共查询到20条相似文献，搜索用时 31 毫秒
1.
质子激发X射线荧光分析是一种多元素微量分析技术,具有高灵敏度、高空间分辨率和非破坏性等特点,近年来在地球科学诸多领域得到大量应用.本文简介了质子激发X荧光分析技术的基本原理、实验装置及特点,与其他地质学方法进行了比较,并着重介绍该技术在海洋科学领域的应用进展. 相似文献
2.
Stephan A. Klapp Frieder Enzmann Peter Walz Thomas Huthwelker Jürgen Tuckermann J.-Oliver Schwarz Thomas Pape Edward T. Peltzer Rajmund Mokso David Wangner Federica Marone Michael Kersten Gerhard Bohrmann Werner F. Kuhs Marco Stampanoni Peter G. Brewer 《Geo-Marine Letters》2012,32(5-6):555-562
Despite much progress over the past years in fundamental gas hydrate research, frontiers to the unknown are the early beginning and early decomposition of gas hydrates in their natural, submarine environment: gas bubbles meeting ocean water and forming hydrate, and gas starting to escape from the surface of a hydrate grain. In this paper we report on both of these topics, and present three-dimensional microstructure results obtained by synchrotron radiation X-ray cryo-tomographic microscopy (SRXCTM). Hydrates can precipitate when hydrate-forming molecules such as methane exceed solubility, and combine with water within the gas hydrate stability zone. Here we show hydrate formation on surfaces of bubbles from different gas mixtures and seawater, based on underwater robotic in situ experiments in the deep Monterey Canyon, offshore California. Hydrate begins to form from the surrounding water on the bubble surfaces, and subsequently grows inward into the bubble, evidenced by distinct edges. Over time, the bubbles become smaller while gas is being incorporated into newly formed hydrate. In contrast, current understanding has been that hydrate decomposition starts on the outer surface of hydrate aggregates and grains. It is shown that in an early stage of decomposition, newly found tube structures connect well-preserved gas hydrate patches to areas that are dissociating, demonstrating how dissociating areas in a hydrate grain are linked through hydrate that is still intact and will likely decompose at a later stage. Figure
The boundaries of a gas hydrate grain: excepting for the matrix (transparent, not shown), one can see tubular structures, pores from decomposition, and bubbles. 相似文献
3.
SCOPIX: A new X-ray imaging system for core analysis 总被引：3，自引：3，他引：0
SCOPIX is a new digital X-ray imaging system for core analysis that uses an X-ray source coupled to a high-energy brightness
amplifier and a CCD camera. SCOPIX’s numerical files are images in 256 gray levels equal in value to X-ray densities. Possible
data processing approaches include: core logging using grayscale profiles to define the characteristics of sedimentary sequences
and image processing to define and quantify lithologic facies and the geometry of physical and biological structures. Applications
are: recognition of facies and sedimentary processes, study of sedimentary rhythms and geological cycles, and study of biological
and geochemical processes.
Received: 31 March 1998 / Revision received: 25 June 1998 相似文献
4.
SCOPIX is a new digital X-ray imaging system for core analysis that uses an X-ray source coupled to a high-energy brightness amplifier and a CCD camera. SCOPIX’s numerical files are images in 256 gray levels equal in value to X-ray densities. Possible data processing approaches include: core logging using grayscale profiles to define the characteristics of sedimentary sequences and image processing to define and quantify lithologic facies and the geometry of physical and biological structures. Applications are: recognition of facies and sedimentary processes, study of sedimentary rhythms and geological cycles, and study of biological and geochemical processes. 相似文献
5.
Phosphorus Near Edge X-ray Fluorescence Spectroscopy (P-NEXFS) data were collected on phosphorus containing phases including organic and inorganic compounds and minerals. Although phases containing P in the plus five oxidation state P(V) in a tetrahedral PO4 structure have similar primary fluorescence peak positions, the size, shape, and positions of secondary spectral features are diagnostic for different compounds and minerals. In particular, calcium phosphates exhibited a notable post-peak shoulder at 2154.5 eV, while oxidized iron phosphates had a distinctive pre-peak feature at 2148 eV. Polyphosphates have a broad secondary peak located approximately 2 eV higher in energy than a similar feature in phosphate esters and diesters. Compounds containing P(V) in structures other than PO4 tetrahedra such as phosphonates have a primary peak shifted about 1 eV lower than corresponding organo-phosphates. Organo-phosphates with P in the plus three oxidation state P(III) such as phosphines had primary fluorescence peaks shifted still further down in energy (2–3 eV). The substitution of aromatic carbon groups in close proximity to P structures in organic compounds generated both pre- and post-peak features as well as a number of secondary peaks. In addition, X-ray fluorescence mapping of P, Si, Al, Mg, and Na was conducted on a marine sediment sample with sub-micron spatial resolution. Phosphorus was heterogeneously distributed in the sample and not correlated on a broad scale with any other element examined. Much of the P present in the sample was located in small, 0.6–8 μm size, P-rich domains. Several P-rich regions were examined with P-NEXFS using a focused beam with 60 nm resolution and were found to consist of either calcium phosphate or polyphosphate phases. The presence of significant polyphosphate-dominated regions in a marine sediment sample supports the recent observations that such phases can play an important role in marine P cycling. The combination of fluorescence mapping and P-NEXFS data collection on fine particles provides a powerful new tool for environmental phosphorus studies. 相似文献
6.
Twenty-seven samples of suspended sediments collected on Millipore filters from the St. Lawrence estuary were directly analysed for Si, Al, Ca, Mg, Na, K, Fe, Ti, Mn, Ni, Co, Cu, Cr and Zn by X-ray fluorescence using standards prepared from suspended matter collected by continuous flow centrifugation. Calibration curves prepared from the analysis of these standards could be directly used in calculating the weight percent of elements for the unknown samples, if the weight of the total suspended matter on the filters did not exceed 25 mg. 相似文献
7.
X射线荧光光谱法测定海洋沉积物中的41种元素及氧化物 总被引：4，自引：0，他引：4
海洋沉积物样品具有盐分含量高、吸水性强、基体复杂、不同元素浓度差异悬殊等特点,其元素定量分析无论在样品前处理以及分析测试方法都有不少问题。特别是常微量元素很难用同一种方法进行测定,波长色散X射线荧光光谱可以很好的解决这一难题。因此,本文构建了粉末压片制样波长色散X射线荧光光谱法直接测定海洋沉积物样品中41种元素或其氧化物(Na_2O、MgO、Al_2O_3、SiO_2、P、S、Cl、K_2O、CaO、Fe_2O_3、Sc、Ti, V、Cr、Mn、Co、Ni、Cu、Zn、Ga、As、Br、Rb、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Ba、La、Hf、W、Pb、Bi、Ce、Nd、Th、U)的方法。样品在30 t的压力下保压30 s,制备的样片坚固光滑、吸潮性小。针对海洋地质样品的多样性,通过多种校准标准品拟合曲线进行测量,降低了检出限,优化了测量条件。用经验系数、理论α系数与经验系数相结合和康普顿散射线内标法校正元素间的基体效应。对土壤成分标准物质GBW07408和海洋沉积物成分标准物质GBW07315进行精密度考察,大部分元素的方法精密度提高至0.16%~3.87%,绝大多数主次痕量元素的测量精密度(RSD)小于4%,方法检出限为0.8~220μg/g。对渤海湾三个站位沉积物样品41种元素或其氧化物测定,结果表明,测定方法的重复性好,经国家一级标准物质验证,表明方法准确可靠,能满足日常分析要求。该方法对水系沉积物、土壤等陆地地化样品同样适用。 相似文献
8.
A calibration procedure is presented for generating bulk density profiles of intact marine sediment cores using X-ray computed
tomography (CT). Developed using both artificial and natural marine sediment samples, the correlation is strong with an R
2 value of 0.98. Similar experiments with carbonate sediments were also strongly linear, but offset from the terrigenous curve,
illustrating the influence of sediment chemistry on scanner response. Comparison between newly computed densities for both
sediment types with those from individually calibrated cores during our previous CT studies reveals good correspondence between
the data sets.
Received: 22 November 1998 / Revision received: 4 March 1999 相似文献
9.
In an effort to elucidate the mechanism of formation and accretion of ferromanganese nodules, transverse sections of undisturbed botryoid surfaces of nodules from the abyssal central North Pacific were examined by X-ray analyses both by multiple replicate sample transects and mapping. Surface concentrations of Mn and Fe were found of the size and shape of microorganisms. Abundant microorganism-like objects covering the surface and the apparent absence of Si (i.e. no sediment) with the Mn and Fe concentrations suggests microorganisms may be involved either in the selective accretion or removal of these metals. If metal accretion was simply physicochemical, one would expect a more or less even distribution of Mn and Fe on the botryoid surfaces.The replicate X-ray sample transects showed that Mn and Fe have a distribution corresponding to botryoid zonation. Areas of high Mn X-ray intensity were found associated with the cap and equatorial zones of the botryoid. Most of the valley zone of the botryoid show a more or less even Mn distribution and an increase in Fe X-ray intensity. At the base of the botryoid both metals apparently precipitously decrease. 相似文献
10.
《Deep Sea Research Part I: Oceanographic Research Papers》2003,50(6):815-827
Automated ichnofabric analysis was performed on X-ray radiographs from five gravity cores retrieved from Late Quaternary sediments from the SW Portuguese continental slope. The image analysis program DIAna was used to detect and quantify the part of the ichnofabric consisting of pyritized microburrows, presumably Trichichnus and “Mycellia”. Abundance and orientation of the burrows were determined at 5-cm intervals. The results agree with manual counts of burrows in the coarse fraction of the sediment, and they indicate that the abundance of the pyritized burrows depends on enhanced organic carbon content, fine grain size, and low bottom water oxygenation. In contrast, no clear correlation between burrow orientation and environmental conditions was observed. 相似文献
11.
X-射线岩心扫描系统对海洋沉积物成分测定质量的综合评价和校正 总被引：2，自引：0，他引：2
基于采自东海内陆架泥质区的沉积物岩心,利用X-射线岩心扫描系统对其进行高分辨成分扫描,同时利用台式偏振X射线荧光光谱仪对该岩心进行元素测定,通过对比研究评价了X-射线岩心扫描系统元素扫描分析质量。研究表明:（1）X-射线岩心扫描系统对海洋沉积物元素分析质量可以分为四类,Ⅰ类元素分析结果可信度高、可以直接作为含量对待,Ⅱ类具有重要的参考价值,Ⅲ类具有一定参考价值,而Ⅳ类无参考价值。（2）海洋沉积物的X-射线岩心扫描元素分析受到压实作用的影响,其中钙、铁、钾、钛、硅等5种元素压实效应明显,通过压实校正可以有效消除压实作用造成的元素垂向上的系统波动。（3）对钙、铁、钾、钛、硅等5种元素,X-射线岩心扫描强度与传统的XRF元素含量之间具有良好的线性关系,相关系数在0.47~0.87,可以据此进行扫描强度和元素含量的换算。 相似文献
12.
能量色散X射线荧光光谱法测定海洋碎屑沉积物中28种元素 总被引：1，自引：0，他引：1
采用粉末样品压片制样,利用Epsilon3能量色散X射线荧光光谱仪(EDXRF)对我国边缘海碎屑沉积物中28种主量元素和微量元素进行测定。使用33个海洋沉积物、深海沉积物、水系沉积物、三角洲沉积物和岩石标样等国内外标准物质建立标准曲线,采用仪器软件的数学模式校正基体效应和元素间的谱线重叠效应。经国家标准物质检验,分析结果与标样值吻合;元素的检出限为0.02~124.14μg·g-1;精密度(RSD)均小于9%。对我国边缘海碎屑沉积物样品进行分析,其测定值与重量法、电感耦合等离子体光谱法和电感耦合等离子体质谱法的测定值基本一致。鉴于Epsilon3 EDXRF具有体积小、多元素同时快速分析、准确度高和精密度好的优点,可考虑作为船载仪器,在科考现场测定海洋沉积物的元素含量,对于及时指导海上工作、撰写航次报告具有重要作用。 相似文献
13.
Lynn Abramson Sue Wirick Cindy Lee Chris Jacobsen Jay A. Brandes 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(18):1369-1380
Diatoms play a significant role in the global carbon cycle through their role in biogenic silica production and the transport of organic matter to the seafloor. Recent work has shown that silicified diatom frustules contain a significant amount of organic matter, and that the proportion of diatom-bound organic matter increases with depth in the water column and sediments. Here, we investigate the association between organic matter and the mineral phase. We used a combination of scanning transmission X-ray microscopy (STXM) and carbon X-ray absorption near-edge structure (XANES) spectroscopy to characterize the distribution and composition of organic matter in frustules of the diatom Cylindrotheca closterium and a biomimetic silica gel. To our knowledge, this study represents the first successful attempt to simultaneously image and obtain chemical information about the organic matter within a diatom frustule using X-ray spectromicroscopy near the carbon edge. Organic carbon, most likely protein, was distributed throughout the frustules and was not removed by harsh chemical treatment. The physical structure of the frustules appeared to be related to the chemical composition of this organic matter, with aromatic or unsaturated carbon being concentrated in the most intricately patterned regions of the frustule. A similar physical and chemical structure was observed in a biomimetic silica gel precipitated spontaneously with polylysine. These results are consistent with the theory that organic constituents of diatom frustules direct silica precipitation and become incorporated within the silica matrix as it forms. The relationship between organic matter composition and silica morphology, the failure of harsh chemical treatments to remove this organic matter, and the spontaneous nature of the co-precipitation of silica and organic matter indicate some chemical interaction between the siliceous and organic components of diatom frustules. Frustule-bound organic matter should therefore be protected from decomposition in the water column or diagenetic alteration in sediments unless the frustule dissolves. 相似文献
14.
X-ray computed tomography analysis of sediment cores from Eckernförde Bay (western Baltic Sea) indicates that the primary macrostructures and sources of physical property variability are feeding pockets and laminae. Burrowing produces easily discernible macrostructures, yet has a nominal effect overall on sediment property variability. Grain-size distribution is a dominant parameter determining the sediment macrostructure—physical property relationship: the largest variation in sediment properties was associated with sandy sediment and the smallest with muds. However, equally significant is the sorting or spatial distribution of grains within a particular sediment horizon, i.e., whether spatially uniform or patchy. 相似文献
15.
The results of a 57Fe Mössbauer spectroscopic and X-ray diffraction study of four pelagic clay sediments from the Southwestern Pacific Basin collected at increasing distances from New Zealand, on a New Zealand—Rarotonga transect, are presented. These show that, with increasing distance from New Zealand, the Fe3+/Fe2+ ratio of the sediment increases as a result of the increasing contribution of the X-ray amorphous secondary hydrous iron oxides, notably ferrihydrite, due to the longer sedimentation periods and consequent greater degree of oxidation of the sediments. This increase in the Fe3+/Fe2+ ratio is correlated with the change in colour of the sediments from pale yellowish to dusky brown, as well as a number of other sediment parameters. Apart from a slight increase in the relative abundance of montmorillonite with increasing distance from New Zealand, the abundances of the other clay minerals, illite and kaolinite, and of chlorite in the sediments are approximately equal. Quartz and feldspar with minor augite are the dominant detrital minerals. Calcite is present in minor amounts in some of the sediments. 相似文献
16.
During the French-American Mid-Oceanic Undersea Survey (FAMOUS) the French team participating in the mission explored the active A transform fault with the diving saucer CYANA, and discovered a characteristic hydrothermal deposit. The results presented here concern the structural and radiochemical study of three samples: two metalenriched samples and one sample of consolidated calcareous sediment recovered from the area.It is shown that there is a chemical segregation between silica and iron on one hand, and manganese in the other hand, and that on such deposits the layer-by-layer radio-chemical analysis of the uranium series is not applicable.Three different age estimations may be made:In the managanese encrustation, thorium 230 is depleted towards equilibrium with its parent uranium 234, suggesting a maximum age of 45,000 years to the deposit.On the contrary, the outermost layer, 0.1 cm thick, formed essentially with loose sediment stained with oxides, presents an excess of thorium 230. The Σ230Th(excess)/cm2 may be used to calculate a minimum age of 20 years.Such a sediment thickness, in this area, corresponds to a time span of 50 years. 相似文献
17.
X-ray images of sediment core allow recognition of fine-scaled sedimentary structures which traditional epoxy casts or lacquer peels are unable to resolve. The X-ray imaging system SCOPIX has the additional advantage of acquiring high-resolution digital pictures suitable for further analysis by advanced image processing techniques. Because of the frequent presence of both physical and biogenic sedimentary structures in undisturbed sediment cores, two image analysis procedures have been established which simplify the information contained in the images (in term of structures and facies), and allow a quantitative characterization of the observed structures. This form of parametrization of the image structure constitutes an additional source of information for a better interpretation of the physical processes responsible for the generation of the sedimentary structures. 相似文献
18.
19.
基于PXRF的西南印度洋脊硫化物表层沉积物地球化学找矿研究 总被引：3，自引：0，他引：3
海底热液喷发形成的热液羽状流中富含成矿物质,并沉淀在距离热液喷口不等的范围内。对西南印度洋中脊热液喷口附近、距离喷口中等距离、远离喷口的六个表层沉积物样品开展了不同粒度沉积物的便携式XRF（PXRF）分析。结果表明,PXRF可以有效获得的洋中脊钙质沉积物中成矿元素的富集特征。>40目的沉积物样品具有较高的Cu、Zn、Fe、Mn等元素含量,40目以下沉积物中则相对稳定,可能与粗粒沉积物中玄武岩碎屑/玻璃含量较高有关,与镜下鉴定结果一致。以热液喷口为中心,表层沉积物中表现出Cu、Zn、As、Fe、Mn的元素分带,靠近喷口的沉积物中具有较高的成矿元素的含量,并具有较高的Cu/Fe、Zn/Fe比值或者Cu/Mn与Zn/Mn比值。上述结论表明,洋中脊沉积物中成矿元素的含量主要受与喷口的距离的影响,而与粒度的关系不大,洋中脊沉积物地球化学找矿应采用40目以下粒径沉积物作为分析样品。通过PXRF获得的Cu、Zn、As、Fe、Mn等元素含量及其比值特征可以作为海底多金属硫化物沉积物地球化学找矿的指标,该方法满足快速有效识别洋中脊沉积物中地球化学异常的要求。 相似文献
20.
