Science Inventory

Transport and Fate of Aqueous Film Forming Foam in an Urban Estuary

Citation:

Katz, D., Julia Sullivan, K. Rosa, C. Gardiner, A. Robuck, R. Lohmann, C. Kincaid, AND M. Cantwell. Transport and Fate of Aqueous Film Forming Foam in an Urban Estuary. ENVIRONMENTAL POLLUTION. Elsevier Science Ltd, New York, NY, 300:118963, (2022). https://doi.org/10.1016/j.envpol.2022.118963

Impact/Purpose:

Per- and polyfluoroalkanoic substances (PFAS) have been used in many products and recently questions have been raised about their safety, fate, transport and persistence in the environment. The use of aqueous film forming foams (AFFF) during some types of fire-fighting emergencies and training leads to the release of PFAS into the environment. AFFF was applied during a fuel spill in Providence, RI in October 2018, and as a result an unknown quantity of gasoline and AFFF entered the Narragansett Bay estuary. Water samples near the spill were collected approximately 12 hours after the incident along a 6 station transect. Routine analysis only showed minor increases in the concentrations of 24 specific and commonly analyzed PFAS after the spill. After performing a chemical reaction on the water samples significant increases in total PFAS at the time of the spill were revealed, indicating the presence of PFAS precursor compounds in the AFFF and also NB water samples. The concentration of one compound identified as a major component of the AFFF corresponded with increases in PFAS precursors, making this compound useful as a tracer of AFFF in surrounding waters. Observed PFAS concentrations were also compared to a computer simulation of AFFF dilution in the affected area, and results confirmed rapid dissipation of AFFF components with distance from the spill. However, modeled results did not capture possible secondary releases of AFFF from local stormwater and sewer infrastructure, as observational data suggest. The multiple lines of evidence of PFAS presence in surface waters permitted a better assessment of the potential environmental impacts from products such as AFFF for which chemical composition is largely unknown.

Description:

The deployment of aqueous film forming foams (AFFF) used for firefighting during emergencies and training often releases per- and polyfluoroalkyl substances (PFAS) into the environment. In October 2018, first responders in Providence, RI, USA applied an AFFF during a fuel spill. Due to the proximity of the incident to the upper reaches of Narragansett Bay (NB), an unknown quantity of gasoline and AFFF entered the estuary via surface runoff and stormwater drains. Water samples near the spill were collected approximately 15 h after the incident and analyzed for 24 PFAS. Minor increases in measured PFAS concentrations were observed relative to pre- and post-spill samples at monitoring sites near the incident, except 6:2-fluorotelomer sulfonate (6:2-FTS) that peaked post-spill (max 311 ng/L). After performing the total oxidizable precursor (TOP) assay on water samples and the AFFF concentrate, significant increases in perfluorocarboxylic acids (PFCAs) were observed. One compound, 6:2 fluorotelomer mercaptoalkylamido sulfonate (6:2-FTSAS), was identified as a major component of the AFFF used. Peak areas of 6:2-FTSAS and the degradation product 6:2-FTSAS-sulfoxide corresponded to observed increases in the TOP assay results and were useful as tracers of AFFF in surrounding waters. Elevated levels of PFAS at the time of sampling were limited to a confined area of the Providence River due to river flow and tidal action. Observed concentrations were also compared to hydrodynamic model results, and results confirmed rapid dissipation of AFFF components with distance from the spill. However, modeled results did not capture possible secondary releases of AFFF from local municipal stormwater and sewer infrastructure, as observational data suggest. The multiple lines of evidence of PFAS present in surface waters permitted a better assessment of the potential environmental impacts from products such as AFFF for which the chemical composition is largely unknown.