SOURCE TERMS, GEOCHEMICAL BEHAVIOR AND CHARACTERIZATION OF URANIUM IN

In nature, U exists primarily in the +IV and +VI oxidation states. In aqueous systems, U(VI) is typically much more soluble than U(IV) due to the formation of various U(VI)-carbonato and U(VI)-hydrolysis species. These U(VI) species can be quite mobile in the environment. However, the adsorption of dissolved U to the solid phase and the microbial reduction of U(VI) to form sparingly soluble U(IV) oxides can limit U mobility in the aqueous environment.

During the last century, there have been several anthropogenic activities that have altered the chemical form, distribution, and mobility of U in the environment. Examples of these activities include the release of depleted uranium projectiles during munitions firing, the concentration of U in soils due to irrigated agricultural activities, and those releases associated with the nuclear fuel cycle.

This presentation will provide a review of U geochemistry followed by a presentation of the anthropogenic (source term) activities that have resulted in the release of U contamination into the environment, the geochemical behavior of U in these contaminated systems and some of the analytical techniques that have been used to characterize the geochemical speciation of U in these systems.