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Abstract
Per- and polyfluoroalkyl substances (PFAS) are a group of anthropogenic pollutants found ubiquitously in surface and drinking water supply. Due to their persistent nature, bioaccumulative potential, and significant adverse health effects, they pose a concern for human and environmental exposure. The first chapter of the dissertation focused on the development and validation of a target analysis method based on a semi-automated solid phase extraction followed by liquid chromatography-mass spectrometry for the determination of legacy and emerging short-chain PFAS at low parts-per-trillion levels, which was applied to surface waters from Biscayne Bay canals and tap waters from different counties in South Florida (N=36). Total PFAS concentrations of up to 242 ng L-1 in tap water and 106 ng L-1 in surface water raised human health and ecological concerns due to the elevated levels. The second chapter of this dissertation expanded the PFAS monitoring study on the occurrence, composition, spatial and seasonal distribution, and potential sources encompassing tap waters from counties on the East coast of South Florida and Central Florida, and surface waters from Tampa Bay. PFAS were detected in all tap water and surface water samples (N=38), with higher concentrations associated with polluted waterways in Biscayne Bay and sites nearby military airbases and airports. The current findings on PFAS contamination levels from diverse aquatic environments provide additional information for the development of more stringent screening levels that are protective of human health and Florida’s environmental resources. The last chapter of this dissertation focused on developing a non-targeted analysis (NTA) approach based on high-resolution mass spectrometry for a more comprehensive characterization of total PFAS, including degradants and transformation products present in environmental samples that were not measured by target analysis. A total of over 500 PFAS were tentatively identified in drinking and surface waters in South Florida. A semi-quantitation method for NTA (qNTA) was also achieved for the estimation of total PFAS concentration in the samples. A full assessment combining both target and non-targeted approaches play a crucial role in the understanding the diversity of PFAS species in environmental samples, which is needed to better evaluate their toxicological and potential impacts.