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Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Journal of Visualized Experiments
  • Markus Maisch, Iowa State University
  • Wenfang Wu, University of Tuebingen
  • Andreas Kappler, University of Tuebingen
  • Elizabeth D. Swanner, Iowa State University
Document Type
Article
Disciplines
Publication Version
Published Version
Publication Date
7-1-2016
DOI
10.3791/54251
Abstract

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling from hydrothermal sources in the Precambrian ocean was oxidized by molecular oxygen [O2] produced by cyanobacteria. The oldest BIFs, deposited prior to the Great Oxidation Event (GOE) at about 2.4 billion years (Gy) ago, could have formed by direct oxidation of Fe(II) by anoxygenic photoferrotrophs under anoxic conditions. As a method for testing the geochemical and mineralogical patterns that develop under different biological scenarios, we designed a 40 cm long vertical flow-through column to simulate an anoxic Fe(II)-rich marine upwelling system representative of an ancient ocean on a lab scale. The cylinder was packed with a porous glass bead matrix to stabilize the geochemical gradients, and liquid samples for iron quantification could be taken throughout the water column. Dissolved oxygen was detected non-invasively via optodes from the outside. Results from biotic experiments that involved upwelling fluxes of Fe(II) from the bottom, a distinct light gradient from top, and cyanobacteria present in the water column, show clear evidence for the formation of Fe(III) mineral precipitates and development of a chemocline between Fe(II) and O2. This column allows us to test hypotheses for the formation of the BIFs by culturing cyanobacteria (and in the future photoferrotrophs) under simulated marine Precambrian conditions. Furthermore we hypothesize that our column concept allows for the simulation of various chemical and physical environments — including shallow marine or lacustrine sediments.

Comments

This article is from J. Vis. Exp. (113), e54251, doi:10.3791/54251 (2016). Posted with permission.

Copyright Owner
Journal of Visualized Experiments
Language
en
File Format
application/pdf
Citation Information
Markus Maisch, Wenfang Wu, Andreas Kappler and Elizabeth D. Swanner. "Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria" Journal of Visualized Experiments Vol. 113 (2016) p. e54251
Available at: http://works.bepress.com/elizabeth_swanner/2/