Submicron-Scale Heterogeneities in Nickel Sorption of Various Cell-Mineral Aggregates Formed by Fe(II)-Oxidizing Bacteria.
Submicron-Scale Heterogeneities in Nickel Sorption of Various Cell-Mineral Aggregates Formed by Fe(II)-Oxidizing Bacteria.
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DOI：
10.1021/acs.est.5b02955
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发表时间：
2016-01
影响因子：
11.4
通讯作者：
Gregor Schmid;Fabian Zeitvogel;L. Hao;Pablo Ingino;I. Adaktylou;M. Eickhoff;M. Obst
中科院分区：
文献类型：
--
作者：
Gregor Schmid;Fabian Zeitvogel;L. Hao;Pablo Ingino;I. Adaktylou;M. Eickhoff;M. Obst
Fe（II）氧化细菌形成由微生物细胞、胞外有机化合物和三价铁矿物组成的生物源细胞-矿物聚集体（CMA）。CMA能够通过吸附过程固定大量的重金属，例如镍。CMA对环境中重金属的归宿起着重要作用，特别是在以溶解金属浓度升高为特征的系统中，例如矿井排水或污染沉积物。我们采用扫描透射（软）X射线显微镜（STXM）光谱层析详细的三维化学映射吸附到CMA的亚微米尺度上的镍。我们分析了不同的CMA产生的光养或硝酸盐还原微生物Fe（II）氧化，此外，扭曲的茎结构从环境生物膜。镍表现出不均匀的分布，并被发现优先吸附到生物沉淀的铁矿物，如铁（III）-（oxyhydr）氧化物，并在较小程度上，与有机化合物。一些明显的镍积累被确定在CMA的表面上。从散点图和角距离图中获得的其他信息显示了镍-铁和镍-有机碳比率的变化，也揭示了镍和铁之间的一般相关性。虽然在2D图中观察到镍和铁之间的高度相关性，但3D图显示这部分是由于投影伪影。总之，通过结合不同的数据分析方法，我们明确地显示了镍对CMA的非均匀吸附行为。
Fe(II)-oxidizing bacteria form biogenic cell-mineral aggregates (CMAs) composed of microbial cells, extracellular organic compounds, and ferric iron minerals. CMAs are capable of immobilizing large quantities of heavy metals, such as nickel, via sorption processes. CMAs play an important role for the fate of heavy metals in the environment, particularly in systems characterized by elevated concentrations of dissolved metals, such as mine drainage or contaminated sediments. We applied scanning transmission (soft) X-ray microscopy (STXM) spectrotomography for detailed 3D chemical mapping of nickel sorbed to CMAs on the submicron scale. We analyzed different CMAs produced by phototrophic or nitrate-reducing microbial Fe(II) oxidation and, in addition, a twisted stalk structure obtained from an environmental biofilm. Nickel showed a heterogeneous distribution and was found to be preferentially sorbed to biogenically precipitated iron minerals such as Fe(III)-(oxyhydr)oxides and, to a minor extent, associated with organic compounds. Some distinct nickel accumulations were identified on the surfaces of CMAs. Additional information obtained from scatter plots and angular distance maps, showing variations in the nickel-iron and nickel-organic carbon ratios, also revealed a general correlation between nickel and iron. Although a high correlation between nickel and iron was observed in 2D maps, 3D maps revealed this to be partly due to projection artifacts. In summary, by combining different approaches for data analysis, we unambiguously showed the heterogeneous sorption behavior of nickel to CMAs.