POLY- AND PERFLUOROALKYL SUBSTANCES (PFASS) IN GROUNDWATER FROM TWO LEGACY SOURCES ON CAPE COD, MA – WHAT ARE THE NATIONAL IMPLICATIONS? (Invited Presentation)

Poly- and perfluoroalkyl substances have been in use for their unique oleophobic and hydrophobic properties since the 1950s and are persistent widespread environmental contaminants that have been associated with adverse health effects. In 2016, the U.S. Environmental Protection Agency published provisional drinking water guidelines of 70 nanograms per liter for perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) combined, which are two frequently detected PFAS compounds in the environment. However, more than 3,000 PFASs are on the market, and there is a paucity of data on their environmental transport properties and associated human and environmental health impacts. To address this gap, we investigated the fate and transport of PFASs in a sand and gravel aquifer that is the sole source of drinking water on Cape Cod. The PFAS plume originated primarily from a fire training area on a military base where PFAS-containing aqueous film-forming foam was used as a fire suppressant from 1970 to 1985. There are more than 500 other fire training areas across the U.S., raising the concern for widespread associated PFAS contamination. In this study, we analyzed 148 groundwater samples along a 1200-m-long transect aligned in the direction of groundwater flow away from the fire training area. The fire training area was shown to be a continuing source of PFASs to groundwater after about 20 years of inactivity. Persistent PFAS inputs to the groundwater in a region characterized by glacial sandy, low-organic-content sediments indicates that other fire-training areas may also adversely impact water quality over long time periods if left untreated. Furthermore, we found that some precursors to commonly studied terminal products (like PFOS and PFOA) are readily transported at the site, suggesting that conventional analytical methods are underestimating the total aqueous PFAS burden. Ongoing field studies indicate that a portion of this PFAS plume discharges to a glacial kettle lake about 1.2 km from the fire training area. Lake water contaminated by PFASs then discharges back into the groundwater on the downgradient side of the lake and expands the area of PFAS contamination in the drinking-water aquifer. Current work aims to understand the fate of precursors as they are transported across the groundwater/lake boundary.