Researchers find that pollutants in Canada's Athabasca River are not from natural sources.
Oil-mining operations in Canada's main tar sands region are releasing a range of heavy and toxic metals — including mercury, arsenic and lead — into a nearby river and its watershed, according to a new study.
Research published online yesterday in the Proceedings of the National Academy of Sciences shows that 13 elements classified as priority pollutants (PPEs) by the US Environmental Protection Agency were found in the Athabasca River in the province of Alberta1. Seven of these were present at high enough concentrations to put aquatic life at risk. The findings are also of concern to human health.
Almost all of Alberta's known oil reserves — 172 billion barrels — are found within tar sands. The provincial government expects that oil production will increase from about 1.3 million barrels per day to 3 million barrels per day by 2018.
Tar sands mining and upgrading — the process of extracting fuel from the mix of petroleum and sand or clay — produces sand, water, fine clays and minerals that are contained within tailing ponds.
A team led by ecologist David Schindler of the University of Alberta in Edmonton set out to test the government and oil industry's claims that the concentrations of elements in the Athabasca River and its tributaries were from natural sources and not tar sands development.
The team took samples of surface water from the waterways upstream of the tar sands region and compared them with samples taken within the region — both upstream and downstream of mining projects. The researchers also looked at snow samples from many of the same areas towards the end of winter to look for airborne sources of PPEs, which would be discharged to surface waters when the snow melted.
"Much of the debate on this topic has gone on without science," says Schindler. "But the hypothesis that it [PPEs] is 'all natural' is wanting, to say the least."
He and his team found that there were higher concentrations of PPEs in the Athabasca River downstream of tailing ponds and other tar sands development infrastructure, and in areas downstream of watersheds stripped of soil and vegetation in preparation for mining, than there were at sites upstream of mining projects.
In snowpack samples near development, the researchers found increased concentrations of many toxic metals, including cadmium and copper, as compared to those more than 50 kilometres away from upgraders.
In total, the levels of seven PPEs in both water and snow exceeded those in federal and provincial guidelines set out for the protection of aquatic life.
"In the spring snow melt you'd end up with these high concentrations and low water alkalinity, which makes the toxicity of metals go way up," says co-author Peter Hodson, a fish toxicologist at Queen's University in Kingston, Ontario. "A number of fish species will be at risk during the spring spawning. Others will be hatching out and exposed to the spring freshening of the highly toxic water."
Schindler and colleagues also found other toxic chemicals, known as polycyclic aromatic compounds, at higher concentrations downstream of mining activity, as reported in a December 2009 study2 (see 'Tar sands mining linked to stream pollution').
The main pollution-monitoring body for the area is the Regional Aquatics Monitoring Program (RAMP), which was established in 1997 to assess the state of rivers and lakes in the tar sands region, and is funded by the oil industry. Its steering committee consists of representatives from provincial and federal government, First Nations communities and industry.
The authors of the study say that RAMP's monitoring efforts have "serious defects". Schindler says that RAMP's sampling methods, sites, times and contractors change without proper quality control. He would like to see Environment Canada take over from RAMP, subject the results to peer review and make them available to the public on a regular basis.
Preston McEachern, section head for science, research and innovation at Alberta Environment, a government body that regulates pollution in the region and participates in RAMP, says that the group's study protocols have changed over the years in response to reviewers. He adds that RAMP's data are available to anyone who asks a RAMP member.
"They've put together a fine piece of work. It's in the interpretation where we have some differences," says McEachern about the new study. He stands behind the view that there is a very large natural background load of elements that stems from erosion and ground water and that increases as one goes downstream.
"We need independent monitoring to be taking place if the reliability of RAMP's work is being called into question or if there is conflicting evidence" between RAMP's findings and those of others, says Terra Simieritsch, a tar sands policy analyst with the energy think tank the Pembina Institute in Calgary, Alberta.
Kelly, E. N. et al. Proc. Natl Acad. Sci. USA doi: 10.1073/pnas.1008754107 (2010).
Kelly, E. N. et al. Proc. Natl Acad. Sci. USA 106, 22346-22351 (2009).
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Hoag, H. River metals linked to tar sand extraction. Nature (2010). https://doi.org/10.1038/news.2010.439