Deposition of excess amount of natural U from the atmosphere

The concentration of 238U in rain and snow collected at Fayetteville (36 degrees N, 94 degrees W), AR, showed a marked increase during the summer months of 1980; and also during spring 1981, while Mount St. Helens remained active. This observed increase of 238U was due to the fallout of natural U from the eruption of Mount St. Helens. Based on the results from the analysis of rain and snow samples for the period March 1980-October 1982, the amount of 238U brought down by the rain is estimated to be 6.55 X 10(3) Ci.