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Environ Pollut. 2019 Jan;244:228-237. doi: 10.1016/j.envpol.2018.10.057. Epub 2018 Oct 14.

Regulation of coastal methane sinks by a structured gradient of microbial methane oxidizers.

Author information

1
Department of Environmental Engineering, Zhejiang University, Hangzhou, China; College of Environment, Zhejiang University of Technology, Hangzhou, China.
2
Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
3
Department of Chemistry, University of Science & Technology of China, Hefei, China.
4
Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Nijmegen, the Netherlands.
5
Department of Environmental Engineering, Zhejiang University, Hangzhou, China; Key Laboratory of Water Pollution Control and Environmental Safety of Zhejiang Province, Hangzhou, China. Electronic address: blhu@zju.edu.cn.

Abstract

Coastal wetlands are widely recognized as atmospheric methane sources. However, recent field studies suggest that some coastal wetlands could also act as methane sinks, but the mechanism is not yet clear. Here, we investigated methane oxidation with different electron acceptors (i.e., oxygen, nitrate/nitrite, sulfate, Fe(III) and Mn(IV)) in four coastal wetlands in China using a combination of molecular biology methods and isotopic tracing technologies. The geochemical profiles and in situ Gibbs free energies suggest that there was significant nitrite-dependent anaerobic oxidation of methane (nitrite-AOM) in the sub-surface sediments; this was subsequently experimentally verified by both the microbial abundance and activity. Remarkably, the methanotrophic communities seemed to exist in the sediments as layered structures, and the surface aerobic methane-oxidizing bacteria were able to take up atmospheric methane at a rate of 0.10-0.18 nmol CH4 day-1 cm-2, while most, if not all, sedimentary methane was being completely consumed by anaerobic methanotrophs (23-58% by methane oxidizers in phylum NC10). These results suggest that coastal methane sinks might be governed by diverse microbial communities where NC10 methane oxidizers contributed significantly. This finding helps to better understand and predict the coastal methane cycle and reduce uncertainties in the estimations of the global methane flux.

KEYWORDS:

Coastal ecosystem; Ecological niche; Methane cycle; Methanotrophic community; Nitrite-dependent anaerobic oxidation of methane (nitrite-AOM)

PMID:
30342364
DOI:
10.1016/j.envpol.2018.10.057
[Indexed for MEDLINE]

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