The extraction of heavy crude oil from oil sands in Canada is releasing as many as 13 kinds of pollutants into the surrounding air and water, according to a study published in PNAS this week. The independent report directly contradicts the results of the government-administered Regional Aquatic Monitoring Program (RAMP) that claimed neither humans nor the environment were at risk from the oil extraction.

Oil sands are swaths of ground that are laced with heavy crude oil that can be extracted and refined into fuel. Development of oil sands in Canada has been taking place since 1967, but scientists have long been uncertain of the production's impact on the environment.

The RAMP study conducted by the government showed no significant ill effects, but another group of scientists decided to double-check their work. They took samples around an oil sands development facility in Alberta near the Athabasca River from the air and surrounding watersheds, and found some highly contradictory evidence.

Summertime water samples downstream from the development area had concentrations of elements like mercury, arsenic, chromium, and beryllium eight times as high as the background levels. Air samples showed concentrations twice that of the late 1970s, and during the winter, the water concentrations were also twice as high as normal.

The authors speculate that the concentration difference results from the snow capturing many airborne particulates and holding them until summer, when it all melts into the ground and water. The researchers also suspect that many of the airborne contaminants are scattered, lowering their local concentrations but spreading their effects over a wide area.

While this single study doesn't automatically invalidate the RAMP study, this data seriously undermine the government's results and methods, and suggests that the long-term effects of oil sands development bear further scrutiny.

PNAS, 2010. DOI: 10.1073/pnas.1008754107 (About DOIs).