PFAS contamination in agricultural systems near an active war zone: Sources, distribution, and crop uptake

Active war zones have recently become part of many people's daily lives. In addition to their harm, active war zones may also serve as potential hotspots for per- and polyfluoroalkyl substances (PFAS) due to the extensive use of munitions. Nevertheless, their impact on neighboring agricultural environments remains largely understudied. Here, we report the occurrence and distribution of PFAS in agricultural and uncultivated soils, as well as in potato plants, along a spatial gradient from an active war zone. We hypothesized that if military emissions were a dominant local source of PFAS, their concentrations and compositional profiles in soils and plants would exhibit a spatial gradient. Foliage analysis indicated a potential atmospheric pathway of PFAS contamination that may be related to conflict activities or regional air pollution; leaves were highly concentrated with volatile short-chain PFAS (predominantly perfluorobutanoic acid [PFBA]), independent of their soil concentrations. Although leaves exhibited significant accumulation of volatile PFAS, they were largely absent from the edible tubers. Soil data indicate that agricultural soil contamination was dominated by legacy sulfonates (Perfluorooctanesulfonic acid [PFOS] and Perfluorohexanesulfonic acid [PFHxS]) introduced via treated wastewater irrigation and biosolids application, which effectively masked potential PFAS deposition from atmospheric deposition originating from military conflict, and/ or industrial emissions. Uncultivated soils exhibited a carboxylate-rich profile theorized to resemble incomplete combustion products of fluoropolymers. However, the lack of a spatial gradient suggests a background signal, indicating that air deposition of PFAS from warfare regions is likely confined to sites of detonation. This study suggests that while soil contamination (agricultural and uncultivated) reflects long-term inputs, active war zones may introduce or mobilize volatile PFAS that, although masked in soils, are preferentially intercepted by vegetation.