Depth distribution of selected geogenic radionuclides (40K, 226Ra, 232Th) and anthropogenic 137Cs in an undisturbed forest soil in East Slovenia

To reinforce Slovenian radioecological survey information, 20 soil profiles divided into four depth increments of 10 cm were collected in an undisturbed forest in east Slovenia (46 degrees 44'N, 16 degrees 7'E) to establish the natural (K-40, Ra-226 and Th-232) and anthropogenic (Cs-137) level of radioactivity. Using gamma spectrometry and depending on the depth increment, the average activity concentration of radionuclides ranged from 0.5 to 70 Bq kg(-1) for Cs-137, from 535 to 703 Bq kg(-1) for K-40, from 49 to 52 Bq kg(-1) for Ra-226 and from 54 to 62 Bq kg(-1) for Th-232. Based on top soil data (0-10 cm), the radium equivalent activity (Ra-eq) is 167 +/- 7 Bq kg(-1), while absorbed dose rate (D) due to external gamma radiation of 79 +/- 3 nGy h(-1) is higher than the world population-weighted average, reported as 58 nGy h(-1) by UNSCEAR.