Isabella Mei
Research Mentor(s): Katherine Manz
Mentor Department: Department of Environmental Health Sciences
Authors: Isabella Mei, Yiting Xiao, Katherine Manz
Session: Session 4 (1:00pm – 1:50pm)
Presentation Type: Poster 7
Abstract
Historical releases of aqueous film-forming foams (AFFF) introduced per- and polyfluoroalkyl substances (PFAS) into subsurface environments. PFAS is composed of two components: non-polymers and polymers. Within the class of non polymers, two subclasses are introduced: Perfluoroalkyl substances and Polyfluoroalkyl substances. PFAS precursors are considered Polyfluoroalkyl substances, but over time they can be transformed into perfluoroalkyl substances in the environment. The distinction between poly and per simply means unfully fluorinated substance and fully fluorinated substance. The transformation of the PFAS precursor into Perfluoralkyl substances makes the substance much harder to break down and some may become more toxic than the precursor itself. The aim of our study is to investigate how the iron sources, organic matter in soil or groundwater has an impact in the transformation of precursors. To address these challenges, our study introduces a combined method of liquid chromatography and high resolution mass spectrometry (LC/HRMS; Orbitrap 240) to test precursor solutions. This study investigated radical-mediated transformation of PFAS precursors under oxygenation conditions in which we used an inflatable glove chamber/bag to ensure that the experiments conducted with PFAS and Fe(II)-rich minerals (e.g., pyrite and iron (II) sulfide) and dissolved organic matter (DOM) were being manipulated in a controlled environment. To prevent unwanted chemical reactions, we used nitrogen to remove oxygen and moisture. PFAS precursors exposure to oxygen would allow the iron solutions to generate hydroxyl and hydrogen radicals despite the persistent free radicals within DOM enhancing the formation of reactive species. Through these findings it can be concluded that the persistent free radicals within DOM and iron-bearing minerals contribute to PFAS precursor transformations in subsurface environments.
