Induced Polarization Characterization of an AFFF Source Zone
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The characterization of aqueous film-forming foam (AFFF) source zones resulting from former fire training activities is required to assess spatial variations in the concentrations of contaminants, such as per- and poly-fluoroalkyl substances (PFAS), and to support remediation of AFFF-impacted sites. Recent research indicates the potential for using spectral-induced polarization (SIP) to delineate PFAS contamination from an AFFF source zone in a region of simple lithology. However, more extensive geophysical investigations are necessary to further explore the uses of induced polarization (IP) to identify AFFF constituents sorbed onto the soil, particularly at sites with complex lithology. This study aims to explore whether IP is sufficiently sensitive to variations in PFAS concentrations observed across multiple AFFF source zones. Samples were collected from three AFFF source zones to determine if a statistically significant relationship between AFFF constituents and SIP response exists. In-situ field measurements were performed to determine whether field-scale SIP and time domain-induced polarization (TDIP) methods could delineate spatial variations in soil PFAS concentrations across the sites. Our findings indicate that AFFF constituents associated with the soil surface are unlikely to exhibit a direct correlation with soil PFAS concentration in disturbed/remediated sites where variations in the physical properties of the soil are likely to dominate the SIP response.