Persistence of Perfluoroalkyl Acid Precursors in AFFF-Impacted Groundwater and Soil

Abstract

Several classes of polyfluorinated chemicals that are potential precursors to the perfluorinated carboxylates and sulfonates are present in aqueous film-forming foams (AFFF). To assess the persistence of these AFFF-derived precursors, groundwater, soil, and aquifer solids were obtained in 2011 from an unlined firefighter training area at a U.S. Air Force Base where AFFF was regularly used between 1970 and 1990. To measure the total concentration of perfluorinated carboxylate and sulfonate precursors in archived AFFF formulations and AFFF-impacted environmental samples, a previously developed assay that uses hydroxyl radical to oxidize precursors to perfluorinated carboxylates was adapted for these media. This assay was employed along with direct measurement of 22 precursors found in AFFF and a suite of other poly- and perfluoroalkyl substances (PFASs). On a molar basis, precursors accounted for 41-100% of the total concentration of PFASs in archived AFFF formulations. In the training area, precursors measured by the oxidation assay accounted for an average of 23% and 28% of total PFASs (i.e., precursors and perfluorinated carboxylates and sulfonates) in groundwater and solids samples, respectively. One precursor in AFFF, perfluorohexane sulfonamide amine, was observed on several highly contaminated soil and aquifer solids samples, but no other precursors present in AFFF formulations were detected in any samples at this field site. Suspected intermediate transformation products of precursors in AFFF that were directly measured accounted for approximately half of the total precursor concentration in samples from the training site. The fraction of PFASs consisting of perfluorinated carboxylates and sulfonates was greater in groundwater and solid samples than in any archived AFFF formulations, suggesting that much of the mass of precursors released at the site was converted to perfluorinated carboxylates and sulfonates. The precursors that have persisted at this site may generate significant amounts of additional perfluorinated carboxylates and sulfonates upon remediation of contaminated groundwater or aquifer solids.

Survey of perfluoroalkyl acids (PFAAs) and their precursors present in Japanese consumer products

“…In the study conducted in Norway, greater concentrations of RPFASs were found in waterproofing agents, which can be regarded as the same category as sprays for fabrics and textiles in this study, with the exception of aqueous firefighting foams (Houtz et al, 2013). In the study conducted in Germany, greater concentrations of FTOHs (up to 396 lg mL À1 ) were found in the category ''lubricants'' (LU 1 and LU2) (Fiedler et al, 2010).…”

Simultaneous qualitative and quantitative analysis of fluoroalkyl sulfonates in riverine water by liquid chromatography coupled with Orbitrap high resolution mass spectrometry

“…Therefore, PFOS and its salts have been voluntarily phased-out by its major manufacturers and have been added to list of the Stock Convention on Persistent Organic Pollutants (Annex B, UNEP) [8]. Other polyfluorinated substances, such as 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFAES) and fluorotelomer sulfonates (FTSs) were also found in aqueous systems due to alternative usages [9,10].…”

Aquatic hazard, bioaccumulation and screening risk assessment for 6:2 fluorotelomer sulfonate

“…Fluorinated surfactants based on fluorotelomer thiol ( (Falk, 1984), e.g., F(CF 2 ) n CH 2 CH 2 SCH 2 CH(OH) CH 2 N + H(CH 3 )CH 2 CO 2 À ) and sulfonyl chemistry ( (Bertocchio and Foulletier, 1971) e.g., F(CF 2 ) n CH 2 CH 2 SO 2 NHCH 2 CH 2 N + (CH 3 ) 2 CH 2 CH 2 CO 2 À ) have also been used in AFFF. As a result of AFFF containing these fluorinated surfactants being used at fire training facilities to control and extinguish major Class B (i.e., flammable, combustible liquids and gases) fires, environmental degradation products such as PFSAs and fluorotelomer sulfonic acids (FTSAs) have been found in ground water and soil (Backe et al, 2013;Houtz et al, 2013). The perfluoroalkane sulfonyl surfactants degrade to the corresponding PFSA, e.g., PFOS, PFHxS, and PFBS (Moody and Field, 2000;Moody et al, 2003;Rhoads et al, 2008).…”