Poly and perfluoroalkyl substances (PFAS) are man-made chemicals. PFAS have been used in a variety of products due to their stability and other valuable chemical properties. However, PFAS this stability also makes PFAS difficult to biodegrade in the environment. In addition, their properties also pose a threat to human health and the environment. It is estimated that over six million Americans have been exposed to PFAS in the water supply, and PFAS is considered one of the most important issues in environmental contamination facing the Nation. This concern results from studies that have shown that some PFAS can enter and remain in the human body, potentially causing cancer and other health problems. This knowledge has led to many efforts to treat water sources to remove PFAS when discovered. Pumping and treatment of groundwater is one of these commonly used treatment approaches. While this approach has worked for some pollutants, the PFAS movement in groundwater is difficult to predict because we do not fully understand the interactions between PFAS and natural organic matter (NOM) present in soil. The goal of this CAREER project is to address this knowledge gap by investigating the interactions of NOM and PFAS. This will be achieved through a series of experiments with well characterized model systems. Understanding this process will allow us to improve groundwater treatment systems to protect human health. This work will be used to educate the public through outreach to increase awareness of PFAS challenges and efforts to address these concerns. These efforts will increase the scientific literacy of the Nation while educating the public on important health issues.
The goal of this CAREER proposal is to identify the mechanisms of PFAS interactions with organic matter in soils. This will be achieved using a range of conventional and novel analytical approaches to assess how organic matter, cations, and PFAS interact through a framework including solution phase complexation and accumulation at air-water and solid-water interfaces. Mechanistic insights gained from this research could explain previously observed variability in sorption distributions and rate constant values. The proposed work will combine batch, static column, and flow-through column experiments to assess PFAS transport from a near surface sources through the vadose zone and saturated groundwater. An idealized porous media system will be created using polymer-coated beads, where the polymers will be employed as homogeneous well-defined soil organic matter proxies. Mechanistic insights will be enabled through the use of organic matter proxies to elucidate how chemical moieties affect PFAS-organic matter interactions. PFAS complexation by dissolved organic matter and cation binding constants will be determined based on co-elution in size exclusion chromatography. Air-water interfacial accumulation will be evaluated using droplet contact angle coupled with stacked multi-ring static columns operated in drainage and secondary imbibition modes. Finally, PFAS transport in flow-through columns will be completed using continuous effluent analysis by high resolution mass spectrometry to quantify PFAS concentrations in the column effluent. The project includes a multi-component outreach effort: 1) educational activities will focus on outreach to middle and high school students, 2) research opportunities for undergraduate students from a range of disciplines, and 3) development of multi-disciplinary thinking in graduate students. These efforts will benefit the Nation through increased scientific literacy and enhancement of the Nation’s STEM workforce.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
