http://www.smithsonianmag.com/science-nature/mining-tar-sands-produces-much-more-air-pollution-we-thought-180949565/#ixzz2sMh46qDA
[Multiple images and links in on-line article.]
Mining Tar Sands Produces Much More Air Pollution Than We Thought
Research shows that emissions of a class of air pollutants are two to
three orders of magnitude higher than previously calculated
By Joseph Stromberg
February 3, 2014
Last week, the U.S. State Department released a report indicating that
the proposed Keystone XL pipeline, which would carry oil from Western
Canada's Athabasca oil sands to the U.S., wouldn't have significant
environmental impacts. It's worth noting, though, that the report didn't
say that extraction from the oil sands itself won't have environmental
impacts—just that this mining will proceed with or without the pipeline
being built.
Your feelings on the pipeline aside, it's well-established among
scientists that extraction of oil from these oil sands (also known as
tar sands) is environmentally dicey. The petroleum found in them doesn't
flow easily like conventional crude—it's a sticky, viscous type formally
known as bitumen but more commonly known as tar—so companies have to
resort to alternate measures, either surface mining (digging up the rock
or sand covering the oil-laden sediment) or injecting steam to get it
out of the Earth.
This uses up an enormous amount of water, distributes toxic metals into
the surrounding watershed and perhaps most important leads to an
estimated 14 percent higher level of greenhouse gas emissions than
conventional oil, because some natural gas must be burned simply to
convert the bitumen into a usable form.
To this list of concerns, we can now add another. A new study, published
today in Proceedings of the National Academy of Sciences, shows that
production in the Athabasca oil sands region is leading to the emission
of levels of polycyclic aromatic hydrocarbons (PAHs) two to three orders
of magnitude higher—that's one hundred to one thousand times
greater—than previously thought. These higher levels of PAHs in the area
aren't imminently dangerous (they're comparable to levels found in urban
areas, which result from burning gasoline in cars and trucks), but
they're significantly higher than reported in mining companies'
environmental impact assessments and Canada's official National
Pollutant Release Inventory.
Frank Wania and Abha Parajulee, environmental scientists at the
University of Toronto, came to the finding by looking at previous
estimates for the PAH emissions that result from mining (gleaned from
the pollutant release inventory and the mining companies' environmental
impact assessments) and comparing them to levels of PAHs that they
measured in the air in the Athabasca region.
"We found that these estimates are insufficient to explain what's being
measured in the environment," Wania says. "The concentrations of PAHs
that should be out there, based on these assumptions, are far too low."
The problem: these environmental impact assessments, Wania and Parajulee
found, only consider PAHs that are directly released into the air during
the oil extraction process itself. But the process generates huge
amounts of wastewater that's collected in tailing ponds, and this
wastewater contains significant amounts of PAHs.
Impact assessments considered these PAHs "disposed," Wania says. "But
when they get mixed up with hot water, that creates ideal conditions for
the PAHs to mobilize and enter the atmosphere." When he and Parajulee
created a new model that included PAHs evaporating from tailing ponds in
their model, they arrived at estimated levels of PAHs in the atmosphere
that were much closer to what's been observed.
Lastly, the researchers created an inverse model—one that started with
observed levels of PAHs in the environment, and then calculated the
levels of PAH emissions from mining that would be needed to explain
them—and found that the true amount generated by mining, processing and
wastewater storage is likely two to three orders of magnitude higher
than previously thought. Several other mechanisms, including PAH-laden
dust being blown into the air after the ground is disurbed by mining,
could account for the discrepancy.
As noted, the measured levels of PAHs aren't necessarily alarming, but
the EPA does list them as priority pollutants [PDF] because in
animal-based lab experiments they've led to tumors, interfered with the
immune system and caused reproductive problems. "We live with these
concentrations day in and day out in places like Toronto," Wania says,
"but it doesn't mean that there are no health consequences."
If nothing else, it is concerning that throughout decades of oil
extraction in Athabasca, environmental impact assessments have
dramatically underestimated the emissions levels of a key air pollutant.
The finding provides one more reason to be worried about how oil sand
extraction affects the environment.
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