四酸消解-低本底计数法测定土壤中210Po和210Pb的比活度  

Determination of specific activity of 210Po and 210Pb in soil by four-acid digestion-low background counting method

作　　者：时燕华 刘娟 吴小鹿 臧旭芳 刘念 周润泽 SHI Yanhua;LIU Juan;WU Xiaolu;ZANG Xufang;LIU Nian;ZHOU Runze(Experimental Testing Team of Jiangxi Geological Bureau,Nanchang 330002,China)

机构地区：[1]江西省地质局实验测试大队,江西南昌330002

出　　处：《冶金分析》2025年第1期38-45,共8页Metallurgical Analysis

基　　金：江西省地质局核与能源类项目(2023HYN08);2024年度科技计划项目(2024JXDZKJRC08)。

摘　　要：同位素210Po(钋-210)和210Pb(铅-210)均是具有强烈放射性和毒性的核素,它们对人体健康和环境构成严重威胁。采用α能谱法测定210Po、β射线法测定210Pb,存在前处理复杂、效率较低,不能同时测量的问题。实验选择硝酸-盐酸-氢氟酸-高氯酸四酸体系,实现土壤样品一次性高效快速消解,大幅度缩短了制样时间。对样品提取的酸度、温度、时间等关键参数进行优化,得到最佳制源条件:抗坏血酸+盐酸羟胺混合体系作掩蔽剂,在0.5 mol/L盐酸-3.5 mol/L氯化钠体系溶液下处理样品,设定振荡速度为140 r/min,振幅为20 mm,制源温度为90℃,制源时间为80 min。制备的铜箔样品源在8 h后通过低本底计数法测定。利用210Pb的子体210Bi及二级子体210Po的衰变规律,通过贝特曼原子核多级衰变方程修正非平衡状态时的活度,确定方法检出限210Po为0.011 Bq,210Pb为0.010 Bq。根据碱熔法和四酸法进行制源,选取标准物质SGP140203-3进行探测效率实验,选择标准物质GBW04127进行回收率和精密度试验。其中使用碱熔法时,210Po、210Pb的探测效率分别为24.4%、35.6%,回收率为81%~94%、85%~100%,相对标准偏差(RSD,n=10)为6.0%、6.1%;使用四酸法时,210Po、210Pb探测效率分别为27.7%、38.1%,回收率为95%~107%、98%~110%,RSD(n=10)为4.6%、4.7%。结果表明四酸法测定结果更接近于理论值,回收率稳定且满足EJ/T 751—2014的要求(90%~110%)。Isotopes 210Po (polonium-210) and 210Pb (lead-210) are highly radioactive and toxic nuclides,which have serious threats to human health and the environment.Traditional methods for the determination of these isotopes,such as α spectrometry for 210Po and β spectrometry for 210Pb,have some problems such as complex pretreatment and low efficiency.Moreover,the simultaneous determination of both isotopes cannot be performed.In this study,a "four-acid" system(nitric acid-hydrochloric acid-hydrofluoric acid-perchloric acid) was employed to efficiently and rapidly digest the samples in one step,significantly reducing the sample preparation time.The key parameters such as the acidity,temperature and time for sample extraction were investigated to obtain the optimal conditions:the mixture of ascorbic acid and hydroxylamine hydrochloride was used as the masking agent;the sample was treated in the system containing 0.5 mol/L hydrochloric acid and 3.5 mol/L sodium chloride;the oscillation speed was set at 140 r/min with amplitude of 20 mm;the sample preparation temperature was 90 ℃,and the preparation time was 80 min.The copper foil sample sources prepared were measured using a low-background counting method after 8 h.Based on the decay patterns of progeny 210Bi and subsequent progeny 210Po of 210Pb,the activities in non-equilibrium states were corrected by applying the Bateman equation for multi-level radioactive decay.The limits of detection were 0.011 Bq for 210Po and 0.010 Bq for 210Pb.The samples were prepared by alkali fusion method and four-acid method.The certified reference material SGP140203-3 was selected for the detection efficiency test,and the certified reference material GBW04127 was used for the recovery and presion test.When the alkali fusion method was used,the detection efficiencies for 210Po and 210Pb were 24.4% and 35.6%;the recoveries were 81%-94% and 85%-100%;the relative standard deviations (RSD,n=10) were 6.0% and 6.1%,respectively.When the four-acid method was used,the detection efficiencies for 2

关 键 词：四酸消解 低本底计数法 土壤 210Po 210Pb 210Bi 贝特曼方程 比活度 

分 类 号：X837[环境科学与工程—环境工程]