Model Answer
0 min readIntroduction
Mercury (Hg) is a naturally occurring element that exists in various forms, including elemental, inorganic, and organic compounds. While present in the environment naturally, human activities have significantly increased its concentration, leading to widespread pollution. Mercury pollution is a global environmental health threat, recognized by the World Health Organization (WHO) as one of the ‘Ten Chemicals of Major Public Health Concern’. The Minamata disease outbreak in Japan (1950s-1960s) serves as a stark reminder of the devastating consequences of mercury poisoning, prompting increased international attention and regulatory efforts. This note will explore the sources, impacts, and mitigation strategies related to mercury pollution.
Sources of Mercury Pollution
Mercury enters the environment from both natural and anthropogenic sources.
- Natural Sources: Volcanic eruptions, weathering of rocks, and forest fires release mercury into the atmosphere, water, and soil.
- Anthropogenic Sources: These are the primary contributors to increased mercury levels.
- Artisanal and Small-Scale Gold Mining (ASGM): This is the largest single source of mercury emissions globally, accounting for approximately 37% of total emissions (UN Environment Programme, 2019).
- Coal Combustion: Burning coal for power generation releases significant amounts of mercury into the atmosphere.
- Industrial Processes: Chlor-alkali production, cement manufacturing, and metal smelting contribute to mercury pollution.
- Waste Incineration: Burning mercury-containing waste (e.g., batteries, fluorescent lamps) releases mercury vapor.
- Dental Amalgams: Although a smaller source, dental fillings containing mercury release small amounts of the element.
Environmental Impacts of Mercury Pollution
Mercury undergoes complex transformations in the environment, impacting various ecosystems.
- Atmospheric Transport: Mercury released into the atmosphere can travel long distances, leading to global distribution.
- Deposition: Atmospheric mercury deposits onto land and water surfaces through wet and dry deposition.
- Bioaccumulation and Biomagnification: Mercury, particularly methylmercury (an organic form), accumulates in aquatic organisms. As it moves up the food chain, its concentration increases in predators (biomagnification), posing a significant risk to fish-eating birds, mammals, and humans.
- Water Contamination: Mercury contaminates rivers, lakes, and oceans, affecting aquatic life and potentially entering drinking water sources.
- Soil Contamination: Mercury accumulates in soil, impacting plant growth and potentially entering the food chain.
Health Impacts of Mercury Pollution
Exposure to mercury can have severe health consequences, depending on the form, dose, and duration of exposure.
- Neurological Effects: Methylmercury is a neurotoxin that can damage the brain and nervous system, particularly in developing fetuses and young children.
- Kidney Damage: Exposure to inorganic mercury can cause kidney damage.
- Cardiovascular Effects: Some studies suggest a link between mercury exposure and cardiovascular disease.
- Minamata Disease: A neurological syndrome caused by severe mercury poisoning, characterized by ataxia, speech and motor disturbances, and sensory impairment.
Mitigation and Control Measures
Addressing mercury pollution requires a multi-faceted approach.
- International Agreements: The Minamata Convention on Mercury (2013) is a global treaty aimed at protecting human health and the environment from the adverse effects of mercury. It covers a range of measures, including reducing mercury emissions, phasing out mercury-added products, and managing mercury waste.
- National Regulations: Many countries have implemented national regulations to control mercury emissions and use. For example, the US has the Clean Air Mercury Rule (CAMR) and regulations on mercury emissions from power plants.
- Technological Solutions:
- Flue Gas Desulfurization (FGD): Used in power plants to remove mercury along with sulfur dioxide.
- Activated Carbon Injection (ACI): Injected into flue gases to adsorb mercury.
- Improved Mining Practices: Reducing mercury use in ASGM through alternative gold extraction techniques.
- Public Awareness: Educating the public about the risks of mercury exposure and promoting safe handling and disposal of mercury-containing products.
| Pollution Control Measure | Description |
|---|---|
| Minamata Convention on Mercury | Global treaty to reduce mercury emissions and protect human health. |
| Flue Gas Desulfurization (FGD) | Technology used in power plants to remove mercury and sulfur dioxide. |
| Activated Carbon Injection (ACI) | Technology used to adsorb mercury from flue gases. |
Conclusion
Mercury pollution poses a significant threat to both environmental and human health. While natural sources contribute to mercury levels, anthropogenic activities, particularly ASGM and coal combustion, are the primary drivers of increased pollution. Effective mitigation requires a combination of international cooperation (like the Minamata Convention), stringent national regulations, technological advancements, and public awareness. Continued monitoring, research, and investment in cleaner technologies are crucial to minimize the risks associated with this pervasive pollutant and safeguard future generations.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.