负热电离同位素稀释质谱法分析锝97稀释剂

用负热电离质谱法对自行研制生产的97Tc稀释剂同位素组成进行分析测定,并采用同位素稀释质谱法对其浓度进行标定,选用等概率模型对同位素比值测定结果进行校正,组成分析扩展不确定度为1.3%(K=2),浓度标定扩展不确定度为2.07%(K=2)。     

气相色谱法测定地下水多环芳烃准确度的保证措施

针对环境中常见且对人体危害极大的USEPA优先控制污染物16种多环芳烃(PAHs)在地下水中的监测方法进行了研究,主要从影响方法准确度的空白溶剂的选择、标准样品测定、基质加标回收率方面进行了实验研究,利用数理统计的t 检验进行显著性检验,并对研究区水中的多环芳烃进行了测定。结果表明,该方法宜选用市售纯净水做空白溶剂,基质加标回收率在71 5%~99 7%范围内,标准样品测定的相对误差在1 0%~17 2%;经系统误差检验确定本方法不存在系统误差,可以达到测定地下水中多环芳烃的目的。实际样品的测定结果说明煤矸石中的多环芳烃随降水淋滤以及酸性矿坑排水进入地下水和地表水的可能性是存在的,其迁移转化机理需进一步深入研究。     

波阻抗反演方法在塔河碳酸盐岩储层预测中的应用

详细分析了约束稀疏脉冲反演、地震特征反演以及随机反演3种反演算法及其特点,针对塔河油田碳酸盐岩储层进行了反演试算对比.研究结果表明,约束稀疏脉冲反演结果与地震反射资料特征有较好的对应关系,但其反演结果分辨率不高.随机反演能客观地描述碳酸盐岩缝洞型储层非均质性极强的分布特征,克服了其他反演结果存在连续性、成层性的缺陷,但该方法难以求取准确的变差函数.3种反演结果中,地震特征反演结果与井史储层发育段的吻合率最高,说明地震特征反演在塔河奥陶系碳酸盐岩储层预测中仍然是一种较好的方法.     

地震检波器的横向灵敏度特性

地震检波器受到地面横向运动激励时的输入输出关系定义为检波器的横向灵敏度特性.本文对检波器线圈受到横向激励时产生的轴向振动进行了分析.可以看到,当悬挂线圈的弹簧片悬丝发生动力失稳时,检波器的横向灵敏度突然增大;在线圈横向振幅很小的情况下,失稳频率接近悬丝的横向固有频率.利用谱分析技术可以准确地从检波器噪声中检测出检波器的横向灵敏度和失稳频率,即检波器假频.     

Stable W Isotope Measurements of Geological Reference Materials and Tungsten Ore Minerals by Double Spike MC-ICP-MS

This study presents high-precision W isotopic measurement results using the ¹⁸⁰W-¹⁸³W double spike technique with MC-ICP-MS. The effects of isobaric and polyatomic interferences on W isotopic measurements were evaluated. The δ^186/184W values were not significantly affected when the solution had Hf/W ≤ 3 × 10^-4, Ta/W ≤ 1, Os/W ≤ 0.06, Ce/W ≤ 0.0075, Nd/W ≤ 3.5 and Sm/W ≤ 5. The intermediate measurement precisions of both standard solutions (NIST SRM 3163 and Alfa Aesar W) and geological reference materials (NOD-A-1) were better than ±0.024‰ (2s). We also obtained a precision of 0.026‰ for a minimum sample loading mass of 5 ng, allowing the analysis of samples with low W contents. Replicated measurements of geological reference materials (AGV-2, BCR-2, BHVO-2, GSP-2, RGM-1, SDC-1, NOD-A-1 and NOD-P-1) yielded δ^186/184W values ranging from 0.017‰ to 0.144‰. The δ^186/184W values of two major tungsten ore minerals (scheelite and wolframite) were reported and compared herein. Scheelites had systematically slightly heavier W isotopic compositions than wolframites, which may reflect differences in the crystal structure. The resolvable variations of stable/mass-dependent W isotopic compositions in rocks and ore minerals make W isotopes a novel tool for studying hydrothermal mineralisation processes and the W cycle of geological reservoirs.     

Combined Separation of Cu,Fe and Zn from Rock Matrices and Improved Analytical Protocols for Stable Isotope Determination

Isotope ratios of heavy elements vary on the 1/10000 level in high temperature materials, providing a fingerprint of the processes behind their origin. Ensuring that the measured isotope ratio is precise and accurate depends on employing an efficient chemical purification technique and optimised analytical protocols. Exploiting the disparate speciation of Cu, Fe and Zn in HCl and HNO₃, an anion exchange chromatography procedure using AG1‐×8 (200–400 mesh) and 0.4 × 7 cm Teflon columns was developed to separate them from each other and matrix elements in felsic rocks, basalts, peridotites and meteorites. It required only one pass through the resin to produce a quantitative and pure isolate, minimising preparation time, reagent consumption and total analytical blanks. A ThermoFinnigan Neptune Plus MC‐ICP‐MS with calibrator‐sample bracketing and an external element spike was used to correct for mass bias. Nickel was the external element in Cu and Fe measurements, while Cu corrected Zn isotopes. These corrections were made assuming that the mass bias for the spike and analyte element was identical, and it is shown that this did not introduce any artificial bias. Measurement reproducibilities were ± 0.03‰, ± 0.04‰ and ± 0.06‰ (2s) for δ⁵⁷Fe, δ⁶⁵Cu and δ⁶⁶Zn, respectively.     

IsoSpike: Improved Double‐Spike Inversion Software

The double‐spike approach for correction of instrumental mass bias in mass spectrometry data is well established. However, there is very little consistency within the scientific community in terms of double‐spike data reduction. Double‐spike solutions require computer calculation, using either geometric or algebraic approaches, and are often performed using spreadsheet calculations that vary from group to group and between isotope systems. Here, we present IsoSpike, a generalised computer procedure for the processing of double‐spike mass spectrometry data, built as an add‐on for the Iolite data‐reduction package ( www.iolite.org.au ). Use of this software permits visualisation of mass spectrometry data in a time window, and rigorous treatment and screening of data. Additionally, IsoSpike uses an integration‐by‐integration approach where the double‐spike calculations are performed on every integration within an analysis, providing straightforward quantification of uncertainties on double‐spike‐corrected isotope ratios. The advantages of this approach over traditional methods are discussed here. Platinum stable isotope data are presented as an example data set, although the procedure is applicable to any double‐spike system. IsoSpike is freely available from www.isospike.org .     

Application of an impact plate – Bedload transport measuring system for high-speed flows

To achieve the sustainable use of dams, the development of methods for sediment management in reservoirs is required. One such method includes the use of Sediment Bypass Tunnels (SBTs) to divert sediment around a dam, thereby preventing sedimentation in the reservoir. However, SBTs are prone to severe invert abrasion caused by the high sediment flux. Therefore, it is necessary to establish a measurement system of the sediment transport rate in these tunnels. One system to measure sediment transport in rivers is the Swiss plate geophone, which can register plate vibrations caused by particle impact. In Japan, the Japanese pipe microphone is used, and sediment transport is measured based on the sound emitted by the particle impact. In this study an attempt was made to optimize the advantages of both systems by fixing a microphone and an acceleration sensor to a steel plate. The results of calibration experiments with this new system are presented and compared with the existing methods. It was found that the acceleration sensor can detect sediment particles larger than 2 mm in diameter. Moreover, a new parameter, referred to as the detection rate, was introduced to describe the correlation between the actual amount of sediment and the registered output. Finally, two parameters - the saturation rate and hit rate - are introduced and exhibit strong correlation with the detection rate.     

铅同位素"双稀释剂"同位素定年法计算方法研究

铅同位素研究已广泛应用于模式定年、成矿物质来源示踪和化探找矿评价等许多领域。铅同位素“双稀释剂”同位素定年法是当前应用较广的一种铅同位素定年方法。双同位素稀释法的目的在于校正质量鉴别效应,提高测定精度。由于实验条件和分析技术的改善和提高,使铅同位素“双稀释剂”测定精度和准确度大大提高,从而铅同位素“双稀释剂”同位素定年法也将得到更为广泛的应用。本主要是研究该法的计算,分析样品中元素量的计算,并结合几种岩石年龄方法(Pb-Pb等时线法、不一致线模式计算法、三阶段模式计算等)的计算,归纳总结出计算样品中元素量和岩石形成年龄的方法。     

太阳微波尖峰辐射的高时间、高频率分辨率偏振观测

利用北京天文台 ２．６—３．８ ＧＨｚ频谱仪的观测资料,找到 １１个微波尖峰辐射事件．尖峰一般具有数十毫秒的寿命,数百个ｓｆｕ的流量密度和数十至数百ＭＨｚ的带宽,这与以前的报道类似．尖峰的偏振度各式各样,有的尖峰还有数千ＭＨｚ／ｓ的频率漂移．某些尖峰在二个偏振态之间有８毫秒的时间延迟（最大延迟可达１６毫秒）．另外,还发现了尖峰的偏振度随频率剧烈变化的偏振反转现象．