bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tracing Ground‐Water Movement in Abandoned Coal Mined Aquifers Using Fluorescent Dyes
Authors: Aldousa P. J. , Smartb P. L. 
Published: March 2006

ABSTRACTIn shallow, essentially free‐draining abandoned coal mine workings, quantitative ground‐water tracing using the orange fluorescent dye Sulpho Rhodamine B (CI 45100) provides a powerful hydrogeological tool for determining ground‐water flow regimes. However, this is not the case in deep, confined, abandoned coal mine workings where various dyes exhibit a nonconservative behavior due to adsorption onto ferric hydroxide deposits. This is a more significant problem than that of the effects of pH or acidity on fluorescence. Laboratory tests indicate that dyes with sulphonic functional groups should be selected in such situations and that dye concentrations need to be maintained at the highest level commensurate with aesthetic and toxicological conditions.
Electromagnetic Mapping of Fresh‐Water Lenses on Small Oceanic Islands
Authors: Stewart Mark 
Published: March 2006

ABSTRACTMany small oceanic islands have fresh‐water lenses that can be used for domestic water supplies or dry season augmentation for rainfall catchment systems. However, these small lenses are often irregular in extent and thickness. Some islands have several small, isolated lenses. By making a few reasonable assumptions, the electromagnetic (EM) profiling method can be used to estimate lens thickness. If it can be assumed that the water table is close to sea level, and that the unsaturated and fresh‐water saturated geologic units have low bulk conductivities, the interface depth can be obtained from a three‐layer solution. The first layer is the unsaturated zone. Its thickness is assumed to be the land surface elevation above sea level. The third layer is the salt‐water saturated zone; it is assumed to be infinitely thick. The layer conductivities are either estimated or obtained from DC resistivity soundings. In resistive environments only the third‐layer conductivity has a significant effect on the calculated interface depth. The only remaining unknown is the second‐layer thickness, which represents the fresh‐water saturated zone. The second‐layer thickness is sensitive to the value used for the third‐layer conductivity. Calibration of the EM‐derived interface depth with other geophysical or water‐quality data is recommended, unless relative lens thicknesses are sufficient to meet the survey objectives. Application of this method to field studies of a sandy barrier island and a carbonate key, both in Florida, has provided useful data which correlate well with other geophysical and water‐quality data.
WATEQB – BASICA REVISION OF WATEQF FOR IBM PERSONAL COMPUTERS
Authors: Arikan Alparslan 
Published: March 2006

Abstract. WATEQB is a BASICA revision for IBM PC of WATEQF, a geochemical model for chemical equilibrium and saturation of natural waters. This model computes the speciation of inorganic ions and complex species in solution for a given water analysis.WATEQB is identical to the FORTRAN IV version from the standpoint of chemical process; however, the structure of the program differs from the original version. The structure of the program is not complex and allows the user to try some new modifications, if necessary.Due to the limited memory of personal computers and in contrast to the large volume of the original version of the program, the author has created four data files, one of which is of random access type. Reading the thermochemical data is possible through these four data files.This paper demonstrates how to set up the input data to execute WATEQB and describes the program rather than the model. The users of WATEQB will increase as personal computers become more common.
The Victoria Province Drought Relief Project, I. Geophysical Siting of Boreholes
Authors: White C. C. , Houston J.F.T. , Barker R. D. 
Published: March 2006

ABSTRACTAs a result of the recent drought in central Africa, an accelerated well drilling program was commissioned in Victoria Province, Zimbabwe, to help alleviate the shortage of water.An analysis of the data collected during the siting of these boreholes showed that geophysical techniques can be used reliably to determine regolith thickness and provide an indication of regolith lithology. Valleys and the zone of deep weathering around bornhardts were found to have the greatest potential for water‐supply boreholes. The relationship between regolith resistivity and specific capacity is masked by the clay mineralogy of the regolith which must be taken into account when siting boreholes. Despite this effect, optimum values of regolith resistivity for production boreholes in Victoria Province were established which may be of value in similar Basement terrain elsewhere.
Influence of Outlying Observations on Selected Estimates of Parameters of Distributions
Authors: Rajagopal R. 
Published: March 2006

ABSTRACTMost measures of ground‐water quality are positively skewed with a few observations occurring with significantly large values. Using a set of mathematical expressions and readily available software, the effect of deleting one or more large‐valued observation(s) on selected estimates of parameters of underlying distributions are evaluated. The effect of deleting a single large‐valued observation on the mean is linear, and on the standard deviation it is nonlinear (approximately quadratic). In the case of multiple deletions, the effect of sum of the large‐valued observations on the mean is linear and on the standard deviation it is nonlinear. The effect on the standard deviation is a function of the sum of squares of deleted observations. The standard deviation is much more sensitive to the magnitude of deleted observations than the mean. Analysis of a large data set consisting of 17 primary and secondary drinking‐water constituents showed that (with a few exceptions) the effect of deleting large‐valued observations on the standard deviation is considerably higher than that on the mean, the 95th and the 99th percentiles. Seldom are percentiles below the 75th affected by the deletion of large‐valued observations. Analyses of upper quantiles and the maximum can be of much value in the study of maximum contaminant level (MCL) violations and population exposures to toxic chemicals above and beyond certain threshold levels. Since large‐valued observations affect the estimates of different parameters differently, it is extremely important to choose the relevant parameter first and then study the change in its estimate based on the deletion of large‐valued observations.Note: For the sake of brevity, the terms mean, standard deviation, and quantiles (or percentiles) are often used in this paper, instead of the more precise estimated mean, estimated standard deviation, and estimated quantiles (or percentiles).
The Recharge‐Discharge Function of Wetlands Near Juneau, Alaska: Part I. Hydrogeological Investigations
Authors: Siegela D.I. 
Published: March 2006

ABSTRACTWater levels in piezometers and the hydraulic conductivity of organic and mineral soils were measured during spring and summer 1986 to evaluate the recharge‐discharge function of wetlands in the vicinity of the Mendenhall Valley near Juneau, Alaska. Computer modeling experiments were also done to evaluate the function of a large patterned fen.The blanket bogs are probably recharge zones, whereas forested wetlands are discharge zones. Approximately the upper third of the patterned fen is a ground‐water recharge zone, whereas its northern margin receives ground‐water discharge from flow systems recharged on moraines.The amounts of wetland recharge and discharge are very small. Recharge from wetlands to viable aquifers is probably less than 1% of the total annual recharge to the aquifer system. The amount of ground‐water discharge to streams from wetlands is too small to measure.
An Automated Numerical Evaluation of Slug Test Data
Authors: Kemblowski M. W. , Klein C. L. 
Published: March 2006

ABSTRACTDevelopment of a numerical algorithm to analyze slug test data is described. This type of test is very popular for aquifer testing, primarily because of its simplicity. Many such tests are performed to estimate the hydraulic conductivity values of ground‐water‐bearing formations. Those values in turn are used to calculate pore‐water velocities. The algorithm was coded and successfully tested for a hypothetical data set. It has also been applied at a number of field locations. One such application is presented.
Analysis of Sustained Ground‐Water Withdrawals by the Combined
Authors: Chau T. S. 
Published: March 2006

ABSTRACTThe long‐term ground‐water withdrawal potential of a regional confined aquifer in the Cold Lake area is analyzed with a combined simulation‐optimization model. The Galerkin finite‐element method is used in the simulation model to obtain numerical approximations to the hydraulics of ground‐water flow. This method produces a set of linear algebraic equations containing ground‐water variables which are embedded as equality constraints within the constraint set of a linear programming optimization model. Other constraints in this set include restrictions on drawdown, water demand, and hydraulic gradient. The objective of the optimization model is to maximize total withdrawal from potential ground‐water development sites. The objectives of this modeling study are to assist planners and water managers in formulating a long‐term water management plan on water allocation to industrial users and to establish a long‐term withdrawal limit for the aquifer. Analyses include the determination of users’ground‐water withdrawals to maximize total ground‐water use from the aquifer, the analysis of ground‐water supply tradeoff among water users, and the identification of pumping locations and their pumpages that best intercept ground‐water flow in the aquifer system. Modeling results show that there is an interdependency of optimal ground‐water withdrawals among water users. The maximum total withdrawal obtained from potential ground‐water development sites is 90 percent of total inflow into the aquifer. This withdrawal limit for the aquifer can be increased with a new set of sites chosen for ground‐water development.
Ground‐Water Flow Model of Drawdown and Recovery Near an Underground Mine
Authors: Toran Laura , Bradbury Kenneth R. 
Published: March 2006

ABSTRACTThe U.S. Geological Survey's modular code (McDonald and Harbaugh, 1984) was used to reconstruct past ground‐water flow paths and make predictions of future flow patterns to understand movement of sulfate‐contaminated ground water through a carbonate aquifer near an underground mine. The abandoned mine is in the zinc‐lead district near the town of Shullsburg in southwestern Wisconsin. The model predicts observed hydraulic head distributions and ground‐water discharge rates with fair accuracy. Instantaneous dewatering rates are underestimated, but long‐term rates can be estimated with the model. The persistence of a cone of depression at present and in the future allows uncontaminated water from surrounding areas to dilute the sulfate, as confirmed by chemical sampling. The model predicts radial flow will persist near the Shullsburg mines until approximately 1988.The model represents a significant test of the ability of a ground‐water flow model to predict the impacts of underground mining on ground‐water systems. The method used required field data collected before, during, and after mining. A model calibrated to just one or two of these data sets is likely to have larger associated uncertainties.
Role of Interceptor Ditches in Limiting the Spread of Contaminants in Ground Water
Authors: Zheng C. , Bradbury K. R. , Anderson M. P. 
Published: March 2006

ABSTRACTThe ground‐water pattern in the vicinity of an interceptor ditch used for agricultural drainage is simulated using flow and stream function models to explore the possibility of using interceptor ditches to control the spread of agricultural chemicals in shallow aquifers. The concept of the dividing streamline is used to quantify the effectiveness of the interceptor ditch for limiting the spread of potential contaminants. The simulation results suggest that the interceptor ditch may create an effective hydraulic barrier to the movement of agricultural contaminants in ground water, but its effectiveness is subject to seasonal changes in hydrological conditions, including the regional water‐table gradient, the distribution of recharge and discharge, and the ditch stage. A quantitative relationship between effectiveness of the ditch and these hydrological conditions is established.
“Testing” a Limestone Aquifer Using Water‐Table Response to Storm Water Discharged into Sinkholes
Authors: Michalski Andrew , Torlucci Joseph 
Published: March 2006

ABSTRACTThe character and performance of karstified aquifers are often difficult to assess, casting some doubt as to the monitorability of waste management facilities located in karstic settings. In the case of a Puerto Rican aquifer presented herein, analysis of water‐table response to storm water discharged to sinkholes allowed characterization of the flow type in the aquifer, estimation of aquifer parameters, and aided in assessing the monitorability of the site.Water‐level data from observation wells have indicated that storm water discharged into on‐site sinkholes produced fairly regular mounding patterns in the aquifer. Such patterns suggested an isotropic character and predominantly diffuse ground‐water transmission within the aquifer. An injection well analogy was used for storm‐water discharge at the sinkholes to analyze the water‐level data and estimate values of aquifer parameters.The case presented herein demonstrates that analysis of transient water levels in response to natural stresses can provide a useful tool of hydrogeologic exploration at sites where sinkholes act as strong and variable point sources. At such sites, traditional well pumping/injection tests may be subject to excessive interference from the sources and lead to erroneous interpretations.
Biodegradation of Surfactants in Saturated Subsurface Sediments: A Field Study
Authors: Federle Thomas W. , Pastwa Gary M. 
Published: March 2006

ABSTRACTThe mineralization of linear alkylbenzene sulfonate (LAS), linear alcohol ethoxylate (LAE), benzylamine, and monoalkyl and dialkyl quaternary ammonium compounds was determined as a function of depth in sediment profiles from beneath a laundromat waste‐water pond and pristine control pond. In addition, bacterial number, microbial activity, and concentrations of LAS and quaternary ammonium compounds were measured. Surfactant concentration decreased dramatically with increasing depth in the laundromat profile. Bacterial number and activity decreased with depth in both profiles; however, biomass and activity were higher in the laundromat profile. Mineralization was measured by amending samples with 14C‐labeled substrates and following the evolution of 14CO2 with time. LAS was mineralized without a lag period at all depths in the laundromat profile; its half‐life ranged from 3.2 to 16.5 days. In the control pond, it was mineralized more slowly (half‐life 5.2 to 1540 days) and only after a lag period of 2 to 40 days. LAE was also mineralized with shorter lags and more rapidly in the laundromat than in the control profile; half‐lives ranged between 2.8 to 8.6 days in the former and 3.5 to 137 days in the latter. Although monoalkyl and dialkyl quaternary ammonium compounds were not mineralized in the control profile, slow but significant mineralization of these compounds occurred in the laundromat profile. Benzylamine was rapidly degraded without a lag in both profiles. Field concentration data and the results of mineralization studies indicated that biodegradation combined with the effects of adsorption is a practical mechanism of surfactant removal in subsurface environments. In addition, adaptation resulting from exposure of microbial communities to surfactants is an important factor governing the fate of surfactants in the subsurface.
Forced‐Gradient Tracer Tests and Inferred Hydraulic Conductivity Distributions at the Mobile Site
Authors: Molz Fred J. , Güven Oktay , Melville Joel G. , Nohrstedt J. Steven , Overholtzer Jon K. 
Published: March 2006

ABSTRACTFour single‐well tracer tests and a two‐well tracer test performed in a 21‐m thick confined granular aquifer at a field site near Mobile, Alabama, are described. The data from these tests together with previously published data from a single‐well test and a two‐well test allow one to begin to develop a three‐dimensional picture of the hydraulic properties of the study aquifer. A consistent feature of all the tests is a high hydraulic conductivity zone which appears in the bottom third of the aquifer. This result is in agreement with hydraulic conductivity distributions inferred from previous aquifer thermal energy storage experiments at the same site. In some locations the new tests indicated high hydraulic conductivity zones in the upper third of the aquifer which were not detected in the previous two‐well test and single‐well tests performed at the same site but at different locations. Despite the three‐dimensional spatial variations of hydraulic conductivity indicated by these tests, it was possible to predict the major features of the tracer concentration as a function of time at the withdrawal well in the two‐well test by means of an available numerical model assuming perfect stratification at the test site and using a hydraulic conductivity distribution inferred from a single‐well test.The apparent success of the model prediction presented here, as well as the success of a similar numerical simulation of the previous two‐well test reported earlier, seem to support the conclusion that the study aquifer has an approximately stratified flow field at the test site. These field test results provide further evidence that reliable predictions of solute transport in a real aquifer will depend on a sufficiently detailed knowledged of the major features of the three‐dimensional advection pattern in the aquifer. Based on this study and previous studies, it appears that a healthy mixture of viewpoints and techniques (geologic, hydrologic, geophysical, etc.) will be necessary to characterize the transport properties of natural ground‐water systems.
Dimensionless Time‐Drawdown Plots of Late Aquifer Test Data
Authors: Şen Zekâi 
Published: March 2006

ABSTRACTThe Jacob straight‐line method is concerned with the late time Theis type curve. The Jacob method gives a straight line on semilogarithmic paper. In practice, the Jacob straight line is taken for granted by ground‐water hydrologists, hydrogeologists, and engineers, and applied almost universally. Not every straight line on semilogarithmic paper, however, warrants the application of the Jacob method. The Jacob straight‐line method has physical restrictions (in addition to the mathematical requirements of having the dimensionless time factor, u, less than 0.01) which are ignored. Therefore, determination of the storage coefficient and transmissivity from the semilogarithmic plot of data yields either over or underestimations.The objective of this paper is to show that the slope of the straight line on semilogarithmic paper can provide useful quantitative information for the proper application of the Jacob method. Differences in the slopes of the theoretical and field lines implies various physical circumstances. In practice, the Jacob method must be used with great care. The physical construction of the aquifer and flow conditions must be considered.
Molecular Analyses of the Interaction ofBorrelia hermsiiFhbA with the Complement Regulatory Proteins Factor H and Factor H-Like Protein 1
Authors: Hovis Kelley M. , Jones Janice P. , Sadlon Tania , Raval Gauri , Gordon David L. , Marconi Richard T. 
Published: March 2006

ABSTRACTBorrelia hermsii, the primary etiological agent of tick-borne relapsing fever in North America, binds the complement regulatory protein factor H (FH) as a means of evading opsonophagocytosis and the alternative complement pathway. The ability of FH-binding protein A (FhbA) to bind FH-like protein 1 (FHL-1) has not been assessed previously. In this study, using a whole-cell absorption assay, we demonstrated thatB. hermsiiabsorbs both FH and FHL-1 from human serum. Consistent with this, affinity ligand binding immunoblot analyses revealed that FH constructs spanning short consensus repeats 1 to 7 and 16 to 20 bind to FhbA. To investigate the molecular basis of the interaction of FhbA with FH/FHL-1, recombinant FhbA truncated proteins were generated and tested for FH/FHL-1 binding. Binding required determinants located in both the N- and C-terminal domains of FhbA, suggesting that long-range intramolecular interactions are involved in the formation and presentation of the FH/FHL-1-binding pocket. To identify specific FhbA residues involved in binding, random mutagenesis was performed. These analyses identified a loop region of FhbA that may serve as a contact point for FH/FHL-1. The data presented here expand our understanding of the pathogenic mechanisms of the relapsing fever spirochetes and of the molecular nature of the interaction between FH/FHL-1 and FhbA.
Active Cytotoxic Necrotizing Factor 1 Associated with Outer Membrane Vesicles from UropathogenicEscherichia coli
Authors: Kouokam J. Clavin , Wai Sun Nyunt , Fällman Maria , Dobrindt Ulrich , Hacker Jörg , Uhlin Bernt Eric 
Published: March 2006

ABSTRACTCytotoxic necrotizing factor type 1 (CNF1) is one of the virulence factors produced by uropathogenicEscherichia coli(UPEC). How this toxin is translocated from the bacterial cytoplasm to the surrounding environment is not well understood. Our data suggest that CNF1 may be regarded as a secreted protein, since it could be detected in culture supernatants. Furthermore, we found that CNF1 was tightly associated to outer membrane vesicles, suggesting that such vesicles play a role in the secretion of this protein. Interestingly, vesicle samples containing CNF1 could exert the effects known for this protein on HeLa cell cultures, showing that CNF1 is transported by vesicles in its active form. Taken together, our results strongly suggest that outer membrane vesicles could be a means for the bacteria to deliver CNF1 to the environment and to the infected tissue. In addition, our results indicate that the histone-like nucleoid structuring protein H-NS has a role in the downregulation of CNF1 production and that it affects the outer membrane vesicle release in UPEC strain J96.