Mercury research and reduction initiative

Many of Minnesota's lakes already have too much mercury contamination. The Minnesota Department of Health (MDH) has issued fish consumption advisories for fish from lakes where the fish have been tested and found to be contaminated with too much mercury.

The Minnesota Pollution Control Agency, Minnesota Department of Natural Resources, the Science Museum of Minnesota, and others have been studying the problem of mercury in Minnesota's lakes too. This environmental research will help the state find ways to prevent mercury contamination.

By taking core samples of lake sediments and analyzing them for mercury, MPCA and Science Museum scientists can estimate where the mercury came from and begin tracking trends in mercury contamination.

A recent study indicates that less mercury is getting into Minnesota lake sediments than in the past, while studies in Alaska show that mercury from global sources is continuing to rise. If this increase in global mercury continues without corresponding local and regional decreases, mercury contamination in Minnesota fish will also rise.

diagram of mercury accumulation rates in sediment cores

Wetlands are a major site where inorganic mercury deposited from the atmosphere is converted to methylmercury, the bioaccumulative form of mercury that leads to fish consumption advisories. An MPCA study conducted with a U.S. Environmental Protection Agency grant addressed the question, "How do constructed stormwater wetlands compare to natural wetlands in the production of methylmercury, given the important differences in hydrologic and pollutant loads?"  The study collected water chemistry data from 10 urban stormwater wetlands, nine of which are designed to treat stormwater before entering a lake. The study results showed a strong relationship between phosphorus concentrations and methylmercury concentrations in stormwater wetlands. It also found that stormwater wetlands are very similar to natural wetlands in methylmercury levels.

Minnesota's mercury initiative

State and federal mercury laws have been effective, but we must do more. The MPCA has studied its options, with the help of a grant from the U.S. Environmental Protection Agency and the assistance of a group of other interested people. This Advisory Council studied the issues and made recommendations in 1998.

The MPCA's goals for the Mercury Contamination Reduction Initiative:

  • significantly reduce mercury contamination,
  • use cost-effective methods, and
  • work in cooperation with everyone who has an interest in the results.