【摘要】 分别用HCl浸取和HF全溶法分析研究沉积物中的同位素2 32 Th、2 30 Th、2 2 8Th ,并对所分析的结果进行全面的对照比较。盐酸浓度、温度及样品的矿物组分都能影响这 3种同位素的酸浸取效率。对于一种确定的沉积物来说 ,在相同的浸取条件下 ,2 2 8Th的酸浸取效率总是高于2 32 Th ,这是由于α辐射子体同位素的反冲作用造成的。与HCl浸取法比较 ,HF全溶法更可靠、更准确。更多还原

【Abstract】 Th、 230 Th and 228 Th in sediments were analyzed with HCl-leaching and HF-total dissolution techniques,and the results are compared. The extraction of these Th isotopes by the leaching treatment,while shown to be influenced by the HCl concentration,leaching temperature,and mineral composition of the sediment,varies for different isotopes. Under the same leaching condition for a given sediment, 228 Th has a higher percentage than 232 Th being solubilized from the sample,due to the recoiled effect imparted to this isotope. 230 Th different from 228 Th has a higher percentage incorporated in the residue from leaching,because the used samples just coming from continent experienced weathering during which a part of U was washed away by natural water from the soluble portion of sample from leaching. The characteristic of 232 Th in leaching is more conservative than 230 Th and 228 Th,its recovery from leaching generally ranges from 60% to 70%,because it is a parent isotope,and an insoluble particle-reactive element. Although more labor-intensive,HF total dissolution should be more reproducing and reliable than the HCl-leaching technique in assessing the Th isotopic composition of a sediment.更多还原