Centurial Persistence of Forever Chemicals at Military Fire Training Sites

Abstract

Drinking water contamination by per- and polyfluoroalkyl substances (PFAS) is widespread near more than 300 United States (U.S.) military bases that used aqueous film-forming foams (AFFF) for fire training and firefighting activities. Much of the PFAS at these sites consist of precursors that can transform into terminal compounds of known health concern but are omitted from standard analytical methods. Here, we estimate the expected duration and contribution of precursor biotransformation to groundwater PFAS contamination at an AFFF-contaminated military base on Cape Cod, Massachusetts, United States, by optimizing a geochemical box model using measured PFAS concentrations from a multidecadal time series of groundwater and a soil survey in the source zone. A toolbox of analytical techniques used to reconstruct the mass budget of PFAS showed that precursors accounted for 46 ± 8% of the extractable organofluorine (a proxy for total PFAS) across years. Terminal PFAS still exceed regulatory limits by 2000-fold decades after AFFF use ceased. Measurements and numerical modeling show that sulfonamido precursors are retained in the vadose zone and their slow biotransformation into perfluoroalkyl sulfonates (half-life > 66 yr) sustains groundwater concentrations of perfluorobutane sulfonate (PFBS) and perfluorohexane sulfonate (PFHxS). The estimated PFAS reservoir in the vadose zone and modeled flux into groundwater suggest PFAS contamination above regulatory guidelines will persist for centuries without remediation.

The Total Oxidizable Precursor (TOP) Assay as a Forensic Tool for Per- and Polyfluoroalkyl Substances (PFAS) Source Apportionment

“…Solid and aqueous samples from AFFF-impacted sites and WWTPs separated along PC1 (Figure B) with solid samples more associated with negative PC1 values indicating relative enrichment in precursors compared to aqueous samples. Many precursors have cationic moieties and tend to sorb strongly to natural organic matter, which is net negatively charged and can act as a source of PFAS contamination. ,, No separation by matrix was observed along PC2, enabling separation of sources regardless of sample matrix. Source separation along PC2 was driven by PFOS, PFHxS, PFBA, ΔPFHxA and ΔPFBA, suggesting that these analytes have greatest forensic value when considering samples from solid and aqueous matrices.…”

Binding of Per- and Polyfluoroalkyl Substances (PFAS) to Serum Proteins: Implications for Toxicokinetics in Humans

“…Targeted PFAS in this study were measured using an online SPE method on an Agilent (Santa Clara, CA) 6460 triple quadrupole liquid chromatography–tandem mass spectrometer at Harvard University. , Additional information on chemical analysis is summarized in Section S4, SI. Linear and branched isomers were individually measured, and the reported distribution coefficients integrate the sum of isomers in the mixture.…”

Interlaboratory Comparison of Extractable Organofluorine Measurements in Groundwater and Eel (Anguilla rostrata): Recommendations for Methods Standardization

“…The EOF fraction accounted for by PFAA in groundwater agrees with the historical average measured from the same groundwater sampling port (USGS well MA-SDW 425-0063) between 2002 and 2021 reported in previous work. 39 That work demonstrated PFAA accounted for 54 ± 16% of EOF and that remaining unquantified fraction were PFAA precursors measured by the total oxidizable precursor assay.…”