Nov 5_ESM219_07

Nov 5_ESM219_07 - ESM 219 Nov 5th S Fe Hg cycles and...

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ESM 219 Nov 5 th : S, Fe, Hg cycles and microbes
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Microbes in the S cycle
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The global balance of sulfur. Artificial emissions are derived from human activities. An asterisk indicates a process that is partially or solely due to microbial action.
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NOTE: Biological and chemical S cycling are at similar rates. DMSO= dimethyl sulfoxide DMS = dimethyl sulfide
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Sulfur and sulfide oxidation sulfur oxidation (autrophic or heterotrophic) Lowers pH Thiobacillus are everywhere Beggiatoa mixotroph: organic cmpd for C, H 2 S for energy • Oxidation reactions (can involve NO 3 - ) S o + 3/2 O 2 + H 2 O H 2 SO 4 -587 kJ/rxn H 2 S + 2O 2 SO 4 2- + 2H + -798.2 kJ/rxn HS- + ½ O 2 + H + S o + H 2 O -209.4 kJ/rxn S 2 O 3 2- +H 2 O+2O 2 2SO 4 2- +2H + -822.6 kJ/rxn
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Fates of DMS atmosphere release then photochemical oxidation in anoxic sys. is a substrate for methanogens e - donor to phototrophs yielding DMSO e - donor for chemolithotrophs or autotrophs
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Attachment of the sulfur-oxidizing archaeon Sulfolobus acidocaldarius to a crystal of elemental sulfur. Cells are visualized by fluorescence microscopy after staining the cells with the dye acridine orange. The sulfur crystal does not fluoresce.
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Deposition of internal sulfur granules by  Beggiatoa.
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Sulfur and sulfate reduction Elemental sulfur can be reduced ( Archaeal ) Sulfate reduction to hydrogen sulfide – SO 4 2- + 8H H 2 S + 2H 2 O + 2OH - Organic C oxidized, sulfate = e - acceptor – Some can oxidize H 2 and acetate • K s for H 2 6.6 μ M for methanogens 1.3 μ M for sulfate reducers • K s for acetate 3 mM for methanogens 0.2 mM for sulfate reducers
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This note was uploaded on 08/06/2008 for the course ESM 219 taught by Professor Holden during the Fall '07 term at UCSB.

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Nov 5_ESM219_07 - ESM 219 Nov 5th S Fe Hg cycles and...

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