Interactions and Transport of Plutonium-Humic Acid Particles in Groundwater Environments

Abstract

ABSTRACTPu adsorption on pure γ-alumina and heterogeneous mineral phases was investigated as a function of pH and humic acid (HA) concentration. Information on surface speciation was obtained by using various actinides as valence analogues for Pu. Surface redox transformations of Pu(V) appeared to control Pu uptake onto electron exchanging minerals. A one-dimensional transport experiment of high molecular weight HA in water saturated clayey sand column was performed under reducing conditions (Eh <-200 mV). This showed that HA particles larger than 600 nm were retained in the column. The HA breakthrough curve was characterized by extended tailing. Physico-chemical interactions at the mineral surface and particle straining in smaller pore spaces appeared to control HA transport through the soil. The chemical association of Pu with moving HA was investigated by leaching of 238-Pu-doped borosilicate glasses. Enhancement in Pu release rate was observed in HA solutions compared with organic-free groundwater.