Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) in the Yangtze River: Distribution, Transport, and Influencing Factors

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in global river basins. Although the localized influence of the Three Gorges Dam (TGD) on PFAS remobilization is known, a comprehensive investigation of both water and sediment along the entire Yangtze River is lacking. In 2023, 32 PFAS were quantified in water and sediment along over 4000 km of the Yangtze River (China’s longest river) and some of its tributaries and nearby lakes. The ∑PFAS concentrations ranged from 5.5 to 340 ng/L in water and 0.13 to 28 ng/g dry weight (dw) in sediments. Higher concentrations were found in water in the preflood period than the postflood period. Notably, short-chain replacement compounds, especially perfluorobutanoic acid (PFBA) and perfluorobutanesulfonate acid (PFBS), dominated the PFAS profile, indicating a compositional shift following legacy homologue restrictions. Spatial analysis revealed elevated concentrations (>100 ng/L) proximate to industrial parks, identifying them as probable point sources. TGD operation created unique hydrological conditions within the Three Gorges Reservoir, resulting in very low PFAS levels (<0.01 ng/g) on suspended particulate matter. Flux calculations indicated that PFAS transportation via the dissolved phase dominated over the particulate phase. Nontarget and suspect screening analysis revealed the occurrence of ultrashort-chain PFAS (C ≤ 3) in water.