Iron oxides impact sulfate-driven anaerobic oxidation of methane in diffusion-dominated marine sediments

Omer Yorshansky, Lewen Liang, André Pellerin, Fengping Wang, Barak Herut, Orit Sivan

Research output: Contribution to journalArticlepeer-review

Abstract

Microbial iron (Fe) reduction by naturally abundant iron minerals has been observed in many anoxic aquatic sediments in the sulfidic and methanic zones, deeper than it is expected based on its energetic yield. However, the potential consequence of this “deep” iron reduction on microbial elemental cycles is still unclear in sediments where diffusion is the dominant transport process. In this contribution, we experimentally quantify the impact of iron oxides on sulfate-driven anaerobic oxidation of methane (S-AOM) within the sulfate methane transition zone (SMTZ) of marine diffusive controlled sediments. Sediments were collected from the oligotrophic Southeastern (SE) Mediterranean continental shelf and were incubated with 13C-labeled methane. We followed the conversion of 13C-labeled methane as a proxy of S-AOM and monitored the sediment response to hematite addition. Our study shows microbial hematite reduction as a significant process in the SMTZ, which appears to be co-occurring with S-AOM. Based on combined evidence from sulfur and carbon isotopes and functional gene analysis, the reduction of hematite seems to slow down S-AOM. This contrasts with methane seep environments, where iron oxides appear to stimulate S-AOM and hence attenuate the release of the greenhouse gas methane from the sediments. In the deep methanic zone, the addition of iron oxides inhibits the methanogenesis process and hence methane gas production. The inhibition effect deeper in the sediment is not related to Fe-AOM as a competing process on the methane substrate, since Fe-AOM was not observed throughout the methanic sediments with several iron oxides additions.

Original languageEnglish
Article number903918
JournalFrontiers in Marine Science
Volume9
DOIs
StatePublished - 15 Sep 2022
Externally publishedYes

Bibliographical note

Funding Information:
This project was supported by the NSFC grant (41921006, 42141003) to FW, and the ISF grant (2561/16) and the H2020 European Research Council grant (818450) to OS.

Publisher Copyright:
Copyright © 2022 Yorshansky, Liang, Pellerin, Wang, Herut and Sivan.

Keywords

  • AOM
  • iron
  • S isotopes
  • sediments
  • sulfate

ASJC Scopus subject areas

  • Oceanography
  • Global and Planetary Change
  • Aquatic Science
  • Water Science and Technology
  • Environmental Science (miscellaneous)
  • Ocean Engineering

Fingerprint

Dive into the research topics of 'Iron oxides impact sulfate-driven anaerobic oxidation of methane in diffusion-dominated marine sediments'. Together they form a unique fingerprint.

Cite this