Methoxyl stable isotopic constraints on the origins and limits of coal-bed methane
Abstract
Microbial coal-bed methane is an important economic resource and source of a potent greenhouse gas, but controls on its formation are poorly understood. To test whether the microbial degradability of coal limits microbial methane, we monitored methoxyl group demethylation—a reaction that feeds methanogenesis—in a global sample suite ranging in maturity from wood to bituminous coal. Carbon isotopic compositions of residual methoxyl groups were inconsistent with a thermal reaction, instead implying a substrate-limited biologic process. This suggests that deep biosphere communities participated in transforming plant matter to coal on geologic time scales and that methoxyl abundance influences coal-bed methane yield. Carbon isotopic enrichments resulting from microbial methylotrophy also explain an enigmatic offset in the carbon-13 content of microbial methane from coals and conventional hydrocarbon deposits.
Additional Information
© 2021 American Association for the Advancement of Science. Received 8 December 2020; accepted 13 September 2021. We thank K. Snell for use of analytical facilities and M. Formolo and S. Petsch for sharing materials. Shimokita samples were provided by the International Ocean Discovery program. H. L. O. McClelland, D. Stolper, A. Schimmelmann, C. Ponton, and H. Lee provided helpful suggestions at various stages of the project. This work was supported by NSF EAR 1322058 to J.M.E.; a NASA postdoctoral fellowship with the NASA Astrobiology Institute to E.T.-R.; the L'Oréal USA For Women in Science fellowship to E.T.-R.; the L'Oréal-UNESCO FWIS International Rising Talent Endowment to E.T.-R.; and the ACS award PRF-53747-ND2 to S.J.F., which initiated their work on this project. Author contributions: Conceptualization: M.K.L. and E.T.-R.; Methodology: M.K.L., E.T.-R., S.J.F., A.L.S., and J.M.E.; Investigation: M.K.L., E.T.-R., and K.S.D.; Resources: E.T.-R., S.J.F., M.M., V.J.O., A.L.S., and J.M.E.; Writing – original draft: M.K.L.; Writing – review and editing: M.K.L., E.T.-R., S.J.F., M.M., V.J.O., A.L.S., and J.M.E.; Supervision and funding acquisition: J.M.E. The authors have no competing interests on this project. Data and materials availability: All data are available in the main text or the supplementary materials.Attached Files
Supplemental Material - science.abg0241_mdar_reproducibility_checklist.pdf
Supplemental Material - science.abg0241_sm.pdf
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Additional details
- Eprint ID
- 111848
- DOI
- 10.1126/science.abg0241
- Resolver ID
- CaltechAUTHORS:20211111-215750456
- NSF
- EAR-1322058
- NASA Postdoctoral Program
- L'Oreal USA For Women in Science Fellowship
- L'Oréal-UNESCO FWIS International Rising Talent Endowment
- American Chemical Society Petroleum Research Fund
- PRF-53747-ND2
- Created
-
2021-11-11Created from EPrint's datestamp field
- Updated
-
2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences, Division of Biology and Biological Engineering