Legacy and emerging per- and polyfluoroalkyl substances (PFASs) in multi-media around a landfill in China: Implications for the usage of PFASs alternatives

To date, per- and polyfluoroalkyl substances (PFASs) in environmental media surrounding landfills have not attracted much attention. In this study, six legacy PFASs, six short-chain analogues and five emerging alternatives were investigated in groundwater, surface water and sediment samples taken in the vicinity of a valley-type landfill, which had been in operation for over 20 years. Total PFAS concentrations of 110-236 ng/L, 17.3-163 ng/L and 7.91-164 ng/g dw were detected in the surface water, groundwater and sediment samples, respectively. Overall, perfluorooctanoic acid (PFOA) was the dominant PFAS in surface water, but elevated concentrations of perfluorobutanoic acid (PFBA) and perfluoropentanoic acid (PFPeA) were detected in the surface water samples taken adjacent to the landfill, suggesting that the landfill contributed to these compounds. PFBA was the dominant PFAS in the groundwater and sediments. The concentrations of long-chain perfluoroalkyl carboxylic acids (PFCAs) (C8-C12) in the sediment samples correlated significantly with the TOC, Al2O3 and Fe2O3 contents. The partitioning behaviors of PFCAs in the water-sediment system varied depending on the CF2 moiety units. For the long-chain PFCAs, positive correlations between the average LogKd and the number of CF2 moieties were found to be statistically significant, whereas negative correlations were observed for the short-chain PFCAs (C4-C7). The ratios of short-chain analogues and emerging alternatives versus their respective legacy PFOA and perfluorooctane sulfonate (PFOS) in surface water suggested an increasing trend of short-chain analogues, such as PFBA. The potential health risks of PFOS and PFOA, determined by calculating the estimated daily intake (EDI), were found to be negligible via the drinking groundwater exposure pathway, but more comprehensive studies on the human health risks of PFASs from landfills are essential.