Key Takeaways & Executive Findings
- •• • 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.
Abstract
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.
1. Introduction
Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals characterized by their exceptional thermal and chemical stability, as well as hydrophobic and oleophobic properties. These attributes have led to their widespread use in consumer and industrial products, including firefighting foams, non-stick cookware, and water-repellent textiles. However, the same properties render PFAS highly persistent in the environment, and certain congeners exhibit bioaccumulative and toxic effects. As a result, PFAS have emerged as a global concern among emerging contaminants. Landfills, as the final repository for a substantial fraction of municipal solid waste, receive large quantities of PFAS-containing products. Over time, physical, chemical, and biological processes within the landfill can mobilize PFAS, leading to their release into leachate and subsequently into surrounding soil and groundwater. Despite this, the vertical distribution and emission characteristics of PFAS within landfill systems remain poorly characterized, particularly for ultrashort-chain compounds such as trifluoroacetic acid (TFA), which are often overlooked due to analytical challenges.
Previous studies have documented elevated PFAS concentrations in landfill leachate, but the fate and transport of PFAS across the solid waste–leachate–groundwater continuum are not fully understood. The present study addresses this gap by conducting a comprehensive field investigation at a landfill in Anhui Province, China. By analyzing PFAS in solid waste at various depths, leachate, and surrounding groundwater, we aim to elucidate the vertical distribution patterns and identify the key factors controlling PFAS migration. The findings provide critical insights into the environmental behavior of PFAS in landfills, particularly the role of chain length in mobility, and offer a scientific basis for developing targeted risk management strategies to mitigate PFAS contamination of groundwater resources.
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CHEN Tianyu, HE Xiaosong, SUN Yue, YU Shiyang, GUO Yanli, HE Anen, LI Juan, LYU Jitao, WANG Yawei (2026). Vertical Distribution and Emission Characteristics of Per- and Polyfluoroalkyl Substances in a Municipal Solid Waste Landfill. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2026022702
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Frequently Asked Questions
What are the dominant PFAS compounds in landfill solid waste, and how does their composition vary with depth?
In the studied landfill, 23 PFAS were detected in solid waste, with total concentrations ranging from 7.95 to 172.28 ng·g⁻¹. Trifluoroacetic acid (TFA) was the most abundant, contributing on average 59% to the total PFAS mass. Composition varied with depth: long-chain PFAS (e.g., perfluorooctanoic acid) were more prevalent in middle and upper layers, while short-chain and ultrashort-chain PFAS (e.g., TFA, perfluoropropane sulfonate) increased in relative abundance in deeper layers. This indicates that shorter-chain PFAS have higher mobility and migrate downward more readily.
How does the PFAS concentration in leachate compare to that in solid waste, and what are the implications for environmental release?
Leachate ∑PFAS concentration was 14.35 μg·L⁻¹, which is several orders of magnitude higher than the concentrations in solid waste (ng·g⁻¹). The leachate was dominated by short-chain compounds such as PFPrS and PFBS, similar to the composition in bottom-layer waste. This high concentration in leachate, combined with its mobility, makes leachate a primary vector for PFAS release from landfills to surrounding environments. The study found that groundwater near the landfill contained PFAS, with concentrations decreasing with distance, confirming the landfill as a source.
What evidence indicates that groundwater contamination is directly linked to leachate from the landfill?
Principal coordinate analysis (PCoA) and Bray–Curtis dissimilarity analysis revealed that two groundwater samples (GW26 and GW17) had PFAS composition profiles highly similar to that of the leachate, with significantly lower dissimilarity compared to other groundwater samples. This suggests that these wells are directly impacted by leachate, likely due to local liner failure or enhanced migration during wet seasons. The findings underscore the need for robust containment and leachate management to prevent groundwater contamination.
What is the significance of ultrashort-chain PFAS like TFA in landfill systems, and why are they often overlooked?
Ultrashort-chain PFAS, such as TFA, are highly mobile and persistent, yet they are frequently not included in routine monitoring due to analytical difficulties. In this study, TFA was detected in all solid waste samples and accounted for 59% of the total PFAS mass, indicating that it is a major component of landfill PFAS burden. Their high mobility means they can easily leach into groundwater, posing a potential risk to drinking water sources. Therefore, monitoring and regulation should include ultrashort-chain PFAS to fully assess the environmental impact of landfills.
What are the practical implications of this study for landfill management and PFAS risk mitigation?
The study demonstrates that landfills are significant sources of PFAS to the environment, particularly through leachate. The vertical distribution patterns suggest that short-chain PFAS migrate deeper and may eventually reach groundwater. Therefore, effective leachate collection and treatment systems, as well as proper liner integrity, are critical to minimize PFAS release. Additionally, the presence of PFAS in groundwater near the landfill indicates that monitoring programs should include a wide range of PFAS, including ultrashort-chain compounds, to adequately assess contamination and protect public health.
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