MEASUREMENT OF URANIUM COMPLEXATION BY DISSOLVED ORGANIC MATTER USING HYPHENATED TECHNIQUES

Reactive transport models (RTMs) for uranium in groundwater need to incorporate chemical speciation. Two important aqueous ligands for uranium are dissolved organic matter and carbonate ion. The sorptive characteristics, and thus the potential for groundwater transport, of these species are likely to be different. The separation techniques of size exclusion chromatography (SEC) and field-flow fractionation (FFF), when interfaced to ICP-MS can be used to determine uranium speciation. These techniques have the benefits of high-resolution size separations and small sample size requirements (microliters). To validate the techniques, results of the SEC-ICP-MS and FFF-ICP-MS measurements were compared to model predictions made using Visual MINTEQ. Potential applications to monitoring in-situ recovery (ISR) operations will be discussed.