Collaborative research by scientists at the University of Ottawa and the Government of Alberta’s Environment and Parks ministry has found that the concentrations of polycyclic aromatic hydrocarbons (PAHs) have increased in lake sediments near in-situ drilling wells since production began at the Cold Lake oil sands development in the 1980s. PAHs, a diverse group of organic contaminants, have been linked to cancer and other adverse health effects in humans.
“When we think of the Alberta oil sands, we typically think of the large excavation pits in the Athabasca region, but the majority of Canada’s bitumen reserves are actually located deep belowground, and are only recoverable using in-situ drilling wells,” says lead author Jennifer Korosi, a professor at York University who was a postdoctoral researcher at the University of Ottawa at the time of study. “Growth in this sector has far outpaced the study of its potential environmental impacts.”
In-situ extraction injects steam into the deposits at high pressure, to heat the bitumen in order to pump it up to the surface, where it can be extracted through the wells. In the spring of 2013, the in-situ industry received national scrutiny when media reported on a large bitumen leak at the Canadian Natural Resources Ltd. Primrose site, on the Cold Lake Air Weapons Range. A report by the Alberta Energy Regulator later concluded that the bitumen leak occurred because of fissures in the bedrock created by high-pressure steam injection, combined with the area’s unique geology.
“The recent bitumen leaks at Cold Lake are an obvious example of the potential environmental impacts of in-situ bitumen extraction, but our study showed a long-term gradual increase in hydrocarbons that suggests there are other pathways for the release of pollutants to the environment outside of these widely reported incidents,” explains Jules Blais, professor of biology and environmental toxicology at the University of Ottawa, who directed the study.
Because there are no long-term monitoring records for pollutants in the region, researchers relied on sediment cores collected from a small lake on the Cold Lake Air Weapons Range, near the site of the 2013 leak, to record the history of environmental contaminants over the last several hundred years. The results, published today in the journal EnvironmentalPollution, found that lake sediments recorded a clear and steady increase in PAHs starting after oil sands operations began in the 1980s. “It is important to note,” adds Blais, “that although these contaminants have clearly increased since operations began, their concentrations still remain low compared to typical urban lakes, and compared to lakes near open-pit mining in the Athabasca oil sands region.”
“Most attention has focused on the open mining pits in the Athabasca, while the potential environmental impacts of the in-situ industry have largely gone unreported,” said Colin Cooke, research scientist with Alberta Environment and Parks and adjunct professor at the University of Alberta, “our study is important because it sheds light on the pressing need to better understand the ways in-situ drilling can release chemicals to the environment.”
For more information, read the full study.