Geochemical Research Sheds Light on Plutonium Mobility in the Environment
There is a concern that the mobility of plutonium (Pu) in the environment at some DOE legacy waste sites may be increased due to the formation of complexes with the metal-complexing compound ethylenediaminetetraacetic acid (EDTA), which was co-disposed with Pu. At issue is whether EDTA enhances the solubility and therefore the mobility of Pu(IV). Researchers at Pacific Northwest National Laboratory examined the mobility of Pu(IV)-EDTA complexes under common environmental conditions and found that they are not as mobile as previously assumed. The complexation of Pu(IV) with EDTA is affected by competitive complexation reactions with other common inorganic species such as Fe, Al, Ca and Mg. EDTA also readily adsorbs to geologic materials and is biodegraded by microorganisms commonly found in the environment. These other competitive reactions ultimately reduce the potential for EDTA to complex and mobilize Pu in the environment suggesting that Pu(IV)-EDTA complexes are not responsible for the observed mobility of Pu in the environment.
Journal of Solution Chemistry 37 957-986, 2008.