水库析出物中显微针铁矿的成因差异——以湖北省富水水库及南河水库为例

CONTRAST OF CAUSES OF FORMATION OF MICRO-GOETHITE IN SEDIMENT FROM THE RESERVOIRS——TAKE FUSHUI AND NANHE RESERVOIRS FOR EXAMPLE

通过对湖北省富水、南河水库坝基渗漏水及其析出物的研究 ,探讨了不同水库沉积环境中显微针铁矿的成因差异及微生物在铁的生物矿化中的作用和意义。采用化学分析、X射线衍射、红外光谱、穆斯堡尔谱、透射电镜和扫描电镜分析等手段 ,研究了两个水库坝基渗漏水析出物的组成、物相和形貌特征。两个水库坝基渗漏水的成分相似 ,阳离子均以Ca2 + 、Mg2 + 、K+ 、Na+ 为主 ,Fe2 + 和Fe3 + 含量极少 ,阴离子以HCO-3 为主。渗漏水析出物的化学成分以铁的氧化物为主 ,析出物的主要矿物相为针铁矿、石英、伊利石、蒙脱石及微量方解石 ,呈弱结晶状态。穆斯堡尔谱图和SEM显微形貌特征证实了南河水库中针铁矿以化学成因为主 ,系菱铁矿风化而成 ;富水水库中针铁矿的形成受铁细菌的影响 ,以生物成因为主。

In this paper,the sediment from the percolating water in Fushui and Nanhe reservoirs in Hubei Province are studied,and the cause of formation of micro goethite in different reservoir environments, the action and the significance of microorganism in the mineralization of iron are discussed. The chemical component, mineral phase and configuration of the sediment from percolating water in the two reservoirs have been studied by ultimate analysis, X ray diffraction, Infrared spectroscopic analysis, Mossbauer spectrum, Transmission electron microscope (TEM) and scanning electron microscope (SEM). The percolating water of two reservoirs has the same composition, the main cations include Ca 2+ ?Mg 2+ ?K + and Na +,but contain minor Fe 2+ and Fe 3+ . The main anion is HCO - 3. The main chemical composition of the sediment from the percolating water is oxidized products of iron. And the main mineral phase includes goethite, quartz, illite, montmorillonite and little calcite. The study shows the difference of the causes of formation of micro-goethite in different environments by the characteristics of Mossbauer spectrum and microconfiguration from SEM: the goethite in sediment from Nanhe reservoir is the weathered product of siderite, while the goethite in sediment from Fushui reservoir is formed by ferrobacteria.