Per- and Polyfluoroalkyl Substances (PFAS) in Air, Water, and Soil and Their Impact on Air Quality
Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals of growing environmental and public health concern due to their persistence and toxicity. This study focuses on fluorotelomer alcohols (FTOHs) and fluorotelomer acrylates (FTAcrs), key volatile PFAS classes, for which ambient air data is limited despite advances in method development for indoor air and consumer products. A unified analytical method was developed using a single GC-MS instrument equipped with both liquid sampling and thermal desorption, minimizing uncertainty and ensuring high recovery. Instrument detection limits were 0.02–0.06 ng/tube for FTOHs and 0.02–0.08 ng/tube for FTAcrs. Stability tests over seven days showed minimal analyte loss, with relative standard deviations (RSDs) of 2.13–3.95% for FTOHs and 2.23–3.34% for FTAcrs in spiked thermal desorption tubes. RSDs for polypropylene vial storage were 1.31–3.91% and 2.01–3.84%, respectively. Breakthrough was negligible (<2% in backup tubes at 20 L carrier gas). Applied to urban air, the method revealed temperature as the primary driver of gas-particle partitioning, with the 6:2/8:2 ratio decreasing from 3.43 to 1.65 as temperature dropped from 24.1°C to 10.7°C. Chain-length-dependent partitioning was observed, with 6:2 compounds remaining in the gas phase (1.96–2.20 ng/m³) and 10:2 congeners shifting to particles (gas-to-particle ratios as low as 1.7), indicating that shorter-chain fluorotelomers predominantly undergo long-range gas-phase transport. Chapter 2, analyzing Houston Bayou water and precipitation (Dec 2025–Mar 2026), found PFCAs dominated both matrices, with short-chain homologues in rainwater (79%) and near-equal distribution in bayou water (47%). Correlation analysis showed chain-length-driven partitioning, except for the PFOA-PFBA anomaly (r=0.859), suggesting a common local source. PMF identified six sources in precipitation and five in water, with AFFF and food packaging as major contributors. Chapter 3 revealed distinct PFAS signatures in soil and rainfall, with soils dominated by long-chain PFCAs (C10–C12, 98% of ΣPFCAs) and PFDoA as the primary congener, while rainwater showed short-chain PFCA dominance (79%). PMF attributed 35% of soil PFAS to electroplating, 35% to plastic emulsification, and 8% to AFFF. These findings suggest that soils act as long-term reservoirs for hydrophobic PFAS, while rainfall transports volatile, short-chain homologues.
Gas-particle phase, PFAS, Phase distribution, Air, Water, Method development, Soil
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