SPATIAL VARIABILITY OF 137Cs IN THE SOIL OF BELGRADE REGION (SERBIA)

Among radionuclides in the soil deposited after Chernobyl accident, Cs-137 poses considerable environmental and radiological problemdue to its relatively long half-life (30.17 gamma), 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 Cs-137 were measured by gamma-ray spectrometry. Based on obtained results, the external effective dose rates were calculated according to the internationally accepted activity to dose rate conversion equations. The specific activities of Cs-137 were geographically mapped. The presence of Cs-137 has been detected in all soil samples, with high variability of its specific activity, ranging from 3 to 87 Bq kg(-1).The mean specific activity of Cs-137 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.