Microbial reduction of structural Fe3+ in nontronite by a thermophilic bacterium and its role in promoting the smectite to illite reaction
American Mineralogist
By: G. Zhang, H. Dong, J. Kim, and D. D. Eberl
Links
- More information: Publisher Index Page (via DOI)
- Download citation as: RIS | Dublin Core
Abstract
The illitization process of Fe-rich smectite (nontronite NAu-2) promoted by microbial reduction of structural Fe3+ was investigated by using a thermophilic metal-reducing bacterium, Thermoanaerobacter ethanolicus, isolated from the deep subsurface. T. ethanolicus was incubated with lactate as the sole electron donor and structural Fe3+ in nontronite as the sole electron acceptor, and anthraquinone-2, 6-disulfonate (AQDS) as an electron shuttle in a growth medium (pH 6.2 and 9.2, 65 ??C) with or without an external supply of Al and K sources. With an external supply of Al and K, the extent of reduction of Fe3+ in NAu-2 was 43.7 and 40.4% at pH 6.2 and 9.2, respectively. X-ray diffraction and scanning and transmission electron microscopy revealed formation of discrete illite at pH 9.2 with external Al and K sources, while mixed layers of illite/smectite or highly charged smectite were detected under other conditions. The morphology of biogenic illite evolved from lath and flake to pseudo-hexagonal shape. An external supply of Al and K under alkaline conditions enhances the smectite-illite reaction during microbial Fe3+ reduction of smectite. Biogenic SiO2 was observed as a result of bioreduction under all conditions. The microbially promoted smectite-illite reaction proceeds via dissolution of smectite and precipitation of illite. Thermophilic iron reducing bacteria have a significant role in promoting the smectite to illite reaction under conditions common in sedimentary basins.
Suggested Citation
Zhang, G., Dong, H., Kim, J., Eberl, D.D., 2007, Microbial reduction of structural Fe3+ in nontronite by a thermophilic bacterium and its role in promoting the smectite to illite reaction: American Mineralogist, v. 92, no. 8-9, p. 1411-1419, https://doi.org/10.2138/am.2007.2498.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Microbial reduction of structural Fe3+ in nontronite by a thermophilic bacterium and its role in promoting the smectite to illite reaction |
| Series title | American Mineralogist |
| DOI | 10.2138/am.2007.2498 |
| Volume | 92 |
| Issue | 8-9 |
| Year Published | 2007 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | American Mineralogist |
| First page | 1411 |
| Last page | 1419 |