GEOC 23 |
| Scott W. Frazier, Institute of Terrestrial Ecology, Swiss Federal Institute of Technology Zurich, Soil Chemistry, Grabenstrasse 3, Schlieren, CH-8952, Switzerland, Ruben Kretzschmar, Institute of Terrestrial Ecology, Swiss Federal Institute of Technology, Zurich, Grabenstrasse 3, CH-8952 Schlieren, Switzerland, and Stephan Kraemer, Institute of Terrestrial Ecology, ETH Zuerich, Grabenstrasse 3, Schlieren, CH-8952, Switzerland. |
| Many remediation strategies for actinide polluted soils attempt to immobilize actinides through precipitation. The precipitated phases are considered to be highly immobile based on thermodynamic predictions of solubility. However, organic ligands such as siderophores could mobilize precipitated actinides by increasing the solubility and the dissolution kinetics of precipitated actinides. Though siderophores are designed to dissolve iron(III), tetravalent actinides share many characteristics with iron(III) suggesting that the actinides might be amenable to siderophore promoted dissolution. We have chosen a microbial siderophore (Desferrioxamine B or DFO-B) as a model siderophore to study uranium(IV)dioxide dissolution. We used batch and steady-state dissolution experiments to demonstrate that DFO-B was extremely effective at both dissolving and increasing the solubility of our uranium oxide. Surface-saturated dissolution rates for our uranium oxide were 60 nmol/hr m2 compared to 0.6 nmol/hr m2 for goethite. These results suggest that organic ligands could largely affect the mobility of precipitated actinides in the environment. |
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Chemistry of Metals in Terrestrial and Aquatic Systems
8:10 AM-11:30 AM, Monday, March 29, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |