Methane anaerobic oxidation

Schouten S, SG Wakeham, EC Hopmans, JSS Damste (2003) Biogeochemical evidence that thermophilic archaea mediate the anaerobic oxidation of methane. Appl Environ Microbiol 69 1680-1686. 

These redox reactions are abiogenic, whereas the methane sinks are thought to be biogenic, such as the anaerobic oxidation of methane by archaea as observed at the Lost City vent fields (Figure 19.20). Microbial production of methane has also been observed at this site. 

The anaerobic oxidative coupling of methane to ethylene was studied by ARCO Chemical [70b]. The reaction occurs at a very high temperature of 850-900 °C with a Li/B/Mn/Mg/0-Si02 catalyst, a conversion of 22% was achieved with selectivity to C2 compounds of about 60% under anaerobic conditions. Monsanto [71] studied... 

That source appears to be quite small. While methane is certainly produced by microbes in oxygen-poor and anaerobic regions of the ocean, in order for the methane to escape to the atmosphere it must first pass through an overlying layer in the ocean with abundant oxygen. Probably the methane is oxidized by aerobic microbes in these layers before it can escape. 

Strous, M., andjetten, M. S. M. (2004). Anaerobic Oxidation of Methane and Ammonium. Annual Review of Microbiology. 58, 99-117. 

Anaerobic CH4 oxidation, now referred to as anaerobic oxidation of methane (AOM), has received renewed attention with introduction of new organic geochemical and molecular techniques. Hinrichs et al. (1999) applied compound-specific isotope analyses of lipid biomarker molecules associated with specific archea and culture-independent techniques involving 16S rRNA identification studies to samples collected from an Eel River Basin seep. This work showed that the biomarker compounds were so strongly depleted in that CH4 must be the source rather... 

Boetius A., Ravenschlag K., Schubert C. J., Rickert D., Widdel F., Gieseke A., Amann R., Jprgensen B. B., Witte U., and Pfankuche O. (2000) A marine microbial consortium apparently mediating anaerobic oxidation of methane. Nature 407, 623-626. 

Nauhaus K., Boetius A., Kruger M., and Widdel E. (2002) In vitro demonstration of anaerobic oxidation of methane coupled to sulfate reduction in sediment from a marine gas hydrate area. Environ. Microbiol. 4, 296—305. 

A second newly recognized group of prokaryotes are the methane oxidizing archea. Nearly 90% of the methane produced in anoxic marine sediments is recycled through anaerobic microbial oxidation processes (Cicerone and Oremland, 1988 Reeburgh et al., 1991). However, the organisms and biochemical processes responsible for the anaerobic oxidation of methane (AMO)... 

Bian E., Hinrichs K.-U., Xie T., Brassell S. C., Iversen N., Eossing H., Jprgensen B. B., Sylva S. P., and Hayes J. M. (2001) Algal and archaeal polyisoprenoids in a recent marine sediment molecular isotopic evidence for anaerobic oxidation of methane. Geochem. Geophys. Geosys. 2, 2000GC000112. 

Figure 12 Major reduction-oxidation reactions involving nitrogen. The reactions are numbered as follows (1) mineralization, (2) ammonium assimilation, (3) nitrification, (4) assimilatory or dissimilatory nitrate reduction, (5) ammonium oxidation, (6) nitrite oxidation, (7) assimilatory or dissimilatory nitrate reduction, (8) assimilatory or dissimilatory nitrite reduction, (9) denitrification, (10) chemodenitrification, (11) anaerobic ammonium oxidation, and (12) dinitrogen fixation (after Capone, 1991) (reproduced by permission of ASM Press from Microbial Production and Consumption of Greenhouse Gases Methane, Nitrogen Oxides, and Halomethanes, 1991).

Murase J. and Kimura M. (1994a) Methane production and its fate in paddy fields 6. Anaerobic oxidation of methane in plow layer soil. Soil Sci. Plant Nutr. 40, 505-514. 

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