Sheng Dong is currently a postdoctoral associate in Biological and Environmental Engineering at Cornell University. Sheng has a Ph.D. in Civil and Environmental Engineering from Auburn University, with concentrations in biotransformation of per- and polyfluoroalkyl substances (PFAS), particularly perfluoroalkyl acids (PFAA) precursors, and the response of microbial communities to PFAS contamination. Her research interests include ecological impact of environmental contaminants, transformation kinetics and mechanisms of emerging contaminants, and innovative bioremediation technology.
Transformation of Electrochemical Fluorination-based Per- and Polyfluoroalkyl Substances in Aqueous Film-Forming Foam-Impacted Soil
The environmental fate of per- and polyfluoroalkyl substances (PFAS) in aqueous film-forming foams (AFFFs), especially the PFAS synthesized by electrochemical fluorination (ECF) process, remain largely unknown. In this study, the transformation potential of a variety of ECF-based precursors in a historically used AFFF formulation was evaluated in aerobic soil microcosms. Liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) and mass spectrometry (LC-MS) were employed to identify the precursors in the AFFF formulation and transformation products during the 308-day incubation. Homologues of previously documented degradable precursors and some precursors (e.g., N-carboxy ethyl dimethyl ammonio propyl perfluoroalkane amide) that have unknown biodegradability were found to be transformed. Transformation pathways for sulfonamide- and carboxamide-based precursors were presented. In addition, the chemical structures were found to be important factors impacting the stability of these precursors. These findings provide valuable information regarding the fate and transformation of ECF-based PFAS in contaminated soils.