A recent study done by researchers from Michigan Technological University suggests that methyl mercury contamination is a concern on both sides of Lake Superior.
Published in the Journal of Great Lakes Research last fall, an article titled “Legacy mercury releases during copper mining near Lake Superior” tackled the presence of residual mercury from mining operations in the 19th and 20th centuries. Professor W. Charles Kerfoot, a biology prof and director of Lake Superior Ecosystem Researcher at Michigan Tech, became curious about the mine tailings buried in waterways around campus. He told Allison Mills of the Michigan Tech News that “we document [mining] was discharging mercury at 1000 times the normal deposition rate in the region.” The research aimed to quantify this deposition, “and it was a real wake up call.”
Kerfoot set out with Noel Urban, professor of civil and environmental engineering and director of Center for Water and Society at MTU, and a team of researchers to collect core samples by boat. The team was looking to quantify how much mercury from the mining operations had turned up in Keweenaw Waterway and Torch Lake, and then to see how much had become methyl mercury over time. The watersheds mentioned are connected to Lake Superior.
Mills explains: “Booms and busts rocked not just the area’s economy, but also heavy metal fluxes. Naturally, some metals – including mercury – make their way into water bodies. Mining speeds up that process, and the more mining, smelting, and processing taking place, then the more heavy metals get deposited.”
While mercury is not toxic in its organic form, methyl mercury can be formed by bacteria, which then enters the food chain. Methyl mercury is the big concern: it can cause a host of health damages to both the ecosystem and the species dependent on it.
Canadian ports are no stranger to concerns over mercury contamination as well. Just last week, the Thunder Bay Public Advisory Committee sent a letter to local MPPs, Port Authority reps, and local media lamenting the lack of clean up for mercury in the North Harbour of Thunder Bay.
Kerfoot tells Mills that the goal was to compare mercury deposits with methyl mercury deposits to create a timeline and see how long it takes for methylation to occur. He says that their results “reveal that methylation occurred at the time of mining operations and shortly afterwards, with an apparent time lag of 20 to 40 years.”
To flesh out the findings, Kerfoot wants to scale up the next step of research. This will help understand the time lag, and draw more connection between local economic activity and regional environmental impact. He suggests that the research in Keweenaw gives other researchers a baseline for comparison at similar sites around Lake Superior.
Hopefully the publishing of new research can stimulate discussion around remediation projects to clean up the contamination, such as the proposed measures in Thunder Bay’s North Harbour and other affected areas.
A copy of the Journal of Great Lakes Research article is below.