Seminar

Abstract

Here we will explore two stories of how chemicals move through the atmosphere: PFAS and pesticides. Per- and polyfluoroalkyl substances (PFAS) are long-lived environmental contaminants of concern for human health. When released into the atmosphere, they can undergo long-range transport, followed by return to Earth through deposition. We have quantified 15 PFAS in rainwater from the central United States. During summer 2019, PFAS concentrations ranged from 50-850 ng/L, as measured by liquid chromatography tandem mass spectrometry. Trifluoroacetic acid accounted for approximately 90% of all PFAS. Levels of perfluorooctanoic acid (PFOA) and perfluorosulfonic acid (PFOS) were comparable to levels observed over the past two decades in spite of regulatory restrictions. We also detected HFPO-DA (GenX), a replacement for legacy PFAS, at all measurement sites. Analysis by ANOVA modeling and correlation matrices indicated statistically significant differences (p < 0.05) in PFAS profiles at sites separated by tens to hundreds of kilometers, highlighting the importance of local point sources on deposition of PFAS in the United States. In our more recent work, we have expanded our precipitation analysis to characterize pesticides in precipitation samples using suspect screening with high-resolution mass spectrometry and air mass back trajectory analysis.

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Dr. Jennifer Faust (she/her/hers) joined the faculty at the College of Wooster in fall 2017 as an assistant professor of analytical and environmental chemistry. She previously obtained her PhD in physical chemistry from the University of Wisconsin-Madison in 2015, and she completed a postdoctoral fellowship in atmospheric chemistry at the University of Toronto. Jennifer now leads an undergraduate research group in environmental chemistry at the College of Wooster, where she has mentored one postdoctoral fellow and 29 undergraduate researchers, including 16 senior thesis students. She received a National Science Foundation CAREER award in 2021 to characterize the transport and fate of pesticides in the atmosphere. Other research projects in the Faust group include the formation of brown carbon, the oxidation of rubber, and the occurrence of PFAS in rainwater.