| Depleted uranium (DU) has been introduced to the environment in the battlefield and in U.S. Army firing ranges. Soil chemistry differences dictate that DU behaves differently in arid, desert soils than in other soils. Little is published on DU behavior in calcareous soils from arid climates such as the Yuma Proving Ground (YPG), Arizona, where DU-containing penetrators are tested. It is also necessary to understand how remediation efforts may affect DU behavior. The objective of this research was to understand how DU behaves in arid-zone calcareous soils of the southwestern U.S. and how soil amendments used to control phytoremediation affect that behavior. Studies were conducted on soils collected from the YPG and a New Mexico DU-contaminated site to characterize the soil and to (1) observe DU mobility through a 30-cm soil depth as affected by water, manure, and citric acid; (2) characterize DU sorption, and its subsequent desorption with water and citric acid, on soil amended with 0%, 1%, 3%, and 5% compost, and; (3) test different chelating agents on DU, and Pb, to enable remediation efforts by phytoextraction. These studies found that DU leached through the 30-cm soil profile with water and that citric acid treated columns leached a greater amount of DU than the manure amended columns. The mean DU leached from the citric acid columns was 4,152 mg +/- 1,352 and for the manure amended columns the mean was 331 mg +/- 130. Amendment of the soil at three different levels of compost did not alter DU sorption until it reached 5% at which point sorption was reduced. The slope of the 0%, 1% and 3% compost amended isotherms was 12.8 and 4.8 for the 5% isotherm. Water extractable DU was reduced as compost levels increased. Citric acid desorption remained equal for the control (0%) and 1% compost soils, but was lower for the 3% and 5% soils. Of the organic ligands tested, citric acid, DFOB, oxalic acid, malic acid, and succinic acid were best for DU and GLDA, EDTA, NTA, and BayPure RTM for Pb. |
