Citrobacter sp.EBS8对施氏矿物和黄钾铁矾的还原溶解及相转化行为的影响

铁硫酸盐次生矿物广泛存在于酸性矿山废水（AMD）污染流域沉积物中，是多种有毒有害重金属的沉淀库.硫酸盐还原菌对矿物的还原作用可破坏矿物的稳定性从而引起共沉淀重金属的释放.在前期研究中发现柠檬酸杆菌Citrobacter sp.存在于AMD流域沉积物中，且在还原条件下具有较强的硫酸盐还原能力.因此，探究其对铁硫次生矿物的还原溶解及矿物晶相转化行为的影响尤为重要.本研究选取矿区沉积物中典型的铁硫次生矿物施氏矿物和黄钾铁矾为研究对象，在实验室条件下考察了从AMD污染沉积物中筛选到的菌株Citrobacter sp.EBS8对矿物的还原溶解及相转化的影响.结果表明，在缺氧、中性pH及电子供体足量时，在EBS8的作用下施氏矿物和黄钾铁矾均出现了明显的还原溶解现象.菌株EBS8可利用乳酸盐作为电子供体还原SO₄^2-和Fe（III）.SEM结果显示，施氏矿物在反应初期出现表面毛刺不平现象，黄钾铁矾发生由外向内的逐层溶解，矿物转化过程中都出现空壳形貌.XRD检测到施氏矿物组的主要转化产物为菱铁矿和蓝铁矿，黄钾铁矾体系中主要是蓝铁矿和马基诺矿.这些结果有助于了解AMD污染沉积物中铁硫酸盐矿物的转化行为及为AMD污染治理提供理论支撑.

Effects of Citrobacter sp. EBS8 on reductive dissolution and phase transformation behaviors of schwertmannite and jarosite

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 SO₄^2- 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.