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This article in JEQ

  1. Vol. 27 No. 6, p. 1486-1494
    Received: Jan 5, 1998

    * Corresponding author(s): lvk1@cornell.edu
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The Effect of Acidification and Chelating Agents on the Solubilization of Uranium from Contaminated Soil

  1. Stephen D. Ebbs,
  2. Wendell A. Norvell and
  3. Leon V. Kochian *
  1. U.S. Plant, Soil, and Nutrition Lab., USDA-ARS, Cornell Univ., Ithaca, NY 14853.



The role of acidification and chelating agents in the solubilization of uranium (U) from contaminated soil was examined in a series of experiments. Soil acidification and the addition of chelating agents were the two methods compared initially. The results indicated that the addition of citric acid solubilized more U than acidification or the other amendments tested. This increase in U solubility was, however, transitory. A subsequent experiment indicated that citrate concentration had a more dramatic effect on U solubility than did acidification. The greatest soluble U concentration during this experiment (775 mg kg−1 soil, or ∼85% of the total U) was observed after 24 h in the presence of 20 millimoles citrate kg−1 soil at pH 5. The persistence of U solubility over the 96-h experimental period was primarily a function of pH and citrate degradation. In a separate experiment, in which citric acid rather than citrate was added to contaminated soil, the soluble U concentrations observed were generally lower than those observed in the presence of citrate. Citric acid decreased soil pH to values ≤3.6, and solubilized higher concentrations of Al and Fe than observed in the presence of citrate. Since the maximum solubilization of U was observed at pH 5, the implication of these results is that a combined approach, using both soil acidification and citric acid addition, may be necessary to maximize the phytoextraction of U from soils with a pH > 6.0.

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