Spatiotemporal variations and bioaccumulation of per- and polyfluoroalkyl substances and oxidative conversion of precursors in shallow lake water.

Per- and polyfluoroalkyl substances (PFAS) in water and fish from Nansi Lake, Chian and in inflowing tributaries and nearby sewage treatment plants (STPs) were determined to evaluate their distribution and bioaccumulation. The potential precursors of perfluoroalkyl acid (PFAA) present in the water were converted via hydroxyl radical oxidation. Over 3 seasons, the average concentration ranges of the 15 PFAA (∑PFAA) concentrations in Nansi Lake, inflowing tributaries, and STPs were 22.8-70.3, 19.5-43.5, and 84.1-129 ng L, respectively. Perfluorooctanoic acid, perfluorooctane sulfonate (PFOS), and short-chain PFAA (perfluorocarboxlate acid <8, perfluorosulfonate acids <6) were present in high concentrations in the lake and tributaries. PFAA concentration was the lowest during the wet season and the highest during the dry season. Moreover, PFAA precursors were converted to perfluorocarboxlate acid. The concentration of C8-based precursors was higher than that of the C6-based precursors in the lake and tributaries. The concentration of PFAA in the fish liver was higher than that in fish muscles, and PFOS was the dominant chemical present in fish. Potential risk assessment based on Environment Quality Standard revealed heavy PFOS contamination in the fish. Thus, the water of Nansi Lake was heavily polluted by PFAS.