More mercury flowing into Arctic Ocean than thought: Research

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EDMONTON — A new Canadian study shows the amount of mercury flowing into the Arctic Ocean from the Mackenzie River estuary may be higher than originally thought.

"Mercury is important, especially in Canada's Arctic, because it's a neurotoxin in foods," said Jennifer Graydon of the University of Alberta, who published her findings in the journal Science of the Total Environment earlier this year. "So when traditional foods are consumed by First Nations peoples, it's a potential source of methylmercury."

The ingestion of mercury can damage the brain and nervous system, especially in children and fetuses. Previously published studies have shown Western Arctic belugas have higher concentrations of methylmercury than those found in the Eastern Arctic, she said.

"So we thought, let's look at the river, not as a direct source to whales, but at least as a source of mercury to that region."

Graydon and three colleagues tested mercury concentrations in samples taken in 2004 from the Mackenzie River — Canada's longest river — in six floodplain lakes, and upstream of the Mackenzie River Delta, a vital northern ecosystem.

They discovered the total amount of mercury exported from the river during that three-month period was equal to an entire year's worth of mercury calculated in previous studies.

Since then, samples taken over another three years have mostly shown the same concentrations, she said.

This summer, University of Alberta researchers will return to the Mackenzie region after it floods to study mercury levels in the thousands of lakes left behind in the delta by the overflowing river.