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

Anaerobic oxidation of methane coupled to nitrous oxide reduction (N 2 O-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, 13 CH 4 was supplied in microcosm incubations to track potential rates for the N 2 O-AOM process in landfill cover soils (LCS). The highest rates for the N 2 O-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 N 2 O-AOM process and reduced the expression of the mcr A gene, showing that ANME archaea/methanogens might be the methane oxidizers for the N 2 O-AOM process. Our results implied that the N 2 O-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.