干旱半干旱地区土地沙漠化信息系统的设计与应用

“数字地球”战略的提出得到各界人士的广泛关注,并从各自专业角度献计献策。但“数字地球”战略的实施必须以区域或专题为切入点。本文从我国干旱半干旱地区沙漠化比较严峻及西部大开发以生态环境建设为目标的背景出发,结合研究区的自然、人文特征,设计干旱半干旱地区沙漠化信息系统的总体结构、功能、模型,系统包括数据库管理子系统、土地沙漠化信息查询子系统、模型库管理子系统等。系统设计的同时选择典型示范区进行了实践。结果表明,系统在其数据项相关性方面已满足本专题GIS系统的功能和模型的要求,本系统可为生态环境恶化、土地沙漠化预测与评估以及决策部门及时采取防治措施和对策。提供迅速、动态的信息和技术支撑。     

初至波菲涅尔体地震层析成像

根据地震波传播的有限频理论,对于某个特定震相的观测信息,不仅射线路径上的点对该信息具有影响,射线领域上的其他点对接收信息也具有影响,这种影响可以用核函数来表达.本文基于波动方程的Born近似与Rytov近似,给出了非均匀介质情况下初至地震波振幅与走时菲涅尔体层析成像单频、带限层析核函数的计算方法.通过对均匀介质情况下初至地震波菲涅尔体层析成像核函数解析表达式的理论模型实验与分析,给出了不同维度振幅、走时单频菲涅尔体的空间分布范围,进而给出了带限菲涅尔体边界的确定方法.将本文的走时菲涅尔体层析成像理论应用于表层速度结构反演中,理论模型试验与实际资料处理结果表明,初至波菲涅尔体地震层析成像方法比传统的初至波射线层析成像理论具有更高的反演精度.     

A typical example of the application of the `Multi-Cloud Model'method to the asymmetric profiles processing

Multi-Cloud Model(MCM) is an effective method for dealing with asymmetric profiles of spectral line formed by active objects on the sun. A typical example is given for the application of the MCM method in this paper. The H _β spectral data of a large post-flare loop (PFL) system which occurred on the solar western limb are obtained with MW-SSHG at the Yunnan Observatory and analysed based on the MCM method. The line-of-sight velocity fields observed in different times are derived and discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study on kinetics of cathodic reduction of dissolved oxygen in 3.5% sodium chloride solution

Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3. 5% sodium chloride(NaCl)solutions by cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS), rotating disk electrode(RDE)and rotating ring-disk electrode(RRDE). The cyclic voltammetric results demonstrated the cathodic process on Q235 carbon steel in O2-saturated 3. 5% NaCl solution contains three reactions:dissolved oxygen reduction, iron oxides reduction and hydrogen evolution. The peak potential of oxygen reduction reaction(ORR)is-0. 85 V vs Ag/AgCl, 3 molL-1 KCl. The E1S results indicated that the ORR occurring on Q235 carbon steel is a 4-electron process and that no finite diffusion is caused by the intermediate of H2O2 produced by ORR. The RDE and RRDE voltammograms confirmed the EIS results and it was found that the number of transferred electrons for ORR was nearly 4, I. E. , dissolved oxygen reduced to water.     

江西省城市化水平与城市效率相关分析

在对江西省城市化水平分析的基础上,应用城市效率指标,对江西省11个地级市的城市效率作了定量分析,总结了其地域分异规律,并就江西省城市化水平与城市效率进行了相关分析研究。结果表明,江西省的城市化水平与城市效率的相关性总体一致,符合“城市规模效率梯度”现象。在提高城市集聚功能,培育城市群（带）,促进城市可持续发展以及欠发达地区的发展方面提供了一些有益的参考和建议。     

渤海湾盆地构造及其对油气的控制

裂谷盆地是夭折的裂谷。在其所形成的伸展构造中蕴藏有丰富的石油及天然气。渤海湾盆地是典型的裂谷盆地,按其形成和发展可划分为五个阶段:即萌芽阶段;初成阶段;沉陷阶段;回返阶段及裂谷后沉陷阶段。这五个阶段的特征在深陷带地区表现最为明显,其中沉陷阶段和回返阶段对油气的形成及聚集关系最为密切。渤海湾盆地的构造演化、岩浆活动、断裂变动及油气的形成、运移、聚集等是一个有机整体不可分割的部分。它们有着内在联系及一定的规律性,对这方面进一步深入研究将会对油气勘探工作起着指导作用。     

Ore Geology, Fluid Geochemistry and Genesis of the Shanggong Gold Deposit, Eastern Qinling Orogen, China

Abstract. The Shanggong Au deposit in the Xiong'er Terrane, East Qinling, has reserves of about 30 t Au, making it one of the largest orogenic‐type Au deposits hosted in volcanic rocks in China. The deposit is hosted in the andesitic assemblage of the Xiong'er Group of 1.85?1.4 Ga. Three stages of hydrothermal ore‐forming processes are recognized, Early (E), Middle (M) and Late (L), characterised by quartz‐pyrite, polymetallic sulfides and carbonate‐quartz, respectively. Homogenization temperatures of fluid inclusions are between 380‐320d?C for the E‐stage, 300‐220d?C for the M‐stage and 200‐120d?C for the L‐stage. The composition of fluid inclusions changed from CO₂‐rich in the E‐stage to CO₂‐poor L‐stage. The M‐stage fluid has the highest contents of cations and anions (e.g., SO₄^2‐, Cl¹, K+), the highest (K+Na)/(Mg+Ca) and lowest CO₂/H₂O ratios, which probably resulted from CO₂ phase separation. This, together with the alkaline and reducing conditions, as indicated by highest pH and lowest Eh values, is most conducive to the deposition of polymetallic sulfides and native elements such as Au, Ag and Te. H‐O isotope systematics indicate that ore fluids evolved from deep‐sourced through to shallow‐sourced, with the M‐stage being a mixing phase of these two fluid‐systems. Nineteen δ¹⁸O_W values, from 4.2 to 13.4 %o, averaging 8.1 %o, suggest that the E‐stage fluids derived from metamorphic devolatilization of sedimentary rocks at depth. Comparison of the H‐O isotope systematics between the Shanggong deposit and the main lithologies in the Xiong'er Terrane, shows that neither these nor the underlying lower crust and mantle, or combinations thereof, could be considered as the source of ore fluids and metals for the Shanggong Au deposit. Instead, a source which meets the isotopic constraints, is a carbonaceous carbonate‐sandstone‐shale‐chert (CSC) sequence, which is present in the Guandaokou and Luanchuan Groups in the south of the Xiong'er Terrane. This conclusion is supported by thirteen high δ¹⁸O values of the Meso‐Neoproterozoic strata south of the Machaoying fault, and the high δ¹⁸O_W values calculated for their possibly metamorphic fluids. It can be also supported by previous observation that the Guandaokou and Luanchuan Groups were underthrust beneath the Xiong'er Terrane, during the Mesozoic collision between the Yangtze and Sinokorean continents. Available isotope ages, together with geological field data, constrain the timing of the Au metallogenesis between 250?110 Ma. This metallogenesis and associated granitic magmatism, can be related to the Yangtze‐Sinokorean continental collision that resulted in the formation of the Qinling Orogen. This collision event progressed from early compression (Triassic to Early Jurassic), through middle compression‐to‐extension transition (Late Jurassic to Early Cretaceous), to late extension (Cretaceous). These three stages in the evolution of the Qinling Orogen form the basis of an ore genesis model that combines collisional orogeny, metallogeny and fluid flow (CMF model). These three evolutionary stages correspond to the three‐stages of ore‐forming fluids of the Shanggong Au deposit. We conclude that the formation of the Shanggong Au deposit is a result of the Mesozoic northward intracontinental A‐type subduction along the Machaoying fault during Yangtze‐Sinokorean continental collision, which led to the metamorphic devolatilization of the CSC sequence, thereby providing both fluids and metals.     

近40年甘肃省耕层土壤有机碳时空分异及影响因素

区域耕层土壤有机碳（Soil Organic Carbon, SOC）调查是明确全球土壤碳储量和认识土壤碳循环的重要任务。利用甘肃省1980s、2000s、2020s等3个时期的耕层土壤调查数据,通过计算耕层土壤有机碳密度（Soil Organic Carbon Density,SOCD）,估算了甘肃省耕层有机碳储量。结果显示：（1）1980s、2000s、2020s甘肃省耕层SOC储量分别为97.68、109.14、123.13 Tg,近40年固碳总量约为25.45 Tg,固碳速率为0.012±0.01 kg·m^-2·a^-1,说明当前的农田管理措施有利于研究区耕地土壤长期固碳;40年间河西绿洲灌区、黄土高原区和陇南山地区耕层SOC储量呈增加趋势,甘南高原呈下降趋势。（2）从不同土壤类型来看,黄棕壤固碳速率最大,栗钙土最小。（3）近40年间甘肃省耕层SOC储量总体呈递增趋势,化肥、有机肥施用量以及秸秆还田量的持续增加,提高了作物归还量,进而增加了耕层有机物质含量,最终促进了耕层SOC的累积。     

Thermal-mechanical Influences and Environmental Effects of Expressway Construction on the Qinghai-Tibet Permafrost Engineering Corridor

The Qinghai-Tibet Engineering Corridor (QTEC) is a strategic passage between Tibet and central China. In the past half century, several major projects have been built in this narrow corridor with vulnerable geoenvironment. Along with a new round of economic development of the Tibet autonomous region, some major linear projects including expressway, double-tracking railway, high voltage power transmission line have been incorporated into the national development planning within the corridor, and especially the expressway construction is imminent now. In the QTEC, permafrost is a controlling factor of geological environment, which will impose great restrictions on engineering construction. In turn, engineering construction will induce significant effects on permafrost geological environment. With more and more linear infrastructures crowding into the QTEC, the thermal interaction among permafrost engineering and engineering disturbance on permafrost thermal-mechanical regime will be more significant. With respect to this issue, a research program focusing on thermal-mechanical influences and environmental effects of expressway construction on the Qinghai-Tibet permafrost engineering corridor was started and supported by the National Natural Science Foundation of China. In this paper, the research significance, key scientific issues, main research contents and goals of the program are introduced so as to provide some references for related researchers and engineers.