Lithogenic radionuclides in surface soils of Serbia: Spatial distribution and relation to geological formations

• The radionuclide concentrations varied among different geological formations.
• Their mutual relationships were analyzed to reveal relative depletion or enrichment.
• Geostatistical analysis indicated areas of highest radionuclide concentrations.
• The highest concentrations were found in granitoid and volcanic complexes of Serbia.

The survey results of concentrations of lithogenic radionuclides in surface soils from 213 locations in Serbia, their mutual concentration ratios and spatial distribution are presented. The mean concentrations of uranium, thorium and potassium in soils of 2.6 mg kg− 1, 9.3 mg kg− 1 and 1.8·104 mg kg− 1, respectively, were found to be similar with equivalent values reported for soils of regions with similar geological composition and geotectonic structures and also with worldwide average values. The spatial distribution of analyzed radionuclides was geostatistically interpolated using ordinary kriging. The spatial distribution maps of uranium, thorium and potassium concentrations showed their variability among different regions as a consequence of different lithological units of the investigated area.