A Study of the Accumulation Factor of the Daughter Products of Radon Decay in the Surface Layer Using Beta Spectrometry

Abstract

This research is devoted to studying the distribution and factor of accumulation of the beta activity of natural radionuclides in the soil surface layer in Almaty (Republic of Kazakhstan). Soil samples were collected during the period from April to May 2018 in different parts of the city of Almaty. A map of distribution of beta activity in Almaty was constructed on the basis of the results of measurements of beta spectra of soil samples. Soil was sampled according to the following procedure: the collected soil was dried overnight and crushed and its residual moisture and beta spectrum were then measured. The average exposure time of measurements was 90 min per spectrum. In addition to background beta particles generated by cosmic rays, the intensity of the beta spectrum is influenced by the existence of temporal variations in radon emanation and the radon activity in air can vary over the period of a day in a relatively wide range. As a result, the concentration of radon decay daughter products (RDDPs) on aerosols of air will affect the background of beta particles. Therefore, the background spectrum of beta particles was measured after measuring each soil sample. Therefore, RDDP radionuclides are generated in the surface layer of the atmosphere and in atmospheric precipitation on the basis of aerosol particles. In turn, radon atoms emanating from the lower soil layers coagulate with aerosol particles. The factor of accumulation of beta radionuclides of RDDPs depends on the chemical composition of the soil cover, as well as on meteorological conditions and the chemical properties of beta radionuclides themselves, which determine their ability to migrate and accumulate in the surface soil layer. The obtained integral values of beta radionuclides of RDDPs show a spatial fractal spread and correspond to the published data taking into account precipitation during the sampling period.