Publication Date:
2022-05-26
Description:
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of AAAS for personal use, not for redistribution. The definitive version was published in Science 348 (2015): 428-431, doi:10.1126/science.aaa4326.
Description:
Methane is a key component in the global carbon cycle with a wide range of anthropogenic and natural
sources. Although isotopic compositions of methane have traditionally aided source identification, the
abundance of its multiply-substituted “clumped” isotopologues, e.g., 13CH3D, has recently emerged as a
proxy for determining methane-formation temperatures; however, the impact of biological processes on
methane’s clumped isotopologue signature is poorly constrained. We show that methanogenesis
proceeding at relatively high rates in cattle, surface environments, and laboratory cultures exerts kinetic
control on 13CH3D abundances and results in anomalously elevated formation temperature estimates. We
demonstrate quantitatively that H2 availability accounts for this effect. Clumped methane thermometry
can therefore provide constraints on the generation of methane in diverse settings, including continental
serpentinization sites and ancient, deep groundwaters.
Description:
Grants from the National Science Foundation (EAR-
1250394 to S.O. and EAR-1322805 to J.C.M.), N. Braunsdorf and D. Smit of Shell PTI/EG (to S.O.), the
Deep Carbon Observatory (to S.O., B.S.L., M.K., and K.-U.H.), the Natural Sciences and Engineering
Research Council of Canada (to B.S.L.), and the Gottfried Wilhelm Leibniz Program of the Deutsche
Forschungsgemeinschaft (HI 616-14-1 to K.-U.H. and M.K.) supported this study. D.T.W. was supported
by a National Defense Science and Engineering Graduate Fellowship. D.S.G. was supported by the Neil
and Anna Rasmussen Foundation Fund, the Grayce B. Kerr Fellowship, and a Shell-MITEI Graduate
Fellowship.
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
