利用铅同位素比值判断丹参不同产地来源

建立了用微柱流动注射与电感耦合等离子体质谱联用的铅同位素比值测量方法。利用铅与5-磺基-8-羟基喹啉的螯合反应在线分离测定丹参样品中的铅同位素比值，并利用铅同位素比值的分布进行中药丹参产地来源的研究。实验结果表明，相同地区来源的丹参样品其铅同位素比值分布相对集中，而不同地区来源的丹参，铅的同位素比值则有明显的区别。因此，铅的同位素比值可作为中药材的产地来源判别依据。     

土壤及其他背景样品中铅同位素比值的测定方法

为给铅同位素示踪技术在判别土壤、大气、水体和人体中铅与相关重金属污染来源,区别汽车尾气铅污染和工业铅污染等方面的应用提供科学依据。通过大量的对比条件实验,拟出了土壤、煤、汽车尾气和气溶胶样品中铅同位素比值的测定方法。利用这三个流程分别测定了采自杭州茶园的土壤及茶园附近的煤、汽车尾气和气溶胶样品的铅同位素比值,其中207Pb/206Pb的精度(2σ)均优于±0.03%。重复样误差优于±0.05%2。08Pb强度一般均在1V以上,有的高达8 V以上。监控分析流程的国际标准物质NBS981的207Pb/206Pb为0.91449±0.00004。全流程本底铅为10-8数量级。     

电感耦合等离子体质谱法测定水泥样品中的铅同位素比值

研究和讨论了用电感耦合等离子体质谱仪(ICP—MS)测定铅的同位素比值测定时，影响测试结果的准确度和精密度的主要因素及其优化过程。在优化后的仪器分析条件下，测定5μg/L的NIST SRM981自然丰度铅同位素标准溶液的各对铅同位素比值，获得的^207Pb／^206Pb分析精度可优于0．1％。在该条件下测定了14个不同的水泥粉样品中的铅同位素比值，结果显示：铅的同位素比值分析技术可以用来示踪环境监测样品的铅污染源。     

汽油中痕量铅的电感耦合等离子体质谱法同位素比值分析

为建立汽油中痕量铅的等离子体质谱的同位素比值分析方法,考察使用了不同的样品处理手段处理汽油样品。结果表明,V(HNO3) V(H2O)=1 10体系萃取汽油,为汽油中同位素比值分析的最佳方法,其操作安全简单,方便快速,且灵敏度高,从而有效保证同位素比值分析的精确度。利用等离子体质谱仪对汽油中痕量铅的实际含量进行了分析,为配合城市大气铅污染来源调查工作提供了一种极为快速简捷、安全有效的手段。     

西北旱田黄土中铅的赋存形态与转化规律研究

采用Tessier连续提取法分析不同条件下旱田黄土中Pb的形态分布与转化规律,通过正交试验确定影响Pb形态转化的主要因素,借助Mul1er地积累指数法初步评价污染状况。结果发现:所用黄土样品中Pb总量为68.85mg·kg-1,低于国家标准《土壤环境质量标准》二级标准。不同形态Pb含量分布为残渣态Fe-Mn氧化态有机结合态碳酸盐结合态可交换态,其中残渣态Pb占Pb总量的64.04%。土壤pH值、含水率、秸秆加入量、老化时间等环境因素能改变Pb的形态分布,但残渣态Pb含量始终最高。pH值是影响土壤Pb赋存形态的最主要因素,Pb的地积累指数Igeo为0.3314,说明采样区土壤人为污染比较严重。     

应用多接收器电感耦合等离子体质谱法测定海洋碳酸盐中稳定铅同位素组成

研究了多接收器电感耦合等离子体质谱仪(MC-ICP MS)测定铅同位素比值时,影响测试结果准确度和精密度的主要因素及其优化过程。在优化条件下,10 h内连续30次测定4 ng/mL NIST SRM 981同位素标准溶液铅同位素比值,获得208Pb/206Pb、207Pb/206Pb和206Pb/204Pb相对标准偏差(RSDs)分别为0.005%、0.004%和0.054%。长期监测208Pb/206Pb、207Pb/206Pb和206Pb/204Pb,标准偏差(2SDs)分别为0.000 06、0.000 05和0.006 7。采用NEPTUNE MC-ICP MS法测定了低铅海洋碳酸盐样品中稳定铅的同位素比值,并对南海橙黄滨珊瑚(Porites lutea)和库氏砗磲(Tridacna gigas)进行了分析,得到全流程空白为8～10 pg,重复样误差优于0.1%。经0.50 mol/L HNO3洗脱之后,得到海南珊瑚样品中208Pb/206Pb、207Pb/206Pb的比值分别为2.086 2±0.001 5、0.849 90±0.001 47(n=16);海南砗磲样品中208Pb/206Pb、207Pb/206Pb的比值分别为2.116 9±0.004 2、0.864 81±0.001 62(n=9)。进一步考察了南海海洋碳酸盐中204Pb的同位素比值。分析结果表明,南海海洋碳酸盐中稳定铅同位素比值与中国气溶胶、珠江三角洲大气沉降、黄土及南海海底玄武岩等具有很好的相关性。方法适用于复杂基体高钙低铅的海洋碳酸盐样品中铅同位素比值的分析。     

锶稳定同位素比质谱在进口大麦原产地溯源中的应用研究

利用热电离质谱检测了进口自加拿大、法国、澳大利亚和美国的大麦样本的⁸⁷Sr/⁸⁶Sr同位素比值。研究了TIMS测定进口大麦⁸⁷Sr/⁸⁶Sr同位素比值的精密度，利用SPSS 25.0对不同进口国大麦样本的⁸⁷Sr/⁸⁶Sr同位素比值进行了正态性验证、置信区间分析、方差分析和事后多重比较。结果表明：TIMS技术测定进口大麦⁸⁷Sr/⁸⁶Sr同位素比值日内精密度和日间精密度分别达到0.003 59%和0.010 20%;不同进口国的大麦样本⁸⁷Sr/⁸⁶Sr同位素比值成正态分布，置信区间分析、方差分析以及事后多重比较都显示不同进口国大麦⁸⁷Sr/⁸⁶Sr同位素比值间具有显著性差异，可以利用TIMS测定大麦中的⁸⁷Sr/⁸⁶Sr同位素比值并进行进口国溯源。     

淹水还原条件对不同土壤中镧形态分布的影响

以旱作条件为参照,研究淹水还原条件对镧形态分布的影响。结果表明:淹水还原条件对内源镧B1态:水溶态、可交换态与碳酸盐结合,B2态:铁锰氧化物结合态,B3态:有机质及硫化物结合态的分布没有显著影响;对于外源镧,B1和B3态受淹水条件影响较大,相对于旱作条件,其浓度有增加的现象,淹水条件下B2态在中性土壤中含量稳定,酸性土壤中含量下降,而碱性土壤中含量则上升,产生变化的具体机制还有待进一步研究。两种模拟条件下外源镧3种形态的分布未达到显著性差异。不论在旱作还是淹水条件下,3种土壤中外源镧各形态浓度顺序相同,B1和B2态为:黄红壤黄褐土砂姜黑土,B3态为:砂姜黑土黄褐土黄红壤;两种模拟条件下,3种土壤中的外源镧有进入残渣态的趋势,但并不明显,且不同土壤的各形态对残渣态的贡献不同。     

激光烧蚀-多接收电感耦合等离子体质谱法测定铀颗粒物中铅杂质的同位素比值

为有效获取铀颗粒物中具有取证价值的铅杂质同位素信息,建立了激光烧蚀-多接收电感耦合等离子体质谱(LA-MC-ICP-MS)测定铀颗粒物中铅杂质同位素比值的方法.探究了诸多同位素分馏效应校正方法下铅本底对同位素测量的影响,选用的LA-MC-ICP-MS系统的本底对比值测量结果的影响小于0.001(208Pb的信号强度大于2.2× 103 cps),确定采用NIST SRM612为外标校正质量分馏,固定激光束斑直径30μm、脉冲重复率20 Hz、调节能量密度使LA-MC-ICP-MS分析NIST SRM612和铀颗粒物样品所得208Pb分别小于1.5×105 cps和3×104 cps,标准物质CRM124-4样品中206Pb/208Pb、206Pb/207Pb和207Pb/208Pb比值测量结果的相对实验标准不确定度小于0.48％、0.68％和0.40％.实际样品分析结果表明,本方法可有效区分铀颗粒物中的铅同位素比值差异,有助于鉴别其来源.     

ICP-MS测定土壤中铅同位素比值及地域差异性比较

建立用HNO_3-H_2O_2-HF体系微波消解前处理样品,利用电感耦合等离子体质谱测定土壤中铅同住素比值的方法,探讨并优化了影响测试结果的两种干扰因素.该方法中~(207)Pb/~(206)Pb和~(208)Pb/~(206)Pb的短期测量稳定性RSD分别达到0.12%和0.13%,长期测量的偏差分别在0.002和0.01以内,样品测量的最佳范围是10～40μg/L.采用标样-样品交叉法测定了湖南、湖北、云南、贵州、河南、福建、辽宁7个省的48个地区土壤中的铅同位素比值,结合聚类分析和主成分分析比较了各省土壤中同位素分布的差异,初步探讨了利用~(207)Pb/~(206)Pb和~(208)Pb/~(206)Pb比较烟叶产区的可能性.     

Isotopic Characterization of Lead in the Scottish Upland Environment

Abstract

Experimental plots have been set up at two Research Stations in upland areas of Scotland with the intention of characterising environmental samples using lead isotopic composition which varies according to the original source of the lead. Thermal ionisation mass spectrometry (TIMS) was used to measure lead isotope ratios with high precision. The ²⁰⁶Pb/²⁰⁷Pb ratios in rainwater were in the range from 1.101 to 1.153 over a period of two years at the two sites. Low ratios were associated with the very low ratios found in Britain in petrol additives during that period whereas higher ratios indicated a larger component derived from industrial sources at the Hartwood site. The ²⁰⁶Pb/²⁰⁷Pb ratios in the surface (0–2.5 cm) soil from a roadside plot were low (1.1126 and 1.1159 in 1989 and 1990, respectively) but the ratios in surface soils in plots distant from the road were considerably higher. Whereas the lead in roadside soil had a ²⁰⁶Pb/²⁰⁷Pb ratio indicating its source to be predominantly in recent petrol lead, there were significant components from other sources in the soils away from the road. The washing of grass samples resulted in no significant change in the lead isotope ratios. The lead isotope ratios measured in grass samples reflect the isotopic character of current atmospheric inputs but those in surface soil samples are an integrated record of atmospheric deposition over a long period of time. An undisturbed plot under a tree canopy had high concentrations of lead in the surface soil and low ²⁰⁶Pb/²⁰⁷Pb ratios. The ratios in fallen leaves on this plot were slightly but significantly lower than those in the grass grown on the plot. It would appear that the tree canopy is effective at scavenging lead carried in the atmosphere.     

Lead isotopic compositions of environmental certified reference materials for an inter-laboratory comparison of lead isotope analysis.

Lead isotope ratios, viz. 207Pb/206Pb and 208Pb/206Pb, of the commercially available certified reference materials (CRMs) issued in Japan are presented with an objective to provide a data set, which will be useful for the quality assurance of analytical procedures, instrumental performance and method validation of the laboratories involved in environmental lead isotope ratio analysis. The analytical method used in the present study was inductively coupled plasma quadrupole mass spectrometry (ICPQMS) preceded by acid digestion and with/without chemical separation of lead from the matrix. The precision of the measurements in terms of the relative standard deviation (RSD) of triplicated analyses was 0.19% and 0.14%, for 207Pb/20Pb and 208Pb/206Pb, respectively. The trueness of lead isotope ratio measurements of the present study was tested with a few CRMs, which have been analyzed by other analytical methods and reported in various literature. The lead isotopic ratios of 18 environmental matrix CRMs (including 6 CRMs analyzed for our method validation) are presented and the distribution of their ratios is briefly discussed.     

Evaluation of extraction/digestion techniques used to determine lead isotopic composition in forest soils

Lead isotopic studies in soils provide an efficient tool for tracing the sources of lead pollution. Five different extraction/digestion techniques (0.05 M EDTA, 0.5 M HNO₃, 2 M HNO₃, aqua regia, total digestion) were used for lead isotopic composition (²⁰⁶Pb/²⁰⁷Pb) determination in three forest soil profiles with different kinds of prevailing Pb contamination (unpolluted area, smelting area and vicinity of a motorway). The results obtained showed that all extraction/digestion methods used for the determination of ²⁰⁶Pb/²⁰⁷Pb ratios in surface horizons containing high organic matter contents gave statistically identical values (according to the Tukey test). In mineral soil horizons, differences between the individual extraction/digestion methods could be observed (the lowest ²⁰⁶Pb/²⁰⁷Pb ratios were obtained from EDTA extracts, corresponding to weakly bound anthropogenic lead, and the highest ²⁰⁶Pb/²⁰⁷Pb ratios were obtained from total digestion). The combination of total digestion and EDTA extraction (labile lead fraction) seems to be the optimal combination for ²⁰⁶Pb/²⁰⁷Pb ratio determination and optimal result interpretation.     

Isotopic precision for a lead species (PbEt4) using capillary gas chromatography coupled to inductively coupled plasma-multicollector mass spectrometry

Precision and accuracy of lead isotope ratios of a volatile lead species (PbEt₄) were determined by coupling a capillary GC to a magnetic sector multicollector ICP-MS. PbEt₄ was prepared by ethylation of a certified lead isotope solution (NIST SRM 981). Coupling was achieved by a transfer line, which allowed simultaneous introduction of a thallium standard solution to correct for mass discrimination. Seven isotopes (²⁰²Hg, ²⁰³Tl, ²⁰⁴Pb, ²⁰⁵Tl, ²⁰⁶Pb, ²⁰⁷Pb, ²⁰⁸Pb) were monitored simultaneously with a transient resolution of 50 ms. Pb isotope ratios for the PbEt₄ peaks were calculated using transient peak integrals of each isotope signal. Absolute detection limits were 20 (²⁰⁴Pb), 0.7 (²⁰⁶Pb), 1 (²⁰⁷Pb) and 0.3 pg (²⁰⁸Pb). Precision was assessed for five replicate injections of PbEt₄ in iso-octane, corresponding to a total amount of 300 pg of Pb. Precision of isotope ratios for ²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb were better than 0.07% (RSD), with ratios including ²⁰⁴Pb being one order of magnitude worse. Accuracy using mass bias correction via ²⁰³Tl/²⁰⁵Tl ranged from 0.18% for ²⁰⁸Pb/²⁰⁶Pb to 0.9% for ²⁰⁸Pb/²⁰⁴Pb.     

Precise and accurate determination of lead isotope ratios in mining wastes by ICP-QMS as a tool to identify their source

A methodology for a precise and accurate determination of lead isotope ratios in mining wastes by inductively coupled plasma quadrupole-based mass spectrometry (ICP-QMS) has been developed. The study of instrumental bias factors led to the conclusion that internal correction to compensate mass discrimination is required as well as an interference equation correction when Hg is present. The proposed method has been applied to determine lead isotope ratios in several mining wastes, soils and sediments collected at three mining areas in Spain (Aran Valley, Cartagena and Osor).Statistical analysis highlights that ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb lead isotope ratios can be used as a fingerprint of mining waste origin which is related to the geological age of the lead ore.On the other hand, no statistically significant isotopic differences between original ore samples (galena) and processing wastes within a mining district were found, corroborating a unique lead source. Moreover, the lead isotopic composition of soil and sediment samples collected at the studied mining areas is close to that determined in the mining tailings from the same areas, suggesting that the unusual high content of lead in these samples is derived from mining activities rather than from other lead sources.     

<Superscript>206</Superscript>Pb/<Superscript>207</Superscript>Pb ratios in dry deposit samples from the Metropolitan Zone of Mexico Valley

²⁰⁶Pb/²⁰⁷Pb isotope ratios of dry deposit samples in the Metropolitan Zone of Mexico Valley (MZMV) were determined and correlated with some contemporary environmental material such as gasoline, urban dust, etc., as possibile pollution sources, the latter presenting different signatures ²⁰⁶Pb/²⁰⁷Pb ratios were determined in samples “as is” by ICP-MS, using an Elan-6100. A standard material NIST-981 was used to monitor accuracy and to correct mass fractionation. The calculated enrichment factors of lead (taking rubidium as a conservative endogenous element) show its anthropogenic origin with percentages higher than 97.65%. ²⁰⁶Pb/²⁰⁷Pb ratio in dry deposit samples ranges from 0.816 to a maximum of 1.154, following a normal distribution. Arithmetic mean was 0.9967±0.0864 lower than those of possible pollution sources: 1.1395±0.0165 for gasoline, 1.071±0.008 for industrially derived lead and, for the more radiogenic natural soil and urban dust values ranging from 1.2082±0.022 to 1.211±0.108. The possible origin of lead in gasoline used prior to 1960 is discussed.     

电感耦合等离子体质谱法测定黄沙土壤中铅同位素比

用电感耦合等离子体质谱法（ＩＣＰ—ＭＳ）测定了５个黄沙原土样品中铅同位素比２０７Ｐｂ／２０６Ｐｂ、２０８Ｐｂ／２０６Ｐｂ，样品来自被认为是黄沙气溶胶源地区，为了使铅同位素测量中质量偏差和漂移减至最少，在样品中加入了铊标准溶液，测量２０５Ｔｌ／２０３Ｔｌ比，校正质量数差别选择的影响．同时，采用ＩＣＰ—ＭＳ和电感耦合等离子体原子发射光谱法（ＩＣＰ一ＡｌＳ）测定了随粒径变化样品中１２种元素浓度的变化．     

四极杆电感耦合等离子体质谱法测定沉积物中Pb稳定同位素比率研究

本文采用四极杆电感耦合等离子体质谱法测定了玄武湖和莫愁湖,及其相连的河道表层沉积物中Pb稳定同位素的比率.沉积物中208Pb/206Pb和206Pb/207Pb的比率范围分别为2.0931～2.1239和1.1558～1.1845.玄武湖、莫愁湖、护城河等采样点Pb稳定同位素比率,与文献中长江江苏段沉积物相近.其它河道采样点Pb稳定同位素组成与文献中南京市大气、土壤Pb稳定同位素比率相近.