Evaluation of Potential Anthropogenic Pollution of Gd Based on Determination of Rave Earth Elements in Tama-River Water by ICP-MS with Chelate Resin Solid-phase Extraction

Rare earth elements (REEs), except for Sc, Y and Pm in river waters sampled at 15 points from the middle stream area to estuaries in Tama-River, were determined by ICP-MS with solid phase extraction using a chelating resin. The concentration anomalies of Gd, that is, the Gd abundance was higher than adjacent other REE's ones, were steadily seen for all samples from the mixing points with discharging water of a sewage treatment plant at the middle stream to estuaries in REEs patterns, which were drawn by normalizing the concentrations of REEs in each sample with those in PAAS (Post-Archean Australian Average Shale). It is considered that this phenomenon was caused by Gd compounds administered to the human body as contract reagent for MRI. The concentrations of Gd in river water at the middle stream and the estuary area were 2-4 fold and 3-4 fold higher than the literature values reported 20-25 years ago, respectively. Therefore, it is suggested that concentrations of Gd in river water at Tama-River has increased recently. Moreover, the present state of the potential anthropogenic pollution was evaluated in comparison with other river waters by digitalizing the concentration anomalies of Gd as degree of Gd anomaly. As the results, the degree of Gd anomaly at the middle stream in Tama-River were the highest among those reported for domestic river waters so far, and the second highest next to Havel-River in Germany among those for all river waters including foreign river water.