Microbially-mediated Sulfide Mineral Dissolution: Biogeochemical Controls on Reactions at Pyrite Surfaces

环境地球化学和生物地球化学项目的这一奖项由地球科学部和化学部共同支持。威斯康星大学麦迪逊分校地质系的Jillian F.Banfield博士和化学系的Robert J.Hamers博士将研究微生物对黄铁矿表面的影响。大量的生物(细菌和古菌)已经被证明附着在黄铁矿上，并出现在黄铁矿溶解产生的低pH溶液中。然而，对附着生物体对黄铁矿溶解的直接生物催化作用的机理知之甚少，对附着和非附着Fe和S氧化生物体分布的地球化学控制也是如此。在这项研究中，化石菌的丰度和分布将作为pH、离子强度和地化条件的函数进行研究。生物体的附着位置将与表面形态相关，使用预先确定的表面和培养的微生物以及自然环境中的微生物。将在低pH值下研究微生物附着在黄铁矿上的聚合物结合层，并确定其与黄铁矿溶解的关系。结果将与酸性矿山废水产生的现场研究的动力学数据进行比较。实验将受到有关现场相关物种的分子生物学信息和固-液-有机界面的物理和化学细节的限制。细菌在酸性矿山废水中的作用还不是很清楚。直到最近，在铁山(加利福尼亚州雷丁)等地的硫化铁(黄铁矿)溶解模型中只考虑了化学和地质因素。一些与铁黄铁矿溶解有关的细菌的鉴定已经在以前的工作中确定了。这里将确定细菌在金属硫化物溶解中的作用。本课程将探讨细菌如何附着在矿物表面以及这种附着如何影响金属运输等因素。

This award in the Environmental Geochemistry and Biogeochemistry Program is jointly supported by the Divisions of Earth Sciences and Chemistry. Drs. Jillian F. Banfield, Geology Department, and Robert J. Hamers, Chemistry Department, of the University of Wisconsin-Madison will investigate effects of microbes on pyrite surfaces. Abundant organisms (bacteria and archaea) have been shown to attach to pyrite and to occur in the low pH solutions produced by pyrite dissolution. The mechanism of `direct` biological catalysis of pyrite dissolution involving attached organisms is poorly understood, however, as are the geochemical controls on the distribution of attached and non-attached Fe and S oxidizing organisms. In this research, the abundance and distribution of chemolithotrophs will be studied as a function of pH, ionic strength and geochemical conditions. Attachment sites for organisms will be correlated with surface morphology using precharacterized surfaces and cultured microbes as well as microbes in the natural environment. The polymeric binding layer whereby microbes attach to pyrite will be studied at low pH and the relationship to pyrite dissolution determined. The results will be compared to kinetic data from field studies of acid mine drainage generation. Experiments will be constrained by both molecular biological information about the relevant species at the site and physical and chemical details of the solid-liquid-organic interfaces. The role of bacteria in acid mine drainage is not well understood. Until recently, only chemical and geological factors were considered in models for dissolution of iron sulfides (pyrite) at locations such as Iron Mountain (Redding, California). The identify of some bacteria associated with iron pyrite dissolution was determined in previous work. Here the role of bacteria in dissolution of the metal sulfides will be determined. Factors such as how bacteria attach to mineral surfaces and how transport of metals is affected by that attachment will be explored