Distribution of Natural and Anthropogenic Radionuclides in Soil Samples in Recreational Zones of Moscow

Recreational zones play an important role in human life in urban environment. The activities of natural radionuclides and Cs-137 were determined by low background gamma-ray spectrometry in soil samples collected at two depths (0-5 and 5-20 cm) in 15 recreational zones of Moscow. The average activity concentrations of analyzed radionuclides were 519, 35.1, 29, 1.9, and 8.0 Bq/kg for (40) K, Th-232, U-238, U-235, u and Cs-137, respectively. The distribution of natural radionuclides and Cs-137 in soil profiles showed almost uniform distribution of natural radionuclides and decrease of Cs-137 with the increase of the depth. A number of radiological indices, namely radium equivalent activity, external and internal risk assessment, gamma-index, annual effective dose, and excess lifetime cancer risk, were calculated to assess the level of radiological hazard for population. The values of calculated parameters are within the recommended safety limits, showing that soil in studied recreational zones does not pose a serious threat to human health.