Year Established: 2011 Start Date: 2011-06-01 End Date: 2012-05-31
Total Federal Funds: $27,500 Total Non-Federal Funds: $36,360
Principal Investigators: Nathan Johnson
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 downsteream 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.