We haven’t heard much about the Canadian oil sands in recent months. The low price of oil on the world market has lessened the enthusiasm to produce oil from unconventional sources, and the decision not to build the Keystone XL pipeline gave environmentalists a welcome victory in their battle to prevent global warming.
But in the northern reaches of Alberta, oil production continues unabated. The cost of production of crude oil from oil sands (about $35 to $45/barrel) is still profitable as long as the price of oil on the world markets stays above $50 per barrel.
All petroleum emits carbon dioxide when it is burned, but the release of CO2 from gasoline produced from oil sands is about 20 percent higher than that from conventional oil produced in the United States. The additional CO2 stems from the need to “roast” the thick oil-sand materials, known as bitumen, to release the lighter organic fractions that can be shipped to refineries by railcar and pipeline and burned in internal combustion engines.
When the bitumen is removed from the oil-sand deposits, the affected areas are supposed to be restored to allow natural vegetation and native ecosystems to reestablish. But recent studies indicate that the nitrogen cycling in reclaimed areas does not resemble that in undisturbed ecosystems within the region.
Mining and roasting of oil sands have other impacts on the environment—some local and some regional—that have received less attention than their contributions to global warming. Emissions of nitrogen oxides (NOx) and sulfur dioxide (SO2) yield acid rain, as well as excessive deposition of nitrogen in boreal peatlands that have developed for millennia under low-nutrient conditions. The nitrogen acts like a fertilizer that will surely change these ecosystems, just as it has in reclaimed areas.
The production of oil from the sand deposits also emits a variety of trace metals to the atmosphere, including lead, cadmium, arsenic, and mercury, that are all known human toxins. And the oil sands operations are a large source of volatile organic compounds that form small, breathable particles in the atmosphere, known as secondary organic aerosols, which are harmful to human health.
One might argue that these emissions are best located in remote regions rather than in areas occupied by many people, but their effects are not local. Small aerosols are carried long distances in the atmosphere and are the cause of much excessive human mortality from air pollution worldwide.
The commodity prices for crude oil will surely rise again as supplies tighten and worldwide demand for petroleum increases. Oil sands will return to the limelight. As we fill our gas tank, it is easy to overlook environmental impact that is not close at hand. Not many of us will see the destruction of thousands of acres of boreal forest in Alberta, (although Google Earth is a good place to start.) Still, what goes on in the far north can affect us all. In addition to recognizing its effect on our climate, we need to ensure that inadvertent releases of unhealthy substances from oil sand operations are not overlooked and are properly regulated.
Reference
Cai, H., A.R. Brandt, S. Yeh, J.G. Englander, J. Han, A. Elgowainy, and M.Q. Wang. 2015. Well-to-wheels greenhouse gas emissions of Canadian oil sands products: Implications for U.S. petroleum fuels. Environmental Science and Technology 49: 8219-8227.
Liggo, J. and 24 others. 2016. Oil sands operations as a large source of secondary organic aerosols. Nature 534: 91-94.
Lynam, M.M., T. Dvorch, J.A. Barres, M. Morishita, A. Legge, and K. Percy. 2015. Oil sands development and its impact on atmospheric wet deposition of air pollutants to the Athabasca oil sands region, Alberta, Canada. Environmental Pollution 206: 469-478.
Masse, J., C.E. Preston, C. Muller, and S.J. Grayston. 2016. Gross nitrogen transformation rates differ in reconstructed oil sand soils from natural boreal-forest soils as revealed using a 15N-tracing method. Geoderma 282: 37-48.
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