| 摘要: |
| 建立了适合海水U、Th同位素高精密度测量要求的MC-CP-MS方法.确定了采用Mg(OH)₂共沉淀法富集海水U、Th同位素时的最佳NH₃·H₂O浓度为0.14 mol/dm³.采用CRM-45U标准溶液，经质量分馏、电子倍增器增益、丰度灵敏度、仪器及试剂本底和记忆效应等校正后，历时3个月得U/²°U和"U/U的准确度分别优于0.05%和0.08%,精密度分别优于0.12%和0.10%.将该方法应用于台湾海峡B9站位3份平行水样中U、Th同位素含量及比值的测定，得U平均含量为3.05±0.05μg/kg,"U/U平均值为(6.28±0.11)×10-⁵,U含量及其同位素比值的标准偏差均小于3%;Th的平均含量为(1.66±0.04)×10³pg/kg,"Th/Th平均值为(1.95±0.01)×10⁹,Th含量及其同位素比值的标准偏差均小于2%.测定结果与海区的水文学条件及物质来源相吻合，证明了方法的可靠性。 |
| 关键词: 海洋化学 海水 铀 钍 MCHCP-MS |
| DOI： |
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| 基金项目:国家自然科学基金资助项目(41276063):中国大洋协会国际海域资源调查与开发“十二五”资助项目(DY12543R-06) |
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| Long-lived U and Th high precision measurementmethod of MC4CP-MS in seawater |
| LU Yanna,CAI Yihua,XING Na |
| (College of the Environment and Eoology,Xiamen University,Xiamen 361102,China;College of Ocean and Earth Science,Xiamen University,Xiamen 361102,China) |
| Abstract: |
| A high precision method has been developed for analyzing uranium and thorium in seawater by MCHCP-MS in this study.The optimal raio of NH₃·H₂O with acidified seawater of pH=2(0.14 mol/dm³)is quantifiedfor Mg(OH)₂coprecipitation protocol.The instrument and solvent background,abundance sensitivity,memoryeffects,mass fractionation and IC gains are properly corrected using CRM-45U standard.Overal,the accuracy ofu/"U andU/U are better than 0.05%and 0.08%with precisions beter than 0.12%and0.10%,respec-tively,in about 3 month measurements of CRM145 Ustandard.This method has been successfully applied to ana-lyze triplicate suface seawater samples from the Taiwan Strait.The average concentrations ofU and²Th are 3.05±0.05μg/kg and(1.66±0.04)×10³pg/kg,respetively,while the average ratios of²"u/²U and2Th/2°Th are(6.28±0.11)×10-⁵and(1.95±0.01)×10⁹,respectively.The standard deviations are lessthan 3%for Uisotopes and 2%for Th isotopes.The results are consistent with hydrological characteristics and iso-topic provenance in the study area,which support the reliability of the method. |
| Key words: marinechemistry seawater uranium thorium MC4CP-MS |
