State Water Resources Research Institute Program

Project ID: 2011MN290B
Title: The role of sulfate reduction in sediment of the St. Louis River estuary: Phase II
Project Type: Research
Start Date: 6/01/2011
End Date: 5/31/2012
Congressional District: MN 8th
Focus Categories: Sediments, Toxic Substances, Geochemical Processes
Keywords: sediment, sulfate reduction, mercury, biogeochemistry
Principal Investigator: Johnson, Nathan (University of Minnesota Duluth)
Federal Funds: $ 27,500
Non-Federal Matching Funds: $ 36,360
Abstract: Proposals to begin non-ferrous mining on the Mesabi iron range in the upper reaches of the St. Louis River watershed have drawn attention due to a variety of environmental concerns including the potential mobilization of sulfate. The transformation of mercury to the toxic methyl mercury form is known to be integrally tied to sulfate reduction in many environments. Although substantial contributions of sulfate from mining influenced tributaries has been observed, relatively little is known about the role sulfate plays in mercury-related processes downstream in the downstream St. Louis River Estuary, a popular sport fishing destination with restrictions on fish consumption due to mercury. The objective of the proposed project is to determine whether sulfate is the limiting factor in the production of methyl mercury in the sediments of the St. Louis River estuary. Both physical and mathematical modeling of the biogeochemical processes influencing mercury in sediments will be employed. The results will help to determine the influence of increased sulfate loads on methyl mercury production and consequent accumulation in fish tissue in the St. Louis River Harbor.

Progress/Completion Report, 2011, PDF

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