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The δ^(18)O variation of a stalagmite from Qixing Cave,Guizhou Province and indi-cated climate change during the Holocene

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Chinese Science Bulletin 2001年第22期46卷 1904-1908页

作者： CAI Yanjun, ZHANG Meiliang, PENG Zicheng, LIN Yushi, AN Zhisheng, ZHANG Zhaofeng & CAO Yunningstate Key laboratory of Loess and Quaternary geology, Institute of Earth Environment, Chinese Academy of Sciences, xi’an 710054,{3. Karst dynamics laboratory, Ministry of Land and Resources, Guilin 541003.{3. department of Earth and Space Science, university of Science & Technology of{3., Hefei 23.023.{3. state Key laboratory of Loess and Quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China Karst dynamics laboratory Ministry of Land and Resources Guilin China department of Earth and Space Science University of Science & Technology of China Hefei China

A stalagmite from Qixing Cave, Guizhou Province was dated with the TIMS U-series method and its oxygen isotope composition was analyzed. On the basis of the ages and the variations of the δ18O of the stalagmite, the climate change of the last 7.7 ka has been reconstructed in this area: 7.7-5.8 ka, summer monsoon maximum period; 5.8-3.8 ka summer monsoon weakening period; 3.8-0.15 ka, weakened summer monsoon and high amplitude climate fluctuations period. We put forward that the increasing trend of δ18O of the stalagmite reflected not only the weakening of the summer monsoon, which was caused by the decreasing of solar radiation in the Northern Hemisphere, but also the possibly decreasing contribution of the southwest monsoon to the rainfall of this area. These results are consistent with the output of the numerical climate-model modeling. The high amplitude fluctuation of the δ18O may imply the quick shift of the contributions of different moisture sources to the precipitation in this area.

关键词： stalagmite Holocene southwest monsoon.

Micro-and Nano-structure Characterization of Isotropic Pyrocarbon Obtained via Chemical Vapor Deposition in Hot Wall Reactor

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Journal of Materials Science & Technology 2010年第12期26卷 1133-1138页

作者： Kezhi Li,Dongsheng Zhang,Lingjun Guo and Hejun Li state Key laboratory of Solidification Processing,northwestern Polytechnical {3.,xi an 710072,china [a] state Key laboratory of Solidification Processing northwestern Polytechnical university xi'an 710072 china

The hot wall reactor was used to deposit isotropic pyrocarbon. The density of the product was measured by Archimedes method. The fracture morphology and texture of the product were investigated by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Raman spectroscopy was also applied to characterizing the structure of the product. The results show that the density of the product is about 1.3. g/cm^3. The pyrocarbon consists of granular particles with the size of about 1.5 μm under SEM images. Under TEM images, the pyrocarbon is composed of irregular grains and onion-like particles are also detected. The orientation angle （180 deg.） of pyrocarbon reveals its isotropic character. The ID/IG ratio in Raman spectrum is about 1.2, indicating the isotropic feature of the product qualitatively.

关键词： Isotropic pyrocarbon Chemical vapor deposition Structure characterization Onion-like pyrocarbon

Nitrogen isotopic composition of plant-soil in the Loess Plateau and its responding to environmental change

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Chinese Science Bulletin 2009年第2期54卷 272-279页

作者： LIU WeiGuo1,2 & WANG Zheng1,3.1 state Key laboratory of Loess and Quaternary geology, Institute of Earth Environment, Chinese Academy of Sciences, xi’an 710075,{3. 2 xi’an Jiaotong university, School of Human Settlement and Civil Engineering, xi’an 710049,{3. 3.Graduate university of Chinese Academy of Sciences, Beijing 100049,{3. Chinese Acad Sci Inst Earth Environm State Key Lab Loess and Quaternary Geol Xian 710075 Peoples R China.

The nitrogen isotope of soil is of emerging significance as an indicator of climatic change and biogeochemical cycle of nitrogen in nature systems. In this paper, the nitrogen content and isotopic composition of modern ecosystems from arid and semiarid Loess Plateau in northwestern china, including plant roots and surface soil, were determined to investigate trends in δ15N variation of plant roots and soil along a precipitation and temperature gradient in northwestern china under the East Asian Monsoon climate condition. The δ15N values of surface soil from the study area vary from ?1.2‰ to 5.8‰, but from -5.1‰ to 1.9‰ in the plant roots. Our results indicate that (1) although the isotopic compositions of both plant roots and surface soil change with a similar trend along the climate gradient, the apparent nitrogen difference between plant roots and soil existed, with -δ15N values ranging from 0.3. to 7.2‰ with average of 4.1‰; and (2) mean annual precipitation (MAP) is the dominant factor for isotopic composition of plant-soil nitrogen in the Loess Plateau, and the δ15N values are less correlated with MAT; we suggest that nitrogen isotopic composition of soil is a potential tracer for environmental changes.

关键词：氮同位素物理性质化学性质环境论

Stability of stratified flow and slugging in horizontal gas-liquid flow

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Progress in Natural Science:Materials International 2005年第11期15卷 1026-1034页

作者： GU Hanyang and GUO Liejin (state Key laboratory of Multiphase Flow in Power Engineering, xi’an Jiaotong university, xi’an 710049,{3.) state Key laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong University Xi''an 710049 China

A transient one-dimensional two-fluid model is proposed to investigate numerically the interfacial instability and the onset of slugging for liquid-gas flow in a horizontal duct. In the present model, the effects of surface tension and transverse variations in dynamic pressure are taken into account. The evolution of interfacial disturbances is displayed and compared with the linear viscous Kelvin-Helmholtz stability analyses. It shows that interfacial wave is more instable due to the non-linear effect. The model predicts well the stability limit of stratified flow in comparison with the experimental data, and also automatically tracks the onset of slugging. The results show that the initiation of hydrodynamic slugging is related to local interfacial instability. Based on the cycle of slugging, a model for slug frequency is presented, which predicts the trends of slug frequencies with gas/liquid flow rate well in comparison with the available data. The effects of physical properties on slugging have been examined. It is found that with the increase in the gas viscosity and liquid density the slugging would be inhibited, whereas, with the increase in liquid viscosity and gas density, the slugging can be promoted.

关键词： two-fluid model Kelvin-Helmholtz stability interfacial instability onset of slugging gas-liquid stratified flow.

The gravitational gradient tensor’s invariants and the related boundary conditions

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Science china Earth Sciences 2010年第5期53卷 781-790页

作者： YU JinHai1,2,3.& ZHAO DongMing4 1 College of Earth Science, Graduate university of Chinese Academy of Sciences, Beijing 100049, china 2 Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 43.077, china 3.{3. Key laboratory of Astronautic dynamics, xi’an 710043. china 4 Zhengzhou Institute of Surveying and Mapping, Zhengzhou 450052, china 1. College of Earth Science Graduate University of Chinese Academy of Sciences Beijing 100049 China2. Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China3. State Key Laboratory of Astronautic Dynamics Xi’an 710043 China4. Zhengzhou Institute of Surveying and Mapping Zhengzhou 450052 China

Here we report new approaches of recovering the Earth gravitational field from GOCE (Gravity field and steady-state Ocean Circulation Explorer) gradiometric data with the help of the gradient tensor’s invariants. Our results only depend on GOCE satellite’s position and gradiometry, in other words, they are completely independent of the satellite attitude. First, starting from the invariants, linearization models are established, which can be referred as the general boundary conditions on the satellite’s orbit. Then, the spherical approximation expressions for the models are derived, and the corresponding solving methods for them are discussed. Furthermore, considering effects of J2-term, the spherical approximation models are improved so that the accuracies of the boundary conditions can be theoretically raised to O ( J 2/2 T), which is approximately equivalent to O(T2). Finally, some arithmetic examples are constructed from EGM96 model based on the derived theories, and the computational results illustrate that the spherical models have accuracies of 10-7 and the order recovering the gravitational field can reach up to 200, and the models with regard to effect of J2-term have accuracies of 10-8 and the order can reach up to 280.

关键词： the Earth’s gravitational field gravitational gravidiometry tensor’s invariant

Exsolution of ilmenite and Cr-Ti magnetite from olivine of garnet-wehrlite

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Science china Earth Sciences 2005年第9期48卷 1368-1376页

作者： LIU xiangwen1,2, JIN Zhenmin1,3. QU Jing2 & WANG Lu2 1. state Key laboratory of Geological Processes and Mineral Resources, china {3. of Geosciences, Wuhan 43.074, china 2. Graduate School of china {3. of Geosciences, Wuhan 43.074, china 3. Faculty of Earth Sciences, china {3. of Geosciences, Wuhan 43.074, china 1. state Key laboratory of Geological Processes and Mineral Resources China University of Geosciences 430074 Wuhan China 2. Graduate School of china university of Geosciences 430074 Wuhan China 3. Faculty of Earth Sciences China University of Geosciences 430074 Wuhan China

Exsolution of rod-like ilmenite (Ilm) and Cr-Ti magnetite (Mt) have been found in olivine of garnet-wehrlite from the core of Chinese continental Sciences Drilling (CCSD). Their composition, morphology, crystal structure and their topotaxies with host olivine have been studied in detail by the transmission electron microscopy (TEM) and electron probe microanaly- sis (EPMA) technique. It shows that rod-like Ilm exsolution reported in this paper has similar characteristic with that of Alpe Arami olivine, while Cr-Ti magnetite exsolution mentioned in this paper has large discrepancy with chromite exsolution in Alpe Arami olivine. These observations suggest that both of the exsolutions found in this paper should be solid solution phases in β-olivine at their first period, then experiencing decomposition of solid solution and therefore forming Ilm and Cr-Ti magnetite exsolution with the pressure decreasing. So, this garnet-wehrlite perhaps had been ever located in mantle transition zone with a minimum depth of 3.0 km.

关键词： garnet-wehrlite, ilmenite, magnetite, exsolution, CCSD.

On the Phylum Vetulicolia

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Science Bulletin 2005年第20期 88-100页

作者： SHU Degan Early Life Institute and Key laboratory of continental dynamics,{3., xi’an 710069, School of Earth Sciences and Re- sources, china university of Geosciences, Beijing 100083. china

The origins and radiations of metazoans, bilat- erians, deuterostomes and vertebrates have been recognized as the four most important milestone events in animal his- tory and, conversely four of the toughest and puzzling ques- tions in evolutionary biology. Among them, the first two oc- curred in the deep time of the Precambrian and have left little information in the fossil records. Fortunately, intensive investigation into the Early Cambrian Chengjiang faunas in the past two decades have revealed numerous significant data on the main episode of the Cambrian Explosion, par- ticularly information on the various earliest-known deu- terostomes, leading to a much better understanding of the last two events. The “first fish” Haikouichthys and Myllo- kunmingia have been proved the oldest-known vertebrates, and to be among the most primitive ones, representing a key transitional group from acraniates to craniates. Indeed, “Pa- leontological work of Shu and collaborators is revising our understanding of the early evolution of chordates”. Moreover, the discovery of the Phylum Vetulicolia may also throw new light on the origin of deuterostomes. This extinct group with simple gill slits might represent one of the roots in the deu- terostome lineage, as the evidence of molecular biology and developmental biology has predicted. Here the first discovery of tiny vetulicolians from the Chengjiang Lagerst?tte is re- ported. The evolutionary trend from the giant to the small might represent a special adaptation in early animal history. Since all vetulicolians share similar characters in their ante- rior section (pharynx), and on the basis of differences in their posterior section, a new classification system is proposed, with a new class, the Heteromorphida erected. As both the “root” group vetulicolians and the “top” group vertebrates in the early deuterostome lineage, as well as those members in between, such as vetulocystids, yunnanozoans, cephalo- chordates and urochordates, hav

关键词： Phylum Vetulicolia Beidazoon roots and early evolution of deuterostome lineage Early Cambrian Chengjiang Lagerst?tte fauna.

NUMERICAL STUDY OF SOLITARY WAVE FISSION OVER AN UNDERWATER STEP

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Journal of Hydrodynamics 2008年第3期20卷 398-402页

作者： LU Ji YU xi-ping state Key laboratory of Hydroscience and Engineering Department of Hydraulic Engineering TsinghuaUniversity Beijing 100084 China

Solitary wave fission over an underwater step is numerically investigated. The numerical model is based on the enhanced Boussinesq equations, which appropriately represent both the nonlinearity and dispersivity of surface water waves. The finite difference method defined on the staggered grid in space with an implicit scheme for time stepping is employed for the numerical solution of the governing equations. It is demonstrated that Boussinesq type equations, though they are vertically integrated, can describe the details of the solitary wave fission process with very good accuracy. Numerical results of the reflected and transmitting wave heights, the number of solitons emitted from the transmitting wave and their amplitudes all agree very well with the analytical solution derived from KdV equation by virtue of a linear long wave approximation in the vicinity of the underwater step.

关键词： enhanced Boussinesq equations solitary wave fission underwater step numerical computation

Boron isotopic fractionation in laboratory inorganic carbonate precipitation:Evidence for the incorpora-tion of B(OH)_3.into carbonate

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Science china Earth Sciences 2008年第12期51卷 1776-1785页

作者： xiAO YingKai1,2, LI HuaLing1,3. LIU WeiGuo4, WANG xiuFang1 & JIANG ShaoYong5 1 Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, xining 810008, china 2 state Key laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, china 3.Nanjing Institute of geology and Mineral Resources, Nanjing 210016, china 4 state Key laboratory of Loess and Quaternary geology, Institute of Earth Environment, Chinese Academy of Sciences, xi’an 710075, china 5 state Key laboratory for Mineral Deposits Research, department of Earth Sciences, Nanjing {13., Nanjing 210093. china 1. Qinghai Institute of Salt Lakes Chinese Academy of Sciences Xining 810008 China 2. state Key laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China 3. Nanjing Institute of geology and Mineral Resources 210016 Nanjing China 4. state Key laboratory of Loess and Quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 5. state Key laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China

A laboratory inorganic carbonate precipitation experiment at high pH of 8.96 to 9.3. was conducted, and the boron isotopic fractionations of the precipitated carbonate were measured. The data show that boron isotopic fractionation factors (αcarb-3. between carbonate and B(OH)3.in seawater range 0.93. and 0.965, with an average value of 0.953. Our results together with those reported by Sanyal and collabo-rators show that the αcarb-3.values between carbonate and B(OH)3.in solution are not constant but are negatively correlated with the pH of seawater. The measured boron isotopic compositions of carbonate precipitation (δ11Bcarb) do not exactly lie on the best-fit theoretical δ 11B4-pH curves and neither do they exactly parallel any theoretical δ 11B4-pH curves. Therefore, it is reasonable to argue that a changeable proportion of B(OH)3.with pH of seawater should also be incorporated into carbonate except for the dominant incorporation of B(OH)4- in carbonate . Hence, in the reconstruction of the paleo-pH of sea-water from boron isotopes in marine biogenic carbonates, the use of theoretical boron isotopic frac-tionation factor (α4-3. between B(OH)4- and B(OH)3.is not suitable. Instead, an empirical equation should be established.

关键词： boron isotopic fractionation biogenic carbonate B(OH)3 incorporation