Occurrence of Halogenated Organic Contaminants in Surface Sediments of the Yangtze River Estuary and its Adjacent Marine Area

Halogenated organic contaminants such as chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) are one of the most important pollutants in the environment. In this study, the concentrations of halogenated organic contaminants including 7 Cl-PAHs and 18 Br-PAHs in the surface sediments collected from the Yangtze River Estuary and its adjacent marine area were analyzed for the first time. The total concentrations of 7 Cl-PAHs and 18 Br-PAHs in the sediment samples ranged from 4.50 to 18.38 ng·g-1 (average, 7.19 ng·g-1) and from 4.80 to 61.18 ng·g-1 (average, 14.11 ng·g-1), respectively, with the most detection of 9-chlorofluorene (17.79%) and 9-bromofluorene (58.49%). Our findings demonstrate significant regional variations in the contamination of Cl/Br-PAHs in the study area, with high concentration in Yangtze River Estuary. Source analysis of Cl/Br-PAHs by principal component analysis and positive matrix factorization model showed that Cl/Br-PAHs in the Yangtze River Estuary and its adjacent marine area primarily originated from industrial emissions (34.2%) and e-waste dismantling (33.6%). The potential toxicity of Cl/Br-PAHs was assessed using the toxicity equivalent quotient (TEQs), with the average levels of TEQCl-PAHs and TEQBr-PAHs in the surface sediments of 0.81 pg TEQ/g and 0.91 pg TEQ/g, respectively, suggesting that the potential ecological risks they pose should not be overlooked.