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Environmental pollution focus area: Acid mine drainage
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There are more than 500,000 abandoned coal and metal mines in the US adversely affecting 12,000 miles of rivers and streams and more than 180,000 acres of lakes and reservoirs with acid mine drainage. This term refers to water with high concentrations of sulfuric acid draining out of surface or subsurface mines. It affects to some degree most regions in both hemispheres, and is therefore a globally distributed environmental problem. It was recently one of the issues raised in the controversial proposal to initiate gold mining in Rosia Montana, Romania. Mining activities expose gargantuan quantities of buried lithosphere materials to the oxidizing environment of the open atmosphere as the compound of commercial interest is extracted. Chemical reactions occur that compress hundreds of thousand of years of normal weathering into decades. Reactions involving sulfide-bearing mineral deposits, such as iron disulfide (FeS sub(2)), produce sulfuric acid, which imparts a stable pH of 2.5-3 to water percolating through the fractured rock. Acid conditions subsequently mobilize metals such as aluminum, copper, cadmium zinc, manganese, and lead from rock and enable their transport in water streams draining the mine area. Naturally occurring limestone (CaCO sub(3)) deposits mitigate the risk that acid rock drainage will occur in any given mining region, as oxidative weathering produces alkaline conditions. Acid mine drainage adversely impacts surface water, groundwater and riparian areas by contaminating the ecosystem with toxic metals, and altering downstream ecologies with delivery of acid.
Article Subject Terms: Acidic wastes; Aluminum; Cadmium; Coal; Congress; Drainage; Ecology; Groundwater; Iron; Lakes; Lead; Metals; Mines; Mining; Reservoirs; Riparian environments; Rivers; Streams; Sulfuric acid; Surface water; Water pollution; Weathering; mine; drainage; weathering; Article Geographic Terms: Romania; X 24156 Environmental impact; M3 1010 Issues in Sustainable; Development
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