Geospatial and Statistical Analysis of Natural Radionuclides in the Soil of Kirkuk Province, Iraq

The concentration levels of ²²⁶Ra, ²³²Th, and ⁴⁰K were investigated in the soil samples of the study area using a γ-ray spectroscopy system based on a high-purity germanium detector. The study determined that the average levels of ²²⁶Ra, ²³²Th, and ⁴⁰K ranged from 7.2 ± 0.4 to 34.2 ± 3.8 Bq kg⁻¹, 4.7 ± 0.2 to 30.2 ± 4.1, and 104 ± 31 to 442 ± 53 Bq kg^- 1, with average values of 23.5 ± 2.5, 17.6 ± 2.1, and 264 ± 33 Bq kg^- 1, respectively. The average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K indicate a slight decrease compared to the worldwide average. The radiological risk factors corresponded to average values of 32.48 nGy h^- 1, 62.08 nGy h^- 1, 0.34 mSv y^- 1, 0.14 × 10^- 3, 146.22 µR h^- 1, and 228.98 µSv y^- 1 for the external and internal absorbed dose, total annual effective dose equivalent, ELCR, exposure rate, and annual gonadal equivalent dose, correspondingly. The average values of the measured hazards indices were 67.11 Bq kg^- 1, 0.19, 0.25, 0.51, and 0.12 for the radium equivalent activity, external and internal indices, representative level, and alpha indices, respectively. Several of these results are greater than the worldwide average, but the average of these values remains within the internationally permissible range. The statistical analysis of our results involved the computation of various measures in order to analyze and verify the statistical correlations.