Clarkson University
Institute for a Sustainable Environment
Ogechukwu Ofodum
Environmental Science and Engineering MS Candidate
Wednesday, April 23, 2025
11:00 AM
ABSTRACT
The Great Lakes are a group of five interconnected freshwater bodies in North America. These lakes are ecologically diverse, supporting numerous plant and animal species, and they play a vital role in transportation, industry, and tourism. Factors such as pollution from industrial and agricultural activities have long affected the health of the Great Lakes ecosystem, leading to the establishment of the U.S. EPA Great Lakes Fish Monitoring and Surveillance Program (GLFMSP). This program monitors contaminant levels in lakes, including per- and polyfluoroalkyl substances (PFAS). PFAS are a group of synthetic chemicals widely used in industrial and consumer products since the 1940s due to their unique stability, resistance, and surface tension-lowering properties. However, the widespread presence of PFAS in the environment raises concerns about their persistence, bioaccumulative nature, and potential adverse effects on human and ecosystem health, particularly in aquatic ecosystems.
The current study investigates the long-term (~18 years) trend of 15 individual PFAS including C4-C14 perfluoroalkyl carboxylic acids (PFCA) and C4-C10 perfluoroalkyl sulfonic acids (PFSA) and total PFAS, in lake trout (Salvelinus namaycush) and walleye (Sander vitreus; Lake Erie only) collected annually from 2005 to 2022 from the five Laurentian Great Lakes. A statistically significant decline in total PFAS concentrations across the basin was observed, with the steepest decreases occurring in Lake Ontario (Thiel-Sen’s slope = –1.12 ng/g/year, p < 0.005) and Lake Erie (–1.07 ng/g/year, p < 0.005). Lake Superior exhibited a modest, yet significant, trend (–0.046 ng/g/year, p = 0.016), consistent with its fewer contamination sources and remote region. However, an increasing concentration of PFCA when comparing 2005 and 2021 at the Port Austin and Keweenaw point sites, respectively was observed.
Investigating individual analytes per lake, a gradual trend decline was observed in C8 PFCA (p > 0.05) and C6 PFSA (p < 0.05) in all the lakes while C9 PFCA (p <0.05) was found to be increasing in Lake Superior. PFOS remained the dominant analyte detected throughout the basin. Variations in concentration trend across lakes seem to be influenced by past contamination sources, hydrological factors, and bioaccumulation potential.
While declines demonstrate the success of regulatory measures, source management and voluntary phase out, the persistent presence of PFAS in aquatic organisms emphasizes the need for ongoing monitoring. This monitoring should also evaluate alternative replacement for legacy PFAS and their toxicological impacts.