Radionuclide species comprising the primordial radioactive decay chains lead by ²³²Th and ²³⁸U, along with their associated daughter and granddaughter decay series, constitute a major fraction of the naturally occurring radioactive material (NORM). Gamma-ray radiation emitted by the decay of these NORMs, along with the ⁴⁰K in the soil, is mainly responsible for the human exposure to external gamma-rays. The radioactivity concentrations in soil samples collected from 138 sites have been determined as part of a survey to produce a radiological map of AL-Qassim, Al-Ghat, Al-Majmaah, and Al-Zulfi regions in the Kingdom of Saudi Arabia. The estimated mean values of ²³⁸U, ²³²Th, ⁴⁰K, ²²⁶Ra, and gross α and β activities in the samples were 23.8 ± 11.61, 24.33 ± 17.63, 790 ± 398, 22.83 ± 11.70, 375 ± 205, and 734 ± 344 Bq kg⁻¹, respectively. The radiological risk indices related to the natural radioactivity in the soil samples, i.e., the absorbed dose rate in air, radium equivalent activity, and annual effective dose rate, were estimated to be 58.88 ± 29.21 nGy h⁻¹, 117.1 ± 59.65 Bq kg⁻¹, and 0.07 ± 0.04 mSv year⁻¹, respectively. The determined internal hazard index of the samples ranged from 0.07 to 1.45, with an estimated mean value of 0.4 ± 0.2. The radon concentration in the soil gas ranged from 39 to 508 Bq m⁻³, with a mean value of 145.0 ± 52.9 Bq m⁻³.

中文翻译：

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在Al-Qassim，Al-Ghat，Al-Zulfi和Al-Majmaah的土壤中建立自然放射性基准，绘图和放射性危害评估

包含由²³² Th和²³⁸ U引导的原始放射性衰变链的放射性核素及其相关的子代和孙女衰变系列构成了天然放射性物质（NORM）的主要部分。这些NORM的衰变所发射的伽马射线辐射以及土壤中的⁴⁰ K，是人类暴露于外部伽马射线的主要原因。作为调查的一部分，已经确定了从138个站点收集的土壤样品中的放射性浓度，以绘制出沙特阿拉伯王国的Q-Qassim，Al-Ghat，Al-Majmaah和Al-Zulfi地区的放射线图。估计的平均值²³⁸ U，²³² Th，⁴⁰ K，样品中的²²⁶ Ra和总α和β活性分别为23.8±11.61、24.33±17.63、790±398、22.83±11.70、375±205和734±344Bq kg ^-1。土壤样品，即，在相关的天然放射性的放射线风险指数，在空气中，镭同等活性，和年有效剂量率的吸收剂量率，估计为58.88±29.21 NGYħ ^-1，117.1±59.65贝公斤^-1和0.07±0.04 mSv年^-1。确定的样品内部危险指数范围为0.07至1.45，估计平均值为0.4±0.2。土壤气体中的concentration浓度范围为39至508 Bq m ^-3，平均值为145.0±52.9 Bq m ^-3。