Characteristics of aqueous film forming foam (AFFF) sites impacted with per- and polyfluoroalkyl substances (PFAS): A...

A meta-analysis of 37 military aqueous film-forming foam (AFFF) sites was conducted to gain insights into the fate and transport of seven key perfluoroalkyl acids (PFAAs): PFOS, PFOA, PFHxS, PFHxA, PFBS, PFBA, and PFNA. Specifically, this study aims to examine occurrence of the seven PFAAs in soil and groundwater at AFFF source zones and understand PFAA plume characteristics as well as estimate plume lengths. Based on an evaluation of these PFAAs in soil samples collected in the source zone, the highest concentrations predominantly occur within the top one meter (m) below ground surface (bgs). PFOS and PFOA are the major PFAA contributors in soil at source zones, whereas groundwater exhibits a more diverse concentration distribution. Inferred Current Plume Lengths are presented for the seven PFAAs, with median plume lengths ranging from 220 to 800 m. Finally, an exceedance magnitude assessment was conducted to evaluate the potential contribution of each studied PFAA to the exceedance of groundwater regional screening levels (RSLs) or maximum contaminant levels (MCLs). Results indicate that at typical AFFF sites, PFOS, PFOA, and PFHxS generally contribute 99 % of the estimated exceedance magnitude, whereas short-chained PFAAs (PFHxA, PFBS, and PFBA) contribute <1 %.