Sediment at the end of the Athabasca River - 200 km downstream from oil sands mines - doesn’t have higher concentrations of metals than what would be there naturally, according to a Waterloo study.

The results were found after a research team drilled down into the sediment of floodplain lakes at the Athabasca Delta, extracting sediments that were carried by the Athabasca River as long as 300 years ago. By comparing metal concentrations from these historic sediment samples to current values in river bottom sediment, researchers were able to determine that the oil sands mines have not yet polluted the area studied.

Sediment cores like a time machine

Roland Hall, a biologist in Waterloo’s Faculty of Science, says studying sediment that was supplied by Athabasca River floodwaters before commercial oil mining is like a time-machine that lets you travel back in time. The pre-industrial sediments provide baseline data for comparison so scientists can determine how much of the metals in the sediment are naturally occurring and how much are the result of the commercial oil extraction that began in the late 1960s.

Professor Roland Hall and doctoral student Matthew Elmes

Professor Roland Hall and doctoral student Matthew Elmes collect sediment samples from flood prone lake (photo credit: Brent Wolfe)

Studying the impact of oil sands development is complicated by the fact that erosion of bitumen-rich riverbanks naturally releases substantial quantities of metals and other contaminants into the river.

Research published in peer-reviewed journal

The study, funded by Suncor, appears in the peer-reviewed scientific journal Environmental Research Letters. The team measured eight priority metals, including nickel, vanadium and zinc, in sediments taken from floodplain lakes that were supplied by river floodwaters before the industrial era.

“The detection of river pollution is often hampered by a lack of knowledge about pre-industrial contaminant levels,” said Johan Wiklund, lead author on the study and postdoctoral researcher in Waterloo’s Department of Biology. “This new methodology can be applied to any river around the world.”

Environmental concerns around oil sands 

The extraction of oil from the Athabasca region in Alberta has been highly controversial because of concerns the industry is polluting the Athabasca River, which runs through the heart of the oil sands. Hall’s team is studying the delta, 200 kilometres downstream from where the oil sands are being mined, because that’s where health and environment concerns have been expressed by the Athabasca Chipewyan First Nation, Mikisew Cree First Nation and Métis residents, and it is where the river’s sediments and contaminants get deposited.

Oil sands development

Oil sands development along the Athabasca River

Researchers will study oil sands impact further upstream

“This research is an important step in learning the extent of the oil sands’ industrial impact on the region,” said Hall. Next, the research team plans to reconstruct pre-industrial baselines for metals in the Athabasca River sediment further upstream where oil sands mining and processing activities occur.

“Our study does not address concerns of river sediment pollution closer to the oil sands development,” said Hall. “Up until now, pre-industrial baseline levels of contaminants were not known, which has undermined the ability of monitoring programs to determine if oil sands development has been polluting the river. We now have a way to obtain these critical baseline data.”

The paper’s authors also include Geography and Environmental Studies Professor Brent Wolfe of Wilfrid Laurier University, and Earth and Environmental Sciences Professor Tom D. Edwards, Biology Research Associate Andrea Farwell and Biology Professor D. George Dixon of the University of Waterloo.