Natural mixing of lake waters may resuspend contaminants deposited in Quesnel Lake by the Mount Polley mine spill, according to scientists who have been studying the lake since the spill in 2014.
Natural mixing of lake waters may resuspend contaminants deposited in Quesnel Lake by the Mount Polley mine spill, according to scientists who have been studying the lake since the spill in 2014.
The new paper, published recently in Water Resources Research, found that turbidity, or cloudiness, in portions of B.C.’s Quesnel Lake increases each spring and fall, when the lake mixes from top to bottom in a natural process called turnover.
The source of the turbidity appears to be the resuspension of spill-related material from the bottom of the lake, raising concerns about contaminants being reintroduced to the water column.
“During the first turnover after the spill, mixing brought suspended sediment to the surface, turning the previous clear-blue lake to bright green. Twelve months after the spill, the suspended sediment loads had substantially reduced, and the lake waters had appeared to return to their pre-spill state—but it turns out this was only temporary,” said researcher Andrew Hamilton, who did the work as a postdoctoral fellow at UBC and at the University of Alberta.
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Image via Tyler Halverson, UNBC.
