Abstract
Metal sulfides in coal and associated rocks of the Appalachian coalfield weather in the presence of air and water to produce metalliferous, acidic mine drainage (AMD). When watersheds lack sufficient geologic buffering, AMD from surface and underground mines can impair surface waters. Appalachian coalfield AMD is similar to acidic mine waters found worldwide and typically contains elevated acidity; low or no alkalinity; elevated iron, aluminum, manganese, sulfate, and conductivity; and localized elevated trace metals and metalloids including copper, zinc, selenium, and arsenic. AMD has impaired thousands of kilometers of streams in Appalachia with metal-rich, acidic waters leading to metal-rich sediments, impaired aquatic habitat, and nutrient limitations. Treatment has often been undertaken with the goal of eliminating these impacts. Treatment strategies include active treatment, where alkaline chemicals are added to AMD or impaired streams, and passive treatment, where alkaline addition and metal removal are accomplished in pond or wetland-based systems through combinations of alkaline material, organic substrate, and hydraulic retention. Treatment of AMD in Appalachia has improved water quality and biological communities at thousands of sites. Waters treated for AMD typically remain high in conductivity and with biological communities less complex than those at unimpacted sites.
Published Version
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