Abstract
Phosphorus is an essential nutrient for the growth of marine life. Especially in the East China Sea (ECS) where phosphorus is limited compared to the rest of China's sea, the external input of phosphorus can cause changes in primary productivity, and even induce in harmful algal blooms. In May 2020, the National Natural Science Foundation of China carried out a scientific investigation in the shared Spring Voyage in the ECS. We choose the area between 120.93 ˚ E-125.9 ˚ E and 26.08˚ N - 32.35 ˚ N as research sites for the analysis of the main sources of phosphate in the ECS during summer. The samples were all from the voyage of the research ship (Xiangyanghong 18). Dissolved inorganic phosphorus in seawater was enriched, and dissolved inorganic phosphorus was extracted. Then we measured the oxygen isotopes of phosphate in seawater and introduced the two-component mixing model for the analysis of potential sources of phosphate. In order to further quantitatively analyze the contribution rate of phosphate from different sources in the ECS, we choose a Bayesian isotope mixing model. These data can be used to analyze the contribution of phosphate from different sources in seawater and are helpful to explore the influencing factors of phosphate in the ECS.