A new study suggests industrial discharge from a paper mill in northern Ontario is exacerbating mercury contamination in a nearby river system and its fish.

Researchers from the University of Western Ontario say that while the wastewater from the Dryden, Ont., mill doesn’t contain mercury, the sulphate and organic matter in it contribute to the elevated production of methylmercury in the Wabigoon River.

They say the levels of methylmercury — the most toxic form of mercury — in the river’s fish may be twice as high as they would be without the mill discharge.

The Wabigoon River is upstream from the Grassy Narrows First Nation, which has been plagued with mercury poisoning for more than 50 years.

Brian Branfireun, who led the research team, says the high levels of methylmercury in fish have previously been attributed to mercury contamination from the 1960s, but the wastewater discharge could explain why those levels haven’t decreased further since the 80s.

He says if the sulphate and organic matter going into the river are reduced, there could be a rapid decrease in mercury concentrations in fish, though that won’t resolve the existing contamination in the environment.

“There’s some evidence from other experiments that have been done in North America that that timeline might be in the order of years, as opposed to decades of recovery if we’re talking about a more traditional remediation strategy, which will ultimately need to be forthcoming as well,” he said.

The study was commissioned by Grassy Narrows First Nation and its results were released Thursday “because of the urgency of the situation,” Branfireun said.

“Every minute that there is additional discharge of the sulfate and organic matter into this river, more methylmercury is being formed.”

This report by The Canadian Press was first published May 23, 2024.

The Canadian Press

A new study suggests industrial discharge from a paper mill in northern Ontario is exacerbating mercury contamination in a nearby river system and its fish.

Researchers from the University of Western Ontario say that while the wastewater from the Dryden, Ont., mill doesn’t contain mercury, the sulphate and organic matter in it contribute to the elevated production of methylmercury in the Wabigoon River.

They say the levels of methylmercury — the most toxic form of mercury — in the river’s fish may be twice as high as they would be without the mill discharge.

The Wabigoon River is upstream from the Grassy Narrows First Nation, which has been plagued with mercury poisoning for more than 50 years.

Brian Branfireun, who led the research team, says the high levels of methylmercury in fish have previously been attributed to mercury contamination from the 1960s, but the wastewater discharge could explain why those levels haven’t decreased further since the 80s.

He says if the sulphate and organic matter going into the river are reduced, there could be a rapid decrease in mercury concentrations in fish, though that won’t resolve the existing contamination in the environment.

“There’s some evidence from other experiments that have been done in North America that that timeline might be in the order of years, as opposed to decades of recovery if we’re talking about a more traditional remediation strategy, which will ultimately need to be forthcoming as well,” he said.

The study was commissioned by Grassy Narrows First Nation and its results were released Thursday “because of the urgency of the situation,” Branfireun said.

“Every minute that there is additional discharge of the sulfate and organic matter into this river, more methylmercury is being formed.”

This report by The Canadian Press was first published May 23, 2024.

The Canadian Press