Perfluoroalkyl acids in surface sediments from the lower Yangtze River: Occurrence, distribution, sources, inventory, and risk assessment.

In this study, the occurrence, spatial distribution, potential sources, mass inventory, and ecological risk assessment of perfluoroalkyl acids (PFAAs) in surface sediments from the lower Yangtze River were investigated based on field and laboratory assays conducted in November 2019. The total concentrations of 13 target PFAAs (∑PFAAs) ranged from 13.83 to 20.33 ng/g dw, and perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) were predominant in the surface sediments with average concentrations of 2.89 and 4.07 ng/g dw, respectively. The ∑PFAAs concentrations in pore-water ranged from 23.30 to 58.81 ng/L, and PFOA and PFOS were predominant with mean concentrations of 6.29 and 5.04 ng/L, respectively. The profiles of PFAAs composition in surface sediments showed limited difference. Results of fugacity model revealed that PFOS was in relative equilibrium, whereas PFOA exhibited a diffusion trend from sediments to water body. Correlation analysis and positive matrix factorization demonstrated that the main sources of ∑PFAAs were electroplating and fast-food packaging, degradation products and textile, mixed sources, and PFOA-based products. The mass inventory of ∑PFAAs was estimated to be 1680.72 kg, and the results of ecological risk assessments based on equilibrium partition and species sensitivity distribution methods suggested that the hazards of PFAAs in sediments to local aquatic organisms are low. However, the evaluation methods and control measures of PFAAs in surface sediments are still limited, requiring further research.