Depth Profiles of PFAS in Community Garden and Agricultural Soils

Abstract

Despite growing evidence of PFAS contamination in agricultural soils, urban community gardens have received little attention. However, these gardens may become contaminated with PFAS through inputs such as compost, fertilizers, and urban runoff. In this study, thirteen out of forty targeted PFAS, representing three PFAS classes, were detected in a community garden soil, with a total PFAS concentration of 3,987±146 ng kg⁻¹. Interestingly, total PFAS in the community garden soil was 2.6 times of the investigated agricultural soils (1,523±25 ng kg⁻¹). PFAS exhibited a clear vertical distribution in both community garden and agricultural soils, with concentrations highest at the surface (0-5 cm) and decreasing with depth. This distribution pattern of PFAS was significantly influenced by soil physicochemical properties, including dissolved organic matter characteristics, and its humic- and fulvic-like components, as well as the soil’s cation exchange capacity. Furthermore, PFAS distribution patterns in soils, when compared with those in compost and landfill organics from our previous studies, exhibited distinct, matrix-specific depth profiles. Distinct distribution patterns of PFAS may offer useful insights to guide risk assessment and develop mitigation strategies in future studies.