抄録
Radiochemical measurements of 239, 240Pu were carried out for a total of 288 individual rain and snow samples collected at Fayetteville (36°N, 94°W), Arkansas, during the period between February 1976 and October 1984. The results indicate that the plutonium inventory in the northern stratosphere has been decreasing during the past several years at a rate corresponding to about 1.2 years for the mean stratospheric residence time of plutonium. However, the fallout of plutonium may not be attributable solely to the atmospheric injections of nuclear debris from the weapons tests. It appears that the recent volcanic eruptions may have played an important role in altering the stratospheric inventory of plutonium.
