Occurrence, spatial and temporal distribution, sources and ecological risk assessment of halogenated polycyclic aromatic hydrocarbons (HPAHs) in sediments of the East China Sea.

Halogenated polycyclic aromatic hydrocarbons (HPAHs) in marine environment have attracted increasing attention due to their persistence, bioaccumulation potential, and ecological toxicity. However, systematic investigations on their contamination levels, compositional distribution, and source apportionment in the surface sediments of the East China Sea (ECS) remain limited. In this study, 25 HPAHs were quantitatively analyzed in ECS surface sediments, revealing total concentrations ranging from 14.50 to 131.19 ng g dry weight (dw), with a mean value of 42.23 ± 29.60 ng g dw. Notably, brominated PAHs (Br-PAHs: 30.74 ± 24.46 ng g dw) exhibited significantly higher concentrations than chlorinated PAHs (Cl-PAHs: 11.49 ± 6.18 ng g dw). Among the 25 HPAHs, 9-ClFle and 9-BrFle were identified as the most abundant compounds. Total HPAH concentrations across stations correlated positively with water depth, salinity, and dissolved oxygen, but negatively with temperature and chlorophyll a. Spatial patterns showed pronounced heterogeneity, with higher mean values in the south (65.85 ng g dw) than in the north (32.66 ng g dw). This distribution likely reflects combined influences of industrial emissions, hydrodynamic transport, and atmospheric deposition. Positive matrix factorization identified five sources: brominated flame retardant production (27.2 %), petrochemical and electronic waste (21.6 %), metal smelting (6.8 %), transport-related inputs (16.1 %), and regional atmospheric deposition (28.3 %). Ecological risk assessment using bioavailability-adjusted risk quotients (RQ) indicated that brominated congeners posed higher potential risks than chlorinated ones, yet overall risks to aquatic organisms remained below the low-risk threshold. These findings underscore the anthropogenic-environmental interplay shaping HPAH distribution in ECS sediments and inform future management strategies.