The specific activities of natural radionuclides ((40)K, (226)Ra and (232)Th) and Chernobyl-derived (137)Cs were measured in soil profiles representing typical soil types of Belgrade (Serbia): chernozems, fluvisols, humic gleysols, eutric cambisols, vertisols and gleyic fluvisols. The influence of soil properties and content of stable elements on radionuclide distribution down the soil profiles (at 5 cm intervals up to 50 cm depth) was analysed. Correlation analysis identified associations of (40)K, (226)Ra and (137)Cs with fine-grained soil fractions. Significant positive correlations were found between (137)Cs specific activity and both organic matter content and cation exchange capacity. Saturated hydraulic conductivity and specific electrical conductivity were also positively correlated with the specific activity of (137)Cs. The strong positive correlations between (226)Ra and (232)Th specific activities and Fe and Mn indicate an association with oxides of these elements in soil. The correlations observed between (40)K and Cr, Ni, Pb and Zn and also between (137)Cs and Cd, Cr, Pb and Zn could be attributed to their common affinity for clay minerals. These results provide insight into the main factors that affect radionuclide migration in the soil, which contributes to knowledge about radionuclide behaviour in the environment and factors governing their mobility within terrestrial ecosystems.

No abstract

This study evaluates the influence of the largest Serbian coal-fired power plant on radionuclide concentrations in soil profiles up to 50 cm in depth. Thirty soil profiles were sampled from the plant surroundings (up to 10 km distance) and analyzed using standard methods for soil physicochemical properties and gamma ray spectrometry for specific activities of natural radionuclides (40K, 226Ra and 232Th). Spatial and vertical distribution of radionuclides was determined and analyzed to show the relations between the specific activities in the soil and soil properties and the most influential factors of natural radionuclide variability were identified. The radiological indices for surface soil were calculated and radiological risk assessment was performed. The measured specific activities were similar to values of background levels for Serbia. The sampling depth did not show any significant influence on specific activities of natural radionuclides. The strongest predictor of specific activities of the investigated radionuclides was soil granulometry. All parameters of radiological risk assessment were below the recommended values and adopted limits. It appears that the coal-fired power plant does not have a significant impact on the spatial and vertical distribution of natural radionuclides in the area of interest, but technologically enhanced natural radioactivity as a consequence of the plant operations was identified within the first 1.5 km from the power plant. [Projekat Ministarstva nauke Republike Srbije br. III43009 i br. III41005]

Background: Terrestrial radiation emitted from naturally occurring radionuclides, such as 40K and radionuclides from the 238U and 232Th series and their decay products represent the main external source of irradiation to the human body. The purpose of this study was to provide a preliminary assessment of the doses from terrestrial exposure of population in Serbia and to estimate a potential radiation hazard for population inhabiting investigated areas. Methods: The gamma dose rates, external hazard indexes, and annual effective doses due to terrestrial naturally occurring radionuclides (238U, 232Th and 40K) were calculated based on their activities in soil samples in Serbia as determined by gamma-ray spectrometry. Results: The total absorbed gamma dose rate due to these radionuclides varied from 16.9 to 125 nGy h-1, with a mean of 62.8 nGy h-1. Assuming a 20% occupancy factor, the corresponding annual effective dose varied from 2.07 to 15.4×10-5 Sv with the mean value of 7.7×10-5 Sv, i.e. annual effective dose was in range of the world wide average values. Conclusion: According to the values of external hazard index obtained in this study (mean Hex = 0.35), the radiation hazard was insignificant for the population living in investigated areas

Among radionuclides in the soil deposited after Chernobyl accident, 137Cs poses considerable environmental and radiological problems because of its relatively long half-life (30.17 y), its abundance in the fallout, high mobility and similarity to potassium as the major plant nutrient. In this study the samples of undisturbed surface soil (n=250) were taken from 70 regions in Belgrade, during 2006-2010. The specific activities of 137Cs were measured by gamma-ray spectrometry. Based on obtained results external effective dose rates were calculated according to the internationally accepted activity to dose rate conversion equations. The specific activities of 137Cs were geographically mapped. The presence of 137Cs has been detected in all soil samples, with high variability of its specific activity, ranging from 3 Bq kg-1 to 87 Bq kg-1. The mean specific activity of 137Cs was 23 Bq kg-1 and the corresponding absorbed dose was 1.5 nSv h-1. The observed range reflects the inhomogeneity of the deposition process following the Chernobyl accident. It could also be attributed to topographic differences and spatial differences in physicochemical and biological soil properties, soil type and vegetation cover. The results of the present study could be valuable database for future estimations of the impact of radioactive pollution.