Perfluoroalkyl acids (PFAAs) and their precursors in sediments and adjacent riparian soils from the Three Gorges Reservoir, China: Contamination characteristics, source apportionment and ecological risks

Abstract

Information on the occurrence and spatial distribution of perfluoroalkyl acids (PFAAs) and their precursors in sediments and adjacent riparian soils of Three Gorges Reservoir (TGR), which is one of the largest reservoirs in the world, is still limited. In this study, The total concentrations of these per- and polyfluoroalkyl substances (PFASs) ranged from 2220 to 19,300 pg/g in sediments and 298-9540 pg/g in soils. PFOA was the dominant PFAS in sediments and soils, accounting for 23.4% and 30.7% of the total median cocentrations of PFASs, respectively. PFAA precursors, such as 4:2 fluorotelomer sulfonate (4:2 FTS), 6:2 fluorotelomer sulfonate (6:2 FTS), and perfluorooctane sulfonamide (FOSA), were widely detected in sediments and soils. The distribution of PFASs exhibited distinct spatial variations and was more influenced by anthropogenic activities. Positive matrix factorization (PMF) identified fire-fighting foams (AFFF) and legacy fluoropolymer industry/textile treatment were the dominant sources in sediments (31.5%) and soils (30.8%), respectively. Finally, the ecological risk assessment showed that PFOS exhibited low to medium risks. Our findings indicate that the contamination of PFAA precursors must be considered when developing management measures to protect the TGR region.