A study led by University of Rhode Island Graduate School of Oceanography alumnus Jarod Snook has identified long-term sources of per- and polyfluoroalkyl substances entering the Pawcatuck River from two historically contaminated textile mill waste retention ponds.

Better known as PFAS or forever chemicals, this largely toxic group of manufactured compounds has been used in industry and consumer products since the 1940s. They don’t readily break down and can build up in people, animals, and the environment over time. They can persist for decades and travel long distances, moving from inland rivers like the Pawcatuck River to coastal waters and the Atlantic Ocean.

Published in the scientific journal Environmental Science & Technology Water, the study was co-authored by members of the Lohmann Lab at the Graduate School of Oceanography, including assistant professor Jitka Becanova, marine research associate Simon Vojta, and professor Rainer Lohmann.

Using a combination of environmental sampling techniques and modeling, the team characterized how PFAS stored in pond sediments continue to migrate into, and be deposited within, the river decades after textile operations ceased.

In fact, one of the study’s key findings is that sediment at one of the ponds could continue releasing PFAS into the Pawcatuck River for more than 100 years, highlighting the long-term nature of the contamination and a problem that will persist unless steps are taken to remediate.

When forever chemicals enter a river, they can contaminate water and sediments, accumulate in aquatic organisms, disrupt local ecosystems, and pose risks to humans and wildlife through drinking water and seafood consumption.

The Pawcatuck River is widely used for recreation and fishing, creating potential exposure pathways for humans and raising concerns about long-term public health impacts.

“Rhode Islanders value their aquatic environment,” Snook said. “Keeping it free from pollution is part of that value. We hope this study sheds light on the PFAS issue affecting the Pawcatuck River so that action can be taken to remediate contamination at its source.”

The two mill sites were previously identified by the Lohmann Lab as PFAS “hot spots,” where concentrations in the Pawcatuck River increased sharply downstream of the retention ponds. Those findings prompted a closer investigation into how much contamination remained in the sediments and how long it might continue affecting the river.

Central to the study was a passive sampling device designed by Snook during his doctoral research at the Graduate School of Oceanography, while he concurrently served as a trainee in URI’s STEEP (Sources, Transport, Exposure & Effects of PFAS) Program. The device allowed researchers to measure PFAS in the water and calculate the movement from contaminated sediments into surrounding waters over time.

By studying these well-defined and accessible freshwater sites, the team aimed to better understand local contamination and demonstrate a transferable approach to PFAS site characterization. With clear boundaries and well-documented histories, the sites serve as valuable case studies for PFAS-contaminated freshwater systems elsewhere in the United States and globally.

Decisions about environmental remediation depend on multiple factors, but they are grounded in an understanding of both the magnitude and persistence of contamination, according to Snook. With that in mind, the research team prioritized producing actionable, scientifically grounded insights for regulators.

“We wanted regulators to have a foundation to start planning effective solutions,” Snook said. He noted additional data on contamination depth, concentration, and transport pathways could further inform future remediation planning.

As concerns about PFAS contamination grow, this research provides a detailed case study in how persistent contaminants can continue to impact freshwater systems over decades.