我国北西部地区层间氧化带砂岩型铀矿床微生物与铀成矿作用研究初探

Relationship between Micro-organisms and Uranium Metallogeny of the Interlayer Oxidation Zone Sandstone-Type Uranium Deposits in NW China

层间氧化带砂岩型铀矿床中微生物参与成矿现象和微生物活动证据越来越多,表明微生物对当今我国主攻的层间氧化带砂岩型铀矿床的形成起重要作用。本文利用分子生物学、活菌培养和实验室模拟等方法对新疆十红滩和蒙其古尔两个典型砂岩型铀矿床中微生物与铀成矿作用关系进行了探讨,结果表明不同地球化学环境带岩石中主要微生物类群的分布特征不同,表现出明显的生物地球化学分带性,从氧化带到还原带,喜氧菌数量逐渐减少,厌氧菌数量递增,各带细菌的分布受容矿层中有机碳含量、铁的存在形式及含量、所赋存地下水的溶解氧和硫酸盐含量等的控制。微生物对铀成矿的影响是综合性的,同时也受到各种环境因素的制约,微生物之间也存在着共生、互生、竞争和拮抗的关系,从而影响着矿床的发育。该类铀矿床微生物富集铀的机制是以间接的非代谢性生物吸附为主,而代谢性富集机制则是次要的。

There are increasing evidence showing that microorganisms in interlayer oxidation zone sandstone type uranium deposit have involved in uranium metallogeny, indicating that China should focus on study of important role of microorganisms in the formation of interlayer oxidation zone sandstone type uranium deposits. Through molecular biology, living bacterium cultivating and laboratory simulation method, this study discussed microbial relationship with uranium mineralization in the Shihongtan and Mengqiguer sandstone type uranium deposits of Xinjiang. The results show that the microbial groups have different distribution characteristics in the different geochemical environments and present distinct biogeochemical zonation. From oxidation to reduction zones, the number of anaerobic bacteria increases while the number of aerobic bacteria number decreases. The distribution of bacteria in each zone is controlled by organic carbon content, iron occurrence and content and dissolved oxygen and sulphate content in groundwater. Microbial effects on uranium mineralization are comprehensive and restricted by various environmental factors. There are kinds of relationship occurring in microorganism, such as symbiosis and mutualism, and competition and antagonism, all of which affect the development of uranium deposits. The microorganism enrichment mechanism of uranium deposits is dominated by indirect metabolic biosorption, followed by enrichment of metabolic mechanism.