Evidence for the anaerobic oxidation of methane coupled to nitrous oxide reduction in landfill cover soils: Promotor and inhibitor

Abstract

Anaerobic oxidation of methane coupled to nitrous oxide reduction (N₂O-AOM) is an important microbial pathway for mitigating greenhouse gases. However, it remains largely unknown whether this process could occur in landfills, which are important anthropogenic sources of greenhouse gases emissions. Here, ¹³CH₄ was supplied in microcosm incubations to track potential rates for the N₂O-AOM process in landfill cover soils (LCS). The highest rates for the N₂O-AOM process were observed in the bottom layers of LCS and it could be remarkably promoted by the addition of electron shuttles. In addition, 2-bromoethanesulfonic sodium inhibited the N₂O-AOM process and reduced the expression of the mcrA gene, showing that ANME archaea/methanogens might be the methane oxidizers for the N₂O-AOM process. Our results implied that the N₂O-AOM process was an overlooked process for synchronous control of methane and nitrous oxide and may contribute to the future management of greenhouse gases emissions from landfills.

Keywords: Anaerobic methane oxidation; Electron shuttle; Landfill cover soil; Nitrous oxide.