Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad, Pakistan.
Centre of Excellence in Marine Biology, University of Karachi, Pakistan.
Radiat Prot Dosimetry. 2020 Jul 13;189(2):234-241. doi: 10.1093/rpd/ncaa035.
Chemical phase and distribution of natural radionuclides (226Ra, 232Th and 40K) were determined for sand samples collected from ten different beaches of Karachi. All samples, except one, were identified with major and minor phases as SiO2 and CaCO3, respectively. The average activity concentrations were 24.9, 25.0 and 239 Bq kg-1 for 226Ra, 232Th and 40K, respectively. Including all samples, the average radium equivalent activity was 79.1 Bq kg-1. The external and internal radiation hazard indices and representative level index were all found below unity. The average air absorbed dose rate at 1 m above the sand due to the natural radionuclides was 18.3 nGy h-1, which was less than the world average for soil. The corresponding annual effective dose rate was 22.4 μSv y-1. It was found that Raeq had positive significant correlation with the amount of quartz present at the beaches.
对从卡拉奇的十个不同海滩采集的沙样进行了天然放射性核素（226Ra、232Th 和 40K）的物相和分布研究。除了一个样本之外，所有样本均被鉴定为主要相和次要相，分别为 SiO2 和 CaCO3。226Ra、232Th 和 40K 的平均活度浓度分别为 24.9、25.0 和 239 Bq kg-1。包括所有样本在内，镭当量活度平均为 79.1 Bq kg-1。外部和内部辐射危害指数以及代表性水平指数均低于 1。由于天然放射性核素，在距沙面 1 米高处的空气吸收剂量率为 18.3 nGy h-1，低于世界土壤的平均水平。相应的年有效剂量率为 22.4 μSv y-1。研究发现，Raeq 与海滩上存在的石英量呈正显著相关。
