Evaluation of elemental concentrations of uranium, thorium and potassium in top soils from Kuwait

Top soil samples across the state of Kuwait numering ninety were collected and analysed using gamma-ray spectrometry, to evaluate the elemental concentration of U-238, Th-232 and K-40 and their depletion/ enrichment. Results of elemental concentration ranges from 0.48 to 2.61 mg/kg, 0.87-5.23 mg/kg, and 0.24-2.23%, with a mean values of 1.39 mg/kg, 3.47 mg/kg, and 1.18%, for the U-238, Th-232 and K-40, respectively. Further analysis was conducted amongst the five identified soil types, i.e. Aquisalids (S1), Calcigypsids (S2), Petrocalcids (S3), Petrogypsids (S4), and torripsamment (S5). The highest radioactivity concentrations from both uranium and thorium were recorded in the S2 (Calcigypsids) soil, with a value of 1.71 (mg/kg) and 4.45 (mg/kg), respectively. Minimum and maximum values of K-40 are 1.1(%) and 1.27(%) and is prevalent in Aquisalids (S1) and Petrocalcids (S3) soil types, respectively. Ratios of elemental Th-232/U-238, K-40/U-238, concentration for K-40/Th-232 across the soil types are 2.53, 0.09 and 0.03, with a correlation coefficient of 0.92, 0.34, and 0.38, respectively. A progressively higher Th-232/U-238 ratio is observed moving south-wards, indicating lower U-238 content in soils from the south relative to the northern part. Overall results indicate Kuwait to be relatively an area with low level of natural radioactivity. (C) 2019 Korean Nuclear Society, Published by Elsevier Korea LLC.