Rhenium contents in Japanese river waters measured by isotope dilution ICP-MS and the relationship of Re with some chemical components

Rhenium (Re) concentrations in 450 samples collected from 45 Japanese rivers were determined using inductively coupled plasma mass spectrometry (ICP-MS) to understand Re behavior in the geological environments. The isotope dilution method (ID), which included chemical separation and concentration steps, was applied to obtain Re recovery. Using the ID method we concentrated Re in the water 20 times. Direct sample injection was also carried out to compare the results with ID; agreement was good, but ID had lower relative standard deviations with almost 100% Re recovery from the water. The geometric mean was 0.81 ng/L. When the Re concentrations in the uppermost sampling point of each river and 60 other chemical properties in the waters were compared, good correlations were observed with 12 elements and ions; the highest correlation was observed with SO₄^2- (R=0.72). The results implied that the possible chemical form Re in parent rocks was sulfides. (author)