Study: Oil Sands Pollutants Were Underestimated
The emission levels of some pollutants from the Athabasca oil sands may be higher than previous official estimates, according to researchers at the University of Toronto. The focus of the study, polycyclic aromatic hydrocarbons (or, PAHs), are listed as priority pollutants by the U.S. Environmental Protection Agency, and known to exhibit carcinogenic and mutagenic properties.
“When dealing with chemicals that have such great potential to harm people and animals, it is absolutely vital that we truly understand how, and how much they are being released into the environment,” said Abha Parajulee, lead author of the paper.
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Previous models for studying the oil sand’s pollutants focused solely on direct atmospheric emissions stemming from the bitumen extraction process and have found PAH emissions to be within acceptable limits. The paper, published Monday in the Proceedings of the National Academy of Science, argues that indirect emissions, such as evaporation from tailings ponds or wind erosion of on-site petroleum coke, are a greater contributor and have been underappreciated by regulators. These indirect emissions models better predicted PAH levels found in samples from the Athabasca oil sands region.
The Athabasca oil sands, the largest oil reserve in Alberta, contains 4,800 square kilometers of surface minable bitumen deposits. The bitumen is extracted from up to 100 meters below the surface and is processed using hot water. The residual fluids, which contain these PAHs, in addition to bitumen, sand, clay, and dissolved metals are then contained in on-site tailings ponds. Further residual material, known as petroleum coke, is generated after the bitumen is upgraded and often remains on-site as well. This petroleum coke also contains heavier PAHs not released prior to upgrading.
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