核试验^(14)C在法医学上的应用:确定不明死者的出生时间

The application of bomb ^(14)C in forensic:Determination of date of birth for unknown victims

伴随着20世纪50年代及60年代初大规模的大气层核试验活动,原本稳定的大气中CO2的14C含量迅速升高,并通过生物地球化学循环渗透到整个生物圈,自1963年《部分禁止核试验条约》签订后,大气中CO2的14C含量开始迅速减少,其速度却远超过了14C自身的衰变速度,树轮和珊瑚等环境信息载体的14C记录都体现了这一迅速增长而后又衰减的过程。近50年对全球大气中CO2的14C含量的数据采集和发布,使人们发现了14C含量作为现代时间标尺的可行性。介绍了现代核试验14C在法医学鉴定中新的应用方向——根据牙釉质的14C含量确定不明身份死者的出生年代。对于无法判定样品形成于大气14C含量峰值前后的问题,尝试应用同一个人釉质完成时间不同的两颗牙齿的14C含量比较,来予以解决。实验数据结果与真实记录之间的绝对误差为1.4a,优于以前骨龄和牙齿磨损度等传统的法医鉴定方法。

The ^14C content in the atmosphere increased dramatically during the artificial nuclear test activities in the 1950s and early 1960s, which broke the stable condition of ^14C in the atmosphere. Consequently, the excessive ^14C in the atmosphere transferred into biosphere through biogeochemical cycle. As a result of the Test Ban Treaty in 1963, atmospheric ^14C declines, with a speed much faster than the ^14C radioactive decay. This process was recorded in many kinds of environment indexes, such as tree rings, corals, etc. With more and more records of ^14C content in the atmosphere all over the world in the last 50 yrs, ^14C became a new practical modern timepiece. The application of nuclear ^14C in forensic investigation is introduced in this study. The date of birth of unknown victim can be determined by the analysis of the ^14C content in their enamel. The evolution of the bomb atmospheric ^14C implies that one ^14C content corresponds to two time results, i.e., before and after the bomb peak. This problem can be feasibly solved by comparing two teeth of different enamel formation time from the same person. The average absolute difference in this study is 1.4 yrs, which is much better than the traditional forensic investigation method, such as skeletal age, dental morphology and so on.