Induced Polarization Signatures at Former Fire Training Areas Contaminated with Aqueous Film Forming Foam (AFFF)
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The release of PFAS containing aqueous film-forming foam (AFFF) constituents from former firefighting training areas leads to soil and groundwater contamination, threatening human health and the environment. Non-invasive field methods are needed to effectively characterize soil PFAS concentrations and textural variations, specifically soil surface area, and to model long-term PFAS leaching from these source zones. Geophysical methods, such as induced polarization (IP), can characterize the electrical properties of the subsurface. Preliminary research suggests that IP has the potential to detect variations in sorbed AFFF constituents. However, IP is also sensitive to soil texture (e.g., surface area) and textural heterogeneities at field sites, which may mask signals from sorbed AFFF constituents. This study investigated the contributions of AFFF contamination versus soil surface area to IP signals observed across two former firefighting training areas. Samples were collected to assess the statistical significance of IP sensitivity in distinguishing AFFF sorption from soil surface area variations through laboratory analysis. Although our IP measurements could not map spatial variations in soil PFAS concentrations at these sites, the ability to image field-scale surface area highlights the potential importance and utility of geophysics in understanding PFAS leaching from contaminated source zones.