bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lucky Girls: Unintentional Avoidance of Adolescent Pregnancy Among Low‐Income African‐American Females
Authors: Martyn Kristy K. , Hutchinson Sally A. , Martin Jacquelyn H. 
Published: February 2007

PURPOSE. To describe lucky adolescents who unintentionally avoid pregnancy.DESIGN AND METHODS. The second phase of a descriptive qualitative study in which 17 low‐income African‐American females ages 19 to 26 participated in open‐ended interviews on how they avoided pregnancy as adolescents.RESULTS. Constant comparative analysis revealed that five of the girls avoided pregnancy because they were “lucky“ that others insisted they use contraceptives. These lucky girls were unaware of sexual risks, but used contraceptives because they complied with decisions made by their parents, grandparents, and partners.PRACTICE IMPLICATIONS. Lucky girls are at risk for adolescent pregnancy because they abdicate decision making to others and are likely to be overlooked in practice because they are using contraceptives. Promoting self‐protection includes assessment, knowledge, skills‐building strategies, and health‐promoting contracts between the nurse and adolescent.
The Application of Combined Seismic and Electrical Measurements to the Determination of the Hydraulic Conductivity of a Lake Bed
Authors: Taylor Robert W. , Cherkauer Douglas S. 
Published: February 2007

AbstractThe hydraulic properties of lake beds control the interactions between lakes and ground water systems, but these properties are normally difficult to measure directly. The authors’method combines seismic reflection and electrical measurements to map the relative hydraulic conductivity of lake bed sediments. A shipboard seismic profiling system provides sediment thickness, while a towed electrical array yields longitudinal conductance and electrical chargeability. The sediment's leakance (hydraulic conductivity/thickness) can be calculated from the longitudinal conductance data. Leakance may then be converted to relative hydraulic conductivity through the seismically derived sediment thicknesses. Simultaneously acquired electrical chargeability provides an independent measure of clay content. The seismic and electrical systems are computer automated and yield production rates of approximately five line‐kilometers/hour or 300 electrical soundings/hour. The systems provide continuous hydraulic information along the ship track rather than the point information derived from coring.The procedure and systems have been used to map the bed of Lake Michigan offshore from an area of heavy pumpage. This location has been chosen to test the method because lake water has intruded the aquifer in plumes largely controlled by lake bed hydraulics. Mapping these plumes onshore permits the inference of the spatial distribution of offshore hydraulic conductivities. Offshore seepage measurements and numerical, chemical transport modeling of this site have confirmed the reliability of the geophysically derived hydraulic conductivities and have also demonstrated the improvement in numerical results achieved through the availability of spatially determined hydraulic conductivities.
A State‐Of‐The‐Art Approach to Hydrologic Data Management
Authors: Way S.C. , Wainwright H.K. , Ward W.P. 
Published: February 2007

AbstractHigh‐accuracy electronic data acquisition equipment, a solid‐state memory, computer interface and software have been developed to provide a complete system for measuring and recording water level changes.A small, stand‐alone hydrologic instrument (SE1000) provides the automation and accuracy of solid‐state electronics in pump tests, slug tests, and long‐ and short‐term ground water monitoring. The unit is powered by a high‐performance battery pack with a minimum life of four years. This instrument can be buried at the monitoring site for protection from vandals, animals and temperature extremes. Ten pre‐programmed 949‐point data schedules are standard. One schedule is logarithmic with an initial data interval of 0.2 seconds. Nine linear schedules provide data intervals ranging from 15 minutes to 1.5 days and corresponding test durations ranging from 10 days to 46 months. The stored data can be recovered directly via the LCD display or transferred to a computer. Software provides automatic data reduction with hard copy tables and plots.This instrument has been used successfully in various locations in the United States.
Environmental Analysis of Iron‐Precipitating Bacteria in Ground Water and Wells
Authors: Smith Stuart A. , Tuovinen Olli H. 
Published: February 2007

AbstractIron‐precipitating bacteria are frequently cited as being involved in economically serious well and aquifer degradation that may also have a public health impact. Quantifying the populations of the iron‐precipitating bacteria present in ground water is a complex problem not yet resolved. A survey of historical and modern environmental literature provides numerous descriptions of iron bacteria in aquifers and wells, along with physicochemical data collected during bacterial sampling. These data are not conclusively linked with iron bacteria occurrence. Iron bacteria is a concept encompassing many genera and species of bacteria with varying morphology and physiology. Methods to detect bacteria and to quantify bacterial biomass in aquifers are being developed, but representative sampling remains a problem. Predictive analysis of iron bacterial growth awaits additional physiological and sampling research.
Geophysical Techniques to Delineate Saturated Alluvial Zones for the Siting of HVDC Power Transmission Return Electrodes
Authors: Hennon Kerry 
Published: February 2007

AbstractAs high‐voltage, direct‐current (HVDC) electrical power transmission technology advances, the siting and design of the grounded return electrodes become critical factors. Electrode sites should be chosen where surrounding geologic conditions will not unfavorably channel large earth currents and harmfully affect nearby populations. An optimum site allows direct contact between the electrode and a large volume of a stable, low‐resistivity material. A saturated alluvial zone between dry surface soils and an underlying crystalline bedrock is an ideal material for containing the current flow from the electrode.A hydrogeologic investigation was conducted to delineate the saturated zone in several alluvial valleys in the southwestern desert region. Regional ground water flow directions, water quality, and seasonal fluctuations of the water table elevations were determined. The structural shape and topography of the crystalline basement beneath the valleys were interpreted from gravity data. Iterative forward‐modeling of the data provided a low‐cost means of deducing the volume of the lightweight alluvium. Electrical resistivity surveys were completed to measure the lateral and vertical variations in soil resistivities throughout the valleys. The geophysical data were used to extend the known hydrologic information into areas with no wells.Composite models of the saturated zones in each valley were produced by integrating gravity interpretations with hydrologic and resistivity results. The composite models were used to predict current density in the ground that would be associated with a HVDC electrode. This methodology proved to be a cost‐effective means of siting electrodes in a suitable geologic environment that would minimize their detrimental effects.
Chemical Fate of Injected Wastes
Authors: Scrivner Noel C. , Bennett Karl E. , Pease Richard A. , Kopatsis Alex , Sanders Steven J. , Clark Diane M. , Rafal Marshall 
Published: February 2007

AbstractThe chemical fate of wastes put into disposal wells can be determined using standard chemical engineering techniques. The concentration of hazardous constituents is typically reduced by reactions within the waste itself or by reactions with the injection zone material, thus reducing any potential impact on the environment. Such reactions include neutralization, hydrolysis, ion exchange, adsorption, precipitation, co‐precipitation and microbial degradation.Extensive research was done to quantify these phenomena, so they could be used in a predictive model.Neutralization, hydrolysis and precipitation were modeled using data from the open literature: reaction rates and equilibrium constants for the dominant reactions were incorporated into a sophisticated computer simulation that calculates solid‐liquid equilibria of aqueous electrolyte solutions.The model predicted the fate of two waste streams: (1) high‐pH, cyanide‐containing waste injected into sandstone is made less hazardous by hydrolysis and sand dissolution, and (2) FeCl3‐FeCl2 HCl‐H2 O waste is made non‐hazardous by reaction with dolomite. Experiments are planned to confirm certain model predictions. Further development and public access of the model are planned.
Theory, Construction and Operation of Simple Tensiometers
Authors: Stannard David I. 
Published: February 2007

AbstractThe tensiometer, introduced by Richards and Gardner (1936) has been a tool often ignored in unsaturated zone investigations. Hazardous waste disposal studies that require values of unsaturated zone matric potentials will expand tensiometer use. Familiarity with operation and installation principles is necessary to ensure quality data collection.The essential elements of a tensiometer are a porous cup connected with tubing to a vacuum gauge; all are filled with water. When the porous cup is buried in unsaturated soil, the soil draws water through the cup wall, until the water tension inside the cup equals the surrounding soil‐water tension. The tension is transmitted through the water filled tube to an accessible vacuum gauge (manometer or transducer) and is recorded manually or automatically.Although specialized tensiometers exist, the tensiometer presented here in detail is suited to diverse on‐site applications. Constructed from readily available, inexpensive parts, it can measure as much as 0.85 bar of tension. Design features include a flushing system for removal of entrapped air or mercury, and an easily maintained modular network of nylon manometers and water‐supply tubes.Good hydraulic connection between porous cup and soil and meticulous backfill procedures are necessary for accurate measurement of representative matric potentials. Proper and consistent use of tensiometers should yield reliable values of matric potentials, and lead to a better understanding of unsaturated zone processes.
Suitability of Polyvinyl Chloride Well Casings for Monitoring Munitions in Ground Water
Authors: Parker Louise V. , Jenkins Thomas F. 
Published: February 2007

AbstractA number of samples of polyvinyl chloride (PVC) well casings used for ground water monitoring that varied in schedule, diameter or manufacturer were placed in contact with low concentrations of aqueous solutions of TNT, RDX, HMX and 2,4‐DNT for 80 days. Analysis indicated that there was more loss of TNT and HMX with the PVC casing than with the glass controls, but that the amount lost was, for the most part, equivalent among different types. A second experiment was performed to determine if these losses were due to sorption or if biodegradation was involved. Several different ground water conditions were simulated by varying salinity, initial pH and dissolved oxygen content. The only case where there was an in‐creased loss of any substance due to the presence of PVC casing was with the TNT solution under non‐sterile conditions. The extent of loss was small, however, considering the length of the equilibration period. This increased loss is thought to be associated with increased microbial degradation rather than sorption. Several samples of PVC casing were also leached with ground water for 80 days. No detectable interferences were found by reversed‐phase high performance liquid chromatography (HPLC) analysis. Therefore, it is concluded that PVC well casings are suitable for monitoring ground water for the presence of these munitions.
Shallow Seismic Refraction Survey of Near‐Surface Ground Water Flow
Authors: Sverdrup Keith A. 
Published: February 2007

AbstractA shallow seismic refraction survey was conducted as part of a geologic and hydrologic investigation of an area adjacent to a proposed coal strip mine in southeastern Illinois. Data obtained from the survey were used to estimate the thickness and geometry of litho‐logic units within approximately 40 feet of the surface in unconsolidated material overlying bedrock. Data from a nearby ground water monitoring well and several shallow geologic cores obtained in the survey area indicated the presence of a silt‐clay unit roughly 10 feet beneath the surface. This unit strongly inhibits the vertical movement of ground water, resulting in a perched water table.The refraction survey revealed that the morphology of the top of this silt‐clay layer is dominated by a narrow, sinuous channel criss‐crossing the survey region with an overall downward trend in elevation from the mine site to a small creek roughly 0.25 miles away. Detailed knowledge of the location of this channel was used to identify optimal sites for shallow ground water monitoring stations. The method proved to be a relatively rapid and cost‐efficient means of obtaining detailed information concerning the thickness and geometry of the near‐surface unconsolidated materials.
A Low‐Cost System to Remotely Measure Piezometric Head
Authors: Schaefer Mark E. , Hemond H.F. 
Published: February 2007

AbstractAlow‐cost rapid response system to remotely collect piezometric head data in compressible porous media has been constructed. The system is based on low‐cost temperature compensated pressure transducers, standard low‐cost CMOS logic devices, low‐cost commercially available two‐way radios and a portable microcomputer. The basic system operation involves encoding a pressure transducer output, which is then transmitted on command via two‐way FM radios to a base station located up to one‐half mile away. The base station includes a TRS‐80 Model 100 microcomputer which controls the network of remote stations and decodes and stores the information. This information is partially processed in the microcomputer and may be readily transferred to a mainframe for further data analysis. The base station interrogates as many as 16 remote stations at a specified sampling rate. The versatility of the system also allows it to be used to operate any remote instrumentation system having a suitable voltage output.
Electronic Sensing Devices Used for In Situ Ground Water Monitoring
Authors: Ritchey Joseph D. 
Published: February 2007

AbstractProgress in the fields of electronics and computers has produced data‐acquisition equipment beneficial to ground water field studies. This equipment controls data collection from sensing devices and saves the data for later processing. There are many types of sensors available for in situ use in water quality monitoring wells, observation wells and water supply wells. Sensors are separated into two groups, those used to measure water levels and those used to measure water quality parameters.There are three major types of sensors for measuring water levels. They are floats, transducers and acoustic devices. Most types have proven accuracy and can be successfully applied to short‐term monitoring (i.e., aquifer tests) and long‐term field studies (i.e., one month to multi‐year trend analyses). They are most cost‐effective when augmented with the programmability of computers. For example, water level measurements are made only when the water level has changed some predetermined amount.Sensors to measure water quality include those that measure temperature, pH, specific conductance, dissolved oxygen and specific ions. Unlike water level sensors the accuracy of water quality sensors, with the exception of temperature, is difficult to verify in field conditions. This is because measurement of water quality parameters is dependent on the water in contact with the sensor being representative of the ground water in the formation. In addition, the performance of the sensor over periods greater than a few hours is reduced either because of the naturally occurring constituents in the water that interfere with the sensor or because of loss of sensor calibration.A potential use of water quality sensors for in situ investigations is to aid in surveillance monitoring to indicate the arrival of contaminants at the earliest possible moment. This has a narrow limit of practicality at this time because of problems associated with sensor accuracy.Many water quality sensing devices are well‐suited for research purposes. This includes measuring the migration of thermal fronts and application in conducting tracer tests.
An In Situ Multilevel Sampler for Preventive Monitoring and Study of Hydrochemical Profiles in Aquifers
Authors: Ronen Daniel , Magaritz Mordeckai , Levy Itzhak 
Published: February 2007

AbstractA modular multilevel sampler was developed and utilized for sampling undisturbed ground water chemical profiles and gases in both the saturated and the unsaturated zone. Sampling at 3cm depth intervals is based on the dialysis‐cell method and has no depth limitations. The sampler may be used for the development of early warning monitoring systems and research.
Simulation of Sampling and Hydraulic Tests to Assess a Hybrid Monitoring Well Design
Authors: Cohen Robert M. , Rabold Richard R. 
Published: February 2007

AbstractDetermination of the nature, extent, and rate of off‐site chemical migration are common objectives of hazardous waste site investigations. Chemical analyses of water samples from monitoring wells and measurements of hydraulic head and hydraulic conductivity provide the basis for making these determinations. Accurate site assessment, therefore, depends upon the appropriate monitoring well design and sampling and testing procedures.During the course of remedial investigations in Niagara Falls, New York, it has been necessary to evaluate the ground water quality and hydraulic characteristics of 5‐ to 30‐feet thick overburden formations. Many of the monitoring wells completed to these formations consist of a partially penetrating screen (5 feet at the base of the formation) with a fully penetrating sandpack. Questions regarding how this well design influences the source of sampled ground water and hydraulic tests were examined using an extremely fine axisymmetric grid with SATURN, a two‐dimensional, finite‐element ground water model, and a particle tracking post‐processor.A discrete sensitivity analysis was made to determine how flow patterns induced by pumping at 1 gpm are affected by: different screen and sandpack configurations, the ratio of sandpack to formation hydraulic conductivities, heterogeneity, anisotropy, and sandpack thickness. The simulations show that the source (and chemistry given a non‐uniform chemical distribution) of ground water sampled will vary considerably depending on a number of factors. Analysis of simulated drawdowns in the monitoring well during purging shows that calculated transmissivities for the range of well designs and conditions modeled will be accurate to within one‐half order of magnitude.
The Effect of Construction, Installation, and Development on the Turbidity of Water in Monitoring Wells in Fine‐Grained Glacial Till
Authors: Paul Duane G. , Palmer Carl D. , Cherkauer Douglas S. 
Published: February 2007

AbstractTwenty monitoring wells were installed in fine‐grained glacial till at two sites in southeastern Wisconsin to study the effects of monitoring well construction, installation, and development on the amount of fine‐grained suspended material in the well. The types of well screens used were continuous slot, factory slot, factory slot with a filter wrap, and porous piezometer tips. Some of the wells were installed before the open borehole began to fill with water; others were installed after the water levels in the lower section of the borehole had begun to rise. About half of the wells were developed by surging while the others were simply bailed without surging. Installation of the wells in the initially dry holes resulted in wells that yielded samples with very low turbidity compared to wells installed in wet holes. Water samples from wells that were surged were more turbid than those that were not. The type of construction materials investigated had no effect on the turbidity of samples from the wells.
Monitoring the Vadose Zone in Fractured Tuff
Authors: Montazer Parviz , Weeks E.P. , Thamir Falah , Hammermeister Dale , Yard S.N. , Hofrichter Peter B. 
Published: February 2007

AbstractUnsaturated tuff beneath Yucca Mountain, Nevada, is being evaluated by the U.S. Department of Energy as a host rock for a potential repository for high‐level radioactive waste. As part of the Nevada Nuclear Waste Storage Investigations Project of the U.S. Department of Energy, the U.S. Geological Survey has been conducting hydrologic, geologic and geophysical investigations at Yucca Mountain and the surrounding region to provide data for evaluation of the potential suitability of the site. Hydrologic investigations of the unsaturated zone at this site began in 1982. A 17.5‐inch‐ (44.5‐centimeter) diameter borehole (USW UZ‐1) was drilled by the reverse‐air vacuum‐drilling technique to a depth of 1269 feet (387 meters). This borehole was instrumented at 33 depth levels. At 15 of the levels, three well screens were embedded in coarse‐sand columns. The sand columns were isolated from each other by thin layers of bentonite, columns of silica flour, and isolation plugs consisting of expansive cement. Thermocouple psychrometers and pressure transducers were installed within the screens and connected to the data‐acquisition system at the land surface through thermocouple and logging cables. Two of the screens at each level were equipped with access tubes to allow collection of pore‐gas samples. In addition to these instruments, 18 heat‐dissipation probes were installed within the columns of silica flour, some of which also had thermocouple psychrometers.After more than two years of monitoring, the majority of the instruments were still functioning and producing reasonable data. A slow recovery from the disturbed state to natural conditions was detected during the first 90 days of monitoring; this recovery was probably a result of the large diameter of the borehole. Preliminary results indicated that suction pressures for the welded units ranged from −2 to −15 bars (−0.2 to −1.5 mega pascals). Some agreement existed between data from psychrometers and from heat‐dissipation probes, except where silica flour was not in equilibrium with the formation. Water fluxes estimated in the matrix of the repository host‐rock unit range from 4 × 10−3 to 2 × 10−2 inches per year (0.1 to 0.5 millimeter per year) using matric‐potential distribution, and from −1 × 10−3 to −2 × 10−3 inches per year (−0.025 to −0.05 millimeter per year) using geothermal gradient.Responses to short‐term barometric fluctuations were detected to a maximum depth of about 300 feet (91 meters) in the borehole. Below this depth, only long‐term barometric fluctuations were detectable. Equivalent effective hydraulic conductivity, estimated from air permeability, ranged from 0.6 to 2 feet per day (0.2 to 0.6 meters per day).