INT-01 SOLAS: Air-Sea interaction
Dynamics and controls of methane oxidation in the aerobic waters of East China Sea and Yellow Sea
Qiao Liu* , 1. Frontiers Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China. 2. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
Xiaojun Li, 1. Frontiers Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China. 2. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
Ni Meng, 1. Frontiers Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China. 2. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
Guiling Zhang, 1. Frontiers Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China. 2. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
Gui-Peng Yang, 1. Frontiers Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China. 2. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China
Guang-Chao Zhuang, 1. Frontiers Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China. 2. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China

Methane is supersaturated in surface seawater and shallow coastal waters dominate global ocean methane emissions to the atmosphere. Aerobic methane oxidation (MOx) is a crucial mechanism in controlling methane emissions, while the dynamics and controls of MOx are not fully understood. In this study, we conducted a variety of biogeochemical analyses to investigate the controls of methane cycling and the dynamics of methanotrophic activity in East China Sea and Yellow Sea. Methane concentrations in the surface seawater ranged from 2.8 to 19.8 nmol·L-1, and the distribution was influenced by environmental factors such as hydrological conditions, chlorophyll and nutrients levels. Methane was rapidly metabolized and high MOx rates observed in these areas were correlated with methanotrophic activity and biomass. Molecular analysis revealed Methylophilales dominated methanotrophic communities at nearshore sites. Air-sea fluxes indicated that up to 0.0248 Tg methane was released annually to the atmosphere from the ECS. However, depth-integrated MOx was higher than methane sea-air fluxes at offshore sites, which accounted for up to 78.4 % of the total methane loss, suggest that MOx acted as a key methane sink that significantly reduced methane emissions.