Esan Deborah T, Ajiboye Yinka, Obed Rachel I, Ojo Joshua, Adeola Mary, Sridhar Mynepalli K
Afe Babalola University, Ado-Ekiti, Nigeria.
University of Ibadan Faculty of Science, Ibadan, Nigeria.
Environ Health Insights. 2022 May 23;16:11786302221100041. doi: 10.1177/11786302221100041. eCollection 2022.
The distribution of natural radioactivity levels of U, Th, and K in soils overlying the 3 lithologic units within Obafemi Awolowo University, Ile-Ife, Nigeria was investigated to characterize the gamma radiation dose distribution over the lithologies and to assess the radiation hazard due to the natural radionuclides. A thallium-doped cesium iodide detector was employed to determine the activity concentrations of U, Th, and K in 21 soil samples. The respective average concentrations of the 3 radionuclides are 37.7, 3.2, and 245.6 Bq kg for granite gneiss, 31.9, 2.8, and 241.1 Bq kg for banded gneiss, and 21.1, 1.7, and 196.7 Bq kg for mica schist. The average concentration of U in granite gneiss lithology exceeds the world average value. The evaluated values of radiation hazard parameters including average absorbed dose rate, outdoor annual effective dose and external hazard index are below the recommended limits. The spatial distribution of the radiation hazard parameters evaluated over the lithologies has been delineated. The highest average cancer risk of 1.15 per 10 000 population was obtained for the study area within the soil overlying the banded gneiss lithology. Generally, the radiation hazard from the soils in study area poses no significant health hazard.
对尼日利亚伊费奥巴费米·阿沃洛沃大学内3个岩性单元之上土壤中铀、钍和钾的天然放射性水平分布进行了调查，以表征岩性上的伽马辐射剂量分布，并评估天然放射性核素造成的辐射危害。采用掺铊碘化铯探测器测定了21个土壤样品中铀、钍和钾的活度浓度。花岗岩片麻岩中这3种放射性核素的各自平均浓度分别为37.7、3.2和245.6 Bq/kg，条带状片麻岩为31.9、2.8和241.1 Bq/kg，云母片岩为21.1、1.7和196.7 Bq/kg。花岗岩片麻岩岩性中铀的平均浓度超过世界平均值。包括平均吸收剂量率、室外年有效剂量和外照射危害指数在内的辐射危害参数评估值均低于推荐限值。已描绘出在各岩性上评估的辐射危害参数的空间分布。在条带状片麻岩岩性之上土壤内的研究区域，每10 000人口的最高平均癌症风险为1.15。总体而言，研究区域土壤的辐射危害不会造成重大健康危害。
