Methane cycling. Nonequilibrium clumped isotope signals in microbial methane.
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 (for example, (13)CH3D) has recently emerged as a proxy for determining methane-formation temperatures. However, the effect 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 (13)CH3D 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.
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
David T
DT
Wang
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
Danielle S
DS
Gruen
Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada.
Barbara Sherwood
BS
Lollar
MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen D-28359, Germany.
Kai-Uwe
KU
Hinrichs
Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
Lucy C
LC
Stewart
Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
James F
JF
Holden
Department of Animal Science, Pennsylvania State University, University Park, PA 16802, USA.
Alexander N
AN
Hristov
U.S. Geological Survey (USGS), Woods Hole Coastal and Marine Science Center, Woods Hole, MA 02543, USA.
John W
JW
Pohlman
Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland and Labrador A1B 3X5, Canada.
Penny L
PL
Morrill
MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen D-28359, Germany.
Martin
M
Könneke
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Kyle B
KB
Delwiche
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Eoghan P
EP
Reeves
Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada.
Chelsea N
CN
Sutcliffe
Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA.
Daniel J
DJ
Ritter
Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
Jeffrey S
JS
Seewald
Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA.
Jennifer C
JC
McIntosh
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Harold F
HF
Hemond
NASA Ames Research Center, Moffett Field, CA 94035, USA.
Michael D
MD
Kubo
Department of Geosciences, University of Rhode Island, Kingston, RI 02881, USA.
Dawn
D
Cardace
NASA Ames Research Center, Moffett Field, CA 94035, USA.
Tori M
TM
Hoehler
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. sono@mit.edu.
Shuhei
S
Ono
D000818:Animals; D057486:Carbon Cycle; D002247:Carbon Isotopes / Q000737:chemistry; D002417:Cattle; D060587:Groundwater / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D008697:Methane / Q000096:biosynthesis* / Q000737:chemistry; D017018:Methanomicrobiales / Q000378:metabolism*; D013696:Temperature
D002247:Carbon Isotopes; D006859:Hydrogen; D008697:Methane