Meghan Hodges
Mercury is a naturally occurring element that has been directly mobilized by humans into aquatic and terrestrial ecosystems through mining, the use of Hg in precious metal extraction, and its presence as a trace contaminant in many materials. Mercury is a global pollutant that affects human and ecosystem health. It is considered a primary pollutant, which is an air pollutant emitted directly from a source. Primary pollutants are of concern as they can be harmful to humans, animals, and plants. Their contribution to the formation of secondary pollutants is also concerning, as this is what causes harmful ground-level ozone to form, along with different smogs, especially in densely populated cities.
| Characteristics | Values |
|---|---|
| Mercury as a pollutant | Mercury is a global pollutant that affects human and ecosystem health. |
| Mercury as a primary pollutant | Mercury is a primary pollutant as it is emitted directly from a source, in this case, human activity. |
| Sources of mercury as a pollutant | Mercury is a naturally occurring element but has been directly mobilized by humans for thousands of years into aquatic and terrestrial ecosystems through mining, the use of Hg in precious metal extraction, its presence as a trace contaminant in many materials (e.g. coal, metal ores), and its use in products (e.g. paint, electronic devices) and by the industry. |
| Impact of mercury as a pollutant | The impact of mercury as a pollutant includes contamination of the air, water, and land. It affects human health, wildlife, and the environment. |
| Control of mercury pollution | Policies and regulations have been implemented to limit Hg releases from human activities and to control its transport within and among the atmosphere, freshwaters, the lithosphere, and the ocean at local, regional, and global scales. |
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What You'll Learn
Mercury is a global pollutant
Mercury (Hg) is a naturally occurring element that has been directly mobilized by humans for thousands of years into aquatic and terrestrial ecosystems through mining, the use of Hg in precious metal extraction, and its presence as a trace contaminant in many materials, such as coal and metal ores. Mercury is a global pollutant that affects human and ecosystem health.
The atmosphere is the primary transport pathway for Hg emissions, while land and ocean processes play a crucial role in redistributing Hg in terrestrial, freshwater, and marine ecosystems. The main sources of anthropogenic Hg emissions include coal-fired electricity generation, particularly in developing regions, and various industrial activities. These emissions have led to increases in Hg reservoirs and subsequent secondary Hg emissions, facilitating its global distribution.
The ultimate fate of emitted Hg is often recalcitrant soil pools, deep ocean waters, and sediments. Transfers of Hg emissions to these largely unavailable reservoirs occur over centuries and are mediated through atmospheric exchanges, wet and dry deposition, and evasion from vegetation, soil organic matter, and ocean surfaces. The production of methylmercury, which occurs primarily in reducing zones in freshwater, terrestrial, and coastal environments, is a key link between inorganic Hg inputs and the exposure of humans and wildlife.
Elevated human exposure to methylmercury results mainly from consuming estuarine and marine fish. Developing fetuses are most at risk from this neurotoxin, but the health effects on highly exposed populations and wildlife are also concerning. The socio-economic consequences of Hg contamination have led to policies and regulations aimed at limiting Hg releases from human activities and controlling its transport within and between the atmosphere, freshwaters, the lithosphere, and the ocean at local, regional, and global scales.
Mercury is indeed a primary pollutant, as it is emitted directly from sources such as combustion facilities, cement or glass production, and waste incineration facilities. Primary pollutants, such as mercury, are of significant concern due to their direct harm to humans, animals, and plants, as well as their contribution to forming secondary pollutants.
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Sources of mercury
Mercury is a naturally occurring element, but human activities have more than doubled the amount of mercury in the atmosphere in the last 150 years. Natural sources of mercury emissions include volcanoes, geothermal springs, geologic deposits, and the ocean. However, human-related sources of mercury emissions are more concerning and include coal combustion, waste incineration, industrial uses, and mining. Mercury is a known neurotoxin, and its presence in the environment can have serious effects on human health and wildlife.
Coal combustion is a significant source of mercury emissions. Mercury is often present as a trace contaminant in coal, and when coal is burned, the mercury is released into the atmosphere. This is a particular concern in the developing world, especially in Asia, where coal-fired electricity generation is expanding. The combustion of coal has been identified as the main cause of mercury contamination in fish, which is a primary source of human exposure to mercury.
Industrial uses of mercury also contribute significantly to emissions. Mercury has been used in various industrial processes, including the chlor-alkali industry and as a catalyst. It has also been used in products such as paint and electronic devices. While many of these uses have been discontinued, mercury can still be found in some products, such as thermometers, and can be released into the environment if not properly contained or cleaned up.
Mining is another source of mercury emissions. Mercury can be released into the environment during mining operations, particularly when precious metals are being extracted. Additionally, mercury can be present as a trace contaminant in metal ores, which can lead to its release during smelting processes.
Other sources of mercury emissions include waste incineration and natural geological processes. Mercury compounds have also been used in various products, such as fungicides, preservatives, antiseptics, and disinfectants, although many of these uses have been discontinued. Some medicines still use small amounts of mercury compounds as preservatives.
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Mercury's impact on human health
Mercury is a naturally occurring element that can have toxic effects on human health, especially when it is released into the environment as a pollutant. It exists in several forms, including elemental or metallic mercury, inorganic mercury, and organic mercury compounds, all of which can pose risks to human health. When released into the environment, mercury can persist for long periods and accumulate in various ecological systems, ultimately making its way into the food chain and posing significant health risks to humans.
One of the primary ways mercury impacts human health is through the consumption of contaminated fish and shellfish. Methylmercury, an organic form of mercury, is produced by microbial activity in aquatic environments, and it bioaccumulates in the tissues of fish and shellfish. This means that higher trophic level predators, such as larger fish and those that live longer, can accumulate significant amounts of mercury in their tissues over time. When humans consume these contaminated fish, the methylmercury is easily absorbed by the body and can reach the brain and other vital organs.
Methylmercury exposure, even at low levels, can have harmful effects on the nervous system, particularly during critical stages of development. Prenatal and early childhood exposure to methylmercury can impair cognitive function, language skills, memory, attention, and fine motor skills. In severe cases, high-level exposure can result in neurological symptoms such as tremors, impaired vision and hearing, paralysis, and, in extreme cases, even death. Additionally, methylmercury has been associated with an increased risk of cardiovascular issues in adults, including higher blood pressure and a faster heart rate.
Inorganic mercury can also have detrimental effects on human health. When inhaled or ingested, inorganic mercury compounds, such as mercury chloride or mercury vapor, can damage the nervous, digestive, and immune systems. Acute exposure to high levels of inorganic mercury vapor may result in respiratory failure, while chronic exposure to lower levels can lead to tremors, insomnia, memory loss, neuromuscular effects, headaches, and cognitive and motor function impairments. Inorganic mercury can also have renal effects, causing damage to the kidneys and increasing the risk of kidney disease.
Elemental or metallic mercury, while less harmful than inorganic and organic forms, can still pose risks to human health. If inhaled, it can be absorbed into the bloodstream and distributed throughout the body, potentially causing neurological and behavioral effects. Prolonged exposure to metallic mercury vapor can result in more severe neurological symptoms, including irritability, nervousness, insomnia, and cognitive deficits. However, it is important to note that elemental mercury is not absorbed through the skin, so direct skin contact is typically not a cause for concern.
Overall, mercury is a potent neurotoxin that can have significant impacts on human health, even at low exposure levels. It is essential to be aware of potential sources of mercury exposure, especially through the consumption of contaminated fish and shellfish, and to take appropriate measures to minimize these risks. By understanding the harmful effects of mercury and implementing strategies to reduce pollution and exposure, we can better protect human health and the environment.
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Mercury's impact on the environment
Mercury is a naturally occurring element that has been directly mobilized by humans for thousands of years into aquatic and terrestrial ecosystems. Mercury (Hg) is a global pollutant that affects human and ecosystem health. The primary sources of anthropogenic Hg emissions are coal-fired electricity generation, mining, the use of Hg in precious metal extraction, and its presence as a trace contaminant in many materials, such as coal and metal ores. The atmosphere is the main pathway for the transport of Hg emissions, while land and ocean processes play a crucial role in redistributing Hg in terrestrial, freshwater, and marine ecosystems.
The impact of Hg on the environment is significant. Elevated human exposure to methylmercury, a neurotoxin, occurs mainly through the consumption of estuarine and marine fish. Developing fetuses are at the highest risk from methylmercury exposure, but health effects on highly exposed populations and wildlife are also a concern. The production of methylmercury occurs primarily in reducing zones in freshwater, terrestrial, and coastal environments.
The increase in Hg emissions contributes to its global distribution and accumulation in the environment. The ultimate fate of emitted Hg is its deposition in recalcitrant soil pools, deep ocean waters, and sediments. Over time, Hg emissions can transfer to unavailable reservoirs through atmospheric exchanges of wet and dry deposition and evasion from vegetation, soil organic matter, and ocean surfaces. This process occurs over centuries, highlighting the long-term impact of Hg pollution.
The socio-economic consequences of Hg contamination have led to the implementation of policies and regulations to limit Hg releases from human activities. International efforts, such as the integration of Hg science with policies, aim to control the transport and distribution of Hg within and among the atmosphere, freshwater systems, the lithosphere, and the ocean. These measures are essential to mitigate the harmful effects of Hg on human health, wildlife, and the environment.
In summary, mercury is a primary pollutant that has significant impacts on the environment. Its mobilization by human activities has led to increased Hg emissions, which affect ecosystems and human health. The consumption of contaminated fish is a primary route of exposure for humans, with developing fetuses being particularly vulnerable. International efforts to reduce Hg releases and control its transport are crucial to minimize its environmental and health impacts.
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Reducing mercury emissions
Mercury is a naturally occurring element that has been directly mobilized by humans for thousands of years into aquatic and terrestrial ecosystems through mining, the use of Hg in precious metal extraction, its presence as a trace contaminant in many materials, and its use in products and by industry. Mercury (Hg) is a global pollutant that affects human and ecosystem health.
The atmosphere is the foremost transport pathway of Hg emissions, whereas land and ocean processes play an important role in the redistribution of Hg in terrestrial, freshwater, and marine ecosystems. The ultimate fate of emitted Hg is primarily recalcitrant soil pools and deep ocean waters and sediments.
To reduce mercury emissions, several measures can be taken:
International agreements and regulations:
Mercury crosses national borders, so regional and international agreements are crucial. Legally binding agreements, such as the Minamata Convention on Mercury, which the US joined in 2013, have achieved substantial reductions in central and eastern Europe, Canada, and the USA. Additionally, multilateral environmental agreements restrict international trade in mercury chemicals and wastes.
End-of-pipe techniques:
These are control methods at the point of emission. End-of-pipe techniques, such as filtering exhaust gases, are useful when raw materials contain tiny amounts of mercury in fossil-fuelled power plants, cement production, and metal mining and processing.
Effective waste management:
Proper waste management can reduce mercury releases from spills or gradual leakage, such as from broken thermometers, auto switches, and dental amalgams. Some countries, like Sweden, require waste with higher mercury concentrations to be deposited in specially equipped landfills or deep underground to limit leaching and evaporation.
EPA standards and regulations:
The US Environmental Protection Agency (EPA) has implemented several measures to reduce mercury emissions. In 2011, the EPA issued the Mercury and Air Toxics Standards (MATS) regulation, which led to power plants installing controls and updating operations to reduce emissions from coal- and oil-fired power plants. The EPA has also issued standards for mercury emissions from chlor-alkali production, large municipal waste combustors (MWCs), and small MWCs, resulting in significant reductions. Additionally, the EPA has partnered with the Argonne National Laboratory (ANL) to design the Gold Shop Mercury Capture System (MCS) to reduce airborne mercury emissions from small-scale gold refining facilities worldwide.
Individual actions:
Individuals can also play a role in reducing mercury emissions. People can choose to buy and use products that are mercury-free or recycle and properly dispose of any mercury-containing items. They can also contact their electricity provider to learn about the source of their electricity and switch to a different energy source if possible, as coal-burning power plants release mercury into the environment. Eating fish low in mercury and limiting consumption of fish with higher mercury levels can also reduce exposure.
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Frequently asked questions
Yes, mercury is a primary pollutant. It is a naturally occurring element that has been directly mobilized by humans for thousands of years into aquatic and terrestrial ecosystems through mining, the use of Hg in precious metal extraction, and its presence as a trace contaminant in many materials.
Mercury is emitted into the environment through human activities such as coal-fired electricity generation, mining, and the use of Hg in products and industry. The atmosphere is the main transport pathway of Hg emissions, while land and ocean processes play a role in redistributing Hg in ecosystems.
Mercury pollution has negative impacts on both human and ecosystem health. Elevated human exposure to methylmercury, a neurotoxin, can occur through the consumption of contaminated estuarine and marine fish. Mercury pollution can also affect wildlife and the environment, including the production of CH3Hg, which drives the major human exposure route.
