Investigations on radioactive equilibrium in the lower atmosphere between radon and its short-lived decay products

Abstract

The variations in the degree of equilibrium between radon and its short-lived decay products have been studied at 2 meters above the ground surface at a selected location near Trombay, Bombay, India. The correlations between the degree of equilibrium and different meteorological parameters such as atmospheric stability, wind speed and direction, atmospheric pressure, temperature, relative humidity and rainfall, have been studied. Diurnal and seasonal variations in the concentration of radon and in the degree of equilibrium have also been studied. The degree of equilibrium has been found to range from 4 to 100 % depending on meteorological conditions. This has been studied by making simultaneous measurements of actual radon decay product activity in a sample of air and the equilibrium decay product activity in the same air. The degree of equilibrium has been defined as the percentage of equilibrium daughter product activity actually present in a sample of air. The equilibrium daughter product activity has been measured by filtering out the daughter products from a known volume of air and subsequently allowing the daughter products to grow to equilibrium concentration in the presence of aerosols in a reservoir. The application of these investigations in understanding the mixing processes in the lower atmosphere have been discussed.