bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Bioattenuation in the Management of Aromatic Hydrocarbon Plumes in Aquifers
Authors: Salanitro Joseph P. 
Published: February 2007

AbstractGround water scientists have made significant advances in understanding the soil interactions, hydrogeology, fate and transport, and subsurface microbiology of aromatic hydrocarbons (BTEX) in aquifer systems. It is now generally recognized that a major factor responsible for the attenuation and mass reduction of BTEX in plumes is the widespread occurrence of hydrocarbon biodegradation by indigenous soil microorganisms in aquifer material. Most well‐studied BTEX plumes that develop from the accidental release of gasoline fuels contain low levels of soluble hydrocarbons (< 1 to 5000 ppb) and have been shown to be spatially confined because of natural biotransformation mechanisms. These in situ processes are controlled by source and aquifer characteristics, permeability, sorption, and geochemical properties of the aquifer. Many laboratory subsoil‐ground water microcosms and field studies (10 to 20 C) have demonstrated the rapid biodecay (1 to SO percent/day for microcosms and 0.5 to 1.5 percent/day for plumes) of these aromatic compounds under primarily aerobic conditions (i.e., those with sufficient dissolved oxygen). The ability to implement ground water bioremediation will depend upon our understanding of source control and aquifer recharge effects on the spatial distribution of plumes. In addition, estimating the biodegradation of sorbed BTEX, determining limits and potential for in situ biostimulation of soluble plumes, and establishing data requirements for predictive modeling of natural attenuation will be useful for this remediation technology. The use of these tools to manage ground water quality appears to represent the most practical alternative, particularly for low‐risk ground water supplies.
Hazardous Waste Remediation: A 21st Century Problem
Authors: Bredehoeft J.D. 
Published: February 2007

AbstractThe United Stales, both the private and the public sector, is currently spending approximately $10 billion annually on environmental cleanup. In 1991. the Waste Management Research and Educational Institute at the University of Tennessee, Knoxville completed an exhaustive study that estimated if we continue to pursue current policies the total cost of the cleanup will be approximately $750 billion — in 1990 dollars. This suggests that given current technology and the current rate of expenditure, cleanup will take 75 years ‐ well into the latter half of the next century.The legacy of environmental problems associated with our weapons complex is enormous. The Tennessee group estimated that one‐third of the total cost of cleanup — approximately $240 billion — will be borne by the Department of Energy (DOR). Currently, approximately one‐half of the annual expenditures for cleanup conies from DOE —$5 billion, one‐third of the DOE budget.In contrast, the amount of funds for basic research on environmental cleanup problems is small. The federal government spends less than $100 million annually for basic research — less than 1 percent of the total annual expenditure of $10 billion. This level of funding for basic research seems shortsighted given the current status of cleanup technologies and the expected long duration of the problem.
Enhanced Degradation of Dissolved Benzene and Toluene Using a Solid Oxygen‐Releasing Compound
Authors: Bianchi‐Mosquera Gino C. , Allen‐King Richelle M. , Mackay Douglas M. 
Published: February 2007

AbstractA field lest to evaluate the applicability of an oxygon‐releasing compound (ORC) to the rernediation of ground water contaminated with benzone and toluene was conducted in the Borden Aquifer in Ontario. Canada. Benzene and toluene were injected as organic substrates to represent BTEX compounds, bromide was used as a tracer, and nitrate was added to avoid nitrate‐limited conditions.The fate of the solutes was monitored along four lines of monitoring points and wells. Two lines studied the behavior of the solutes upgradient and downgradient of two large‐diameter well screens filled with briquets containing ORC and briquets without ORC. One line was used to study the solute behavior upgradient and downgradient of columns of ORC powder placed directly in the saturated zone. The remaining line was a control.The results indicate that ORC in both briquet and powder form can release significant amounts of oxygen to conlaminated ground water passing by it. In the formulation used in this work, oxygen release persisted for at least 10 weeks. Furthemiore, the study indicates that the enhancement of the available dissolved oxygen content of at least 4 mg/L each of the ground water by ORC can support biodegradation of benzene and toluene dissolved in ground water. Such concentrations are typical of those encountered at sites contaminated with petroleum hydrocarbons; therefore, these results suggest that there is promise for ORC to enhance in situ biodegradation of BTKX contaminants at such sites using passive (nonpumping) systems to contact the contaminated ground water with the oxygen source.
A Simple Method for Measuring the Vertically of Small‐Diameter Driven Wells
Authors: Kjeldsen Peter , Skov Bent 
Published: February 2007

AbstractThe presence of stones, solid waste, and other obstructions can deflect small‐diameter driven wells during installation, leading to deviations of the well from its intended position. This could lead to erroneous results, especially for measurements of ground water levels by water level meters. A simple method was developed to measure deviations from the intended positions of well screens and determine correction factors required for proper measurement of ground water levels in nonvertical wells. The method is based upon measurement of the hydrostatic pressure in the bottom of a water column, which is established in the well lube. The method was used to correct water level measurement in wells driven through a landfill site. Errors of up to 27 cm in water level were observed at the landfill site. The correction of the water level measurements had a significant effect on estimated local ground water flow directions.
Characterization of Chromium‐ Contaminated Soils Using Field‐Portable X‐Ray Fluorescence
Authors: Puls Robert W. , Clark Donald A. , Carlson Clark , Vardy James 
Published: February 2007

AbstractA detailed characterization of the underlying and adjacent soils near a chrome plating shop utilized field‐portable X‐ ray fluorescence (XRF) as a screening tool. XRF permitted real‐time acquisition of estimates for total metal content of soils. A trailer‐mounted soil coring unit was used to recover soil samples for XRF analyses. This approach minimized the number of samples required for adequate characterization of the chromium distribution in the soils at the site and permitted immediate delineation of source‘hot spots.’The nondestructive nature of the XRF analyses permitted correlation analysis using inductively coupled plasma (ICP) techniques. Correlation between XRF and ICP was very good (r2= 0.95) but the XRF analyses underestimated the total chromium concentrations, probably because of inappropriate calibration samples.
Considerations for the Design of In Situ Vapor Extraction Systems: Radius of Influence vs. Zone of Remediation
Authors: Johnson Paul C. , Ettinger Robert A. 
Published: February 2007

AbstractWhen designing in situ soil vapor extraction systems, the number and placement of vapor extraction wells arc typically based on the radius of influence determined from some combination of pilot test data, theoretical considerations, and experience. In this report, we examine common methods used to determine the radius of influence, and through examples we illustrate how effective this remedial design approach is. Significant conclusions arc the following: (a) systems designed by radius of influence‐based approaches may never achieve desired remedial goals: (b) systems designed by radius of influence‐based approaches may result in longer operation times and higher total costs than a system that incorporates remedial goals and some level of fundamentally based predictive modeling: and (c) at best, the radius of influence‐based approach ensures containment of contaminant vapors.
Cone Penetrometer Testing and Discrete‐Depth Ground Water SamplingL Techniques: A Cost‐Effective Method of Site Characterization in a Multiple‐Aquifer Setting
Authors: Zemo Dawn A. , Pierce Yvonne G. , Gallinatti John D. 
Published: February 2007

AbstractCone penetromcler testing (CPT). combined with discrete‐depth ground water sampling methods, can significantly reduce the time and expense required to characterize large sites that have multiple aquifers. Results from the screening site characterization can then be used to design and install a cost‐effective monitoring well network. At a site in northern California, it was necessary to characterize the stratigraphy and the distribution of volatile organic compounds (VC)Cs) to a depth of 80 feet within a ½‐mile‐by‐½‐mile residential and commercial area in a complex alluvial fan setting. To expedite characterization, a five‐week field screening program was implemented that consisted of a shallow ground water survey, CPT soundings and pore‐pressure measurements, and discrete‐depth ground water sampling. Based on continuous lithologic information provided by the CPT soundings, four predominantly coarse‐grained, water yielding stratigraphic packages were identified. Individual coarse‐grained units within each package are discontinuous, as they coalesce and pinch out in longitudinal and transverse directions. Seventy‐nine discrete‐depth ground water samples were collected using either shallow ground water survey techniques, the BAT Enviroprobe, or the QED HydroPunch I, depending on subsurface conditions.Using results from these efforts, a 20‐well monitoring network was designed and installed to monitor critical points within each stratigraphic package. Good correlation was found for hydraulic head and chemical results between discrete‐depth screening data and monitoring well data. Understanding the vertical VOC distribution and concentrations produced substantial time and cost savings by minimizing the number of permanent monitoring wells and reducing the number of costly conductor casings that had to be installed. Additionally, significant long‐term cost savings will result from reduced sampling costs, because fewer wells comprise the monitoring network. We estimate these savings to be 50 percent for site characterization costs, 65 percent for site characterization time, and 60 percent for long term monitoring costs.
Low‐Cost On‐Site Treatment of Landfill Leachate Using Infiltration Beds: Preliminary Field Trial
Authors: Robertson W.D. , Murphy A.M. , Cherry J.A. 
Published: February 2007

AbstractA small‐scale field experiment was carried out to demonstrate the effectiveness of using septic system ‐type infiltration beds for on‐site treatment of landfill leachate. Using an infiltration bed with a 3‐m‐thick vadose zone of medium sand, and loaded at a rate 01 18 cm/day, a treatment efficiency of >99 percent was obtained for Fe, 94 percent for NH4+, and 54 percent for dissolved organic carbon (DOC). Attenuation occurred during one‐ to two‐day residency in the aerobic vadose zone (pore gas O2 > 12 percent by volume) as a result of oxidation reactions that caused nitrification of NH4+, convened Fe2+ to Fe3+ allowing subsequent precipitation of sparingly soluble Fe oxyhydroxide minerals, and biodegraded DOC. Attenuation of an aerobically degradable trace volatile organic compound (dichlorobenzene) was also noted, although other less degradable compounds (trichloroethylene and tetrachloroethylene) persisted.Fe mineral precipitation caused a discontinuous hardpan layer to occur in the zone immediately below the infiltration pipes. However, this layer did not become impermeable or continuous enough to significantly impede infiltration during the 82‐day experiment.Advantages of this technology for leachate treatment are that it is low cost, it is simple to construct and operate. and treatment occurs on‐site, avoiding the cost of transporting leachate off‐site for treatment.
An Evaluation of Soil‐Gas Surveying for H2S for Locating Subsurface Hydrocarbon Contamination
Authors: Robbins Gary A. , McAninch Brian E. , Gavas Francis M. , Ellis Patricia M. 
Published: February 2007

AbstractA soil‐gas survey was conducted at a gasoline service station and a former fire training facility to determine if surveying for hydrogen sulfide could be useful in locating nonaqueous phase hydrocarbon fuel in the subsurface. Relative; to total organic vapor, oxygen, and carbon dioxide distributions, detectable hydrogen sulfide concentrations were much more restricted to the suspected source vicinity at both sites. Appreciable levels of soil‐gas hydrogen sulfide. up to 600 Vppb. were observed in areas characterized by anaerobic or microaerophilic conditions having bulk oxygen levels below 4 percent. Based on the hydrogen sulfide distribution, nonaqueous phase hydrocarbon fuel was located at each site. These results suggest that soil‐gas surveying for hydrogen sulfide may help locale mobile or residual gasoline and other nonaqueous phase hydrocarbons in the subsurface.
Field Comparison of Analytical Results from Discrete‐Depth Ground Water Samplers
Authors: Zemo Dawn A. , Delfino Thomas A. , Gallinatti John D. , Baker Virgil A. , Hilpert Laurence R. 
Published: February 2007

AbstractDiscrete‐depth ground water samplers are used during environmental screening investigations to collect ground water samples in lieu of installing and sampling monitoring wells. Two of the most commonly used samplers are the BAT Enviroprobe and the QED HydroPunch I, which rely on differing sample collection mechanics. Although these devices have been on the market for several years, it was unknown what, if any, effect the differences would have on analytical results for ground water samples containing low to moderate concentrations of chlorinated volatile organic compounds (VOCs). This study investigated whether the discrete‐depth ground water sampler used introduces statistically significant differences in analytical results. Our goal was to provide a technical basis for allowing the two devices to be used interchangeably during screening investigations.Because this study was based on field samples, it included several sources of potential variability. It was necessary to separate differences due to sampler type from variability due to sampling location, sample handling, and laboratory analytical error. To statistically evaluate these sources of variability, the experiment was arranged in a nested design. Sixteen ground water samples were collected from eight random locations within a 15‐foot by 15‐foot grid. The grid was located in an area where shallow ground water was believed to be uniformly affected by VOCs. The data were evaluated using analysis of variance.This study indicates that when sampling for short‐chain. chlorinated aliphatic compounds such as trichloroethylene, spatial variability from sampling location (over even a relatively small area) exceeds the differences between the Enviroprobe and HydroPuneh I. Therefore, the two sampling devices can be used interchangeably without reducing the internal consistency of the resulting data. However, when sampling for chlorinated aromatics, the choice of sampling device max introduce significant differences in the analytical results.
The Hydraulic Effects of Lost Circulation and the Implications for Contaminant Migration During Drilling
Authors: Schilling Keith E. 
Published: February 2007

AbstractThe impact of lost circulation during rotary drilling near an existing monitoring well cluster was evaluated by periodic measurements of water levels and contaminant concentrations at the well cluster. Due to regulatory concerns, changes in water levels or VOC concentration in the well cluster during drilling would trigger monitoring well redevelopment. The borehole was drilled approximately 30 feet northeast of four nested monitoring wells that screen Devonian and Silurian carbonate bedrock at depths of 15, 60, 130, and 190 feet. Following complete circulation loss at depths of 177 and 1 S3 feet in the borehole, a rapid decrease in water levels was observed in the upper three monitoring wells. The water level in the well that was screened through the lost circulation zones increased slightly.Decreasing water levels in formations located above the point of circulation loss appear to occur in response to a sudden decrease in borehole fluid pressure caused by the flow of drilling fluid into the formation. The relative contribution of contaminated formation water lo the borehole can be estimated by using the time‐drawdown relationship and estimates of transmissivity. At the point of circulation loss, significant dilution of contaminant concentrations occurs from the loss of drilling fluid into the contaminated zone. Contaminated formation water entering the borehole during periods of complete lost circulation may mobilize contaminants from upper lo lower formations. Lost circulation into a formation would be signaled by a water level increase in monitoring wells. The wells would subsequently require development to remove the volume of fluid lost to the formation, including both drilling fluid and contaminated formation water. Monitoring wells exhibiting declining water levels following lost circulation would not require development since drilling water has not entered the zones screened by these wells.
A Sophisticated Ground Water Analytical Tool
Authors: Tonjes David J. , Heil James H. , Black John A. 
Published: February 2007

AbstractStiff diagrams arc a multivariate method of analysis used to describe the chemical state of ground water. The use of Stiff diagrams to describe multiconstituent contamination sites, such as landfills, has distinct advantages over single constituent analyses. Problems associated with traditional Stiff diagram analyses, such as diagram attentuation, can be addressed by allowing the scale of the diagram to vary with the ionic strength of the analyzed sample. The use of these sliding scale Stiff diagrams reveals the chemical slate of the ground water over wide ranges of constituent concentrations and thus allows for sensitive and sophisticated depictions of complicated contamination sites in a fashion that is extremely difficult to replicate with single constituent analyses. This approach has possible applications for understanding and tracing the mixing and chemical changes in uncontaminated settings.
Geophysical Characterization of Smelting Wastes: A Case History
Authors: Ellefsen Karl J. , Bochicchio Regina M. 
Published: February 2007

AbstractThe thicknesses of slag piles at a smelling site in Midvale. Utah, were determined using geophysical methods; this information was needed to estimate the cost of removing or isolating slag that has the potential to contaminate ground water. From a small‐scale preliminary investigation that, included terrain‐conductivity profiling, low‐frequency resistivity measurements, and induction logging, the electrical resistivities of the slag and the underlying sediment were determined to be approximately 100 Ω‐m and 15 Ω‐m, respectively. Because electromagnetic measurements are affected by such significant contrasts, terrain‐conductivity profiling and time‐domain electromagnetic soundings were used to determine the thicknesses of the slag piles. Generally, the estimated thicknesses from both methods were consistent and geologically plausible. In some instances, reliable estimates of the thicknesses could not be obtained because, for example, the measurements were affected by buried metal objects.In this case study, we emphasize three principles that might help investigators at other smelter sites. First, a small‐scale preliminary investigation saves time and money because those geophysical methods that have the greatest likelihood of success can be determined. Second, when the results from several geophysical methods are consistent, the confidence in the interpretation increases. Third, geophysical characterization is not always successful. Nonetheless, because of its outstanding advantages, it should be used before other more expensive characterization methods arc tried.
Stratigraphic Trapping of Spilled Jet Fuel Beneath the Water Table
Authors: Vroblesky D. A. , Robertson J. F. , Rhodes L.C. 
Published: February 2007

AbstractEnvironmental conditions and the initial attempt to recover JP‐4 jet fuel from a shallow aquifer at a tank farm in Hanahan, South Carolina, in 1975. allowed the jet fuel to become stratigraphically trapped below the water table. The trapped jet fuel remained an undetected source of dissolved hydrocarbon contamination in shallow ground water in the area for 17 years. The trapped jet fuel was located when a variety of chemical, hydrologic. geologic, and historical evidence led investigators to install and sample deeper wells. These findings emphasize the need to use an integrated approach lo evaluating the data when determining the extent of contamination and planning fuel recovery operations in a lithologically heterogeneous aquifer.
Uptake of Dissolved and Oil Phase Organic Chemicals by Bacteria
Authors: Mihelcic James R. , Pritschow Annette , Lueking Donald R. 
Published: February 2007

AbstractHydrophobic organic chemicals (HOCs) discharged into soil and ground water will partition into gaseous, aqueous, oil, and sorbed phases. Knowledge of how bacteria assimilate HOCs is important to individuals involved in evaluating intrinsic, or engineered, bioremediation. The majority of bacteria isolated from the subsurface are gram‐negative. The outer membrane of gram‐negative organisms acts as a selective barrier to many solutes, including hydrophobic chemicals. Thus, diffusional transport of a hydrophobic solute through the outer membrane may be the rate‐limiting step in biodegradation. Bacteria may also produce biosurfactants that can facilitate cell‐oil contact or assist solubilization of oil and sorbed phases.
Sampling of Agrochemicals for Environmental Assessment in Rice Paddies: Dry Tropical Wetlands, Costa Rica
Authors: Loaiciga Hugo A. , Robinson Timothy H. 
Published: February 2007

AbstractThis paper presents results from a preliminary sampling strategy developed to track agricultural contaminants found in surface and subsurface media and used commonly in rice paddy cultivation in the dry, tropical forest coastal region of Guanaeaste, Costa Rica. The emphasis is on the impact of eight indicator pesticides, five forms of nitrogen and phosphorus that are common nutrients found in fertilizers. After the field sampling strategy was developed, soil and water samples were collected twice: once during the beginning: of the wet season and once during the initiation of the dry season. Hydrological parameters, soil classifications, agricultural product toxicology, irrigation and drainage networks, cultivated areas, land ownership, and pristine environments have been studied, mapped, and entered into a database in order lo understand the spatial and temporal distribution of potential contaminants and their pending ecological degradation.Alternative crops and agricultural practices are suggested to reduce or eliminate impacts on biological preserves. Database development and basin characteristics have been entered into a Geographic Information System (GIS) that is capable of fully integrating suggested site modeling. Field sampling results indicate that proposed rice paddy cultivation in a relatively undisturbed basin is likely lo have minimal impact on downstream biological preserves.