Relation of streams, lakes, and wetlands to groundwater flow systems   总被引：24，自引：10，他引：14  

Thomas C. Winter 《Hydrogeology Journal》1999,7(1):28-45

 Surface-water bodies are integral parts of groundwater flow systems. Groundwater interacts with surface water in nearly all landscapes, ranging from small streams, lakes, and wetlands in headwater areas to major river valleys and seacoasts. Although it generally is assumed that topographically high areas are groundwater recharge areas and topographically low areas are groundwater discharge areas, this is true primarily for regional flow systems. The superposition of local flow systems associated with surface-water bodies on this regional framework results in complex interactions between groundwater and surface water in all landscapes, regardless of regional topographic position. Hydrologic processes associated with the surface-water bodies themselves, such as seasonally high surface-water levels and evaporation and transpiration of groundwater from around the perimeter of surface-water bodies, are a major cause of the complex and seasonally dynamic groundwater flow fields associated with surface water. These processes have been documented at research sites in glacial, dune, coastal, mantled karst, and riverine terrains. Received, April 1998 · Revised, July 1998, August 1998 · Accepted, September 1998  相似文献   

Simulation of regional-scale groundwater flow in the Azul River basin, Buenos Aires Province, Argentina   总被引：5，自引：2，他引：3  

Marcelo R. Varni  Eduardo J. Usunoff 《Hydrogeology Journal》1999,7(2):180-187

  相似文献   

Yanshanian Magma-Tectonic-Metallogenic Belt in East China of Circum-Pacific Domain (Ⅰ):Igneous Rocks and Orogenic Processes     

Deng Jinfu　Mo Xuanxue　Zhao Hailing　LuoZhaohua　Zhao GuochunDepartment of Geology  Mineral Resources  China University of Geosciences  Beijing 《中国地质大学学报(英文版)》1999,10(1)

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云南地区波速比异常图像的南北差异   总被引：2，自引：0，他引：2       下载免费PDF全文

蔡静观  张喜玲  李永莉 《地震工程学报》1999,21(4):363-369

动态追踪了云南地区第4 强震活跃期6 .3 级以上强震前波速比异常图像,显示出明显的南北差异:滇西南的1988 年11 月6 日澜沧- 耿马7 .6 、7 . 2 级和1993 年1 月27 日普洱6 .3 级强震发生在低波速比异常区内; 中缅边境上的1992 年4 月23 日6 .7 、6 .8 级和1995 年7 月12 日孟连西7 .2 级强震发生在低波速比异常区边缘;而滇西北的1996 年2 月3 日丽江7 .0 级、1976 年11 月7 日、12 月14 日宁蒗6 .7 、6 .4 级和滇东的1995 年10 月24 日武定6 .5 级强震却都发生在高波速比异常区内.强震前近震震级 ML 与持续时间震级 MD 的震级差的南北差异也进一步证实了波速比异常的差别.  相似文献   

Structural and magnetic properties of Co2Al4Si5O18 and Mn2Al4Si5O18 cordierite     

K. Knorr  M. Meschke  B. Winkler 《Physics and Chemistry of Minerals》1999,26(6):521-529

The crystal structures, lattice dynamics and magnetic properties of synthetic Co-cordierite, Co₂Al₄Si₅O₁₈, and Mn-cordierite, Mn₂Al₄Si₅O₁₈ have been studied by neutron powder diffraction, infrared spectroscopy and magnetisation measurements. Due to different synthesis conditions, the Co-cordierite used here crystallised in the hexagonal α-cordierite structure with a disordered Si/Al distribution in the framework, while for the Mn-cordierite the orthorhombic β-structure has been determined. The experimentally determined paramagnetic moments, _exp (Mn) = 5.47(6) _B and _exp (Co) = 3.88(4) _B , are in good agreement with theoretical predictions for octahedrally coordinated Mn²⁺ and Co²⁺, respectively. In both compounds there is no magnetic long-range order down to at least 1.5 K. However, the onset of an anti-ferromagnetic short-range correlation of magnetic moments along [001] has been observed for Mn-cordierite by magnetisation and neutron diffraction measurements. This short-range magnetic correlation becomes evident from diffuse scattering observed at 2 K. The diffuse scattering has been interpreted in terms of a Blech-Averbach function. Received: 30 June 1998 / Revised, accepted: 3 March 1999  相似文献   

Microanalysis of Fe3+/ΣFe in oxide and silicate minerals by investigation of electron energy-loss near-edge structures (ELNES) at the Fe M 2,3 edge     

P. A. van Aken  V. J. Styrsa  B. Liebscher  A. B. Woodland  G. J. Redhammer 《Physics and Chemistry of Minerals》1999,26(7):584-590

The Fe M _2,3-edge spectra of solid solutions of garnets (almandine-skiagite Fe₃(Al_1–xFe_x)₂[SiO₄]₃ and andradite-skiagite (Fe_1–xCa_x)₃Fe₂[SiO₄]₃), pyroxenes (acmite-hedenbergite (Ca_1–xNa_x)(Fe²⁺ _1−xFe³⁺ _x)Si₂O₆), and spinels (magnetite-hercynite Fe(Al_1–xFe_x)₂O₄) have been measured using the technique of parallel electron energy-loss spectroscopy (EELS) conducted in a transmission electron microscope (TEM). The Fe M _2,3 electron energy-loss near-edge structures (ELNES) of the minerals exhibit a characteristic peak located at 4.2 eV and 2.2 eV for trivalent and divalent iron, respectively, prior to the main maximum at about 57 eV. The intensity and energy of the pre-edge feature varies depending on Fe³⁺/ΣFe. We demonstrate a new quantitative method to extract the ferrous/ferric ratio in minerals. A systematic relationship between Fe³⁺/ΣFe and the integral intensity ratio of the main maximum and the pre-edge peak of the Fe M _2,3 edge is observed. Since the partial cross sections of the Fe M _2,3 edges are some orders of magnitude higher than those of the Fe L _2,3 edges, the Fe M _2,3 edges are interesting for valence-specific imaging of Fe. The possibility of iron valence-specific imaging is illustrated by Fe M _2,3-ELNES investigations with high lateral resolution from a sample of ilmenite containing hematite exsolution lamellae that shows different edge shapes consistent with variations in the Fe³⁺/ΣFe ratio over distances on the order of 100 nm. Received: 14 April 1998 / Revised, accepted: 8 March 1999  相似文献   

Facies architecture of an isolated carbonate platform: tracing the cycles of the Latemàr (Middle Triassic, northern Italy)     

Sven O. Egenhoff  Arndt Peterhänsel  Thilo Bechstädt  Rainer Zühlke  & Jürgen Grötsch 《Sedimentology》1999,46(5):893-912

The 720-m-thick succession of the Middle Triassic Latemàr Massif (Dolomites, Italy) was used to reconstruct the lagoonal facies architecture of a small atoll-like carbonate platform. Facies analysis of the lagoonal sediments yields a bathymetric interpretation of the lateral facies variations, which reflect a syndepositional palaeorelief. Based on tracing of lagoonal flooding surfaces, the metre-scale shallowing-upward cycles are interpreted to be of allocyclic origin. Short-term sea-level changes led to subaerial exposure of wide parts of the marginal zone, resulting in the development of a tepee belt of varying width. Occasional emergence of the entire lagoon produced lagoon-wide decimetre-thick red exposure horizons. The supratidal tepee belt in the backreef area represented the zone of maximum elevation, which circumscribed the sub- to peritidal lagoonal interior during most of the platform's development. This tepee rim, the subtidal reef and a sub- to peritidal transition zone in between stabilized the platform margin. The asymmetric width of facies belts within individual metre-scale cycles was caused by redistribution processes that reflect palaeowinds and storm paths from the present-day south and west. The overall succession shows stratigraphic changes on a scale of tens of metres from a basal subtidal unit, overlain by three tepee-rich intervals, separated by tepee-poor units composed of subtidal to peritidal facies. This stacking pattern reflects two third-order sequences during the late Anisian to early middle Ladinian.  相似文献   

Global temperature and monsoon activity     

S. S. Dugam  S. B. Kakade 《Journal of Earth System Science》1999,108(4):305-307

In this paper an attempt has been made to search a new parameter for the prediction of the Indian summer monsoon rainfall. For this purpose the relationship of the global surface-air temperature of four standard seasons viz., Winter (December-January-February), Spring (March-April-May), Summer (June-July-August), Autumn (September-October-November) with the Indian summer monsoon rainfall has been carried out. The same analysis is also carried out with surface-air temperature anomalies within the tropical belt (30°S to 30°N) and Indian summer monsoon rainfall. For the present study data for 30 years period from 1958 to 1988 have been used. The analysis reveals that there is a strong inverse relationship between the monsoon activity and the tropical belt temperature.  相似文献   

矿物粉尘表面活性位及其变化分析   总被引：6，自引：3，他引：3  

董发勤  万朴  冯启明  宋功保  彭同江  李平  李国武 《岩石矿物学杂志》1999,18(3):264-272

本文通过酸碱蚀,强机械力和极性分子等表面作用,利用红外吸收光谱手段分析了７放物粉尘的表面基团裸露,转化过程,总结了矿物粉尘表面存在的基团类型及其表面活性位的分布及在不同环境条件下的转化,对讨论粉尘生物活性及矿物表面／细胞物理化学作用过程有重要意义。  相似文献   

Adhesion of foulings on surface energy of silicone rubber coatings     

Tian Jun  Xue Qunji 《海洋学报(英文版)》1999,18(1):97-102

INTRODUCTIONBiologicalfoulingonthehullsofshipsandothersubmergedmarinestructurescausesgreatha~s.Inadditiontodecreasingship'sspeed,andincreasingitsfuelconsumption,biologicalfoulingalsoincreasestheweightofnavigationalbuoys,interfereswithoperatingequipmentandsounddevices,clogsseawaterpipingsystems,adverselyaffectsheat-exchangerperformance,andpromotescorrosionofmetalsurface(HuangandCat,1984).UPtothepresent,antifoulingpaintshaveachievedtheireffectivenessbyreleasingattheirsurfacebiocides,allcom…  相似文献