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Environmental Impacts of Mining: Suface & Groundwater
Contamination
Water becomes easily contaminated at mine sites when it comes into
contact with waste rock and tailings. Surface water and groundwater
can run off site contaminating downstream water bodies with highly
acidic, metal laden wastewater. For more information on this topic
see, the acid mine drainage formation
section. Water can also become contaminated with toxic chemicals
used for processing mine materials such as cyanide, petroleum products,
oil, solvents, acids, and reagents. For more information on this
topic, see the cyanide and other chemical
releases section.
Damming
Dams have gained much recent attention concerning their environmental
and economic impacts on the land, animals, and humans. Dams tend
to disrupt nature's equilibrium between the land and the rivers
that are broken due to damming. This disruption of equilibrium is
akin to the disruptions created by mining. The consequences of damming
can not only affect the watershed where the dam is located but it
can also affect the web of life it supports. Some of the environmental
impacts are discussed in the following paragraphs and additional
references are also given.
Dams have numerous environmental impacts. The reduction of water
flow from a river can change the landscape downstream of the dam,
which in turn can affect the ecosystem's flora and fauna. A dam
holds back sediments, especially the heavy gravel and cobbles. The
river, deprived of its sediment load, seeks to recapture it by eroding
the downstream channel and banks, undermining bridges and other
riverbank structures. The erosion effect deepens the channel which
will in turn lower the groundwater table along a river, threatening
vegetation and local wells in the floodplain and requiring crop
irrigation in places where there was previously no need. The depletion
of riverbed gravels reduces habitat for many fish that spawn in
the gravelly river bottom, and for invertebrates such as insects,
mollusks, and crustaceans.
The dammed sediments can also cause more far-reaching affects such
as coastal erosion. In addition, dams alter the flow pattern of
a river, both reducing its overall volume and changing its seasonal
variations. The alteration of flows reaching a river's estuary,
where fresh water meets the sea, is a major cause of the precipitous
decline of sea fisheries.
Dams also prevent flooding events downstream which alter the river
and floodplain ecosystems that have closely adapted to a river's
flooding cycle. The native plants and animals depend on the river's
variations for reproduction, hatching, migration, and other important
lifecycle stages. Annual floods deposit nutrients on the land, flush
out backwater channels, and replenish wetlands. It is generally
recognized by biologists that dam building is the single most destructive
element of many factors causing the rapid disappearance of riverine
species. In addition, dams present a barrier for certain fish species,
such as salmon, that migrate upstream to spawn. These environmental
consequences should be closely reviewed before damming projects
are initiated. The environmental problems they create could negate
the environmental problems we are attempting to solve by reclaiming
mine lands.
For more information on concerning the environmental impacts of
damming, check out the following informative websites:
High Consumption
Massive quantities of water are often necessary on mine sites for
many operations. The most significant of these, water use for processing
minerals, along with the other water consuming processes can cause
drawdown
of the groundwater table. Drawdown can reduce the amount of water
available for recharging wetlands and surface water bodies, thereby
affecting any organisms that depend on those waters.
Problem | Compliance
| Health & Safety | Sampling
| Analytical | Data
Quality
Site Assessment | Prediction
| Construction | GIS
| Monitoring & Assessment
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