Carbon dioxide and related parameters in the East China Sea

A low-temperature, low-salinity water mass lying on the bottom of the shelf area in the northern area of the East China Sea (ECS) in summertime is regarded as remnant winter water. Carbonate and related parameters suggest that it may originate from the Yellow Sea Cold Water which is formed farther north. There are no apparent annual variations in the carbonate parameters in the Kuroshio east of the shelf break. The partial pressure of CO2 calculated from the pH, TA or TCO2 data in this study show that the surface water in the shelf area is undersaturated with CO2 in spring and summer. When combined with other data collected in different seasons, the results show that the shelf area of the ECS is indeed a net sink for atmospheric CO2. The shelf area of the ECS may absorb as much as 0.013–0.030 Gt C per year. The carbonate data also suggest that the Tsushima Warm Current is a branch of the Kuroshio.