Occurrence and distribution of brominated and fluorinated persistent organic pollutants in surface sediments focusing on industrially affected rivers

This study investigated legacy persistent organic pollutants, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), and per- and polyfluoroalkyl substances (PFAS), as well as their alternatives, in sediments from five major rivers, to assess their contamination status and usage patterns. The concentration levels of ΣPBDEs (median 9.98 ng/g dry weight (dw), mean 190 ng/g dw), ΣHBCDs (median 9.35 ng/g dw, mean 39.8 ng/g dw), Σnovel brominated flame retardants (NBFRs) (median not detected, mean 821 ng/g dw), and ∑PFAS (median 1.14 ng/g dw, mean 13.9 ng/g dw) in river sediments affected by high industrial activity were statistically significantly higher than at other sites with less or no industrial activity (Kruskal-Wallis test, p < 0.05). The dominant compounds among legacy substances for brominated flame retardants (BFRs) and PFAS are decaBDE for PBDEs, γ-HBCD for HBCDs, and perfluorooctane sulfonate (PFOS) for PFAS. The detection frequencies of 1,2-Bis(2,4,6-tribromophenoxy)ethane (BTBPE) and 6:2 chlorinated perfluoroalkylether sulfonic acid (F53B), as alternative substances for PBDEs and PFOS, were 16% and 9%, respectively. Regarding substances used as alternatives for perfluorooctanoic acid (PFOA) were detected at only one site for hexafluoropropylene oxide dimer acid (Gen-X), while 4,8-dioxo-3H-perfluorononanoic acid (ADONA) was not detected. The hazard quotient (HQ) values from the ecological risk assessment were generally low (HQ < 1), except for ΣPBDEs and PFOS at several sites. The present study emphasizes the need for continuous monitoring and risk assessment of these pollutants in river sediments, particularly in industrial areas, and highlights the importance of addressing the ecological toxicity of these substances to safeguard aquatic ecosystems.