西藏蛇绿岩中二种合金矿物新变种   总被引：5，自引：0，他引：5  

白文吉  施倪承  杨经绥  方青松  代明泉  熊明  颜秉刚 《矿物学报》2002,22(3):201-206

在西藏雅鲁藏布江蛇绿岩带的东部，距拉萨200km的泽当罗莎蛇绿岩的铬铁矿中，发现有种类繁多的合金矿物，铬铁镍矿和依铁镍矿就是其中二种。铬铁镍矿分子式：Ni0.41Fe0.35Cr0.24，为等轴晶系，空间群为Fm3m，晶胞参数a=0.35622(2)nm。铱铁镍矿分子式：Ni0.66Fe0.18Ir0.16，属等轴晶系，空间群Oh^5-Fm3m，晶胞参数a=0.46486(4)mm。  相似文献   

Dissolved and particulate trace metals and their partitioning in a hypoxic estuary: The Tanshui Estuary in Northern Taiwan   总被引：1，自引：0，他引：1  

Tien-Hsi Fang  Che-Liang Lin 《Estuaries and Coasts》2002,25(4):598-607

The distribution and partitioning of trace metals (Co, Cu, Fe, Mn, Ni, and Zn) between dissolved and particulate phases were studied in the Tanshui Estuary. The upper reach of the estuary is hypoxic and heavily polluted due to domestic and industrial discharges. The concentration ranges of dissolved and leachable particulate trace metals in the Tanshui Estuary were: Co: 0.3–6.1 nM, 1.8–18.6 mg kg⁻¹; Cu: 5–53 nM, 22–500 mg kg⁻¹; Fe: 388–3,364 nM, 1.08–6.67%; Mn: 57–2,914 nM, 209–1,169 mg kg⁻¹; Ni: 7–310 nM, 6–108 mg kg⁻¹; and Zn: 12–176 nM, 62–1,316 mg kg⁻¹; respectively. The dissolved concentrations of the metals were 2–35 times higher than the average values of the world river water. The distributions of dissolved and particulate studied metals, except Mn, in the estuary showed scattering, which could be attributed to the discharges from many industrial wastewater disposal works located in the upper tributaries. The daily input of dissolved metals from the disposal works to the Tanshui Estuary ranged from 0.1–0.4 tons. Dissolved Mn was nearly conservative in the region with salinity higher than 10 psu, while particulate Mn decreased in the region with salinity of 10–15 psu. The concentration increased significantly seawards, corresponding with the distribution of dissolved oxygen. The distribution coefficient (K_D) for Mn in the lower estuary was nearly three orders of magnitude higher than in the upper estuary. This phenomenon may be attributed to the diffusion of Mn from the anoxic sediment in the upper estuary and gradual oxidation into particulate Mn in the middle and lower estuary as the estuarine water became more oxygenated. The distribution coefficient for Cu decreased with increasing salinity. The percentages of trace metals bound by suspended particulate matter decreased in the following order: Fe>Zn, Cu>Co>Mn>Ni.  相似文献   

昆仑山口西8.1级地震在四川地区的前兆异常效应   总被引：2，自引：0，他引：2  

程式  杜方 《四川地震》2002,(4):7-13

对昆仑口西8.1级地震发生前后四川地区地震前兆监测台网的测值曲线进行了系统的清理，发现存在有明显的孕震效应和震时效应，异常效应的幅度很大，容易鉴别，这对人类认识特大地震的影响场很有意义。  相似文献   

西北地区生态环境现状和演化规律研究   总被引：20，自引：25，他引：20  

唐克旺  王研  王芳  陈子丹 《干旱区地理》2002,25(2):132-138

利用20世纪70年代和90年代两个时段西北内陆地区的土地利用资料和遥感信息，对西北内陆地区的生态环境景观的20年的变化趋势进行了评价。通过评价，定量分析了西北内陆地区生态环境的总体变化趋势，研究了人工绿洲和天然绿洲的平衡比例关系以及与生态环境总体稳定的内在关系。这项研究对研究和确定生态环境保护合理阈值，维持绿洲稳定，保障当地社会经济的长远发展具有重要意义。  相似文献   

Velocity profile of a sand cloud blowing over a gravel surface   总被引：2，自引：0，他引：2  

Zhibao Dong  Hongtao Wang  Xiaoping Liu  Fang Li  Aiguo Zhao 《Geomorphology》2002,45(3-4)

Particle dynamic analyzer (PDA) measurement technology was used to study the turbulent characteristics and the variation with height of the mean horizontal (in the downwind direction) and vertical (in the upward direction) particle velocity of a sand cloud blowing over a gravel surface. The results show that the mean horizontal particle velocity of the cloud increases with height, while the mean vertical velocity decreases with height. The variation of the mean horizontal velocity with height is, to some extent, similar to the wind profile that increases logarithmically with height in the turbulent boundary layer. The variation of the mean vertical velocity with height is much more complex than that of the mean horizontal velocity. The increase of the resultant mean velocity with height can be expressed by a modified power function. Particle turbulence in the downwind direction decreases with height, while that in the vertical direction is complex. For fine sands (0.2–0.3 mm and 0.3–0.4 mm), there is a tendency for the particle turbulence to increase with height. In the very near-surface layer (<4 mm), the movement of blown sand particles is very complex due to the rebound of particles on the bed and the interparticle collisions in the air. Wind starts to accelerate particle movement about 4 mm from the surface. The initial rebound on the bed and the interparticle collisions in the air have a profound effect on particle movement below that height, where particle concentration is very high and wind velocity is very low.  相似文献   

矿山环境地质问题综合评价指标体系   总被引：28，自引：1，他引：28  

徐友宁  袁汉春何芳陈社斌  张江华 《地质通报》2003,22(10):829-832

本指标体系把矿山环境地质问题归为三大类23项指标，提出以指标指数作为划分环境地质问题危害程度等级的依据，给出2类指标评价指数的计算方法，以及各指标相应的权重。在此基础上，用模糊数学综合评判法评定矿山环境地质问题的历史、现状及其发展趋势的影响程度。在考虑矿山区位条件和恢复治理难度的基础上，最终给出矿山环境地质问题的综合评价等级，该等级也同时反映了矿山地质环境恢复治理的优先顺序。  相似文献   

末次冰期东亚季风气候的变迁：贵州都匀七星洞石笋的δ18O记录   总被引：4，自引：8，他引：4  

覃嘉铭  林玉石  张美良  王华  冯玉梅  涂林玲 《中国岩溶》2003,22(3):167-173

通过对贵州都匀七星洞4根石笋系统的31件TIMS U系及543件稳定同位素分析，揭示出其气候变化记录时限范围为1．1～8．5万a，相当于海洋同位素阶段的MIS2，MIS3，MIS4及MIS5a。根据δ^18O的变化可以准确确定它们之间的界线，其年龄值为：MISl／MIS2 11．3kaB．P．，MIS2／MIS3 28．7kaB．P．，MIS3／MIS4 59．6kaB．P．，MIS4／MIS5a 78．5kaB．P．。研究表明，末次冰期相当于格陵兰冰芯记录、北大西洋沉积记录的YD、Heinrich事件等的气候跃变事件，几根石笋取得了非常一致的准确定位及定年。其中YD事件发生于12．76～11．52kaB．P．，Heinrich事件的H1～H6分别为15～17kaB．P．，24．6kaB．P．，30．5kaB．P．，39．3kaB．P．，46．8～47．8kaB．P．以及60．4kaB．P．。在MIS4阶段，石笋记录于66．4kaB．P．及73．8kaB．P．揭示了两次冷事件，也可于格陵兰冰芯记录中找到相对应的冷谷。通过与GISP2的对比研究，表明东亚季风气候的百年至千年尺度的气候演变，与北大西洋及格陵兰高纬度地区的气候变化具有非常协调的对应关系。它对研究季风气候的动力机制及其与全球变化的响应关系具有特别重要的意义。  相似文献   

平原河网区域来水组成原理   总被引：1，自引：0，他引：1  

朱琰  陈方  程文辉 《水文》2003,23(2):21-24

对于一般树状分布河网，上一级河道总是汇入至下一级河道，位于河道下游断面的流量总是由其上游汇集而至。但对于平原河网地区，特别是人工控制建筑物众多，又受潮汐影响的地区(如太湖流域)，河网错综复杂，水流方向不定，要跟踪某个断面的水流去向，或某个河段的水体、断面流量是从哪里汇集而来的，非常困难。但这样的问题在生产实践中往往对其很感兴趣。例如从常熟枢纽引长江水流进入望虞河后，流向何处?河网各断面流量中或各河段水体中常熟枢纽引江水量占多少比重?对这些问题的研究可以估计常熟枢纽引江的效果和影响范围。因此，平原河网区域来水组成方法在生产实践中具有重要意义。重点介绍了平原河网区域来水组成原理及其在太湖流域的应用。  相似文献   

数字化气氡观测干扰因素的分析研究   总被引：1，自引：0，他引：1       下载免费PDF全文

张朝明  陈华静  朱方保  李罡风  陶月潮  罗志春  束克明 《地震地质》2003,25(4):640-646

在进行地下流体数字化气氡观测及将观测资料应用于震情分析的过程中 ,发现某些干扰因素对数字化气氡观测和水氡的影响不同。在目前所用观测仪器和方法的条件下 ,气温对气氡值的影响系数为 - 0 4 % /℃ ;气压对气氡测值的影响系数为 0 1% /hPa ;不同类型的气水分离装置对气氡观测的影响很显著 ;同一含水层的井 (泉 )出水量的短期变化可引起观测水井流量的变化 ,但对气氡测值影响不显著 ;气氡测值对逸出气流量的变化反映不明显 ;逸出气含有杂质及气路泄漏等均会引起测值的下降。结合仪器的工作原理 ,对干扰产生的机制以及排除的方法进行了讨论  相似文献   

Principle and mathematical method for inverting stress State of a medium from the remote sensing data     

尹京苑  邓明德  钱家栋  房宗绯  赵宝宗  刘晓琳 《地震学报(英文版)》2003,16(4):413-421

It has been proved through experiments that the electromagnetic radiation energy of a substance will vary when stress acts on the substance. This moment, the electromagnetic radiation energy (observation value) received by the remote sensor is triggered not only by the substance temperature and also by the stress. Separating quantitatively these two kinds of electromagnetic radiation energy and then inversing the actual temperature state and stress state of a medium is a matter with practical significance in earthquake prediction and stability monitoring for the large-scale geotechnical engineering. In this paper the principle and the mathematical method for inversing stress by using multiband remote sensing data are discussed in detail. A calculation example is listed.  相似文献