摘要
微生物介导的铁循环是调控地表有害物质迁移转化等地球化学反应的关键因子之一。为了探明腐殖酸对微生物还原含铁黏土矿物的影响,选取了富铁黏土矿物绿脱石和不同土壤中提取到的腐殖酸为研究对象进行了实验,在有、无腐殖酸2种条件下对比了典型异化铁还原菌Shewanella putrefaciens CN32对绿脱石结构Fe(Ⅲ)的还原效率,同时分析了微生物作用后绿脱石的晶体结构差异。实验采用化学方法检测Fe(Ⅲ)的还原程度,利用X射线粉晶衍射(XRD)及傅里叶转换红外光谱(FT-IR)对微生物作用前后的绿脱石进行了矿物学表征,利用扫描电镜(SEM)研究了反应前后绿脱石的形貌差异。实验结果表明不同来源的腐殖酸均具有促进微生物还原绿脱石结构Fe(Ⅲ)的能力,但其促进效率存在差异。绿脱石中的结构Fe(Ⅲ)经微生物还原后,其矿物结构被破坏,结晶程度逐渐降低,矿物形貌由不规则片状变为松散疏松的网絮状。本研究对深入理解自然环境中铁的生物地球化学循环及其环境效应具有启示意义。
Microbially-mediated iron redox cycling profoundly impacts surficial geochemical reactions, such as the transport and transformation of hazardous substances. The objective of this study is to study the influence of humic acid on microbial reduction of Fe（Ⅲ）-containing clay mineral. A series of abiotic and biotic experiments were conducted, in which nontronite （iron-rich smectite） as the Fe（Ⅲ） source, and a typical dissimilatory iron-reducing bacterium Shewanella putrefaciens CN32 as the reaction mediator with or without humic acids. The Fe（Ⅲ） reduction extent was monitored via wet chemistry, and the mineralogical changes of nontronite were characterized by X-ray diffraction （XRD）, Fourier transformation infrared spectroscopy （FT-IR） and scanning electron microscopy （SEM）. The results indicate that humic acids from different natural sources significantly promote the microbial reduction extent, but the enhancement efficiency is different among them. Mineralogical analysis demonstrates that nontronite structural collapsed upon microbial iron reduction, and its morphology was changed from irregular flake to filament texture. These results have important implications for understanding iron biogeochemistry and its environmental effects in nature.
出处
《地质科技情报》
CAS
CSCD
北大核心
2016年第6期205-211,共7页
Geological Science and Technology Information
基金
国家自然科学基金项目(41302270)
