Determination of Gold, Silver and Platinum-Group Elements in Geochemical Reference Materials by Direct Atomic Emission Spectral Analysis Using a Multichannel Analyser Recording Device     

Svetlana B. Zayakina  Gennady N. Anoshin 《Geostandards and Geoanalytical Research》2001,25(1):57-66

A procedure for the analysis of geochemical samples has been developed based on direct atomic-emission spectrometry for the determination of silver, gold and the platinum-group elements. Instrumentation comprised a DC arc emission two-jet plasmatron coupled to a diffraction spectrograph and multichannel analyser for recording emission spectra. Spectrum analysis used a comprehensive library of spectral lines for practically all elements excited using this emission source. The software programme for the automatic registration of spectra and subsequent data processing are described and results presented for a number of geochemical reference materials.  相似文献   

Observations on New Approaches for the Determination of Platinum-Group Elements, Gold and Silver in Different Geochemical Samples from Siberia and the Far East   总被引：1，自引：0，他引：1  

Valentina G. Tsimbalist  Gennady N. Anoshin  Valentin N. Mitkin  Ljudmila I. Razvorotneva  Nadezhda P. Golovanova 《Geostandards and Geoanalytical Research》2000,24(2):171-182

Some recent experiments on the determination of Au and the platinum-group elements (PGE) in geochemical samples are reviewed. Emphasis is given to the determination of ultra-low levels of PGE concentrations in resistant matrices, including chromites, molybdenites and ultrabasic ores. The problems and features of PGE determination in samples of various chemical composition are considered. For each sample type studied, a series of sample preparation techniques are proposed. These techniques included acid digestion, fusion with sodium peroxide, cold sintering with an oxidizing mixture of Na₂O₂+ Na₂CO₃ and also oxidizing fluorination with bromine trifluoride. A new approach for preparing geochemical material prior to digestion, based on mechano-chemical activation with simultaneous hyperfine grinding, is proposed and studied. The instrumental determination of PGE contents was carried out directly by AAS from extracted organic phases. It was found that a combination of digestion processes was required to achieve geochemical background levels of Au and PGE concentrations with the following detection limits: Pd, Rh - 1 ng g⁻¹, Pt, Ru - 10 ng g⁻¹, Au - 0.2 ng g⁻¹, Ag - 0.1 ng g^−1. The uncertainty in PGE and Au determination in geochemical samples is dependent on metal concentration, and also on their distribution in samples. The total analytical uncertainty of the proposed method is between 15-30%.  相似文献   

Faunal communities at sites of gas- and oil-bearing fluids in Lake Baikal     

Tamara I. Zemskaya  Tatiana Y. Sitnikova  Sergei I. Kiyashko  Gennady V. Kalmychkov  Tatiana V. Pogodaeva  Irina V. Mekhanikova  Tatiana V. Naumova  Olga V. Shubenkova  Svetlana M. Chernitsina  Oleg V. Kotsar  Evgeny S. Chernyaev  Oleg M. Khlystov 《Geo-Marine Letters》2012,32(5-6):437-451

Macro- and meiofaunal communities were examined at four geomorphologically distinct sites with different gas- and oil-bearing fluid characteristics in the northern, central and southern basins of Lake Baikal. All sites had elevated concentrations of bicarbonate, nitrate, sulphate and chloride ions in pore fluids, with highest values at the Frolikha vent. Elevated levels of iron ions were found in pore waters of the St. Petersburg methane seep and the Gorevoy Utes oil seep. The chemical composition of pore waters at the Malenky mud volcano was similar to that reported in earlier work. Consistent with published data, the Frolikha vent (northern basin) and the St. Petersburg methane seep (central basin) were characterised by methane of mixed genesis (thermogenic + biogenic), whereas the methane source was mainly thermogenic at the Gorevoy Utes oil seep (central basin) and biogenic at the Malenky mud volcano (southern basin). In contrast to marine seep ecosystems, the macrofauna was dominated only by amphipods, giant planarians and oligochaetes, whereas bivalves were absent; the meiofauna was similar to its marine counterpart, being dominated by nematodes, cyclops, harpacticoids and ostracods. A statistically significant positive relationship was revealed between faunal abundance and the availability of bacterial mats on seep sediments. Moreover, ANOVA tests showed significant increases in both meiozoobenthic and macrozoobenthic densities at “hot spot” vent/seep sites relative to discharge-free reference sites. The isotopic composition of carbon and nitrogen at various trophic levels of these benthic vent/seep communities was found to differ markedly from that reported by earlier studies for the pelagic and other benthic food webs in Lake Baikal. As in marine seeps, the macrofauna had variable isotopic signatures. Light δ¹³C and δ¹⁵N values suggest the utilization of chemosynthetically fixed and/or methane-derived organic matter. By contrast, the heavy δ¹³C signatures of some mobile amphipods likely reflect consumption of photosynthetically derived carbon. These findings would at least partly explain why Lake Baikal is a notable outlier in global temperature–biodiversity patterns, exhibiting the highest biodiversity of any lake worldwide but at an extremely cold average temperature.  相似文献   

Comparison of retrospective analyses of the global ocean heat content     

Gennady A. Chepurin  James A. Carton 《Dynamics of Atmospheres and Oceans》1999,29(2-4)

In this study, we compare seven retrospective analyses of basin- to global-scale upper ocean temperature. The analyses span a minimum of 10 years during the 50-year period since World War II. Three of the analyses (WOA-94, WHITE, BMRC) are based on objective analysis and thus, do not rely on a numerical forecast model. The remaining four (NCEP, WAJSOWICZ, ROSATI, SODA) are based on data assimilation in which the numerical forecast is provided by some form of the Geophysical Fluid Dynamics Laboratory Modular Ocean Model driven by historical winds. The comparison presented here is limited to heat content in the upper 250 m, information that is available for all analyses. The results are presented in three frequency bands: seasonal, interannual (periods of 1–5 years), and decadal (periods of 5–25 years). At seasonal frequencies, all of the analyses are quite similar. Otherwise, the differences among analyses are limited to the regions of the western boundary currents, and some regions in the Southern Hemisphere. At interannual frequencies, significant differences appear between the objective analyses and the data assimilation analyses. Along the equator in the Pacific, where variability is dominated by El Niño, the objective analyses have somewhat noisier fields, as well as reduced variance prior to 1980 due to lack of observations. Still, the correlation among analyses generally exceeds 80% in this region. Along the equator in the Atlantic, the correlation is lower (30–60%) although inspection of the time series shows that the same biennial progression of warm and cool events appears in all analyses since 1980. In the midlatitude Pacific agreement among objective analyses and data assimilation analyses is good. The analysis of Rosati et al. [Rosati, A., Gudgel, R., Miyakoda, K., 1995. Decadal analysis produced from an ocean assimilation system. Mon. Weather Rev., 123, 2, 206.] differs somewhat from the others apparently because in this analysis, the forecast model is weighted more heavily relative to the observations. The analysis of Levitus et al. [Levitus, S., Boyer, T.P., Antonov, J., 1994. Interannual variability of upper ocean thermal structure. World Ocean Atlas, 1994, Vol. 5. Natl. Env. Satell. Data and Int. Serv., Natl. Oceanic and Atmos. Admin. Atlas series, Washington, DC, 176 pp.] has a much different spatial distribution of variability in the interannual band than the others. Partly, this results from the yearly time-averaging of this analysis. Three of the monthly analyses extend over 20 years and thus are useful for examining decadal variations. Comparison of these analyses shows in common a slow progression of warm water westward and then eastward along the equator in the tropical Pacific that is linked to the decadal fluctuations of El Niño.  相似文献   

Three‐dimensional modeling of coastal boulders using multi‐view image measurements          下载免费PDF全文

Gennady A. Gienko  James P. Terry 《地球表面变化过程与地形》2014,39(7):853-864

Coarse clastic sediments (boulders) on coastlines have seen a groundswell in geomorphic research interest over recent years, associated in part with the potential of boulder evidence for interpreting characteristics of high‐energy wave processes. Yet, the fundamental property of boulder volume is normally difficult to measure accurately owing to complex clast morphology and irregular surface texture. To tackle this problem, this paper concentrates on creating precise, measurable and textured three‐dimensional (3D) models of coastal boulders without physical contact with the object, based on multi‐view image measurement techniques. This method has several advantages over traditional measurements that are inaccurate or alternative solutions using costly techniques such as terrestrial laser scanning. Our methods propose the use of low‐cost equipment (digital cameras) that can be used in various coastal environments to easily acquire numerous images of the object of interest. Initial results can be rapidly assessed in the field for immediate quality control. Resulting 3D models, built from overlapping multi‐view digital photographs, allow the reconstruction of realistic‐looking and textured boulder surfaces. A particular interest in this task is the family of algorithms known as structure from motion (SFM). The work presents analysis of SFM techniques by examining 3D models of boulders observed at a coastal field site on Lu Dao Island in south‐eastern Taiwan. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

The Sychevka IIIAB iron meteorite: A new find from Russia     

Alexander N. Krot  Nina I. Zaslavskay  Michail I. Petaev  Natalya N. Kononkova  Gennady M. Kolesov  Lydia D. Barsukova 《Meteoritics & planetary science》1992,27(4):465-466

Abstract— Sychevka is a relatively unweathered 65-kg iron meteorite that was found in Russia in 1988. The microstructure, mineralogy and bulk composition of Sychevka as revealed by optical microscopy, electron microprobe and instrumental neutron activation analysis indicate that this meteorite is a group-IIIAB medium octahedrite. Sychevka consists of (in vol%): kamacite (82.5), plessite (16), schreibersite (1.5), and rare grains of chromite and troilite.  相似文献   

Intelligent Visualisation and Information Presentation for Civil Crisis Management   总被引：1，自引：0，他引：1  

Natalia Andrienko  Gennady Andrienko 《Transactions in GIS》2007,11(6):889-909

This paper describes an ongoing research work on developing methods for effective visualisation support for situation analysis, decision making, and communication in the course of disaster management. The major goals are to reduce the information load of the analyst, decision maker, or information recipient without omission of anything important and to ensure quick and accurate comprehending of the information. The work embraces the issues of selection of the relevant information and defining the appropriate level of detail, data preparation (aggregation and other transformations), and selection of the appropriate methods for visual representation depending on the user's tasks or communication goals, recipient's profile, and the target presentation medium. A practical outcome from the research will be a knowledge base that can be used to support analysis, decision making, and information communication in emergency situations. A great part of the knowledge, specifically, knowledge on data transformation and representation, is generic and can be used for different applications.  相似文献