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~(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 that emits low-energy (≈0.1 MeV) β-rays (electrons) and generates daughter- (32) P when it decays. ~ (32) P is a commonly used radioisotope, which emits high energy (1.7MeV) β-rays when decayed and has a half-life of 14.3d, which is easy to measure. Therefore, the radioactivity measurement of ~ (32) Si becomes more convenient. ~ (32) Si and ~ (32) P in 2 ~ 3 months to achieve radioactive balance. The radioactivity of ~ (32) P is usually measured by the Cerenkov counting method. The application of ~ (32) Si as a tracer to determine groundwater age range of 50 ~ 1000a, about 200mg Si. The recovery of SiO_2 from natural water with Fe (OH) _3 coprecipitation method can reach 60% ~ 95%, and then ~ (32) P can be extracted. The solution of H_3PO_4 and TritonX-100 were mixed to prepare the counting solution. The radioactivity of ~ (32) P was measured by liquid scintillation counting method. Finally, the radioactive concentration of ~ (32) Si was calculated by the formula.