Mining's Impact: Pollution And Environmental Consequences

Mining can have a significant impact on the environment and human health. It can cause soil erosion, loss of biodiversity, and contamination of soil, groundwater, and surface water by chemicals emitted as a result of mining processes. These processes also affect the atmosphere through carbon emissions, which contribute to climate change.

Mining operations are rigorous and intrusive, often resulting in significant environmental impacts on local ecosystems and broader implications for the planet's environmental health. The large amounts of water used in mining processes can increase the potential for chemicals to contaminate ground and surface water.

Mining can also affect human health, with miners often suffering from various respiratory and skin diseases. Additionally, the pollutants released into the air and water during the mining process can cause diseases in surrounding communities.

Water pollution

Water is essential to life on Earth, and it is a prerequisite of sustainable development to ensure that streams, rivers, lakes, and oceans remain uncontaminated. Mining, an everyday economic activity, has undeniable negative impacts on the environment, and particularly on waterways, from drinking water supplies to lakes and rivers.

There are four main types of water pollution caused by mining:

• Acid Mine Drainage (AMD): This is a process whereby sulphuric acid is produced when sulphides in rocks are exposed to air and water. When large quantities of rock containing sulphide minerals are excavated, it reacts with water and oxygen to create sulphuric acid. This acid is then carried off the mine site by rainwater or surface drainage and deposited into nearby water sources, including groundwater, lakes, rivers, and streams. AMD severely degrades water quality, and can kill aquatic life, as well as make water virtually unusable.
• Heavy Metal Contamination: Heavy metal pollution is caused when metals such as arsenic, cobalt, copper, cadmium, lead, silver, and zinc, which are contained in excavated rock or exposed in an underground mine, come into contact with water. Metals are leached out and carried downstream. Although metals can become mobile under neutral pH conditions, leaching is accelerated under low pH conditions, such as those created by AMD. Even trace amounts of heavy metals in water sources can pose serious health problems for humans and aquatic life, and the concentrations of these metals increase as they move up the food chain.
• Processing Chemicals Pollution: Mining companies use chemical compounds such as sulphuric acid or cyanide to separate target minerals from ore. When these chemicals spill, leak, or leach from the mine site into nearby water bodies, they can be highly toxic to humans and wildlife.
• Erosion and Sedimentation: Mining often involves the removal of earth and rocks, which leads to the destruction of agricultural lands and erosion of soil. When these sites experience heavy rain, the loosened topsoil is washed away, carrying sediments that may pollute streams, lakes, and rivers. Excessive residue can harm aquatic organisms and vegetation downstream, and it can also cause disfiguration of streams and river channels, resulting in flooding.

The impact of mining on water pollution can vary depending on several factors, including the sensitivity of the local terrain, the composition of the minerals being mined, the technology employed, and the company's skill, knowledge, and environmental commitment. While improvements have been made to mining practices in recent years, significant environmental risks remain, and the negative impacts of mining on water sources may need to be managed for decades, if not centuries, after a mine's closure.

Air pollution

Mining is a significant contributor to air pollution, which is a leading cause of environmental health issues globally. At every stage of the mining process, from ore extraction to waste generation and ore refining, air pollution is created, impacting both the environment and public health.

Sources of Air Pollution in Mining

Mobile Sources

Vehicles and machinery operating in and around mines release pollutants, with the type and amount of emissions depending on the fuel used and its maintenance conditions.

Stationary Sources

Stationary sources include power generation facilities, which emit gases like carbon dioxide and nitrogen dioxide.

Fugitive Emissions

Fugitive emissions arise from dust resulting from traffic, storage, and transportation processes. This dust can be re-suspended and contribute to air pollution.

Pollutants Released by Mining Activities

Particulate Matter

Mining activities release particulate matter into the air, including total suspended particulate matter (TSP) and smaller particles like PM10 and PM2.5, which can have respiratory health impacts.

Gaseous Emissions

In addition to particulate matter, mining releases gaseous pollutants such as carbon dioxide, carbon monoxide, nitrogen oxides, and sulfur dioxide.

Aerosols

Hydrometallurgical processes used in mining can generate aerosols, which contribute to air pollution.

Toxic Metals

The smelting process, where ore is heated to extract metals, releases toxins like mercury, arsenic, sulfur dioxide, zinc, cadmium, and uranium. These toxins can have severe health impacts on workers and nearby communities, including impaired vision, muscle weakness, kidney damage, and increased risk of cancer.

Greenhouse Gases

Smelters release significant amounts of greenhouse gases, such as carbon dioxide and perfluorocarbons (PFCs). PFCs are particularly potent heat-trapping gases that can remain in the atmosphere for tens of thousands of years.

Impact of Air Pollution from Mining

Mining-related air pollution has severe consequences for both the environment and human health. It contributes to climate change, as the mining industry emits carbon through transportation and energy use. Additionally, the release of toxins and greenhouse gases affects air quality, leading to respiratory issues and other health problems for nearby communities.

Mitigating Air Pollution from Mining

To reduce the impact of mining on air quality, continuous emission monitoring and measurement are crucial. Advancements in sensor technology have made it easier to monitor air quality levels at different stages of the mining process. By identifying sources of emissions and implementing dust reduction techniques, it is possible to minimize the environmental and health impacts of mining activities.

Soil erosion

Erosion also impacts the soil's ability to store water and nutrients, leading to higher rates of runoff and the loss of newly planted crops. The exposed subsoil often has inferior physical and chemical properties, further hindering agricultural endeavours.

Moreover, soil erosion can have downstream effects, including siltation of watercourses and water storages, and reduced water quality in creeks, rivers, and coastal areas. The eroded soil, which may contain nutrients, fertilisers, and pesticides, can be deposited in low-lying areas, affecting the surrounding ecosystems.

In the context of mining, soil erosion can interfere with natural drainage patterns, leading to the siltation of waterways. This was evident in the Ok Tedi Mine in Papua New Guinea, where soil erosion significantly affected surrounding areas.

To mitigate soil erosion, various techniques can be employed, such as vegetation restoration, contour ploughing, and the creation of buffer strips to protect vulnerable areas.

Biodiversity loss

Mining activities also contribute to pollution, which has far-reaching consequences for biodiversity. For instance, water pollution from mine waste and tailings can contaminate nearby water bodies, affecting aquatic life and rendering water unsuitable for drinking. Acid mine drainage, caused by the exposure of sulphide minerals to water and oxygen, is a significant issue that can persist for extended periods, even after mining activities have ceased. Heavy metal contamination is another concern, where metals such as arsenic, lead, and cadmium can leach into waterways, posing risks to both wildlife and humans.

Additionally, soil erosion caused by mining activities can decrease water availability for plant growth, leading to a decline in plant biodiversity. The release of air pollutants can also interfere with plant metabolic functions, impacting plant growth and altering the composition of plant communities.

The impacts of mining on biodiversity are complex and vary depending on the specific context. Endemic species, which require specific environmental conditions, are particularly vulnerable to even slight modifications in their habitat. Furthermore, the loss of biodiversity can have cascading effects on food chains, with potential consequences for species higher up the food chain due to biomagnification.

To address these issues, effective conservation strategies are necessary. This includes identifying biodiversity priorities, conducting comprehensive impact assessments, and implementing long-term strategic management plans that follow a mitigation hierarchy, aiming to avoid, minimise, and offset adverse impacts on biodiversity.

Noise pollution

Noise is defined as an unwanted or unpleasant sound, and noise pollution refers to when there is an excessive amount of noise, or an unpleasant sound that disrupts the natural balance. Sources of noise pollution include road traffic, industry, railways, and airports. It has been reported by the World Health Organization (WHO) that about 100 million people are affected by road noise in the European Union (EU), and approximately 1.6 million years of healthy life are lost annually. In addition, 69,000 hospital admissions and 15,900 instances of early death in the EU every year are attributed to noise pollution.

Mining operations, including processing plants, blasting, and machinery, are significant contributors to noise pollution in surrounding areas. Before commencing mining activities, it is essential to conduct an Environmental Impact Assessment (EIA) to identify and quantify the potential noise impacts. This involves collecting data on existing noise levels, predicting the maximum impact, and proposing mitigation measures.

The health effects of noise pollution include psychological problems such as anxiety, depression, stress, and fatigue, as well as physical issues like increased pulse rate, high blood pressure, and narrowed blood vessels. It can also lead to nervousness, sleeplessness, and fatigue, which are common complaints among mine workers. Additionally, noise pollution can negatively impact teaching and learning, mental activities, verbal communication, and sleep.

To control noise pollution, various techniques can be employed at the source of the sound, along its transmission pathway, and at the receiver. This includes reducing sound production, interposing the sound path (e.g., using insulating materials), and defending the sound receiver (e.g., providing protective hearing devices for workers).

In the context of mining, some specific strategies to mitigate noise pollution include:

• Using quieter machinery and equipment
• Directing highways away from populous zones
• Walling or planting vegetation along highways to reduce noise propagation
• Implementing mufflers in air compressors, jackhammers, and other equipment
• Following regulations and standards for aircraft engine noise at airports

Frequently asked questions