Distribution, composition, and ecological risk of surface sedimental polychlorinated naphthalenes in the East China Sea

To reveal the pollution levels and estimate the ecological risks of polychlorinated naphthalenes (PCNs) in the East China Sea (ECS), seventy-five surface sediment samples were collected and analyzed by high-resolution mass spectrometry. PCN contents ranged from below detection limit to 261.71 ng/g dry weight (d.w.), with an integrally seaward decreasing trend. Mono-, tetra-, and hepta-CNs were the dominant homologs, and CN-2, CN-73, and CN-75 were the major individual components in most samples. CN-2 presented an obvious boundary with lower contents (16.48 ± 3.40 ng/g d.w.) in the center of the study area and higher contents (50.88 ± 10.39 ng/g d.w.) in the north and south of the boundary. The toxic equivalent (TEQ) contents ranged from 0 to 0.212 ng/g, and CN-2 and CN-73 were the predominant contributors to the TEQ.