bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uses of Chloride/Bromide Ratios in Studies of Potable Water
Authors: Davis Stanley N. , Whittemore Donald O. , Fabryka‐Martin June 
Published: August 2005

AbstractIn natural ground water systems, both chlorine and bromine occur primarily as monovalent anions, chloride and bromide. Although dissolution or precipitation of halite, biological activity in the root zone, anion sorption, and exchange can affect chloride/bromide ratios in some settings, movement of the ions in potable ground water is most often conservative. Atmospheric precipitation will generally have mass ratios between 50 and 150; shallow ground water, between 100 and 200; domestic sewage, between 300 and 600; water affected by dissolution of halite, between 1000 and 10,000; and summer runoff from urban streets, between 10 and 100. These, and other distinctive elemental ratios, are useful in the reconstruction of the origin and movement of ground water, as illustrated by case studies investigating sources of salinity in ground water from Alberta, Kansas, and Arizona, and infiltration rates and pathways at Yucca Mountain, Nevada.
Procedures for Uncertainty Analyses Applied to a Landfill Leachate Plume
Authors: Abbaspour K.C. , Schulin R. , van Genuchten M. Th. , Schlappi E. 
Published: August 2005

AbstractEnvironmental data often have features that are distinct from data in other branches of science. These features include spatial and/or temporal auto‐correlation, natural heterogeneity, measurement errors, small sample sizes, and simultaneous existence of different types and qualities of data. Realistic environmental modeling requires simulation procedures that account for all of these features. In this study, a model of uncertainty analysis, BUDA, is used to account for the noted features and provide a unified framework for quantification, propagation, and reduction of uncertainty. The BUDA model is used to analyze the development of a chloride plume around an old landfill to the year 2020. This article describes the different components of BUDA as they relate to the landfill application.
Spatial Variability in In Situ Aerobic Respiration and Denitrification Rates in a Petroleum‐Contaminated Aquifer
Authors: Schroth M.H. , Istok J.D. , Conner G.T. , Hyman M.R. , Haggerty R. , O'Reilly K.T. 
Published: August 2005

AbstractAn extensive series of single‐well, push‐pull tests was performed to quantify horizontal and vertical spatial variability in aerobic respiration and denitrification rates in a petroleum‐contaminated aquifer. The results indicated rapid consumption of injected O2 or NO3− in shallow and deep test intervals across a large portion of the site. Computed first‐order rate coefficients for aerobic respiration ranged from 0.15 to 1.69 h−1 in the shallow test interval, and from 0.08 to 0.83 h−1 in the deep test interval. The largest aerobic respiration rates occurred on the upgradient edge of the contaminant plume where concentrations of petroleum hydrocarbons and dissolved O2 were relatively high. Computed first‐order rate coefficients for denitrification ranged from 0.09 to 0.42 h−1 in the shallow test interval, and from 0.11 to 0.28 h−1 in the deep test interval. The largest denitrification rates occurred on the downgradient edge of the plume where hydrocarbon concentrations were relatively high but dissolved oxygen concentrations were small. The rates reported here represent maximal rates of aerobic respiration and denitrification, as supported by high concentrations of electron acceptors in the injected test solutions. Production of dissolved CO2 during aerobic respiration and denitrification tests provided evidence that O2 and NO3− consumption was largely due to microbial activity. Additional evidence for microbial NO3− consumption was provided by reduced rates of NO3−consumption when dissolved O2 was injected with NO3−, and by increased N2O production when C2H2 was injected with NO3−.
Characterization of an Unregulated Landfill Using Surface‐Based Geophysics and Geostatistics
Authors: Woldt Wayne E. , Hagemeister Michael E. , Jones David D. 
Published: August 2005

AbstractThis paper develops a geoelectrical and geostatistical‐based methodology that can be used to screen unregulated landfills for the presence of leachate and obtain an approximation of the vertical/spatial extent of waste. The methodology uses a surface electromagnetic (EM) survey combined with indicator kriging. Indicator kriging allows for the use of EM data that have been collected over highly electrically conductive material such as that occurring within landfills. Indicator kriging maps were generated for several vertical sections cut through a landfill to establish the landfill strata. Similarly, horizontal sections were generated to evaluate the areal extent of waste and leachate in the vadose zone and saturated zones, respectively. The horizontal and vertical maps were combined to estimate the volume of solid waste and liquid within three zones: (1) waste, (2) waste and/or leachate, and (3) potential leachate. The methodology appears hold promise in providing results that can be used as part of a hazard assessment, or to assist in the placement of monitoring wells at sites requiring additional study. A case study is used to demonstrate the methodology at an unregulated landfill in eastern Nebraska.
Review of Phosphate Mobility and Persistence in 10 Septic System Plumes
Authors: Robertson W.D. , Schiff S.L. , Ptacek C.J. 
Published: August 2005

AbstractPhosphate distribution was reviewed in 10 mature, highly monitored septic system ground water plumes in central Canada. It was shown that six plumes (primarily those on calcareous sands) of enriched P concentrations (0.5 to 5 mg/L P) exceeding 10 m in length are present. In each case, phosphate migration velocity is highly retarded (retardation factor, 20 to 100) compared to the ground water velocity, hut migration rates remain sufficiently fast (−1 m/a) to the of concern when considering long‐term operation and the normal setback distance of septic systems from adjacent surface water bodies (∼ 15 m). Much smaller scale phosphate plumes (< 3 m in length) are present at the acidic sites on noncalcareous sands and on silt‐ and clay‐rich sediments.At all of the sites, ground water concentrations are lower than effluent values by amounts ranging from 23 to 99%, suggesting that P accumulation has occurred in the vadose zone. This was confirmed by sediment analyses at four of the sites which, in each case, showed that zones of Penrichment were present within 1 m of the infiltration pipes (Wood 1993; Zanini et al. 1998). Also, observed phosphate concentrations are generally consistent with values expected based on the solubility constraints of the minerals vivianite in reducing zones (including the septic tank), and strengite and variscite in oxidizing zones, providing further evidence that min‐eral precipitation reactions play a role in limiting P concentrations. Strengite and variscite have the potential to limit P to low con‐centrations (co.1 mg/L) under acidic conditions, but oxidation of sewage efiluent leads to acidic conditions only in noncalcareous terrain or beneath old septic systems where calcium carbonate has been depleted. Overall, phosphate plume migration velocities in ground water appear to be controlled by sorption processes, but the phosphate concentrations that are present in the plumes appear to be strongly controlled by mineral precipitation reactions that occur in close proximity to the infiltration pipes.
Chloride/Bromide and Chloride/Fluoride Ratios of Domestic Sewage Effluents and Associated Contaminated Ground Water
Authors: Vengosh Avner , Pankratov Irena 
Published: August 2005

AbstractTo establish geochemical tools for tracing the origin of ground water contamination, we examined the variations of Cl/Br and Cl/F (weight) ratios in (1) domestic waste water from the Dan Region Sewage Reclamation Project and from reservoirs in the central coast of Israel; (2) associated contaminated ground water; and (3) pristine ground water from the Mediterranean coastal aquifer of Israel. Our data show that supply water, anthropogenic NaCl and fluoridation control the Cl/Br (410 to 873) and Cl/F (468 to 1070) ratios of domestic waste water, and conventional sewage treatment does not affect the anthropogenic inorganic signals. The Cl/Br ratios of ground water contaminated with sewage effluent reflect conservative mixing proportions of sewage and regional ground water components. Sensitivity tests demonstrate that it is possible to detect and distinguish sewage contamination from marine ratios after a sewage contribution of 5 to 15% is mixed with regional ground water. Mixing with Br‐enriched fresh water (e.g., Sea of Galilee; Cl/Br=145), however, would reduce this sensitivity. Since the high Cl/Br signal of sewage effluents is distinguishable from other anthropogenic sources with low Cl/Br ratios (e.g., street runoff, agriculture return flows) and from natural contamination sources (e.g., salt water intrusion; Cl/Br=293), Cl/Br ratios can therefore be a useful inorganic tracer for identification of the origin of contaminated ground water. The Cl/F ratios of sewage‐contaminated ground water (284 to 5186) were higher than those in the original sewage effluent, which suggests retention of fluoride into the aquifer solid phase.
Virus Occurrence and Transport in a School Septic System and Unconfined Aquifer
Authors: DeBorde Dan C. , Woessner William W. , Lauerman Bruce , Ball Patrick N. 
Published: August 2005

AbstractFederal efforts to establish reliable natural disinfection criteria for ground water supplies require the identification of appropriate indicator viruses to represent pathogenic viruses and an understanding of parameters affecting virus survival and transport in a variety of hydrogeologic settings. A high school septic system and the associated fecal waste‐impacted unconfined sand and gravel aquifer were instrumented to: (1) evaluate if the concentrations of enterovirus and coliphage in this system were sufficient to allow their use as indicator viruses; (2) establish viral transport rates, transport distances, and concentrations in a highly conductive cold water aquifer. Enteroviruses were found in only two of eight assays of the septic tank effluent (0.26 and 4.4 virus/L) and were below detection in eight ground water samples. Male‐specific and somatic coliphage were detectable in both the septic tank effluent (averaging 674,000 and 466,000 coliphage/L, respectively) and in the impacted underlying ground water, decreasing to detection limits beyond 38 m of the drainfield. Virus transport parameters in this aquifer were measured by seeding high numbers of MS2 and ØX174 coliphage into the ground water and documenting their transport over 17.4 m. A portion of the seeded virus traveled at least as fast as the bromide tracer (1 to 2.9 m/d). Proposed natural disinfection criteria would not be met in this aquifer using standard 30.5 m setback distances. In addition, the virus sorption processes and long survival times resulted in presence of viable seed virus for more than nine months.
KYSPILL: A Practical Modeling System of Scale‐Dependent Dispersion after Chemical Spills
Authors: Serrano Sergio E. 
Published: August 2005

AbstractScale‐dependent dispersion is a phenomenon that manifests as an increase in the magnitude of the dispersion parameters with the distance of travel, or the time after the spill. This implies that contaminant plumes occupy a larger portion of the aquifer at later times than that predicted by the traditional convection‐dispersion models. Although it is an area of active research, scale‐dependent ground water pollution modeling is now available through the practical application of a new hydrologic theory of dispersion. The KYSPILL software was developed as an application of this theory. KYSPILL provides an easy way to simulate and graph the movement of contaminant plumes in heterogeneous soils and aquifers. It has self‐supported menus and windows that allow the selection of the type of spill, the input of hydrogeologic data, and the plotting of contours and breakthrough curves. It simulates biological or radioactive decay, adsorption, point or nonpoint sources in the unsaturated zone and subsequently in the saturated zone. An automatic self‐diagnosis system tests every input data, and an on‐line, context‐sensitive, help system aids the user in the input data and running phases. KYSPILL is a simple tool for those chemical spills with little or uncertain data. It may be used for preliminary forecasting, monitoring planning, or remedial actions.
Effects of Steady‐State Assumption on Hydraulic Conductivity and Recharge Estimates in a Surficial Aquifer System
Authors: Halford Keith J. 
Published: August 2005

AbstractThe ability of a calibrated flow model to predict the behavior of a surficial aquifer system is governed by the quality of the hydraulic conductivity and recharge estimates used. Reasonable lateral and vertical hydraulic conductivities can be estimated by steady‐state simulations driven by effective recharge rates that approximate the net effects of evapotranspiration, and water released from storage during periods of recession. Results from a hypothetical, transient, cross‐sectional model indicated that most of the water was contributed uniformly from storage from five to 25 days after a recharge event. Results also showed that a steady‐state, snapshot calibration approach can be used on aquifers in a humid climate with diffusivities between 20 and 500 m2/d. Most estimates of the lateral and vertical hydraulic conductivities of the hypothetical aquifer system were within 30% of the actual values. Estimates of hydraulic conductivity from the transient cases were similar to those from the snapshot calibration cases. The long‐term recharge rate could be identified by calibrating to multiple synoptic surveys that were sampled over the range of drier to wetter conditions. The effective recharge rates estimated for the driest and wettest conditions bracketed the long‐term recharge rate. Results suggested that the effective recharge rate estimated for the synoptic survey with the lowest water level root‐mean‐square (RMS) error was the best estimate of the long‐term recharge rate. A field application of the snapshot calibration approach simulated the surficial aquifer system beneath Cecil Field Naval Air Station well and provided reasonable estimates of the long‐term recharge rate (0.4 mm/d) relative to the range of recharge rates that were independently estimated by the chloride concentration ratio method (0.2 to 0.6 mm/d).
Effects of Velocity on the Transport of Two Bacteria Through Saturated Sand
Authors: Hendry M. J. , Lawrence J. R. , Maloszewski P. 
Published: August 2005

AbstractTransport of the bacteria Klebsiella oxytoca and Burkholderia cepacia G4PR1 (G4PR1) was investigated in column experiments conducted under conditions that allowed us to quantify sorption under a range of ground water velocities. Column experiments (33 mm I.D. × 114 mm long columns) were conducted at four linear water velocities (0.5 to 14 cm.hr−1) through a medium to coarse grained silica sand. The peak C/Co concentrations for both bacteria were attenuated with respect to a conservative tracer (Cl−), and well‐defined tailing was observed. Breakthroughs of both bacteria were influenced by the water velocity. In the case of G4PR1, the attenuation of the peak C/Co concentrations increased as the velocity decreased while the peak C/Co concentrations for K. oxytoca were similar at velocities between 3 and 13 cmhr−1 but decreased at the lowest velocity tested (0.6 cm‐hr−1). The tailing reached constant C/Co values of between 2 × 10−3 and 5 × 10−3, and between 2 × 10−5 and 5 × 10−5 for K. oxytoca and G4PR1 after 2t0. A one‐dimensional mathematical model for advective‐dispersive transport that accounts for irreversible (kirr) and reversible (kf and kr) sorption was used to quantify the sorption process. Both irreversible and reversible sorption was required to obtain good fits to the measured K. oxytoca data. Results of this modeling suggested that kirr and kr are independent of velocity and an empirical relationship was developed relating kf to velocity. For G4PR1, the best fits were obtained using only reversible sorption. Results of the modeling suggested that kf was independent of velocity at all velocities tested and kr was independent of velocity at velocities between 3 and 13 cmhr−1. At the lowest velocity investigated (0.5 cmhr−1), the kf value decreased considerably. This study showed that sorption characteristics are bacteria specific, and are likely related to surface chemistry because G4PR1 is more hydrophobic than K. oxytoca. The study also showed that in order for bacterial transport experiments to be directly applicable to the subsurface, they should be conducted at velocities similar to those observed in the subsurface, or the relationship between the sorption parameter(s) and velocity should be known.
Degradation of Aromatic and Chlorinated Aliphatic Hydrocarbons in the Anaerobic Part of the Grindsted Landfill Leachate Plume: In Situ Microcosm and Laboratory Batch Experiments
Authors: Bjerg Poul L. , Riigge Kirsten , Cortsen Jesper , Nielsen Per H. , Christensen Thomas H. 
Published: August 2005

AbstractThe fate of seven aromatic and four chlorinated aliphatic compounds was studied using in situ microcosm (ISM) and laboratory batch (LB) experiments performed at six distances along a flow line in the anaerobic leachate plume downgradient of the Grindsted Landfill, Denmark. The redox conditions were dominated by iron reduction in this part of the plume (15 to 60 m downgradient of the landfill); however, methanogenesis and sulfate reduction also took place closer to the landfill (15 to 45 m). Generally, good accordance was found between the degradation of the compounds determined by the two experimental approaches, considering the limitations of the experimental periods (up to 220 days for the ISM and up to 537 days for the LB). Of the aromatic compounds, toluene, o‐ and m/p‐xylene were degraded, while benzene, ethylbenzene, and naphthalene were not degraded, neither in the ISM nor in the LB at any distance from the landfill. All the chlorinated aliphatic compounds, (TeCM, 1,1,1‐TCA, PCE, and TCE) were degrad‐able; however, the degradation potential for PCE and TCE depended on the distance from the landfill. For most compounds, both approaches gave results comparable to those of the natural gradient field injection experiment performed in the same plume. This suggests that laboratory batch experiments, which are easier to run than ISM experiments, may be a useful tool in determining the degradability of mono aromatic hydrocarbons and chlorinated aliphatic hydrocarbons under strongly anaerobic conditions in the investigation of natural attenuation in landfill leachate plumes.
Bioremediation of Petroleum Hydrocarbon‐Contaminated Ground Water: The Perspectives of History and Hydrology
Authors: Chapelle Francis H. 
Published: August 2005

AbstractBioremediation, the use of microbial degradation processes to detoxify environmental contamination, was first applied to petroleum hydrocarbon‐contaminated ground water systems in the early 1970s. Since that time, these technologies have evolved in some ways that were clearly anticipated by early investigators, and in other ways that were not foreseen. The expectation that adding oxidants and nutrients to contaminated aquifers would enhance biodegradation, for example, has been born out by subsequent experience. Many of the technologies now in common use such as air sparging, hydrogen peroxide addition, nitrate addition, and bioslurping, are conceptually similar to the first bioremediation systems put into operation. More unexpected, however, were the considerable technical problems associated with delivering oxidants and nutrients to heterogeneous ground water systems. Experience has shown that the success of engineered bioremediation systems depends largely on how effectively directions and rates of ground water flow can be controlled, and thus how efficiently oxidants and nutrients can be delivered to contaminated aquifer sediments.The early expectation that injecting laboratory‐selected or genetically engineered cultures of hydrocarbon‐degrading bacteria into aquifers would be a useful bioremediation technology has not been born out by subsequent experience. Rather, it appears that petroleum hydrocarbon‐degrading bacteria are ubiquitous in ground water systems and that bacterial addition is usually unnecessary. Perhaps the technology that was least anticipated by early investigators was the development of intrinsic bioremediation. Experience has shown that natural attenuation mechanisms ‐ biodegradation, dilution, and sorption ‐ limit the migration of contaminants to some degree in all ground water systems. Intrinsic bioremediation is the deliberate use of natural attenuation processes to treat contaminated ground water to specified concentration levels at predetermined points in the aquifer. In current practice, intrinsic bioremediation of petroleum hydrocarbons requires a systematic assessment to show that ambient natural attenuation mechanisms are efficient enough to meet regulatory requirements and a monitoring program to verify that performance requirements are met in the future.
Field Data and Ground Water Modeling in a Layered Fractured Aquifer
Authors: Gburek W.J. , Folmar GJ. , Urban J.B. 
Published: August 2005

AbstractSurface refraction seismic surveys were conducted within a 7.3 km2 east‐central Pennsylvania watershed to characterize the geometry of its shallow layered and fractured bedrock. These data were augmented with observations from 29 rock cores. Hydraulic conductivity (K) of the bedrock was determined by interval packer testing within the boreholes. Finally, the MODFLOW ground water model was applied to the layered aquifer geometry in a three‐dimensional format to determine watershed‐scale aquifer parameters by model calibration to observed watershed data. Seismic testing showed that the aquifer could be characterized by four distinct layers, each with its own characteristic seismic velocity. Hydraulic conductivity determined by field testing decreased with depth, ranging from greater than 1.0 m day−1 in the shallow, highly fractured layer to approximately 0.01 m day−1 in the regional aquifer. Its distribution with depth reflected the increase in seismic velocities and decrease in extent of fracturing observed in the cores. Aquifer geometry determined from seismic testing and rock cores was used to define model layer geometry, and K values from model calibration compared favorably to those determined by field testing. The ground water 00 model was also used in calibration mode to determine specific yields (S y) of the characteristic fracture layers. These were all low, ranging from 0.005 in the highly fractured layer to 0.0001 in the regional aquifer. When aquifer geometry determined from detailed seismic surveys is used as the basis for watershed‐scale ground water modeling in these shallow layered and fractured systems, hydraulic parameters derived by field testing compare well to those determined by model calibration.