[Pollution Characteristics and Risk Assessment of Per- and Polyfluoroalkyl Substances in Surface Water and Sediments...

Per- and polyfluoroalkyl substances （PFASs） have recently attracted widespread attention as emerging contaminants. To investigate the pollution characteristics， spatiotemporal distribution patterns， and migration behavior of PFASs in surface water and sediments of Linshui River， surface water and sediment samples were collected during the wet and dry seasons. Fifteen PFASs were analyzed using ultra-high-performance liquid chromatography-tandem mass spectrometry. Combined with elemental analysis and organic carbon （OC） content measurements， multivariate statistical methods-including principal component analysis （PCA）， Spearman correlation analysis， positive matrix factorization （PMF）， and ecological risk assessment-were applied to ① reveal the competitive adsorption between PFASs and heavy metals （HMs） on clay minerals in sediments， ② identify the sources of PFASs， and ③ evaluate their ecological risks. The results indicated that PFASs concentrations in both water and sediments were higher during the dry season than in the wet season. The total concentrations of 15 PFASs in surface water during the dry season ranged from 22.66 to 143.54 ng·L^-1 （excluding H7）， which were lower than those reported in the Han River Basin and Yellow River Basin. Strong positive correlations among perfluorocarboxylic acids （PFCAs） and perfluorosulfonic acids （PFSAs） suggested similar pollution sources. The sediment-water partition coefficients （lgK_d） ranged from 0.95 to 2.74 and increased with carbon chain length， indicating that chain length plays a critical role in the environmental distribution of PFASs. Furthermore， sediments preferentially adsorbed metal cations， followed by PFASs， and the content of PFASs in sediments was significantly consistent with the organic carbon content （OC）. PMF model source analysis revealed that the pollution of PFASs in the surface water and sediments of Linshui River showed obvious point source pollution characteristics， mainly from industrial discharges （42%） and agricultural activities （42.2%）， with a relatively low contribution from domestic wastewater pollution （15.8%）. Ecological risk assessment indicated that the impact of PFASs in surface water on the ecological environment was low， and only a few sediment sites had potential perfluorooctane sulfonic acid （PFOS） risk.