I. Direct Environmental Impact
Physical structure damage
Geological disaster risk: The tailings pond has large and loose deposits, which are prone to landslides and mudslides due to heavy rain, earthquakes, etc., threatening the surrounding residents and the ecosystem.
Land occupation: Tailings accumulation occupies a large amount of land, damages the original vegetation and soil structure, and leads to land desertification or salinization.
Chemical pollution
Heavy metal pollution: Tailings often contain heavy metals such as lead, cadmium, arsenic and mercury. These metals leep into the soil and groundwater through rainwater, causing plant death and soil degradation. They also accumulate through the food chain, posing a threat to human health.
Acidic wastewater (AMD) : Sulfur-containing minerals (such as pyrite) oxidize to form sulfuric acid, making the tailings wastewater strongly acidic and dissolving more heavy metals, thus forming a long-term pollution source.
Residual reagents in mineral processing: Toxic substances such as cyanide and organic reagents used in the flotation process may seep into the environment, inhibit microbial activity, and disrupt ecological balance.
Water resource pollution
Surface water and groundwater pollution: Leakage or dam failure of tailings ponds can directly pollute rivers and lakes, causing abnormal pH values of water bodies and reduced dissolved oxygen, threatening the survival of aquatic organisms.
Water source safety: Heavy metals and toxic substances enter drinking water sources through runoff, increasing the health risks to regional residents (such as cancer and liver and kidney damage).
Ii. Impact on Biodiversity
Vegetation destruction
The soil in the tailings accumulation area is poor and has a high content of heavy metals, which inhibits the development of plant roots, leads to a decrease in vegetation coverage, and aggravates soil erosion.
Loss of animal habitats
The construction of tailings ponds and the spread of pollution encroach upon the habitats of wild animals. Pollutants directly poison organisms or are transferred through the food chain, leading to a reduction in population or even local extinction.
Imbalance of the microbial system
Heavy metals and acidic conditions inhibit the activity of soil microorganisms, affect the decomposition of organic matter and nutrient cycling, and further weaken the ecosystem's resilience.
Iii. Long-term Cumulative Effect
Persistent pollution
Heavy metals are difficult to degrade in the environment. Long-term accumulation may cause a "chemical time bomb" effect and still pose a threat to the ecosystem decades later.
Dust pollution
Under dry conditions, tailings particles spread with the wind to form dust, polluting the air and causing respiratory diseases among the surrounding residents.
Iv. Governance and Mitigation Measures
Engineering and technical means
Tailings dry storage: Reduces the generation of leachate and lowers the risk of dam failure.
Anti-seepage and covering: Materials such as clay and HDPE film are used to prevent the migration of pollutants. The surface is covered with soil and tolerant plants are planted.
Wastewater treatment: Neutralize acidic wastewater, precipitate heavy metals, and achieve recycling.
Ecological restoration technology
Phytoremediation: Screen super-rich plants (such as centipede grass for arsenic absorption) to adsorb heavy metals and gradually restore soil functions.
Microbial remediation: Utilizing heavy metal-resistant strains or sulfate-reducing bacteria to fix pollutants.
In-situ passivation: Add improvers such as lime and biochar to reduce the activity of heavy metals.
Management and Monitoring
Establish a full life cycle monitoring system for tailings ponds and regularly test the quality of leachate, groundwater and soil.
Formulate strict regulations to promote the resource utilization of tailings (such as for making building materials and backfilling mines).
V. Summary
The impact of tailings on the ecological environment has multi-dimensional and cross-media characteristics, and risk prevention and control should be achieved through a combination of source reduction, process control and end-of-pipe treatment. With the promotion of the concept of green mines, the resource utilization of tailings (such as extracting valuable elements and preparing building materials) will become an important direction to reduce the environmental burden.
