God'sgift Nkechi (Gift) Chukwuonye
Graduate Student, PhD
Mentor:
Dr. Monica Ramirez-Andreotta
Department:
Environmental Science
Abstract:
Per- and polyfluoroalkyl substances (PFAS) are pervasive environmental pollutants with significant impacts on ecosystems and public health. This study aimed to characterize PFAS concentrations in a community impacted by active and legacy copper mining, compounded by wildfires and flash floods. Additionally, the study explored the (re)mobilization of PFAS and co-occurrence with metal(loid)s following these events. Twenty-eight PFAS compounds in 35 residential and 8 control surface soil samples were analyzed via liquid chromatography-tandem mass spectrometry. The maximum total PFAS concentration observed in the residential samples was 96.40 µgkg-1, compared to 1.69 µgkg-1 in the control samples. Perfluorobutanoic acid (PFBA) had a maximum concentration of 61 µg kg-1 in residential samples, while Perfluorohexane sulfonic acid (PFHxS) had the highest concentration in the control samples at 0.92 µg kg-1. Long-chain PFAS were most dominant in this study. Perfluorooctane sulfonic acid (PFOS) (58% of the samples), Perfluorooctanoic acid (PFOA (35%), and Perfluorohexane sulfonic acid (PFHxS) (72%) exceeded the U.S. EPA Soil-to-Groundwater Risk-Based Screening Levels, highlighting the potential risk of contaminants migrating from soil to groundwater, which could ultimately impact groundwater quality. Co-occurrence analysis revealed that increases in PFAS concentrations were positively associated with Zn (β = 1.25, p = 0.0034) and Ba (β = 1.23, p = 0.0284) but negatively associated with Pb (β = -0.83, p = 0.0115) and Co (β = -1.38, p = 0.04671). In general, a spatial distribution map indicated that greater PFAS concentrations were observed near potential sources i.e., active mines. This evidence combined with select metal co-occurrence highlights mining’s potential role in PFAS contamination risks and environmental impacts.
