PFAS OCCURRENCE AND INTERACTION WITH NATURAL MATERIALS IN THE SUBSURFACE

Abstract

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals that have been widely used in industrial and consumer products due to their water- and grease-repellent properties. However, PFAS are persistent in the environment, and their widespread contamination has raised concerns about their potential health and environmental risks. Understanding the occurrence and interaction of PFAS with natural materials in the environment is crucial for assessing their long-term impact on ecosystems and human health. Knowledge of how PFAS transport, accumulate, and interact with minerals, sediments, and groundwater helps inform remediation strategies and guide policy development to mitigate their harmful effects.Understanding the historical occurrence of PFAS is crucial for assessing their extent of contamination, environmental persistence, and fate and transport. Historical samples provide valuable insights into the history of PFAS usage, shedding light on past industrial practices and their long-term impact on the environment. Given their persistence, PFAS interact with natural materials such as soils, aquifer sediments, and colloids, which can influence their transport and adsorption behavior. Analyzing these interactions and adsorption trends helps in understanding how PFAS migrate and accumulate in the environment. Modeling studies are an effective approach to simulate PFAS transport, but to ensure accuracy, these models require high-resolution data for calibration. Therefore, the need for comprehensive and high-resolution datasets is paramount to improve the precision of such models and better predict PFAS behavior in natural systems, facilitating the development of effective remediation strategies. This dissertation (1) analyzed historical PFAS concentrations in aquifer materials in Wisconsin, revealing a steady increase in PFAS contamination over time, (2) determined a high-resolution vertical profile of PFAS in aqueous film-forming foam-impacted soils, suggesting that vadose zone could be a long-term PFAS source, (3) explored PFAS adsorption onto natural colloids and soil in rainwater and groundwater, shedding lights on the influence of colloid-facilitated PFAS transport, and (4) examined the adsorption of perfluoroalkyl acids (PFAAs) by aquifer materials, highlighting the role of dolomite and chemical properties in PFAS adsorption. This study provided valuable insights into the persistence and transport of PFAS in the environment, contributing to the development of effective strategies for remediation and risk management.