Human exposure to mercury (Hg), a powerful neurotoxin, occurs primarily from eating Hg-contaminated fish. Although US air emissions of Hg from combustion sources have declined, Hg concentrations in fish have not decreased. This suggests that atmospheric deposition of Hg is not the only driver of fish Hg levels. Recent upward trends in Hg concentrations in fish in lakes of U.S. and Canada coincide with increased export of organic matter from watersheds, evident beginning in the 1990s in monitoring studies. A unique dataset of Hg in wet deposition (1996-2008 and 2014-present) from the UM Biostation will be utilized and coupled to quantification of Hg isotopes in sediment cores from nearby lakes, to determine contributions of direct atmospheric deposition and watershed runoff of Hg to lakes over time. Improved understanding of mechanisms underlying the rate of recovery of Hg-contaminated lakes will provide insight into effectiveness of ongoing management and policy efforts.
Presented at the 13th International Conference on Mercury as a Global Pollutant, Providence, RI.
Understanding mechanisms underlying the rate of recovery of mercury-contaminated lakes in northern Michigan
Presented at the Central Regional Meeting of the American Chemical Society (ACS CERM), Dearborn, MI.