EAGER -- Field tests of low-impact treatment for acid mine drainage

这一探索性项目将研究能够刺激自然微生物过程以扭转酸性矿山排水条件的现场技术。当采矿作业中开采的硫化物矿物暴露在地球表面的氧化和水解中时，就会产生酸性矿山废水。然而，在这些矿场的土壤和溪流沉积物中，有一个微生物群落，主要是硫酸盐还原细菌和铁还原细菌，它们有能力扭转受影响水域典型的低pH值和重金属含量升高的状况。将在马萨诸塞州西部长期废弃的黄铁矿Davis矿的出水口建立一个实地研究地点，以监测由于向出水口引入活性填充物而导致的地球化学变化。这种活性填充物将由石灰石和有机堆肥的混合物组成，它将提供酸性水的初始中和和碳源，以刺激微生物种群。将定期在实验场的上游和下游收集水样，以监测引入混合物后产生的化学变化。如果注意到持续的积极变化，将对引入活性填料之前和之后的水系沉积物中的微生物群落进行分析。调查结果将提供有关就地铁和硫酸盐还原细菌成功生长和发展所需条件的重要数据，这些条件有助于长期逆转产酸和金属运输。酸性矿山排水(AMD)是一个全球性问题，通常与大规模的煤炭开采有关，但它经常发生在偏远地区废弃的贱金属矿山周围。清理这些地点往往涉及复杂的工程工作，既耗资巨大，又破坏环境。然而，如果能够改变受影响矿场地表水域的条件，使硫酸盐和铁还原细菌的自然群落能够生长和繁荣，这些微生物就可以建立一种自我维持的方法，来中和多余的酸度和去除金属。这个项目将研究能够优化条件以实现这样一个有益结果的过程。

This exploratory project will investigate field techniques by which natural microbial processes can be stimulated to reverse the conditions of acid-mine drainage. Acid-mine drainage is produced when sulfide minerals excavated during mining operations are exposed to oxidation and hydrolysis at the Earth's surface. However, within the soils and stream deposits of these mine sites there is a community of microorganisms, largely sulfate-reducing and iron-reducing bacteria, that have the capability of reversing the conditions of low pH and elevated heavy metal content typical of affected waters. A field study site will be established at the outflow of Davis Mine, a long-abandoned pyrite mine in western Massachusetts, to monitor the changes in geochemistry that result from the introduction of a reactive fill into the outflow. This reactive fill will consist of a mix of limestone and organic compost that will provide an initial neutralization of the acidic water and a carbon source to stimulate the microbial population. Water samples will be collected at regular intervals upstream and downstream of the experiment site to monitor changes in chemistry resulting from the introduction of the mixture. If persistent positive changes are noted, the microbial communities within the stream sediments both before and after introduction of the reactive fill will be assayed. The results of the investigation will provide important data on the conditions required for successful growth and development of the in situ iron- and sulfate-reducing bacteria that can help in a long-term reversal of acid generation and metal transport. Acid-mine drainage (AMD) is a global problem that is often associated with extensive coal mining, but it occurs frequently around abandoned base-metal mines in remote areas. Cleaning up these sites often involves elaborate engineering efforts that are both costly and environmentally disruptive. However, if the conditions within the surface waters of an affected mine site can be modified so that the natural community of sulfate- and iron-reducing bacteria can grow and prosper, these microorganisms could establish a self-sustaining method for neutralizing the excess acidity and removing the metals. This project will examine the processes that can optimize the conditions for such a beneficial outcome.