科研之友
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摘要
Fe(III)-oxyhydroxysulfate minerals are ubiquitous in sediments in rivers contaminated by acid mine drainage (AMD), and considered as scavengers for heavy metals. The reduction of these minerals by sulfate reducing bacteria destroys the stability of minerals and causes the release of coprecipitated contaminants. Previous researches had found Citrobacter sp. existed in the AMD sediment with a high sulfate reduction ability under reducing condition. Therefore, it is crucial to explore the reduction and dissolution of Fe(III)-oxyhydroxysulfate minerals and the transformation behavior of mineral crystalline phase by Citrobacter sp.. In this study, schwertmannite and jarosite, the typical Fe(III)-oxyhydroxysulfate minerals, were selected to investigate the effect of Citrobacter sp. EBS8 on the reductive dissolution and mineral phase transformation under laboratory conditions. The results showed that both schwertmannite and jarosite dissolved and had phase transformation in anoxic, neutral and sufficient electron donor systems. Strain EBS8 could reduce SO42- and Fe(III) by using lactate as electron donor. Scanning electron micrograph (SEM) further showed that the surface burr of schwertmannite appeared in the initial phase, and jarosite was dissolved layer by layer from the outside to the inside, and then appeared morphology of the empty shell. The main transformation products of schwertmannite were siderite and vivianite, while jarosite was transformed into vivianite and mackinawite. The present study helps to understand the transformation behavior of Fe(III)-oxyhydroxysulfate minerals and provide theoretical support for remediation of AMD-contaminated environment.
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