Contamination profile of per- and polyfluoroalkyl substances and their potential precursors in the aquatic environment of important bathing beaches in China.

Per-and polyfluoroalkyl substances (PFAS) are globally distributed chemicals. Bathing seawater has high requirements for water quality. In this study, a national-scale investigation on the levels, the spatiotemporal distribution trends, and the bioconcentrations of PFAS in the water from some important bathing beaches in China were conducted for the first time. The total concentrations of ΣPFAS ranged from 8.24 to 140.97 ng/L. After oxidative conversion, ΣPFAS levels increased by 6.20% to 66.38%, confirming the significant presence of precursors. Potential PFAS precursors in the water of beaches were studied by an oxidative conversion method. The results showed that most perfluoroalkyl acids (PFAAs) were detectable in water of bathing beaches. The highest PFAA concentrations were found in December. Short-chain perfluorocarboxylic acid (PFCA) comprised more than 60% of ΣPFAS. Perfluorobutanoate acid (PFBA) and perfluorooctanoic acid (PFOA) were prevalent for all water samples. The PFAS concentrations exhibited obvious spatiotemporal variations. Tourism activities may have a potential but limited influence on localized PFAS levels. Oxidative treatment can effectively transform potential precursors into short-chain PFAAs. The results verified the PFAA precursors' existence in the water of beaches. PFAA precursors increased the levels in water. Therefore, some effective environmental management measures should be adopted for safeguarding water quality of bathing beaches.