Lake Data Reveal Oil Sands Impacts

New measurements on the ecological impact of Canadian oil sands mining and processing operations have provided the first clear evidence that concentrations of toxic polycyclic aromatic hydrocarbons (PAHs) are on the rise in the wilderness environment of northern Alberta. The findings may lead to tighter oil sands emissions controls on PAHs, mercury, CO₂, and other pollutants.

Using a combination of radioisotope dating and mass spectrometry to analyze sediment layers in core samples from six small lakes, researchers say they have recorded levels of anthracenes, pyrenes, and dibenzothiophenes up to 23 times greater than natural background levels, and they are rising (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1217675110).

Scant environmental monitoring data have been collected in northern Alberta since commercial extraction and processing operations began there in the 1960s. The study was carried out by Joshua Kurek and John P. Smol of Queens University, in Kingston, Ontario, along with colleagues from Environment Canada.

“This study is significant in showing that the increase in PAHs has occurred almost in lockstep with increased oil sands production,” says David W. Schindler, an ecologist at the University of Alberta whose group studies oil sands pollutants.

Oil companies, government agencies, academic scientists, and environmental groups have been striving to find a balance in tracking and controlling emissions from the lucrative oil sands that is acceptable to all parties.

An industry-funded monitoring program began in 1997, and so far it has reported that levels of PAHs and other pollutants have not risen significantly above natural background levels. However, some scientists and environmental groups have criticized the program for not being sufficiently rigorous. A separate Canadian government-sponsored monitoring program was created last year to address that concern.

The microgram amounts of PAHs per gram of sample detected in the new study are lower than those found in urbanized areas, which are impacted by vehicle emissions and coal power plants, Schindler explains. “But it is clear that if tighter controls on PAH emissions are not imposed, the lake sediments will be approaching Canadian guidelines for toxicity soon,” he says.