Pu同位素比值在沉积物测年中的应用  

Pu isotope ratios as the geochronometer for sediments

作　　者：杨旭[1] 潘少明[1] 徐仪红[1] 阮向东[2] 管永精[2] 

机构地区：[1]南京大学地理与海洋科学学院,江苏南京210093 [2]广西大学物理科学与工程技术学院,广西南宁530004

出　　处：《海洋通报》2013年第2期227-234,共8页Marine Science Bulletin

基　　金：国家自然科学基金项目(41166002;41271289)

摘　　要：环境中137Cs的衰变使得137Cs时标法在沉积物定年研究中的应用受到越来越大的局限。与137Cs来源相同的Pu同位素,在定年上具有更多的优势。且由于核材料在制作工艺和设计上的差异,不同来源的Pu具有不同的Pu同位素比值,所以根据其比值的差异也可以推演沉积年代。在分析放射性核素Pu的来源、定年的基本原理及其优势的基础上,综述了239+240Pu及Pu同位素比值在沉积物定年中的应用,在海洋、河口、湖泊等不同的沉积环境中,239+240Pu在沉积物中分布的特征值与137Cs一样可以作为时标定年,同时Pu同位素比值也可为沉积物计年提供特异的时标。且将239+240Pu的时标与Pu同位素比值定年所得的沉积年代信息相结合,可使得到的沉积年代信息更可靠,提高定年的精度。The use of 137Cs as a geochronometer for the sediments dating will be more and more difficult. The plutonium isotope, with the same source as that of 137Cs, has a number of advantages in the sedment datings. Due to different production processes and designs, the Pu isotope ratios will vary among Pu with different sources. The depositional age can be deduced based on the variance. The paper summarized the function of 239Pu and Pu isotope ratios in sediment dating by analyzing radionuelides Pu from three aspects： （1） the sources of Pu; （2） the basic princ!ples of the Pu isotope dating; （3） the advantages of Pu isotope dating. The results showed that in different sedimentary environments such as the ocean, estuaries or lakes, the eigenvalue of 239＋240pu which distributed in sediments, as 137Cs, could serve as the time scale in isotopic dating. The Pu isotope ratios could also provide some specific time scales for dating sediments. Moreover, the information of the depositional age will be more reliable if we combine the 239＋240Pu time scales with the depositional age suggested by Pu isotope ratios, and the accuracy of isotopic dating will be enhanced as well.

关 键 词：240Pu/239Pu 239+240Pu 238Pu/239+240Pu 沉积物计年 

分 类 号：P512.2[天文地球—地质学]