Date of Award
2025
Degree Type
Dissertation
Degree Name
Doctor of Philosophy in Oceanography
Department
Oceanography
First Advisor
Rainer Lohmann
Abstract
Per- and polyfluoroalkyl substances (PFAS) have gained much attention over the last several years in environmental science and engineering communities. They pose a unique challenge: persistent and toxic like several other legacy pollutants, but with additional surfactant and amphiphilic properties increasing the complexity of chemical interactions. Thus, many scientific questions remain regarding the environmental transport, fate, and interactions of PFAS released into natural waters. The dissertation research presented here has focused on several of these questions and knowledge gaps in a vast range of scales - from molecular interactions to global transport of PFAS - all addressing the challenge of PFAS contamination in natural waters. Initial research took place exclusively in the laboratory where PFAS/sorbent interactions were investigated, and a series of recommendations for conducting robust batch-experiments were published for other researchers. Batch experiment parameters such as sorbent/water ratio, initial PFAS concentration, and allowable methanol solution content were examined to determine thresholds within which sorbent/water PFAS partitioning values were valid. This optimized experimental set-up was used to determine true sorbent/water partitioning values to two sorbents for a suite of PFAS.
To provide a new method for measuring PFAS in natural waters, a passive sampler design was adapted, constructed, and validated (in the laboratory and the field) for PFAS. The sampler and its construction materials were tested for uptake, diffusion rates, and challenged to measure accurate PFAS concentrations in water. Several environmental variables were also tested for their effect on uptake. This project resulted in a diffusive gradient in thin film (DGT) passive sampler which can accurately measure dissolved water concentrations of any PFAS with a known structure and helped address analytical and cost challenges of PFAS measurement in water.
The passive sampler, along with sediment coring and laboratory sediment-water partitioning experiments were then used to fully characterize the long-term potential for textile mill retention pond contamination to a river in Rhode Island. The retention ponds, where PFAS chemical waste was discharged, were fully characterized in the aqueous and sediment phases to provide a complete picture of the sites’ potentials to contaminate the Pawcatuck River. Additionally, a modification to the DGT sampler was tested (addition of performance reference compounds) to determine whether it improved DGT water concentration measurements.
Finally, utilizing research cruises as well as international collaborations, water grab-samples were obtained from coastal and remote ocean sites in the North and Equatorial Atlantic and Equatorial Pacific Oceans to test for PFAS, including surface and deep water at each. After characterization of PFAS content, the sources and transport of PFAS to and from these sites was assessed. PFAS was found in North Atlantic Deep Water and Antarctic Bottom Water in the southern hemisphere, and HFPO-DA (a replacement PFAS) was found in significant concentrations in several sampling sites.
The research investigations presented here have combined to provide a better understanding of PFAS behavior, improved measurement of PFAS, and valuable characterization of PFAS contamination in a wide variety of natural waters at local and global scales.
Recommended Citation
Snook, Jarod, "ADVANCING SAMPLING AND EXPANDING MEASUREMENT OF PER- AND POLYFLUOROALKYL SUBSTANCES IN NATURAL WATERS." (2025). Open Access Dissertations. Paper 4487.
https://digitalcommons.uri.edu/oa_diss/4487