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71.
Evaluation of Fluorobenzoate Tracers in Surface Soils   总被引:2,自引:0,他引:2  
Dan B. Jaynes 《Ground water》1994,32(4):532-538
  相似文献   
72.
The Central Godavari delta is located along the Bay of Bengal Coast, Andhra Pradesh, India, and is drained by Pikaleru, Kunavaram and Vasalatippa drains. There is no groundwater pumping for agriculture as wells as for domestic purpose due to the brackish nature of the groundwater at shallow depths. The groundwater table depths vary from 0.8 to 3.4 m and in the Ravva Onshore wells, 4.5 to 13.3 m. Electrical Resistivity Tomography (ERT) surveys were carried out at several locations in the delta to delineate the aquifer geometry and to identify saline water aquifer zones. Groundwater samples collected and analyzed for major ions for assessing the saline water intrusion and to identify the salinity origin in the delta region. The results derived from ERT indicated low resistivity values in the area, which can be attributed to the existence of thick marine clays from ground surface to 12–15 m below ground level near the coast and high resistivity values are due to the presence of coarse sand with freshwater away from the coast. The resistivity values similar to saline water <0.01 Ω m is attributed to the mixing of the saline water along surface water drains. In the Ravva Onshore Terminal low resistivity values indicated up coning of saline water and mixing of saline water from Pikaleru drain. The SO 4 ?2 /Cl?and Na+2/Cl?ratios did not indicate saline water intrusion and the salinity is due to marine palaeosalinity, dilution of marine clays and dissolution of evaporites.  相似文献   
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Studies of three deposits of neo-Archean banded iron formations from the West Karelian domain (the Kostomuksha deposit) and from the Central Kola block (the Olenegorsk and Kirovogorsk deposits) showed a pronounced difference in the isotope compositions of Nd from quartz and magnetite–hematite interlayers. The less radiogenic Nd of iron-containing layers compared to that of the quartz component may be considered as an indication of the formation mechanism of the treated banded iron formations. Thus, silicon-containing layers are related to submarine volcanism and iron was supplied to the sedimentation zone from other sources.  相似文献   
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Studied is the relationship between the density of hydrological stations (HS) of the main state observation network on the rivers and the population density commonly used as an indicator of the territory development. Given is the minimal required number of HSs of the main network computed using the objectively substantiated method. The territorial distribution of HS density depending on the population density is analyzed on the basis of the data of 1992 with the number of HSs of the total network that can be taken as minimal required for the main network. For the first time obtained are the regional relations of these characteristics for the time moment when the spatial distribution of HS density was close to the year 1987 to the countrywide highest HS density for the whole observation period. Established is the relationship between the HS density and density of population aggregates.  相似文献   
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Intense research and refinement of the tools used in performance-based seismic engineering have been made, but the maturity and accuracy of these methods have not been adequately confirmed with actual data from the field. The gap between the assumed characteristics of actual building systems and their idealized counterparts used for analysis is wide. When the randomly distributed flaws in buildings as they exist in urban areas and the extreme variability of ground motion patterns combine, the conventional procedures used for pushover or dynamic response history analyses seem to fall short of reconciling the differences between calculated and observed damage. For emergency planning and loss modeling purposes, such discrepancies are factors that must be borne in mind. Two relevant examples are provided herein. These examples demonstrate that consensus-based analytical guidelines also require well-idealized building models that do not lend themselves to reasonably manageable representations from field data. As a corollary, loss modeling techniques, e.g., used for insurance purposes, must undergo further development and improvement.  相似文献   
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Photographic measurements of the colour distribution in the irregular galaxy M82 are presented and interpreted in terms of a model of that galaxy. Two alternative models are discussed. In the first the galaxy consists of a disc of highly reddened OB-stars, whose scattered light is also seen in the halo, and a bulge of less reddened A—F stars. The direction of the inclination of the system, as inferred from this model, is opposite to that of LYNDS and SANDAGE (1963). The alternative inclination (second model) may possibly be preserved if one assumes a central dust ellipsoid reemitting scattered light from a central source of OB stars. If the velocities of the line emitting material refer to scattering particles, an inward motion of them is more probable than an outward one, irrespectively of the model, and the (dust) halo of the galaxy is probably contracting.  相似文献   
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