Migration behavior of Eu(III) in sandy soil in the presence of dissolved organic materials

Migration behavior of Eu(III) in sandy soil in the presence of dissolved organic material (DOM) was studied by the column experiments using a constant feed technique. A site specific DOM, isolated from the groundwater at Chalk River in Canada, a reagent humic acid (HA) from Aldrich Co. Ltd. and Suwannee River HA and River fulvic acid (FA) from the International Humic Substances Society, as reference materials, were used in this study for comparing their effects on the mobility of Eu(III). Solutions of 152Eu in the presence of the DOMs at pH 5.5 and ionic strength of 0.01 M NaClO4 were introduced onto the column (2.5 cm I.D. x 2.5 cm long) packed with the sandy soil at a constant flow rate of 1.0 mL . min-1. In the absence of DOM, Eu was not detected even after 90 pore volumes were eluted from the column. Europium elution was observed, however, when any of the DOMs were present. Maximum relative concentrations of Eu were observed in the order: River FA < Groundwater DOM < River HA = Aldrich HA. This sequence suggests that differences in characteristics of DOM may be reflected in mobility of Eu-DOM complexes in sandy soil. (orig.)