By Nicola Jones

Canada's tar sands mining operations seem to be raising the levels of toxins in local rivers, according to a study released today. The report finds that levels of polycyclic aromatic compounds (PACs) are higher downstream of mining activity, and can be detected in concentrations high enough to merit concern about the development of fish eggs.

The authors note that their results contradict some government and industry claims that these compounds arise from natural erosion of the surrounding oily landscape and are not a cause of environmental concern.

"Industry's response has always been 'of course there are carcinogens in the water, there's a natural source,'" says lead author David Schindler of the University of Alberta, Edmonton. "But it defied logic to think that all that was going in was natural."

The main body that monitors pollution in the area--the Regional Aquatic Monitoring Program (RAMP)--has typically found low to undetectable levels of PACs in river water, and that their flow into the main river delta has not gone up since 1997, which would indicate that they are not linked to mining. RAMP, set up by the Alberta government in 1997, is composed of representatives from the government, aboriginal communities, environmental groups and industry.

In the study, to be published by the Proceedings of the National Academy of Sciences this week, the authors says that RAMP suffers from "serious deficits," such as an inconsistent sampling design, a lack of strong government leadership, and datasets that aren't open to the public. In a response to Nature (Scientific American is part of Nature Publishing Group), RAMP said that it employs scientifically credible methodology, and has typically restricted access to its data in order to encourage membership--a practice that they are considering revising.

Crude oil

The Albertan tar sands are thought to contain 173 billion barrels of recoverable oil reserves, making it the second largest reserve on the planet after Saudi Arabia. The tar sands are scooped up by giant trucks, blasted with water, and upgraded to crude oil in chemical plants. There are concerns that this pollutes the local environment with metals such as arsenic and mercury, naphthenic acids and PACs. Some of these are carcinogenic or toxic.

The study's authors looked at water samples from the Athabasca river and its tributaries upstream of the tar sands area. They compared them to samples downstream of the tar sands but upstream of any mining, as well as downstream of mining activities. There was a small increase in PACs for both downstream samples in winter, and a large, 10-50-fold increase in PACs downstream of mining in summer when the river is not covered with ice and so more open to pollutants. Areas with more extensive mining development were linked to higher levels of PACs. The highest levels detected were about 0.7 micrograms per litre; 0.4 micrograms per litre can be toxic to fish embryos, the authors note.

The researchers also looked at snowpack samples in winter, and found elevated levels of PACs near the stacks of an oil-upgrading facility. The pollution could be detected up to 50 kilometres away. "When you look down the river, the snow looks grey," says co-author Erin Kelly. "When you melt it you get an oily black residue on top of it."

Peter Van Metre, a hydrologist with the US Geological Survey in Austin, Texas, says more work is probably needed to unpick the question of whether the stream samples are really higher in PACs than they would be if mining was absent. Regardless of this, he says, "the strength of paper is to show there are some significant local releases, and some questions about the impacts on the fish." The concentrations found in the survey are relatively low in comparison to the Canadian aquatic guidelines, he notes, but still worth investigating.

Industry watch

"There's been a lot of concern about inadequate monitoring for many years," says Simon Dyer, with the environmental group the Pembina Institute in Edmonton. "There have been a number of critiques of RAMP to suggest it's scientifically not adequate." The Pembina institute withdrew from RAMP eight years ago because of concerns over a lack of government oversight and industry dominance, Dyer says. RAMP says it has responded to the criticisms brought up in peer review, and that less than 50 percent of its voting members are from industry.

Preston McEachern, a limnologist with Alberta Environment, a government body that participates in RAMP and regulates pollution in the region, says it is industry's responsibility to monitor their own water emissions. Alberta's government spends Can$400,000 (US$380,000) a year auditing these reports. He notes that the government has been working with the University of Victoria to develop isotopic tracers that can untangle natural erosion from mining pollution, which is a tricky problem. "It's not like we're trying to whitewash," he says.

"It's a bad idea to have industry monitoring itself," counters Schindler. "Sort of like abolishing the police and asking people to pull over if they see they're speeding and report themselves."

Schindler recommends that the federal government takes control of the monitoring programme and ensures that the data are made public. He also recommends the installation of scrubbers on the upgrading stacks, wetting down roads to reduce dust from mining trucks, and restricting mining operations from going right to the water's edge.

Press officer Travis Davies of the Canadian Association of Petroleum Producers, the body that represents the tar sands industry, says the organization does not comment on scientific papers prior to publication.