亚洲沙尘暴的遥感监测方法研究 --以中国-日本合作研究区为例   总被引：4，自引：0，他引：4  

刘志丽  马建文  张国平  周自江 《武汉大学学报(信息科学版)》2005,30(8):708-711,F0003

介绍了亚洲沙尘暴遥感监测的一些新方法,并对监测结果与数据进行了综合分析,这些结果能够为GCM全球尺度沙尘模型提供参数和验证数据。本次研究结果为亚洲沙尘暴的中长期预测/预警系统提供了新的遥感技术方法。  相似文献   

Elemental particle size distributions. Measured and estimated dry deposition in Sfax region (Tunisia)     

M. Masmoudi  I. Belghith  M. Chaabane 《Atmospheric Research》2002,63(3-4)

Mass size distribution of the crustal elements (Al, Ca, Fe, Mg, Si, Ti), anthropogenic elements (Zn, Mn, Cr, Cu, K, P, Pb) and sea elements (Na, Cl) were obtained from measurements carried out with an inertial cascade impactor in Sfax. A fitting procedure by data inversion was applied to those data. This procedure yields accurate size distributions of aerosols in the diameter range 0.1–25 μm in two different sites. In a coastal industrial site, the mass distribution of the aerosol showed a bimodal structure; and in urban area, the lower particle mode cannot be observed. The elemental dry deposition flux was calculated as a function of particle size. The element flux size distribution increased rapidly with particle size. The modelling results indicate that the majority of the crustal and anthropogenic elements flux (>90%) was due to particles larger than 3 μm in diameter.  相似文献   

山东尚南断块古近系东营组沉积相及其古地理?          下载免费PDF全文

毕义泉 《古地理学报》2002,4(3):19-25

尚南断块位于山东省胜利油田东营凹陷尚店油田西南部。该区的古近系东营组顶底均为不整合面或沉积间断面，发育了较好的湖侵三角洲相沉积。基于100余口钻井、地震资料，70多张单井剖面柱状图编制及14条剖面的对比，进行了东营组精细沉积相研究，编制出30余幅沉积微相投点图和岩相古地理图。研究表明，东营 沉积时期气候潮湿、雨水丰沛、河流纵横、湖泊扩大、湖水变深等为处于斜坡地区的尚南地区发育湖侵期三角洲提供了良好的条件。控制该区沉积和地层发育的区域性物源来自埕宁隆起和鲁西隆起，但来自滨县凸起和林樊家突起的局部物源也有很大影响。东营期岩相古地理经历了早、中、晚期的演化，早期发育了以三角洲平原为主的沉积环境，中期形成了大范围的破坏性三角洲环境，晚期以前三角洲环境为特色。  相似文献   

中国沙尘暴天气的新特征及成因分析   总被引：65，自引：6，他引：65       下载免费PDF全文

张仁健  韩志伟  王明星  张小曳 《第四纪研究》2002,22(4):374-380

2000～2002年,中国北方地区频频发生沙尘暴天气,给当地和广大下游地区工农业生产、交通运输、空气质量和人民的日常生活都带来了极大危害。沙尘暴天气呈现频次高、发生时间提前、发生期时间长、强度大、影响范围广等新特征。对气候变化和地理环境背景的分析研究表明,近年来中国北方沙尘暴频繁爆发的原因主要是:1)近两年处于反厄尔尼诺(拉尼娜)事件的高峰期,使东亚冬季风频繁,导致大风天气频繁发生;2)在沙尘暴发生季节,中国北方降水明显减少,气温回升迅速且温度偏高于往年,使解冻的地表土层疏松,为沙尘暴的发生提供了丰富的沙源;3)近年来中国北方干旱加剧、土地荒漠化严重,使原本广阔的戈壁沙漠面积更加扩大,有利于沙尘暴天气的发生,这与不合理的土地利用状况有关。  相似文献   

老柞山金矿田鸡爪沟金矿床地质特征及成因探讨   总被引：1，自引：1，他引：1  

何宝林  赵海鹏 《矿产与地质》2002,16(3):165-167

分析了鸡爪沟金矿床地质特征和成因 ,并对形成过程进行理论推导 ,认为该矿床为与火山作用有关的中温岩浆热液充填型矿床。  相似文献   

动物体内青石棉纤维变化特征的显微研究   总被引：2，自引：0，他引：2  

董发勤  罗素琼  李国武 《矿物学报》2002,22(3):191-195

石棉纤维粉尘注入动物体内后，一部分形成石棉小体或石棉斑，一部分仍为裸露纤维。石棉小体内的纤维表面基团和组织内的某些蛋白反应可形成新的表面介体。粉尘在动物体内引起的动物病变主要是纤维化组织包裹和间皮瘤，机体以吞噬、包裹、缠绕，或以生化溶解方式排解粉尘。纤维自身则出现变短、尖部圆化、折断、分叉现象，也可以出现溶解、迁移、表面化学反应等。肺泡内纤维的碳酸盐化现象是体内纤维溶解和反应的新方式。动物体内间皮瘤可生长在注入部位也可在非注入部位，某种毒性衍生物质的生成和迁移是引起病变的主要原因。体内纤维粉尘的溶解是一个非常缓慢的过程，细小粉尘易于溶解和迁移。体内粉尘的膜阻滞现象在腹膜、胸膜上较为常见，在膜部位不易生成间皮瘤，肿瘤多引发在膜的内侧。但膜可以弱纤维化包裹。  相似文献   

Spatial variation of overbank aggradation rate and its influence on avulsion frequency   总被引：4，自引：0，他引：4  

Torbjörn E. Törnqvist  John S. Bridge† 《Sedimentology》2002,49(5):891-905

Abstract River avulsions are commonly considered to be driven by the aggradation and growth of alluvial ridges, and the associated increase in cross‐valley slope relative to either the down‐channel slope or the down‐valley slope (the latter is termed the slope ratio in the present paper). Therefore, spatial patterns of overbank aggradation rate over stratigraphically relevant time scales are critical in avulsion‐dominated models of alluvial architecture. Detailed evidence on centennial‐ to millennial‐scale floodplain deposition has, to date, been largely unavailable. New data on such long‐term overbank aggradation rates from the Rhine–Meuse and Mississippi deltas demonstrate that the rate of decrease of overbank deposition away from the channel belt is much larger than has been supposed hitherto, and can be similar to observations for single overbank floods. This leads to more rapid growth of alluvial ridges and more rapid increase in slope ratios, potentially resulting in increased avulsion frequencies. A revised input parameter for overbank aggradation rate was used in a three‐dimensional model of alluvial architecture to study its effect on avulsion frequency. Realistic patterns of avulsion and interavulsion periods (≈1000 years) were simulated with input data from the Holocene Rhine River, with avulsions occurring when the slope ratio is in the range 3–5. However, caution should be practised with respect to uncritical use of these numbers in different settings. Evidence from the two study areas suggests that the avulsion threshold cannot be represented by one single value, irrespective of whether critical slope ratios are used, as in the present study, or superelevation as has been proposed by other investigators.  相似文献   

Regional characteristics of dust events in China     

WANG Shigong  WANG Jinyan  ZHOU Zijiang  SHANG Kezheng  YANG Debao  ZHAO Zongsuo 《地理学报》2003,13(1):35-44

The regional characteristics of dust events in China has been mainly studied by using the data of dust storm, wind-blown sand and floating dust from 338 observation stations through China from 1954 to 2000. The results of this study are as follows: (1) In China, there are two high frequent areas of dust events, one is located in the area of Minfeng and Hotan in the South Xinjiang Basin, the other is situated in the area of Minqin and Jilantai in the Hexi Region. Furthermore, the spatial distributions of the various types of dust events are different. The dust storms mainly occur in the arid and semiarid areas covering the deserts and the areas undergoing desertification in northern China. Wind-blown sand and floating-dust not only occur in the areas where dust storms occur, but also extend to the neighboring areas. The range of wind-blown sand extends northeastward and southeastward, but floating-dust mainly extends southeastward to the low-latitude region such as the East China Plain and the area of the middle and lower reaches of the Yangtze River. Compared with wind-blown sand, the floating-dust seldom occurs in the high latitude areas such as North Xinjiang and Northeast China. (2) The affected areas of dust storms can be divided into seven sub-regions, that is, North Xinjiang Region, South Xinjiang Region, Hexi Region, Qaidam Basin Region, Hetao Region, Northeastern China Region and Qinghai-Xizang (Tibet) Region. The area of the most frequent occurrence of dust storms and floating-dust is in South Xinjiang Region, and of wind-blown sand in the Hexi Region. In general, the frequency of dust events in all the seven regions shows a decreasing tendency from 1954 to 2000, but there are certain differences between various dust events in different regions. The maximum interannual change and variance of dust events during this time happened in South Xinjiang Region and Hexi Region. The dust events generally occur most frequently in April in most parts of China. The spring occurred days of dust events occupied 60-70% of the whole year in Hetao Region and Northeastern China Region. However, in South Xinjiang Region and North Xinjiang Region, which was less affected by monsoon climate, dust events may occur at any time of the year, less than 50% of the events in this region occur during spring. In the remaining three regions 50-60% of the dust events occur in spring of a year.  相似文献   

陕西凤县八卦庙金矿床成矿地质特征及外围找矿前景分析   总被引：3，自引：0，他引：3  

张万业  刘方杰  黄长青 《矿产与地质》2003,17(2):136-139

阐述了八卦庙金矿床经历了长期、复杂的非线性成矿过程，着重分析了：含矿建造为与同生伸展断裂伴生的海底喷流热水沉积岩、热水浊积碎屑岩；脆-韧性剪切构造控制着主成矿过程；后期幔源岩浆气液叠加富集使其成为超大型金矿床。指出矿床成因为热水同生沉积细碎屑岩-剪切蚀变岩-幔源岩浆气液叠加富集型。八卦庙金矿床外围仍有巨大的找矿前景。  相似文献   

锡铁山铅锌矿地质特征、矿床成因及找矿标志   总被引：4，自引：1，他引：4  

李如满  汪树栋 《矿产与地质》2003,17(3):218-221

通过找矿工作的实践，认为锡铁山铅锌矿床是由火山喷流沉积—后期热液叠加改造富集的块状硫化物多金属矿床。区域上NW—SE向早古生代形成的裂谷带，三级盆地内沉积的晚奥陶世滩间山群的大理岩与绿片岩系是表区找矿的最佳区段。而绢云绿泥斜长片岩、含碳质绢云绿泥片岩、白色大理岩、条带状大理岩是铅锌矿的最重要的找矿标志。  相似文献