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 238U, 232Th and 40K 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 238U, 232Th and 40K, 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 40K are 1.1(%) and 1.27(%) and is prevalent in Aquisalids (S1) and Petrocalcids (S3) soil types, respectively. Ratios of elemental concentration for 232Th/238U, 40K/238U, 40K/232Th 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 232Th/238U ratio is observed moving south-wards, indicating lower 238U 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. Keywords: Gamma-ray spectrometry, NORM, Radioactivity concentration, Elemental concentration, Concentration ratio, Depletion/ enrichment