The Athabasca river runs through the city of Fort McMurray, Alta., in this file photo. REUTERS/Todd Korol

OTTAWA - A new study shows aquatic toxins near the Athabasca River have risen in lockstep with oilsands development there, contradicting earlier government assertions the contamination was naturally occurring.

Calling the data a “smoking gun,” lead scientist and Queens University professor John Smol explained that unlike previous studies, which relied on insufficient historical data and produced mere “snapshots” of contaminants in a given area at a given time, the new research used core samples of lake sediment going back to before oilsands development near the Athabasca River began.