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Environmental Problems From Mine Tailings
Mine Tailings and the Environment
by Frederic Beaudry
Tailings are a type of rock
waste from the mining industry.
When a mineral product is
mined, the valuable portion is usually embedded in a rock matrix called ore.
Once the ore has been
stripped of its valuable minerals, sometimes through the addition of chemicals,
it is piled up into tailings.
Tailings can reach immense
proportions, appearing in the form of large hills (or sometimes ponds) on the
landscape.
Tailings
deposited as large piles can cause a variety of environmental problems:
· Slumps, landslides. Tailing piles can be
unstable, and experience landslides.
In 1966 in Aberfan, Wales, a
hill of mining debris famously collapsed onto buildings, resulting in 144
deaths.
There are also cases where
wintertime avalanches occurred on tailings, with loss of life for residents
below.
· Dust. Dry tailing deposits contain
small particles that are picked up by the wind, transported, and deposited on
communities nearby.
In the tailings of some silver
mines, arsenic and lead is present in the dust in high enough concentrations to
cause serious health problems.
· Leaching. When rain falls on tailings,
it leaches away materials that can create water pollution, for example lead,
arsenic, and mercury.
Sulfuric acid is sometimes
produced when water interacts with tailings, or it can be a by-product of ore
processing.
As a result, highly acidic
water leaks from the tailings and disrupts aquatic life downstream.
Tailings from copper and
uranium mining often produce measurable levels of radioactivity.
Tailing Ponds
Some mining wastes become very fine after they have been ground
up during processing.
The fine particles are then
generally mixed with water and piped into impoundments as a slurry or sludge.
This method cuts down on dust
problems, and at least in theory, the impoundments are engineered to let excess
water flow out without leaking tailings.
Coal ash, while not a type of
tailing, is a coal burning by-product stored the same way, and carrying similar
environmental risks.
In
reality, tailing ponds also carry several environmental risks:
· Dam failure. There have been numerous
instances where the dam holding back the impoundment collapsed.
The consequences to the aquatic
communities below can be serious, for example in the case of the Mount Polly
Mine Disaster.
· Leaks. Tailing ponds can be hundreds
of acres in size, and in those cases leaks into surface and ground waters are
probably inevitable.
The heavy metals, acids, and
other contaminants end up polluting groundwater, lakes, streams, and rivers.
Some very large ponds in
Canada’s tar sands operations leak large amounts of tailings in the
underlying soil, in the aquifer, and ultimately into the nearby Athabasca
River.
· Wildlife exposure. Migrating waterfowl has been
known to land on tailing ponds, and in some cases with dramatic consequences.
In 2008, about 1,600 ducks died
after landing on a tar sands tailing pond in Alberta, contaminated by floating
bitumen, a tar-like substance.
However, simple deterrent
measures can reduce that risk significantly.
Frederic Beaudry is an associate professor
of environmental science and a wildlife biologist with interests in a broad
range of environmental issues.
Experience
Dr. Beaudry teaches courses in environmental
sciences at Alfred University, New
York. Prior to teaching, he worked as a wildlife biologist focusing on the
ecology and conservation of birds and turtles. He has authored several
scientific papers on land use and conservation. His current research examines
land use changes and their effects on bird and amphibian communities.
Education
Dr. Beaudry has a BS in Biology from the
Université du Québec à Rimouski, a master's degree in Natural Resources from
Humboldt State University, and a PhD in Wildlife Ecology from the University of
Maine. He conducted postdoctoral research at the University of
Wisconsin-Madison.
Frederic Beaudry
"Strong science has greatly developed our
understanding of environmental issues in the last decade. I am hoping to
connect readers with sound information about new developments affecting our
air, water, soil, and biodiversity. We are in charge of our health, that of our
land, and of the plants and animals that depend on it."
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