摘要
光释光(OSL)测年包括等效剂量和环境剂量率的测量,准确测定铀钍钾含量是保证环境剂量率计算准确的重要环节,常用测量方法为电感耦合等离子体质谱与发射光谱法(ICP-MS/OES)联用,但铀钍钾不能同时测定,测量时间长。本文采用ICP-MS和X射线荧光光谱法(XRF)测定光释光沉积物样品中铀钍钾含量并用于环境剂量率的计算。在ICP-MS分析中,对高含量的钾采用电子稀释,减少进入检测器的钾离子,使铀钍钾离子在同一个数量级上,实现了高含量钾和低含量铀钍同时分析,方法检出限铀为6.38ng/L,钍为8.52ng/L,钾为926ng/L。研究了封闭酸溶法和敞口酸溶法对铀钍钾测定的影响,两种溶样方法处理10个沉积物和土壤标准物质,铀钍钾测定结果准确可靠,相对误差无显著差异,均在0~9.33%;但敞口酸溶法操作更简便,样品处理时间(约9h)短于封闭酸溶法(约60h),故ICP-MS分析时选取敞口酸溶法溶解样品。采用压片XRF法测定标准物质中铀钍钾的相对误差分别为4.78%~16.2%、1.20%~13.3%和0.00%~5.67%。ICP-MS和XRF测定20个渤海湾沉积物样品,计算获得环境剂量率的相对偏差在6%以内。XRF更适合测量钾含量高的释光样品;而ICP-MS测定铀钍的检出限更低,精密度和准确度更高,对于超痕量样品,该法测量结果更为准确。
Optically stimulated luminescence(OSL)dating includes the measurement of the equivalent dose and the environmental dose rate.The accurate determination of uranium,thorium and potassium is an important step in ensuring the accurate calculation of the environmental dose rate.The commonly used measurement method is the combination of inductively coupled plasma-mass spectrometry/optical emission spectroscopy(ICP-MS/OES),but the determination of uranium,thorium and potassium can not be done at the same time,and the measurement time is long.In the research,two methods of ICP-MS and X-ray fluorescence spectrometry(XRF)measuring the three elements were compared.Using ICP-MS analysis,electronic dilution was used to reduce the potassium ions entering the detector,so that potassium ions were in the same order of magnitude as uranium and thorium ions.Thus,the simultaneous analysis of high content potassium and low content uranium and thorium was achieved.The detection limits for uranium,thorium,and potassium were 6.38ng/L,8.52ng/L,and 926ng/L,respectively.The effects of closed acid dissolution method and open acid dissolution method on the determination of uranium,thorium,and potassium by ICP-MS method were studied.The two dissolution methods dissolved 10 sediment and soil standard substances,and the results of uranium,thorium,and potassium determination were accurate and reliable,with no significant difference in relative error,ranging from 0 to 9.33%.However,the operation of open acid dissolution method was simpler,and the sample processing time(about 9h)was much shorter than the closed acid dissolution method(about 60h).Therefore,open acid dissolution was selected to dissolve the sample in ICP-MS method.By XRF analysis,the relative errors for the determination of uranium,thorium and potassium in standard materials by pressed-powder pellets method were 4.78%−16.2%,1.20%−13.3%and 0.00%−5.67%,respectively.ICP-MS and XRF were used to determine 20 sediment samples from Bohai Bay,and the relative deviation of the environmental dose rate was less than 6%.XRF has advantages in the measurement of potassium and is more suitable for luminescent samples with high potassium content.The ICP-MS method has a lower detection limit,and higher precision and accuracy for the determination of uranium and thorium.For ultra trace samples,this method provides more accurate measurement results.
作者
王娜
吴磊
王家松
于洋
曾江萍
陈永胜
王福
WANG Na;WU Lei;WANG Jiasong;YU Yang;ZENG Jiangping;CHEN Yongsheng;WANG Fu(Tianjin Center,China Geological Survey(North China Center of Geoscience Innovation),Tianjin 300170,China;Key Laboratory of Coastal Geo-Environment,China Geological Survey,Tianjin 300170,China)
出处
《岩矿测试》
CAS
CSCD
北大核心
2024年第5期793-801,共9页
Rock and Mineral Analysis
基金
中国地质调查局地质调查项目“京津冀协同发展区暨雄安新区资源环境承载能力监测评价”(DD20221727)。
关键词
电感耦合等离子体质谱法
X射线荧光光谱法
环境剂量率
铀
钍
钾
inductively coupled plasma-mass spectrometry
X-ray fluorescence spectrometry
environmental dose rate
uranium
thorium
potassium
作者简介
第一作者:王娜,硕士,高级工程师,主要从事光释光测年及岩石矿物分析研究。E-mail:hmilywna@163.com;通信作者:曾江萍,硕士,高级工程师,主要从事岩石矿物分析研究。E-mail:5058228@qq.com。
