Abstract

Uptake of natural radionuclides by vegetables cultivated on contaminated soil may contribute significantly to the radiation exposure of a population. This study evaluated the activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in 27 soil and 27 irrigation water samples from different farms in Lagos using Hyper Pure Germanium (HPGe) detector. Activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K from soil samples were used to estimate some radiological hazard indices. The mean values of the activity concentrations for ²²⁶Ra, ²³²Th, and ⁴⁰K in irrigation water were 2.29 ± 0.28, 0.38 ± 0.03, and 2.17 ± 0.51 Bq/l, respectively. The values for ²³²Th and ²²⁶Ra were 62% lower and 129% higher than their respective reference values while the value for ⁴⁰K was within the values reported by similar studies. The mean specific activity for ²²⁶Ra, ²³²Th, and ⁴⁰K in soil samples were 10.99 ± 3.75, 11.20 ± 5.36, and 19.38 ± 15.81 Bq/kg. These were 70, 75, and 81% lower than their respective world’s average values. The values of the hazard indices, radium equivalent, representative level index (RLI), mean absorbed dose, outdoor annual effective dose, internal hazard index, external hazard index, and excess lifetime cancer risks (ELCRs) were 28.50 Bq/kg, 0.20, 12.50 nGy/h, 15.35 μSv/yr, 0.11, 0.08, and 0.05 × 10⁻³, respectively. These values were 92, 80, 72.27, 78.07, 89, 92, and 82.76% below their respective world’s average values and safe limits. The soils in the study area do not present any potential radiological effects. The use of surface water for irrigation, however, poses radiological risks to consumers of vegetables. Irrigation water is, therefore, a potential source of elevated concentrations of ²²⁶Ra in vegetables cultivated in Lagos metropolis.

摘要

在受污染土壤上种植的蔬菜对天然放射性核素的吸收可能会显着增加人群的辐射暴露。本研究使用超纯锗 (HPGe) 检测器评估了拉各斯不同农场的 27 个土壤和 27 个灌溉水样品中²²⁶ Ra、²³² Th 和⁴⁰ K的活度浓度。^{土壤样品中226} Ra、²³² Th 和⁴⁰ K 的活度浓度被用来估计一些放射性危害指数。²²⁶ Ra、²³² Th 和⁴⁰的活度浓度平均值灌溉水中的 K 分别为 2.29 ± 0.28、0.38 ± 0.03 和 2.17 ± 0.51 Bq/l。²³² Th 和²²⁶ Ra 的值比它们各自的参考值低 62% 和高 129%，而⁴⁰ K 的值在类似研究报告的值范围内。²²⁶ Ra、²³² Th 和⁴⁰的平均比活度土壤样品中的 K 分别为 10.99 ± 3.75、11.20 ± 5.36 和 19.38 ± 15.81 Bq/kg。这些分别比各自的世界平均值低 70%、75% 和 81%。危害指数、镭当量、代表水平指数（RLI）、平均吸收剂量、室外年有效剂量、内部危害指数、外部危害指数和超额寿命癌症风险（ELCRs）的值为28.50 Bq/kg，0.20， 12.50 nGy/h、15.35 μSv/yr、0.11、0.08 和 0.05 × 10 ^-3， 分别。这些值分别比其各自的世界平均值和安全限值低 92、80、72.27、78.07、89、92 和 82.76%。研究区的土壤不存在任何潜在的放射性影响。然而，使用地表水灌溉会给蔬菜消费者带来辐射风险。因此，灌溉水是拉各斯大都市种植的蔬菜中^{226 Ra 浓度升高的潜在来源。}