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Subsurface Transport from PFAS Source Zones: An overview of processes and summary of experimental and numerical modeling investigations
Citation:
Brooks, M. Subsurface Transport from PFAS Source Zones: An overview of processes and summary of experimental and numerical modeling investigations. University of Cincinnati seminar, Cincinnati, OH, April 21, 2023.
Impact/Purpose:
An overview of atypical transport processes that may result from high-concentration releases of per- and polyfluoroalkyl substances will be summarized and discussed at a seminar to be given at the University of Cincinnati. Research work being conducted to develop numerical models and validate them using experiments from two-dimensional physical aquifer models will also be presented.
Description:
A distinguishing feature between typical groundwater organic contaminants and per- and polyfluoroalkyl substances (PFASs) of immediate concern is that the latter are fluorocarbon surfactants. Surfactant properties result in several subsurface transport processes that may be considered atypical relative to historic groundwater organic contaminants. For example, surfactant partitioning at fluid/fluid interfaces may contribute to contaminant retardation when immiscible fluids are present (such as air and water in the vadose zone), surfactants may impact subsurface fluid distributions, or they may enhance transport of other contaminants through micelles or emulsions. Impacts to fluids distributions and enhanced transport of co-contaminants may, however, be limited to high-concentration PFAS source zones, and may not be an issue at all PFAS impacted sites. An overview of these processes will be summarized and discussed. Numerical models of subsurface transport are valuable tools for risk assessment and contaminated site management. Traditional groundwater models, however, do not include atypical subsurface PFAS transport processes. New models have been proposed and are under development. However, testing and validation of these models has predominately been accomplished using one-dimensional laboratory column tests, and there is a need for more rigorous validation exercises. Experiments in bench-scale, two-dimensional physical aquifer models provide data sets that represent an immediate level of complexity between that associated with one-dimensional column experiments and real-world sites. Research work being conducted to develop numerical models and validate them using experiments from two-dimensional physical aquifer models will also be presented.