Disc8_22Mar - Forms • S elemental sulfur • S 2-sulfide...

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CEE 320 Discussion 8 22-Mar-10 1 Nitrogen cycle Forms: N 2 nitrogen gas NH 3 ammonia NO 2 - nitrite NO 3 - nitrate Organic-N (C x H y O z N q ) Reactions: Nitrification - done by nitrifying bacteria ( Nitrosomonas, Nitrobacter ) NH 3 + O 2 NO 2 NO 3 Denitrification - done by denitrifying bacteria ( Pseudomonas ) NO 3 NO 2 N 2 O N 2 Nitrogen fixation - done by nitrogen-fixing bacteria ( Rhizobium, Bradyrhizobium ) N 2 energy ί ί ί NH 3 Decomposition organic N NH 3 How do humans impact the nitrogen cycle? Runoff Atmospheric deposition Phosphorus cycle Forms: H 3 PO 4 phosphoric acid H 2 PO 4 - dihydrogen phosphate HPO 4 - hydrogen phosphate PO 4 3- phosphate Organic-P (C x H y O z N q P f ) Reactions: Precipitation/dissolution Acid/base organic inorganic How do humans impact the phosphorus cycle? Runoff - think about Lake Mendota! Sulfur cycle
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Unformatted text preview: Forms: • S elemental sulfur • S 2-sulfide • SO 4 2-sulfate • Organic-S (C x H y O z N q P f S) Reactions: (all reactions are microbially-mediated) • Sulfur oxidation - occurs in hot springs, acid mine drainage S → SO 4 2 − CEE 320 Discussion 8 22-Mar-10 2 • Sulfate reduction - occurs under anoxic conditions (e.g. sewers, bottom of lakes) SO 4 2 − → S 2 − + 2H + ί → ί ί H 2 S (g) • Sulfide oxidation - often occurs where sulfur oxidation is also occuring S 2 − → S → SO 4 2 − • Organic-S synthesis and decomposition Productivity Oligotrophic: low productivity. Mesotrophic: medium productivity; between eutrophic and oligotrophic. Eutrophic: high productivity, does not have to be anthropogenic....
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This note was uploaded on 05/04/2010 for the course CEE 320 taught by Professor Mcmahon during the Spring '10 term at University of Wisconsin.

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Disc8_22Mar - Forms • S elemental sulfur • S 2-sulfide...

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