Mining is one of the oldest industries to extract solid materials and minerals necessary to produce many of the modern products in every day life. However, it has environmental impacts felt beyond mines and their vicinity.
How Mining Methods Affect the Environment
There are many forms of mining depending on the resource being extracted. Each of these methods create types of pollution.
- Underground mining involves digging and tunneling to reach deep deposits like coal.
- Surface or strip mining removes surface vegetation and soil to exploit shallow deposits of coal.
- Placer (extracting) mining of metals is done by sifting riverbeds or beach sands. Gold is an example of a metal that is extracted this way.
- In-situ (original place) recover or in-situ leaching mining is used for uranium extraction.
Employing Multiple Mining Methods
Some resources can be mined using more than one method, as in the case of coal, gold and uranium. These methods can also have environmental impacts, such as deforestation, destruction of habitats, soil erosion, disruption of watershed, and pollution.
The three mining phases are exploration, production or extraction and post-mining land-use. All processes result in deforestation. Many of the minerals are found in forests or in protected areas in the tropics and Canada's Boreal Forest.
For example, mining is responsible for:
- According to Global Forest Atlas (GFA), 7% of subtropics deforestation is due to extraction of oil, minerals and gas.
- 750,000 hectares of the Canadian boreal forests have been lost since 2000 due to tar sand production (low quality oil strip mined or extracted with high pressure steam injection).
- 60% of the Amazon rainforest is located in Brazil. According to Mongabay (U.S.-based environmental science news), deforestation in Brazil began to decline in 2004 and since that time has reached an 80% drop. However, in 2019, wildfires attributed to the highest levels of deforestation since the decline.
- Release of mining wastes can also affect habitats. For example, 10,000 hectares of forests were lost through die-off as a result of copper mine wastes in Papua New Guinea according to GFA.
- The type of mining and the material mined also has an important influence on the extent and type of destruction. Consider the example of coal extraction through strip mining.
Strip Mining of Coal
Coal is mined by strip and underground mining. Strip mining is more harmful as larger tracts of land are affected but is favored by the industry as it is cheaper. 40% of the world's coal is obtained by strip mining.
Surface Mining in United States
According to the U.S. Energy Information Administration (EIA) in 2018, 63% of the U.S. coal production came from surface mines. Surface mining includes strip mining, mountaintop removal mining and open-pit mining.
Loss of forests and subsequent mining operations disturb the soil. Strip mining is particularly responsible for soil erosion as the topsoil is blasted to reach the shallow seams of coal in mountain top mining.
Environmental Devastation From Topsoil Loss
The displaced fertile topsoil is eroded or transported away, leaving the area unfit for growing any trees. It is this disturbance of soil which makes it difficult to grow trees.
Linger Environmental Effect of Mining Erosion
According to Massachusetts Institute of Technology (MIT) the effects of mining erosion can linger long after the mining has ended. Large swathes of land are impacted, beyond the immediate surroundings of the mine. The University of Minnesota Center for Forest Ecology reports that metallic dust from copper and nickel mines often persist for many decades and can even reach areas 2-3 miles away from the actual mines points out.
Pollutants Buried in Soil Are Released
There are many heavy metals and toxic chemicals that are buried in the soil that get released during mining and end up polluting air, water and land. National Geographic reports that 40% of the watershed in western U.S. are affected by mining pollutants. Many watersheds in the U.S. are also polluted from runoff of mines in Canada.
Cleaning Up Contaminated Waters
Over 500,000 abandoned mines in the U.S. are waiting to be cleaned and reclaimed. In 2019, the Cheat River in West Virginia was declared "clean" after decades of running orange due to acid mine pollution.
Mine Tailings from Ore Mines
Surface or open pit mining and underground mining create mine tailings that are often in the form of a mud-like or slurry substance. The tailings from digging and tunneling are soaked up by the soil and can leach into the water.
Hazardous Radioactive Rocks Exposed
The mining process can also expose radioactive rocks and create metallic dust. However, stockpiles of waste rock aren't easily absorbed by water and soil since the particles are too dense, unlike the dust thrown into the atmosphere from mining operations.
When metals mix with water, the water can become acidic. This acid drainage can be a major environmental and health problem that persists for centuries.
Copper and nickel dust from mines can make soil acidic for many kilometers of land around mines. The acidic soil affects plant growth and animals.
Many of the chemicals used in mining are toxic and can escape into soil and water. For example, mercury used in underground and hydraulic mining for gold causes water pollution that negatively affects aquatic life. Cyanide is another toxic chemical used in mining that can collect and leach into ponds harming wildlife.
Harmful Mining Dust Particles
Dust is a major air pollutant produced by mining. Fine and coarse particulate matter (PM) that measure less than 2.5 pm to 10 pm are the problem here. Fine PM is a greater threat since it can reach the lungs leading to respiratory problems. Visibility can also be affected in times of acute dust plume production.
Coal Mine Methane Gas Release
The process of mining can release methane gas that is trapped in coal seams. The methane gas is released into the air in underground mining. The EPA attributes 8.5% of methane emissions in the United States to Coal Mine Methane (CMM).
Depletion of Ground and Surface Water Sources
Mining depletes ground and surface water. Some of the ways mining pollutants affect water is through reducing the watershed areas.
Reduction of Watershed Area
Ground water is depleted through mining operations from cutting forests. The forest trees break the fall of rain and slows the absorption rate in the soil. The water then seeps down into the soil to recharge the groundwater reservoirs or rivers. When there are fewer forests, there is less ground or river water recharged, Water is lost through runoff.
In strip mining and underground mining, the groundwater is pumped from reservoirs. This process reduces the amount of water available for farming and as drinking water for local communities.
Stream Flow Blocked
In many cases, strip mining blocks streams, causing downstream rivers to dry up. Blockage of streams and the dumping of mining soil has led to the destruction of entire wetlands and swamps that previously absorbed and retained rainwater.
Mining Ponds and Sedimentation Lagoons
Artificial pit pools and sedimentation lagoons are built to contain water contaminated by the toxic chemicals from the mines. These waste water reservoirs are ecologically unproductive and dredging techniques are required to clean up these mining ponds.
Habitat Loss and Alteration
Habitat loss can occur due to mining through many ways. Deforestation, downstream silt accumulation, and contamination by toxic chemicals are some of the important causes of habitat loss. The effect depends on the type of mining and materials mined.
Mining can affect habitats due to forest loss and degradation. This includes loss of biodiversity, forest fragmentation and other environmental problems.
Loss of Biodiversity
When pristine old forest growth is cut down, the plants and species that grow on the empty land are common hardy species instead of the forest species. It can take decades to many centuries before the previous rich and diverse forest community grows back.
Forests cleared to make way for mines create empty gaps or stretches that break up previously continuous forests into small fragments. This is called fragmentation, and besides the loss of the trees there are many other harmful effects, such as more sunlight and warmer temperatures. In these new conditions, more weedy plant and tree species begin to grow. The more sensitive forest species of trees and associated animals disappear.
In the empty mines and the forest edges, invasive species can move in. These species take up residence and spread into more of the forest, displacing or eliminating the previous forest species.
Lost Wildlife Habitats
The loss of trees leads to a loss of nesting places for birds. Mammals like foxes and wolves don't like to den near places with people, so these species move away from mines. Many birds and animals require a large territory of undisturbed forest to survive. Forest fragmentation by mines disrupts their movement and can even force migration that further decreases the wildlife diversity surrounding the mines.
Noise and Light Pollution
Noise and light pollution affect many songbirds, driving them to search for new habitats. Acid dust pollution from the mines affects amphibians, such as salamanders and frogs that are sensitive to pH levels.
Populations of rare tree species cut to make room for mining operations are at risk. The creation of mines reduces the overall number of rare species in the forests, making them susceptible to local extinction.
Animal Road Deaths
With the construction of necessary roads to the mines, the loss of animal life increases. Animals deaths increase around mines from vehicles traveling the mining roads.
Increase in Hunting
Once roads are constructed to facilitate the mining operation, there is an increase in the hunting of wild animals as local hunters discover these new inroads to virgin hunting grounds. For example, in Borneo, the number of pangolin, orangutan, and other species are reported to be on the decline due to being killed by hunters who previously didn't venture into the areas.
Mountain Top Strip Mining
Strip mining has some specific effects. In addition to the general effects of mountain top strip mining, such as forest fragmentation, it's responsible for the disappearance of the rarer birds, mammals and reptiles.
Effects of Mountain Top Strip Mining
Strip mining has some effects peculiar to it in addition to the general effects of mining like fragmentation, disappearance of the rarer birds, mammals and reptiles according to research published in Bioscience.
Irreparable Landscape Changes
Landscapes are changed when the tops of mountains are removed, The area is flattened changing the type of landscapes forever.
Many small niches or living spaces for plants and animals are lost. When the types of living areas are reduced, there is less diversity of plants and animals.
When the elevation of mountains are lowered, previously colder regions are lost. Mountain top mines have been found to be warmer than surrounding mountain tops.
Loss of Forest Areas
Forest areas are lost due to mountain top mining. Since it is difficult to grow trees in many mined areas, lost forests are replaced by grasslands, which change and reduce the biodiversity of the area.
Wetlands and Swamp Diversity Lost
When soil from the excavated mountain top is dumped into streams, it blocks water movement. Wetlands and swamps dry up taking with them entire habitats of birds and animals.
Steps to Lessen Mountain Top Mining Impact on Environment
Yale School of Forestry & Environmental Studies developed a technique known as deep-ripping to break up the heavily compacted soil created from mountaintop mining. This technique uses three-foot steel blades that scores the earth to allow their projects of native tree plantings to take root.
Pollutants Kill Flora and Fauna
Mining releases dust and many chemicals into the atmosphere that pollutes air, water, and land. This can result in habitat loss and chemical poisoning.
Hydraulic mining for gold in tropical forests produces loose silt that increases sediment loads carried by the river and deposited downstream. This reduces water flow in these areas, including the amount of watery habitat available for fish. Local fish populations decrease even if the waters are not toxic.
Mercury, a toxic chemical, is often used in gold extraction. Mercury poisons the surrounding areas. Fish die from the poisoned waters, reducing their populations. According to Phys.org, people consuming mercury poisoned fish risk serious health problems since mercury disturbs the functioning of vital organs.
Mountain mines release selenium, which in large quantities can be toxic even to humans. There is 20 to 30 times more Selenium in streams affected by mountain mines than streams not affected by mines. This rare element can be absorbed by water plants and when smaller aquatic life eat them. Accumulated concentrations of selenium in fish are higher than what's found in plants.
Bioaccumulation in Animals From Mining
When larger animals eat smaller animals contaminated with a mine runoff poison, such as selenium, the larger animal will accumulate the concentration of the element. This is called bioaccumulation and high concentrations of selenium can cause reduced births and the number of macroinvertebrates in streams.
Health Risks to Miners and Local Communities
Miners and local communities can suffer health risks due to mining. The Union of Concerned Scientists reports that underground mining has many occupational hazards.
Occupational Hazards of Mining
Miners can be injured or killed when the mine roof or tunnels collapse, causing chronic health problems for survivors. These problems can sometimes be fatal reports, especially for miners continuously exposed to mineral dust, toxic chemicals/fumes, and heavy metals.
Mining Fatality Statistics
Mining was regarded as the most dangerous industry until 2001. New technology and safety procedures have improved working conditions. In 2018, mining related fatalities for the coal industry was 12 and 16 for the metal/nonmetal mining industry. These statistics include office workers. The number of injuries have been half to those that occurred thirty years earlier.
Health Issues for Miners
According to the International Institute for Environment and Development, miners face life-threatening health problems ranging from cancers to respiratory diseases. Miners are also at risk of specific health effects from various metals and hazardous materials, such as coal, asbestos and uranium.
Community Health in Areas With Mines
Similarly, the effects on communities depends on the metals mined. The various pollutants that are released can impact the health of those living near the mines. Examples of health risks include:
- People living close to mountain strip mines have more birth defects, higher rates of lung, respiratory and kidney problems.
- Groundwater contaminated by arsenic leads to many health problems, including possible cardiovascular diseases.
- The EPA (Environmental Protection Agency) reports occurrences of bone cancer and kidney problems in the Navajo National Land due to water contamination by radionuclides (or radio-active isotopes) from uranium mines.
Abandoned Uranium Mines
According to Global Research, 75% of the 15,000 abandoned uranium mines in the US are on Federal and Tribal Lands. The Environmental Protection Agency states between 1944 to 1986, 30 million tons of uranium ore were extracted from Navajo lands. The EPA further reports that of the 523 abandoned uranium mines on Navajo lands, funding has been released to cleanup 213 of them.
How Mining Demands Affect the Environment
Without mined materials like fossil fuels, metal-ore, precious metals, and other mined resources, modern life would be impossible. Many precious metals are used to create modern technologies making it difficult to get away from the demand for non-renewable resources, such as precious metals. However, by controlling the extent of mining and developing safe ways to manage mining waste, the environmental impact can be reduced.