和田河夏季流量对区域0℃层高度变化的响应     

王永莉 玉苏甫·阿布都拉马宏武  毛炜峄 《气候变化研究进展》2008,4(03):151-155

利用和田市气象站的0℃层高度,和田河上游乌鲁瓦提和同古孜洛克水文站的实测流量资料,以及NCEP/NCAR 500 hPa月平均温度资料,分析了和田河夏季流量的变化、同期流域内0℃层高度情况以及500 hPa温度的特征。结果显示：1961-2004年,和田河夏季流量、和田站0℃层高度均呈不显著的线性下降趋势,在1979年分别出现了由丰到枯、由高到低的突变。和田河夏季流量典型偏丰、偏枯年同期500 hPa温度距平场有显著差异。在年代际和年际尺度上,和田河夏季流量对流域内0℃层高度变化都有明显的响应。  相似文献   

县级气象综合业务工作平台本地化   总被引：1，自引：0，他引：1       下载免费PDF全文

孙宝利  朝柯  李亚廷  翟云佳 《气象与环境学报》2008,24(3):46-50

根据县级气象综合业务工作平台建设的需求,以县级气象综合业务工作平台为基础,从县级气象业务工作实际出发,利用Visual Basic 6.0程序语言编程,研制出辽宁省县级气象综合业务工作平台本地化软件,并投入县级气象综合业务应用。经业务运行表明,软件的开发和使用,达到了实时业务系统高效运行的目的,使县级气象业务向集约化方向发展。  相似文献   

Spatial variability of N₂O concentrations and of denitrification-related factors in the surficial groundwater of a catchment in Northern Germany     

C. von der Heide  J. Bttcher  M. Deurer  D. Weymann  R. Well  W.H.M. Duijnisveld 《Journal of Hydrology》2008,360(1-4):230-241

N₂O concentrations and denitrification-related factors (NO₃, SO₄, dissolved organic carbon (DOC) and CO₂) were investigated in the surface groundwater of a catchment in northern Germany, the Fuhrberger Feld Aquifer (FFA). We sampled 79 plots that were selected according to the three criteria of land use, historical land use conversion (1954–1995) and groundwater level. We sampled three sites within each plot. The sampling depth was 0.5 m below the groundwater surface.We found no indication for the occurrence of autotrophic denitrification in the surface groundwater. Heterotrophic denitrification was identified as the main process for N₂O accumulation. The variability of N₂O concentrations on the plot-scale was extremely high and was poorly explained by the three sampling criteria. Other denitrification-related variables such as NO₃, SO₄ and DOC were less variable. The selection criteria land use and groundwater level clearly influenced the order of magnitude of N₂O concentrations in the surface groundwater. Under arable land, high NO₃ concentrations resulted in high N₂O concentrations. The surface groundwater under forest and pasture was almost NO₃-free and had also very small N₂O concentrations. Plots where the distance from the soil surface to the groundwater surface was large (>1 m up to 3.4 m) showed higher N₂O concentrations in the surface groundwater than plots where the distance was small (<1 m). A larger distance from the soil surface to the groundwater leads to a longer residence time and more decomposition of DOC in the soil. Consequently the less bioavailable DOC could inhibit the efficiency of the heterotrophic denitrification in the groundwater, yielding more N₂O. Elevated organic carbon levels in plots with historic land use conversion (pasture to arable) were very stable and did not influence N₂O concentrations. The high within plot variability showed that an upscaling of N₂O from the plot-scale to the catchment-scale is possible as long as the groundwater level regime and the land use do not change.  相似文献   

Difference of mercury bioaccumulation in red mullets from the north-western Mediterranean and Black seas   总被引：1，自引：0，他引：1  

M. Harmelin-Vivien  D. Cossa  D. B?naru  C. Mellon-Duval 《Marine pollution bulletin》2009,58(5):679-321

The relationships between total mercury (Hg) concentration and stable nitrogen isotope ratio (δ¹⁵N) were evaluated in Mullus barbatus barbatus and M. surmuletus from the Mediterranean Sea and M. barbatus ponticus from the Black Sea. Mercury concentration in fish muscle was six times higher in the two Mediterranean species than in the Black Sea one for similar sized animals. A positive correlation between Hg concentration and δ¹⁵N occurred in all species. Increase in Hg concentration with δ¹⁵N was high and similar in the two Mediterranean fishes and much lower in the Black Sea species. Since this was neither related to trophic level difference between species nor to methylmercury (MeHg) concentration differences between the north-western Mediterranean and the Black Sea waters, we suggested that the higher primary production of the Black Sea induced a dilution of MeHg concentration at the base of the food webs.  相似文献   

The late Holocene mollusc fauna of the Aral Sea and its biogeographical and ecological interpretation     

Andrei Filippov 《Limnologica》2009,39(1):67-85

The Aral Sea, in 1960 the fourth largest lake on Earth, has since experienced a catastrophic environmental change, which appears to be mainly a result of human impact. Here, we attempt to add to a better understanding of environmental changes during the last millennium by using fossil mollusc assemblages obtained from 10 sediment cores, which were taken by gravity coring in 1991. The biogeographical analysis demonstrates that no endemic molluscs have existed in the Aral Sea during the last 1000 years. The investigated taxa are of Caspian and Palaearctic origin. The molluscan biodiversity is much lower than previously assumed and particularly low for such a large lake, indicating unstable ecological conditions during the period investigated. Using comparative ecological analyses of thanatocoenoses and stable isotope ratios in gastropod shells, we conclude that the main lake level changes of the last millennium were strong and abrupt, showing relative high stands at about 1300 AD and 1650 AD.  相似文献   

三峡井网井水位对汶川8.0级地震的同震响应特征研究h          下载免费PDF全文

刘成龙  王广才  张卫华  梅建昌 《地震学报》2009,31(2):188-194

系统分析了三峡井网8口井水位对汶川8.0级地震的同震响应及其后效特征,揭示出这些特征因井而异,其差异性在井孔结构相似的条件下主要取决于井点的构造部位、观测含水层的地下水埋藏类型、含水层的导水系数等条件;深入研究了井水位同震后效特征中残留阶升与阶降的力学含义及其地震预测意义,并用仙女山断裂带上近期地震活动验证了残留阶升区可能是未来地震危险区的科学推论．   相似文献   

Rainfall and Obtaining Information Regarding Earthquake Development Processes from Groundwater Level     

Li Yong  Fang Wei  Ma Li 《中国地震研究》2008,22(1):52-61

Many factors can cause changes of groundwater level, such as the development process of an earthquake, rainfall, solid earth tides etc. Among these we are interested in information regarding earthquake development processes. Eliminating the influence of various disturbance factors is an effective way to obtain seismic development process information contained in the groundwater level. This paper provides two different ways to remove the rainfall effect, and compares the two methods by means of correlation analysis. Furthermore, based on these a logistic regression model is established to describe the seismicity level.  相似文献   

Analysis on the Characteristics of the Coseismic Response of Water Levels Recorded in Three Wells in Hainan,China to the Two Sumatra-Andaman Strong Earthquakes     

Li Zhixiong  Gu Shenyi  Yuan Xiwen  Liu Wei  Ming Suihu  Yang Guang  Guo Nan 《中国地震研究》2008,22(4):448-459

The characteristics of seismic water level fluctuations of the two Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 on December 26,2004 and March 29, 2005 recorded at Jiaji well, Qionghai, Hainan were analyzed, the features of the infrequent ＂step＂ changes of well water level after the two earthquakes were also analyzed and the mechanism of the ＂step change＂ of well water level was discussed. Then the high-sample-rate digital observation data of seismically-induced water level fluctuations of the Sumatra-Andaman strong earthquakes with magnitude 8.7 and 8.5 recorded at Nanbin well, Sanya and Tanniu well, Wenchang were analyzed. The results suggest that the dominant period of the seismic well water level fluctuation in all three wells was comparatively accordant, the amplitudes of seismic water level fluctuation of the same earthquake in different wells were clearly different, the time duration of seismic water level fluctuations of different earthquakes at the same well was also clearly different.  相似文献   

密肋复合墙体的地震损伤极限概率分析     

田洁  姚谦峰  黄炜 《地震工程与工程振动》2008,28(4)

密肋复合墙体是密肋壁板结构体系的主要承载构件,本文根据32块密肋复合墙体在单调及低周往复循环荷载作用下的试验结果,结合我国现行规范的目标性能,提出了针对密肋复合墙体的三个损伤性能水平及相应的量化参数,研究了这种新型墙体的损伤模型及各性能水平的允许极限破坏指标的概率特性。结果表明,采用四种地震损伤模型计算的墙体屈服、极限、破坏状态的损伤指数,在给定的显著性水平下分别服从正态分布、对数正态分布或极值Ⅰ型分布,并得到了分布的统计参数,可为该类墙体基于损伤性能的可靠度分析提供依据和参考。  相似文献   

Glacial isostatic adjustment in 3-D earth models: Implications for the analysis of tide gauge records along the U.S. east coast     

Jonathan E. Davis  Konstantin Latychev  Jerry X. Mitrovica  Roblyn Kendall  Mark E. Tamisiea 《Journal of Geodynamics》2008,46(3-5):90

Tide gauge records of recent sea-level change along the U.S. east coast have received significant attention within the literature of glacial isostatic adjustment (GIA). Geographic trends in these tide gauge rates are not reduced by a GIA correction based on a commonly adopted radial viscosity profile (characterized, in particular, by a lower mantle viscosity 1−2×10²¹ Pa s), and this has led to speculation that the residual trends reflect contributions from neotectonics or oceanographic processes. While the trends can be significantly reduced by adopting an Earth model with a stiffer lower mantle, such a model appears to be incompatible with independent constraints from post-glacial decay times in Hudson Bay. We use a finite-element model of the GIA process to investigate whether 3-D viscosity variations superimposed onto the “common” radial viscosity profile may provide a route to reconciling the east coast sea-level trends. We find that the specific 3-D structure we impose has little impact on the geographic trends in the GIA-corrected rates. However, we do find that the imposed lateral variations in lower mantle viscosity introduce a nearly uniform upward shift of 0.5 mm/yr in GIA-induced sea-level rates along the U.S. east coast. Thus, inferences of regional (U.S. east coast) sea-level rise due to modern melting of ice reservoirs, based on tide gauge rates corrected using 1-D GIA models, may be significantly biased by this simplifying assumption.  相似文献