多接收电感耦合等离子体质谱法Pb含量对Cu同位素比值测定的影响

The employment of either doping or standard-sample-bracketing method for mass fractionation during isotope ratio measurement using multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) assumes that the instrumental fractionation is the same for both standards and samples. The effect of Pb in Cu solutions on Cu isotope measurement using MC-ICPMS is reported.     

北京市大气颗粒物分级样品的铅同位素丰度比测量与来源研究

报道了北京市2004年夏、冬季分级采样样品的化学组成和铅同位素丰度比数据,并对铅来源进行了分析。采用电感耦合等离子体原子发射光谱（ICP-AES）和电感耦合等离子体质谱（ICP-MS）技术分析了24个无机元素浓度,同时用多接收器电感耦合等离子体质谱（MC-ICP MS）技术测定铅同位素丰度比。结果表明：细颗粒（PM2.5）中的铅含量明显高于粗颗粒（PM10~2.5）,可吸入颗粒物（PM10）中80%以上的铅存在细颗粒。细颗粒的206Pb/207Pb比值处于1.140~1.156的范围;粗颗粒的206Pb/207Pb比值处于1.127~1.148的范围,总体上低于细颗粒。北京市大气铅来源复杂、多样,有2个或3个以上,主要来源除了燃煤排放还有涉铅有色冶金排放。基于前期工作积累的较多样品测量数据,燃煤排放的206Pb/207Pb代表性比值为1.163 3;涉铅有色冶金排放源的数据较少,初步判断处于1.11~1.15之间,中值为1.13。夏季、冬季细颗粒中燃煤源贡献率分别为0.51和0.59;涉铅有色冶金源的贡献率分别为0.49和0.41。北京市大气铅污染同时具有当地排放和区域性排放的贡献和特征。     

激光-多接收等离子体质谱测定石笋的Mg/Ca比

A method for determining Mg/Ca of stalagmite by LA-MC-ICPMS is studied. 24Mg/44Ca (Mass 22, intensity of 44Ca2 , collected by ion counting and mass 24, intensity of 24Mg , collected by Faraday cup) ratios were measured in replace of Mg/Ca ratios. Both diameter of laser sampling spot and laser moving increment were 20 μm. The curve of Mg/Ca vs. distance directly was obtained. The result indicates that relative Mg/Ca ratios changed from 0.5 to 2.0 in this stalagmite and it is enough to reflect environmental factors act.     

多接收电感耦合等离子体质谱法测定Nd同位素标准物质

The precision and accuracy of Nd isotope analysis using multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) is verified through repeated measurements of standard reference materials of JMC Nd2O3 and GBW04419. A mixed solution of Nd separated from hundreds of geological samples is measured for 143Nd/144Nd ratio, which produces excellent long-term repeatability. This solution, named as CAGS-Nd-1, can be used as an in-house reference material for monitoring instrument stability during Nd isotope measurements.     

岩浆过程中铁同位素的地球化学行为

铁同位素在岩浆过程中可以发生明显的分馏。相对于地幔橄榄岩(δ⁵⁶Fe平均值约为0‰),玄武岩略微富集铁的重同位素(δ⁵⁶Fe平均值约为0.1‰)。相对于中基性岩浆岩,酸性岩浆岩更加富集铁的重同位素。岩浆过程中的铁同位素分馏主要受铁的价态或氧逸度所控制。通常岩浆岩中的三价铁矿物(如磁铁矿等)相对于二价铁矿物(如橄榄石、辉石等)富集铁的重同位素。地幔橄榄岩部分熔融过程中,由于Fe³⁺比Fe²⁺更加不相容,熔体比固体相更加富集Fe³⁺,因而部分熔融产物(通常为玄武岩)相对富集铁的重同位素。在结晶分异过程及低氧逸度条件下,橄榄石、辉石等含Fe²⁺的矿物结晶导致熔体更加富集Fe³⁺,熔体铁同位素组成变重;在高氧逸度条件下,磁铁矿等含Fe³⁺的矿物结晶促使熔体更加富集Fe²⁺,熔体铁同位素组成变轻。在流体出溶过程中,出溶的流体相对富集铁的轻同位素,残余的岩浆铁同位素组成变重。现有研究表明,铁同位素在示踪岩浆作用方面具有很大潜力。