Acid Mine Drainage

Acid mine draining flowing in a stream near the Iron Mountain mine in northern California near Redding. Acid mine drainage (AMD) is metal-rich, acidic water that is the result of water from mining activities flowing over or through rocks containing pyrite, a sulfur bearing mineral. This water reacts with pyrite and air to form sulfuric acid and dissolved iron. The chemical reactions that form AMD are sped up greatly by the activity of iron- and sulfur-oxidizing microbes, including bacteria and Archaea (formerly known as archaebacteria). AMD also further dissolves other heavy metals that are present at Iron Mountain (copper, zinc and cadmium) into ground or surface water.