Model Answer
0 min readIntroduction
Mining, a crucial activity for resource extraction, inevitably impacts the surrounding environment, particularly water resources. Water pollution stemming from mining operations is a significant global concern, affecting both surface water bodies like rivers and lakes, and subsurface aquifers. This pollution arises from a complex interplay of geological, chemical, and hydrological processes triggered by mining activities. The release of heavy metals, acid mine drainage (AMD), and increased sediment loads pose serious threats to aquatic ecosystems and human health. Recent incidents like the widespread contamination in mining areas of Jharkhand and Odisha highlight the urgency of addressing this issue.
Pollution of Surface Water due to Mining Activities
Surface water pollution from mining is often visible and widespread. The primary sources and pollutants include:
- Acid Mine Drainage (AMD): This is arguably the most significant form of surface water pollution. It occurs when sulfide minerals (like pyrite – FeS2) are exposed to air and water, oxidizing to form sulfuric acid. This acidic water dissolves heavy metals from the surrounding rock, creating a toxic cocktail.
- Heavy Metal Contamination: Mining often releases heavy metals like mercury, lead, arsenic, cadmium, and chromium into surface waters. These metals are toxic even at low concentrations and can bioaccumulate in the food chain.
- Sedimentation: Mining activities, particularly open-pit mining and construction of tailings dams, lead to increased erosion and sedimentation in nearby rivers and streams. This increases turbidity, reduces light penetration, and smothers aquatic habitats.
- Chemical Reagents: Processes like heap leaching use chemicals like cyanide and mercury to extract metals. Leakage or improper disposal of these reagents can severely contaminate surface waters.
- Tailings Dam Failures: The catastrophic failure of tailings dams (structures used to store mining waste) can release massive amounts of pollutants into rivers and lakes, causing widespread devastation.
Pollution of Groundwater due to Mining Activities
Groundwater pollution is often less visible but can be more persistent and difficult to remediate. Key sources and pollutants include:
- Leaching from Tailings Dams and Waste Rock Piles: Even without catastrophic failures, tailings dams and waste rock piles can leach pollutants into groundwater over long periods.
- Infiltration from Open Pits: Open-pit mines can act as funnels for rainwater, which then percolates through contaminated rock and soil, reaching the groundwater table.
- Fractured Rock Permeability: Mining-induced fracturing of rock formations can create pathways for pollutants to migrate rapidly through the subsurface.
- Underground Mining: Abandoned underground mines can fill with water, creating a source of contaminated groundwater that can discharge into nearby aquifers.
- Blasting and Drilling: These activities can alter groundwater flow patterns and introduce pollutants into the aquifer.
Specific Pollutants and their Impacts
| Pollutant | Source | Impacts |
|---|---|---|
| Sulfuric Acid | AMD | Lowers pH, mobilizes heavy metals, corrodes infrastructure |
| Mercury | Gold mining, artisanal mining | Neurotoxic, bioaccumulates in fish, affects human health |
| Arsenic | Gold, copper, lead mining | Carcinogenic, causes skin lesions, cardiovascular disease |
| Cyanide | Gold extraction (heap leaching) | Highly toxic, inhibits cellular respiration |
| Sediment | Erosion from mining sites | Reduces light penetration, smothers aquatic habitats, clogs waterways |
Regulatory Framework and Mitigation Strategies
India has several regulations aimed at mitigating water pollution from mining:
- Water (Prevention and Control of Pollution) Act, 1974: Provides the framework for regulating water pollution and establishing pollution control boards.
- Environment (Protection) Act, 1986: Empowers the government to take measures to protect and improve the environment.
- National Green Tribunal (NGT): Provides a forum for resolving environmental disputes.
- Mining Legislation: Various state-level mining regulations mandate environmental impact assessments (EIAs) and the implementation of environmental management plans.
Mitigation strategies include:
- Proper Waste Management: Safe disposal of tailings and waste rock, including lining of tailings dams and covering waste rock piles.
- Water Treatment: Treatment of AMD and contaminated mine water using techniques like neutralization, precipitation, and filtration.
- Rehabilitation of Mining Sites: Restoring disturbed land to a stable and productive state, including revegetation and erosion control.
- Monitoring and Surveillance: Regular monitoring of water quality to detect and address pollution problems.
- Sustainable Mining Practices: Implementing best management practices to minimize environmental impacts.
Conclusion
Mining-induced water pollution presents a complex environmental challenge requiring a multi-faceted approach. While mining is essential for economic development, its environmental consequences, particularly the contamination of surface and groundwater resources, cannot be ignored. Strengthening regulatory frameworks, promoting sustainable mining practices, and investing in effective remediation technologies are crucial for protecting water resources and ensuring the long-term health of ecosystems and communities. Continuous monitoring, strict enforcement of regulations, and community participation are vital for mitigating the adverse impacts of mining on water quality.
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.