The optimum multiparameter (OMP) method was often used to determine the percentages of water masses based on temperature, salinity and other parameters, like nutrient or dissolved oxygen (DO). There are a number of water masses in the East China Sea (ECS), a marginal sea of the western Pacific Ocean. However, it is difficult to clarify the proportion of water masses using traditional parameters, such as temperature, salinity, nutrient or DO because of the occurring of intensive biogeochemical processes in the near shore and shelf areas. Here, we reported the use of ²³⁴U/²³⁸U activity ratio embedded in the OMP method. The results indicate that seawater in the northern ECS mainly consisted of the estuarine water of Changjiang River (CEW), Kuroshio water (KW), and Yellow Sea Coastal Current (YSCC). In March 2017, the CEW only influenced the offshore waters shallower than 30 m; the KW affected the east edge and the YSCC contributed more than 75% in the northern ECS.

最佳多参数 (OMP) 方法通常用于根据温度、盐度和其他参数（如养分或溶解氧 (DO)）确定水团的百分比。东海（ECS）是西太平洋的边缘海，存在大量水团。然而，由于近岸和陆架区域发生了密集的生物地球化学过程，因此难以使用传统参数（如温度、盐度、营养物或溶解氧）来阐明水团的比例。在这里，我们报告了使用²³⁴ U/ ²³⁸OMP 方法中嵌入的 U 活度比。结果表明，ECS北部海水主要由长江口水（CEW）、黑潮水（KW）和黄海沿岸流（YSCC）组成。2017 年 3 月，CEW 仅影响浅于 30 m 的近海水域；KW 影响了东部边缘，YSCC 在 ECS 北部贡献了 75% 以上。