Acid mine drainage AMD is a major environmental issue caused by the exposure of sulfide minerals, such as pyrite FeS2 , to water and oxygen when mining activities take place. The primary chemical reactions involved in acid mine drainage are the oxidation of pyrite and the subsequent formation of sulfuric acid and dissolved iron. The reactions can be summarized as follows:1. Pyrite oxidation:2FeS2 s + 7O2 g + 2H2O l 2Fe2+ aq + 4SO42- aq + 4H+ aq 2. Formation of sulfuric acid:H2O l + SO2 g H2SO3 aq H2SO3 aq + 1/2O2 g H2SO4 aq These reactions lead to an increase in the concentration of hydrogen ions H+ , which lowers the pH of the water, making it more acidic. The acidic water can dissolve other minerals and metals present in the rocks, such as aluminum, manganese, and heavy metals like lead, copper, and zinc. This increases the mineral content of the water and can have severe consequences for aquatic life and water quality.The acidification of water bodies due to acid mine drainage can lead to the following effects:1. The solubility of many toxic metals increases at lower pH values, leading to higher concentrations of these metals in the water, which can be harmful to aquatic organisms and contaminate the food chain.2. The increased acidity can directly harm aquatic life, as many species are sensitive to changes in pH and may not survive in highly acidic conditions.3. The dissolution of minerals can lead to the formation of metal hydroxides, which can coat the surfaces of stream beds and lake bottoms, reducing the available habitat for benthic organisms and disrupting the ecosystem.4. Acid mine drainage can also affect the quality of drinking water sources, making it unsafe for human consumption and increasing the costs of water treatment.In summary, the chemical reactions involved in acid mine drainage, primarily the oxidation of pyrite and the formation of sulfuric acid, lead to a decrease in pH and an increase in the mineral content of water bodies. This can have severe consequences for aquatic life, water quality, and human health.