Exchange catalysis during anaerobic methanotrophy revealed by 12CH2D2 and 13CH3D in methane
Publication date
2019-04-15
Authors
Ash, Jeanine
Egger, M.J.
Treude, T.
Kohl, I.
Cragg, B.
Parkes, R.J.
Slomp, Caroline
Sherwood Lollar, B.
Young, E.D.
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Document Type
Letter
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Abstract
The anaerobic oxidation of methane (AOM) is a crucial component of the methane cycle, but quantifying its role in situ under dynamic environmental conditions remains challenging. We use sediment samples collected during IODP Expedition 347 to the Baltic Sea to show that relative abundances of 12CH2D2 and 13CH3D in methane remaining after microbial oxidation are in internal, thermodynamic isotopic equilibrium, and we attribute this phenomenon to the reversibility of the initial step of AOM. These data suggest that 12CH2D2 and 13CH3D together can identify the influence of anaerobic methanotrophy in environments where conventional bulk isotope ratios are ambiguous, and these findings may lead to new insights regarding the global significance of enzymatic back reaction in the methane cycle.
Keywords
methane, clumped isotopes, anaerobic methanotrophy, deep biosphere, Integrated Ocean Drilling Program Exp. 347
Citation
Ash, J, Egger, M, Treude, T, Kohl, I, Cragg, B, Parkes, R J, Slomp, C, Sherwood Lollar, B & Young, E D 2019, 'Exchange catalysis during anaerobic methanotrophy revealed by 12 CH 2 D 2 and 13 CH 3 D in methane', Geochemical perspectives letters, vol. 10, pp. 26-30. https://doi.org/10.7185/geochemlet.1910