Alteration of microbially precipitated iron oxides and hydroxides

Abstract

Other| December 01, 1998 Alteration of microbially precipitated iron oxides and hydroxides D. Ann Brown; D. Ann Brown University of Manitoba, Department of Geological Sciences, Winnipeg, MB, Canada Search for other works by this author on: GSW Google Scholar J. A. Sawicki; J. A. Sawicki Search for other works by this author on: GSW Google Scholar Barbara L. Sherriff Barbara L. Sherriff Search for other works by this author on: GSW Google Scholar Author and Article Information D. Ann Brown University of Manitoba, Department of Geological Sciences, Winnipeg, MB, Canada J. A. Sawicki Barbara L. Sherriff Publisher: Mineralogical Society of America First Online: 02 Mar 2017 Online ISSN: 1945-3027 Print ISSN: 0003-004X GeoRef, Copyright 2004, American Geological Institute. American Mineralogist (1998) 83 (11-12_Part_2): 1419–1425. https://doi.org/10.2138/am-1998-11-1231 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation D. Ann Brown, J. A. Sawicki, Barbara L. Sherriff; Alteration of microbially precipitated iron oxides and hydroxides. American Mineralogist 1998;; 83 (11-12_Part_2): 1419–1425. doi: https://doi.org/10.2138/am-1998-11-1231 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Iron oxide and hydroxides can be precipitated from solution with both Fe (super 2+) and Fe (super 3+) states by a microbial consortium enriched from surface water draining a granitic batholith. The Fe (super 2+) /Fe (super 3+) ratio of the microbial precipitate is determined by both the initial environment and subsequent diagenesis. To evaluate the thermal aspects of diagenesis, biological precipitates, either largely Fe (super 2+) or equally divided between Fe (super 2+) and Fe (super 3+) states, were heated at 80 degrees C for 12 weeks, under various redox conditions and compared to samples maintained under the same conditions at 4 degrees C. Mossbauer spectroscopy showed the iron oxide and hydroxides precipitated as Fe (super 2+) to be more stable than that as Fe (super 3+) . Only under air at 80 degrees C are the ferrous minerals altered to hematite, while the more labile ferric minerals are altered to Fe(OH) 2 at 4 degrees C and to hematite at 80 degrees C. In contrast, chemically precipitated Fe compounds, when incubated with the consortium, only form Fe (super 3+) compounds, mainly fine-grained hematite. When no microbes are present, goethite is formed during diagenesis. Fe speciation in sediments may reflect a combination of microbial mediation that causes the initial precipitation of iron oxides and hydroxides and the subsequent conditions of the diagenetic processes characteristic of that particular depositional environment. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.