Assessment of regional karstification degree and groundwater sensitivity to pollution using hydrograph analysis in the Velka Fatra Mountains, Slovakia     

Peter Malik 《Environmental Geology》2007,51(5):707-711

Hydrograph analyses of groundwater depletion process in the spring were used for estimation of karstification degree and groundwater sensitivity to pollution in the whole catchment area. Differences of individual depletion hydrographs enable assessment of the anticipated extent of absorption, attenuation and self-purification processes during the groundwater penetration through the rock environment between its infiltration and its outflow in the spring. The method was applied in the SW part of the Velka Fatra Mountains (Slovakia) “Tlsta” hydrogeological structure. In total, 209 individual recession curves from 20 gauged springs were analyzed. Depending on characteristic groundwater depletion hydrographs with independent sub-regimes, categories of groundwater sensitivity to pollution were defined. Finally, resulting sensitivities to pollution were linked to lithostratigraphical units in the area.  相似文献   

Parametric study on performance of bridge retrofitted by unseating prevention devices     

刘光晏  张国镇 《地震工程与工程振动(英文版)》2006,5(1):111-118

1 Introduction Structural retro?t techniques (Roberts, 2005), such as restrainers, concrete shear keys, steel jackets, CFRPshells, base isolators, or dampers have been widely studied and implemented in actual structures based on the experiences learned from past earthquakes. In the Chi-Chi earthquake (EERI, 2001), the damage to simply-supported PCI girder bridges provided a different view from which to examine the function of a rubber bearing system for simply- supported bridges (NCREE,…  相似文献   

Humid Little Ice Age in arid central Asia documented by Bosten Lake, Xinjiang, China   总被引：15，自引：0，他引：15  

J. A. Holmes 《中国科学D辑(英文版)》2006,49(12):1280-1290

Short sediment cores retrieved from Bosten Lake, the largest inland freshwater lake in China, were used to explore humidity and precipitation variations in arid central Asia during the past millennium. The chronology of the cores was established using 137Cs, 210Pb and AMS 14C dating re- sults. Multi-proxy high-resolution analysis, including pollen ratios of Artemisia and Chenopodiaceae (A/C), carbonate content and grain size, indicates that the climate during the past millennium can be divided into three stages: a dry climate between 1000―1500 AD, a humid climate during the Little Ice Age (LIA) (c. 1500―1900 AD), and a warm dry period after 1900 AD. On centennial timescales, the climate change in northwestern China during the past 1000 years is characterized by oscillations between warm-dry and cold-humid climate conditions. All the proxies changed significantly and indi- cate increased precipitation during the LIA, including increased pollen A/C ratios and pollen concen- trations, decreased carbonate content and increased grain size. The humid period during the LIA re- corded by the Bosten Lake sediments is representative of arid central Asia and is supported by nu- merous records from other sites. During the LIA, the water runoff into the Keriya River and Tarim River in the Tarim Basin increased, while the ice accumulation in the Guliya ice core increased. Additionally, the lake levels of the Aral and Caspian Sea also rose, while tree-ring analysis indicates that precipita- tion increased. We hypothesize that both the lower temperature within China and the negative anomalies of North Atlantic Oscillation (NAO) during this period may have contributed to the humid climate within this area during LIA.  相似文献   

土壤颜色——一个可靠的气候变化代用指标   总被引：3，自引：0，他引：3  

陈一萌  陈兴盛  宫辉力  魏明建  李小娟 《干旱区地理》2006,29(3):309-313

将研究剖面自上而下以2cm间隔采取的样品,烘干并研磨至小于45μm,此时,土壤的颜色将不再发生变化。将处理好的样品分别测土壤颜色指标亮度、红度和黄度,将测得的亮度、红度和黄度指标分MIS4、MIS3、MIS2和MIS14个阶段,通过与研究剖面的气候指标磁化率、粒度和CaCO_3在百年尺度、千年尺度上的对比分析,以及在万年尺度上与高纬格陵兰GRIP冰芯记录和反映全球冰量变化的SPECMAP曲线进行对比分析表明：土壤颜色指标作为气候变化的代用指标无论在百年尺度、千年尺度还是在万年尺度上均是可靠的,这种可靠性在末次冰期阶段表现得更为显著,这一结论是否适用于整个第四纪冰期间冰期旋回,尚需更多黄土剖面的研究事实来加以证明。  相似文献   

滚 滑 复 合 轴 承 研 究     

田红平  张福润  杨楚民 《探矿工程》2003,30(1):60-62

针对牙轮钻头的滑动轴承和滚动轴承在实际工作中所存在的问题，提出一种牙轮钻头滚滑复合轴承，对滚滑复合轴承结构进行有限元对比分析、模拟对比试验和钻头现场验证实验，表明滚滑复合轴承是一种较先进的创新性轴承。  相似文献   

机械卡盘设计中的计算误差分析与应用          下载免费PDF全文

陈宝杰  卜长根 《探矿工程》2003,30(3):30-32,34

通过对普通机构二维力因素影响的分析，利用修正公式计算求值，以修正单因素影响最大值计算所产生的误差。利用这一计算方法，对CD—3型钻机卡盘进行了计算，得到了正确的设计结果，说明用修正公式对多因素影响采用单因素影响最大值计算进行修正是可行的。  相似文献   

晋祠泉断流与地下水资源保护关系   总被引：4，自引：0，他引：4  

黄皓莉 《中国煤田地质》2003,15(2):26-28

通过对晋祠泉域岩溶地下水水文地质条件的分析,阐述了晋泉形成机理和断流原因,认为晋泉断流是多种因素的综合效应。说明地下水资源保护是一项系统工程,应采取统一的、科学的、多层次的全面管理,才能有效地保护有限的地下水资源,唤醒人们在进行经济建设的同时,要注意保护我们赖以生存的地球环境。  相似文献   

铅锌矿山开发导致的重金属在环境介质中的积累   总被引：35，自引：4，他引：35  

杨元根  刘丛强  张国平  吴攀  朱维晃 《矿物岩石地球化学通报》2003,22(4):305-309

以连续提取法和相关性分析研究了土法冶炼锌、铅锌和矿山开采导致的重金属在废渣及环境介质土壤、溪流沉积物中的积累，并分析了其环境危害性。结果显示，贵州赫章土法炼锌导致的重金属Pb、Zn、Cd在环境介质中的积累相当高。水城杉树林铅锌矿山开采引起的重金属积累则相对较低，但也明显高于背景值；土壤和沉积物中的铁矿物对重金属有强烈的固定作用。除残渣态外，Pb、Zn在土壤、炼锌废渣中主要呈铁锰氧化物结合态，沉积物中则为碳酸盐结合态。可交换态Pb、Zn含量变异较大，但在炼锌废渣、土壤中含量明显高于河流沉积物，暗示铅锌矿开发对土壤环境的潜在危害更大。  相似文献   

青藏高原东缘构造演化的SHRIMP锆石U-Pb年代学框架   总被引：6，自引：2，他引：4  

闫全人  王宗起  刘树文  石玉若  李秋根  闫臻  王涛  王建国  张德会  张宏远 《地质学报》2006,80(9):1285-1294

青藏高原东缘一直被普遍认为是一个吸收印度—欧亚大陆碰撞变形的调节带。本文所获得的最新SHRIMP锆石U-Pb测年结果显示:青藏高原东缘具有更加复杂的地质历史。测年结果表明,高原东缘最古老的前寒武纪结晶基底形成于古元古代(2401~1912Ma)。这一古老基底首先受到中元古代构造热事件(1361~1040Ma)的影响,随后受到新元古代与弧岩浆活动有关构造热事件(791~817Ma)的强烈改造。松潘—甘孜复理石杂岩的基底是亲洋壳型的,形成于晚新元古代的大陆裂解作用(681~655Ma)。高原东缘的前寒武纪微地块可能是由这次裂解作用从扬子或青藏地块拉裂出去形成的。这些微陆块先增生拼贴于东冈瓦纳大陆、然后又从中裂离,并最终卷入高原东缘的特提斯构造演化过程中。伴随东冈瓦纳大陆裂解,高原东缘古特提斯洋于石炭纪至二叠纪早期拉开(328~292Ma),经早中生代弧-陆碰撞作用闭合(224~213Ma)。中侏罗世这一地区发育显著的构造岩浆活动(175Ma),但其动力学背景仍不十分清楚。晚白垩世岩浆活动(97Ma)可能是印度板块初始俯冲阶段的产物。新生代岩浆作用(18Ma)与陆-陆碰导致的大规模走滑断层作用所引起的同熔作用有关。  相似文献   

SEM-EDX Characterisation of Tropospheric Aerosols in the Negev Desert (Israel)     

Sophie Sobanska  Cécile Coeur  Willy Maenhaut  Freddy Adams 《Journal of Atmospheric Chemistry》2003,44(3):299-322

Individual aerosol particles collected in the Negev desert in Israel during a summer and winter campaign in 1996–1997 were analysed by scanning electron microscopy with energy-dispersive X-ray analysis. Hierarchical cluster analysis was performed to interpret the data on the basis of particle diameter and composition. Eleven particle classes (groups) provided clues on sources and/or particle formation. The summer samples were enriched in sulphates and mineral dusts; the winter samples contained more sea salts, aged sea salts, and industrial particles. The fine size fraction below 1 m diameter was enriched in secondary particles and showed evidence of atmospheric processing. The secondary sulphate particles were mainly attributed to long-range transport. A regional conversion from calcite to calcium sulphate occurred during summer. Industrial particles originating from local pollution appeared during winter.  相似文献