Mercury Pollution: Sources And Origins

Mercury is a highly toxic chemical that poses a significant threat to human and environmental ecosystems. Mercury pollution has various sources, including both natural and human activities. One of the primary sources of mercury pollution is coal-burning power plants, which release mercury into the atmosphere when coal is burned. Mercury can also enter water bodies through precipitation, contaminating fish and other wildlife, which, when consumed by humans, can lead to serious health issues. Other sources of mercury pollution include industrial activities, mining, and the improper disposal of items containing mercury. While policies and regulations have been implemented to limit mercury emissions, such as the Mercury and Air Toxics Standards (MATS), the fight against mercury pollution remains an ongoing challenge.

Coal-burning power plants

Mercury (Hg) is a global pollutant that poses significant risks to human and ecosystem health. One major source of mercury pollution is coal-burning power plants, which emit mercury into the atmosphere during the combustion of coal. This is a pressing issue as mercury emitted from these power plants can have detrimental effects on the health of nearby communities, particularly vulnerable groups such as children and low-income populations.

Coal often contains trace amounts of mercury, and when it is burned, this mercury is released into the atmosphere. The combustion of lignite coal, a type of coal with especially high mercury content, is a significant contributor to mercury emissions from power plants. The released mercury then enters the planet's atmosphere, waterways, and wildlife before eventually making its way into our bodies. This journey does not diminish the neurotoxic effects of mercury, making it a serious health concern.

According to studies, the majority of coal-burning power plants emit approximately 5 kilograms of mercury per year, which is considered acceptable by the EPA's standards. However, there are outliers, such as clusters of lignite-burning power plants in certain regions, that emit over 100 kilograms of mercury annually. These high emissions are unacceptable and unnecessary, as relatively inexpensive technologies, such as activated carbon injection, can significantly reduce mercury and other heavy metal emissions.

The U.S. Environmental Protection Agency (EPA) has recognized the urgency of addressing mercury pollution from coal-burning power plants. They have issued new regulations to tighten mercury emissions standards, aiming to reduce allowable mercury emissions from lignite coal plants by 70%. These stronger standards are expected to benefit the health of all individuals, especially those residing near the power plants, who are often from marginalized communities.

It is important to note that mercury emissions from coal-burning power plants are not limited to the immediate vicinity of the plants themselves. Research conducted in Indianapolis revealed a plume of mercury extending over 30 miles from a coal-fired power plant, impacting the surrounding environment and potentially affecting rural areas far beyond city limits. This highlights the far-reaching consequences of mercury pollution from power plants and the need for comprehensive solutions to address this issue.

In conclusion, coal-burning power plants are a significant source of mercury pollution, and their impact on human health and the environment cannot be overstated. While there have been efforts to reduce mercury emissions from these plants, more stringent measures and the adoption of improved technologies are necessary to mitigate the harmful effects of this toxic pollutant on both a local and global scale.

Industrial sources

Mercury pollution is a pressing issue that poses significant risks to both human health and the environment. While mercury does occur naturally in the Earth's crust, human activities, particularly industrial processes, have led to widespread global mercury pollution.

Artisanal and small-scale gold mining (ASGM) is another significant industrial source of mercury pollution. Mercury is often used in gold mining to extract the metal from ore, and this process releases mercury into the environment. ASGM is the largest source of anthropogenic mercury emissions, accounting for 37.7% of global emissions, according to the United Nations Environment Programme. The health effects of mercury use in ASGM are particularly harmful to vulnerable populations.

Other industrial processes that contribute to mercury pollution include non-ferrous metal production, which accounts for 15% of global emissions, and cement production, which accounts for 11%. Industrial waste incinerators and industrial boilers can also release mercury into the environment.

The release of mercury from these industrial sources has severe ecological and human health consequences. Mercury emitted into the air eventually settles into water bodies or onto land, where it can be transformed by bacteria into methylmercury, a highly toxic organic compound. This compound builds up in fish, shellfish, and animals that consume fish, leading to bioaccumulation. As a result, the consumption of contaminated fish and shellfish is a primary source of human exposure to mercury, with potential toxic effects on the nervous, digestive, and immune systems, as well as various organs.

Mining

Mercury pollution from mining is a significant environmental issue, particularly in the context of artisanal and small-scale gold mining (ASGM). ASGM involves the use of mercury to extract gold from ore or sediment, and it is estimated that between 10 and 19 million people engage in this practice in over 70 countries. The intentional use of mercury in ASGM has severe health and environmental impacts.

In ASGM, mercury is used to form an amalgam with gold, which is then heated to distill the mercury and isolate the gold. This process releases mercury into the air, soil, and water, leading to contamination. The health effects of mercury exposure are well-documented, including neurological damage, respiratory and cardiovascular issues, and developmental complications in children. Mercury contamination also affects local ecosystems, with high concentrations found in plants, animals, and water sources near mining sites.

Gold shops, which are key components of the ASGM gold supply chain, have been identified as significant sources of mercury emissions. Studies have found that emissions from gold shops pose hazards to both workers and residents in the surrounding communities, with mercury levels far exceeding recommended levels. The impact of these emissions can extend beyond the immediate area, as mercury can be deposited and cycled to distant destinations.

Efforts to reduce mercury pollution from mining are ongoing. The Minamata Convention on Mercury, ratified by over 50 parties, aims to control the trade, use, and emissions of mercury. Additionally, the US EPA and ANL have developed the Mercury Capture System (MCS), which is designed to capture mercury at the emission source and reduce gold shop-related emissions. Other strategies include introducing portable and low-cost mercury sensors, remediation technologies, and mercury-free mining techniques.

Mercury is also naturally occurring in the earth's crust, and mining activities can release this mercury into the environment. Large-scale mining operations, such as those in Chile, have been associated with severe air pollution, with mercury levels in the air far exceeding health standards. Abandoned and inactive mining sites can also pose long-term dangers to local communities due to the presence of contaminants.

Improper disposal

The improper disposal of mercury can occur in several ways. One common issue is the disposal of mercury-containing products in regular trash or recycling bins. Some people may be unaware that items such as thermometers, light bulbs, batteries, thermostats, barometers, manometers, and certain switches contain mercury. As a result, these items may end up in landfills or incinerators, leading to mercury releases into the soil, water, and air.

Another form of improper disposal is the inappropriate handling and storage of mercury within households. Mercury is a highly volatile substance that can easily evaporate at room temperature. If mercury-containing products are not properly sealed or stored, spills or leaks can occur, leading to contamination of indoor environments and, eventually, outdoor ecosystems.

To address these issues, proper disposal methods for mercury-containing products are essential. Many municipalities have established Household Hazardous Waste Collection sites or special collection days where residents can bring their mercury waste for safe disposal. It is crucial to package and transport mercury waste with extreme caution, following guidelines provided by local waste management authorities or environmental agencies.

Additionally, it is worth noting that some states and local jurisdictions have implemented regulations that exceed federal hazardous waste standards. For example, Vermont has banned all mercury-containing waste from landfills, including waste generated by households. By enforcing stricter regulations, these jurisdictions aim to reduce the improper disposal of mercury and mitigate its environmental and health impacts.

Atmospheric deposition

Wet deposition occurs when Hg is removed from the atmosphere through precipitation, such as rain or snow. This can result in Hg being deposited on land or water bodies, where it can contaminate soil, vegetation, and aquatic ecosystems. Dry deposition, on the other hand, involves the removal of Hg from the atmosphere through processes like gravitational settling, aerosol surface deposition, and gas absorption by plants and other surfaces.

The Athabasca oil sands region in northern Alberta, Canada, is an area of particular concern regarding atmospheric deposition of Hg. Studies have shown that oil sands developments are a direct source of methylmercury (MeHg), a neurotoxin that can bioaccumulate in fish and wildlife. Sampling of snowpack in the region revealed high levels of both THg (total Hg) and MeHg, with concentrations increasing in proximity to major developments. This suggests that atmospheric deposition is a significant pathway for Hg pollution in the area, posing potential health risks to humans who consume contaminated fish and wildlife.

To address the issue of atmospheric deposition of Hg, policies and regulations have been implemented to limit Hg releases from human activities and control its transport within and between the atmosphere, freshwater, the lithosphere, and the ocean. However, more information is needed to fully understand the global circulation and impact of Hg emissions and to effectively manage the risks associated with this toxic pollutant.

Frequently asked questions