Concerns regarding per- and polyfluoroalkyl substances (PFAS) in the environment have grown dramatically in recent years. Large quantities of aqueous film-forming foam (AFFF) products containing PFAS have been used for firefighter training activities and in response to fire emergencies. Significant concentrations of PFAS have been found in shallow soils associated with past AFFF use, and these soils may serve as long term sources to groundwater. The primary objective of this project is to demonstrate phytoremediation approaches for managing shallow soils impacted by PFAS to significantly reduce source loading to groundwater. The benefit of phytoremediation approaches for extracting PFAS (i.e., phytoextraction) from soils at low cost will also be demonstrated. In addition to demonstrating phytoremediation approaches for reducing downward migration through unsaturated vadose zone soils, this project also will investigate uptake of PFAS by representative wetland plant species.
Phytoremediation uses plant biology to address risks associated with environmental pollutants, and encompasses a variety of different processes. This project focuses primarily on the use of plants to provide vegetative cover to alter the water balance between precipitation and drainage, thus limiting the downward migration of PFAS, as well as through phytoextraction and phytostabilization (i.e., stabilization of PFAS in the vicinity of plants). Phytoremediation effectiveness will be assessed in fully instrumented field plots to measure drainage and PFAS concentrations. Water balance and PFAS flux will be compared between plots containing plant and amendment treatments, as well as non-vegetated control plots. PFAS extracted into plants also will be measured.
The primary benefit resulting from this work will be the demonstration of phytoremediation as a sustainable and cost-effective approach for reducing PFAS loading to groundwater. Phytoremediation may be significantly cheaper than conventional excavation or capping approaches. Additionally, phytoextraction may provide a suitable alternative approach for removing PFAS from shallow soils in a cost-effective manner. Finally, well designed phytoremediation sites can be aesthetically pleasing and provide other ecological benefits, such as improved wildlife habitat and reduced erosion.