Using Regulatory Classifications to Assess the Impact of Different Land Use Types on Per- and Polyfluoroalkyl Substance Concentrations in Stormwater Pond Sediments

Abstract

Current research on the fate and transport of per- and polyfluoroalkyl substances (PFAS) has primarily focused on point-source releases, with less focus on nonpoint-source releases, such as stormwater runoff. In this study, 51 PFAS were investigated in sediment collected from two locations at nine stormwater ponds classified by different land-use types. PFAS concentrations were then related to two different land-use disturbance indicators, the Landscape Development Intensity (LDI) index and the Florida Department of Transportation (FDOT) road type functional classification, to discern a potential metric for estimating PFAS burden by using the proximity to and different types of anthropogenic activity. Of the 51 compounds analyzed, 28 in total were quantified with concentrations ranging from 7.2 to $\mathrm{4,800}\mathrm{ng}{\mathrm{kg}}^{-1}$ . Perfluorinated carboxylic acids were the most commonly identified class of PFAS, as perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUdA), perfluorododecanoic acid (PFDoA), and perfluorotridecanoic acid (PFTrDA) were all found at eight out of nine sites, as well as perfluorooctane sulfonic acid (PFOS), a perfluorinated sulfonic acid. Within the framework of this study, the LDI index did not appear to be significantly correlated to PFAS burden, whereby only the 0.4 km radius of the LDI weighted average resulted in a potential metric for the lowest PFAS contaminated sites (which had correspondingly low LDI weighted means). The FDOT functional classification was a better predictor across all sites for PFAS burden, in which a significant difference was found between the number of PFAS detected at rural and urban sites. Most notably, perfluorohexanoic acid (PFHxA) concentrations were found to be significantly different between rural and urban sites. Moving forward, the potential of utilizing road type functional classification should be explored as a predictive tool to help better prioritize stormwater pond monitoring for PFAS.