Occurrence, Spatial Distribution, Sources and Risk Assessment of Per- and Polyfluoroalkyl Substances in Surface Sediments of the Yellow River Delta Wetland

Per- and polyfluoroalkyl substances (PFASs) are emerging persistent organic pollutants (POPs). In this study, 47 surface sediment samples were collected from the Yellow River Delta wetland (YRDW) to investigate the occurrence, spatial distribution, potential sources, and ecological risks of PFASs. Twenty-three out of 26 targeted PFASs were detected in surface sediment samples from the YRDW, with total & sum;23PFASs concentrations ranging from 0.23 to 16.30 ng g-1 dw and a median value of 2.27 ng g-1 dw. Perfluorooctanoic acid (PFOA), perfluorobutanoic acid (PFBA) and perfluorooctanesulfonic acid (PFOS) were the main contaminants. The detection frequency and concentration of perfluoroalkyl carboxylic acids (PFCAs) were higher than those of perfluoroalkanesulfonic acids (PFSAs), while those of long-chain PFASs were higher than those of short-chain PFASs. The emerging PFASs substitutes were dominated by 6:2 chlorinated polyfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA). The distribution of PFASs is significantly influenced by the total organic carbon content in the sediments. The concentration of PFASs seems to be related to human activities, with high concentration levels of PFASs near locations such as beaches and villages. By using a positive matrix factorization model, the potential sources of PFASs in the region were identified as metal plating mist inhibitor and fluoropolymer manufacturing sources, metal plating industry and firefighting foam and textile treatment sources, and food packaging material sources. The risk assessment indicated that PFASs in YRDW sediments do not pose a significant ecological risk to benthic organisms in the region overall, but PFOA and PFOS exert a low to moderate risk at individual stations.