View of tailings ponds looking south over the Syncrude processing facilities and upgrader north of Fort McMurray, Alberta.
Toxic Tailings Ponds
During the process of separating bitumen from the tar sands,
large amounts of water are mixed in with the sand, and once the oil
has been removed, the leftover mixture of water, sand, clay and
residual bitumen - known as tailings - has to be stored in a stable
location so that the solution can settle and separate. The storage
facilities are known as tailings ponds. Because each cubic metre
of bitumen extracted results in three to five cubic metres of
tailings that need to be stored, the tailings ponds are so enormous
they can be seen by the naked eye from outer space. Other
"wastewater" is also stored in human-made holding lagoons such as
sewage, water used for cooling, and water that has come into
contact with coke, asphaltenes, sulphur, or heavy metals. This
tactic is supposed to prevent the contamination of groundwater and
river systems, but there is concern that this is not working
properly.
What is so toxic about these ponds?
In most mining operations, harsh chemicals are needed to
separate the minerals from the sand or rock that they are embedded
in. For example, in gold or copper mining, arsenic and cyanide are
often used, so tailings in those operations are extremely
poisonous. In the tar sands, naphtha and paraffin are used, but
they are supposed to be separated from the water before it is
pumped into the tailings pond.
However, the byproducts of the petroleum itself are dangerous
and known to kill the microorganisms which would ordinarily be
present in a river or natural wetlands. Scientists state that the
most dangerous contaminant in tar sands tailings water is
naphthenic acid, a natural constituent of petroleum that becomes
dissolved and concentrated in the hot water used to process the tar
sands. Repeated exposure to naphthenic acid can have adverse
health effects upon mammals, causing liver problems and brain
hemorrhaging, and higher concentrations lead to more serious
effects. Another component of the tailings is alkyl-substituted
polyaromatic hydrocarbon, which causes deformities and even death
to birds exposed to it.
Besides the toxic chemicals that are contained within the
tailings, the water in these storage facilities attracts
methanogenic bacteria, which produce methane, a greenhouse gas.
The methane bubbles change the composition of the tailings pond and
make some of the other dangerous toxins in the water more
concentrated.
The oil companies' response to these dangers is to fire airguns
around the tailings ponds to prevent any birds and animals from
coming near it. A more serious risk is that these ponds are
leaking into the groundwater in the area, and into the Athabasca
River. Another fear is that companies will stop operating in the
area (if the oil runs out, or if profit margins go down), and stop
maintaining the facilities.
Water Pollution
Naphthenic acids are persistent and hard to disperse from the
environment. They are released in high concentrations from tar
sands projects, so people who live downstream have serious fears
about contaminated water, fish and wildlife. Mercury contamination
is another risk, because when the wetlands which originally covered
the tar sands are drained, high concentrations of mercury can be
released into the surrounding water bodies.
Recently, people living in Fort Chipewyan (a First Nations
community downstream from the tar sands projects) began to
publicise their concerns about the effects of water pollution on
their health. Since tar sands development has been accelerating
over the past few years, they have noticed greater incidences of
cancer and diseases like lupus and multiple sclerosis in their
community.