Oil Sands Pollutants Underestimated: Report

Wednesday, February 5, 2014 @ 10:02 AM gHale


Emissions of certain hazardous air pollutants are underestimated in the Athabasca Oil Sands Region, according to a new comprehensive modeling assessment of contamination.

The team, led by University of Toronto Scarborough Environmental Chemistry professor Frank Wania and his PhD candidate Abha Parajulee, used a model to assess the plausibility of reported emissions of a group of atmospheric pollutants known as polycyclic aromatic hydrocarbons (PAHs). Many PAHs are highly carcinogenic. The study constitutes the most comprehensive model done for the Oil Sands Region.

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“When dealing with chemicals that have the potential to harm people and animals, it is vital that we have a good understanding of how, and how much they are entering the environment,” said Parajulee, the lead author of a paper on the subject.

PAHs end up released during the process of extracting petroleum from the oil sands. Environmental Impact Assessments have so far only considered the PAHs that release directly into the atmosphere. The risk associated with those direct releases fell within acceptable regulatory limits, officials said.

However, the model used by Parajulee and Wania takes into account other indirect pathways for the release of PAHs not assessed before or deemed negligible. For instance, they found evaporation from tailings ponds – lakes of polluted water also created through oil sands processing – may actually introduce more PAHs into the atmosphere than direct emissions.

“Tailings ponds are not the end of the journey for many of the pollutants they contain. Some PAHs are volatile, meaning they escape into the air much more than many people think,” Parajulee said.

The higher levels of PAHs the UTSC scientists’ model predicts when accounting for emissions from tailings ponds are consistent with what they have actually measured in samples taken from areas near and in the Athabasca Oil Sands Region.

The researchers also found tailings ponds emissions are likely not significant contributors of relatively involatile PAHs to the Oil Sands Region atmosphere. Instead, other emissions sources not taken into account by the environmental impact assessment, such as blowing dust, are probably more important for these chemicals.

The researchers modeled only three PAHs, which they believe are representative of others. Still, they say, their model indicates better monitoring data and emissions information can improve understanding of the environmental impact of the oil sands even further.

“Our study implies that PAH concentrations in air, water, and food, that are estimated as part of environmental impact assessments of oil sands mining operations are very likely too low,” Wania said. “Therefore the potential risks to humans and wildlife may also have been underestimated.”



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