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Clumped Isotopes Link Older Carbon Substrates With Slower Rates of Methanogenesis in Northern Lakes

Douglas, Peter M. J. and Moguel, Regina Gonzalez and Anthony, Katey M. Walter and Wik, Martin and Crill, Patrick M. and Dawson, Katherine S. and Smith, Derek A. and Yanay, Ella and Lloyd, Max K. and Stolper, Daniel A. and Eiler, John M. and Sessions, Alex L. (2020) Clumped Isotopes Link Older Carbon Substrates With Slower Rates of Methanogenesis in Northern Lakes. Geophysical Research Letters, 47 (6). Art. No. e2019GL086756. ISSN 0094-8276. https://resolver.caltech.edu/CaltechAUTHORS:20200408-093725679

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Abstract

The release of long‐stored carbon from thawed permafrost could fuel increased methanogenesis in northern lakes, but it remains unclear whether old carbon substrates released from permafrost are metabolized as rapidly by methanogenic microbial communities as recently produced organic carbon. Here, we apply methane (CH₄) clumped isotope (Δ₁₈) and ¹⁴C measurements to test whether rates of methanogenesis are related to carbon substrate age. Results from culture experiments indicate that Δ₁₈ values are negatively correlated with CH₄ production rate. Measurements of ebullition samples from thermokarst lakes in Alaska and glacial lakes in Sweden indicate strong negative correlations between CH₄ Δ₁₈ and the fraction modern carbon. These correlations imply that CH₄ derived from older carbon substrates is produced relatively slowly. Relative rates of methanogenesis, as inferred from Δ₁₈ values, are not positively correlated with CH₄ flux estimates, highlighting the likely importance of environmental variables other than CH₄ production rates in controlling ebullition fluxes.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2019gl086756DOIArticle
https://doi.org/10.6084/m9.figshare.11831340.v1DOIData
ORCID:
AuthorORCID
Douglas, Peter M. J.0000-0002-4282-6615
Wik, Martin0000-0003-0368-4623
Crill, Patrick M.0000-0003-1110-3059
Dawson, Katherine S.0000-0001-8856-4609
Lloyd, Max K.0000-0001-9367-2698
Stolper, Daniel A.0000-0003-3299-3177
Sessions, Alex L.0000-0001-6120-2763
Additional Information:© 2020 American Geophysical Union. Received 19 DEC 2019; Accepted 5 MAR 2020; Accepted article online 09 MAR 2020. We thank Nami Kitchen for help with Δ₁₈ analyses, Sarah Murseli for help with ¹⁴C analyses, and Nathan Dalleska for help with CH₄ concentration measurements. Victoria Orphan and Jared Leadbetter provided laboratory facilities for culture experiments. This research was partially supported by funds from the Trottier Institute for Science and Public Policy to PMJD, from Royal Dutch Shell to JME and ALS, from the Agouron Institute to MKL, from the Heising‐Simons Foundation to DA Stolper, and from Vetenskapsrådet 2013‐5562 to PC. Data supporting this article are available at https://doi.org/10.6084/m9.figshare.11831340.v1.
Funders:
Funding AgencyGrant Number
Trottier Institute for Science and Public PolicyUNSPECIFIED
Royal Dutch ShellUNSPECIFIED
Agouron InstituteUNSPECIFIED
Heising‐Simons FoundationUNSPECIFIED
Vetenskapsrådet2013‐5562
Subject Keywords:methane; permafrost; clumped isotopes; radiocarbon; ebullition flux; lakes
Issue or Number:6
Record Number:CaltechAUTHORS:20200408-093725679
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200408-093725679
Official Citation:Douglas, P. M. J., Gonzalez Moguel, R., Walter Anthony, K. M., Wik, M., Crill, P. M., Dawson, K. S., et al. (2020). Clumped isotopes link older carbon substrates with slower rates of methanogenesis in northern lakes. Geophysical Research Letters, 47, e2019GL086756. https://doi.org/10.1029/2019GL086756
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102400
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:08 Apr 2020 16:48
Last Modified:05 Oct 2020 16:16

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