Date of Award

2026

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Environmental Engineering (MS)

Administrative Home Department

Department of Civil, Environmental, and Geospatial Engineering

Advisor 1

Noel R. Urban

Committee Member 1

Judith A. Perlinger

Committee Member 2

Carol A. MacLennan

Abstract

This study evaluates changes in dissolved polychlorinated biphenyl (PCB) concentrations in Torch Lake, Michigan, an Area of Concern shaped by decades of legacy contamination and evolving restoration policy. Passive samplers deployed across sites and seasons (2024–2025) show total PCB concentrations ranging from below detection to 110 pg/L (mean = 16.8 pg/L), representing an approximate 90% decline since 2005. Comparisons with regional reference lakes indicate no statistically significant difference (p = 0.84), suggesting concentrations may approach background atmospheric levels despite continued variability. Congener profiles indicate a shift toward lower-chlorinated PCBs, though interpretation of higher-chlorinated congeners is limited by slow sorption kinetics. Despite substantial progress, ongoing sources and ecological lags highlight the long-term nature of remediation. This work provides an updated baseline of PCB concentrations in the water column of Torch Lake although improved sampling approaches are needed to better constrain low-level PCB contamination.

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