Insights into the occurrence and environmental behavior of legacy and emerging PFAS in the Three Gorges Reservoir region: Tributary deserves further attention

Transport of per- and polyfluoroalkyl substances (PFAS) to the Yangtze River is a growing concern because the river provides drinking water for over 400 million people. However, tributary PFAS inputs to the Yangtze River remain poorly characterized, and the potential risks in numerous tributaries are largely unknown. In this study, 29 legacy and emerging PFAS were quantified in water (13.3–316 ng/L), suspended particulate matter (SPM) (0.67–40.2 ng/L), and sediment (0.52–387 ng/g) collected from the Three Gorges Reservoir (TGR) region of the Yangtze River and its tributaries. Perfluorobutyric acid (PFBA) was the most abundant individual PFAS in water, whereas perfluorooctanoic acid (PFOA) and 6:2 fluorotelomer sulfonic acid (6:2 FTS) were the predominant compounds in SPM and sediment, respectively. Our analysis reveals that PFAS discharge from tributaries is a dominant contributor to PFAS accumulation in receiving waters. While larger tributaries in the TGR region generally exhibit lower aqueous PFAS concentrations than smaller tributaries, they account for the majority of the total PFAS flux entering the Yangtze River. Our results demonstrate that PFAS alternatives, including PFBA, perfluorohexanoic acid (PFHxA) and 6:2 FTS, are growing in relative prominence as replacement compounds for legacy PFAS. PFBA and PFOA were found to pose potential ecological and human health risks in tributary water, highlighting the need for future regulatory measures concerning these PFAS compounds in the tributaries of the TGR region.