles - used as foods by larger...

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Other Biogeochemical Cycles In addition to being a site for the nitrogen cycle, the soil is the environment in which several other  biogeochemical cycles take place. Among these are the cycles of phosphorus, sulfur, carbon, and  oxygen. The phosphorus cycle.  Living things use  phosphorus  compounds in the synthesis of nucleotides,  phospholipids, and phosphorylated proteins. Phosphorus enters the soil and water as phosphate  ions, such as calcium phosphate, during the breakdown of crops, decaying garbage, leaf litter, and  other sources.  In the  phosphorus cycle , microorganisms use phosphorus in the form of calcium phosphate,  magnesium phosphate, and iron phosphate. They release the phosphorus from these complexes  and assimilate the phosphorus as the phosphate ion (PO 4 ). This ion is incorporated into DNA, RNA,  and other organic compounds using phosphate, including phospholipids. When the organisms are 
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Unformatted text preview: used as foods by larger organisms, the phosphorus enters and is concentrated in the food chain. The sulfur cycle. Sulfur makes up a small percentage of the dry weight of a cell (approximately 1 percent), but it is an important element in the formation of certain amino acids such as cystine, methionine, and glutathione. It is also used in the formation of many enzymes. Many bacteria have an important place in the sulfur cycle in the soil. Sulfate-reducing bacteria grow in mud and anaerobic water environments, where they reduce sulfur-containing amino acids to hydrogen sulfide (H 2 S). Hydrogen sulfide accumulates in the mud of a swamp and gives the environment an odor of rotten eggs....
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