Level of radionuclide (90Sr) in Niigata Prefecture, 4

In order to grasp concentration level of artificial radionuclides in index plants in Niigata Prefecture, Artemisia princeps Pamp. (mugwort) was sampled from 16 places in the prefecture, and investigation was made on the level of 90Sr, following that of 137Cs in the last year. At portion of the leaf, the level of 90Sr was in the range of 0.64 to 20 Bq/kgwet (Mean: 3.6 Bq/kgwet). In addition, the ratio of 90Sr at portions of the leaf and the stem was in the range of 1:1 to 2:1, being the same as that of stable Sr. The ratio of Ca was between 2:1 and 4:1, and 90Sr per unit Ca showed the tendency to be smaller at the leaf portion than at the stem portion. In comparison of 90Sr and 137Cs in mugwort, 90Sr was denser, but 90Sr/137Cs was heavily dependent on the place where sampled and showed no correlation between the both. However, the ratio of 90Sr/137Cs at portions of the leaf and the stem went in the range between 1:1 and 1:2. (author)