CO2 uptake potential of the East Asian Marginal Seas: Yellow, East China, and East/Japan Seas

Several factors control the CO₂ fugacity (fCO₂) in the water column of the East Asian Marginal Seas (EAMS). This study investigates the distribution of fCO₂ in the EAMS using surveys data from the Yellow Sea, the East China Sea, and the East/Japan Sea (EJS). It provides the first comprehensive mapping and analysis of fCO₂ throughout the entire water column of the EAMS. The results indicate that, except for the Yellow Sea in summer, the EAMS is an annual sink of atmospheric CO₂, with uptake rates ranging from 0.4 to 2.1 mol C m⁻² yr⁻¹. Below the surface, the decomposition of organic matter (through the EAMS) and the dissolution of carbonate minerals (in the EJS) led to a substantial increase in fCO₂, effectively facilitating CO₂ uptake into the ocean interior. From the surface to the ocean interior, EJS exhibits the most substantial potential for CO₂ uptake. fCO₂ is sensitive to various physical and biogeochemical processes. Therefore, understanding complex marginal sea (coastal sea) environments such as the EAMS requires continuous and extensive observation.