Physicochemistry and Mineralogy of Storm Dust and Dust Sediment in Northern China

Dust sediments collected from 1995 to 1998 in Beijing, Dunhuang, Inner Mongolia, Kashi, the Kunlun Mountains, Lanzhou, Ningxia, the Taklimakan Desert, and Xi‘an, China, were characterized in terms of their physical, chemical, and mineralogical properties. Most aerosols and dust analysed ranged in texture from silty clay to clay loam. Their median particle diameters (Mds) generally ranged between 5 to 63μm,coinciding with those of loess from central China and the finest sand from northwestern China. The dust sediments were characterized by a predominance of SiO2 and Al2O3, followed by K2O. Their SiO2/Al2O3and K2O/SiO2 molar ratios ranged from 5.17 to 8.43 and from 0.009 to 0.0368, respectively. The mass concentration spectrum during a dust storm showed a single peak, rather than the triple peak generally observed under clear sky conditions. The dominant minerals were chlorite, illite, calcite, and dolomite.These physical, chemical, and mineralogical properties were consistent with those of aeolian soils and loess in western and central China. The results suggest that aerosols and fine-gained fractions of dust sediments collected in northern China are mainly composed of soil material transported from the arid and semiarid regions of China and Mongolia by prevailing winds. The rate of deposition and properties of dust falling on eastern China were strongly influenced by meteorological conditions, season, latitude, longitude, and altitude of the sampling sites.     

High-resolution satellite image segmentation using Hölder exponents

Texture in high-resolution satellite images requires substantial amendment in the conventional segmentation algorithms. A measure is proposed to compute the Hölder exponent (HE) to assess the roughness or smoothness around each pixel of the image. The localized singularity information is incorporated in computing the HE. An optimum window size is evaluated so that HE reacts to localized singularity. A two-step iterative procedure for clustering the transformed HE image is adapted to identify the range of HE, densely occupied in the kernel and to partition Hölder exponents into a cluster that matches with the range. Hölder exponent values (noise or not associated with the other cluster) are clubbed to a nearest possible cluster using the local maximum likelihood analysis.     

东昆仑东段三叠纪岩浆岩Nd–Hf同位素组分特征、物源演变规律及其构造背景

作为中央造山系西段的重要组成部分,东昆仑造山带以大面积区域性展布的三叠纪岩浆岩为鲜明特色。依据收集的东昆仑东段三叠纪岩浆岩96件锆石U–Pb年代学数据,限定三叠纪岩浆作用时间为252～212 Ma。结合岩石组合,将其进一步划分为早（252～238 Ma）、中（238～226 Ma）、晚（226～212 Ma）3期,其中岩浆活动峰值为早期（252～238 Ma）。Nd同位素数据（106件）统计结果表明：东昆仑东段三叠纪岩浆岩εNd(t)值为–9.4～–1.7,大多为–6.5～–3.0;Nd模式年龄TDM(Nd)为0.72～1.88 Ga,大多为1.00～1.80 Ga。Hf同位素数据（全岩、锆石;41件）统计结果表明：东昆仑东段三叠纪岩浆岩εHf(t)值变化较大（–8.4～+12.4）,主要为–4.5～+2.0;地壳模式年龄TDMC(Hf)值为0.49～ 1.80 Ga,大多为1.15～1.55 Ga。整体而言,三叠纪岩浆岩物源以中元古代壳源物质的再造为主,新生地壳（＜1.0 Ga）和古元古代地壳有所参与,但比例小。从岩浆活动早期（252～238 Ma）到中期（238～226 Ma）再到晚期（226～212 Ma）,εNd(t)值在岩浆活动早期（特别是在早三叠世）较高,正的εHf(t)值占据很大比例,物源中存在较多的新生物质;中期以较低的εNd(t)值和负的εHf(t)值为主,Hf模式年龄显示出现古元古代物质;晚期Nd–Hf模式年龄揭示较古老的壳源组分增多。这种岩浆岩物源演变趋势,与东昆仑东段三叠纪具俯冲到同碰撞再到碰撞后的构造演化背景一致。     

干涸尾闾湖盆区泥漠地表磨蚀释尘特征

沙粒的表面磨蚀效应是地表产尘、释尘的重要机制,针对干湖盆泥漠地表开展磨蚀释尘实验研究,对理解干湖盆地表风蚀过程及盐碱尘暴形成机理具有重要意义。对采自西居延海干涸湖盆泥漠地表土样进行室内磨蚀模拟实验,研究了不同粒级（细、中、粗）沙粒不同落沙角度（30°,45°,60°）的磨蚀效应。结果表明：（1）泥漠地表磨蚀实验中能够产生明显释尘效应的沙粒粒级阈值为中沙（0.25 mm<M_d<0.50 mm）;（2）磨蚀粒径粒级相同时,磨蚀角度会对泥漠地表磨蚀释尘速率产生影响,磨蚀量的角度排序为60°>30°>45°,但同一粒级3种角度下的磨蚀释尘率差异不显著。（3）磨蚀角度为45°时,计算了泥漠地表的质量磨蚀率与能量磨蚀率,其中中沙为0.04 g·kg^-1、0.43 g·J^-1,粗沙为0.08 g·kg^-1、0.74 g·J^-1,极粗沙为0.26 g·kg^-1、2.54 g·J^-1;在磨蚀沙粒粒级倍增而磨蚀角度不变情况下,泥漠地表磨蚀释尘率与能量磨蚀率未发生正比例线性增长变化。     

Sequential city growth: Theory and evidence from the US

City growth patterns are attracting more attention in urban geography studies. This paper examines how cities develop and grow in the upper tail of size distribution in a large-scale economy based on a theoretical model under new economic geography framework and the empirical evidence from the US. The results show that cities grow in a sequential pattern. Cities with the best economic conditions are the first to grow fastest until they reach a critical size, then their growth rates slow down and the smaller cities farther down in the urban hierarchy become the fastest-growing ones in sequence. This paper also reveals three related features of urban system. First, the city size distribution evolves from low-level balanced to primate and finally high-level balanced pattern in an inverted U-shaped path. Second, there exist persistent discontinuities, or gaps, between city size classes. Third, city size in the upper tail exhibits conditional convergence characteristics. This paper could not only contribute to enhancing the understanding of urbanization process and city size distribution dynamics, but also be widely used in making effective policies and scientific urban planning.     

新疆和田河流域柽柳沙堆的生物地貌发育过程

Tamarix nabkha is one of the most widespread nabkhas,distributing in the arid region of China.Based on the observations outdoors and the simulation experiments in laboratories,analysis in this paper refers to the biological geomorphologic features and growth process of Tamarix nabkhas in the middle and lower reaches of the Hotan River,Xin- jiang.And the results indicate that the ecological type of Tamarix in the study area is a kind of Tugaic soil habitat based on the deep soil of the Populus Diversifolia f...     

人类世可持续发展背景下的远程耦合框架及其应用

在全球一体化进程不断加深的背景下,国家与地区之间的联系日益紧密,产生了一系列跨国家、跨地区、多尺度的社会—经济—环境影响,远程耦合（Telecoupling,社会、经济、环境的远距离相互作用）科学概念和综合框架的提出为解决上述问题提供了新方法和新途径。为更好促进远程耦合综合框架的正确使用和规范推广,本文系统解析了远程耦合综合框架,厘清各组成部分的定义和功能,梳理了框架的应用现状;通过对3个中国典型案例的阐释,展示了远程耦合综合框架的使用方法、结果分析及由此得出的科学意义和政策价值;最后描述了远程耦合综合框架使用中需要重点关注的问题,并对其应用前景进行了展望。远程耦合综合框架的推广应用有助于以跨国家、跨地区、多尺度的视角,重新审视多个人类与自然耦合系统的相互作用,揭示隐藏的远距离地理空间作用的科学价值,服务于有关政策的制定和实施,促进全球社会、经济、环境的可持续发展。     

白令海峡治理的合作机制研究

近年来随着北极冰盖的融化,北极通航已成为可能,而白令海峡作为北极航道重要的出口/入口,其战略地位也将逐步显现并被各国关注。在讨论白令海峡的治理与合作时,首先要明确白令海峡是用于国际航行的海峡,而作为海峡沿岸国的美国和俄罗斯对于白令海峡的管控与合作将成为影响未来北极航行的重要因素。为同时保障海峡沿岸国与使用国的利益,可借鉴马六甲海峡的治理经验,在现有治理机制的基础上进一步深化海峡沿岸国与海峡使用国的合作机制。中国作为海峡使用国也有必要积极参与白令海峡的合作治理。     

Aluminum Consumption and Economic Growth: Evidence from Rich Countries

The article attempts to test the aluminum consumption–economic growth nexus for 20 rich economies for the period 1970–2009. Various panel data unit root and cointegration tests are applied. The series are found to be integrated of order one and cointegrated, especially after controlling for cross-sectional dependence. Moreover, the Blundell–Bond system generalized methods-of-moments is employed to conduct a panel causality test in a vector error-correction mechanism setting. Unidirectional causality running from aluminum consumption to real GDP is uncovered in the short-run, while real GDP is found to Granger-cause aluminum consumption in the long-run. Moreover, a 1% increase in real GDP generates an increase of 0.44% in aluminum consumption in the long-run for the whole panel.     

Automatic mapping of lunar landforms using DEM-derived geomorphometric parameters

Developing approaches to automate the analysis of the massive amounts of data sent back from the Moon will generate significant benefits for the field of lunar geomorphology. In this paper, we outline an automated method for mapping lunar landforms that is based on digital terrain analysis. An iterative self-organizing (ISO) cluster unsupervised classification enables the automatic mapping of landforms via a series of input raster bands that utilize six geomorphometric parameters. These parameters divide landforms into a number of spatially extended, topographically homogeneous segments that exhibit similar terrain attributes and neighborhood properties. To illustrate the applicability of our approach, we apply it to three representative test sites on the Moon, automatically presenting our results as a thematic landform map. We also quantitatively evaluated this approach using a series of confusion matrices, achieving overall accuracies as high as 83.34% and Kappa coefficients (K) as high as 0.77. An immediate version of our algorithm can also be applied for automatically mapping large-scale lunar landforms and for the quantitative comparison of lunar surface morphologies.