Meghan Hodges
Gold is a chemical element with the symbol Au and atomic number 79. It is a dense, soft, malleable, and ductile metal. Gold mining, however, has been associated with hazardous pollution, particularly the release of toxic heavy metals into the environment. The use of mercury in gold mining has led to a global health and environmental crisis, with mercury being a toxic substance that affects both miners' health and the planet. Gold mining has also resulted in the destruction of vast quantities of land and water pollution, with companies dumping toxic waste into natural water bodies. The environmental impact of gold mining has been the subject of studies and campaigns, with efforts to reduce destructive practices and promote recycled gold.
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What You'll Learn
Mercury pollution from gold mines
Mercury is a liquid metal that has been used for centuries as an inexpensive and easy way to collect gold. Mercury is mixed with ores dug from the ground or stream beds to form an amalgam, which is then burned to vaporize the mercury and leave the gold behind. This method is still used today by artisanal and small-scale gold mining (ASGM) operations. For every gram of gold produced, these miners release about two grams of mercury into the environment, contributing to about 35% of man-made mercury pollution. ASGM is the second-largest source of atmospheric mercury pollution after coal combustion.
Mercury is a highly toxic substance that wreaks havoc on miners' health and the environment. When released into the atmosphere or when it reaches rivers, lakes, and oceans, mercury can travel across great distances. It can contaminate water, air, and soil, and microbes in the environment can transform it into methylmercury, a potent neurotoxin that is harmful to humans and wildlife. Methylmercury can be taken up by bacteria, plankton, and other microorganisms that are then consumed by fish, building up to dangerous concentrations in animals higher on the food chain.
Communities downstream of mining activity have been found to have abnormal and alarming levels of mercury in their bodies. In Bolivia, for example, more than 1,000 artisanal mining operations are razing trees, diverting waterways, and reshaping the land in their search for gold. The Minamata Convention is a global treaty to protect human health and the environment from the effects of mercury, and while Bolivia's attorney general has defended the country's adherence to this convention, little has changed in remote mining camps.
Technologies exist that can prevent mercury pollution by reducing the quantity used and then recycling it. For example, miners can concentrate the gold as much as possible before adding mercury, then heat the amalgam in a closed system that captures and reliquefies the mercury for reuse. In addition, the EPA and ANL have developed a Mercury Capture System (MCS) that is highly effective, inexpensive, and easy to construct using locally available materials. While complete elimination of mercury from the ASGM process is desirable, significant emissions reductions can be achieved in the near term by capturing mercury during amalgam burns.
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Gold mining and heavy metal pollution
Gold mining has various environmental impacts, including the release of toxic contaminants that harm the ecosystem and human health. One of the significant issues associated with gold mining is heavy metal pollution, which occurs through several processes and has far-reaching consequences.
Gold mining activities generate large quantities of heavy metal-laden wastes, which are often released in an uncontrolled manner. This release leads to widespread contamination of the ecosystem, affecting both the environment and human health. The heavy metals found in these wastes, such as manganese (Mn), aluminium (Al), nickel (Ni), iron (Fe), chromium (Cr), and vanadium (V), can have detrimental effects on the natural population of bacteria in the soils. This disruption in bacterial diversity impacts nutrient cycling and ecosystem functioning.
Tailings, the major wastes produced from gold extraction, contain high amounts of heavy metals. When exposed to water or dispersed by wind, these heavy metals leach into the surrounding environment. This leaching process results in acid mine drainage (AMD), a severe environmental concern. AMD occurs when underground rock disturbed by mining is exposed to air and water, causing iron sulfides ("fool's gold") to react with oxygen and form sulfuric acid. This acidic water can be highly concentrated and toxic to living organisms, and it further strips out embedded heavy metals as it runs over rocks. As a result, rivers and streams become contaminated with metals such as cadmium, arsenic, lead, and iron, which have been linked to various health issues, including liver disease and learning disabilities in children.
The use of mercury in gold mining is another significant contributor to heavy metal pollution. Mercury is a toxic liquid metal used in artisanal and small-scale gold mining to extract gold from rock and sediment. For every gram of gold produced, artisanal gold miners release about two grams of mercury into the environment. Mercury enters the atmosphere and reaches water bodies, travelling across great distances. Mercury amalgamation, where mercury is mixed with ores and burned to vaporize and separate the gold, is a leading cause of global mercury pollution.
Gold mining practices, such as open-pit mining and cyanide heap leaching, also contribute to the release of toxic heavy metals. Mining companies generate significant amounts of toxic sludge containing cyanide and heavy metals, which are often dumped directly into natural water bodies. This dumping destroys aquatic life and contaminates water sources.
Overall, gold mining and heavy metal pollution are closely interconnected, with mining activities releasing toxic heavy metals into the environment and causing widespread ecological and human health issues.
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Gold mining's impact on water pollution
Gold mining affects water pollution in several ways. Firstly, it requires a heavy use of water in processing ore, which can impact local water sources. Secondly, gold mining generates large quantities of waste rock and tailings, which can contaminate water through seepage and discharged mine effluent. Tailings are the major wastes produced from gold extraction and they contain high amounts of heavy metals, which can leach out into the surrounding environment when exposed to water. This can result in heavy metal pollution of waterways, with metals such as arsenic, cobalt, copper, cadmium, lead, silver, and zinc contaminating rivers and streams.
The use of mercury in gold mining is also a significant source of water pollution. Mercury is a toxic substance that is used to extract gold from rock and sediment. For every gram of gold produced, artisanal gold miners release about two grams of mercury into the environment. Mercury enters rivers, lakes, and oceans, and can travel across great distances, contributing to global mercury pollution.
Another issue is acid mine drainage, which occurs when underground rock disturbed by mining is exposed to air and water, forming sulfuric acid. This acidic water can be highly toxic to living organisms and can contaminate rivers and streams with heavy metals.
The impact of gold mining on water pollution can be long-lasting, with pollution from mine waste and tailings needing to be managed for decades or even centuries after a mine has closed. The development of more mechanized mining technologies has also increased the amount of waste generated, further exacerbating the problem.
Overall, gold mining has a significant impact on water pollution, with potential consequences for both the environment and human health.
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Gold mining's impact on land destruction
Gold mining has been identified as one of the most destructive industries in the world, with far-reaching negative impacts on people and the planet. One of the most significant ways gold mining contributes to land destruction is through the generation of vast quantities of toxic waste. For instance, modern industrial gold mining techniques can produce about 20 tons of toxic waste for every 0.333-ounce gold ring. This waste is often in the form of a grey liquid sludge, containing deadly cyanide and toxic heavy metals.
Gold mining companies dump at least 180 million tons of this toxic waste into rivers, lakes, and oceans each year, destroying aquatic life and contaminating drinking water. For example, the Lihir gold mine in Papua New Guinea dumps over 5 million tons of toxic waste into the Pacific Ocean annually, wreaking havoc on corals and other ocean life. Even when toxic waste is not directly dumped into natural water bodies, it can still contaminate waterways when infrastructure such as tailings dams fail.
The process of gold mining can also lead to a persistent problem known as acid mine drainage. This occurs when underground rock disturbed by mining is newly exposed to air and water. Iron sulfides (often called "fool's gold") in the rock react with oxygen to form sulfuric acid. This acidic water is highly toxic to living organisms and can be 20 to 300 times more concentrated than acid rain. When this acidic water runs over rocks, it can strip out other embedded heavy metals, further contaminating rivers and streams.
The use of mercury in gold mining is another major contributor to land destruction. Mercury is a toxic substance that is used to extract gold from rock and sediment. For every gram of gold produced, artisanal gold miners release about two grams of mercury into the environment. These mercury emissions can travel across great distances, contaminating land and water sources. Mercury is the second-largest source of atmospheric mercury pollution after coal combustion, and it poses significant risks to human health and the environment.
In addition to the direct ecological consequences, gold mining can also have indirect effects on the land through the destruction of landscapes and vegetation. Large-scale mining operations can result in the deletion of massive amounts of surface vegetation, affecting biodiversity and causing soil erosion and land degradation. Furthermore, mining activities can negatively impact local communities by displacing them and disrupting roads and other services in the area.
The environmental impacts of gold mining are long-lasting and challenging to mitigate. While some natural recovery processes occur, such as bacteria developing ways to withstand high concentrations of heavy metals, the overall effect is a significant and persistent disruption to ecosystems.
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Gold mining's impact on human health
Gold mining can have detrimental effects on human health, and several issues have been observed in communities near gold mines. Mining can pollute the environment with toxic heavy metals and generate large amounts of waste, which can then enter the food chain and cause various health problems.
One of the most significant issues associated with gold mining is the use of cyanide and mercury to extract gold from ore, rock, or sediment. Cyanide leaching uses large quantities of cyanide to separate gold from crushed rock. Cyanide is lethal to humans in very small amounts, and there have been several cyanide spills and accidents. These spills can contaminate water sources, posing a significant risk to human health. Mercury, a toxic liquid metal, is also often used in artisanal and small-scale gold mining. For every gram of gold produced, about two grams of mercury are released into the environment. Mercury can travel long distances and pollute water bodies and the atmosphere. When burned, it forms a toxic plume, and mercury pollution has been linked to a range of health issues.
The waste generated by gold mining often contains high concentrations of toxic heavy metals, including cadmium, lead, arsenic, and iron. These metals can contaminate water sources, leading to health issues such as liver disease (from cadmium), skin cancer and tumours (from arsenic), and learning disabilities and impaired development in children (from lead). High concentrations of heavy metals have also been found in plant species near gold mines, which can then enter the food chain. Additionally, the destruction of landscapes and ecosystems caused by mining can have indirect effects on human health, such as the destruction of crop plants and the loss of nutrient cycling due to disruptions in bacterial populations.
The specific health impacts of gold mining on local communities have been observed in several regions. For example, in Montana, health problems such as asthma, emphysema, thyroid problems, and diabetes have been on the rise, especially among children, in areas near gold mines. Similarly, the Fort Belknap Indian Reservation has experienced health and environmental concerns potentially related to water pollution from cyanide heap leach gold mining.
Overall, gold mining can have severe impacts on human health, and proper regulations and waste management practices are necessary to mitigate these effects.
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Frequently asked questions
Gold is not a natural pollutant. However, the process of mining gold is often linked to environmental disasters and hazardous pollution.
Gold mining often involves the use of toxic chemicals such as mercury and cyanide, which can contaminate the surrounding land, water, and air. For example, mercury is used to form an amalgam with gold, and burning this amalgam releases toxic mercury vapors into the atmosphere. Additionally, mining activities generate large amounts of heavy metal-laden waste, which can leach into the environment through water or wind, causing widespread ecosystem contamination.
Gold mining has been associated with the destruction of landscapes, the release of toxic waste, and water pollution. It can result in the dumping of millions of tons of waste into natural water bodies, destroying aquatic life and coral reefs. The toxic and acidic water produced by mining activities can be lethal to wildlife and pose risks to human health if it contaminates drinking water sources.
Efforts to reduce the environmental impact of gold mining include the promotion of recycled gold, the development of "golden rules" to encourage responsible mining practices, and the use of alternative extraction methods that minimize the use of toxic chemicals.
