Nonequilibrium clumped isotope signals in microbial methane

• Main Authors: Wang, David T. (Contributor), Gruen, Danielle Sarah (Contributor), Lollar, Barbara Sherwood (Author), Hinrichs, Kai-Uwe (Author), Stewart, Lucy C. (Author), Holden, James F. (Author), Hristov, Alexander N. (Author), Pohlman, John W. (Author), Morrill, Penny L. (Author), Könneke, Martin (Author), Delwiche, Kyle Brook (Contributor), Reeves, Eoghan (Contributor), Sutcliffe, Chelsea N. (Author), Ritter, Daniel J. (Author), Seewald, Jeffrey S. (Author), McIntosh, Jennifer C. (Author), Hemond, Harold F. (Contributor), Kubo, Michael D. (Author), Cardace, Dawn (Author), Hoehler, Tori M. (Author), Ono, Shuhei (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Civil and Environmental Engineering (Contributor), Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences (Contributor)
• Format: Article
• Language: English
• Published: American Association for the Advancement of Science (AAAS), 2015-03-06T15:14:39Z.
• Subjects: Article
• Online Access: Get fulltext

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.
National Science Foundation (U.S.) (EAR-1250394)
National Science Foundation (U.S.) (EAR-1322805)
Deep Carbon Observatory (Program)
Natural Sciences and Engineering Research Council of Canada
Deutsche Forschungsgemeinschaft (Gottfried Wilhelm Leibniz Program)
United States. Dept. of Defense (National Defense Science and Engineering Graduate Fellowship)
Neil & Anna Rasmussen Foundation
Grayce B. Kerr Fund, Inc. (Fellowship)
MIT Energy Initiative (Shell-MITEI Graduate Fellowship)
Shell International Exploration and Production B.V. (N. Braunsdorf and D. Smit of Shell PTI/EG grant)