Date of Award

Spring 2025

Project Type

Thesis

Program or Major

Natural Resources

Degree Name

Master of Science

First Advisor

Adam Wymore

Second Advisor

Paula Mouser

Third Advisor

Wilfred Wollheim

Abstract

Per- and polyfluoroalkyl substances (PFAS) are persistent man-made chemicals that accumulate in aquatic environments due to their widespread industrial and commercial use and resistance to degradation. Understanding their spatial distribution and relative abundance in streams draining suburbanizing watersheds is crucial for effective watershed and water quality management. This study investigates how the concentrations and composition of PFAS in surface water and sediment are impacted by urbanization. PFAS were quantified in the Lamprey River watershed, a coastal watershed in southeastern New Hampshire that is experiencing ongoing suburbanization. Sampling sites include tributaries, mainstem, and estuarine areas. Surface water, sediment, and well water samples were collected once in Fall of 2023 and once in Spring, Summer and Fall of 2024. Concentration of 40 PFAS compounds were quantified using EPA Method 1633 in a commercial laboratory. This study assessed multiple water quality parameters including major cations and anions, total dissolved nitrogen (TDN), and dissolved organic C (DOC), to investigate the relationship between PFAS and surface water chemistry. Results indicate significant spatial and temporal variation in PFAS concentrations. A significant positive relationship between total PFAS and chloride was found, but chloride was found to be a poor proxy for urbanization in the Lamprey River watershed. Seasonal patterns revealed peak PFAS concentrations in surface water in July and September 2024. The PFAS chloride relationship likely points towards potential groundwater inputs of PFAS. A Principal Component Analysis (PCA) identified PFHxA, PFOA, and PFHpA as the compounds driving variation between sites but 4:2FTS and HFPO-DA driving varioton between sample mediums (surface water, well water, sediment, and atmospheric samples). Estuary sites saw higher number of total compounds detected in sediment than in freshwater. Overall, these findings have implications for future monitoring and management efforts aimed at mitigating the impact of these contaminants in suburbanizing watersheds

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