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  • 1
    Electronic Resource
    Electronic Resource
    A Method to Assess Analytical Uncertainties Over Large Concentration Ranges With Reference to Volatile Organics in Water (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 16 (1996), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The uncertainty associated with a volatile organic concentration measurement is a function of variability and bias introduced at the various levels of sample handling: collection, storage, and analysis. During the past decade, sampling materials and the development and/or improvement of sampling protocols have been the subject of considerable research activity. As a result, in cases of samples properly handled, the analytical variability can be the dominant source of uncertainty in a given concentration value. Here analytical variability refers to any error that might arise during analysis, including the detector response error and any sample handling errors common to both standards and samples. This can be a particular concern for field analyses by gas chromatography (GC), Well-established statistical methods are available to estimate analytical uncertainty from linear calibration curves, but these methods are poorly suited for the analysis of volatile organics because organic samples frequently require instrument calibration (usually GC) over several orders of magnitude in concentration. If a single linear calibration curve is used to determine sample concentrations and uncertainties, then unrealistically large uncertainties may be assigned to low concentration samples. However, the methods can be adopted for extended concentration range calibration curves by breaking the overall calibration line down into smaller sub-calibration lines that span smaller ranges. These can then be examined and used selectively to determine concentrations with more appropriate uncertainties attached. The method of multiple callbration line analysis described here is suitable for programming with any high level computer language. It can be used to calculate meaningful analytical uncertainty values for any substance analyzed over a wide range in concentrations (i.e., an order of magnitude or more).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1996.tb00148.x
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  • 2
    Electronic Resource
    Electronic Resource
    Field Demonstration of Permeable Wall Flushing for Biostimulation of a Shallow Sandy Aquifer (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 19 (1999), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A pilot-scale nutrient injection will (NIW) (4 m by 4 m by 1 m) was installed in the Borden Aquifer lo serve as a pulsed injection source of a potassium acetate solution for the stimulation of anaerobic microbial activity. The success of the flushing procedure was evaluated by monitoring the breakthrough of the acetate solution at several multilevel piezometers installed in the wall. Although some variation in the ground water velocity was observed with depth, the wall was flushed with reasonable uniformity after about six hours of injection and withdrawal, representing about one pore volume, Calculations bused on head level data collected during the flush, and on the solute breakthrough curves, indicated that about 90% of the flow induced by the pumping and injecting was confined to the permeable wall. These results show that a permeable wall injection system is a viable method of introducing solutes uniformly to a cross section of aquifer, with minimal perturbation of the natural flow system. In addition lo its importance for the biostimulation system tested in this project the flushing of permeable walls may have applications in other semi-passive remedial systems, such as the rejuvenation of reactive barriers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1999.tb00189.x
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  • 3
    Electronic Resource
    Electronic Resource
    Optimum Hydraulic Conductivity to Limit Contaminant Flux Through Cutoff Walls (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 34 (1996), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Cutoff walls are becoming increasingly attractive options for the control of solute migration from long-term sources of contamination. The main advantage of low permeability enclosures is that they restrict advective transport of solutes away from the source. However, with high concentration source zones surrounded by cutoff walls, there exists the potential for notable mass fluxes outward due to diffusive transport. This paper shows, through the use of the steady-state flux equations, that there is an optimal range of hydraulic conductivities for barrier materials which permit the outward diffusive flux to be counter balanced by an inward advective and dispersive flux. This concept of designing optimum contaminant containment using an inward advective flux to counter the outward diffusive flux is valid for sealable joint sheet pile walls, bentonite-slurry walls and clay liners, but not synthetic membrane materials with extremely low hydraulic conductivities. The effective diffusion coefficient for the common chlorinated organic solvents such as TCE in water-saturated clayey materials is approximately 1 × 10−6 cm2/sec, resulting in an optimum hydraulic conductivity ranging from 1 × 10−6 to 1 × 10−8 cm/sec. This range in hydraulic conductivity is within the range of common barrier materials but not the lowest achievable. The steady-state concentration profile in a slurry cutoff wall can result in a substantial amount of contaminant mass stored within the wall which will need to be considered over the long term or dealt with during site remediation. Large inward advective fluxes reduce the total chemical mass stored within the low permeability barrier material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1996.tb02060.x
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  • 4
    Electronic Resource
    Electronic Resource
    Field Evidence for the Effect of Acetate on Leachate Alkalinity (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 28 (1990), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Alkalinity measurements are routinely conducted as part of standard water–quality determinations. Often, very little interpretation of the values is attempted, and the entire alkalinity is attributed to carbonate or bicarbonate. When landfill leachates are involved, this assumption could be misleading in terms of plume mapping, determining the incrustation potential of the water, or assessing the likelihood of methane generation because substances other than carbonate, for example acetate, can contribute significantly to the sample's alkalinity.A set of landfill leachate samples was collected and analyzed for alkalinity and volatile fatty acids. Acetate was the only organic acid identified. A very strong correlation was observed between acetate and alkalinity. Actual titration curves (volume of acid vs. pH) were compared with curves calculated assuming that acetate and bicarbonate were the two major species contributing the total alkalinity. Excellent agreement was observed between the experimental and theoretical data. Distinct differences in the shapes of the curves for carbonate–dominated and acetate-dominated alkalinities make it possible to distinguish these two classes of water solely on the basis of alkalinity measurements. Water containing acetate titrates with an equivalence point which is less distinct than water containing only carbonate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1990.tb01721.x
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  • 5
    Electronic Resource
    Electronic Resource
    AN IMPROVED METHOD FOR SLUG TESTS IN SMALL-DIAMETER PIEZOMETERS (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 23 (1985), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: . The use of a small packer in slug tests can improve the quality of time versus head level measurements, particularly during the important early stages of the test. The packer is placed in the piezometer below the static water level and inflated. Water is then added to the piezometer until it is full to the top of the casing. The packer is deflated and the times for the water level to reach selected depths are measured with an electric sonde.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1985.tb01961.x
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  • 6
    Electronic Resource
    Electronic Resource
    A Simple and Powerful Method of Parameter Estimation Using Simplex Optimization (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 32 (1994), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The need for objective parameter estimates is common in hydrogeology. The simplex optimization algorithm provides a fast, simple, and versatile method for making such estimates when used to minimize the residuals sum of squares between calculated and observed data points. Examples of the method applied to Pick's Second Law, the advection dispersion equation, and the integrated Monod kinetics equation illustrate its utility. Compiled programs have been developed, and are available on request, for the estimation of diffusion coefficients, contaminant transport parameters (average linear ground-water velocities, dispersivities, porosities), and biodegradation kinetic constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1994.tb00647.x
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  • 7
    Electronic Resource
    Electronic Resource
    A Semipassive Nutrient Injection Scheme for Enhanced In Situ Bioremediation (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 32 (1994), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A permeable wall injection system is capable of introducing dissolved substances into an aquifer in a manner which minimizes the displacement of naturally present ground water, and maximizes the potential for dispersive mixing. The system operates predominantly in a passive mode, and should require relatively little power and small amounts of chemicals. The injection wall is a permeable cutoff wall installed across the path of a contaminant plume. The ground water can be amended with the desired nutrient solution using pumping and injecting wells within the wall. The high permeability of the wall ensures that the injection-withdrawal operation causes flow which is primarily confined to the wall itself. Thus, only a minimal disruption of the ambient flow need result from a nutrient injection. After the nutrients have been introduced to the wall, the pulse is permitted to drift into the aquifer under natural gradient conditions, spreading longitudinally as it goes. Theoretical calculations and preliminary results of a field trial indicate that if this pulsing cycle is repeated at intervals of weeks to months (site-specific), a stable microbial population can be supported at some distance downgradient from the wall.The advantages of this system include the predominantly passive nature of its operation, the effective use of longitudinal dispersion to maximize the mixing of added substances with contaminated ground water, and the flexibility of the system with regard to the types of biodegradation reactions which it can promote.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1994.tb00654.x
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  • 8
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    Transport and Kinetic Studies To Characterize Reactive and Nonreactive Sites on Granular Iron (2010)
    American Chemical Society
    Details
    Publication Date: 2010-07-15
    Print ISSN: 0013-936X
    Electronic ISSN: 1520-5851
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Published by American Chemical Society
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  • 9
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    Effect of Mixed Anions (HCO3−−SO42−−ClO4−) on Granular Iron (Fe0) Reactivity (2009)
    American Chemical Society
    Details
    Publication Date: 2009-08-01
    Print ISSN: 0013-936X
    Electronic ISSN: 1520-5851
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Published by American Chemical Society
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  • 10
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    Major Anion Effects on the Kinetics and Reactivity of Granular Iron in Glass-Encased Magnet Batch Reactor Experiments (2005)
    American Chemical Society
    Details
    Publication Date: 2005-03-01
    Print ISSN: 0013-936X
    Electronic ISSN: 1520-5851
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Published by American Chemical Society
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