No simple solution to Great Lakes mercury pollution problem

Nearly 80 percent of Michigan’s Upper Peninsula is affected by toxic mercury, leading to continued fish advisories in and around the Great Lakes. Researchers at Michigan Technological University are now investigating what must be done to make the fish safe for consumption.

Mercury is a widespread pollutant and its regulations vary worldwide. For the the Keweenaw Bay Indian Community (KBIC), the question has become: when is it safe to eat the fish? In order to answer this question, an interdisciplinary study was developed among biogeochemical modelers, environmental engineers, and social scientists.

Mercury is an atmosphere-surface exchangeable pollutant (ASEP). These molecules are invisible, tasteless, and they can move over great distances. ASEP molecules travel through the air, landscape, water, and animals.

Study lead researcher Judith Perlinger is a professor of Environmental Engineering at Michigan Tech.

“We’re taking phenomena that act on a global scale and predicting what they will do,” said Perlinger. She added that working with the KBIC was critical to the project. “Clearly the issue matters to them, so how can we make the science relevant to them?”

The research team focused on mercury and three different policy scenarios through the year 2050. In the first scenario, mercury emissions from human activities were completely eliminated. In the second, more moderate policy action was taken, and no policy action was implemented in the third scenario.

The study revealed that there would be little change within the lifetimes of the KBIC community regardless of the scenario. Study co-author Noel Urban explained that the process would likely take generations to reach levels that the community considers safe.

“People assume that what is deposited in a forest is also deposited the same in a lake, which isn’t true, so models have been miscalculating,” said Urban. “This is apparent in the Great Lakes, and the Upper Peninsula is a particularly sensitive landscape to mercury.”

The analysis of mercury concentration in the lakes combined with estimates of mercury in fish from similar water bodies revealed that mercury persists differently depending on the size of the lake.

“Which poison do you want?” said Urban. “Go to the big lakes and get PCBs, go to the small lakes and get mercury.”

While admitting that there is no simple answer to the KBIC’s question, the team will continue to assess the regional impacts of mercury in the Great Lakes. The current study will be published in the journal journal Environmental Science.

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By Chrissy Sexton, Earth.com Staff Writer