Airborne microplastics and PFAS: Distribution and interactions in the urban atmosphere

Microplastics (MPs) and per- and polyfluoroalkyl substances (PFAS) are persistent emerging contaminants of global concern due to their environmental persistence, mobility, and potential health risks. While their occurrence in aquatic and terrestrial environments has been widely studied, their presence, distribution, and interactions in the urban atmosphere remain poorly understood. This dissertation investigates the occurrence, characteristics, and interactions of airborne MPs and PFAS in northern New Jersey. It is hypothesized that airborne MPs can act as carriers for PFAS and that atmospheric aging processes enhance their adsorption capacity.Field sampling and laboratory analyses were conducted to characterize airborne MPs and PFAS across multiple environmental matrices, including indoor and outdoor air, particulate matter, wet deposition, and total deposition. Microplastic abundance, morphology, and polymer composition were determined, while PFAS concentrations and phase partitioning between gas and particulate phases were quantified. Laboratory experiments simulated atmospheric aging through cyclic temperature fluctuations (-20 °C to 45 °C) to evaluate changes in MP surface properties and their effects on PFAS adsorption.Results indicate that airborne MPs are widespread in both indoor and outdoor environments, with indoor deposition rates substantially higher than outdoor rates. Outdoor deposition rates were only 2-8% of indoor rates, highlighting indoor environments as a potentially important source of human exposure. Dominant polymer types included polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), and polypropylene (PP). Airborne PFAS were detected in both gas and particulate phases, with the gas phase dominating atmospheric concentrations. The average gas-phase PFAS concentration was 197.7 ± 47.9 pg·m-3, approximately four times higher than the particle-phase concentration of 48.3 ± 47.9 pg·m-3, highlighting the importance of the gas phase in PFAS atmospheric transport. Laboratory aging experiments demonstrated that cyclic temperature fluctuations induced surface oxidation and microscale defects on PE microplastics, increasing PFAS adsorption on larger MPs by approximately 30-50%, particularly for mid- and long-chain PFAS.Overall, this dissertation provides a comprehensive assessment of airborne MPs and PFAS in an urban atmosphere. The results demonstrate that thermally aged microplastics can enhance PFAS adsorption and atmospheric transport, revealing an important pathway influencing the environmental fate and exposure risks of these contaminants.