Title
Quantitative charge state analysis of manganese biominerals in aqueous suspension using Scanning Transmission X-ray Microscopy (STXM)
Abbreviated Journal Title
Geochim. Cosmochim. Acta
Keywords
TRANSITION-METAL COMPOUNDS; ADVANCED LIGHT-SOURCE; MARINE BACILLUS SP; ABSORPTION-SPECTROSCOPY; MATERIALS SCIENCE; OXIDATION-STATE; STRAIN; SG-1; SPORE COATS; MN; SPECTROMICROSCOPY; Geochemistry & Geophysics
Abstract
We have applied Scanning Transmission Soft X-ray Microscopy (STXM) to investigate the charge state distribution of Mn in two kinds of Mn-biominerals, Mn nodules collected from Lake Michigan sediments and Mn precipitates formed by spores of a marine bacillus SG-1 under transport limited reaction conditions. A data analysis technique was developed, which allows for extraction of spatially resolved 2-d charge state maps of manganese on a submicron level. We find that the charge state of Mn dominates the spectral shape of L-edge spectra of environmentally important single oxidation state Mn minerals and that spectra of mixed oxidation state oxides can be modelled by a combination of appropriate single oxidation state reference spectra. Two-dimensional maps of charge state distributions clearly reveal domains of different oxidation states within single particles of Mn-micronodules. Spots of preferred accumulation of Mn(II) were found, which indicates biogenic precipitation of Mn(Il)-species as a first step of nodule formation. The presence of Mn(III) in the studied sediment samples suggests the involvement of one-electron oxidation processes and reaction conditions which inhibit or slow down the disproportionation of Mn(Ill)-products. Under transport limited conditions, Mn oxidation products formed by spores of the marine bacillus SG-1 can vary from cell to cell. The presence of significant amounts of Mn(III) containing species points to the involvement of one-electron oxidation reactions as in the case of the micro-nodules. Our technique and the results obtained form a new basis for the mechanistic understanding of the formation of Mn biominerals in the environment. Copyright (C) 2003 Elsevier Science Ltd.
Journal Title
Geochimica Et Cosmochimica Acta
Volume
67
Issue/Number
6
Publication Date
1-1-2003
Document Type
Article
Language
English
First Page
1089
Last Page
1098
WOS Identifier
ISSN
0016-7037
Recommended Citation
"Quantitative charge state analysis of manganese biominerals in aqueous suspension using Scanning Transmission X-ray Microscopy (STXM)" (2003). Faculty Bibliography 2000s. 3956.
https://stars.library.ucf.edu/facultybib2000/3956
Comments
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