【摘要】 <正> 一、前言在用²¹⁰Pb法测定湖泊或近海的现代沉积速率时,由²²⁶Ra的放射性强度来计算补偿的²¹⁰Pb可获得更准确的沉积速率;此外,²²⁶Ra是极毒的长寿命亲骨性核素,对人体危害极大,故被列为环境监测的主要对象。鉴于上述原因,建立一种快速、灵敏、可靠的测定沉积物中²²⁶Ra的分析方法,具有重要意义。测定²²⁶Ra的方法主要有α放射法,射气法,和γ谱法等。由于沉积物中²²⁶Ra的含量很低,一般在10^-12居里/克以下。因此在分析过程中,必须对沉积物中的²²⁶Ra进行分离和富集,同时选择一种既灵敏又准确的分析方法。本文提出了用阴离子交换分离,EDTA再纯化,硫酸钡镭制源,最后进行α计数的测定²²⁶Ra的方法。用该方法测定了厦门港海区三个站位沉积岩心中不同层次的²²⁶Ra含量,为该海区的环境评价提供了必要的数据。更多还原

【Abstract】 A method for marine sediment ²²⁶Ra analys’s by anion-exchange separation, EDTA purification and（RaBa）SO₄ source has been developed. It has a sensitivity of 3.0×10^-14Ci/g（dried weight）for 5 g of sediment samples. The decontamination factors for some importer alpha radionuclei, such as U, Th and Po, approached 10³ or greater. The chemical recovery of Ba was 73.5±3.6% and the radiochemidal recovery of ²²⁶Ra was 65.7±5.7%.The method has been applied to the determination of ²²⁶Ra in marine sediment samples from the Xiamen Harbour. The ²²⁶Ra content in cores from three stations was about 1.0 dpm/g （dried weight）,更多还原