ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01451.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTGround water from deep wells was sampled for the presence of heterotrophic bacteria. Over 500 bacteria were isolated from well‐water samples on a low‐nutrient medium (R2A). Gram‐negative, rod‐shaped, nonmotile bacteria predominated, and Acinetobacter spp. comprised 54% of the total number of isolates. Selected isolates were inoculated into unamended and carbon‐enriched well water, and growth was measured by acridine orange direct count (AODC). Carbon sources included glucose, acetate, pyruvate, and succinate in 100 μg carbon/liter and 1,000 μg carbon/liter concentrations. The isolates grew in unamended filtered well water within 24 hours, and growth of an Acinetobacter sp. was further stimulated (greater than two orders of magnitude within five days) in the carbon‐enrich

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01452.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTIn situ water‐quality measurements, with respect to various ion and dissolved solids concentrations, have been closely approximated using open‐hole borehole geophysical logs. Analyses have shown good correlation between water resistivity (Rw, as determined from the logs) and dominant ion concentrations sampled from a wide range of water quality in Tertiary carbonate and granular formations.Rwcan be accurately determined by cross‐plotting saturated formation resistivity (Ro), obtained from normal or lateral resistivity logs, against formation bulk porosity from neutron, density, or acoustic velocity logs. Plotting these data on Hingle Resistivity‐Porosity Cross Plot (RPCP) paper with the proper matrix cementation factor (m, commonly 1.4 for unconsolidated sands or 1.6 for noncompacted Tertiary carbonates), will yield a graphical solution for Rwbased upon the relationship Rw=φmRo. The graphical technique also provides information concerning water‐quality variations with depth, true matric resistivity, location of confining beds, and vertical changes in formation porosity.Once Rwhas been determined, other ion concentrations can be estimated based upon chemical analyses of water samples from adjacent wells tapping a similar type water mass (i.e., calcium‐bicarbonate, sodium‐chloride water, etc.). Total dissolved solids (TDS), chloride, sulfate, potassium, sodium, magnesium, and hardness (as CaCO3) concentrations have consistently shown a high corre

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01453.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTThe disappearance of aldicarb [2–methyl–2(methylthio) propionaldehyde 0‐(methylcarbamoyl) oxime] and its two toxic degradation products, aldicarb sulfoxide and aldicarb sulfone, were measured in laboratory studies using ground waters and subsoils collected from citrus groves in Indian River County, Florida, and incubated under controlled conditions which best represented the in situ environment. The half‐life times for the disappearance of aldicarb and its two oxidized sulfur derivatives in ground‐water‐saturated subsoils ranged from 10–26 days. Based on the degradation rates found in this study, hydrologic parameters obtained for Indian River County subsoils, and amounts of total toxic residue reported entering Florida ground waters, it was estimated that toxic residues in aldicarb‐contaminated ground waters in Indian River County would migrate only short distances (0.3–5.2 m) before conversion of toxic residues to nontoxic resi

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01454.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTOil and gas exploration and engineering studies in water‐covered areas routinely use continuous seismic profiling techniques to obtain subsurface geologic information. Such profiling also can be used effectively in hydrologic studies to define the geologic framework of aquifer systems, to locate hydrologic boundaries, and in some places, to interpret the lithologic character of aquifers and confining beds.High‐resolution continuous seismic profiling, through the use of nonexplosive sound sources, can be used to produce continuous records that require little data processing before hydrogeologic interpretation. High‐resolution tuned transducer, minisparker, Uniboom, and small airgun systems operating from small boats in shallow water are capable of transmitting energy that can penetrate up to a hundred meters of earth materials. The resulting analog records of the reflected seismic signal closely resemble geologic sections.Surveys on the Housatonic River in Connecticut and Massachusetts, and on the Connecticut River, in water from 1 to 10 meters deep, have defined the bedrock surface beneath 60 meters of stratified drift. Seismic‐reflection profiling also was used to determine the extent and thickness of recent lake‐bottom deposits in two Connecticut lakes.Surveys along 90 kilometers of river channels in the Sarasota‐port Charlotte, Florida, area defined in detail the stratigrapahy and continuity of the shall

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01455.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTA model to solve the inverse problem in ground water has been developed. The model consists of an unconstrained multivariable optimization algorithm and a ground‐water simulation model. The optimization algorithm is a modified version of Newton's second derivative method. It is a ground‐water‐specific algorithm and was found to be more efficient than other more general unconstrained optimization algorithms requiring first‐ and/or second‐order derivatives and those requiring no derivatives. The groundwater simulation model is based on a finite‐difference technique but it can be replaced easily by a finite‐element model. The results of an application of this model to a real aquifer are discussed in a companion paper titled “Inverse Problem in Ground Water: Mod

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01456.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTThe inverse model developed in the companion paper entitled, “Inverse Problem in Ground Water: Model Development,” has been applied to the Fairfax‐New Baltimore aquifer in the lower Great Miami River Valley, Ohio. The information obtained from U.S. Geological Survey maps showed four distinct zones of differing hydraulic conductivities in the aquifer. The initial guesses for the hydraulic conductivities were made subjectively. The values of storativity were also assigned subjectively. The inverse model converged within five iterations, and an excellent match with the historical data was obtained. A sensitivity analysis was made to determine the response of the model to various initial guesses for the hydraulic conductivity, various assigned values of storativity, and the number of zones. The sensitivity analysis showed that the calculated hydraulic conductivities were insensitive to initial guesses but sensitive to the assigned values of storativity and the number of zones. However, reasonable deviations in the assigned values were absorbed by the surrogate hydraulic conductivity and the model remained a good input‐outpu

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01457.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTField studies along the southeastern shore of Trout Lake, Wisconsin, documented the presence of downward hydraulic gradients in a known discharge area as well as an anomalous distribution of seepage to the lakebed which deviates significantly from the generally accepted dogma that ground‐water seepage rates decrease exponentially with distance from shore. A numerical ground‐water model facilitated identification of the hydrologic control, namely the presence of a unit of high hydraulic conductivity, that accounts for the anomalous data, and is important for understanding the dynamics of the flow system. Field data including seepage measurements, visual inspection of lakebed materials and springs, and information obtained during drilling, indicate that a lens of coarse‐grained material intersects the lake. However, the significance of the coarsegrained material was not fully appreciated until a ground‐water model was used to simulate the flow system. The model indicated that the presence of the coarse‐grained lens has a marked effect on the flow pattern in the nearshore area causing downward hydraulic gradients which divert ground water into the lens and cause the occurrence of a localized high‐seepage area offshore where the lens intersects the lake. The numerical model predicts the anomalous seepage distribution noted in the field and the downward hydraulic gradients demonstrating that numerical models are practical tools for interpreting field data and for use in hypothe

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01458.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTA parameter identification (PI) procedure is developed and implemented with the United States Geological Survey's Method of Characteristics (USGS‐MOC) model. The PI procedure can be used to estimate selected model parameters from limited observations by quadratic programming. The code combining the PI procedure and the USGS‐MOC model has been tested by two numerical examples from a hypothetical aquifer. The test results show that the proposed algorithm can identify transmissivity and dispersivity accurately under ideal situations. The effects of using a simple characterization of the aquifer on parameter estimation and model are shown. Because of the improved efficiency in model calibration, extended application to field conditions is encouraged. However, it is cautioned that the interested users should be aware of the difficulties in field applications of PI, and it is recommended that sound engineering and scientific judgements are always needed in the use of the proposed, or any other PI met

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01459.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTThis paper illustrates several interesting effects of aquifer stratification on the results of two‐well tracer tests by means of a simplified computer model. In the model, it is assumed that the aquifer is horizontal, confined, of constant thickness and porosity, and perfectly stratified in the vicinity of the test wells. The nonuniform advection pattern is taken into account in detail by the model, but the local hydrodynamic dispersion is completely neglected. This simplified model has been verified in part by comparisons with available analytical solutions valid for homogeneous aquifers and in part by comparisons with the results of a two‐well field experiment of Pickens and Grisak (1981a) which was performed in a locally stratified aquifer. The applications of the model to several field situations with assumed values of the relevant parameters show that the concentration versus time breakthrough curve measured at the withdrawal well during a standard two‐well test would be very sensitive to variations of the hydraulic conductivity in the vertical. Without the use of supplementary observation wells with isolated multilevel sampling points, the standard test would give little useful information about the hydraulic and dispersive characteristics of an aquifer. Factors such as the length of the tracer injection period, the use of recirculation and the physical size of the experiment all have a strong effect on the breakthrough curve measured at the withdrawal well, making the interpretation of field results difficult unless aquifer stratification is measured and properly taken into ac

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb01460.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY