Radioactive map of soil at Mount Lebanon province and external dose assessment

Abstract

A total of 150 samples were collected from uncultivated areas at 87 locations distributed uniformly along the Mount Lebanon province. Measurements were carried out using gamma spectrometers with high purity germanium detectors. The activity concentrations of primordial radionuclides ranged from 14.0 ± 2.0 to 132.0 ± 8.0 Bq kg−1 for 238U, from 5.4 ± 0.3 to 77.0 ± 3.0 Bq kg−1 for 232Th, from 12.0 ± 1.0 to 227.0 ± 10.0 Bq kg−1 for 226Ra, and from 10.7 ± 0.7 to 714.0 ± 16.0 Bq kg−1 for 40K, with average values of 37, 24, 46, and 206 Bq kg−1, respectively. The average activity concentrations of 238U and 232Th were comparable to the worldwide average value, while that of 40K was found to be half of the world average values stated in UNSCEAR (Sources, effects, and risks of ionizing radiation, United Nations, New York, 2000). The average value of 226Ra was found to be slightly higher than the worldwide value. The activity concentration of the 137Cs at the measurement time in 2015 was found to lie between 0.30 ± 0.06 and 102.00 ± 2.00 Bq kg−1 with an average of 23 Bq kg−1. Surface activity concentrations were calculated, and radioactive maps were plotted. The average value of total absorbed dose rate and the annual effective dose was found to be lower than the world average values. Radium equivalent and external hazard index were within the international recommended values.