Mining is one of the oldest industries and extracts solid materials and minerals necessary to produce many of the modern products in everyday life. However, it has environmental impacts felt beyond mines and their vicinity.
Land Affected by Mining
A study published in 2012 in the Geological Society of America estimated that 0.3% of global land is affected by mining. They summarize this amounts to around 0.4 million square kilometers. The U.S. is a major mining nation and is ranked seventh in mined metal production in the world with an output valued at $32 billion according to the 2016 National Mining Association report (pg. 17), so large areas of mined land lie here.
There are many forms of mining depending on the resource being extracted. Each of these methods have varying impacts on the environment. American Goesciences Institute explains there are four types of mining:
- Underground mining that involve digging and tunneling to reach deep deposits like coal according to Greenpeace.
- Surface or strip mining removes surface vegetation and soil to exploit shallow deposits of coal.
- Placer mining extracts metals by sifting from river beds or beach sands. Gold is an example of a metal that is extracted this way notes Mongabay.
- In-situ recover or in-situ leaching mining is used for uranium extraction, points out New Mexico Bureau of Geology and Mineral Resources.
Some resources can be mined using more than one method, as in the case of coal, gold and uranium, and can then have many environmental impacts which include deforestation, destruction of habitats, soil erosion, disruption of watershed, and pollution.
Exploration, production or extraction and post-mining land-use are the three phases of mining according to National Academy Press (Steps), and are all processes which result in deforestation explains Global Forest Atlas (GFA). Many of the minerals are located in forests or in protected areas in the tropics and boreal. For example, mining is responsible for,
- Seven-hundred fifty-thousand hectares of Canadian boreal forests have been lost since 2000 due to tar sand production adds GFA.
- In Brazil, mining for copper, iron ore, manganese and gold, as well as production of charcoal to power iron plants results in a loss of 6,100 square kilometers of Amazon forests every year according to World Wide Fund For Nature (WWF).
- 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 is affected, but is favored by the industry as it is cheaper reports Greenpeace. So 40% of the world's coal is obtained by strip mining.
In the U.S., strip mining produced 66% of the coal in 2015, according to the U.S. Energy Information Administration (EIA); here it has involved blowing off mountain tops in the Appalachian Mountains in West Virginia and Kentucky. Greenpeace reports that since 1930 to 2000, "nearly 2.4 million hectares (5.9 million acres)" of forests and other natural habitats have been cleared in the U.S. due to strip mining.
Loss of forests and subsequent mining operations disturb the soil. Strip mining is particularly responsible for soil erosion as the top soil is blasted to reach the shallow seams of coal according to Greenpeace. 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 in many mined areas in the U.S., so former forested areas are reclaimed by planting grass which alone can survive in these conditions notes a study reported in Bioscience in 2013.
Massachusetts Institute of Technology (MIT) elaborate that the erosion effects can linger long after mining has ended, and can impact swathes of land, beyond the immediate surroundings of the mine. For example, metallic dust from copper and nickel mines persist for many decades and reach areas 2-3 kilometers away from mines points out a 2014 University of Minnesota Center for Forest Ecology report (pg. 7).
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, and there are 500,000 abandoned mines waiting to be cleaned and reclaimed in the whole country.
Surface or open pit mining and underground mining are hazardous in all stages of mining. Soil waste dug and tunnelled is left as tailings or spoils, and can expose radioactive rocks, and create metallic dust. These tailings are also subject to erosion by wind and rain. When mixed with water the toxic soil brought up forms slurry which can soak into soil or leach into water explains MIT.
Metals when they mix with water can also become acidic. This acid drainage can be a major environmental and health problem that persists for centuries notes Greenpeace and National Geographic. In Tar Creek, Oklahoma, zinc and lead that found its way into water, has made drinking water unsafe for local communities adds National Geographic.
Copper and nickel dust from mines can make soil acidic for many kilometers of land around mines, and affect plant growth and animals reports the 2014 University of Minnesota report.
Many of the chemicals used in mining are toxic and can escape into soil and water too. Mercury used in underground and hydraulic mining for gold causes water pollution affecting aquatic life note WWF and Mongabay. Cyanide is another toxic chemical used in mining that can collect in leach ponds harming wildlife drinking from them points out MIT.
Dust is a major air pollutant produced by mining. Fine and coarse particulate matter (PM) that measure less than 2.5 μm to 10 μm are the problem here. Fine PM is a greater problem as it can reach the lungs leading to respiratory problems. Visibility can also be affected in times of acute dust plume production explains an Australian government release.
The process of mining can increase climate change risks. For example methane gas that is trapped in coal seams is released into the air in underground mining. The EIA estimates that in 2014, coal mining was responsible for 10% of the total methane production in the U.S.. Since this is one of the greenhouse gases, its release increases global warming. Moreover, deforestation destroys erstwhile carbon sinks increasing carbon dioxide levels in the atmosphere.
Depletion of Ground and Surface Water Sources
Mining depletes ground and surface water through many ways, and can in many cases also pollute it affecting its quality.
Reduction of Watershed Area
One of the ways ground water is depleted is by reducing the watershed area by cutting forests. Forest trees break the fall of rain, and help in its slow absorption by the soil. This water then seeps down into the soil to recharge the ground water reservoirs or rivers. When there is less forests, there is less ground or river water recharged, and is lost as runoff. WWF, Borneo considers these watersheds crucial for the rivers of the islands.
Strip mining and underground mining both pump ground-water from reservoirs reducing water for alternate uses like farming or drinking for local communities points out Greenpeace. For example in Germany 500 million cubic meters of water is removed by the mining industry each year and most of which goes waste.
Stream Flow Blocked
Wilkes University reports that the soil from mountain strip mining fills valleys. In many cases these have blocked streams, so that downstream rivers have dried up. Blockage of streams and dumping soil has led to drying and destroying entire wetlands and swamps which used to absorb and retain rainwater. In addition artificial pit pools and sedimentation lagoons containing water contaminated by the toxic chemicals in mines are produced that are ecological unproductive.
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, and the effect depends on the type of mining and materials mined.
The 2014 University of Minnesota report illustrates how mining can affect habitats due to forest loss and degradation.
- 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 forest species. It can take decades to many centuries before the previous rich and diverse forest community can grow back (pg. 2).
- Forest fragmentation: 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 results in many other harmful effects. There is more sunlight in the edges and they are warmer. In these different conditions it is the more weedy plant and tree species that grow here. The more sensitive forest species of trees and associated animals disappear from edges (pg. 3).
- Invasive species: In the empty mines and the forest edges, invasive species can take hold and spread so more area for forest species is lost (pg. 3).
- Wildlife habitats are lost: Loss of trees leads to loss of nesting places for birds, and mammals like foxes and wolves do not like to den near places with people and these species move away from mines. Many birds and animals require a large territory of undisturbed forest to survive, and fragmentation by mines disrupts their movement and sometimes even migration decreasing their numbers and diversity in the mines and surrounding areas (pg. 4, 5).
- Pollution: Noise and light pollution affect many songbirds; and acid dust pollution from the mines affects amphibians like salamander and frogs sensitive to pH (pg. 5).
- Rare species: Populations of rare tree species can be cut down in mines reducing their overall numbers in the forests, making them susceptible to local extinction (pg. 5).
- Road deaths: Roads connecting mines lead to animals death due to accidents (pg. 1).
- Increased hunting: Once constructed roads also facilitate increased hunting of wild animals. Pangolin, orangutan, and other species have been decreasing in Borneo due to roads according to a WWF report on Borneo.
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 in 2013.
- Niches lost: This also simplifies the landscape, and in addition to disturbed soil, 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, points out the 2013 Bioscience study.
- Temperatures rise: When the elevation of mountains are lowered, the mountain tips that are colder regions are lost. Mountain top mines have been found to be warmer than surrouding mountain tops, says the 2013 Bioscience study.
- Loss of forest areas: Since it has been difficult to grow trees in many mined areas in the U.S. due to to pollution of the soil, 70% of former forested areas are lost replaced by grasslands changing and reducing biodiversity considerably points out the 2013 Bioscience study.
- Wetland and swamps diversity is lost: When soil dumped in streams block water movement, wetlands and swamps that are normally formed in lower areas dry up. Different areas support different sets of plants and there are many special groups of animals and birds that are associated with them. With the loss of these entire habitats, the rich diversity of birds and other animals they normally supported is also lost, leaving the region with less biodiversity, notes Wilkes University.
Pollutants Kill Flora and Fauna
Mining releases dust and many chemicals into the atmosphere that pollutes air, water, and land.
- Habitat loss: 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, reducing the amount of watery habitat available for fish. So local fish populations decrease even if the waters are not toxic according to Mongabay.
- Mercury poisoning: In many cases, like gold mining, toxic chemicals like mercury used in extraction poison the surrounding areas killing fish and reducing their populations. People who consume them also have serious health problems report Phys.org, because mercury disturbs the functioning of vital organs. Mongabay notes that small scale miners who are less efficient can use and release "2.91 pounds (1.32 kg) of mercury into waterways for every 2.2 pounds (1 kg) of gold produced". GFA reports that one-third of mercury contamination in the world is due to gold mining.
- Selenium toxicity: Mountain mines cause release of 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. This rare element can be absorbed by water plants and when smaller aquatic life eat them, the amount of selenium accumulates in their body tissues in concentrations higher than that in plants. Large animals eating the smaller animals will accumulate more concentrations of the element. This is called bioaccumulation and high concentrations of selenium cause reduced births and therefore numbers of macroinvertebrates in the streams according to the 2013 Bioscience study.
Health Risks to Miners and Local Communities
Miners and local communities can suffer health risks due to mining.
Occupational Hazards of Mining
The Union of Concerned Scientists reports that underground mining has many occupational hazards. Miners can be injured or killed when the mine roof or tunnels collapse, and it causes chronic health problems. These problems can sometimes be fatal reports Live Science, as miners are continuously exposed to dust, toxic chemicals and fumes, and heavy metals. Mining was regarded as the most dangerous industry till 2001. New technology and safety procedures have improved working conditions, and by 2009 the number of deaths were reduced to 34 per year. The number of injuries have been halved to that which occurred thirty years earlier.
The health problems for miners can be cancers and respiratory diseases reports International Institute for Environment and Development (pg. 7, 8). There can also be specific health effects from different metals mined. Materials those are hazardous like coal, asbestos and uranium are the ones which have the most impact on miners.
Community Health Around Mines
Similarly, the effects on communities depends on the metals mined as well the pollutants that are released.
- For example, people living close to mountain strip mines have more birth defects, higher rates of lung, respiratory and kidney problems.
- Moreover, groundwater contaminated by arsenic leads to many health impacts including possible cardiovascular diseases according to the 2014 University of Minnesota Report.
- National Geographic reports occurrence of bone cancer and kidney problems in the Navajo National Land due to water contamination by radionuclides (or radio-active isotopes) due to uranium mines.
Threat to Indigenous Communities
Indigenous communities have lived in harmony in forests for thousands of years. Mining is one of the main reasons why they are displaced worldwide.
- GFA reports that in the Amazon alone, 8% their land is threatened by concessions given to mining communities.
- In the U.S., there are 15,000 abandoned uranium mines, 75% of which are located on "Federal and Tribal Lands" according to Global Research. The Environmental Protection Agency notes that 30 million tons of uranium ore were extracted from Navajo lands between 1944 to 1986, and only 94 of the abandoned mines were being cleaned and reclaimed by 2017.
- Many indigenous peoples in Australia are resisting new mines due to the environmental and health impact of old mines according to The Conversation.
Reduce the Need to Mine
Without mined materials like fossil fuels, metal-ore, precious metals, and other mined resources, modern life would be impossible, as National Academy Press points out. Therefore mining will remain part of the economy. Modern technology is being used to reduce environment impacts. Another way to limit environmental impact is to decrease the amount of mining undertaken. Individuals can help by recycling to reduce demand for the minerals and metals, and by reducing reliance on fossil fuels. By controlling the extent of mining, its effects can be reduced, and these precious and limited non-renewable resources can also be spared for future generations.