Legacy and emerging per- and polyfluoroalkyl substances (PFAS) in the Bohai Sea and its inflow rivers

In this study, the occurrence, distribution, sources, and risk of 29 legacy and emerging per- and polyfluoroalkyl substances (PFAS) in four kinds of environmental matrices in the Bohai Sea were investigated. The ∑PFAS concentrations were in the range of 0.40 ~ 61.4 ng/g dry weight (dw) in inflow river sediments, 0.48 ~ 61.4 ng/g dw in soil near river inflow, 0.37 ~ 4.18 ng/g dw in sea sediments, and 13.3 ~ 718 ng/L in seawater. PFAS with eight carbons accounted for > 62.2% by mass, in all samples. Perfluorooctanoic acid (PFOA) was the dominant PFAS both by mass and occurrence. Seawater from Laizhou Bay (south of the Bohai Sea) and sediments of Liaodong Bay (northeast of the Bohai Sea) had the highest levels of ∑PFAS. The sediment-water partition coefficient and organic carbon content normalized partition coefficient (log K_d and log K_oc) were calculated using measured PFAS concentrations to determine their distribution in seawater and sea sediments. The values of log K_d and log K_oc values increased with the increasing CF₂ units for perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs). Six primary sources were identified in this region, including aqueous film-forming foams (AFFF), metal plating, food packages, fluorine chemical industry, fluoropolymer manufacture, and domestic pollution. The risk quotient (RQ) values of PFAS were all < 1, indicating that organisms of the Bohai Sea were at low risk of PFAS exposure.