^(129)I的海洋放射年代学及其他应用研究进展  

Application process of ^(129)I in marine radiochronology

作　　者：刘广山[1] 纪丽红[1] 

机构地区：[1]厦门大学海洋学系,福建厦门361005

出　　处：《台湾海峡》2010年第1期140-147,共8页Journal of Oceanography In Taiwan Strait

基　　金：国家自然科学基金资助项目(40036010)

摘　　要：应用129I的海洋学研究可分为3个方面:(1)人工129I的年代学,利用人工放射性在沉积物岩心中的记录,包括以核试验全球最大沉降年1963年为参考时间和利用切尔诺贝利核电站事故发生的1986年作为参考时间的年代测定.(2)利用宇生129I的年代学,测年体系主要有地热流体、天然气水合物和石油地质体系.(3)利用核燃料后处理厂排放的129I进行的海洋环流与混合研究.核试验和核事故释放的129I测定的是现代沉积物年代,测年时间尺度为50a.人们提出人类利用原子能之前地球表层初始129I丰度为1.5×10-12,并以该值作为利用宇生129I估算年代的初始丰度值.半衰期和丰度探测下限水平允许宇生129I可测年的时间尺度为80Ma.本文综述了以上几方面的研究进展.海洋多金属结核和结壳的生长速率为毫米每兆年量级,一块1～10cm大小的多金属结核和结壳所能涵盖的时间尺度约为10～100Ma,刚好是129I测年的时间尺度,所以本文提出了多金属结核和结壳可能是合适的129I测年介质的观点.Application of 129I in oceanography include： （1） dating by 129I released from nuclear test and accident recorded in sediment core, in which peaks related with maximum atmospheric deposition of anthropogenic radioactivity released during nuclear test was in 1963 and Chernobyl Nuclear Power plant accident happened in 1986; （2） dating using cosmogenic 129I, the dating system are at present geothermal fluid, gas hydrate and oil information; （3） marine circulation and mixing traced by 129I discharged from nuclear fuel reproeessing plants. The modem sediment was dated by anthropogenic 129I in the time scale of 50a. Without anthropogenic radioactivity, the initial 1291 abundance of surface reservoir of earth is confirmed as 1.5 × 10 -12 that can be used as starting value for calculation of cosmogenic 1291 dating. The half-life and detection limit of abundance allows cosmogenic lzgI dating within range of 80Ma. This paper summarize above developments of 129I dating. The growth rate of Polymetallic nodule and crust is about mm/Ma, and time scales of a piece of 1 - 10cm the size of the polymetallic nodules and crusts can cover about 10 - lOOMa, so we thought that the polymetallic nodule and crust may be the best mediums for 129I dating.

关 键 词：海洋化学 129I 年代学 人工放射性核素 宇生放射性核素 综述 

分 类 号：P734.24[天文地球—海洋化学]