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1.
《《地质学报》英文版》2002,76(4)
On the occasion of the 80th anniversary of the Geological Society of China, a committee consisting of members of the Editorial Committee was organized to selectthe excellent papers published in the last decade and the result is as follows.* indicates that this paper is published only in the Chinese edition of the journal, and the volume, number, page and year correspond to those of the Chinese edition. 相似文献
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Thi Phuong Quynh Le Nhu Da Le Viet Nga Dao Emma Rochelle-Newall Thi Mai Huong Nguyen Cyril Marchand Thi Thuy Duong Thi Xuan Binh Phung 《Environmental Earth Sciences》2018,77(18):658
Global riverine carbon concentrations and fluxes have been impacted by climate and human-induced changes for many decades. This paper aims to reconstruct the longterm carbon concentrations and carbon fluxes of the Red River, a system under the coupled pressures of environmental change and human activity. Based on (1) the relationships between particulate and dissolved organic carbon (POC, DOC) or dissolved inorganic carbon (DIC), and suspended sediments (TSS) or river water discharge and on (2) the available detailed historical records of river discharge and TSS concentration, the variations of the Red River carbon concentration and flux were estimated for the period 1960–2015. The results show that total carbon flux of the Red River averaged 2555?±?639 kton C year?1. DIC fluxes dominated total carbon fluxes, representing 64% of total, reflecting a strong weathering process from carbonate rocks in the upstream basin. Total carbon fluxes significantly decreased from 2816 kton C year?1 during the 1960s to 1372 kton C year?1 during the 2010s and showed clear seasonal and spatial variations. Organic carbon flux decreased in both quantity and proportion of the total carbon flux from 40.9% in 1960s to 14.9% in 2010s, reflecting the important impact of dam impoundment. DIC flux was also reduced over this period potentially as a consequence of carbonate precipitation in the irrigated, agricultural land and the reduction of the Red River water discharge toward the sea. These decreases in TSS and carbon fluxes are probably partially responsible for different negatives impacts observed in the coastal zone. 相似文献
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1Introduction Tracemetalsarereleasedtotheatmosphereduring combustionoffossilfuelsandwood,aswellasemis sionsfromavarietyofprocessesactingoncrustalmin erals,includingvolcanism,erosionandsurfaceweath ering.Onaglobalscale,resuspendedsurfacedusts havemadeagreatcontributiontothetotalnaturale missionoftracemetalstotheatmosphere,withCr,Mn andVaccountingfor>50%andCu,Mo,Ni,Pb,Sb andZnaccountingfor>20%,whilevolcanicactivity probablygeneratedasmuchas20%atmosphericCd,Hg,As,Cr,Cu,Ni,PbandSb(Pacyna,19… 相似文献
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Karl Picard 《International Journal of Earth Sciences》1952,40(1):51-55
Zusammenfassung Bei Eiskeilen mit Sandfüllung in einem sandigen Sediment sind die Erscheinungsbilder von der Häufigkeit des Aufspringens des Bodens und der Sandführung der Schmelzwässer abhängig. Die ursprüngliche Form bei solchen Eiskeilen ist nur in den Teilen erhalten, wo die Schichten des Nebengesteins ungestört an den Eiskeil herantreten. Materialunterschiede des Nebengesteins und der Füllung der Eiskeile müssen bei Rückschlüssen aus der Breite der Eiskeile verschiedener Gegenden auf klimatische Gegebenheiten berücksichtigt werden. 相似文献
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本书为美国 MINOBRAS 1979年发表的科研成果。书中介绍了变质作用的机理、变质岩的种类、有铀矿床产出的前寒武纪岩石的年龄和分布地区、变质岩中的铀含量和矿床类型等。本书还叙述了全世界已知变质型铀矿床的地质情况、控矿因素、成因、储量和远景地区。 相似文献
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Fe(II)–Ca(II), Fe(II)–Na(I), and Fe(II)–Ca(II)–Na(I) exchange experiments on montmorillonite were performed in chloride background. These experiments show the possible sorption of Fe2+ and FeCl+ ion pairs in exchange site positions, a result confirmed with 77 K 57Fe Mössbauer experiments. The sorption data were modeled and the cation exchange selectivity for Fe(II) were found to be nearly equal to that of Ca(II). Vanselow selectivity coefficients, for Na–Fe2+ and Na–FeCl+ reactions, were found to be equal to 0.4 (0.5 for Ca2+) and 2.3 (2.5 for CaCl+) respectively. High affinity of montmorillonite for chloride ion pairs seems to be a common mechanism as first stated by Sposito et al., (Soil Sci. Soc. Am. J. 47, 51–56, 1983a), and should have implications e.g., on the chemistry of suspended particles in seawater. Exchange selectivity coefficients derived from this study and others were used to model experimental data on river water and seawater equilibrated particles. The agreement between simulations and experimental data is very good. The simulation shows the predominance of monovalent ion (Na+ and chloride ion pairs) sorption on clay particles in seawater. This sorption of monovalent ions leads to the dispersion of particles in seawater and to the extension of a plume of particles spreading away from river deltas, such as that of the River Amazon. 相似文献
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Stephen Mackwell Misha Bystricky Caroline Sproni 《Physics and Chemistry of Minerals》2005,32(5-6):418-425
We have performed a series of interdiffusion experiments on magnesiowüstite samples at room pressure, temperatures from 1,320° to 1,400°C, and oxygen fugacities from 10?1.0 Pa to 10?4.3 Pa, using mixed CO/CO2 or H2/CO2 gases. The interdiffusion couples were composed of a single-crystal of MgO lightly pressed against a single-crystal of (Mg1-x Fe x )1-δO with 0.07<x<0.27. The interdiffusion coefficient was calculated using the Boltzmann–Matano analysis as a function of iron content, oxygen fugacity, temperature, and water fugacity. For the entire range of conditions tested and for compositions with 0.01<x<0.27, the interdiffusion coefficient varies as $$\tilde D\, =\,2.9\times10^{ - 6}\,f_{{\text{O}}_2 }^{0.19}\,x^{0.73}\,{\text{e}}^{ - (209,000\, -\,96,000\,x)/RT}\,\,{\text{m}}^{\text{2}} {\text{s}}^{ -1} $$ These dependencies on oxygen fugacity and composition are reasonably consistent with interdiffusion mediated by unassociated cation vacancies. For the limited range of water activity that could be investigated using mixed gases at room pressure, no effect of water on interdiffusion could be observed. The dependence of the interdiffusion coefficient on iron content decreased with increasing iron concentration at constant oxygen fugacity and temperature. There is a close agreement between our activation energy for interdiffusion extrapolated to zero iron content (x=0) and that of previous researchers who used electrical conductivity experiments to determine vacancy diffusivities in lightly doped MgO. 相似文献
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Motor vehicles historically have been dangerous locations to shelter in during tornado events. Throughout the twentieth century, motor vehicle design has become safer while tornado forecasting has become better understood. Despite such advances, tornado fatalities in motor vehicles still occur today, and some events periodically result in high numbers of deaths (e.g., ten motor vehicle occupants were killed by a single tornado in Garland, Texas, in 2015). We seek to examine all US tornado-induced motor vehicle fatalities documented between 1991 and 2015. Our findings indicate that motor vehicle fatalities have not significantly changed during this study period. We attribute annual fatality totals to persons lacking awareness of impending dangers coupled with numbers of significant tornado events for a given year. We find most fatalities result when vehicles are lofted or passengers are ejected, and this most typically occurs at the EF3–EF5 intensity thresholds. Fatalities that occur at weaker tornado winds (EF0–EF2) are most often attributed to collapsing debris (mostly trees) on vehicles. Spatially, motor vehicle fatalities are greatest in the Deep South and southern Great Plains regions where overall tornado and nighttime tornado frequencies are greatest. Some of the largest motor vehicle fatality events have resulted from tornadoes not being distinctly visible to motorists; such events have been characterized by tornadoes occurring at night or by tornadoes not appearing as “classic funnels.” 相似文献
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《中国地球化学学报》2006,(Z1)
The biogeochemical migration of iodine in soil and its effect factors were studied by the isotope tracer (125I) and experiments of leaching and absorption by Chinese cabbage to iodine under simulated condition. The results show that the quantities of tran… 相似文献
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Analysis of eight outcrops from Rarău Massif (Eastern Carpathians, Romania) revealed a rich assemblage of encrusting organisms mostly of problematic biological affiliation within platform-margin facies – Crescentiella morronensis, Radiomura cautica, Koskinobullina socialis, Pseudorothpletzella schmidi, Lithocodium aggregatum and bacinellid structures, encrusting calcified sponges (Calcistella jachenhausenensis, Neuropora lusitanica) and foraminifera (Coscinophragma cribrosa). Orbitolinids, calcareous green algae and rudists assign an early Aptian age (Bedoulian) for the studied limestones. In terms of species variety, abundance and structural microfabrics the studied microencruster association show similarity with the Upper Jurassic communities from reef and peri-reefal sedimentary settings. Comparisons with such assemblages are emphasized here. The presence of the sporolithacean and peyssonneliacean red algae (Sporolithon rude and Polystrata alba) contributes also to the construction of superimposed crusts. Even if the known stratigraphic range of the microencrusters is not strictly limited to the late Jurassic, reports of comparable associations in Urgonian-type facies is poorly documented. Therefore, it exemplifies the resistance and flourishing events of many encrusters throughout the Mesozoic. 相似文献
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The Kamchatka peninsula, located in the far east of Russia, is a geologically active margin where the Pacific plate subducts beneath the North American and Eurasia plates. This area is characterised by frequent and strong seismic activity (magnitudes up to 8.5) and epicentres are generally distributed offshore along the eastern coast of the peninsula. For many years, hydrogeochemicals have been collected with a mean sampling frequency of three days in the form of the flow rate and the most common ions and gases in the groundwater of three deep wells in the southern area of the Kamchatka peninsula, where the capital city Petropavlovsk is located. Beginning in 1988, five earthquakes with M > 6.5 occurred in this area. These earthquakes were powerful enough to be considered as potential precursor sources in the sense that the stresses and strains building up before them might be expected to cause precursory activity. In order to reveal any possible precursors of these earthquakes, we analysed the hydrogeochemical data collected. We considered any signal having an amplitude three times the standard deviation to be an irregularity and we defined as an anomaly the existence of an irregularity occurring simultaneously in more than one parameter at each well. Then, on the basis of the worldwide past results and the time recurrence of the quoted earthquakes, we chose 158 days as the maximum temporal window between a possible anomaly and the subsequent earthquake. We identified some premonitory anomalies in hydrogeochemical parameters at different wells. On the basis of these results some earthquake forecasting criteria in southern Kamchatka may be tentatively formulated 相似文献
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Hydrogen Isotopes of Glassy and Phyllosilicate Spherules in Al Rais (CR) and Orgueil (CI) Chondrites
Michael E.ZOLENSKY 《《地质学报》英文版》2004,78(5)
The hydroxyl in phyllosilicate minerals is the most common occurrence of water in primitive meteorites. Direct hydrogen isotopic analysis of this water component using an ion microprobe has been made in some glassy or phyllosilicate spherules from the Al Rais (CR) and Orgueil (CI) chondrites. The spherules from Al Rais show large deuterium excesses (δD = +200 -+800‰) relative to terrestrial standards, whereas deuterium-enrichments in the spherules from Orgueil are much smaller (δD = +40 - +130‰). The phyllosilicate spherules are products of 相似文献
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Fritz A. Pfaffl 《International Journal of Earth Sciences》2009,98(3):707-714
Ernst Weinschenk was an excellent teacher at the High School of Technology from 1897 till his death 1921, and at the university
in Munich from 1900. His studies of the mineralogy of meteorites and the contact-metamorphic mineralization in the eastern
and western Alps and southern Tyrol made him widely known early-on. He successfully determined many new minerals with the
aid of the polarizing microscope and the use of mineral and thin rock sections. He attributed the genesis of the sulfidic
ore deposit Silberberg at Bodenmais (northern Bavarian Forest) and the graphite deposits near Passau (Lower Bavaria) to the
exhalative output of sulphur and carbon during the granite orogenesis (Weinschenk 1914). 相似文献
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The Silius vein system, located in SE Sardinia (Italy) is analogous to other late- to post-Hercynian mineral systems of this type in Europe. The Silius system consists of two main veins, characterized by several generations of fluorite, calcite and quartz, with initial ribbon-like geometries, followed by breccias and cockade-like textures. In this study, aimed at investigating the REE concentrations in the Silius vein system, a REE average of ~ 800 ppm (locally ΣREE > 1500 ppm) has been observed in the carbonate gangue of the fluorite orebody. These amounts are related to the presence of the REE-bearing minerals synchysite-(Ce) and xenotime-(Y). The chemical composition of synchysite-(Ce) has been obtained by wavelength dispersive spectrometry (WDS). The average synchysite-(Ce) formula, built on the basis of (CO3)2F and 5 negative charges, is Ca1.07(La0.19,Ce0.36,Pr0.04,Nd0.15,Sm0.03,Gd0.03,Y0.13)(CO3)2F. From their geochemical characteristics, and their textural relationships with other gangue phases, it is likely that synchysite-(Ce) and xenotime-(Y) formed at the same P-T-X conditions as the other minerals of the Silius fluorite mineralization. Synchysite-(Ce) and xenotime-(Y) at Silius could be related to a local circulation phenomenon, where the REE are derived from a REE-bearing source rock in the basement of southeastern Sardinia, which has been leached by the same fluids precipitating the fluorite/calcite mineralization. REE concentrations contained in the carbonate gangue of still unexploited parts of the Silius vein deposit, as well as in dumps and tailings accumulated during past fluorite processing, could possibly represent a sub-economic by-product of the fluorite exploitation. 相似文献
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YANG Yuncheng SHEN Zhaoli WEN Dongguang HOU Guangcai SHE Hongquan ZHAO Zhenhong WANG Dong LI Jingwen 《《地质学报》英文版》2010,84(2):432-440
<正>The Ordos Cretaceous Groundwater Basin,located in an arid-semiarid area in northwestern China,is a large-style groundwater basin.SO_4~(2-) is one of the major harmful components in groundwater.Dissolved SO_4~(2-) concentrations,andδ~(34)S-SO_4~(2-) andδ~(18)O-SO_4~(2-) in groundwater from 14 boreholes and in gypsum from aquifer were analyzed.Results show that SO_4~(2-) in shallow groundwaters originates from precipitation,sulfide oxidation,and dissolution of stratum sulphate,with a big range ofδ~(34)S values,from-10.7‰to 9.2‰,and addition of SO_4~(2-) in deep groundwater results from dissolution of stratum sulphate,with biggerδ~(34)S values,from 7.8‰to 18.5‰,compared with those in shallow groundwater.This research also indicates that three types of sulphate are present in the strata,and characterized by highδ~(34)S values and highδ~(18)O values-style,highδ~(34)S values and middleδ~(18)O valuesstyle, middleδ~(34)S values and lowδ~(18)O values-style,respectively.Theδ~(34)S-SO_4~(2-) andδ~(18)O-SO_4~(2-) in groundwater have a good perspective for application in distinguishing different groundwater systems and determining groundwater circulation and evolution in this area. 相似文献
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J. S. Lin M. C. Payne V. Heine J. D. C. McConnell 《Physics and Chemistry of Minerals》1994,21(3):150-155
Ab initio total energy calculations based on a new optimized oxygen psuedopotential have been used to study the structures
and relative energies of α-quartz, a partly (OH)4 substituted version of the α-quartz structure, and interstitial water molecules in α-quartz. Hydrogen bonds formed from two hydroxyl groups of the (OH)4 defects in the substituted α-quartz structure promote a stable structure for the defect α-quartz at low temperature. Comparable ab initio calculation of the energy of the interstitial water molecule in the quartz
structure indicates that, energetically, the (OH)4 defect is likely to be strongly favoured as a mode for the incorporation of water. Ab initio stress calculations confirm
that the (OH)4 defect in quartz has a large associated stress field which is likely to lead to segregation of these defects on supersaturation
in wet quartz. The calculations indicate that segregation should occur in the plane (10
0) of the α-quartz structure. 相似文献