It
takes a lot of energy to extract heavy, viscous and valuable bitumen
from Canada’s oil sands and refine it into crude oil. Companies mine
some of the sands with multi-story excavators, separate out the bitumen,
and process it further to ease the flow of the crude oil down
pipelines. About 1.8 million barrels of oil per day in 2010 were
produced from the bitumen of the Canadian oil sands—and the production
of those fossil fuels requires the burning of fossil fuels.
In
the first look at the overall effect of air pollution from the
excavation of oil sands, also called tar sands, in Alberta, Canada,
scientists used satellites to measure nitrogen dioxide and sulfur
dioxide emitted from the industry. In an area 30 km (19 miles) by 50 km
(31 miles) around the mines, they found elevated levels of these
pollutants.
“For
both gasses, the levels are comparable to what satellites see over a
large power plant – or for nitrogen dioxide, comparable to what they see
over some medium-sized cities,” said Chris McLinden, a research
scientist with Environment Canada, the country’s environmental agency.
“It stands out above what’s around it, out in the wilderness, but one
thing we wanted to try to do was put it in context.”
The
independent report on the levels of these airborne pollutants, which
can lead to acid rain if they are in high enough concentrations, is a
part of Environment Canada’s efforts to monitor the environmental impact
of the oil sands’ surface mines, McLinden said. While some land-based
measurements have been taken at particular points by other researchers,
and a NASA airplane made another set of localized measurements, no one
had calculated the overall extent of the oil sands’ air quality impacts
including the giant dump trucks, huge refining facilities where the
bitumen is processed, and more.
To
do that, McLinden and his colleagues turned to satellite data. Several
satellites orbiting Earth detect sunlight that passes through the
atmosphere and is reflected back up to the space. Based on the patterns
of reflected wavelengths, scientists can calculate the concentration of
certain gasses—in particular nitrogen dioxide and sulfur dioxide. It’s a
relatively new way to study pollution over small areas, he said.
The study is published this week in Geophysical Research Letters, a publication of the American Geophysical Union.
The
scientists found that sulfur dioxide amounts peaked over two of the
largest mining operations in the Alberta oil sands, with a peak of
1.2×1016 molecules per square centimeter. Nitrogen dioxide
concentrations reached about 2.5×1015 molecules per square centimeter.
When researchers looked at the concentrations over the years using older
satellite information, they found that the amount of nitrogen dioxide
increased about 10 percent each year between 2005 and 2010, keeping pace
with the growth of the oil sands industry.
“You’d
certainly want to keep monitoring that source if it’s increasing at
that rate,” McLinden said. “There are new mines being put in, they’re
pulling out more oil.”
It’s
important to examine the overall impact of the excavation and
processing from the oil sands, said Isobel Simpson, an atmospheric
chemist with the University of California at Irvine. She was not
involved in this study, but previously participated in the
airplane-based research of air quality over the oil sands.
“There
are so few independent studies of oil sands,” Simpson said. The new
study is something scientists haven’t been able to do before—to “see the
big picture and the birds-eye view of the impact of emissions from the
oil sands industry,” she said. She called for broader, future studies
that would measure additional pollutants and map their extents. With the
oil sands industry expanding, she said, the area needs more monitoring.
Air quality over the Canadian oil sands: A first assessment using satellite observations