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Biogeochemical Cycling – Fall 2010

Biogeochemical Cycling – Fall 2010. Theme Modern Changes in the Nitrogen Cycle. Friday Discussion Group Discussion Leader: Priya Ganguli 12 November, 2010. N 5 th most abundant element in solar system Essential for synthesis of nucleic acids and proteins

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Biogeochemical Cycling – Fall 2010

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  1. Biogeochemical Cycling – Fall 2010 Theme Modern Changes in the Nitrogen Cycle Friday Discussion Group Discussion Leader: Priya Ganguli 12 November, 2010

  2. N 5th most abundant element in solar system • Essential for synthesis of nucleic acids and proteins • For every 100 atoms of C in cells, need 2 to 20 atoms of N • Biogeochemistry of N primarily oxidation-reduction and microbially mediated • Secondarily influenced by long-term cycling through geosphere • N2 largely unavailable to organisms • NO3- and HN4+ (fixed forms) often limit primary productivity in both marine & terrestrial ecosystems

  3. Nitrogen Fixation prokaryotes in bacterial and archaeal domains reduce N2 gas to ammonium ion (NH4+)

  4. nitrate (NO3-) reduction coupled to anaerobic oxidation of Corg • N2 gas • (denitrification) • or • NH4+ • (dissimilatory nitrate reduction to ammonium) (DNRA) electron acceptors from Baker MA, Dahm CN, Valett HM, 2000

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