Submicron-Scale Heterogeneities in Nickel Sorption of Various Cell-Mineral Aggregates Formed by Fe(II)-Oxidizing Bacteria
| Autor: | Gregor Schmid, Merle Eickhoff, Fabian Zeitvogel, Martin Obst, Irini J. Adaktylou, Pablo Ingino, Likai Hao |
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| Rok vydání: | 2015 |
| Předmět: |
0301 basic medicine
Mineral Phototroph Bacteria 030106 microbiology Metallurgy Biofilm chemistry.chemical_element Sorption General Chemistry 010501 environmental sciences 01 natural sciences Ferrous Compounds 03 medical and health sciences Nickel Adsorption chemistry Environmental chemistry Oxidizing agent Environmental Chemistry Oxidation-Reduction 0105 earth and related environmental sciences |
| Zdroj: | Environmental sciencetechnology. 50(1) |
| ISSN: | 1520-5851 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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