Uptake of munitions-derived depleted uranium by three grass species

Uptake of depleted uranium (DU, 238U) derived from weathered munitions was assessed in a greenhouse experiment utilizing three common grass species, Schizachyrium scoparium (little bluestem), Buchloe dactyloides (buffalograss), and Aristida purpurea (purple threeawn). Both aboveground and belowground uptake was dependent on the soil DU concentration, and on the experimental moisture regime utilized during the experimental duration. Uptake was enhanced under higher moisture regimes, suggesting a greater degree of DU solubility and concomitant plant availability. Concentration ratios (calculated by dividing plant tissue DU concentrations by soil DU concentrations) decreased with increasing soil DU concentrations, but increased as more moisture was applied. The toxicity level of DU in root tissue was estimated to 270mg kg^-1.