Isotopic evidence of acetate turnover in Precambrian continental fracture fluids
The deep continental crust represents a vast potential habitat for microbial life where its activity remains poorly constrained. Organic acids like acetate are common in these ecosystems, but their role in the subsurface carbon cycle - including the mechanism and rate of their turnover - is still unclear. Here, we develop an isotope-exchange 'clock' based on the abiotic equilibration of H-isotopes between acetate and water, which can be used to define the maximum in situ acetate residence time. We apply this technique to the fracture fluids in Birchtree and Kidd Creek mines within the Canadian Precambrian crust. At both sites, we find that acetate residence times are <1 million years and calculated a rate of turnover that could theoretically support microbial life. However, radiolytic water-rock reactions could also contribute to acetate production and degradation, a process that would have global relevance for the deep biosphere. More broadly, our study demonstrates the utility of isotope-exchange clocks in determining residence times of biomolecules with possible applications to other environments.
Authors
- Alex L. Sessions (ORCID: https://orcid.org/0000-0001-6120-2763)
- Elliott P. Mueller (ORCID: https://orcid.org/0000-0002-6837-0409)
- Kai‐Uwe Hinrichs (ORCID: https://orcid.org/0000-0002-0739-9291)
- Verena B. Heuer (ORCID: https://orcid.org/0000-0002-1856-116X)
- John M. Eiler (ORCID: https://orcid.org/0000-0001-5768-7593)
- Oliver Warr (ORCID: https://orcid.org/0000-0001-8240-7979)
- Wolfgang Bach (ORCID: https://orcid.org/0000-0002-3099-7142)
- Jason D. Boettger (ORCID: https://orcid.org/0000-0002-2853-8772)
- Alexander Meshoulam (ORCID: https://orcid.org/0009-0006-0566-0157)
- Barbara Sherwood Lollar (ORCID: https://orcid.org/0000-0001-9758-7095)
- Victoria J. Orphan (ORCID: https://orcid.org/0000-0002-5374-6178)
- Christian T. Hansen (ORCID: https://orcid.org/0000-0003-4943-0231)
- Juliann Panehal
- Min Song (ORCID: https://orcid.org/0000-0002-3291-0282)
Institutions
- California Institute of Technology (US)
- Institut de physique du globe de Paris (FR)
- University of Ottawa (CA)
- The University of Texas at El Paso (US)
- University of Bremen (DE)
- University of Toronto (CA)
- Université Paris Cité (FR)
Publication Details
- Journal
- Nature Communications
- Published
- 2024-10-23
- DOI
- https://doi.org/10.1038/s41467-024-53438-4
- Citations
- 7
- Primary Topic
- Methane Hydrates and Related Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 1.75
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- California Institute of Technology
- Canadian Institute for Advanced Research
- Deutsche Forschungsgemeinschaft
- Nuclear Safety and Security Commission
- NASA Astrobiology Institute