—the peer-reviewed, open access journal of the National Institute of Environmental Health Sciences.
Over the
past five years, production at Canada’s oil sands has reached about 1.3
million barrels per day, more than 1% of global oil production,
according to the Canadian Association of Petroleum Producers (CAPP).
This constitutes the bulk of the 1.9 million barrels Canada exported to
the United States each day in 2008, an amount equal to 12% of U.S. total
petroleum consumption, says Greg Stringham, vice president for oil
sands at CAPP. In North American Oil Sands: History of Development,
Prospects for the Future, a report last updated in January 2008, the
Congressional Research Service estimated production would soar to 2.8
million barrels per day by 2015.
Shallow deposits containing about 8–20% of
Alberta’s oil sands
(depending on the estimate) are surface mined using giant shovels and
enormous trucks. Deeper deposits more than 75–80 meters underground are
accessed using methods such as steam-assisted gravity drainage, in which
steam is used to heat the bitumen so it becomes fluid enough to be pumped to the surface. This is known as in situ production.
Unprocessed
oil sands contain 3–18% bitumen by weight, along with 2–10% water and
80–85% mineral matter (sand, clay, etc.). Bitumen is composed chiefly of
polycyclic aromatic hydrocarbons (PAHs), sulfur,
lead,
mercury,
arsenic,
nickel,
vanadium,
chromium, and
selenium. It contains far more
carbon and far less
hydrogen than conventional crude oil; mixed with crushed stone, bitumen forms
asphalt pavement. Once the bitumen is separated from the ore, it is “upgraded” through the addition of
hydrogen and the subtraction of
carbon,
and natural gas is added to enable the material to be pumped to a
refinery for processing. The remaining water and solids, including a
small amount of unextracted bitumen, are discharged into vast tailings
ponds.
Tailings: A Threat to Water Quality
A
good deal of the controversy about oil sands development centers around
those tailings ponds, which cover more than 130 square kilometers in
northern Alberta, according to the 2008 report 11 Million Litres a Day:
The Tar Sands’ Leaking Legacy from Canada’s Environmental Defence. Some
large tailings ponds are separated by earthen dikes from the Athabasca
River, which joins the Mackenzie River to form the major watershed of
Northwest Canada. The water in these ponds often contains
arsenic,
mercury, PAHs, and other toxics found in the bitumen.
Oil
sands operators maintain interceptor ditches and wells to catch leakage
from the tailings ponds, but the Environmental Defence report
calculated that 11 million liters of contaminated wastewater
nevertheless escapes each day. This rate was based on data from oil
companies’ environmental impact assessments; for ponds for which there
were no publicly available data, the authors calculated an average
seepage rate using industry-reported figures.
Opponents of oil
sands development are concerned about the potential for adverse health
effects if the leaking wastewater contaminates drinking water supplies.
George Poitras, former chief of the Mikisew Cree First Nation, says
chemicals leaking from tailings ponds “affect anybody or anything that
relies on water as a source of drinking or a place to live in [including
fish, moose, and birds]. The majority of our people rely on the
traditional diets, on moose.”
Ecologist Kevin P. Timoney of
Treeline Ecological Research believes the 11 million liters/day estimate
is conservative; the actual rate, he says, is probably much greater. In
A Study of Water and Sediment Quality as Related to Public Health
Issues, Fort Chipewyan, Alberta, published in November 2007, Timoney
described his analysis of published data on water and sediment quality indicators at the titular community, which is located at the northernmost edge of the
Athabasca oil sands.
He noted that Fort Chipewyan lies within a depositional basin in which
metals and other contaminants tend to accumulate in fine-textured
sediments. Concentrations of
arsenic,
mercury, and PAHs are especially high in water and sediment, and many other metals (including
cadmium,
chromium,
cobalt, and
lead) and agricultural chemicals also are present.
Timoney’s
analysis further noted that studies of local fish have shown that all
the walleye and female whitefish and almost all the male whitefish
tested exceeded U.S. guidelines for
mercury
consumption. Although treated local water appeared safe, untreated
water in Lake Athabasca had levels of arsenic, total mercury, and PAHs
sufficient to pose a threat to wildlife or humans.
Aerial
view of a tailings pond north of Fort McMurray, Alberta, Canada. One of
the chief human health concerns associated with oil sands development
is the leakage of contaminated wastewater into drinking water supplies.
(Source: NIEHS; Credit: Jiri Rezac.
Glen Van Der Kraak, a professor in
the Department of Integrative Biology at the University of Guelph,
Ontario, says studies of fish exposed to oil sands wastewater
consistently find
endocrine disruption
and impairments of reproductive physiology. For example, in research
published in the 1 May 2008 issue of Aquatic Toxicology, Van Der Kraak
and colleagues found that goldfish exposed to wastewater from tailings
ponds had dramatically lower plasma levels of testosterone and
17?-estradiol than control fish. The prime suspect behind these effects,
says Van Der Kraak, is naphthenic acids, compounds that are often
present in tailings pond water.
John O’Connor, a doctor who practiced in Fort Chipewyan between 2002 and 2007, first raised the alarm about human cases of cholangiocarcinoma, reporting six possible cases in this community of about 900. This rare
cancer of the bile duct typically strikes about 2 in 100,000 people. In
Alberta, the incidence of cholangiocarcinoma has increased progressively
over the past 30 years, and rates are 2–3 times higher in First Nations
communities compared with non–First Nations populations.
In
August 2007 a working group was convened to support the Alberta Cancer
Board in performing a cluster investigation using guidelines from the
U.S. Centers for Disease Control and Prevention. The number of observed
cancer cases in the community, as determined through the Alberta Cancer
Registry, was compared with the number of cases expected over a 12-year
period. Expected cases were determined by applying yearly Alberta rates
to the Fort Chipewyan population, taking into account the size and
composition of the population.
In the February 2009 report Cancer
Incidence in Fort Chipewyan, Alberta, 1995–2006, the group reported that
only two of the cases in Fort Chipewyan were confirmed as
cholangiocarcinoma. A third case was not a cancer, and the remainder
were confirmed to be other cancers. Given these numbers, the incidence
of cholangiocarcinoma fell within the expected range. However, the study
found higher-than-expected numbers of cancers of the blood and
lymphatic system, biliary tract, and soft tissue (all statistically
significant findings), as well as all cancers combined (51 observed
versus 39 expected cases—a finding deemed to be of borderline
statistical significance). Lung cancers as a whole were within the
expected range, but when women were looked at separately, the number of
cases was 3.5 times higher than expected.
The study was not
designed to determine the cause of any of the cancers observed, and
because of the small population size and limited number of cases, the
working group cautioned that the findings could be due to chance and/or
increased detection. Given that the numbers rose in the latter half of
the 12-year study period, however, the group wrote that closer
monitoring of cancer occurrences in Fort Chipewyan will be justified in
the coming years and that future studies should track a cohort of
residents who have lived in the area within the past 20–30 years.
The
authors also noted that a 2006 analysis of the health status of Fort
Chipewyan residents showed that residents have elevated prevalence rates
of diabetes, hypertension, renal failure, and lupus. All these diseases
have been linked with one or more of the toxics commonly found in
tailings pond water. The working group suggested that, in order to
examine risks for cancer and other chronic diseases, assessment of the
overall health status and risk factor profile of Fort Chipewyan
residents would be needed. Future studies should also evaluate the
occupational history and employment-related migration pattern of the
cancer patients in the community, because many of the Fort Chipewyan
residents work or had worked in the oil sands or uranium industries. As
the authors pointed out, “Previous studies of cancer risk and
occupational exposure have suggested increased risk of leukemia and lung
cancer in oil field workers, and increased risk of leukemia, lung
cancer, and cancers in gallbladder and extrahepatic bile ducts in
uranium miners.”
Scientists
and local subsistence fishers have observed cancerous tumors on
whitefish caught near Fort Chipewyan, a community on the northern edge
of the Athabasca oil sands. A 2009 study reported a higher-than-expected
number of human cancers in the community but was not designed to
determine the cause of those cancers. (Source: NIEHS; Credit: Jiri Rezac)
Long-Term Restoration Challenges
Although
the authors of Cancer Incidence in Fort Chipewyan avoided assigning a
cause for the cancers they observed, many critics of oil sands
development believe it is only a matter of time before a link is
established with tailings pond leakage. Moreover, in his 2007 report,
Timoney asserted that abandoned tailings ponds could pose a major health
threat to surrounding communities for years to come. “While a mine is
in operation, monitoring and pumping of tailing pond leaks is
continuous,” he wrote. “No one knows what will happen when a mine has
exhausted a site, shuts down its operation, and leaves. Tailings pond
abandonment is an unproven technology whose success is predicated on
modeling rather than real world experience. . . . The [Alberta oil sands
formation] is known to be porous with active subsurface water
movements. Billions of cubic meters of contaminated water soon will be
sitting untended, with no active pumping, in abandoned ponds adjacent to
the Athabasca River.”
The challenges of restoring the tailings
ponds and other elements of development sites have been underestimated,
says E.A. Johnson, a professor of biological sciences at the University
of Calgary and co-author of a report on the science behind reclamation
in the oil sands published in The Year in Ecology and Conservation
Biology 2008. “Restorations are usually small projects, a few hectares
in size, but now we are confronted with whole landscapes in which the
reconstruction must start with the central template, the groundwater,
and then the soil. . . . We are going to have to reconstruct the
drainage, the groundwater flow, and these are things about which we have
little knowledge. It is not clear to me that everybody understands how
complicated this is.”
Many years are needed to evaluate a
restoration, Johnson adds. “Traditionally, even in small restoration
projects, it takes much longer than anyone imagines, especially for the
monitoring. This calls for a 40-year attention span or more, and it will
be hard to keep that going.”
According to Alberta’s Oil Sands.
Resourceful. Responsible, a 2008 publication from the government of
Alberta, as of March 2008 approximately 65 square kilometers of land
were in the process of being reclaimed, meaning the land would “be able
to support a range of activities similar to its previous use before oil
sands development.” However, the province has certified only 104
hectares (at a facility run by major producer Syncrude) as restored.
Both
opponents and proponents of oil sands development agree that liquid
tailings are a problem. “We need to prohibit the creation of liquid
tailings that require these tailings ponds,” says Simon Dyer, oil sands
program director at the nonprofit Pembina Institute in Calgary, Alberta.
“There are new technologies that are close to commercialization that
would not require the creation of liquid tailings, but there is no
incentive for companies to implement these when the government is
willing to approve their projects.”
“The ultimate goal is dry
tailings,” agrees Stringham, who notes that the industry is, in fact,
working on near-term solutions, such as injecting carbon dioxide (CO
2) into tailings so the clay can settle more quickly, allowing the water to be drawn off and reused.
A Carbon-Intense Industry
The
carbon intensity of oil sands development poses other environmental
health questions. The extraction and refining of oil sands produces
30–70% more greenhouse gas emissions than conventional oil production,
according to estimates by Alex Farrell and Adam Brandt published in the
October 2007 issue of Climatic Change. If the greenhouse gas impact of
oil sands is calculated to include the CO
2 released when the
fuel is burned, the discrepancy drops to 10–30%, says Aimee Curtright,
an analyst at the RAND Corporation and coauthor of the 2008 report
Unconventional Fossil-Based Fuels: Economic and Environmental
Trade-Offs. “For both [conventional and unconventional] oil, most CO
2 release occurs in burning; the smaller portion of greenhouse gases is related to the production process,” she says.
The primary global impact of oil sands production comes through the release of
greenhouse gases
created when about 800 million cubic feet of natural gas (approximately
10% of Canada’s total natural gas consumption) is burned daily to
create heat for extraction and upgrading, says Stringham. In the 2006
report The Canadian Oil Sands in the Context of the Global Energy
Demand, Eddy Isaacs, director of the Alberta Energy Research Institute,
wrote that 176 cubic meters of natural gas are required to liquefy,
extract, and purify each cubic meter of bitumen produced.
According
to the 2008 Congressional Research Service report, the government of
Canada expects that by 2010 the oil sands will produce half of Canada’s
growth in greenhouse gas emissions and 8% of the country’s total
greenhouse gas emissions. The longer-term picture is even more striking,
says Dyer. “Even under government predictions, oil sands emissions will
triple by 2020. This is inconsistent with meaningful action on climate
change. [Oil] sands . . . are almost single-handedly taking us in the
opposite direction of [the
Kyoto Protocol].”
For
2005 Environment Canada estimated that industry and resource extraction
accounted for 8% of deforestation in Canada, affecting less than 0.02%
of the country's forests. Although deforestation can have adverse
ecologic consequences, the greater greenhouse gas impact of oil sands
development comes from the energy used to extract and refine the
bitumen.(Source: NIEHS; Credit: Louis Helbig)
Chris
Bourdeau, a spokesperson for Alberta Environment, says this is an unfair
characterization of the impact of oil sands. Oil sands produced 33
metric megatons (Mt) of
greenhouse gas
emissions in 2006, he says. Canada’s Kyoto commitment is to reduce
emissions to 6% below 1990 levels. Canadian emissions in 1990 were 594
Mt, whereas emissions in 2006 were 721 Mt. “Canada is 163 Mt over its
Kyoto target,” he says. “Oil sands, with 33 Mt of total emissions, are
not single-handedly taking the country in the opposite direction—there
are many factors.”
That said, the oil sands industry is being
prodded to reduce energy use by Alberta’s Specified Gas Emitters
Regulation, which requires oil sands operators and other industries that
release more than 100,000 metric tons of CO
2 equivalent per year to reduce their “emissions intensity”—or CO
2
equivalents per unit of product—by 12% compared with a baseline
measured during 2003–2005. “Alberta is the only jurisdiction in North
America to have a regulatory system in place that creates mandatory
emission reductions,” says Bourdeau.
Industries that cannot make
the reduction can buy offsets, such as paying for reforestation inside
Alberta or contributing Can$15 per metric ton of CO
2
equivalent to the province’s Climate Change and Emissions Management
Fund. Bourdeau says this program, in its first half-year of operation,
resulted in a total reduction of 2.6 million metric tons of CO
2
equivalent. Although the 12% reduction is a one-time cut, companies
must pay annually for offsets or the technology fund if they cannot make
the reduction. [For more information on carbon offsets, see “Carbon
Offsets: Growing Pains in a Growing Market,” EHP 117:A62–A68 (2009).]
Carbon capture and storage (CCS), in which CO
2
would be transferred to deep underground storage, is touted by oil
sands advocates as the ultimate solution to greenhouse gases releases.
In April 2008 the government of Alberta launched a council, led by
former Syncrude president Jim Carter, to develop a roadmap for
broad-scale implemention of CCS. In July 2008 the government committed
Can$2 billion to support construction of “high-impact” CCS facilities
starting this spring in the expectation that overall greenhouse gas
emissions will be reduced by 5 million metric tons per year by 2015.
However, although many experts believe CCS is viable in theory, it is
largely untested on the scale proposed by the oil sands industry. [For
more information on CCS, see “Carbon Capture and Storage: Blue-Sky
Technology or Just Blowing Smoke?” EHP 115:A538–A545 (2007).]
Uncertain Future
With
President Obama now in office, all sides in the oil sands issue are
pondering the schedule and details on any upcoming restrictions on
greenhouse gases and what those will mean for oil sands development. One
possibility is that the United States will restrict import of fuels
that entail extra releases of greenhouse gases.
But a complete
halt to oil sands extraction is unlikely, and the price of oil could
easily start to rise again. Instead of advocating a halt, most critics
of oil sands development favor simply slowing or stopping expansion.
“First, we want a moratorium on any new development, to stop granting
new permits, new leases, and new in situ development sites,” says Susan
Casey-Lefkowitz, director of the Canada program at the Natural Resources
Defense Council. “We think the governments in Alberta and Canada need
to take stock of what has already happened to the land, the environment,
and the people who live there, and try to remedy some of that harm. If
they go forward, they need to figure out a way to do it that is
environmentally sustainable.”
Can Nanotechnology Make Oil Sands Development Greener?
Some scientists are exploring a nanotechnologic approach to softening
the environmental footprint of oil sands development. Understanding at
the nanoscale how the molecules of heavy bitumen clump together could
help reduce the industry’s thirst for fresh water, says Murray Gray, the
Canada Research Chair in Oil Sands Upgrading at the University of
Alberta. “If we understand better how oil behaves at the molecular
scale, we might find solvents or detergents that separate the oil [from
its native matrix of clay and sand].” Gray says the viscosity of bitumen
results from strong attachment between nearby molecules. He suggests
that nanoscale adsorbents specifically designed to interrupt the
association between the molecules might be able to inhibit the unwanted
clumping. He adds that water-free processes would also eliminate the
need for tailings ponds, reduce the use of fresh water, and dramatically
speed up the process of reclaiming land that otherwise would be devoted
to tailings ponds.
Sergio Kapusta,
chief scientist for materials at Shell, says nanotechnology might
benefit oil sands development in other ways. “Nanoscale filters might be
used to remove salt, heavy metals, and other impurities from tailings
water,” he says. “In future this could help make extraction more
efficient and reduce water consumption.” Kapusta also points to
“nanobubbles”—tiny bubbles of air that attach to bitumen and help it to
float on water—as a further way to help improve bitumen recovery rates |
