Microbial Methane From Methylphosphonate Isotopically Records Source

L. Taenzer, P. C. Carini, A. M. Masterson, B. Bourque, J. H. Gaube, W. D. Leavitt

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Methane is a potent greenhouse gas commonly supersaturated in the oxic surfaces waters of oceans and lakes, yet canonical microbial methanogens are obligate anaerobes. One proposed methane production pathway involves microbial degradation of methylphosphonate (MPn), which can proceed in the presence of oxygen. Directly tracing dissolved methane to its source in oxic waters, however, remains a challenge. To address this knowledge gap, we quantified the carbon isotopic fractionation between substrate MPn and product methane (1.3‰) in lab experiments, which was 1 to 2 orders of magnitude smaller than canonical pathways of microbial methanogenesis (20 to 100‰). Together, these results indicated that microbial catabolism of MPn is a source of methane in surface oceans and lake waters, but to differentiate sources of MPn in nature a further accounting of all sources is necessary. Methane from this pathway must be considered in constraining the marine carbon cycle and methane budget.

Original languageEnglish (US)
Article numbere2019GL085872
JournalGeophysical Research Letters
Volume47
Issue number1
DOIs
StatePublished - Jan 16 2020
Externally publishedYes

Keywords

  • C-P lyase
  • carbon isotopes
  • marine methane paradox
  • methylphosphonate
  • surface ocean

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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