用Fe(OH) 3共沉淀从天然水中提取纯化SiO2 ,回收率在 30 %～ 98% ,然后提取32 P ,将H3PO4溶液和PicoflourLLT混合制备计数溶液 ,用液体闪烁计数法测量32 P的放射性 ,计算32 Si的放射性浓度 ,最后确定地下水的年龄。通过对河北平原浅层地下水的32 Si年龄进行测定 ,所得的32 Si年龄为 92 9 89a± 1 7 87a,与1 4 C的校正年龄一致 The coprecipitation of Fe (OH) 3 was used to extract and purify SiO2 from natural water. The recoveries were between 30% and 98%. 32P was then extracted. The counting solution was prepared by mixing H3PO4 solution and Picoflour LLT. The radioactivity of 32P was measured by liquid scintillation counting. Calculate the radioactive concentration of 32 Si, and finally determine the age of groundwater. By measuring the 32 Si age of shallow groundwater in the Hebei Plain, the 32 Si age obtained was 92 9 89a ± 1 7 87a, consistent with the corrected age of 14 C