Transfer Factors from Soil to Plant of Natural Radionuclides at Abu-Ghraib City, Iraq Using Gamma Ray Spectroscopy

Abstract

Activity concentrations of natural radionuclides, artificial radio-cesium, and soil-to-plant transfer factor in common different plants species grown at Abu-Ghraib city in the capital Baghdad have been evaluated using NaI(Tl) gamma spectroscopy. Five species of plants have been selected, namely green pepper, cucumber, celery, basil, and mint. The measurements were made on four parts of each plant sample which were included soil, roots, stalk, and leave for knowledge and evaluation the transfer factors. The maximum mean specific activity concentration of U-238 and Th-232 was 9.853±10.904 Bq/kg, 6.005±2.729Bq/kg in celery, while the maximum mean specific activity concentration of K-40 was 141.172±71.703 Bg/kg in cucumber, respectively. The results showed that the uranium, thorium, potassium and cesium concentration not exceeded the permissible limit. The mean Radium equivalent activity was 35.553 Bq\\kg lower than 370 Bq\\kg recommended by UNSCEAR. The maximum absorbed dose rate in root-mint samples was 30.290 nGy/h which is lower than 84 nGy/h, while the mean annual outdoor effective dose equivalent in root samples was 148.597 mSv/y which is lower than 290 mSv/y recommended by UNSCEAR, respectively. The maximum H hazard index was 0.097 in root samples which is less than ≤1 recommended by UNSCEAR. The excess lifetime cancer risk (ECLR) ranged from 5.441×10 −3 to 520.081×10 −3. This value is higher than recommended limit 0.29 ×10 −3 and 1.16 ×10 −3 reported by UNSCEAR. The ELCR is a function of environmental geology and K-40 has very high soil-to-plant transfer factor compared to other radionuclides in the samples. Therefore, there is a risk of their administration. The maximum of radioactivity level index was 0.265 Bq/kg which is less than ≤1.