Elucidating Biogeochemical Reduction of Chromate via Carbon Amendments and Soil Sterilization

Sterilized and non-sterilized soil columns were amended with three different carbon sources to elucidate the potential for geochemical and biological Cr⁶⁺ reduction. Cr⁶⁺ was reduced to Cr³⁺ in the non-sterilized lactate, ethanol, and acetate-amended soils; however, soils amended with lactate reduced significantly more chromium. Soils sterilized by γ-irradiation reduced almost no Cr⁶⁺, indicating that Cr⁶⁺ reduction was at least indirectly biological in nature. Analyses of small subunit (ssu) rRNA genes amplified from the column sediments showed significantly different bacterial populations within the amended soils that may be due to carbon source or to aerobic micropockets within the sediment columns.

Keywords:

• bioremediation
• hexavalent chromium
• metal reduction
• soil sterilization
• reduction potential

Current address for Ginder-Vogel is Department of Plant and Soil Sciences, University of Delaware.

This research was sponsored by the Natural and Accelerated Bioremediation Research (NABIR) program of the U.S. Department of Energy (DOE). Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR2272. A portion of this work was conducted at Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. The SSRL Structural Molecular Biology Program is supported by the Department of Energy, Office of Biological and Environmental Research, and by the National Institutes of Health, National Center for Research Resources, Biomedical Technology Program. Tonia Mehlhorn assisted in sample collection.