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Aerobic oxidation of methane significantly reduces global diffusive methane emissions from shallow marine waters.

Shi-Hai MaoHong-Hai ZhangGuang-Chao ZhuangXiao-Jun LiQiao LiuZhen ZhouWei-Lei WangChun-Yang LiKe-Yu LuXi-Ting LiuAndrew MontgomerySamantha B JoyeYu-Zhong ZhangGui-Peng Yang
Published in: Nature communications (2022)
Methane is supersaturated in surface seawater and shallow coastal waters dominate global ocean methane emissions to the atmosphere. Aerobic methane oxidation (MOx) can reduce atmospheric evasion, but the magnitude and control of MOx remain poorly understood. Here we investigate methane sources and fates in the East China Sea and map global MOx rates in shallow waters by training machine-learning models. We show methane is produced during methylphosphonate decomposition under phosphate-limiting conditions and sedimentary release is also source of methane. High MOx rates observed in these productive coastal waters are correlated with methanotrophic activity and biomass. By merging the measured MOx rates with methane concentrations and other variables from a global database, we predict MOx rates and estimate that half of methane, amounting to 1.8 ± 2.7 Tg, is consumed annually in near-shore waters (<50 m), suggesting that aerobic methanotrophy is an important sink that significantly constrains global methane emissions.
Keyphrases
  • anaerobic digestion
  • carbon dioxide
  • municipal solid waste
  • machine learning
  • sewage sludge
  • climate change
  • risk assessment
  • nitric oxide
  • particulate matter
  • liquid chromatography