Caractéristiques physico-chimiques du vieillissement des oxydes de fer biogéniques formés à la surface de différentes bactéries.

Abstract

This laboratory study was undertaken to investigate the natural mechanisms of Fe-oxide formation onto bacteria and their ageing under laboratory conditions simulating the natural aquatic environment. Fe-oxides were formed the oxidation of Fe(II) at pH 5.75 at two different Fe concentrations (i.e. 10-5 M and 10-4M) in the presence of four different bacterial strains (Escherichia coli, Bacillus subtilis, Bacillus licheniformis and Pseudomonas aeruginosa). Various dissolved species (SO4 (10-4M), PO 4 (10-5M), Al (10-7 M) and Si (10-3M)) were also added to the systems in order to assess their role on the formation and ageing of biogenic Fe-oxides. All systems were left in the dark at 4°C for a period of six months to simulate lake diagenesis. Abiotic systems were formed under identical conditions for further comparisons. Each month, a filtered aliquot of each system was analyzed for its content in dissolved Fe, SO4, PO4 and Si, and for pH and Eh. Sub-samples were also taken for transmission electron microscopy (TEM) observations and X-ray diffraction. (Abstract shortened by UMI.)