塔克拉玛干沙漠腹地散射辐射特征

本文利用塔克拉玛干沙漠大气环境观测试验站2010年总辐射、散射辐射、直接辐射观测资料分析了塔克拉玛干沙漠腹地的散射辐射变化特征和散射辐射与晴空指数、大气质量的关系。结果表明:散射辐射年曝辐量为3 628.5 MJ·m-2,占年总辐射曝辐量的59.5%,高于全国平均值;散射辐射夏季大（468.3 MJ·m-2）、冬季小（120 MJ·m-2）,日最高值基本出现在正午,夏季最高辐照度达719.2 W·m-2。与晴空指数大于0.7时相比,晴空指数小于0.7时,秋、冬季散射辐射增加。晴空指数>0.3时,散射辐射与总辐射的比值随晴空指数的增加而呈线性递减;晴空指数<0.3时,散射辐射与天文辐射的比值随晴空指数的增加基本呈直线增加。散射辐射随太阳高度角的增大呈指数递增。散射辐射的变化主要集中在大气质量小于5的范围内且随大气质量的增加而迅速降低。     

塔克拉玛干沙漠南缘3种荒漠植物光合特性的比较

在2008年6、7和8月中旬,以塔克拉玛干沙漠南缘固氮植物骆驼刺（Alhagi sparsiftia Shap．）和非固氮植物柽柳（Tamarx ramossimaLedeb．）、花花柴（Karelinia caspica Less．）为研究对象,研究了两种类型植物的净光合速率、光响应、CO：响应模型参数、叶绿素和叶氮...     

晚更新世晚期以来古尔班通古特沙漠南部的气候环境演化

本文通过对古尔班通古特沙漠南部的一个钻孔剖面沉积物沉积物沉积特征的分析 ,证明该沙漠南部地区在晚更新世晚期气候相对寒冷 ,并有两次气候偏湿波动 ;全新世时期 ,该区气候以温暖干旱为主 ,全新世中期有一次明显的气候偏湿波动。     

巴丹吉林沙漠晚更新世沉积物矿物学特征及其指示意义

巴丹吉林沙漠是研究亚洲内陆干旱化等古环境问题的重要窗口。以沙漠东南缘巴润宝日陶勒盖剖面为研究对象,通过详细的薄片矿物学、X射线衍射半定量及粒度等方法指标,综合分析沉积物的结构成熟度和成分成熟度等矿物学特征,恢复该地区在晚更新世沉积环境变化。结果表明：（1） 66.8 ka之前沉积的矿物碎屑分选性好、磨圆较好,稳定矿物含量高;66.8 ka之后,矿物分选性差、磨圆差,稳定矿物含量均下降,粘土矿物增加。（2） 66.8 ka之前沉积物以中砂为主,66.8 ka之后以细砂为主。研究表明巴丹吉林沙漠东南缘66.8 ka前后存在一次沉积环境突变,由风沙沉积转变为湖相沉积,可能代表了一次典型的东亚夏季风增强事件,推测与低纬西太平洋温度升高相关。对于巴丹吉林沙漠东南缘沉积物矿物学的相关认知有助于理解沙漠中沉积环境的转换过程及其驱动因子,并为重建沙漠千年尺度的古环境与古气候演变提供数据参考。     

Analysis of the Surface Energy Closure for a Site in the Gobi Desert in Northwest China

The heat storage terms over an ideal(non-vegetated) horizontal desert surface may be very important and easily neglected in surface energy balance studies.In this paper,based on a field experiment over the Gobi Desert in the middle part of the Hexi Corridor in Northwest China(39 05 N,100 16 E;1457-m elevation),we studied the energy budget closure and evaluated the contribution of the heat storage terms to the closure of the surface energy balance.There were imbalances of 8% and 15% in summer and winter,respectively,if the heat storage terms were not taken into account.For both seasons,a nearly perfect result of the surface energy closure(99%) was obtained by inclusion of the estimates of heat storage terms.The soil heat storage term improved the surface energy imbalance by about 6% in summer and 13% in winter,and the air enthalpy storage term improved it by about 0.6% in summer and 1% in winter,while the contribution of the atmospheric moisture changes could be ignored.     

Evaluation of redox-sensitive metals in marine surface sediments influenced by the oxygen minimum zone of the Humboldt Current System,Northern Chile

Upwelling coastal systems can be used to understand how dissolved oxygen and biological productivity control the accumulation of redox-sensitive metals in marine sediments. The aluminium (Al), cadmium (Cd), iron (Fe), nickel (Ni), molybdenum (Mo), vanadium (V), total organic carbon (TOC), total nitrogen (TN) and total sulfur (TS) contents in surficial sediment collected from different water depths (30, 70, and 120?m) in three northern Chilean bays influenced by coastal upwelling and oxygen minimum zones (OMZs) were measured. Principal component analysis (PCA), cluster analysis, and Spearman?s rank correlation were used to identify the mechanisms responsible for the redox-sensitive metal accumulation. The content of redox-sensitive metals and organic components in sediment increased with increasing water column depth, whereas lithogenic metals decreased. In the Mejillones del Sur and Caldera bays, the enrichment factors of the redox-sensitive metals showed enrichment for all metals with depth. The Cd and V enrichments are mainly the product of biogenic flow to the seabed, and the Mo and Ni enrichments are due to preservation under low subsurface oxygen conditions. Sulfate reduction is not an important mechanism in the accumulation of redox-sensitive metals in the sediment of the three bays. The PCA showed that the behaviors of the redox-sensitive metals and organic components reflect differences in the effects of the OMZ in sediment along the coast of northern Chile, with a more intense OMZ in Mejillones del Sur bay and weaker OMZs in Caldera and Inglesa bays. However, the high degree of enrichment in redox-sensitive metals in Caldera Bay can be attributed to the intense activity of the mining industry near the bay, a situation that produces geochemical behavior similar to that observed in Mejillones del Sur Bay.     

库布齐沙漠南缘抛物线形沙丘表面风速与输沙率的变异

以库布齐沙漠南缘典型抛物线形沙丘为研究对象,选取3个沙丘前端活动区的纵断面和一个贯穿两翼及翼间平地的横断面,同步观测各个断面的风速与输沙率,讨论抛物线形沙丘表面形态-动力学过程。结果显示,沙丘前端活动区3个纵断面的风速和输沙率遵循一般变化规律,即沿迎风坡上升逐渐增加,至丘顶及附近达到最大,并在背风侧降低;二者在3个纵断面上的变化趋势一致,但具体变化形式不同,沙丘表面动力与输沙过程存在较大的空间异质性。沙丘两翼具有纵向沙丘的动力学性质,翼体两侧风速和输沙率具有对称性。该沙丘沙源匮缺,前端活动区主要依靠两翼内侧侵蚀提供沙源。受沙丘形状和植被等因素影响,坡脚及坡下部风速与输沙率之间没有相关性,因此简单的风速放大率和输沙率变化程度无法准确揭示该类型沙丘表面复杂的形态-动力学关系。     

古尔班通古特沙漠风沙活动特征与线形工程安全研究

古尔班通古特沙漠是我国第二大沙漠，沙丘类型以固定和半固定纵向沙垄为主。垄间和坡中下部沙面较为稳定，仅在沙垄顶部存在10—40m宽度不等的流动带，风沙活动规律独特。近年来在沙漠腹地修筑的公路、引水渠等线形工程，不可避免地造成沙垄切剖和保护层破环，所引发的工程安全问题引起了人们的普遍关注。通过风况分析和实地观测，对沙漠腹地风沙活动特征进行了初步研究，同时对线形工程风沙危害进行监测，在此基础上提出现有防护体系存在的主要问题与对策。     

Laboratory simulation of salt weathering processes in arid environments

The equipment and techniques being used at Bedford College, London to simulate salt weathering processes in deserts are described in the context of a general discussion of the nature of salt weathering processes and approaches to studying them. An experiment based on the equipment and techniques is described: it is designed to test the durability of three building stones in the presence of several different saline solutions under conditions of surface temperature and relative humidity that are considered typical of hot deserts. The experiment, the first of a series, shows that Na₂SO₄ is the most effective of the salts used, and that susceptibility of the rocks to weathering is related to such rock properties as porosity, microporosity and water absorption capacity.     

Mineralogy,geochemistry and age dating of shear zone-hosted Nb-Ta-, Zr-Hf-, Th-, U-bearing granitic rocks in the Ghadir and El-Sella areas,South Eastern Desert,Egypt

The rare metal minerals of mineralized altered granites within the Ghadir and El-Sella shear zones, are represented by betafite, U-minerals (uraninite and uranophane), zircon, monazite, xenotime, and rutile in the Ghadir shear zone. While they are columbite-tantalite minerals as ferrocolumbite, pyrochlore, and fergusonite, Th-minerals (cheralite, uranothorite, and huttonite monazite), Hf-zircon, monazite and xenotime in the El-Sella shear zone. Hf-zircon in the El-Sella and Ghadir shear zones (increasing from the core to the rim) contains high inclusions of U-Th, and REE minerals such as cheralite, uranothorite, huttonite monazite and xenotime especially in the El Sella shear zone. The rare-metal minerals, identified from peralkminous granites of the shear zones are associated with muscovite, quartz, chlorite, fluorite, magnetite, and biotite that are restricted to the two shear zones. Uraninite (low Th content) occurring in the Ghadir shear zone indicates the hydrothermal origin, but there are thorite, uranothorite, cheralite, and Hf-zircon in the El Sella shear zone, also indicating the hyrothermal proccess after magmatic origin. Compositional variations of Ta/(Ta+Nb) and Mn/(Mn+Fe) in columbite from 0.07-0.42 and 0.04-0.33, respectively, and Hf contents in zircon are so high as to be 12%, especially in the rim in the El Sella shear zone. This feature re-flects the extreme degree of magmatic fractionation. Four samples from the altered granites of the Ghadir shear zone also are very low in TiO2 (0.04 wt%-0.17 wt%), Sr [(82-121)×10-6], and Ba [(36-380)×10-6], but high in Fe2O3T (0.46 wt%-0.68 wt%), CaO (0.64 wt%-1.23 wt%), alkalis (8.59 wt%-8.88 wt%), Rb [(11-203)×10-6], Zr [(98-121)×10-6], Nb [(9-276)×10-6], Ta [(2-139)×10-6], U [(14-63)×10-6], Th [(16-105)×10-6], Pb [(13-32)×10-6], Zn [(7-8)×10-6], Y [(15-138)×10-6], Hf [(3-9)×10-6], and ∑REE [(81-395)×10-6, especially LREE [(70-322)×10-6]. They are very high in Zr/Hf (15.07-85.96) and Nb/Ta (7.17-21.48), and low in Rb/Sr (2.56-3.36) and Th/U (0.096-3.36). Four samples of the altered granites from the El Sella shear zone are very low in TiO2 (0.23 wt%-0.38 wt%), Sr [(47-933)×10-6], and Ba [(82-175)×10-6] , with high Fe2O3T (1.96 wt%-2.87 wt%), CaO (0.43 wt%-0.6 wt%), alkalis (4.46 wt%-10.7 wt%), Rb [(109-313)×10-6], Zr [(178-1871)×10-6], Nb [(11-404)×10-6], U [(56-182)×10-6], Th [(7-188)×10-6], Ta [(0.5-57)×10-6], Pb [(12-28)×10-6], Zn [(1-13)×10-6], Y [(62-156)×10-6], Hf [(3-124)×10-6], and ∑REE [(101-184)×10-6], especially HREE [(7-139)×10-6]. This is consistent with the very fractionated, fluorine-bearing granitic rocks that were altered and sheared in the El Sella shear zone. Zr/Hf (14.23-39.79) and Nb/Ta (1.98-7.01) are very high, and Rb/Sr (0.14-1.7) and Th/U (0.25-2.5) are low in the Ghadir shear zone. Field evidence, textural relations, and the composi-tion of ore minerals suggest that the main mineralizing event was magmatic (615+/-7 Ma, and 644+/-7 Ma CHIME monazite), especially in the El Sella shear zone, with later hydrothermal alteration and local remobilization of the high-field-strength elements.