Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/1998
Publication Date: N/A
Technical Abstract: Selection of plant species and amendments for the phytoremediation of uranium (U) contaminated soil has been hampered by a lack of information regarding the form and mechanism by which plants accumulate U. U uptake by plants was characterized using a hydroponic system that provided U as single predominant species in solution, rather than a complex mixture of species. The results indicated that at pH 5.0, the uranyl cation (UO22+) was more readily taken up and translocated by pea seedlings (Pisum sativum) than the hydroxyl or carbonate U complexes present in solution at pH 6.0 and 8.0, respectively. The results of these experiments suggested that the soil amendment used for U phytoremediation should be one capable of solubilizing and complexing the uranyl cation. A soil incubation experiment, which compared the solubilization of U by organic acids (oxalic, citric) and synthetic chelates (HEDTA), indicated that citric acid dwas 100 times more effective in solubilizing U than oxalic acid or HEDTA. This result was not surprising, given the high affinity of citric acid (a tricarboxylic acid) for the uranyl cation. A subsequent pot study in which U-contaminated soil was amended with citric acid indicated that the addition of citric acid dramatically increased U accumulation by beet (Beta vulgaris). In addition to providing fundamental information regarding the form of U taken up by plants, this study has also demonstrated the importance of fundamental research to the field of phytoremediation. Funding for this research was provided by a grant from the U.S. Department of Energy, Division of Energy Biosciences to Leon Kochian (Interagency Agreement DE-A102-95ER21097).