Dr. Christopher Zahasky - The role of the vadose zone on the fate and timing of PFAS contamination in groundwater systems.

Speaker: Christopher Zahasky

Abstract:

Per and polyfluoroalkyl substances (PFAS) are an emerging group of anthropogenic contaminants found throughout the environment and increasingly in drinking water. The unique properties of PFAS strongly control the transport and timing of PFAS from surface source zones where they enter vadose zone and potentially migrate into groundwater systems. PFAS adsorb to both soil grains and fluid boundaries within porous media with the extent of adsorption being controlled by a range of environmental and geologic conditions. Quantification of PFAS transport in realistic geologic systems is further complicated by processes such as heterogeneous adsorption and preferential flow pathways that create dynamic and complex contaminant transport behavior. In this study, two vadose zone modeling approaches are used to approximate PFAS transport and timing from two potential PFAS source zones down to the water table. The proposed modeling framework highlights the underlying uncertainty contained within the models by presenting the PFAS transport forecast as a probability of exceeding a contamination threshold across space and time. This type of framework is key for stakeholder risk assessment and decision-making in PFAS contaminated aquifers.

Bio:

Dr. Christopher Zahasky is an assistant professor at the University of Wisconsin-Madison in the Department of Geoscience. Prior to coming to the University of Wisconsin-Madison, he was a postdoctoral scholar at Imperial College London and Stanford University. He completed his PhD and MSc degrees in Energy Resources Engineering at Stanford University. He completed his Bachelor of Science degree in Geology at the University of Minnesota. His research interests are focused on understanding the fundamental physics and mechanisms of fluid, colloid, and solute transport in geologic systems across length and time scales using experimental observations validated and generalized with analytical and numerical models.

Host: Charlotte Garing