摘要
^(32)Si是放射性同位素,它衰变时发射低能量(≈0.1MeV)的β—射线(电子)并生成子体^(32)P。^(32)P是一个常用的放射性同位素,衰变时发射高能量(1.7MeV)的β—射线,半衰期为14.3d,容易测量,因此使^(32)Si的放射性测量变得较为方便。^(32)Si和^(32)P在2～3个月内可达到放射性平衡。^(32)P的放射性通常用切伦科夫计数法测量。应用^(32)Si作为示踪剂测定地下水年龄范围为50～1000a,大约需要200mg Si。用Fe(OH)_3共沉淀法从天然水中提取SiO_2回收率可达60%～95%,然后提取^(32)P。将H_3PO_4溶液和TritonX-100混合制备计数溶液,用液体闪烁计数法测量^(32)P的放射性,最后用公式计算^(32)Si的放射性浓度。
^(32)Si is a radioisotope. It emits β-radiation (electrons) of low energy (≈0.1MeV) and yields a daughter ^(32)P. The measurement of ^(32)Si radioactivity is therefore greatly facilitated by the presence of ^(32)P,a currently employed radioisotope which can be easily measured due to the high energy of emitted β-radiation (1.7MeV) and its favourable half-life (14.3 days). The ^(32)Si and ^(32)P radioactive equilibrium is reached in 2-3 months. The ^(32)P radioactivity is usually measured by Cerenkov's counting method. The time scales which can be conveniently studied using ^(32)Si as a tracer lain in the range of 50-1000 years. This method needs 200 mg Si. The overall yield for extraction of silicon using Fe(OH)_3 coprecipitation from natural waters varies between 60—95 per cent. Then ^(32)P is extracted. The counting solution is prepared by H_3O_4 solution and TritonX-100. The radioactivity measurement of ^(32)P is proceeded by liquid scintillation counting method and the ^(32)Si radioactivity is finally calculated by the equation.
出处
《地质科技情报》
CAS
CSCD
北大核心
1996年第2期83-88,共6页
Geological Science and Technology Information
基金
国家自然科学基金资助项目(49472160)成果
