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Estuarine Fate of Aqueous Film Forming Foam Applied in an Urbanized Watershed
Katz, D., M. Cantwell, C. Gardner, A. Robuck, AND R. Lohmann. Estuarine Fate of Aqueous Film Forming Foam Applied in an Urbanized Watershed. SETAC North America, Toronto, Ontario, CANADA, November 03 - 07, 2019.
Per- and poly-fluorinated alkanoic substances (PFAS) enter the environment from a variety of sources. The use of aqueous film forming foams (AFFF) to prevent or extinguish fires is a major route for highly concentrated PFAS discharges to the environment. Deployments of AFFF are infrequent and researchers are rarely positioned to mobilize within a relevant timeframe to study the transport and fate of the AFFF constituents immediately following usage. This study represents a unique situation where researchers had sampling collection planned prior to the use of an AFFF. Results of the study showed discharge to the environment directly via stormwater drains and from the local wastewater treatment plant via combined sewers. A novel chemical and major component of the foam was tentatively identified and measured in both the concentrated AFFF and the environment. High concentrations of PFAS were spatially limited due to rapid dilution from surface river flows and tidal action in the Providence River.
Aqueous film forming foams (AFFF) used for firefighting often contain unidentified forms of per- and polyfluoroalkanoic substances (PFAS) for which commercial standards are unavailable. The application of AFFF during emergency situations typically leads to the release of these compounds into the environment. First responders in Providence, RI, USA applied an AFFF for vapor suppression and ignition prevention after a gasoline tanker truck overturned spilling its fuel. Due to the proximity of the incident to the Providence River in the upper reaches of Narragansett Bay (NB), an unknown amount of gasoline and dilute AFFF entered the estuary via surface runoff and stormwater drains. Bay water samples near the spill were collected approximately 12 hours after the incident and analyzed for PFAS. In addition, a total oxidizable precursor (TOP) assay was performed on water samples and the AFFF concentrate. Samples were enriched by solid phase extraction – weak anion exchange and quantified by UPLC-MS/MS using isotope dilution. Minor increases in PFAS concentrations were observed relative to pre- and post-spill samples at sites nearest to the incident. However, the TOP assay showed significant increases in perfluorocarboxylic acids in samples collected immediately after the incident. The highest values were observed near the local wastewater treatment plant outfall, likely due to transport from the incident site via combined sewer-stormwater drains. Minor increases in linear alkyl PFAS concentrations relative to other time periods were likely the result of degradation of the AFFF component during the wastewater treatment process. A candidate compound, 6:2 fluorotelomermercaptoalkylamido sulfonate (6:2-FTSAS), was identified as a major foam component. Characteristic precursor/product masses of 6:2 FTSAS were observed in water samples and the presence of the compound was further confirmed by the observation of characteristic masses of the 6:2-FTSAS-sulfoxide degradation product. Peak areas of 6:2-FTSAS corresponded with observed increases in the TOP results. Due to river flow and tidal action, elevated levels of PFAS were limited to a confined area of the Providence River.