Abstract
Content of plutonium in the water of eight main rivers in Japan was determined. The average value of the total content of plutonium is 1.4x10-3pCi/l in which 0.4x 10-3 pCi/1 is contained in the suspended matter. The annual run-off plutonium is only 0.12% of the accumulated plutonium on land. This suggests that the fallout plutonium is adsorbed on soil surface firmly and it is difficult to be leached out.
