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The outflow of acidic liquids and other pollutants from mines is often catalysed by acid-loving microorganisms; these are the acidophiles in acid mine drainage. Acidophiles are not just present in exotic environments such as Yellowstone National Park or deep-sea hydrothermal vents. Genera such as Acidithiobacillus and Leptospirillum bacteria, and Thermoplasmatales archaea, are present in syntrophic relationships in the more mundane environments of concrete sewer pipes and implicated in the heavy-metal-containing, sulfurous waters of rivers such as the Rheidol. Such microorganisms are responsible for the phenomenon of acid mine drainage (AMD) and thus are important both economically and from a conservation perspective. Control of these acidophiles and their harnessing for industrial biotechnology shows their effect need not be entirely negative. The use of acidophilic organisms in mining is a new technique for extracting trace metals through bioleaching, and offers solutions for the phenomenon of acid mine drainage in mining spoils. ==Introduction== Upon exposure to oxygen (O2) and water (H2O), metal sulfides undergo oxidation to produce metal-rich acidic effluent. If the pH is low enough to overcome the natural buffering capacity of the surrounding rocks (‘calcium carbonate equivalent’ or ‘acid neutralising capacity’), the surrounding area may become acidic, as well as contaminated with high levels of heavy metals. Though acidophiles have an important place in the iron and sulfur biogeochemical cycles, strongly acidic environments are overwhelmingly anthropogenic in cause, primarily created at the cessation of mining operations where sulfide minerals, such as pyrite (iron disulfide or FeS2), are present.〔 Acid mine drainage may occur in the mine itself, the spoil heap (particularly colliery spoils from coal mining), or through some other activity that exposes metal sulfides at a high concentration, such as at major construction sites. Banks ''et al.''〔 provide a basic summary of the processes that occur: :2FeS2 + 2H2O + 7O2 = 2Fe2+ + 4SO42− + 4H+(aq) :Pyrite + water + oxygen = ferrous iron + sulfate + acid 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Acidophiles in acid mine drainage」の詳細全文を読む スポンサード リンク
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