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Geochemistry of Acid Mine Drainage

Surface Water Hydrology

  1. Roger C. Viadero

Published Online: 15 APR 2005

DOI: 10.1002/047147844X.sw356

Water Encyclopedia

Water Encyclopedia

How to Cite

Viadero, R. C. 2005. Geochemistry of Acid Mine Drainage. Water Encyclopedia. 3:13–15.

Author Information

  1. West Virginia University, Morgantown, West Virginia

Publication History

  1. Published Online: 15 APR 2005


Acid mine drainage (AMD) results when metal pyrites come in contact with water and/or air, to form dilute sulfuric acid. For instance, iron pyrite (FeS2) is the major iron-sulfur impurity found in mined earth, particularly in the eastern United States where coal mining is prevalent. Typically, AMD waters contain elevated concentrations of SO4, Fe, Mn, Al, and other metal ions. As an example, representative AMD water quality parameters from the Roaring Creek-Grassy Run Watershed, located in Elkins, West Virginia, include pH from 2.4 to 3.3, mineral acidities from 2.4 to 980 mg/L as CaCO3, dissolved iron between 35 and 260 mg/L, and sulfate concentrations from 190 to 740 mg/L.

In contrast, copper and arsenic sulfide compounds associated with “hard rock” mining operations are common in the western United States; such compounds are generally much less prevalent in the east. In such instances, sulfide containing minerals such as pyrrhotite (FeS), arsenopyrite (FeAsS), and chalcopyrite (CuFeS2) can produce acidic drainage when oxidized.


  • acid mine drainage;
  • AMD;
  • acidity;
  • alkalinity;
  • cations;
  • precipitation–dissolution;
  • metal pyrite;
  • sulfur;
  • microbially mediated oxidation;
  • carbonate equilibrium