Show simple item record

dc.contributor.authorRibeiro, Fabiana R.en_US
dc.contributor.authorFabris, José D.en_US
dc.contributor.authorKostka, Joel E.en_US
dc.contributor.authorKomadel, Peteren_US
dc.contributor.authorStucki, Joseph W.en_US
dc.date.accessioned2011-12-23T17:50:12Z
dc.date.available2011-12-23T17:50:12Z
dc.date.issued2009-07
dc.identifier.citationRibeiro, F.R., J.D. Fabris, J. E. Kostka, P. Komadel, and J. W. Stucki. 2009. Comparisons of Structural Iron Reduction in Smectites by Bacteria and Dithionite: II. A variable-temperature Mössbauer spectroscopic study of Garfield nontronite. Pure and Applied Chemistry 81: 1499-1509.en_US
dc.identifier.issn0033-4545
dc.identifier.urihttp://hdl.handle.net/1853/42115
dc.description© 2009 IUPACen_US
dc.descriptionDOI: 10.1351/PAC-CON-08-11-16en_US
dc.description.abstractThe reduction of structural Fe in smectite may be mediated either abiotically by reaction with chemical reducing agents or biotically by reaction with various bacterial species. The effects of abiotic reduction on clay surface chemistry are much better known than the effects of biotic reduction, and differences between them are still in need of investigation. The purpose of the present study was to compare the effects of dithionite (abiotic) and bacteria (biotic) reduction of structural Fe in nontronite on the clay structure as observed by variabletemperature Mössbauer spectroscopy. Biotic reduction was accomplished by incubating Na-saturated Garfield nontronite (sample API 33a) with Shewanella oneidensis strain MR-1 (FeII/total Fe achieved was ~17 %). Partial abiotic reduction (FeII/total Fe ~23 %) was achieved using pH-buffered sodium dithionite. The nontronite was also reduced abiotically to FeII/total Fe ~96 %. Parallel samples were reoxidized by bubbling O2 gas through the reduced suspensions at room temperature prior to Mössbauer analysis at 77 and 4 K. At 77 K, the reduction treatments all gave spectra composed of doublets for structural FeII and FeIII in the nontronite. The spectra for reoxidized samples were largely restored to that of the un - altered sample, except for the sample reduced to 96 %. At 4 K, the spectrum for the 96 % reduced sample was highly complex and clearly reflected magnetic order in the sample. When partially reduced, the spectrum also exhibited magnetic order, but the features were completely different depending on whether reduced biotically or abiotically. The biotically reduced sample appeared to contain distinctly separate domains of FeII and FeIII within the structure, whereas partial abiotic reduction produced a spectrum representative of FeII–FeIII pairs as the dominant domain type. The 4 K spectra of the partially reduced, fully reoxidized samples were virtually the same as at 77 K, whereas reoxidation of the 96 % reduced sample produced a spectrum consisting of a magnetically ordered sextet with a minor contribution from a FeII doublet, indicating significant structural alterations compared to the un - altered sample.en_US
dc.language.isoen_USen_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectRedoxen_US
dc.subjectReductionen_US
dc.subjectOxidationen_US
dc.subjectCyclesen_US
dc.subjectNontroniteen_US
dc.subjectBacteriaen_US
dc.subjectShewanellaen_US
dc.titleComparisons of Structural Iron Reduction in Smectites by Bacteria and Dithionite: II. A variable-temperature Mössbauer spectroscopic study of Garfield nontroniteen_US
dc.typeArticleen_US
dc.contributor.corporatenameGeorgia Institute of Technology. School of Biologyen_US
dc.contributor.corporatenameUniversity of Illinois at Urbana-Champaign. Dept. of Natural Resources and Environmental Sciencesen_US
dc.contributor.corporatenameUniversidade Federal de Minas Geraisen_US
dc.contributor.corporatenameFlorida State University. Dept. of Chemistryen_US
dc.contributor.corporatenameSlovenská akadémia vieden_US
dc.publisher.originalInternational Union of Pure and Applied Chemistryen_US
dc.identifier.doi10.1351/PAC-CON-08-11-16


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record