Biogenic iron mineralization accompanying the dissimilatory reduction of hydrous ferric oxide by a groundwater bacterium

Details Biogenic iron mineralization accompanying the dissimilatory reduction of hydrous ferric oxide by a groundwater bacterium Biogenic iron mineralization accompanying the dissimilatory reduction of hydrous ferric oxide by a groundwater bacterium

Oct 1998

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998gecoa..62.3239f&link_type=abstract

Geochimica et Cosmochimica Acta, vol. 62, Issue 19-20, pp.3239-3257

Computer Science

42

Scientific paper

Dissimilatory iron-reducing bacteria (DIRB) couple the oxidation of organic matter or H 2 to the reduction of iron oxides. The factors controlling the rate and extent of these reduction reactions and the resulting solid phases are complex and poorly understood. Batch experiments were conducted with amorphous hydrous ferric oxide (HFO) and the DIRB Shewanella putrefaciens , strain CN32, in well-defined aqueous solutions to investigate the reduction of HFO and formation of biogenic Fe(II) minerals. Lactate-HFO solutions buffered with either bicarbonate or 1,4-piperazinediethanesulfonic acid (PIPES) containing various combinations of phosphate and anthraquinone-2,6-disulfonate (AQDS), were inoculated with S. putrefaciens CN32. AQDS, a humic acid analog that can be reduced to dihydroanthraquinone by CN32, was included because of its ability to function as an electron shuttle during microbial iron reduction and as an indicator of pe. Iron reduction was measured with time, and the resulting solids were analyzed by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). In HCO 3 - buffered medium with AQDS, HFO was rapidly and extensively reduced, and the resulting solids were dominated by ferrous carbonate (siderite). Ferrous phosphate (vivianite) was also present in HCO 3 - medium containing P, and fine-grained magnetite was present as a minor phase in HCO 3 - medium with or without P. In the PIPES-buffered medium, the rate and extent of reduction was strongly influenced by AQDS and P. With AQDS, HFO was rapidly converted to highly crystalline magnetite whereas in its absence, magnetite mineralization was slower and the final material less crystalline. In PIPES with both P and AQDS, a green rust type compound [Fe (6-x) II Fe x III (OH) 12 ] x+ [(A 2- ) x/2 · yH 2 O] x- was the dominant solid phase formed; in the absence of AQDS a poorly crystalline product was observed. The measured pe and nature of the solids identified were consistent with thermodynamic considerations. The composition of aqueous media in which microbial iron reduction occurred strongly impacted the rate and extent of iron reduction and the nature of the reduced solids. This, in turn, can provide a feedback control mechanism on microbial metabolism. Hence, in sediments where geochemical conditions promote magnetite formation, two-thirds of the Fe(III) will be sequestered in a form that may not be available for anaerobic bacterial respiration.

Affiliated with

Also associated with

No associations

Rating

Biogenic iron mineralization accompanying the dissimilatory reduction of hydrous ferric oxide by a groundwater bacterium does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Biogenic iron mineralization accompanying the dissimilatory reduction of hydrous ferric oxide by a groundwater bacterium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Biogenic iron mineralization accompanying the dissimilatory reduction of hydrous ferric oxide by a groundwater bacterium will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1721213