1999年夏季中昆仑山北坡诸河冰雪大洪水及其成因分析   总被引：2，自引：1，他引：2  

毛炜峄  玉素甫·阿布都  程鹏  董克鹏 《冰川冻土》2007,29(4):553-558

1999年盛夏中昆仑山北坡大多数河流出现了有正式水文记录以来的最大洪峰,各河流最大洪峰出现时间存在不一致性,洪峰变化复杂.应用主要河流出山口水文站的逐日流量和降水量,和田气象站的逐日0℃层高度,500 hPa气温以及NCEP/NCAR 500 hPa高度场资料,分析了1999年夏季中昆仑山北坡诸河出现的历史特大洪水特性及其气象成因.这次特大洪水是高空持续高温引起的冰雪融水与产流区出现的暴雨共同作用下的混合型洪水.洪水前期春季到初夏该区域山区降水偏多,高空气温和0℃层高度持续偏低,对高山区的积雪积累极为有利;7月底至8月初和田高空气温和0℃层高度迅速上升并维持数日,使冰雪快速消融,同时山区出现大降水是引发洪水的直接气象成因.在青藏高原东部柴达木盆地上空存在有500 hPa稳定高压,使中亚副热带大槽东移中昆仑山北坡是这次特大洪水发生的环流系统特点.  相似文献   

新疆东准噶尔北部扎河坝富碱花岗质岩石矿物学特征及物理化学条件     

张东阳  高阳  苏慧敏  王鹏 《矿物岩石》2007,27(4):30-38

新疆东准噶尔北部扎河坝富碱花岗质岩石分布于乌伦古大断裂与额尔齐斯-玛因鄂博大断裂之间。富碱花岗岩类有石英碱性正长岩、碱性长石花岗岩、石英二长斑岩及碱性长石正长岩等岩石类型。在详细的显微镜观察基础上,全岩分析和电子探针分析结果表明,富碱花岗质岩中的矿物组合是碱性长石 石英 钠铁闪石 霓辉石,以出现高硅、富碱、贫铝、低钙、低镁、高铁、高锰、贫水为特征。铁钛氧化物温度计估算出的富碱花岗岩体结晶温度在650℃~755℃之间,氧逸度为10-17.17Pa~10-14.39Pa,结合钠铁闪石的特征,碱性岩浆演化后期存在着明显的水-岩作用,扎河坝富碱花岗质岩石形成于低压、高氧逸度、中高温环境,反映了相对开放、浅成的形成环境。  相似文献   

南极普里兹湾夏季海冰边缘区内破碎海冰的分布特征          下载免费PDF全文

卢鹏  李志军  张占海  董西路 《水科学进展》2007,18(6):884-892

基于中国第21次南极考察中获得的69°00'S、76°24'E附近普里兹湾夏季海冰边缘区内破碎海冰的航拍照片,利用图像处理的方法从中提取了破碎海冰的若干几何参数,得到了海冰边缘区内随着与开阔水域距离增大,海冰面积、平均钳测直径等几何参数的变化规律。并按其尺寸的变化规律将海冰边缘区划分为边界区、过渡区和内部区三部分,其变化和波浪在冰边缘区中的衰减过程紧密相关。圆度的变化则说明海冰边缘区中海冰磨损最充分的地方是在冰间相互作用最明显的过渡区。另外,一种改进的幂函数分布和Weibull分布用来对破碎海冰尺寸的累积频率进行拟合,分布函数中各参数的变化情况很好的反映了海冰边缘区内破碎海冰的分布变化。其中,参数L_r随着与开阔水距离增加而增大(说明由于波能衰减导致可以出现的破碎海冰最大尺寸的增加);尺度参数L₀随着与开阔水距离增加而增大(反映了破碎海冰平均尺寸的增加以及由于波能的衰减而导致单位面积区域内尺寸较大的破碎海冰所占比例的增加);分布维数D随着与开阔水距离增加而减小(说明了由于波能的衰减导致破碎海冰所受约束条件的减弱);形状参数γ随着与开阔水距离增加而减小(说明了随着波能的衰减破碎海冰尺寸分布范围的增大)。  相似文献   

森林沼泽景观区区域化探新、旧方法技术应用效果对比     

王会锋  彭立华  王晓云  安兴  陈恩科 《陕西地质》2007,25(2):44-53

自森林沼泽景观区1∶20万区域化探工作开展以来,各个单位、不同阶段工作方法技术各有不同,工作效果不明显。中国地质科学院地球物理地球化学勘查研究所近年来通过研究制定了新的工作方法技术,通过应用取得了较好的效果,为此本文仅以内蒙古一二五公里幅1∶20万区域化探新、旧方法技术的应用效果对比进行初步探讨。  相似文献   

声幅—变密度测井原理及测井解释方法     

李新胜  周俊乐 《陕西地质》2007,25(2):54-59

对利用声幅—变密度测井判断固井质量的测井原理和工作方式及资料的解释处理进行了介绍,并对固井中出现的各种可能曲线反映进行了详尽的分析,阐述了资料解释中不确定因素。  相似文献   

Synthesis,characterization of CdS/rectorite nanocomposites and its photocatalytic activity     

Jiangrong Xiao  Tianyou Peng  Dingning Ke  Ling Zan  Zhenghe Peng 《Physics and Chemistry of Minerals》2007,34(4):275-285

CdS/rectorite nanocomposite was synthesized via a cation-exchange reaction followed by a sulfurization process. The obtained samples were characterized by using X-ray diffraction (XRD), fourier transform infrared spectra (FTIR), transmission electron microscope (TEM), UV-Vis diffuse reflectance spectra (DRS), and thermal analysis. The measured results indicate that CdS species in the composites exist in the form of pillars and nanoparticles, the crystallized CdS particles are in the hexagonal symmetry. The photocatalytic activities of the pillared nanocomposite were enhanced significantly comparing with the bare rectorite and the pure CdS. Moreover, the photostabilities of the obtained nanocomposites are also better than that of the pure CdS due to the hosts retard the photocorrosion of the CdS.  相似文献   

Study of galvanic interactions between pyrite and chalcopyrite in a flowing system: implications for the environment     

Liu Qing You  Li Heping  Zhou Li 《Environmental Geology》2007,52(1):11-18

When galvanic interactions between pyrite and chalcopyrite occur in solution, pyrite, with the higher rest potential, acts as a cathode and is protected whereas chalcopyrite, with the lower rest potential, acts as an anode and its oxidation is increased. In this work a three-electrode system was used to investigate the corrosion current density and mixed potential of a galvanic cell comprising a pyrite cathode and a chalcopyrite anode in a flowing system. The results showed that with increasing concentration of ferric ion in the solution, with increasing acidity, and with increasing flow rate of the solution, the corrosion current density increased and the mixed potential of the galvanic cell became more positive. These experimental results are of direct significance to the control of environmental pollution in mining activity. By using the galvanic model, mixed potential theory, and the Butler–Volmer equation, the experimental results were explained theoretically.  相似文献   

Potential hyperaccumulation of Pb, Zn, Cu and Cd in endurant plants distributed in an old smeltery, northeast China   总被引：1，自引：0，他引：1  

Shuang Cui  Qixing Zhou  Lei Chao 《Environmental Geology》2007,51(6):1043-1048

The absorption and accumulation of Pb, Zn, Cu and Cd in some endurant weed plant species that survived in an old smeltery in Liaoning, China, were systematically investigated. Potential hyperaccumulative characteristics of these species were also discussed. The results showed that metal accumulation in plants differed with species, tissues and metals. Endurant weed plants growing in this contaminated site exhibited high metal adaptability. Both the metal exclusion and detoxification tolerance strategies were involved in the species studied. Seven species for Pb and four species for Cd were satisfied for the concentration time level standard for hyperaccumulator. Considering translocation factor (TF) values, one species for Pb, seven species for Zn, two species for Cu and five species for Cd possessed the characteristic of hyperaccumulator. Particularly, Abutilon theophrasti Medic, exhibited strong accumulative ability to four heavy metals. Although enrichment coefficients of all samples were lesser than 1 and the absolute concentrations didn’t reach the standard, species mentioned above were primarily believed to be potential hyperaccumulators.  相似文献   

Spheroidal oscillations of the Earth stimulated by the Sumatra-Andaman earthquake with CDSN data     

万永革盛书中  周公威郭燕平 尚丹 《地震学报(英文版)》2007,20(4):392-404

The 0S2~0S54 spheroidal modes of Earth’s free oscillations, triggered by the great Sumatra-Andaman earthquake of 26 December 2004 are retrieved from VHZ data recorded by seven upgraded stations of China Digital Seismograph Network (CDSN). We compare these spheroidal modes with theoretical free oscillation spectra calculated from the Preliminary Reference Earth Model (PREM) and find a coincidence between their periods. Spectral splitting phenomenon is observed obviously in 0S2, 0S3, 0S4, 2S1 and 1S2 free oscillation modes. What is most noticeable is that the oscillation mode 2S1 is reported for the second time (the first time by Rosat et al) without any data stacking. We simulated the split singlet of 0S2 mode on seven CDSN stations based on general focal mechanism and seismic moment of the earthquake. The result shows that seismic moment of the earthquake can reach 1023 N.m. We also find that the recording of Earth’s free oscillations carries abundant information of source mechanism and earthquake location, which is applicable to the detailed study of source rupture parameters.  相似文献   

The mean value concept in mono-linear regression of multi-variables and its application to trace studies in geosciences   总被引：1，自引：1，他引：1  

A J T JULL 《中国科学D辑(英文版)》2007,50(12):1828-1834

The "mean value concept" in a mono-linear regression of multi-variables is clarified.Its applications to reconstruction of the past 90-year salinity of the sea surface water in Xisha Islands and to tracing the past 80 ka paleo-geomagnetic events from the Luochuan loess 10Be record are introduced in detail,which show the significance and the potential of the "mean value concept" in geoscience research.  相似文献