Acid Mine Drainage (AMD)

Acid Mine Drainage Outflow of acidic water, usually from abandoned coal mines Old mine fills up with water Heavy metals get into the water (pyrite – iron sulfide) Forms sulfuric acid and dissolved iron When water comes in contact with air it oxidizes the iron and turns orange

AMD in Pa Pa has relatively high amounts of AMD b/c of the high number of coal mines Mostly in Western PA Also in West Virgina, Ohio, etc http://www.youtube.com/watch?v=il0UOMa-WPA http://www.youtube.com/watch?v=GR1saXGRezc

Effects Lowers pH of the stream – usually ph of 5 or below Effects growth / reproduction of aquatic plants and aquatic organism (like macroinvertebrates) Effects fish populations In drinking water can cause birth defects Effects recreation and tourism

Treatments Active Treatment Passive Treatment Add basic substances to the water to try to neutralize the acidity Passive Treatment Construct wetlands – add neutralized water and allow heavy metals to precipitate out http://www.youtube.com/watch?v=6ZHpPynNokM

Causes… AMD occurs when the pyrite iron sulfide from the coal becomes exposed and reacts with both the water from the stream and oxygen, causing dissolved iron and sulfuric acid to form. The rate and extent to which it forms varies depending on certain bacteria.

Effects? The yellow/orange discoloration in the streams harms ecosystems because it smothers the animal and plant life and increases the pH levels. Because of the highly toxic levels of acidity, left over metals, and sediments all animal life in the streams die.

AMD In Pennsylvania… Because of all the abandoned coal mines, more than 3,000 miles of streams are contaminated in PA. It is the most extensive water pollution problem in the four major rivers in PA. PA loses 67 million a year in treatment of the contaminations.

Active Treatment Pros & Cons: Is a great to raise pH levels and reduce the presence of metals. Cons: Lime, soda ash, and ammonia are very expensive to maintain Disposal of metal loaded waste can be a problem.

Passive Treatment Passive treatment has been used since early 1990’s. It uses a variety of treatment to raise pH levels.

Passive Treatment Pros & Cons: It needs only periodic maintenance Lower costs than Active Treatment Cons: not enough land