bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of LNAPL Biodegradation Products on Electrical Conductivity Measurements
Authors: Cassidy Daniel P. , Werkema D. Dale , Sauck William , Atekwana Estella , Rossbach Silvia , Duris Joe
Published: September 2009

Field geophysical studies have identified anomalously high conductivities in and below the free product zone at many sites with aged contamination by light, non-aqueous phase liquids (LNAPL). Laboratory experiments were conducted to test the hypothesis that these anomalously high conductivities can result from products of LNAPL biodegradation. Soil from a hydrocarbon-impacted site with anomalously high conductivities was washed repeatedly to remove soluble constituents, recontaminated with diesel fuel (DF), and the pores filled with water to simulate a saturated smear zone. Nutrients were provided at levels observed at the site, which resulted in anaerobic conditions due to DF biodegradation. Within [Formula: see text], the increase in specific conductivity from microbial activity was [Formula: see text], caused by an increase in total dissolved solids (DS) of over [Formula: see text]. The increase in DS was due to mineral (mostly carbonate) dissolution and to the production of organic acids and biosurfactants. Under aerobic conditions (i.e., without added nutrients) products of DF biodegradation increased the total DS and conductivity by [Formula: see text] and [Formula: see text], respectively. The results show that products of LNAPL biodegradation can drastically increase the conductivity at impacted sites.
Surface-Wave Group-Velocity Tomography for Shallow Structures
Authors: Long Leland Timothy , Kocaoglu Argun H.
Published: September 2009

Because the Rayleigh waves generally have the largest amplitude of all waves generated by a vertical surface impact and because the near-surface shear-wave velocity primarily determines the Rayleigh wave velocity, the Rayleigh waves may be used to image shallow shear-wave structures. The Rayleigh wave group velocity can be measured from records of surface waves that have traversed a study area, typically, with a surface source on one side and an array of geophones along the opposite side. The multiple-filter technique is used for group velocity determination. First, each trace is narrow-band filtered and the instantaneous amplitude of its complex trace is computed. Second, the time of the peak in the instantaneous amplitude of the complex trace consistent with the mean group travel time is identified. Third, all the observed group travel times are corrected for group delays introduced by instrument response, geophone ground coupling and the source time function. Finally, the effect of noise can be minimized by constraining the observed group arrival times to be consistent among arrivals that follow similar paths. By obtaining data from different source and receiver locations, the resulting group travel times can be used in a tomographic inversion to image the distribution of group velocity within the study area. The tomographic inversion is repeated for many frequencies giving a dispersion curve for each point in the study area. Then, vertical shearwave velocity structure at any point can be interpreted from its dispersion curve. In this study we obtained data covering a square area that was [Formula: see text] on a side. Usable group velocities were obtained for frequencies from [Formula: see text] using a sledgehammer source. The resulting tomographic image and velocity anomaly was sufficient to delineate a suspected [Formula: see text] deep burial trench.
Resistivity and Radar surveys at the Archaeological site of Ercolano
Authors: Carrara E. , Carrozzo M. T. , Fedi M. , Florio G. , Negri S. , Paoletti V. , Paolillo G. , Quarta T. , Rapolla A. , Roberti N.
Published: September 2009

In this paper we describe the application of GPR and resistivity (dipole-dipole) methods to an archeological investigation. The aim of this study was to obtain information about buried pre-Roman structures below the Roman residence “Casa dell’Atrio a Mosaico,” in the ancient town of Ercolano (Naples). A number of resistivity (dipole-dipole) and GPR profiles were carried out on the mosaic floor of the house. To perform resistivity profiles in a nondestructive way on the mosaic floor, special flat-base copper electrodes were used. The electrode spacing used was [Formula: see text] and [Formula: see text]. GPR data were collected using [Formula: see text] and [Formula: see text] antennas. The radar profiles were carried out primarily along the electrical profiles in order to obtain a direct comparison between the two methods. Both resistivity and GPR methods evidenced a number of structures buried at shallow depths. Both methods located a structure identified as a conductive body with electric parameters strongly contrasting those of the surrounding material. The archaeological interpretation of such structures is in terms of remnants of walls of pre-Roman houses and of a cistern used for collecting rain, connected to a pipe.
Seismic Measurements of Ground Displacements Caused by Trains and Quarry Blasts at the Superconducting Super Collider Site in Texas
Authors: Lesmes David , Morgan Frank Dale
Published: September 2009

Ground vibrations caused by cultural noise sources such as road traffic, trains, and quarry blasts can significantly affect sensitive scientific experiments and manufacturing processes. When constructing a facility that requires ultra-stable ground conditions it is prudent to first measure the level of background noise at the proposed site. In this study, seismic measurements are used to measure near-surface ground vibrations at the superconducting super collider (SSC) site in the state of Texas. The SSC is an oval shaped ring, which is [Formula: see text] in circumference. A design limit of the SSC is that the ground vibrations should be less than [Formula: see text] [Formula: see text] in amplitude. Seismic measurements of ground velocity were made, both at the surface and within boreholes, at several sites around the proposed SSC ring. Through a series of data processing steps the ground velocity measurements were transformed into ground displacements. Ground displacements caused by quarry blasts were sufficiently small at the SSC ring such that they posed no problem for the design and operation of the SSC. However, ground displacements caused by trains at railroad crossings significantly exceeded the displacement tolerance level of the SSC design. Furthermore, the peak amplitude in the spectra of the measured ground velocity shifted from [Formula: see text] near the railroad tracks to [Formula: see text] far from the tracks [Formula: see text]. The peak ground displacements, however, occurred at frequencies less than [Formula: see text] in both the near-field and far-field measurements. If the SSC construction had continued, it would have been necessary to either re-engineer the train tracks and railroad crossings to reduce the amount of ground vibration or to re-route the trains around the SSC ring. In August 1993, however, the United States Congress ordered the Department of Energy to halt construction on the multi-billion dollar SSC project.
Use of SASW Measurements to Evaluate the Effect of Lime Slurry Conditioning in Drilled Shafts
Authors: Kalinski M. E. , Ata A. , Stokoe K. H. , O’Neill M. W.
Published: September 2009

Spectral-Analysis-of-Surface-Waves (SASW) testing was conducted in untreated and treated drilled shafts at the NGES “TXHOUSTO” test site as part of a study on lime-slurry conditioning of soil in drilled shafts for pier foundation construction. Results of SASW testing in an untreated shaft revealed a reduction in shear wave velocity ([Formula: see text]; a measure of small-strain shear stiffness) within an annular zone slightly less than one shaft diameter in thickness. This reduction is attributed to stress relief and soil disturbance during excavation. Results of SASW testing in a treated shaft revealed that [Formula: see text] of the soil surrounding the shaft depended upon whether the measurement was performed above or below the water table. Above the water table, a thin (less than [Formula: see text]) annulus of stiffen cemented soil was created due to the reaction between the lime and the carbon dioxide in the pore spaces of the partially saturated soil. Since the clay was saturated below the water table, there was no carbon dioxide in the pore spaces available to react with the lime, so there was no observed increase in stiffness due to cementation. As a result of these observations, an alternative strategy for the application of lime-slurry conditioning of drilled shafts in the construction of pier foundations has been conceived.
EMMA—A Geophysical Training and Education Tool for Electromagnetic Modeling and Analysis
Authors: Auken Esben , Nebel Lars , Sørensen Kurt , Breiner Morten , Pellerin Louise , Christensen Niels B.
Published: September 2009

An interactive modeling and analysis program with a user-friendly graphical interface, for students and professionals in the field of exploration geophysics, has been developed. The ElectroMagnetic Modeling and Analysis program—EMMA—is capable of modeling one-dimensional responses for most electrical and electromagnetic methods and array configurations, including the time-domain, frequency-domain, resistivity, magnetotelluric and borehole methods. EMMA is available on-line, at no charge, from http:∕∕www.hgg.au.dk. An innovation of EMMA is the calculation of the model sensitivity analysis, a feature that is usually only present in inversion codes. The variance of the model parameters depends on the variance of the measured data and the way in which an error is mapped from the data to the model parameters. The measurement situation is realized by ascribing data noise to the model response. This facilitates the calculation of a realistic model parameter analysis. For time-domain data, piece-wise linear waveforms, ramps and low-pass filters are included in the forward modeling scheme. When implemented on a multi-user relational database structure, EMMA is suitable for classroom exercises where the computers are connected through a local network. As an illustration and for motivation, three exercises focusing on the time-domain electromagnetic method are presented: the mapping of noise to model resolution; the effect of filters on the early time response and layer resolution: and an examination of the electric and magnetic field intensity to understand the physical mechanisms of the method. Short courses on the subject of the transient electromagnetic and resistivity methods for hydrogeophysical investigations, offered to technical advisers and to technical policy-makers, have demonstrated EMMA’s succes in providing a productive learning environment.
Use of Ground Penetrating Radar to Map Subsurface Moisture Variations in an Urban Area
Authors: Leucci Giovanni , Negri Sergio , Carrozzo Maria Teresa , Nuzzo Luigia
Published: September 2009

The range of Ground Penetrating Radar (GPR) applications is very wide and diverse. GPR provides high-resolution continuos profiles, and has been used in various fields (environmental problems, geology, geotechnical engineering, archaeology etc.). This paper describes a test application of GPR in an urban area (Mesagne, Apulia, Italy) for the detection of underground water pipes and to obtain a map of the moisture in the ground around them. Some authors have proven that GPR can be used effectively, although only as a reconnaissance tool, for studies of moisture in the subsurface. Electromagnetic wave velocity in the subsurface depends on moisture via the dielectric properties of the wet material. The free volumetric water content can be determined from the dielectric constant of subsurface terrain by an empirical relation proposed by Topp et al. (1980). GPR wave velocity determination can be carried out by means of several methods. In this paper the hyperbolic anomalies caused by small inhomogeneities and underground water pipes have been considered. The velocity analysis permitted a qualitative estimation of the volumetric water content near the pipe network and the location of possible leaks.
Characterization of a Contaminant Plume Due to a Hydrocarbon Spill Using Geoelectrical Methods
Authors: Osella Ana , de la Vega Matías , Lascano Eugenia
Published: September 2009

The objective of the research contained in this paper was the characterization of a contaminant plume and the description of the surrounding area, in order to give information for future remediation. The origin of the plume was a hydrocarbon spill produced by fissures in a purge chamber belonging to a gas transmission system. Data from control wells indicated that the soil was composed mainly of clays. The most important result was that, close to the chamber, a [Formula: see text]-thick layer of gasoline was detected at [Formula: see text] depth, floating over the water table. This is a case in which a resistive contaminant like hydrocarbon is located in a conductive medium; in these circumstances geoelectrical prospecting is particularly good for characterizing the zone. The extent of the area under study was [Formula: see text], approximately, and the thicknesses involved were more than [Formula: see text] of, in many cases, very conductive materials. Thus, a field design was required that would cover the zone with deep penetration and at the same time optimize lateral resolution. By combining Wenner and dipole-dipole configurations, the electrical imaging of the contaminated zone and the description of the surrounding soil were achieved.
Mapping an Iron-Meteorite Impact Site with a Magnetometer, and Implications for the Probability of a Catastrophic Impact on Earth
Authors: Wynn J. C.
Published: September 2009

The Wabar meteorite impact site in central Saudi Arabia, first visited by Henry St. John (Abdullah) Philby in 1932, is unique in several ways. It is one of only 17 impact sites on the Earth where part of the original object is still present. The Wabar impact event also took place entirely in sand, permitting a much clearer and simpler reconstruction of the physical processes of a hypervelocity impact. A careful magnetic survey conducted there adds crucial information to this reconstruction: almost none of the [Formula: see text] of the original iron-nickel object remains in or beneath the known impact craters. The magnetic data were difficult to acquire because of the hostile environment, and the processing was non-trivial for what in effect was a magnetic survey of a ferrous junkyard. The event sequence, which took place in just a few seconds, generated a unique binary set of impactite that includes a black glass (90% local sand and 10% meteorite) and a shock-generated, coarsely laminar bleached-white sandstone we have informally named “Instarock.” Very little of the original object survived intact, save some small fragments apparently spalled off by the reflected impact shock-wave against the back of the meteoroid. Most of these fragments are in the form of so-called “shale-balls” buried beneath a shallow sand cover. Despite a [Formula: see text] fission-track date, field relationships suggest a much younger age, a conclusion supported by thermoluminescence dates as low as [Formula: see text]. Along with several other small meteoroid impact events that have come to light in the past few decades, this very young age-date suggests a need to reconsider the frequency of these types of “city-buster” impacts.
Time-lapse Monitoring in Single Boreholes Using Electrical Resistivity Tomography
Authors: Tsourlos Panagiotis , Ogilvy Richard , Meldrum Philip , Williams Geoffrey
Published: September 2009

Electrical Resistivity Tomography (ERT) has been applied in single boreholes to study leachate generation within a disused and unconfined landfill. Several boreholes were drilled in the landfill to characterize the waste and to establish the concentration and spatial variability of the leachate. To assist this study, six of these boreholes were instrumented by installing an electrode array on the outside of the PVC casing prior to completion. Resistivity measurements were taken every month from December 1999 to November 2000 to monitor the seasonal hydrochemical changes in the Chalk immediately beneath the landfill base. The results have been modelled using a novel reconstruction scheme tailored to the requirements of single-hole data. Apart from the expected matrix infiltration, the results suggest that contaminant transport in the Chalk may also occur as transient pulses in narrow fractures, when the waste is re-activated by changing groundwater levels. The study highlights the advantages of a volumetric imaging technique such as ERT to complement and optimise hydrochemical sampling.
Specific Depth Cone Resistivity Measurements to Determine Soil Engineering Properties
Authors: Daniel Chris R. , Campanella R. G. (Dick) , Howie John A. , Giacheti Heraldo L.
Published: September 2009

The University of British Columbia (UBC) began performing piezocone penetration tests (CPTU) with electrical resistivity measurements (RCPTU) in 1989. Since then, RCPTU research at UBC has focused on obtaining geo-environmental parameters such as fluid resistivity and soil engineering properties such as porosity and degree of saturation from measurements of bulk soil electrical resistivity using the empirical relationship proposed by Archie (1942). Within this framework, the paper illustrates and discusses important design and calibration issues for resistivity modules such as the use of isolated circuitry to achieve linear calibrations over large ranges of resistivity. The suitability of RCPTU measurements for determination of geo-environmental and geotechnical parameters are assessed using typical ranges of soil and groundwater properties and methods of isolating individual factors for study are discussed. Illustrative examples of RCPTU research efforts including the environmental-characterization of mine tailings, delineation of saline water intrusions in fresh water aquifers and the quality control of geotechnical ground densification are presented throughout the text. It is shown that groundwater temperature and hence ion mobility is not significantly altered by frictional heat generated during piezocone penetration and that ratio-based approaches to monitoring soil porosity can be used to eliminate the requirement for extensive groundwater sampling programs. Lastly, it is shown that RCPTU measurements above the water table can only be made using resistivity modules that are stable over a large range of resistivities and that such measurements are the most difficult to interpret because of grain surface conduction effects and generally unknown fluid resistivities.
Recommendation for New Terminology for Linearly Polarized Components of Ground Penetrating Radar Waves
Authors: Jordan Thomas E. , Baker Gregory S.
Published: September 2009

This paper presents terminology recommendations for linearly polarized electromagnetic (EM) wave components of ground penetrating radar (GPR) that are based on analogies to seismic reflection methods. These recommendations draw on the similarity of a propagating GPR wave to shear-wave seismic reflection propagation. Analogies of EM wave propagation to elastic wave propagation is not a new concept and has been previously presented in publications such as Hasdell (1995). This paper briefly discusses these analogies to form a basis for our suggested terminology change.
MESSAGE FROM THE EDITOR
Authors: Nyquist Jonathan
Published: September 2009

This is my last issue as Editor of the Journal of Environmental and Engineering Geophysics (JEEG). A new JEEG Editor—Jonathan Nyquist—has already been appointed, and he is now heavily involved in getting the next issue ready to go to press. For those of you who are not already aware, the next issue of JEEG is a special issue covering topics in ground-penetrating radar.
An Overview of Synthetic-Aperture Image Reconstruction Algorithms for GPR Imaging with Pulse-Echo and Step-Frequency FMCW Systems
Authors: Lee Hua
Published: September 2009

The ground-penetrating radar (GPR) systems currently deployed in field applications can be classified into two major types, pulse-echo and step-frequency frequency modulated continuous-wave (FMCW) devices, corresponding to the distinct features of the illumination waveforms. With the addition of synthetic-aperture scans, both versions can be directly applied to high-resolution tomographic imaging. This paper presents the tomographic image reconstruction algorithms for these two operating modalities based on one single framework of backward propagation image formation. In addition to the theoretical analysis and mathematical modeling, this paper presents the algorithm structures for both types of systems as well as results from full-scale field experiments.
Local Plane-Wave Imaging of GPR Data
Authors: Hamran Svein-Erik , Lecomte Isabelle , Gelius Leiv J.
Published: September 2009

Local Plane-Wave processing is used to image synthetic Ground Penetrating Radar (GPR) data in a non-homogeneous background. Numerically calculated Green’s functions are used to back propagate the data down to a Green’s function node in the center of the region to be imaged. From the Green’s function node a plane-wave approximation is used to propagate the data over a local image. The local images are compared with images obtained from diffraction stack processing. The effect of the irregular wavenumber sampling on the point spread function is illustrated. The local image using all corrections shows a great reduction in image distortion compared to diffraction stack processing.
Introduction to this Special Issue of JEEG
Authors: Koppenjan Steven K. , Lee Hua
Published: September 2009

This Special Issue of The Journal of Environmental and Engineering Geophysics contains 11 expanded papers originally presented at the Ninth International Conference on Ground Penetrating Radar (GPR 2002). This conference was held in Santa Barbara, California, USA from April 29–May 2, 2002 and was hosted by the University of California, Santa Barbara and Bechtel Nevada. It continued the biennial series of international scientific symposia devoted to the development of GPR. Engineers, scientists and end users from 21 countries presented 132 papers on the most recent research and case studies. GPR 2002 exhibited the importance that GPR technology now plays in solving geophysical, geotechnical and environmental problems.
Ground Penetrating Radar Soil Suitability Maps
Authors: Doolittle James A. , Minzenmayer Fred E. , Waltman Sharon W. , Benham Ellis C.
Published: September 2009

The performance of ground-penetrating radar (GPR) is dependent upon the electrical conductivity of soils. Soils having high electrical conductivity rapidly attenuate radar energy, restrict penetration depths, and severely limit the effectiveness of GPR. Factors influencing the electrical conductivity of soils include the amount and type of salts in solution and the clay content. Data on the clay and soluble salt contents of soils were used to develop thematic maps showing at different scales the relative suitability of soils for GPR applications. The United States Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS) bases these maps on field experience and soil attribute data contained in the State Soil Geographic (STATSGO) and the Soil Survey Geographic (SSURGO) databases. Attribute data used to determine the suitability of soils include clay content, electrical conductivity, sodium absorption ratio, and calcium carbonate content. Each soil attribute was rated and assigned a value ranging from 1 to 10. These attribute values were summed and the most limiting (maximum) layer indices within depths of 1.0 or [Formula: see text] were selected to represent soil components. The dominant component value was selected as the GPR suitability index for each map unit. The GPR indices are displayed in graduated color maps. The STATSGO database was used to produce the Ground-Penetrating Radar Soil Suitability Map of the Conterminous United States. This map can be used to assess the relative appropriateness of GPR for soil investigations within comparatively large areas of the conterminous United States. The SSURGO database, which contains the most detailed level of soil mapping and information provided by the USDA-NRCS, can be used to produce larger scale maps showing more varied and intricate soil patterns that influence the effectiveness of GPR within selected soil survey areas.
GPR Pulse Attenuation in a Fine-Grained and Partially Contaminated Formation
Authors: Arcone Steven A. , Delaney Allan J. , Peapples Paige
Published: September 2009

We have determined attenuation rates and relative dielectric permittivities of a fine-grained sediment formation, part of which was contaminated by hydrocarbons. Our purpose was to test previous laboratory documentation of the effects of probable adsorption and∕or capillary tension on the electrical properties of water at a common ground-penetrating radar center frequency of [Formula: see text]. The formation is a saturated, and dense glacio-marine diamicton that had a small area partially contaminated by jet fuel. Surface and trench observations showed saturation near 30% by volume, uniform and high density, resistivity at [Formula: see text], and a total hydrocarbon content of less than 0.1% within a small zone. The local hydrocarbon contamination and a spatial gradient in grain size allowed the possibility of seeing if an increase of adsorbed water and∕or relief of capillary tension within interstitial water affected the attenuation rates. We calculated the rates from the amplitude decay of ground surface wave pulses within a series of WARR (moveout) profiles recorded along a single transect. Our rates of [Formula: see text] in the coarser-grained and contaminated zone can be accounted for by the resistivity values, while those of [Formula: see text] in the uncontaminated and finer-grained zone require additional dielectric loss. The relative permittivities varied from about 17 to 22, for which modeling strongly suggests a free water value of dielectric permittivity throughout despite the fine grain content, with a mild trend toward lower values in the finer-grained zone. A strong correlation was found between attenuation rates and clay content, and only a weak correlation with hydrocarbon content. An empirical mixing theory suggests that a [Formula: see text] relaxation frequency can explain the attenuation rates in the uncontaminated zone and that DC resistivity alone falls far short of predicting the correct rates. The hydrocarbon content analysis suggests that if a threshold level for the hydrocarbon attenuation effect exists, it is not higher than about [Formula: see text]. In addition, offset surveys appear to be a useful field approach for measuring field attenuation rates.
Accuracy and Reproducibility of Mapping Surface Soil Water Content with the Ground Wave of Ground-Penetrating Radar
Authors: Huisman J. A. , Bouten W.
Published: September 2009

Ground-penetrating radar (GPR) is an attractive technique for the non-destructive measurement of soil water content. In this paper we investigated the accuracy of volumetric water content measurements with the ground wave of GPR. In particular, we 1) examined the influence of equipment in the vicinity of the GPR antennas on the data quality and 2) compared two methods to calculate soil permittivity from the arrival time of the air and ground wave. The first method assumes that the air wave and ground wave arrive simultaneously at zero antenna offset, whereas the second method includes a correction for a time shift in arrival time at zero antenna offset. We tested the influence of the equipment on the radar by introducing the different components (e.g., sleds, odometer and vehicle to pull equipment) stepwise. The results showed that the use of sleds caused a decrease in the amplitude of the ground wave. The presence of the sleds also changed the pulse shape of the air and ground wave and caused disturbances in the air wave. However, the data quality after the addition of all components was sufficient to allow automatic picking of arrival times by standard GPR software. The importance of the time shift at zero antenna offset was assessed with 20 duplicate WARR measurements measured along a [Formula: see text] transect and a sensitivity analysis based on GPR simulations. The results showed that: 1) there was a mean time shift at zero offset of [Formula: see text] that could not be explained from the GPR simulations and 2) there was a large variation in time shift at zero offset that could be explained by considering time picking error, positional error and soil water content heterogeneity in the sensitivity analysis. We conclude that a time shift correction in the calculation of soil permittivity would improve absolute soil water content measurements with GPR, but it should be noted that the large variation in time shifts makes it difficult to accurately estimate the mean time shift at zero offset.
Forensic Application of FM-CW and Pulse Radar
Authors: Freeland Robert S. , Miller Michelle L. , Yoder Ronald E. , Koppenjan Steven K.
Published: September 2009

Ground-penetrating radar (GPR) technology has supplied vital assistance in criminal investigations. However, law enforcement personnel desire further developments such that the technology is rapidly deployable, and that it provides both a simple user interface and sophisticated target identification. To assist in the development of target identification algorithms, our efforts involve gathering background GPR data for the various site conditions and circumstances that often typify clandestine burials. For this study, forensic anthropologists established shallow-grave plots at The University of Tennessee Anthropological Research Facility (ARF) that are specific to GPR research. These plots contain donated human cadavers lying in various configurations and depths, surrounded by assorted construction material and backfill debris. We scanned the plots using two GPR technologies: (1) a multi-frequency synthetic-aperture FM-CW radar [Formula: see text] (GPR-X) developed by the U.S. Department of Energy’s Special Technologies Laboratory (STL), Bechtel Nevada (Koppenjan et al., 2000), and (2) a commercial pulse radar (SIR-20) manufactured by Geophysical Survey Systems, Inc. (400 and [Formula: see text]) (GSSI). The sweep-frequency data show the large biological mass decomposing within the torso as encircled “hot spots.” The [Formula: see text] pulse radar exhibit major horizontal reflectors above the body, with shadow reflectors (horizontal multiples) occurring beneath the body at [Formula: see text] depth. The [Formula: see text] antenna was able to discern the grave walls and folded tarp covering the lower body. Under these moist, clay-rich conditions, the [Formula: see text] antenna was able to penetrate slightly beyond [Formula: see text] beneath the concrete layer. However, neither system was able to penetrate beyond a one meter depth in the moist, clay-rich soil (fine, mixed, thermic Typic-Paleudalf). Example scans from each system are provided, along with a discussion of the survey protocol and general performance.
Time-Lapse Airborne EM Surveys Across a Municipal Landfill
Authors: Beamish David , Mattsson Annina
Published: September 2009

In contrast to the majority of historical landfills, modern municipal landfills are highly engineered and follow a contain and seal strategy of leachate management. The purpose of the management system is to render the waste products inert and environmentally safe. A requirement for monitoring and assessment of the installation on the scale of decades is a consequence of the strategy. Data obtained from two repeated fixed-wing airborne electromagnetic surveys across an active, municipal solid waste landfill are considered here. The time interval between the surveys is [Formula: see text]. In theory such data may be used to both test the isolation performance of the installation and to monitor mass (leachate) transport behaviour within the landfill structure. Single frequency [Formula: see text] data obtained at a similar density ([Formula: see text] flight line spacing) over the [Formula: see text] span are presented and compared. These data have an expected mean depth of investigation of about [Formula: see text] within the landfill. Half-space conductivity models are determined from the survey data by an inversion procedure. Conductivities within the landfill are observed to be three orders of magnitude above background. From the initial survey data, a specific distribution of high conductivity material can be identified in three of the landfill cells (peak values of [Formula: see text]). Four years later, a considerable redistribution of material is apparent in the results obtained across two of the cells (peak values of [Formula: see text]). A third cell shows no change. A subtraction of the two time-lapse conductivity models allows the dynamic components of the conductivity distribution (all increases with time) to be mapped within individual cells. All larger conductivity increases [Formula: see text] are confined to the operational landfill.
Time-Domain Electromagnetic Resistivity Mapping of a Fjord-Head Delta
Authors: Best Melvyn E. , Gutsell Jeff , Clague John J.
Published: September 2009

An electromagnetic (EM) survey was conducted on the Zeballos River delta, approximately [Formula: see text] north of Victoria, British Columbia, to determine whether EM methods can help delineate the three-dimensional architecture of a fjord-head delta. The EM data were collected using a Geonics EM-47 system with a [Formula: see text] transmitter loop. The data were downloaded and subsequently edited and interpreted using the TEMIXGL layered earth inversion package from Interpex. The interpretation provided a picture of the three-dimensional resistivity structure of the delta. Throughout most of the surveyed area, a relatively thick layer of resistive [Formula: see text] sediment (gravel and sand—delta topset and foreset) overlies more conductive [Formula: see text] sediment (silt and clay—delta bottom-set), which in turn overlies resistive [Formula: see text] bedrock. Shallow sediments in the intertidal zone are saturated with sea water and hence are very conductive. However, we were able to determine the depth to more resistive (fresh water) gravel and sand and, in some areas, what we interpret to be resistive bedrock. The results of this study indicate that EM resistivity surveying can provide constraints on sediment type and thickness which, when used in conjunction with geological mapping and borehole logs, help improve our understanding of the three-dimensional architecture of these deltas.
Remote Monitoring of Leaks in Storage Tanks using Electrical Resistance Tomography: Application at the Hanford Site
Authors: Daily William , Ramirez Abelardo , Binley Andrew
Published: September 2009

A field experiment was performed to evaluate the performance of electrical resistance tomography (ERT) to detect leaks from metal underground storage tanks. The test was carried out under conditions simulating those expected during actual remediation of a single shell tank located at the U. S. Department of Energy Hanford Reservation, Washington. A system was developed for the experiment to allow remote operation during the entire test. Approximately [Formula: see text] of concentrated sodium thiosulfate (simulating tank waste) were episodically released from a steel tank in a blind test lasting [Formula: see text] (no knowledge of the release episodes during the course of the test were provided). ERT data were collected using an array of point electrodes installed in boreholes around the tank. Each day during the test a leak or no-leak condition was declared based solely on analysis of the electrical data. The success rate of the declarations made during the test was only 57%, however, further analysis carried out at the end of the test resulted in a significant improvement of the success rate. The results suggest that ERT, used either with custom built electrode arrays or existing steel cased wells, can provide an effective means of monitoring remediation or long-term integrity of underground storage tanks.
Delineating Recharge to a River Valley Aquifer by Riverine Seismic and EM Methods
Authors: Butler Karl E. , Nadeau Jean-Christophe , Parrott Russell , Daigle Annie
Published: September 2009

The City of Fredericton, New Brunswick, Canada operates a water well field adjacent to the Saint John River. Water is extracted from a semi-confined aquifer that consists of a buried sand and gravel esker ridge discontinuously covered by a clay∕silt aquitard. Geological, hydrogeochemical, and hydraulic data have long pointed to infiltration of river water as the main source of aquifer recharge but the shape and size of the recharge zone has, until recently, remained speculative. A combination of three geophysical surveys, including resistivity imaging along the shoreline, and seismic and electromagnetic profiling on the river itself, have now revealed the complex outline of the area beneath the river where the infiltration likely occurs. Broadband seismic reflections, with dominant frequencies of [Formula: see text] were recorded from depths as great as [Formula: see text] using a boomer source and 1KB Seistec line-in-cone receiver well suited to operation in the shallow water environment. EM31 and EM34 terrain conductivity meters, deployed in an outboard-motor-powered canoe and raft, revealed the subsurface conductivity structure in the same depth range. While the seismic method imaged the clay aquitard stratigraphy including its termination against the esker ridge, the electromagnetic method provided a more complete plan view of the extent of the clay window recharge zone. The two riverine data sets are highly complementary; as a start towards joint interpretation, we introduce the concept of bathymetry-corrected apparent conductivity and show how it helps to sharpen the boundary of the inferred recharge area. Confirmation of the geophysical interpretation is provided by the presence or absence of aquitard material in boreholes that have recently been drilled from a barge on the river.
An Effective Electrode Configuration for the Detection of DNAPLs with Electrical Resistivity Tomography
Authors: Goes B. J. M. , Meekes J. A. C.
Published: September 2009

Locating Dense Non-Aqueous Phase Liquids (DNAPLs) is often a bottleneck for the successful remediation and∕or control of polluted sites. Electrical Resistivity Tomography (ERT) between boreholes can detect DNAPLs because of their high electrical resistivity. In applying ERT the definition of the ‘best’ measurement schedule is a poorly resolved problem. In two case studies, and with synthetic modeling, the cross-hole tripole-pole electrode configuration is compared with the more widely used circulating dipole-dipole and cross-hole dipole-dipole electrode configurations. The case studies involved ERT measurements between five boreholes at two polluted sites with unconsolidated sediments in the Netherlands. The outcome of the modeled data and the field data show that a cross-hole tripole-pole electrode configuration is more effective in locating DNAPLs than the other configurations. The tomographic image from the cross-hole tripole-pole configuration shows clear horizontal patterns that are in accordance with the sediment layers of the subsoil. The locations of the DNAPLs as indicated by the ERT measurements have been confirmed with groundwater samples. Still, the interpretation of the tomographic images should be done with care because ERT cannot distinguish DNAPLs from other high resistivity objects (e.g., massive building blocks) and in the top of some of the images high-resistivity computational artifacts are present that could be mistaken for DNAPLs. An important practical advantage of the cross-hole tripole-pole configuration is that the number of measurement points, and thus the measurement time, is less than half that of the other configurations.
Autonomous Monitoring of Fluid Movement Using 3-D Electrical Resistivity Tomography
Authors: LaBrecque Douglas J. , Heath Gail , Sharpe Roger , Versteeg Roelof
Published: September 2009

The electrical resistivity tomography method (ERT) is seeing increasing use in long-term monitoring. Applications might include monitoring of advanced remediation methods, vadose zone fluid-flow monitoring, and monitoring below tanks at the Hanford reservation. For this method to be cost effective, future systems will need to be highly automated. This paper compares different strategies for collecting three-dimensional (3-D) data sets. We discuss the critical design aspects of the system and the importance of using integrated hardware for data collection, and software for data interpretation. An autonomous acquisition system was used to monitor a field experiment at the Idaho National Engineering and Environmental Laboratory. The system was successful at collecting data that were used to monitor infiltration of water into interbedded sediment and basalt layers. The results showed the advantages of autonomous systems for collecting data, and the need for robust operating systems designed specifically for autonomous operation.
Parametric Forms and the Inductive Response of a Permeable Conducting Sphere
Authors: Smith J. Torquil , Morrison H. Frank , Becker Alex
Published: September 2009

At early time, the time derivative of the response of isolated conductive bodies to step function excitation decays as [Formula: see text] (under a quasi-static approximation). One simple parametric form for the response with correct early time behaviour is [Formula: see text]. For a conducting magnetic sphere, parameter values are determined from the high and low frequency limit responses, together with two time scales taken from the form of the analytic solution. Parameters [Formula: see text] and [Formula: see text] correspond to transition times, for transition from an early time [Formula: see text] derivative response, and to late time exponential decay. For conducting spheres with high permeability, increasing the permeability moves the transition from early time behaviour earlier in inverse proportion to the relative permeability [Formula: see text], and increases the time constant of the late time decay in proportion to [Formula: see text]. Magnitude parameter [Formula: see text] corresponds to the difference between high frequency and low frequency limit responses.
Solid‐State NMR Investigations of the Unusual Effects Resulting from the Nanoconfinement of Water within Amphiphilic Crosslinked Polymer Networks
Authors: Ohashi Ryutaro , Bartels Jeremy W. , Xu Jinqi , Wooley Karen L. , Schaefer Jacob
Published: September 2009

Two types of solid‐state 19F NMR spectroscopy experiments are used to characterize phase‐separated hyperbranched fluoropolymer–poly(ethylene glycol) (HBFP–PEG) crosslinked networks. Mobile (soft) domains are detected in the HBFP phase by a rotor‐synchronized Hahn echo under magic‐angle spinning conditions, and rigid (hard) domains by a solid echo with no magic‐angle spinning. The mobility of chains is detected in the PEG phase by 1H → 13C cross‐polarization transfers with 1H spin‐lock filters with and without magic‐angle spinning. The interface between HBFP and PEG phases is detected by a third experiment, which utilized a 19F → 1H–(spin diffusion)–1H → 13C double transfer with 13C solid‐echo detection. The results of these experiments show that composition‐dependent PEG inclusions in the HBFP glass rigidify on hydration, consistent with an increase in macroscopic tensile strength.
Polymer‐Controlled Crystallization of Unique Mineral Superstructures
Authors: Chen Shao‐Feng , Zhu Jian‐Hua , Jiang Jun , Cai Guo‐Bin , Yu Shu‐Hong
Published: September 2009

The origin of complex superstructures of biomaterials in biological systems and the amazing self‐assembly mechanisms of their emergence have attracted a great deal of attention recently. Mimicking nature, diverse kinds of hydrophilic polymers with different functionalities and organic insoluble matrices have been designed for the morphogenesis of inorganic crystals. In this Research News, emerging new strategies for morphogenesis and controlled crystal growth of minerals, that is, selective adsorption and mesoscale transformation for highly ordered superstructures, the combination of a synthetic hydrophilic polymer with an insoluble matrix, a substrate, or the air/solution interface, and controlled crystallization in a mixed solvent are highlighted. It is shown that these new strategies can be even further extended to morphogenesis and controlled crystallization of diverse inorganic or inorganic–organic hybrid materials with structural complexity, structural specialties, and improved functionalities.
Identification of molecular targets associated with transformed diffuse large B cell lymphoma using highly purified tumor cells
Authors: Andréasson Ulrika , Dictor Michael , Jerkeman Mats , Berglund Mattias , Sundström Christer , Linderoth Johan , Rosenquist Richard , Borrebaeck Carl A. K. , Ek Sara
Published: September 2009

Follicular lymphoma (FL) frequently transforms into the more aggressive diffuse large B cell lymphoma (DLBCL‐tr), but no protein biomarkers have been identified for predictive or early diagnosis. Gene expression analyses have identified genes changing on transformation but have failed to be reproducible in different studies, reflecting the heterogeneity within the tumor tissue and between tumor samples. Gene expression analyses on Affymetrix Human Genome U133 Plus 2.0 arrays were performed, using flow cytometry sorted tumor cells derived from FL and transformed DLBCL. To identify molecular targets associated with the transformation, subsequent immunohistochemistry (IHC) analyses of the corresponding proteins were performed. Using highly purified cells, this study identified 163 genes, which were significantly deregulated during the transformation in a majority of cases. Among the upregulated transcripts, 13 genes were selected for validation using IHC, based on the availability of commercial antibodies, and galectin‐3 and NEK2 proteins specifically identify DLBCL‐tr, when compared with FL. We demonstrate that by purifying tumor cells through cell sorting, thereby reducing the heterogeneity due to infiltrating cells, it was possible to identify distinct differences between tumor entities rather than variations due to cellular composition. Galectin‐3 and NEK2 both identified a subgroup of DLBCL‐tr, and the function of these protein markers also suggests a biological role in the transformation process. Am. J. Hematol. 2009. © 2009 Wiley‐Liss, Inc.