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

Peter M.J. Douglas, Regina Gonzalez Moguel, Katey M. Walter Anthony, Martin Wik, Patrick M. Crill, Katherine S. Dawson, Derek A. Smith, Ella Yanay, Max K. Lloyd, Daniel A. Stolper, John M. Eiler, Alex L. Sessions

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

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.

Original languageEnglish (US)
Article numbere2019GL086756
JournalGeophysical Research Letters
Volume47
Issue number6
DOIs
StatePublished - Mar 28 2020

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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