Aftermath of a major firefighting foam spill in Brunswick, Maine: Spatiotemporal dynamics of per- and polyfluoroalkyl substances in the downstream surface waters

On August 19, 2024, 5,500 L of per- and polyfluoroalkyl substances (PFAS)-based aqueous film-forming foam (AFFF) spilled into the watershed near Brunswick Executive Airport in Maine, USA. This study investigates the immediate impact of the largest PFAS spill in the state's history on nearby aquatic ecosystems. Over 11 days, PFAS were sampled from nine surface waters, detecting 18 PFAS, predominantly perfluorooctanesulfonic acid (PFOS). A significant reduction in PFAS levels occurred within days due to clean-up efforts and natural attenuation ( e.g. , dilution, adsorption, and aerosolization), in addition to downstream transport. Kruskal-Wallis and Steel-Dwass tests revealed significant spatial variability in PFAS, with PFOS, perfluorohexanesulfonic acid, and perfluoroalkyloctanoic acid remaining elevated near the spill but declined by 99.9 % at the Harpswell Cove estuary 3.2 km south of the spill. The rapid PFAS spread poses risks to the downstream environments. This study provides insights into post-spill PFAS dynamics and highlights the urgency of minimizing PFAS-based AFFF use and spills, and further research into long-term ecosystem and human health risks associated with PFAS contamination. The aftermath of a major AFFF spill was analyzed to provide insights into immediate spatiotemporal distribution of PFAS. • Brunswick Airport spill was 5500 L AFFF causes Maine’s largest PFAS contamination. • The analysis of the blend water from the spill site revealed 12 PFAS. • Total PFAS levels peaked at 1231,860 ng/L; and declines observed post-spill. • Study reveals rapid PFAS transport to Harpswell Cove over 11 days post-spill.