Solution Species of Plutonium in the Environment

Abstract

Abstract Information regarding the oxidation states of Pu in environmental samples is needed for estimating its migration through the geologic media. Predictions based upon thermodynamic data indicate that in the Eh ‐pH range of natural aqueous environments, the dominant species of Pu is likely to be Pu[V] in relatively oxidizing environments and Pu[III] in reducing environments. Because of the lack of methods of determining Pu[V] in environmental samples containing trace concentrations of Pu, Pu[V] has not been previously identified in these samples. Plutonium[VI] has generally been assumed to be the dominant species in relatively oxidizing environments. However, the results presented in this paper show that solutions in equilibrium with 239 Pu[IV] hydroxide contain Pu[V]. The presence of Pu[V] in solutions contacting 239 PuO 2 (s) is also inferred from the data.