TitleReal-Time Manganese Phase Dynamics during Biological and Abiotic Manganese Oxide Reduction.
Publication TypeJournal Article
AuthorsJohnson JE, Savalia P, Davis R, Kocar BD, Webb SM, Nealson KH, Fischer WW
JournalEnviron Sci Technol
Date2016 Apr 19
KeywordsBiodegradation, Environmental, Carbonates, Iron, Manganese, Manganese Compounds, Organometallic Compounds, Oxidation-Reduction, Oxides, Shewanella, Spectrum Analysis, Raman, Sulfides, Water, X-Ray Absorption Spectroscopy, X-Ray Diffraction

Manganese oxides are often highly reactive and easily reduced, both abiotically, by a variety of inorganic chemical species, and biologically during anaerobic respiration by microbes. To evaluate the reaction mechanisms of these different reduction routes and their potential lasting products, we measured the sequence progression of microbial manganese(IV) oxide reduction mediated by chemical species (sulfide and ferrous iron) and the common metal-reducing microbe Shewanella oneidensis MR-1 under several endmember conditions, using synchrotron X-ray spectroscopic measurements complemented by X-ray diffraction and Raman spectroscopy on precipitates collected throughout the reaction. Crystalline or potentially long-lived phases produced in these experiments included manganese(II)-phosphate, manganese(II)-carbonate, and manganese(III)-oxyhydroxides. Major controls on the formation of these discrete phases were alkalinity production and solution conditions such as inorganic carbon and phosphate availability. The formation of a long-lived Mn(III) oxide appears to depend on aqueous Mn(2+) production and the relative proportion of electron donors and electron acceptors in the system. These real-time measurements identify mineralogical products during Mn(IV) oxide reduction, contribute to understanding the mechanism of various Mn(IV) oxide reduction pathways, and assist in interpreting the processes occurring actively in manganese-rich environments and recorded in the geologic record of manganese-rich strata.

Alternate JournalEnviron. Sci. Technol.
PubMed ID27018915
Grant ListP41 GM103393 / GM / NIGMS NIH HHS / United States
P41GM103393 / GM / NIGMS NIH HHS / United States
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