Date of Award

2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Oceanography

Specialization

Chemical Oceanography

Department

Oceanography

First Advisor

Rainer Lohmann

Abstract

Per- and polyfluoroalkyl substances (PFAS), also referred to as “forever chemicals”, are classified as a group of emerging persistent organic pollutants due to their environmental ubiquity, persistence, and toxicity to life. They have a unique chemistry that gives them stain-resistant and waterproof properties, making them desirable for use in many industrial and consumer products. However, this same chemistry also makes them extremely resistant to biological and environmental degradation. Large data gaps remain surrounding the distribution, transport, and impacts of these contaminants, particularly in the atmosphere. The work in this dissertation focuses on closing some of these knowledge gaps and provides tools and insights to support future research on PFAS in the environment.

A main roadblock in improving our understanding of PFAS in the environment is the lack of widely accepted tools that are reliable and easy to use. For the atmosphere specifically, currently existing tools are impractical for large scale deployments or unsuitable for capturing the full scope of PFAS present. To address this, a novel passive sampler was developed, combining a radial diffusive tube with a high-capacity sorbent to measure both volatile and ionic PFAS in the atmosphere. Calibration was performed both empirically, through simultaneous active and passive sampling in a controlled environment, and theoretically, using a model based on the diffusive path of a compound. Sampling rates determined in calibration were shown to be dependent both on temperature and wind speed. Performance of the passive sampler was validated through “challenge” deployments where the actual atmospheric PFAS concentration was known. The passive sampler was then deployed in contrasting indoor environments in different regions, where concentrations were shown to be dominated by 6:2 fluorotelomer alcohol (6:2 FTOH)- a neutral, volatile compound. Overall, this work demonstrated the passive sampler as a promising tool for measuring a wide scope of atmospheric PFAS in various environments.

The passive sampler was then utilized in a large-scale outdoor campaign to measure atmospheric PFAS across the state of Michigan and improve our understanding of their distribution in the environment. Deployment of passive samplers at 27 sites provided insight into preferential transport of atmospheric PFAS. For example, perfluorooctane sulfonic acid (PFOS) was predominantly detected in the gas-phase, whereas perfluorobutanoic acid (PFBA) was largely detected in the particulate-phase. 6:2 FTOH was frequently detected, as observed in indoor environments, and had a significant positive correlation with both population density and industry density.

In an indoor environment, atmospheric PFAS concentrations are of significant concern due to inhalation of air being an exposure pathway for humans. To assess the contribution of air inhalation to total exposure, PFAS concentrations in air and dust were measured across 40 homes in the Faroe Islands. Being a remote fishing community, the Faroese diet is also a concern for exposure as elevated concentrations of PFAS have been measured in their marine foods, including pilot whale. Exposure from indoor matrices was found to not be a significant contribution for those who consume marine foods enriched in PFAS. Regardless, the findings from this research highlighted the importance of understanding indoor exposure- especially for communities where contaminated diet is of less of a concern- and provides information for best practice on mitigating PFAS exposure.

Finally, the novel passive sampler was used in a regionwide campaign to measure spatial and seasonal patterns of atmospheric PFAS and investigate the impact on surface water contamination. Water and air samples were collected monthly over a year-long period at 6 sites in New Jersey and along the Delaware River. Again, 6:2 FTOH was the dominant compound in the atmosphere, with perfluorooctanoic acid (PFOA) being the dominant compound in water samples. Perfluorobutanesulfonic acid (PFBS) was often detected in the gas-phase and as seen in Michigan, PFBA was predominantly detected in the particulate-phase in the atmosphere. Atmospheric concentrations of PFAS were generally higher in areas with higher population density and in the warmer seasons.

Overall, this dissertation research consisted of large-scale deployments in both indoor and outdoor environments that provided valuable insight into the distribution of atmospheric PFAS, their transport, their possible impact on the wider environment, and their implications for human health. Furthermore, a key outcome of this research is the development of a novel tool and improved methods that can help facilitate and advance future research in this field.

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