Date of Award

8-16-2024

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Susan Richardson

Abstract

Per- and polyfluoroalkyl substances (PFAS) are high-profile environmental contaminants, many having long persistence in the environment and widespread presence in humans and wildlife. Following phase-out of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in North America and restrictions in Europe, PFAS replacements are now widely found in the environment. While liquid chromatography (LC)-mass spectrometry (MS) is typically used for measurement, much of the PFAS is missed. To more comprehensively capture organic fluorine, we developed sensitive and robust methods using activated carbon adsorption, solid phase extraction, and combustion ion chromatography (CIC) to measure total organic fluorine (TOF) in industrial wastewaters, river water, and air. In the first study, two extraction techniques, adsorbable organic fluorine (AOF) and extractable organic fluorine (EOF), were optimized and compared using 39 different PFAS, including replacements, such as GenX and perfluorobutanesulfonate. Our AOF method achieves 64-112% and 87% recovery for individual PFAS and PFAS mixtures, respectively, with 0.5 µg/L limit of detection (LOD). Our EOF method achieves 72-99% and 91% recovery for individual PFAS and PFAS mixtures, respectively, with 0.2 µg/L LOD. Substantially higher TOF values were measured in industrial wastewater, river water, and air samples compared to LC-MS/MS, demonstrating how TOF methods provided a more comprehensive measurement of the total PFAS present, capturing known and unknown organic fluorine. The second study uses the optimized EOF method as well as target LC-MS/MS to conduct a statewide survey of TOF and individual PFAS in 40 surface water locations. Thirty-eight of the locations had detectable levels of TOF. Comparison to target LC-MS/MS revealed that high TOF does not correspond to high individual PFAS measured and vice versa.

Similar to the environmental and health concerns raised by PFAS contamination, harmful algal blooms (HABs) present another critical issue, illustrating the broader challenges of water pollution. Frequent and severe occurrences of HABs pose a growing threat to human health. Increasing incidents of HAB-related Do Not Drink/Do Not Boil (DND/DNB) orders due to the detection of microcystins (MCs) in finished waters above guidelines have brought urgent attention to managing MCs in drinking water. In the third study, the degradation of the MC amino acid moiety in MC-LR by UV/Chlorine, chlorination, and UV/hydrogen peroxide was assessed for the formation of disinfection by products (DBPs) using target gas chromatography mass spectrometry (GC-MS), total organic halogen (TOX), and non-target high resolution GC and liquid chromatography (LC)-MS. In total, 11 DBPs were found above detection limits, with concentrations ranging from 0.1 to 4.6 µg/L. Overall, samples that were treated with UV produced slightly lower concentrations of DBPs than samples not treated with UV. No unknown DBPs were identified by GC-MS, but two DBPs were identified by LC-MS. LC-MS results also show that the use of UV does not degrade M=microcystin as well as treatments without UV.

Rights

© 2024, Alexandria Forster

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