Reductive immobilization of Cr(VI) has been widely explored as a cost-effective approach for Cr-contaminated site remediation. In soils containing manganese oxides, however, the immobilized form of chromium, i.e., Cr(III), could potentially be reoxidized. In this study, batch experiments
were conducted to assess whether there were any microbial processes that could accelerate Cr(III) oxidation in aerobic, manganese-containing systems. The results showed that in the presence of at least one species of manganese oxidizers, Pseudomonas putida , Cr(III) oxidation took place at
low concentrations of Cr(III). About 30–50% of added Cr(III) (10–200 µ M) was oxidized to Cr(VI) within five days in the systems with P. putida and biogenic Mn oxides. The rate of Cr(III) oxidation was approximately proportional to the initial concentration of Cr(III) up
to 100 µ M, but the growth of P. putida was partially inhibited by Cr(III) at 200 µ M and totally stopped when it reached 500 µ M. Cr(III) oxidation was dependent upon the biogenic formation of Mn oxides, though the oxidation rate was not directly proportional to the amount
of Mn oxides formed. Chromium(III) oxidation took place through a catalytic pathway, in which the microbes mediated Mn(II) oxidation to form Mn-oxides, and Cr(III) was subsequently oxidized by the biogenic Mn-oxides.
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Document Type: Research Article
Department of Civil & Environmental Engineering, University of Missouri, Columbia, Missouri, 65211, USA
Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin, 53706, USA
Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, 87131, USA
Publication date: 2005-04-01
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