Evaluation of a probabilistic approach to simulation of alkalinity and electrical conductivity at a river bank filtration site

In river bank filtration, impurities present in the river water travel with the bank filtrate towards the pumping well. During this passage, certain types of impurities, such as turbidity, total coliform, and so forth, may get attenuated; however, it is interesting to note that some of the instant raw river water quality parameters, such as alkalinity and electrical conductivity, increase after the passage of water through the porous medium. This occurs because water, when passing through the soil pores, absorbs many of the solutes that cause an increase in alkalinity and electrical conductivity. Measurements at a river bank filtration site for a year showed that alkalinity of 116–32 mg l^?1 in river water increased to 222.4–159.9 mg l^?1 in the river bank filtered water. Likewise, the electrical conductivity increased from 280–131 μS cm^?1 to 462–409.6 μS cm^?1. This study uses a probabilistic approach for investigating the variation of alkalinity and electrical conductivity of source water that varies with the natural logarithm of the concentration of influent water. The probabilistic approach has the potential of being used in simulating the variation of alkalinity and electrical conductivity in river bank filtrate. Copyright © 2011 John Wiley & Sons, Ltd.     

边界单元法在电法勘探中的应用

本文用加权剩余法导出点源二维地电断面的边界单元法积分方程。通过付氏反变换,可获得三维空间的电位。若干模型上正演计算结果与解析解完全一致。对实测的ρ_s曲线进行了地形攻正及选择法反演拟合,解释结果与实际地质断面符合得很好。     

Subsoil zoning of Mexico City using qualitative relationships between soil strength and electrical resistivity

Summary The seismic events occurring on 19 and 20 September 1985, whose epicentre was located in the coastal region of Michoacan, Mexico, produced tremendous damage in Mexico City. As a result of these losses the civil authorities of the city decided to study and evaluate the mechanical characteristics of the subsoil. To achieve this, it was necessary to drill several boreholes to obtain needed geophysical and geotechnical information. The geophysical method of electrical resistivity was the most appropriate to the research. This method enabled us to understand the structure and soil characteristics of the Mexican Valley.     

Transport properties of rocks from statistics and percolation

Two simplified microstructural models that account for permeability and conductivity of low-porosity rocks are compared. Both models result from statistics and percolation theory. The first model assumes that transport results from the connection of 1D objects or pipes; the second model assumes that transport results from the connection of 2D objects or cracks. In both cases, statistical methods permit calculation of permeability k and conductivity , which are dependent on three independent microvariables: average pipe (crack) length, average pipe radius (crack aperture), and average pipe (crack) spacing. The degree of connection is one aspect of percolation theory. Results show that use of the mathematical concept of percolation and use of the rock physics concept of tortuosity are equivalent. Percolation is used to discuss k and near the threshold where these parameters vanish. Relations between bulk parameters (permeability, conductivity, porosity) are calculated and discussed in terms of microvariables.     

南极长城站至莫斯科和伊尔库茨克路径上时延的测量与传播路径研究

本文介绍了利用在南极长城站接收来自ＲＷＭ（莫斯科）和ＲＩＤ（伊尔库茨克）台的授时信号的无线电波时延的测量方法，并依据１９９１年４月至１９９１年９月所测量的传播时延数据分析了电波传播路径。说明了沿长、短大圆路径的传播时段。判定存在着非大圆路径传播并阐明了关于非大圆路径传播的一些变化规律。对非大圆路径发生的条件进行了探讨     

南极中山站固体潮观测分析

中国南极中山站位于南极拉斯曼丘陵地区（λ＝７６°２２′Ｅ，φ＝６９°２２′Ｓ），１９９１年３月至１９９３年２月，用ＬａｃｏｓｔｅＥＴ型重力仪，在这个地区进行了为期近两年的观测，取得了６００多天的有效资料，经调和分析和流变模型、海潮负荷改正后得到：δｏ１＝１．２２５３±０．００３１，Δφｏ１＝０．７３°±０．１４°；δｍ２＝１．０７８５±０．００４５，Δφｍ２＝－３．５５°±０．２９°从资料分析的精度来看，观测资料是比较好的；但由于海潮负荷改正缺少附近海域的资料，会对最终结果造成较大的影响