Vertical Distribution and Emission Characteristics of Per- and Polyfluoroalkyl Substances in a Municipal Solid Waste Landfill
This study systematically investigated the occurrence and vertical distribution of per- and polyfluoroalkyl substances (PFAS) in solid waste, leachate, and surrounding groundwater at a municipal solid waste landfill in Fuyang City, Anhui Province, China. A total of 23 PFAS were detected in solid waste, with total concentrations (∑PFAS) ranging from 7.95 to 172.28 ng·g⁻¹. Trifluoroacetic acid (TFA), an ultrashort-chain PFAS, was ubiquitous, contributing on average 59% to the total PFAS mass. PFAS composition varied with depth: long-chain PFAS dominated in middle and upper layers, while short-chain and ultrashort-chain PFAS were more abundant in deeper layers, indicating enhanced downward migration of shorter-chain compounds. Sulfonic acid PFAS exhibited increasing relative abundance with depth. Leachate ∑PFAS concentration was 14.35 μg·L⁻¹, dominated by short-chain compounds such as PFPrS and PFBS, consistent with the composition in bottom-layer waste. Groundwater surrounding the landfill contained multiple PFAS, with concentrations decreasing with distance from the landfill, confirming the landfill as a source of PFAS to the surrounding environment. Multivariate analyses (PCoA and Bray–Curtis dissimilarity) revealed that some groundwater samples closely resembled leachate in PFAS composition, suggesting direct impact via leachate migration. These findings underscore the role of landfills as significant reservoirs and sources of PFAS, particularly ultrashort-chain compounds, and highlight the need for improved leachate management to mitigate groundwater contamination.