Journal article
Oxygen Isotope Evidence for Mn(II)-Catalyzed Recrystallization of Manganite (γ-MnOOH)
Environmental science & technology, Vol.50(12), pp.6374-6380
06/21/2016
DOI: 10.1021/acs.est.6b01463
PMID: 27249316
Abstract
Manganese is biogeochemically cycled between aqueous Mn(II) and Mn(IV) oxides. Aqueous Mn(II) often coexists with Mn(IV) oxides, and redox reactions between the two (e.g., comproportionation) are well known to result in the formation of Mn(III) minerals. It is unknown, however, whether aqueous Mn(II) exchanges with structural Mn(III) in manganese oxides in the absence of any mineral transformation (similar to what has been reported for aqueous Fe(II) and some Fe(III) minerals). To probe whether atoms exchange between a Mn(III) oxide and water, we use a (17)O tracer to measure oxygen isotope exchange between structural oxygen in manganite (γ-MnOOH) and water. In the absence of aqueous Mn(II), about 18% of the oxygen atoms in manganite exchange with the aqueous phase, which is close to the estimated surface oxygen atoms (∼11%). In the presence of aqueous Mn(II), an additional 10% (for a total of 28%) of the oxygen atoms exchange with water, suggesting that some of the bulk manganite mineral (i.e., beyond surface) is exchanging with the fluid. Exchange of manganite oxygen with water occurs without any observable change in mineral phase and appears to be independent of the rapid Mn(II) sorption kinetics. These experiments suggest that Mn(II) catalyzes manganese oxide recrystallization and illustrate a new pathway by which these ubiquitous minerals interact with their surrounding fluid.
Details
- Title: Subtitle
- Oxygen Isotope Evidence for Mn(II)-Catalyzed Recrystallization of Manganite (γ-MnOOH)
- Creators
- Andrew J Frierdich - Monash UniversityMichael J Spicuzza - University of Wisconsin–MadisonMichelle M Scherer - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Environmental science & technology, Vol.50(12), pp.6374-6380
- DOI
- 10.1021/acs.est.6b01463
- PMID
- 27249316
- ISSN
- 0013-936X
- eISSN
- 1520-5851
- Grant note
- DOI: 10.13039/100000160, name: Division of Earth Sciences, award: 1123978, 1347848
- Language
- English
- Date published
- 06/21/2016
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9984197090802771
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