共查询到20条相似文献,搜索用时 46 毫秒
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地质样品中卤素是反演与流体和挥发分相关的地质过程的重要示踪元素.由于卤素含量低和强挥发性,准确测定地质样品中卤素一直是分析地球化学的难点.近年来,针对地质样品卤素的样品前处理技术的开发开展了大量工作.高温热解法、碱熔(溶)法、酸性消解法和碱性提取法能够满足土壤、沉积物和岩石中高含量卤素的分析要求.针对低含量卤素,仅有中子活化法和稀有气体质谱法能够准确定量.随着分析地球化学的发展,地质样品卤素分析技术逐渐向更高效的消解方法、更简便的操作以及更高灵敏度和高精度的分析方向改进.总结了近年来国内外在地质样品卤素分析方面所取得的成果,对比了各类方法的优缺点,展望了地质样品卤素分析方法的发展前景. 相似文献
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Hélène Balcone‐Boissard Agnès Michel Benoît Villemant 《Geostandards and Geoanalytical Research》2009,33(4):477-485
Concentrations of halogens (fluorine, chlorine, bromine and iodine) were determined in six geochemical reference materials (BHVO‐2, GS‐N, JG‐1, JR‐1, JB‐1b, JB‐2). Halogens were first extracted from powdered samples using a pyrohydrolysis technique, then hydrolysis solutions were analysed by ion chromatography for F and Cl and inductively coupled plasma‐mass spectrometry for Br and I. The detection limits in solutions were 100 μg l?1 for both F and Cl and 10 ng l?1 for Br and I. Considering the extraction procedure, performed on a maximum of 500 mg of sample and producing 100 ml of pyrohydrolysis solution, detection limits in rock samples were 20 mg kg?1 for F and Cl and 2 μg kg?1 for Br and I. The mean analytical errors on the studied composition ranges were estimated at 10 mg kg?1 for F and Cl, 100 μg kg?1 for Br and 25 μg kg?1 for I. The concentration values, based on repeated (generally > 10) sample analysis, were in good agreement generally with published values and narrowed the mean dispersion around mean values. Large dispersions are discussed in terms of samples heterogeneity and contaminations during sample preparation. Basaltic RMs were found to be more suitable for studies of halogen compositions than differentiated rock material, especially granites – the powders of which were heterogeneous in halogens at the 500 mg level. 相似文献
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Marcel LANGENAUER Urs KRÄHENBÜHL Verena FURRER Armin WYTTENBACH 《Geostandards and Geoanalytical Research》1992,16(1):41-44
The concentrations of fluorine, chlorine, bromine and iodine of seven geochemical reference samples have been determined. Analytical techniques were neutron activation analysis for chlorine, bromine and iodine and ion-selective potentiometry for fluorine. After irradiation of the samples, these halogens were separated from the matrix elements by pyrohydrolysis in presence of vanadium (V) oxide. This extraction allows to measure the four halogens in the same sample. 相似文献
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R. Fuge 《Contributions to Mineralogy and Petrology》1977,61(3):245-249
The behaviour of fluorine and chlorine during differentiation is considered in the light of halogen data for granites and separated biotites from the Dartmoor granite pluton of S.W. England, hornblende-bearing ultrabasic and basic rocks from a layered intrusion at Rhiw, N. Wales, and recent literature data on halogens in apatites from the Shonkin Sag laccolith and the Skaergaard intrusion.The data indicate that whereas fluorine concentrations are highest in the late stage differentiates, chlorine concentration is highest in the earlier differentiates. It is suggested that this behaviour of the two halogens is due to their relative affinities for silicate melts. Chlorine having a low solubility in silicate melts and a strong affinity for associated aqueous phases will tend to be concentrated in early formed hydrous minerals, leaving fluorine with its strong affinity for the melt to be enriched in the late-formed hydrous minerals. 相似文献
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《International Geology Review》2012,54(12):1795-1797
At 500–600°C and 500–800 atm, in alkaline solutions, two mechanisms of the migrations of Ti, Zr, and Hf are experimentally indicated: a) in the absence of fluorine and other halogens, these metals migrate as titanates, zirconates, and hafnates of K and Na, the forms which are conducive to their dissipation but not deposition-accumulation in the rocks, within a wide range of temperature, as long as the pH of the solution remains alkaline; b) in the presence of fluorine, Ti, Zr, and Hf migrate as fluoride complexes (with Na and K) from which they may be liberated by hydrolysis and deposited at decreasing temperature, as the corresponding oxides. 相似文献
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Tao He Mufei Li Zhaochu Hu Wen Zhang Haihong Chen Zaicong Wang Yongsheng Liu 《Geostandards and Geoanalytical Research》2023,47(1):155-168
The lack of analytical techniques for halogens in geological materials is mainly due to the loss of analytes during sample preparation. This study describes a rapid bulk rock digestion method (NH4F digestion) for determination of the abundances of Cl, Br and I in geological materials by SF-ICP-MS. During high temperature (200–240 °C) digestion, NH3 released from the decomposition of molten NH4F can effectively prevent the loss of halogens released from geological samples. Chlorine, Br and I were not lost during NH4F digestion at 220 °C for 0.25–6 h. The limits of quantitation for NH4F digestion were 2.8, 0.018 and 0.003 μg g-1 Cl, Br and I, respectively. Most results for halogens in geological reference materials by NH4F digestion were in agreement with their certified values, confirming that the high-performance rapid bulk rock NH4F digestion has sufficient digestion capability to extract Cl, Br and I from rocks, sediments and soils. In comparison, results obtained following acid digestion showed that HNO3 + HF digestion could effectively extract Br and I from soil and sediment samples, and that HNO3 acid digestion is only suitable to use for the determination of Br and I in soil samples. 相似文献
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Halogen diffusion in a basaltic melt 总被引:2,自引:0,他引:2
The diffusion of the halogens fluorine, chlorine and bromine was measured in a hawaiitic melt from Mt. Etna at 500 MPa and 1.0 GPa, 1250 to 1450 °C at anhydrous conditions; the diffusion of F and Cl in the melt was also studied with about 3 wt% of dissolved water. Experiments were performed using the diffusion-couple technique in a piston cylinder. Most experiments were performed with only one halogen diffusing between the halogen-enriched and halogen-poor halves of the diffusion couple, but a few experiments with a mixture of halogens (F, Cl and Br) were also performed in order to investigate the possibility of interactions between the halogens during diffusion. Fluorine and chlorine diffusivity show a very similar behavior, slightly diverging at low temperature. Bromine diffusion is a factor of about 2-5 lower than the other halogens in this study. Diffusion coefficients for fluorine range between 2.3 × 10−11 and 1.4 × 10−10 m2 s−1, for chlorine between 1.1 × 10−11 and 1.3 × 10−10 and for bromine between 9.4 × 10−12 and 6.8 × 10−11 m2 s−1. No pressure effect was detected at the conditions investigated. In experiments involving mixed halogens, the diffusivities appear to decrease slightly (by a factor of ∼3), and are more uniform among the three elements. However, activation energies for diffusion do not appear to differ between experiments with individual halogens or when they are all mixed together. The effect of water increases the diffusion coefficients of F and Cl by no more than a factor of 3 compared to the anhydrous melt (DF = 4.0 × 10−11 to 1.6 × 10−10 m2 s−1; DCl = 3.0 × 10−11 to 1.9 × 10−10 m2 s−1). Comparing our results to the diffusion coefficients of other volatiles in nominally dry basaltic melts, halogen diffusivities are about one order of magnitude lower than H2O, similar to CO2, and a factor of ∼5 higher than S. The contrasting volatile diffusivities may affect the variable extent of volatile degassing upon melt depressurization and vesiculation, and can help our understanding of the compositions of rapidly grown magmatic bubbles. 相似文献
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苯系污染物(苯、甲苯、乙苯和二甲苯)是环境中重点优先监测的致癌污染物。文章介绍了近年来国内外在水环境中苯系污染物的分析研究进展,内容主要包括:胶束电动毛细管色谱法(MECC)、吹扫捕集-气相色谱法(PT-GC)、吹扫捕集-气相色谱-质谱联用法(PT-GC-MS)、顶空固相微萃取(HS-SPME)-便携式微火焰离子化(portable GC-μFID)等联测分析技术与方法。 相似文献
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应用吹扫捕集-气相色谱-质谱法测定岩溶地区垃圾渗透液中36种挥发性有机物(VOCs)的含量。获取样品溶液5 mL于吹扫瓶中,利用TELEDYNE TEKMAR型吹扫捕集直接进样,经DB-VRX毛细管色谱柱分离、电子轰击电离(EI)全扫描检测,选择特征离子,再用外标法进行定量测定。结果表明:36种挥发性有机物的质量浓度在1~100 μg·L-1 范围内,与其峰面积呈线性关系,方法检出限在0.03~0.27 μg·L-1 之间,加标回收率在88%~110%之间,相对标准偏差(n=7)在2.32%~6.51%之间。 相似文献
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A vertical-slot sand trap was constructed incorporating a device to adjust the freedom of flow through the trap. Using a dune-sand of equivalent diameter 0.25 mm, measurements of sand transport were made with this flow so adjusted that no change of sand surface geometry detectable by eye occurred upstream of the trap; this was considered to be a correct procedure. Further measurements were taken with the flow through the trap deliberately set to be (a) more vigorous and (b) less vigorous than the correct setting. In the latter case very significant differences were observed in measured transport rates of sand compared with the ‘correct’measurements. The disparities are of interest because it is commonly assumed that sand grains have enough ‘penetration’to enter a slot trap freely despite a degree of stagnation upstream of it. This does not appear to be a prudent assumption and substantial errors may result from lack of attention to the provision of free air flow through the trap. 相似文献
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岩性圈闭地质风险评价原则与方法探讨 总被引:2,自引:0,他引:2
依据对油气勘探理论和圈闭概念的理解和认识,认为在建立岩性圈闭地质模型时,对岩性圈闭的地质风险评价应分3个层次进行,即圈闭的成藏环境、圈闭自身的成藏条件和圈闭可靠性的评价,从而得到圈闭的含油气性系数或圈闭的地质风险系数.在分析圈闭自身的成藏条件时,应对传统的"生、储、盖、运、圈、保"进行分类和归纳,利用圈闭获得油气的能力、圈闭的储集能力、圈闭的后期保存条件"三要素"对岩性圈闭的含油气性进行评价.运用该评价系统对西部新区塔里木、准噶尔盆地中的储备圈闭进行了评价,其评价结果均较合理. 相似文献
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渤海湾盆地南堡凹陷断层对油气运聚的控制作用 总被引:4,自引:1,他引:3
在对南堡凹陷断层类型划分的基础上,利用地质统计法和地化分析等技术手段,从宏观到微观多个方面阐述了南堡凹陷断层对油气运聚的控制作用。根据断层的发育历史,将南堡凹陷断层划分为3类:长期活动型(Ⅰ类)、早期活动型(Ⅱ类)和晚期活动型(Ⅲ类)。其中Ⅰ类断层大多沟通油源,是油气纵向运移的主要通道,由于其多期活动,形成了南堡凹陷多套含油层系纵向上相互叠置的局面。断层活动的时期和强度控制油气纵向上的分配,而且油气在平面上主要分布在油源断层附近的断块圈闭中。断层封闭性在时间上具有明显的差异性,在油气运聚过程中扮演输导和封堵双重角色。反向遮挡断层圈闭无论在油气藏数量还是在烃柱高度方面均明显好于顺向断层遮挡圈闭,是南堡凹陷油气勘探的有利目标。断层遮挡圈闭的储量规模受断层封闭性影响,准确评价遮挡断层的封闭能力对于提高钻探成功率具有重要意义。 相似文献
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目前隧道及大型地下工程往往在裂隙岩体中开挖,而裂隙与地下空间的距离及裂隙的扩展条件,制约着隧道及地下工程的稳定性。应用能考虑孔洞和裂纹问题的新型边界积分方程与无网格加辽金法结合,建立一种新型的边界无单元法。在该方法中基本的未知量是由边界上的面力和边界上位移密度函数构成的复变量边界函数 。文中应用的边界积分公式和Muskhelishvili的积分公式直接相关。将无网格构造方法引入新型的边界积分方程,建立了新型的边界无单元法。应用该方法详细分析了含隧道和裂纹间相互关系等问题,其数值结果与解析结果吻合很好,说明该方法的正确性和可行性。 相似文献
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J. K. McCormack 《Mineralium Deposita》2000,35(8):796-798
Most cinnabar is brilliant red and remains so under sunlight. However, some cinnabar is photosensitive and irreversibly blackens
during exposure to sunlight. Electron microprobe analyses of cinnabar from several occurrences show that photosensitive cinnabar
contains noteworthy concentrations of chlorine, whereas non-photosensitive cinnabar does not. Experimental evidence shows
that non-photosensitive cinnabar becomes photosensitive after exposure to halogens. The darkening of cinnabar in sunlight
is caused by the presence of contained chlorine or other halogens.
Received: 6 April 2000 / Accepted: 28 July 2000 相似文献