Vertical Distribution and Emission Characteristics of Per- and Polyfluoroalkyl Substances in a Municipal Solid Waste Landfill

• • Solid waste in the landfill contained 23 PFAS with ∑PFAS concentrations from 7.95 to 172.28 ng·g⁻¹; TFA alone accounted for 59% of total PFAS mass, underscoring the dominance of ultrashort-chain compounds in landfill waste and their potential for environmental release. • • Vertical profiling revealed that short-chain and ultrashort-chain PFAS (e.g., TFA, PFPrS) preferentially migrate to deeper layers, while long-chain PFAS remain in upper layers, indicating chain-length-dependent mobility that governs subsurface contamination pathways. • • Leachate exhibited ∑PFAS of 14.35 μg·L⁻¹, with PFPrS and PFBS as major monomers, mirroring the composition of bottom-layer waste and confirming leachate as a primary vector for PFAS export from landfills. • • Groundwater samples near the landfill showed PFAS concentrations decreasing with distance, and PCoA/Bray–Curtis analysis identified specific wells (GW26, GW17) with PFAS profiles highly similar to leachate, providing direct evidence of leachate impact on groundwater and the need for enhanced containment measures.