Environmental impacts of mining can occur
at local, regional, and global scales through
direct and indirect mining practices. Impacts
can result in erosion, sinkholes, loss of
biodiversity, or the contamination of soil,
groundwater, and surface water by the chemicals
emitted from mining processes. These processes
also have an impact on the atmosphere from
the emissions of carbon which have effect
on the quality of human health and biodiversity.
Some mining methods may have such significant
environmental and public health effects that
mining companies in some countries are required
to follow strict environmental and rehabilitation
codes to ensure that the mined area returns
to its original state.
=== Erosion ===
Erosion of exposed hillsides, mine dumps,
tailings dams and resultant siltation of drainages,
creeks and rivers can significantly impact
the surrounding areas, a prime example being
the giant Ok Tedi Mine in Papua New Guinea.
In wilderness areas mining may cause destruction
and disturbance of ecosystems and habitats,
and in areas of farming it may disturb or
destroy productive grazing and croplands.
In urbanized environments mining may produce
noise pollution, dust pollution and visual
pollution.
=== Sinkholes ===
A sinkhole at or near a mine site is typically
caused from the failure of a mine roof from
the extraction of resources, weak overburden
or geological discontinuities. The overburden
at the mine site can develop cavities in the
subsoil or rock, which can infill with sand
and soil from the overlying strata. These
cavities in the overburden have the potential
to eventually cave in, forming a sinkhole
at the surface. The sudden failure of Earth
creates a large depression at the surface
without warning, this can be seriously hazardous
to life and property. Sinkholes at a mine
site can be mitigated with the proper design
of infrastructure such as mining supports
and better construction of walls to create
a barrier around an area prone to sinkholes.
Back-filling and grouting can be done to stabilize
abandoned underground workings.
=== Subsidence ===
Salt mining and salt dome collapsing in Assumption
Parish, Louisiana caused the Bayou Corne sinkhole
in 2012. As of August 2013, the sinkhole continues
to expand.
=== Water pollution ===
Mining can have harmful effects on surrounding
surface and groundwater. If proper precautions
are not taken, unnaturally high concentrations
of chemicals, such as arsenic, sulfuric acid,
and mercury over a significant area of surface
or subsurface water. With large amounts of
water used for mine drainage, mine cooling,
aqueous extraction and other mining processes,
increases the potential for these chemicals
to contaminate ground and surface water. As
mining produces copious amounts of waste water,
disposal methods are limited do to contaminates
within the waste water. Runoff containing
these chemicals can lead to the devastation
of the surrounding vegetation. The dumping
of the runoff in surface waters or in a lot
of forests is the worst option. Therefore,
submarine tailings disposal are regarded as
a better option (if the waste is pumped to
great depth). Land storage and refilling of
the mine after it has been depleted is even
better, if no forests need to be cleared for
the storage of debris. The contamination of
watersheds resulting from the leakage of chemicals
also has an effect on the health of the local
population.
In well-regulated mines, hydrologists and
geologists take careful measurements of water
to take precaution to exclude any type of
water contamination that could be caused by
the mine's operations. The minimization of
environmental degradation is enforced in America
mining practices by federal and state law,
by restricting operators to meet standards
for the protection of surface and groundwater
from contamination. This is best done through
the use of non-toxic extraction processes
as bioleaching.
==== Acid rock drainage ====
Sub-surface mining often progresses below
the water table, so water must be constantly
pumped out of the mine in order to prevent
flooding. When a mine is abandoned, the pumping
ceases, and water floods the mine. This introduction
of water is the initial step in most acid
rock drainage situations.Acid rock drainage
occurs naturally within some environments
as part of the rock weathering process but
is exacerbated by large-scale earth disturbances
characteristic of mining and other large construction
activities, usually within rocks containing
an abundance of sulfide minerals. Areas where
the earth has been disturbed (e.g. construction
sites, subdivisions, and transportation corridors)
may create acid rock drainage. In many localities,
the liquid that drains from coal stocks, coal
handling facilities, coal washeries, and coal
waste tips can be highly acidic, and in such
cases it is treated as acid mine drainage
(AMD). The same type of chemical reactions
and processes may occur through the disturbance
of acid sulfate soils formed under coastal
or estuarine conditions after the last major
sea level rise, and constitutes a similar
environmental hazard.
The five principal technologies used to monitor
and control water flow at mine sites are diversion
systems, containment ponds, groundwater pumping
systems, subsurface drainage systems, and
subsurface barriers. In the case of AMD, contaminated
water is generally pumped to a treatment facility
that neutralizes the contaminants. A 2006
review of environmental impact statements
found that "water quality predictions made
after considering the effects of mitigation
largely underestimated actual impacts to groundwater,
seeps, and surface water".
==== Heavy metals ====
Dissolution and transport of metals and heavy
metals by run-off and ground water is another
example of environmental problems with mining,
such as the Britannia Mine, a former copper
mine near Vancouver, British Columbia. Tar
Creek, an abandoned mining area in Picher,
Oklahoma that is now an Environmental Protection
Agency Superfund site, also suffers from heavy
metal contamination. Water in the mine containing
dissolved heavy metals such as lead and cadmium
leaked into local groundwater, contaminating
it. Long-term storage of tailings and dust
can lead to additional problems, as they can
be easily blown off site by wind, as occurred
at Skouriotissa, an abandoned copper mine
in Cyprus.
=== Effect on biodiversity ===
The implantation of a mine is a major habitat
modification, and smaller perturbations occur
on a larger scale than exploitation site,
mine-waste residuals contamination of the
environment for example. Adverse effects can
be observed long after the end of the mine
activity. Destruction or drastic modification
of the original site and anthropogenic substances
release can have major impact on biodiversity
in the area. Destruction of the habitat is
the main component of biodiversity losses,
but direct poisoning caused by mine-extracted
material, and indirect poisoning through food
and water, can also affect animals, vegetation
and microorganisms. Habitat modification such
as pH and temperature modification disturb
communities in the surrounding area. Endemic
species are especially sensitive, since they
require very specific environmental conditions.
Destruction or slight modification of their
habitat put them at the risk of extinction.
Habitats can be damaged when there is not
enough terrestrial product as well as by non-chemical
products, such as large rocks from the mines
that are discarded in the surrounding landscape
with no concern for impacts on natural habitat.Concentrations
of heavy metals are known to decrease with
distance from the mine, and effects on biodiversity
tend to follow the same pattern. Impacts can
vary greatly depending on mobility and bioavailability
of the contaminant: less-mobile molecules
will stay inert in the environment while highly
mobile molecules will easily move into another
compartment or be taken up by organisms. For
example, speciation of metals in sediments
could modify their bioavailability, and thus
their toxicity for aquatic organisms.Biomagnification
plays an important role in polluted habitats:
mining impacts on biodiversity, assuming that
concentration levels are not high enough to
directly kill exposed organisms, should be
greater to the species on top of the food
chain because of this phenomenon.Adverse mining
effects on biodiversity depend a great extent
on the nature of the contaminant, the level
of concentration at which it can be found
in the environment, and the nature of the
ecosystem itself. Some species are quite resistant
to anthropogenic disturbances, while some
others will completely disappear from the
contaminated zone. Time alone does not seem
to allow the habitat to recover completely
from the contamination. Remediation practices
take time, and in most cases will not enable
the recovery of the original diversity present
before the mining activity took place.
=== Aquatic organisms ===
The mining industry can impact aquatic biodiversity
through different ways. One way can be direct
poisoning, higher risk for this occurs when
contaminants are mobile in the sediment or
bioavailable in the water. Mine drainage can
modify water pH, making it is hard to differentiate
direct impact on organisms from impacts caused
by pH changes. Effects can nonetheless be
observed and proved to be caused by pH modifications.
Contaminants can also affect aquatic organisms
through physical effects: streams with high
concentrations of suspended sediment limit
light, thus diminishing algae biomass. Metal
oxide deposition can limit biomass by coating
algae or their substrate, thereby preventing
colonization.
Factors that impact communities in acid mine
drainage sites vary temporarily and seasonally:
temperature, rainfall, pH, salinisation and
metal quantity all display variations on the
long term, and can heavily affect communities.
Changes in pH or temperature can affect metal
solubility, and thereby the bioavailable quantity
that directly impact organisms. Moreover,
contamination persists over time: ninety years
after a pyrite mine closure, water pH was
still very low and microorganisms populations
consisted mainly of acidophil bacteria.
==== Microorganisms ====
Algae communities are less diverse in acidic
water containing high zinc concentration,
and mine drainage stress decrease their primary
production. Diatoms community is greatly modified
by any chemical change pH phytoplankton assemblage,
and high metal concentration diminishes the
abundance of planktonic species. Some diatom
species may however grow in high-metal-concentration
sediments. In sediments close to the surface,
cysts suffer from corrosion and heavy coating.
In very polluted conditions, total algae biomass
is quite low, and the planktonic diatom community
missing. In case of functional complementary
however, it is possible that phytoplankton
and zooplankton mass remains stable.
==== Macroorganisms ====
Water insect and crustacean communities are
modified around a mine, resulting in a low
trophic completeness and their community being
dominated by predators. However, biodiversity
of macroinvertebrates can remain high, if
sensitive species are replaced with tolerant
ones. When diversity within the area is reduced,
there is sometimes no effect of stream contamination
on abundance or biomass, suggesting that tolerant
species fulfilling the same function take
the place of sensible species in polluted
sites. pH diminution in addition to elevated
metal concentration can also have adverse
effects on macroinvertebrates' behaviour,
showing that direct toxicity is not the only
issue. Fish can also be affected by pH, temperature
variations, and chemical concentrations.
=== Terrestrial organisms ===
==== Vegetation ====
Soil texture and water content can be greatly
modified in disturbed sites, leading to plants
community changes in the area. Most of the
plants have a low concentration tolerance
for metals in the soil, but sensitivity differs
among species. Grass diversity and total coverage
is less affected by high contaminant concentration
than forbs and shrubs. Mine waste-materials
rejects or traces due to mining activity can
be found in the vicinity of the mine, sometimes
pretty far away from the source. Established
plants cannot move away from perturbations,
and will eventually die if their habitat is
contaminated by heavy metals or metalloids
at a concentration that is too elevated for
their physiology. Some species are more resistant
and will survive these levels, and some non-native
species that can tolerate these concentrations
in the soil, will migrate in the surrounding
lands of the mine to occupy the ecological
niche.
Plants can be affected through direct poisoning,
for example arsenic soil content reduces bryophyte
diversity. Soil acidification through pH diminution
by chemical contamination can also lead to
a diminished species number. Contaminants
can modify or disturb microorganisms, thus
modifying nutrient availability, causing a
loss of vegetation in the area. Some tree
roots divert away from deeper soil layers
in order to avoid the contaminated zone, therefore
lacking anchorage within the deep soil layers,
resulting in the potential uprooting by the
wind when their height and shoot weight increase.
In general, root exploration is reduced in
contaminated areas compared to non-polluted
ones. Plant species diversity will remain
lower in reclaimed habitats than in undisturbed
areas.Cultivated crops might be a problem
near mines. Most crops can grow on weakly
contaminated sites, but yield is generally
lower than it would have been in regular growing
conditions. Plants also tend to accumulate
heavy metals in their aerian organs, possibly
leading to human intake through fruits and
vegetables. Regular consumption of contaminated
crops might lead to health problems caused
by long-term metal exposure. Cigarettes made
from tobacco growing on contaminated sites
might also possibly have adverse effects on
human population, as tobacco tends to accumulate
cadmium and zinc in its leaves.
==== Animals ====
Habitat destruction is one of the main issues
of mining activity. Huge areas of natural
habitat are destroyed during mine construction
and exploitation, forcing animals to leave
the site. Animals can be poisoned directly
by mine products and residuals. Bioaccumulation
in the plants or the smaller organisms they
eat can also lead to poisoning: horses, goats
and sheep are exposed in certain areas to
potentially toxic concentration of copper
and lead in grass. There are fewer ant species
in soil containing high copper levels, in
the vicinity of a copper mine. If fewer ants
are found, chances are higher that other organisms
living in the surrounding landscape are strongly
affected by the high copper levels as well.
Ants have good judgement whether an area is
habitual as they live directly in the soil
and are thus pretty sensitive to environmental
disruptions.
==== Microorganisms ====
Microorganisms are extremely sensitive to
environmental modification, such as modified
pH, temperature changes or chemical concentrations
do to their size. For example, the presence
of arsenic and antimony in soils have led
to diminution in total soil bacteria. Much
like waters sensitivity, a small change in
the soil pH can provoke the remobilization
of contaminants, in addition to the direct
impact on pH-sensitive organisms.
Microorganisms have a wide variety of genes
among their total population, so there is
a greater chance of survival of the species
due to the resistance or tolerance genes in
that some colonies possess, as long as modifications
are not too extreme. Nevertheless, survival
in these conditions will imply a big loss
of gene diversity, resulting in a reduced
potential for adaptations to subsequent changes.
Undeveloped soil in heavy metal contaminated
areas could be a sign of reduced activity
by soils microfauna and microflora, indicating
a reduced number of individuals or diminished
activity. Twenty years after disturbance,
even in rehabilitation area, microbial biomass
is still greatly reduced compared to undisturbed
habitat.Arbuscular mycorrhiza fungi are especially
sensitive to the presence of chemicals, and
the soil is sometimes so disturbed that they
are no longer able to associate with root
plants. However, some fungi possess contaminant
accumulation capacity and soil cleaning ability
by changing the biodisponibility of pollutants,
this can protect plants from potential damages
that could be caused by chemicals. Their presence
in contaminated sites could prevent loss of
biodiversity due to mine-waste contamination,
or allow for bioremediation, the removal of
undesired chemicals from contaminated soils.
On the contrary, some microbes can deteriorate
the environment: which can lead to elevated
SO4 in the water and can also increase microbial
production of hydrogen sulfide, a toxin for
many aquatic plants and organisms.
=== Waste ===
==== Tailings ====
Mining processes produce an excess of waste
materials known as tailings. The materials
that are left over after are a result of separating
the valuable fraction from the uneconomic
fraction of ore. These large amounts of waste
are a mixture of water, sand, clay, and residual
bitumen. Tailings are commonly stored in tailings
ponds made from naturally existing valleys
or large engineered dams and dyke systems.
Tailings ponds can remain part of an active
mine operation for 30-40 years. This allows
for tailings deposits to settle, or for storage
and water recycling. Tailings have great potential
to damage the environment by releasing toxic
metals by acid mine drainage or by damaging
aquatic wildlife , these both require constant
monitoring and treatment of water passing
through the dam. However the greatest danger
of tailings ponds is dam failure. Tailings
ponds are typically formed by locally derived
fills (soil, coarse waste, or overburden from
mining operations and tailings) and the dam
walls are often built up on to sustain greater
amounts of tailings. The lack of regulation
for design criteria of the tailings ponds
are what put the environment at risk for flooding
from the tailings ponds.
==== Spoil Tip ====
A spoil tip is a pile of accumulated overburden
that was removed from a mine site during the
extraction of coal or ore. These waste materials
are composed of ordinary soil and rocks, with
the potential to be contaminated with chemical
waster. Spoil is much different from tailings,
as it is processed material that remains after
the valuable components have been extracted
from ore. Spoil tip combustion can happen
fairly commonly as, older spoil tips tend
to be loose and tip over the edge of a pile.
As spoil is mainly composed of carbonaceous
material that is highly combustible, it can
be accidentally ignited by the lighting fire
or the tipping of hot ashes. Spoil tips can
often catch fire and be left burning underground
or within the spoil piles for many years.
=== Effects of mine pollution on humans ===
Humans are also affected by mining. There
are many diseases that can come from the pollutants
that are released into the air and water during
the mining process. For example, during smelting
operations large quantities of air pollutants,
such as the suspended particulate matter,
SOx, arsenic particles and cadmium, are emitted.
Metals are usually emitted into the air as
particulates as well.
There are also many occupational health hazards
that miners face. Most of miners suffer from
various respiratory and skin diseases such
as asbestosis, silicosis, or black lung disease.
=== Coal mining ===
=== Deforestation ===
With open cast mining the overburden, which
may be covered in forest, must be removed
before the mining can commence. Although the
deforestation due to mining may be small compared
to the total amount it may lead to species
extinction if there is a high level of local
endemism.
=== Oil shale ===
=== 
Mountaintop removal mining ===
=== 
Sand mining ===
Sand mining and gravel mining creates large
pits and fissures in the earth's surface.
At times, mining can extend so deeply that
it affects ground water, springs, underground
wells, and the water table.
== Mitigation ==
To ensure completion of reclamation, or restoring
mine land for future use, many governments
and regulatory authorities around the world
require that mining companies post a bond
to be held in escrow until productivity of
reclaimed land has been convincingly demonstrated,
although if cleanup procedures are more expensive
than the size of the bond, the bond may simply
be abandoned. Since 1978 the mining industry
has reclaimed more than 2 million acres (8,000
km²) of land in the United States alone.
This reclaimed land has renewed vegetation
and wildlife in previous mining lands and
can even be used for farming and ranching.
== Specific sites ==
Tui mine in New Zealand
Stockton mine in New Zealand
Northland Pyrite Mine in Temagami, Ontario,
Canada
Sherman Mine in Temagami, Ontario, Canada
Ok Tedi Mine in Western Province, Papua New
Guinea
The Berkeley Pit
Wheal Jane Mines
== 
Film and literature ==
Burning the Future: Coal in America
Coal River
Mountain Top Removal
Moving Mountains: How One Woman and Her Community
Won Justice From Big Coal
Tar Creek
Trou story
== See also ==
Environmental impact of deep sea mining
Environmental effects of placer mining
Environmental impact of gold mining
Environmental impact of zinc mining
List of environmental issues
Appalachian Voices, a lobby group in the United
States
