Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad, Pakistan.
J Hazard Mater. 2011 Aug 15;192(1):78-85. doi: 10.1016/j.jhazmat.2011.04.102. Epub 2011 May 4.
The NORM (naturally occurring radioactive material) in phosphate rock is transferred as TENORM (technologically enhanced naturally occurring radioactive material) to phosphatic fertilizers and to the waste generated by the chemical processes. The waste generated at the NP (nitrophosphate) fertilizer plant at Multan in Pakistan is PCC (precipitated calcium carbonate). Thirty samples of the PCC were collected from the heaps of the waste near the fertilizer plant. Activity concentrations of radionuclides in the waste samples were measured by using the technique of gamma ray spectrometry consisting of coaxial type HPGe (high purity germanium) detector coupled with a PC (personal computer) based MCA (multichannel analyzer) through a spectroscopy amplifier. Activity concentrations of (226)Ra, (232)Th and (40)K in the waste samples were determined to be 273 ± 23 (173-398), 32 ± 4 (26-39) and 56 ± 5 (46-66) Bq kg(-1) respectively. The activity concentration of (226)Ra in the PCC waste was found to be higher than that in naturally occurring calcium carbonate (limestone and marble) and in worldwide soil. Radiological hazard was estimated from indoor and outdoor exposure to gamma rays from the PCC. Indoor annual effective dose was higher than 1 mSv. Potential radiological pollution in the environment from TENORM in the PCC has also been addressed.
磷矿中的天然放射性核素（NORM）在磷酸肥料和化学过程产生的废物中以技术增强的天然放射性核素（TENORM）的形式转移。巴基斯坦木尔坦硝酸磷肥厂产生的废物是沉淀碳酸钙（PCC）。从肥料厂附近的废物堆中收集了 30 个 PCC 样品。使用伽马射线能谱法，通过同轴型高纯锗（HPGe）探测器与基于 PC 的 MCA（多道分析器）相连，通过光谱放大器，测量了废物样品中放射性核素的活度浓度。测定了废物样品中（226）Ra、（232）Th 和（40）K 的活度浓度分别为 273 ± 23（173-398）、32 ± 4（26-39）和 56 ± 5（46-66）Bq·kg（-1）。PCC 废物中的（226）Ra 活度浓度高于天然碳酸钙（石灰岩和大理石）和世界范围内土壤中的活度浓度。通过室内和室外暴露于 PCC 伽马射线，评估了放射性危害。室内年有效剂量高于 1 mSv。还讨论了 PCC 中 TENORM 对环境造成的潜在放射性污染。
