Study of atmospheric washout processes by means of radon decay products

Abstract

A measurement of the departure from radioactive equilibrium between Po/ sup 218/, Pb/sup 214/, and Bi/sup 214/ in a rain cloud or i n fresh rain water can provide an insight into the washout process occurring in the cloud. A convenient and easy method for estimating this departure was developed. The method consists in measuring the rate of change of the resultant activity of Bi/ sup 214/ in the rain sample as a function of time without separating the parent nuclides Po/sup 218/ and Pb/sup 214/. Several rain samples collected at Bombay were analyzed using this method. The results give upper limits for the rate of removal of activity from an air mass by condensation processes on the basis of the simplified continuous washout model discussed.