Amd Remediation At Shoup 's Run Watershed

1664 WordsDec 11, 20167 Pages
AMD Remediation at Shoup’s Run Watershed Alanna O’Neil Introduction: The main pollutant of surface water in the mid-Atlantic region is Acid Mine Drainage, AMD, also called Abandoned Mine Drainage. AMD is a nonpoint source pollution that has degraded more than 4,500 stream miles, in just the mid-Atlantic region, due to the drainage of metal-rich water from mining activities (Jacobs). The runoff is extremely acidic due to the exposure of pyrite containing rocks, a sulfur bearing mineral (FeS2), during mining activities, and the chemical reactions associated with the contact of air and water with such rocks. As a result of such chemical reactions, sulfuric acid (H2SO4) is produced. Several chemical reactions take place and are as follows: 1. 2FeS2(s) + 7O2 (g) +2H2O(l) → 2Fe2+(aq) + 4SO4-2(aq) + 4H+(aq) 2. 4Fe2+(aq) + O2 (g) + 4H+(aq) → 4Fe3+(aq) + 2H2O(l) 3. 4Fe3+(aq) + 12H2O(l) → 4Fe(OH)3 (s) + 12H+(aq) The 3 reactions combine to be: 4FeS2(s) + 15O2 (g) +14H2O(l) → 4Fe(OH)3 (s) + 8SO4-2(aq) + 16H+(aq) The first reaction involves pyrite rock reacting with oxygen (air) and water to produce dissolved ferrous iron, sulfate, and acidity. The second reaction oxidizes the dissolved ferrous iron in acidic conditions and produces ferric iron and water. The third reaction involves the hydrolysis of the ferric iron to form ferric hydroxide and more acid. The ferric hydroxide is the orangey-red colored solid you see in the water (Juniata College). Due to mines from the 1800s

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