PAES and PAHs in the surface sediments of the East China Sea: Occurrence, distribution and influence factors

[Display omitted] •Different distributions of PAEs and PAHs were observed in the surface sediment of the East China Sea.•Yangtze River input was a major contributor of PAEs in the surface sediments.•Both Yangtze River input and sedimentary geochemistry affected the distribution of PAHs in the surface sediments.•Organic carbon from different sources has different effects on the distribution of pollutants in sediments. A total of 29 sediment samples were collected from the East China Sea (ECS), with the Yangtze River estuary and the Zhejiang costal area. These sediment samples were analyzed for 6 phthalate esters (PAEs) and 16 polycyclic aromatic hydrocarbons (PAHs): the ΣPAEs and ΣPAHs concentrations ranged between 1649.5 and 8451.5 ng g−1 (mean = 3446.3 ng g−1) and 57.5–364.5 ng g−1 (mean = 166.2 ng g−1), respectively. Overall, the PAEs and PAHs concentrations gradually decreasing in the offshore and southward directions: their compositions and distributions suggest they could have mainly derived from the Yangtze River. In particular, their distribution was influenced by the sources’ proximity, hydrodynamics, and sediment geochemistry (i.e., TOC content and grain size). A classical two-end member model was utilized to estimate the fraction of terrestrial organic carbon in the sediments of the ECS. When the sediment was dominated by terrestrial-derived organic matter (OM), the concentrations of PAEs and PAHs were significantly correlated to the TOC content and gran size of the sediments. In contrast, the poor correlation of TOC content and grain size with PAEs in those sediments dominated by marine-derived OM, implied that the distribution of PAEs in the ECS was mainly related to land-based inputs, (especially to that of the Yangtze River). Regardless of the origin of most of the OM contained in the sediments, we observed positive correlations between the TOC content, and grain size of those containing PAHs. These results suggest that the distribution of PAHs in the ECS was not only related to the Yangtze River input, but also to the geochemical characteristics of the sediments.