排序方式: 共有171条查询结果,搜索用时 15 毫秒
61.
用北京地区20个气象观测站41年(1960~2000年)的年平均气温记录,研究了北京地区的大尺度气温变化及其热岛效应.结果认为,(1)北京地区气温的年际变化具有大尺度的特点,1981年是显著的跃变点,跃变点比跃变前北京地区气温增加了0.55℃,近40年的增温率为0.25℃/10年.(2)北京城市热岛效应具有典型性.1960~2000年北京城市热岛平均强度接近1℃.随着北京城市建设和城市化速度的加快,北京城市热岛强度也在明显地增加,近40年热岛强度的增温率为0.31℃/10年. 相似文献
62.
PAN AiJun WAN XiaoFang CHEN HangYu & GUO XiaoGang Ocean Dynamics Lab. Third Institute of Oceanography State Oceanic Administration Xiamen China 《中国科学:地球科学(英文版)》2010,(2)
Diurnal evolution of the barrier layer (BL) and its local feedback features in the central Taiwan Strait (119.2oE,24.3oN) during summertime monsoon are investigated using in situ moored observations conducted by the Yan-Ping 2 research vessel in late June 2005.During the initiation phase,for the non-solar radiation tends to be trapped in the upper mixed layer,whereas the solar radiation can penetrate deeply through the mixed layer approaching the thermocline,most heat is accumulated inside the BL inducing a... 相似文献
63.
YU JunBao LIU JingShuang SUN ZhiGao SUN WeiDong WANG JinDa WANG GuoPing & CHEN XiaoBing Key Lab of Coastal Envionment Processed Yantai Institute of Coastal Zone Research for Sustainable Development Chinese Academy of Sciences Yantai China Key Lab of Wetl Ecology Environment Northeast Institute of Geography Agricultural Ecology Changchun Key Laboratory of Isotope Geochronology Geochemistry Guangzhou Institute of Geo... 《中国科学:地球科学(英文版)》2010,(5)
Nitrous oxide (N2O) and methane (CH4) emissions were measured using a static chamber method in two adjacent plots of freshwater marsh predominated by Calamagrostis angustifolia, one is seasonal waterlogged (SW) and the other without surface water accumulation (NW), in Sanjiang Plain wetland (47°35′N, 133°31′E), northeast China, during 2002-2004. The diurnal and seasonal flux variations of both gases were significantly correlated with 5-cm-soil temperature. The NW marsh is a source of N2O and sink of CH4, wh... 相似文献
64.
65.
Compositions of Upper Mantle Fluids Beneath Eastern China: Implications for Mantle Evolution 总被引:2,自引:0,他引:2
ZHANG Mingjie WANG Xianbin LIU Gang ZHANG Tongwei BO WenruiInstitute of Geological Science Lanzhou University Lanzhou Gansu Key Lab of Gas-Geochemistry Lanzhou Institute of Geology CAS Lanzhou Gansu First Institute of Oceanography State Oceanic Administration Qingdao Shandong 《《地质学报》英文版》2004,78(1):125-130
The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in Iherzolite xenoliths collected from different locations in eastern China has been measured by the vacuum stepped-heating mass spectrometry. These xenoliths are hosted in alkali basalts and considered as residues of partial melting of the upper mantle, and may contain evidence of mantle evolution. The results show that various kinds of fluid inclusions in Iherzolite xenoliths have been released at distinct times, which could be related to different stages of mantle evolution. In general, primitive fluids of the upper mantle (PFUM) beneath eastern China are dominated by H2, CO2 and CO, and are characterized by high contents of H2 and reduced gases. The compositions of PFUM are highly variable and related to tectonic settings. CO, CO2 and H2 are the main components of the PFUM beneath cratons; the PFUM in the mantle enriched in potassic metasomatism in the northern part of northeastern China has a high content of H2, while CO2 a 相似文献
66.
Leaching Behavior of Fly Ashes from Power Plants 总被引:1,自引:0,他引:1
LIU Guijian GAO Lianfen ZHENG Liugen ZHANG Haoyuan PENG Zicheng School of Earth Space Science University of Science Technology of Chin Hefei Anhui Key Lab of Loess Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi''an Shaanxi 《《地质学报》英文版》2004,78(3):720-723
The Yanzhou mine district, located in southwestern Shandong Province, is about 1300 km2 with more than 8×109tons of proved coal reserves and there are 10 big power plants in this area. A large amount of coal ashes, which are regarded as waste materials, have been stockpiled in the area and have influenced the environment of the mine district. In this paper, analysis of fly ash samples from three power plants is carried out, the enrichment and concentration of trace elements, Pb, Zn, Cu and As, in coal ashes are analyzed, and petrological and mineralogical characteristics and chemical compositions of coal ashes are studied. The aim of this work is to provide basic scientific data for utilization of ashes and reduction of environmental pollutions. 相似文献
67.
Three-Dimensional Gravity Model Applied to Underwater Navigation 总被引:1,自引:0,他引:1
YAN Lei FENG Hao DENG Zhongliang GAO Zhengbing Beijing Key Lab of Spatial Information Integration Its Applications Institute of RS GIS Peking University Beijing Beijing University of Posts Telecommunications Beijing 《《地质学报》英文版》2004,78(3):838-842
At present, new integrated navigation, which usesthe location function of reference gravity anomaly map to control the errors of the inertial navigation system (INS), has been developed in marine navigation. It is named the gravity-aided INS. Both the INS and real-time computation of gravity anomalies need a 3-D marine normal gravity model. Conventionally, a reduction method applied in geophysical survey is directiy introduced to observed data processing. This reduction does not separate anomaly from normal gravity in the observed data, so errors cannot be avoided. The 3-D marine normal gravity model was derived from the J2 gravity model, and is suitable for the region whose depth is less than 1000 m. 相似文献
68.
海底热水活动与海相富有机质层形成的关系——以华北新元古界青白口系下马岭组为例 总被引:12,自引:2,他引:12
对华北新元古界青白口系下马岭组富有机质层段的常量元素、微量元素和有机质含量进行了系统分析,其基本特征是富有机质沉积层段的SiO2含量明显高于泥质岩中的含量,SiO2含量与TOC成正相关系,与TiO2含量成反比,Si/(Si Al Fe)比值与TOC成正相关关系;与海底热水流体活动有关的P、Cu、Zn、Co、Ni、V等元素含量明显富集,Ba/Sr比值远远大于1,且与TOC之间成正相关关系。在下马岭组剖面上,从Qb1x^3向上纹层~薄层状硅质岩夹层蹭多,有机质含量也开始急剧增高。地质地球化学特征表明,在下马岭组富有机质沉积层段形成时,盆地拉张沉降作用强烈,海底热水活动与之紧密相伴,而且海底热水流体活动是导致该富有机质沉积层段形成的主要原因。 相似文献
69.
海底玄武岩中斜长石研究及其岩石学意义 总被引:6,自引:1,他引:6
冲绳海槽海底玄武岩中存在着三种不同世代的斜长石 :斑晶、微晶和基质斜长石 ,它们的平均粒径分别为 10 0 μm±、13μm±和 2μm±。斑晶斜长石在结构上存在核部与边部之分 ,在成分上反映为 An值出现明显的两级“台阶”,即 An值在80~ 90间波动的核部“平台”和 An值在 60~ 70间波动的边部“平台”,边部“平台”的成分与微晶斜长石一致。斜长石的结晶温度显示 ,斑晶核部温度为 12 50℃± ,边部温度为 10 50℃± ,而基质斜长石的结晶温度在 950℃±。笔者认为斜长石的这些特征 ,基本反映了该玄武岩浆的活动过程 :斑晶斜长石的核部记录了源区特征 ,边部及微晶斜长石反映了岩浆房中活动的特征 ,基质斜长石则记录了岩浆喷出洋壳后的过程。 相似文献
70.
Erosion, sediment transportation and accumulation in rivers 总被引:8,自引:5,他引:3
N. I. ALEKSEEVSKIY K. M. BERKOVICH and R. S. CHALOV Prof. Head of the Hydrology Department Faculty of Geography Moscow State University Moscow Russia Prof. Leading researcher Lab. of Soil Erosion Fluvial Processes Faculty of Geography Moscow State University Moscow Russia Prof. Head of the Lab. of Soil Erosion Fluvial Processes Faculty of Geography Moscow State University Moscow Russia 《国际泥沙研究》2008,23(2):93-105
The present paper analyses the interrelation between erosion, sediment transportation and accumulation proposed by N. I. Makkaveyev (1908-1983) and its further development in modem studies of river channel processes in Russia. Spatio-temporal linkages between erosion and accumulation are defined considering channel processes at different scales - river longitudinal profile, channel morphological patterns, alluvial bedforms (bars, dunes) and individual sediment particles. Relations between river geomorphic activity, flow transportation capacity and sediment budgets are established (sediment input and output; channel bed erosion and sediment entrainment into flow - termination of sediment transport and its deposition). Channel planforms, floodplain segments separated by the latter and alluvial channel bedforms are shown to be geomorphic expressions of sediment transport process at different spatial and temporal scales. This paper is dedicated to the 100th anniversary of N. I. Makkaveyev, Professor of the Moscow State University, author of the book "River channel and erosion in its basin" (1955). That book is regarded in Russia as the pioneering work which initiated the complex hydrological and geographical studies of channel processes and laid a basis for the theory of unified fluvial erosion-accumulation process. 相似文献