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1.
使用粉末压片-X射线荧光光谱法测定地质样品中的Cl和S,探讨了样品放置时间、环境以及建立真空的时间对测量结果的影响。Cl的精密度(RSD,n=6)小于10%,S的精密度(RSD,n=6)小于5%。Cl和S的方法检出限分别为14和11μg/g,采用国家标准物质分析验证方法,其结果与标准值相符。  相似文献   

2.
中子活化分析方法测量金的活动态   总被引:3,自引:1,他引:3  
探讨了金的活动态各相态(水浸出态,粘土吸附态,有机链合态,铁锰氧化物态)提取操作和中子活化分析测定的条件。列出了部分样品中金活动态分析结果和其测定精度范围,各相态的空白值和RSD(n=5)分别为:水浸出态0.030ng/g,4.5%-26.0%;粘土吸附态0.05ng/g,11.6%-25.2%;有机链合态0.06ng/g,3.7%-26.8%;铁锰氧化物态0.05ng/g,5.9%-31.6%。  相似文献   

3.
原子吸收光谱法测定土壤和水系沉积物中的银   总被引:1,自引:1,他引:0  
样品经四酸分解,1%的硝酸提取,2%硫脲定溶。石墨炉原子吸收测定样品中的银,方法检出限0.014ug/g,精密度(RSD,n=6)4%~16%;回收率为96%~104%。方法经国家一级标准物质验证,测定结果与标准值相符。  相似文献   

4.
杜淑兰 《吉林地质》2010,29(4):106-107,119
使用粉末压片法制样,X射线荧光光谱法测定地质样品中氯,探讨了样片背衬、样片接受X光照射时间对测量结果的影响。Cl的精密度(RSD,n=12)小于10%。Cl的方法检出限为12μg/g,采用国家一级标准物质分析验证方法,其结果与标准值相符。  相似文献   

5.
用模拟卤水建立一套能量色散X射线荧光光谱法测定卤水中硫氯钾钙主量元素含量的方法。结果表明,方法连用于高盐度卤水的测试分析,一定浓度的Mg对测定结果没有明显的影响。方法的分析精密度(RSD,n=15)为0.97%~4.16%(除Ca外),检出限为S0.030g/L、C10.015g/L、K0.020g/L和Ca0.008g/L。卤水中S、Cl、K的测定结果与相应的重量法、滴定法、原子吸收光谱法结果相符。  相似文献   

6.
介绍了在Fe^3 存在下于ψ为5%-10%王水中用泡沫塑料吸附Au,12g/L硫脲溶液解脱,以抗坏血酸作为基体改进剂,采用最大功率升温和长寿命石墨管技术进行勘查地球化学样品中超痕量金的石墨炉原子吸收光谱测定方法。方法检出限为0.04ng/g。精密度(RSD,n=12)为8.44%-11.5%,经国家一级标准物质分析验证,结果与标准值符合。  相似文献   

7.
发射光谱法测定勘查地球化学样品中银硼锡钼铅   总被引:21,自引:13,他引:21  
张雪梅  张勤 《岩矿测试》2006,25(4):323-326
以K2S2O7、NaF、Al2O3和炭粉为缓冲剂,Ge为内标,电弧发射光谱法测定勘查地球化学样品中Ag、B、Sn、Mo、Pb。方法检出限为Ag0.013μg/g、B0.83μg/g、Sn0.23μg/g、Mo0.073μg/g、Pb0.37μg/g。方法精密度(RSD,n=12)为Ag4.2%~11.3%、B3.2%~6.5%、Sn2.6%~7.1%、Mo2.9%~6.3%、Pb1.57%~5.18%。测定了国家一级地球化学标准物质,结果与标准值相符。  相似文献   

8.
发射光谱法快速测定银锡铜铅锌钼铍   总被引:4,自引:9,他引:4  
叶晨亮 《岩矿测试》2004,23(3):238-240
使用两台摄谱仪同时接收光谱,以K2S2O7、NaF、Al2O3为缓冲剂,Ge、Sb为内标,测定化探样品中7项元素,检出限(μg/g)分别是:Ag0.02,Sn0.5,Cu 1,Pb 2,Zn 10,Mo 0.2,Be 0.5;精密度(RSD,n=20)在2.9%~16.8%。采用国家一级标准物质验证方法可靠性,测定结果与标准值一致。  相似文献   

9.
陈世忠 《岩矿测试》2003,22(3):228-230
报道了以NH4H2PO4为基体改进剂,采用悬浮体制样石墨炉原子吸收光谱法直接测定琥珀中微量铅的方法。试验了影响测定的主要因素。在优化实验条件下。方法的检出限为0.038μg/g,Pb的质量浓度为0~80μg/L时,工作曲线线性关系良好。对于ω(Pb)=5.71μg/g样品的测定,相对标准偏差(RSD,n=5)为6.83%。  相似文献   

10.
多目标地球化学调查土壤样品中氮和碳的快速测定   总被引:2,自引:1,他引:2  
详细研究了元素分析仪的工作条件,建立了直接固体进样同时测定多目标地球化学调查土壤样苎支氮、碳的方法。方法简便、快速,检出限为氮14.5μg/g、碳0.013%。经土壤国家一级标准物质分析验证,测定值与标准值相符,精密度(RSD,n=12)为氮1.49%-3.27%、碳0.64%~3.63%。  相似文献   

11.
Most sulfide-rich magmatic Ni-Cu-(PGE) deposits form in dynamic magmatic systems by partial melting S-bearing wall rocks with variable degrees of assimilation of miscible silicate and volatile components, and generation of barren to weakly-mineralized immiscible Fe sulfide xenomelts into which Ni-Cu-Co-PGE partition from the magma. Some exceptionally-thick magmatic Cr deposits may form by partial melting oxide-bearing wall rocks with variable degrees of assimilation of the miscible silicate and volatile components, and generation of barren Fe ± Ti oxide xenocrysts into which Cr-Mg-V ± Ti partition from the magma. The products of these processes are variably preserved as skarns, residues, xenoliths, xenocrysts, xenomelts, and xenovolatiles, which play important to critical roles in ore genesis, transport, localization, and/or modification. Incorporation of barren xenoliths/autoliths may induce small amounts of sulfide/chromite to segregate, but incorporation of sulfide xenomelts or oxide xenocrysts with dynamic upgrading of metal tenors (PGE > Cu > Ni > Co and Cr > V > Ti, respectively) is required to make significant ore deposits. Silicate xenomelts are only rarely preserved, but will be variably depleted in chalcophile and ferrous metals. Less dense felsic xenoliths may aid upward sulfide transport by increasing the effective viscosity and decreasing the bulk density of the magma. Denser mafic or metamorphosed xenoliths may also increase the effective viscosity of the magma, but may aid downward sulfide transport by increasing the bulk density of the magma. Sulfide wets olivine, so olivine xenocrysts may act as filter beds to collect advected finely dispersed sulfide droplets, but other silicates and xenoliths may not be wetted by sulfides. Xenovolatiles may retard settling of – or in some cases float – dense sulfide droplets. Reactions of sulfide melts with felsic country rocks may generate Fe-rich skarns that may allow sulfide melts to fractionate to more extreme Cu-Ni-rich compositions. Xenoliths, xenocrysts, xenomelts, and xenovolatiles are more likely to be preserved in cooler basaltic magmas than in hotter komatiitic magmas, and are more likely to be preserved in less dynamic (less turbulent) systems/domain/phases than in more dynamic (more turbulent) systems/domains/phases. Massive to semi-massive Ni-Cu-PGE and Cr mineralization and xenoliths are often localized within footwall embayments, dilations/jogs in dikes, throats of magma conduits, and the horizontal segments of dike-chonolith and dike-sill complexes, which represent fluid dynamic traps for both ascending and descending sulfides/oxides. If skarns, residues, xenoliths, xenocrysts, xenomelts, and/or xenovolatiles are present, they provide important constraints on ore genesis and they are valuable exploration indicators, but they must be included in elemental and isotopic mass balance calculations.  相似文献   

12.
Between 1985 and 1991, two new mountain protected areas (MTNPA) covering more than 35,000 km2 and based on participatory management models — the Makalu-Barun National Park and Conservation Area, Nepal, and Qomolangma Nature Preserve, Tibet Autonomous Region — were successfully established through the collaborative efforts of Woodlands Mountain Institute and conservationists in China and Nepal. Characteristics common to both projects include the importance of establishing (1) effective rationales, (2) local support constituencies, (3) a senior advisory group, (4) a task force, (5) linkages between conservation and development, and (6) fund raising mechanisms. The lessons derived from the experiences of Woodlands Mountain Institute are of significant value to others in preserving MTNPA. Increased collaboration and communication between all interested in conservation, however, will remain a critical component for expanding mountain protected area coverage to throughout the world.  相似文献   

13.
This article advances critical geographies of youth through examining the spatiality implicit in the imagined futures of young women in rural India. Geographers and other scholars of youth have begun to pay more attention to the interplay between young people’s past, present, and imagined futures. Within this emerging body of scholarship the role of the family and peer group in influencing young people’s orientations toward the future remain underexamined. Drawing on eleven months of ethnographic fieldwork, my research focuses on a first generation of college-going young women from socioeconomically marginalized backgrounds in India’s westernmost state of Gujarat. I draw on the “possible selves” theoretical construct in order to deploy a flexible conceptual framework that links imagined post-educational trajectories with motivation to act in the present. In tracing the physical movement of these young women as they navigate and complete college, my analysis highlights the ways in which particular kinds of spaces and spatial arrangements facilitate and limit intra- and inter-generational contact, and the extent to which this affects young women’s conceptions of the future. I conclude by considering the wider implications of my research for ongoing debates surrounding youth transitions, relational geographies of age, and education in the Global South.  相似文献   

14.
The contents of As, Cd, Cu, Cr, Mg, Mn, Ni, Pb and Zn have been determined in sediment and water samples from Valle de las Garzas estuary and Port Manzanillo (Colima, Mexico) using ICP-AES. The concentrations of these elements were used for a comparative study to determine the distribution of heavy metals and to evaluate which elements reflect natural or anthropogenic backgrounds. For this purpose, seven sampling points were selected: Four of them correspond to the lagoon, and three were situated in the port. Statistical analysis of the mineral content was assessed. Initially, data comparison was assessed by statistical tests for each variable. Principal component analysis was then applied considering the influence of all variables at the same time by obtaining the distribution of samples according to their scores in the principal component space. In this way, four studies were carried out: (1) study of sediments collected during the dry season; (2) study of sediments collected during the rainy season; (3) comparative study between sediments from rainy and dry season; and (4) study of water composition collected during rainy season. From the results of the performed analyses, it can be concluded that metals distribution pattern reflected natural and anthropogenic backgrounds (e.g., sediments from the lagoon, situated at the beginning of the rain channel, presented high contents of Zn and Cu, perhaps related to anthropogenic activities or the influence of igneous sediments).  相似文献   

15.
16.
《Chemical Geology》2007,236(1-2):13-26
We examined the coprecipitation behavior of Ti, Mo, Sn and Sb in Ca–Al–Mg fluorides under two different fluoride forming conditions: at < 70 °C in an ultrasonic bath (denoted as the ultrasonic method) and at 245 °C using a Teflon bomb (denoted as the bomb method). In the ultrasonic method, small amounts of Ti, Mo and Sn coprecipitation were observed with 100% Ca and 100% Mg fluorides. No coprecipitation of Ti, Mo, Sn and Sb in Ca–Al–Mg fluorides occurred when the sample was decomposed by the bomb method except for 100% Ca fluoride. Based on our coprecipitation observations, we have developed a simultaneous determination method for B, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta by Q-pole type ICP-MS (ICP-QMS) and sector field type ICP-MS (ICP-SFMS). 9–50 mg of samples with Zr–Mo–Sn–Sb–Hf spikes were decomposed by HF using the bomb method and the ultrasonic method with B spike. The sample was then evaporated and re-dissolved into 0.5 mol l 1 HF, followed by the removal of fluorides by centrifuging. B, Zr, Mo, Sn, Sb and Hf were measured by ID method. Nb and Ta were measured by the ID-internal standardization method, based on Nb/Mo and Ta/Mo ratios using ICP-QMS, for which pseudo-FI was developed and applied. When 100% recovery yields of Zr and Hf are expected, Nb/Zr and Ta/Hf ratios may also be used. Ti was determined by the ID-internal standardization method, based on the Ti/Nb ratio from ICP-SFMS. Only 0.053 ml sample solution was required for measurement of all 9 elements. Dilution factors of ≤ 340 were aspirated without matrix effects. To demonstrate the applicability of our method, 4 carbonaceous chondrites (Ivuna, Orgueil, Cold Bokkeveld and Allende) as well as GSJ and USGS silicate reference materials of basalts, andesites and peridotites were analyzed. Our analytical results are consistent with previous studies, and the mean reproducibility of each element is 1.0–4.6% for basalts and andesites, and 6.7–11% for peridotites except for TiO2.  相似文献   

17.
Partition coefficients of Hf,Zr, and REE between zircon,apatite, and liquid   总被引:25,自引:2,他引:25  
Concentration ratios of Hf, Zr, and REE between zircon, apatite, and liquid were determined for three igneous compositions: two andesites and a diorite. The concentration ratios of these elements between zircon and corresponding liquid can approximate the partition coefficient. Although the concentration ratios between apatite and andesite groundmass can be considered as partition coefficients, those for the apatite in the diorite may deviate from the partition coefficients. The HREE partition coefficients between zircon and liquid are very large (100 for Er to 500 for Lu), and the Hf partition coefficient is even larger. The REE partition coefficients between apatite and liquid are convex upward, and large (D=10–100), whereas the Hf and Zr partition coefficients are less than 1. The large differences between partition coefficients of Lu and Hf for zircon-liquid and for apatite-liquid are confirmed. These partition coefficients are useful for petrogenetic models involving zircon and apatite.  相似文献   

18.
Models have become so fashionable that many scientists and engineers cannot imagine working without them. The predominant use of computer codes to execute model calculations has blurred the distinction between code and model. The recent controversy regarding model validation has brought into question what we mean by a ‘model’ and by ‘validation.’ It has become apparent that the usual meaning of validation may be common in engineering practice and seems useful in legal practice but it is contrary to scientific practice and brings into question our understanding of science and how it can best be applied to such problems as hazardous waste characterization, remediation, and aqueous geochemistry in general. This review summarizes arguments against using the phrase model validation and examines efforts to validate models for high-level radioactive waste management and for permitting and monitoring open-pit mines. Part of the controversy comes from a misunderstanding of ‘prediction’ and the need to distinguish logical from temporal prediction. Another problem stems from the difference in the engineering approach contrasted with the scientific approach. The reductionist influence on the way we approach environmental investigations also limits our ability to model the interconnected nature of reality. Guidelines are proposed to improve our perceptions and proper utilization of models. Use of the word ‘validation’ is strongly discouraged when discussing model reliability.  相似文献   

19.
The shape of sedimentary particles may carry important information on their history. Current approaches to shape classification (e.g. the Zingg or the Sneed and Folk system) rely on shape indices derived from the measurement of the three principal axes of the approximating tri-axial ellipsoid. While these systems have undoubtedly proved to be useful tools, their application inevitably requires tedious and ambiguous measurements, also classification involves the introduction of arbitrarily chosen constants. Here we propose an alternative classification system based on the (integer) number of static equilibria. The latter are points of the surface where the pebble is at rest on a horizontal, frictionless support. As opposed to the Zingg system, our method relies on counting rather than measuring. We show that equilibria typically exist on two well-separated (micro and macro) scales. Equilibria can be readily counted by simple hand experiments, i.e. the new classification scheme is practically applicable. Based on statistical results from two different locations we demonstrate that pebbles are well mixed with respect to the new classes, i.e. the new classification is reliable and stable in that sense. We also show that the Zingg statistics can be extracted from the new statistics; however, substantial additional information is also available. From the practical point of view, E-classification is substantially faster than the Zingg method.  相似文献   

20.
Pools,riffles, and channelization   总被引:2,自引:0,他引:2  
The addition of regularly spaced deeps (pools) and shallows (riffles) that provide a variety of flow conditions, areal sorting of stream-bed material, cover for wildlife, and a positive aesthetic experience, may be desirable in many channel projects. Such designs will reduce adverse environmental impacts of stream channel modifications. Analysis of variance for pool-to-pool spacing data suggests that there is no significant difference with respect to channel width between pools that form in natural streams and those in streams affected by a variety of human uses. Short of channelization, which changes the channel width, pools and riffles, within limits, are not particularly sensitive to environmental stress. Experiments in Gum Branch near Charlotte, North Carolina, support the hypothesis that channel form and process evolve in harmony and that manipulation of cross-channel morphology can influence the development of desired channel processes. Planned manipulation of its channel form induced Gum Branch to develop as desired. Morphologic stability consisting of incipient point bars, pools, and riffles was maintained over a period of high magnitude flood events, only to be degraded later by a wave of sediment derived from upstream construction and stream-bank failures. Thus, environmentally desirable channel morphology in urban streams cannot remain stable if changes in the sediment load or storm-water runoff exceed the limits of the stream's ability to make internal adjustments while maintaining morphologic stability.  相似文献   

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