ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00361.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTThis study investigated the biodegradation of benzene, toluene, and the isomers of xylene (BTX) in anaerobic batch microcosms containing shallow aquifer material. BTX loss occurred with the addition of either nitrate or oxygen. Denitrification was confirmed by nitrous oxide accumulation after acetylene blockage of nitrate reductase. When a limiting amount of nitrate was added, there was a corresponding limit to the loss of BTX and a limited amount of nitrous oxide production. We propose that the addition of nitrate to gasoline‐contaminated aquifers would serve as an adjunct to current remedial technique

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00362.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTThe presence, nature, and extent of perched zones are frequently important during investigation of potential waste disposal sites and contaminated sites. Often such zones are overlooked and cased off during drilling and completion of monitor wells. Typically large differences in water levels over short distances are the first indicator that perched conditions may exist at a site. Installation of piezometers can provide conclusive evidence of the presence, nature, and extent of perched zones, but such activity is costly and time‐consuming. Combined interpretation of the gamma‐gamma (GG) and neutron‐epithermal neutron (NN) geophysical well logs can assist in evaluating perched conditions and guide placement of additional piezometers in an effective and efficient manner. Subsequently, logs from the shallow portion of existing wells that are completed in deeper zones can be used to interpolate and extrapolate knowledge of perched conditions.Perched zones are often indicated on logs by an inverse response of the GG and NN logs at a higher elevation than a direct response of the same logs. Because interpretation of geophysical logs is nonunique, it cannot provide conclusive evidence as to whether a particular zone is saturated or unsaturated. Limitations on conditions that will result in a false response can be determined. When logs are used in conjunction with hydrologic and geologic information, they are a valuable tool for investigating zones of perched ground

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00363.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTTo help demonstrate the ability to operate a hazardous waste landfill with no escape of leachate, permeameter tests of the effects on clay liner material of leachates containing ppm levels of organics such as chloroform, methylene chloride, toluene, and chlorobenzene were run. To get an unambiguous future determination of a detection of failure by leachate leakage into the landfill underliner monitoring system, a single compound or agent was sought which could be used as a tracer material. Fluorobenzene was chosen because of its physicochemical properties and its uniqueness in the normal industrial waste stream.The leachate permeameter testing confirmed literature data indicating that dilute concentrations of organic solvents in landfill leachate do not impair the barrier properties of clay even after several pore volumes of throughput.The appropriateness of the choice of fluorobenzene was confirmed by examining its comparative migration and by looking for its effects on the clay. Modeling of permeameter solute effluent concentration data with the transport equation of Ogata (1970) has shown a reasonable fit. Retardations of the major components of the particular landfill leachate evaluated were as expected, with chlorobenzene>toluene>fluorobenzene = chloroform>methylene chloride. Fluorobenzene is a good representative of the least retarded chemicals. There were no adverse effects on the clay's barrier properties from the ppm level of fluorobenzene added to the leachate.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00364.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTTwo unlined ponds were used for holding and evaporation of brines produced with oil and gas at a well site in north‐central North Dakota. The brine‐evaporation ponds were in use from 1959 up to the late 1970s when they were backfilled and leveled. Continued salt‐water migration at this site since closure has decreased crop yields in surrounding fields and has killed trees in a shelterbelt within an area of approximately 10 acres.An apparent resistivity survey delineated a 360,000‐ft2 area of extremely low resistivity. Isoconcentration maps indicate that a highly saline leachate plume extends laterally in a 500‐foot radius around the ponds and vertically to a depth of 70 feet below the surface.Ground‐water recharge at this site is low because of the semiarid climate and the low hydraulic conductivity of the near‐surface sediments and, as a result, very little flushing of the brine from the sediment beneath the ponds has occurred. Pore water within the unsaturated zone beneath the reclaimed ponds contains essentially the same ionic concentrations as that: of brine impounded in these pits 10 to 25 years ago.Based upon the results of this research, we estimate that brine leachate will continue to migrate at slow rates from this site for tens and possibly hundreds of years if no action is taken. The construction of a mound over the site and/or an infiltration gallery around the perimeter would minimize the spread of brine and make it possible to return this land to production in the fores

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00365.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTPorous asphalt pavement is a storm‐water management technique which reduces runoff and enhances ground‐water recharge. Planned applications of this, or other ground‐water recharge techniques, require that ground‐water response to induced recharge be quantified. Here, we emphasize determination of the aquifer parameters hydraulic conductivity (K) and specific yield (Sy) at a porous asphalt ground‐water recharge facility installed near Willow Grove, Pennsylvania.We compare values of these aquifer properties derived from conventional laboratory and field techniques to those derived using recharge event data collected at the site. By the comparisons, we illustrate the techniques of aquifer property determination apropos to the design of ground‐water recharge installations. Because of the fractured nature of the aquifer, the K‐values determined from pumping test and slug test analyses are about an order of magnitude greater than those of rock core samples, while the field‐based specific yield values are about an order of magnitude less than effective porosities of the rock cores. Ratios of K/Sy derived from a chemical tracer test agree with the pumping test values. Finally, the K and Sy necessary to simulate facility response to recharge using a numerical model of ground‐water flow correspond to those derived from field‐oriented techniques rather than those of the rock cores.The results show that the design parameters K and Sy should be obtained from field‐based techniques, such as the nonsteady pump test, which match the time and space scale in which the facility is expected

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00366.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTA new simple and quick geophysical method for the siting of boreholes for hand‐pump supply in the crystalline rocks of Kano State, Nigeria has been developed. A single electromagnetic traverse with at least two depths of investigation is used to locate a potential subsurface feature which is then assessed by a vertical electrical sounding. Ground‐water quality has a significant influence on the data. The method and criteria for selecting a site are described in detail because careful site selection is important in reducing the time and money spent on unproductive drilling. In spite of generally unfavorable hydrogeological conditions in the crystalline rocks, 364 boreholes had acceptable rates of ground‐water production out of 429 sited using this m

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00367.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTThe mobility of a model macromolecule, blue dextran, was compared under laboratory conditions to the mobility of tritiated water through a sandy soil. The blue dextran eluted from the soil prior to the tritiated water. The phenomenon was compared to exclusion chromatography where molecules are separated by size with the largest eluting first and each molecule flowing through a different portion of the total porosity. The porosity occupied by the macromolecule was 0.87 times the porosity occupied by water. When the soil was amended with a mixture of kaolinite and bentonite clay in a 1:1 ratio to weight fractions of 2% and 6% total clay, the porosity occupied by the macromolecule was decreased to 0.81 and 0.66 times the porosity occupied by water, respectively. The implications to hydrophobic chemical transport based on the presence and mobility of a macromolecule were evaluated from a theoretical basis. Macromolecules should increase the relative mobility of slightly mobile compounds more than they increase the relative mobility of highly mobile compounds. Very hydrophobic compounds should show greater mobility under natural conditions than predicted, ignoring the presence of dissolved organic carbon.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00368.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTThe hydrodynamic dispersion stream function (HDSF) concept has been applied to contaminant plume analysis in aquifers. First, the governing equations for the HDSF are summarized both for uniform and nonuniform seepage velocity fields. Application of the methodology is shown with the HDSF developed for a strip contaminant source in a uniform seepage velocity field under steady‐state water flow and solute transport conditions in aquifers. With this solution, it is shown how to determine the hydrodynamic dispersion stream lines (HDSLs) and the hydrodynamic dispersion bounding stream lines (HDBSLs) for a given uniform ground‐water flow field. Applications of the methodology are shown for saturated and unsaturated zones under some idealized conditions. The results of the model may be used for the specification of the boundaries of a contaminant plume and the path lines of contaminant particles under equilibrium conditi

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00369.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTMany previous attempts have been made to establish an empirical relation between the electrical and hydraulic properties of aquifers. However, only regression models between transmissivity or permeability and a few electrical parameters have been used on the basis of the available pairs of data. Kriging, a geostatistical technique, estimates a regionalized variable at any point in space, and multivariate geostatistical techniques allow one to use several variables together to estimate any ‘spatial parameter. One such method, cokriging, is used to estimate the transmissivity based not only on measurements of transmissivity, but also on measurements of specific capacity and electrical transverse resistance. The studied aquifer is situated in the Medjerda Valley in Tunisia where very few data on transmissivity and specific capacity are available, but resistivity data are relatively abundant. It is shown that with the geostatistical technique, one can: (1) use several electrical or elastic properties, which are easily measured, in the estimation of the desired parameter without establishing any empirical relation; and (2) make the estimation at any point where none of these properties has been sampled and, at the same time obtain a variance of the estimation error. The method is also compared with the usual regression metho

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00370.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY