Sources, Speciation and Mobility of Plutonium and other Transuranics in the Groundwater at the Savannah River Site

This annual report summarizes work to date on our EMSP project: Sources, Speciation and Mobility of Plutonium and Other Transuranics in the Groundwater at the Savannah River Site? (Sept. 2003-Sept. 2006 SIGNIFICANCE TO DOE EMSP Migration of plutonium in the environment is a major issue at several DOE sites (Riley and Zachara, 1992)). As such, fundamental data concerning the interactions between various chemical forms of plutonium with compounds in the environment are essential for predicting Pu's behavior in the aqueous environment. Our research has focused on two important DOE sites, namely the Savannah River Site and the Hanford Site, and at both sites we see no need to invoke colloid facilitated transport to explain Pu groundwater distributions. This conclusion has important practical implications because much of the uncertainty associated with Pu subsurface transport, including at the Hanford Site (Mann et al. 1998) and the SRS (McDowell et al., 2000) is attributed directly to the uncertainty associated with the role that mobile colloids may or may not play in transporting Pu