河北山前平原地下水^(32)Si年龄初探

32 Si dating of piedmont plain groundwater in Hebei

３２Ｓｉ是放射性同位素，半衰期约１４０ａ，可以测定５０～１０００ａ地下水的年龄。本文用Ｆｅ（ＯＨ）３共沉淀法从天然水中提取ＳｉＯ２，回收率可达３０％～９８％。然后提取和纯化３２Ｐ，将Ｈ３ＰＯ４溶液和Ｐｉｃｏ－ｆｌｏｕｒＴＭＬＬＴ混合制备计数溶液，用液体闪烁计数法测量３２Ｐ的放射性，本底计数为４．８０ｃｐｈ，仪器效率为４５．３４％，然后用公式计算样品的３２Ｓｉ放射性浓度和地下水的３２Ｓｉ年龄。

Si is a radioisotope with a half life about 140 years.It can be used as a tracer for the datiing of groundwater in the range of 50～1000 years.In this paper,the total yield of extraction of silica using Fe(OH) 3 coprecipitation from natural water varies between 30～98 percent.Then 32 P is extracted and parified.The counting solution is prepared by mixing H 3PO 4 solution and Pico flour TM LLT.The radioactivity measurement of 32 P is proceeded by liquid scintillation counting method with the background of 4 80 cph and the efficiency of 45 34%.The 32 Si radioactivity of the sample and 32 Si ages of groundwater are finally calculated by the equation.