Plant Uptake and Behavior of Depleted Uranium in Arid Zone Soils.
April L. Ulery1, Ramona R. Parra1, Victoria Anne2, and Yohei Hashimoto3. (1) New Mexico State Univ, Dept of Agronomy & Horticulture, P.O. Box 30003, MSC 3Q, Las Cruces, NM 88003, (2) U.S. Forest Service, Region 10, P.O. Box 493, Petersburg, AK 99833, (3) Dept of Soil Science, North Carolina State Univ, Box 7619, Raleigh, NC 27695
Soil may become contaminated from the use and testing of Depleted Uranium (DU) ammunition in war zones and military firing ranges. Many of these contaminated sites are in arid and semi-arid regions. Phytoremediation is an in-situ method of soil decontamination that may be more cost-effective and cause less disturbance to soil than excavation and other non in-situ methods. Phytoremediation of DU from soil is dependent on the use of plants that effectively extract and accumulate uranium. We have conducted several experiments in the lab, the greenhouse, and the field to screen for potential phytoextractors that could accumulate uranium from soil in arid and semi-arid regions. This poster will present some of the challenges and rewards involved with phytoremediation in arid zones. Of over fifty species tested in a variety of experiments, none would be considered hyperaccumulators according to accepted definitions, although coyote gourd (Cucurbita palmate) and wild candytuft (Thlaspi alpestre) were both able to extract over 150 mg U per kg soil without any of the chelates commonly used to make the metal bioavailable. Application of citrate ion, either as citric acid or ammonium citrate increased uranium translocation from contaminated soil to the shoots of kochia (Kochia scoparia) and amaranth pigweed (Amaranthus retroflexus) grown in the greenhouse. Steer manure application to DU contaminated soil at several rates either decreased or had no effect on the amount of uranium extracted by plants. Results from sand culture and various amended-soil pot studies will be presented and discussed.