Metal-mine drainage

{
  "id": "MLC-T-ENV-017072",
  "term": "Metal-mine drainage",
  "field": "Environment",
  "term_source": "Metal-Mine Drainage",
  "definition": "Acid mine drainage from mines producing metallic ores. A variety of metals are present as water contaminants. Acid is generated at mine sites when metal sulfide minerals are oxidized. Metal sulfide minerals are present in the host rock associated with most types of metal mining activity. Prior to mining, oxidation of these minerals and the formation of sulfuric acid is a function of natural weathering processes. The oxidation of undisturbed ore bodies followed by release of acid and mobilization of metals is slow. Discharge from such deposits poses little threat to receiving aquatic ecosystems. Extraction and beneficiation operations associated with mining activity increase the rate of these same chemical reactions by exposing large volumes of sulfide rock material with increased surface area to air and water.",
  "subject": "Environmental events",
  "references": [
    "Adapted from EPA ACID MINE DRAINAGE PREDICTION EPA 530-R-94-036 NTIS PB94-201829at http://water.epa.gov/polwaste/nps/upload/amd.pdf"
  ],
  "url": "https://mlchart.com/terminology/environment/metal-mine-drainage/"
}