Abstract: Perfluoroalkyl acids (PFAAs) have been recently highlighted in the news due to their presence in groundwater and drinking water resources, as well as concerns that they are persistent, bioaccumulative, and toxic. Aqueous film forming foams (AFFF) have been used at firefighter training areas to extinguish liquid fuel fires and the repeated historic use of AFFF is associated with elevated perfluoroalkyl acid (PFAAs) concentrations in the subsurface. In this work, the fate and transport of PFAAs in the subsurface is investigated to determine the water quality, co-contaminants, and chemical oxidants affect the PFAAs fate and transport through the saturated porous media system. Unfortunately, chemical oxidants did not degrade the PFAAs, but water quality had substantial effects of the PFAA mobility. The presence of a tricholoroethylene (TCE), a nonaqueous phase liquid (NAPL), slowed PFAA transport, as did depressed pH values and elevated cation concentrations. By contrast, chemical oxidant application had mixed effects: two chemical oxidants (permanganate and catalyzed hydrogen peroxide) resulted in accelerated PFAA transport which was attributed to both geochemical and water quality changes, while persulfate application resulted in increased PFAA retardation (i.e., decreased mobility), which is likely at least in part due to changes in water quality. Monte Carlo simulations were employed to extend these results to understand the implications of environmentally relevant water quality parameters on PFAA transport in the subsurface.
Biography: Dr. Erica McKenzie grew up in the mountains of Montana, which inspired her interest in environmental pollution. She completed B.S. at Colorado State University (Environmental Engineering, German), and then conducted her graduate studies at University of California at Davis working with Dr. T. M. Young, where she focused on nonpoint source pollutions and metal fate and transport in stormwater runoff and surface waters. As a graduate student, Dr. McKenzie was involved in Engineers Without Borders, where the activities included two project trips to Uganda as well as research efforts to understand point of use drinking water treatment performance. As a postdoctoral scholar at Colorado School of Mines working with Dr. C. P. Higgins, Dr. McKenzie researched perfluoroalkyl substances fate and transport in the subsurface. In 2015, Dr. McKenzie joined the Department of Civil and Environmental Engineering at Temple University in Philadelphia, PA and her research group focuses on environmental chemistry questions evaluated through laboratory experiments and field sampling.