Unformatted text preview: liberated by ammonification NH4 is o d ed to p oduces NO3 s oxidized produces O3 Denitrifyers reduce NO3 to N2 N2 converted into NH4 by nitrogen fixers Includes cyanobacteria!!! NH4 and NO3 are used by bacteria and plants to synthesize amino acids • Bi Bioremediation di ti NITROGEN TRANSFORMATIONS
• Two important transformations: - Nitrogen Fixation
N2 NH3 - D it ifi ti Denitrification
NO2 or NO3 N2 • Both are microbially mediated NITROGEN TRANSFORMATIONS
• Other transformation: - Nitrification
NH4 NO3 • Also microbially mediated Anaerobic PHOSPHORUS
• • • • No gas phase Rocks ultimate source Only present as phosphate (PO4) Largely a one-way trip
- Weathering Sediments Rivers Oceans • Unique role of marine birds and their guano Often limiting in freshwaters g • Unique role of bacteria in microbial loop , , , , • Needed for DNA, ATP, bones, teeth, shells What happens in estuaries???
• Role of rivers and nutrient loading
- Dissolved versus particulate - Inorganic versus organic • Abiotic and biotic processing as you move downstream • Aerobic versus anaerobic environment - Oxidation/Reduction, Electron acceptors - Differences f N and P availability ff for d l bl...
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- Spring '08
- Global Biogeochemical Cycles