Per- and polyfluoroalkyl substances (PFASs) are anthropogenic chemicals used in manufacturing processes and end products to provide resistance to heat, oil, grease, and water. PFASs are unique in that they possess both hydrophobic (water-repelling) and oleophobic (oil-repelling) properties. In the 1960s, the Navy, Air Force, and Army widely adopted their use in aqueous film-forming foams (AFFF) for fighting aircraft fuel fires. Although AFFF-contaminated sites have the highest recorded PFAS concentrations to date, PFASs in the environment are not solely associated with firefighter training areas. Lower levels of PFASs are found in consumer products (e.g., nonstick materials, packaging coatings, and textile protectants), industrial applications (e.g., electroplating), municipal wastewater, and landfill leachates. The potential toxicity of PFASs has only recently become known, and PFASs are identified as emerging contaminants by the Department of Defense (DoD).
The objective of this project is to: (1) characterize the total footprint of PFAS contamination at field sites by total fluorine and individual PFAS analysis to enable fingerprinting of AFFF-based sources as compared to non-AFFF sources; (2) determine the nature and extent of PFAS source areas at Navy and other DoD sites; and (3) identify factors such as soil characteristics (organic carbon content and ion exchange capacity) and groundwater redox potential that affect the transport of PFASs that vary in carbon chain length and head group character (anionic, cationic, zwitterionic, and neutral).
Three sites with known PFAS contamination of soil and groundwater, likely source zone(s), and known or potential surface water impacts, will be selected for detailed investigation, including high-resolution sampling of source areas, groundwater, surface water, soil, and sediment, to evaluate the source, nature, and extent of the PFAS contamination. State-of-the-art analytical techniques including total fluorine by particle induced gamma ray emission (PIGE) spectroscopy and liquid chromatogram tandem mass spectrometry (LCMS/MS) of individual PFASs will provide the robust dataset needed to fingerprint source, identify source zones, delineate plume boundaries, estimate attenuation rates and retardation factors, and estimate exposure potential.
The information generated by this study will help remedial project managers (RPMs) develop more accurate conceptual site models (CSMs) by identifying PFASs that define source zones and the composition of plumes. These CSMs can help inform the selection of mitigation and remediation strategies, not just at the sites studied, but at all DoD sites. Disseminating information and analytical methodologies to contract laboratories on the highest concentration PFASs that occur at high frequency will translate to increased capability to meet RPM/contract needs for high quality field data of PFASs of potential concern. Strategic use of PIGE, which is high throughput and cost effective, in drilling wells, delineating plume boundaries, and proportioning more expensive analytical testing will translate to immediate DoD cost savings when characterizing additional sites. Detailed plume characterization will provide information on transformation pathways and estimates of natural attenuation under prevailing groundwater redox conditions that can be generalized across military sites contaminated with AFFF. The potential for human and ecological exposure will be estimated by assessing the transport of these compounds in the environment. (Anticipated Project Completion - 2019)
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