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Biogeochemical Nitrogen Cycle

Biogeochemical Nitrogen Cycle. By Patrick Greenwood & Tyler Morris. Key Concepts. The nitrogen cycle is the set of biogeochemical processes by which nitrogen undergoes chemical reactions, changes form, and moves through difference reservoirs on earth, including living organisms.

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Biogeochemical Nitrogen Cycle

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  1. Biogeochemical Nitrogen Cycle By Patrick Greenwood& Tyler Morris

  2. Key Concepts • The nitrogen cycle is the set of biogeochemical processes by which nitrogen undergoes chemical reactions, changes form, and moves through difference reservoirs on earth, including living organisms. • Nitrogen is required for all organisms to live and grow because it is the essential component of DNA, RNA, and protein. However, most organisms cannot use atmospheric nitrogen, the largest reservoir. • The five processes in the nitrogen cycle -- fixation, uptake, mineralization, nitrification, and denitrification-- are all driven by microorganisms. • Humans influence the global nitrogen cycle primarily through the use of nitrogen-based fertilizers.

  3. Definitions • Nitrogen fixation - N2 →NH4+Nitrogen fixation is the process wherein N2 is converted to ammonium, essential because it is the only way that organisms can attain nitrogen directly from the atmosphere. • Nitrogen uptake - NH4+→ Organic N The ammonia produced by nitrogen fixing bacteria is usually quickly incorporated into protein and other organic nitrogen compounds, either by a host plant, the bacteria itself, or another soil organism. • Nitrogen mineralization - Organic N →NH4+ After nitrogen is incorporated into organic matter, it is often converted back into inorganic nitrogen by a process called nitrogen mineralization, otherwise known as decay. When organisms die, decomposers (such as bacteria and fungi) consume the organic matter and lead to the process of decomposition.

  4. More Definitions • Nitrification - NH4+ → NO3-Some of the ammonium produced by decomposition is converted to nitrate via a process called nitrification. The bacteria that carry out this reaction gain energy from it. • Denitrification - NO3-N2+ N2O Through denitrification, oxidized forms of nitrogen such as nitrate and nitrite (NO2-) are converted to dinitrogen (N2) and, to a lesser extent, nitrous oxide gas. • Leaching - Like the negative end of a magnet, nitrogen in the form of nitrate is negatively charged and is not attracted to soil's negatively charged clay and humus. Negatively charged clay repels negatively charged nitrite ( NO2- ) and nitrate ( NO3- ) so they will not be absorbed by the clay and are left to move down through the soil and into the groundwater, where streams and drinking water can become contaminated. • Volatilization- Nitrogen in the form of a gas (such as NH3, NO, N20, or N2) is moved out of soil and into the Earth's atmosphere.

  5. Bibliography •  "NFT Game." Soil Science Education Home Page. Web. 20 Nov. 2010. <http://soil.gsfc.nasa.gov/NFTG/nitrocyc.htm>. • Comparison, By. "The Nitrogen Cycle." Visionlearning. Web. 20 Nov. 2010. <http://www.visionlearning.com/library/module_viewer.php?mid=98>. • "The Nitrogen Cycle." Windows to the Universe. Web. 20 Nov. 2010. <http://www.windows2universe.org/earth/Life/nitrogen_cycle.html>.

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