Environmental natural radioactivity in the lower atmosphere

Abstract

The method of aerosol filtration has been used for the collection of natural radioactivity, fission products and stable nuclei present in the lower atmosphere. Alpha spectroscopy, beta counting and X-ray spectrometry have been used for activity measurements. Computer techniques which enable the individual concentrations of 222Rn and 220Rn daughters to be accurately determined are described. Under stable atmospheric conditions, the RaA (218Po) concentration at ground level reaches 1 pci/L while at a height of 17.3m it is found to be 0.28 pci/L. For average turbulent conditions, this concentration may be reduced by a factor of 10. The activities of 222Rn and 220Rn at ground level are estimated to have a ratio of 1:40, while at a height of 17.3m this ratio is 1:400. Diurnal variations of radioactivity at this altitude are correlated with some meteoroligical parameters. Stable nuclei such as copper, iron, lead and bromine are also found to be collected on the filter in trace amounts.