Vermont-wide assessment of anthropogenic background concentrations of perfluoroalkyl substances in surface soils

Shallow surface soils from 66 suburban sampling locations across Vermont were analyzed for 17 different per-fluoroalkyl acids (PFAA). PFAA were detected in all 66 surface soils, with a total concentration of PFAA ranging from 540 to 36,000 ng/kg dry soil weight (dw). Despite the complexity of site-specific factors, some general trends and correlations in PFAA concentrations were observed. For instance, perfluoro-1-octanesulfonate (PFOS) dominated in all soil samples while seven other PFAA, including perfluoro-n-nonanoic acid, perfluoro-n-octanoic acid, perfluoro-n-hexanoic acid, perfluoro-n-heptanoic acid, perfluoro-n-decanoic acid, perfluoro-n-undecanoic acid, perfluoro-1-butanesulfonate, and perfluoro-1-hexanesulfonate (PFNA, PFOA, PFHxA, PFHpA, PFDA, PFUnDA, and PFBS, respectively), were identified at more than 50 % of the locations. Perfluoroalkyl carboxylic acids (PFCA) showed a positive correlation with total organic carbon, whereas no clear correlation was observed for perfluoroalkyl sulfonate acids (PFSA). In addition, variations in geographical distributions of PFAA were observed, with relatively higher total PFAA in northern regions when compared to Southern Vermont. Moreover, PFHxA, PFNA, PFDA, PFUnDA, PFOS, and total PFAA were positively correlated to land-use types in Northern Vermont. These results are useful for understanding unique behaviors of PFCA vs. PFSA in geospatially distributed surface soils and for providing anthropogenic background data for setting PFAS cleanup standards for surface soils.

Automated summary

Surface soils from 66 suburban locations in Vermont were analyzed for PFAA compounds, and some general trends and correlations were observed in their concentrations. PFOS was found to dominate in all soil samples, while seven other PFAA compounds were identified at more than 50% of the sites. PFCA showed a positive correlation with total organic carbon, whereas no clear correlation was observed for PFSA. The geographical distribution of PFAA compounds was also found to vary, with higher concentrations in northern regions compared to southern Vermont. These findings provide useful information for understanding the behavior of PFCA and PFSA in geospatially distributed surface soils, as well as for establishing cleanup standards.