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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 47 for “"natural attenuation"”.
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Natural Attenuation Software (NAS): Assessing Remedial Strategies and Estimating Timeframes
Natural Attenuation Software (NAS) was developed as a screening tool to estimate remediation timeframes for monitored natural attenuation (MNA) to lower groundwater contaminant concentrations to regulatory limits, and to assist in decision-making on the level of source zone treatment in conjunction …
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Natural attenuation of organophosphates in river systems: Chattahoochee River case study
… study is an attempt to identify the presence of natural removal processes for these three organophosphoric acid triesters within the Chattahoochee River near Atlanta, Georgia, USA. Samples were collected during the month of January at various sites along the Chattahoochee River. They were …
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Natural attenuation of chlorinated solvents at Ashumet Valley, Cape Cod, Massachusetts
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1997.
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Design Methodology for Permeable Reactive Barriers Combined With Monitored Natural Attenuation
… not properly account for all major physical and attenuation processes driving remediation. This study focused on developing a simple methodology to design PRBs that is easy to implement while improving accuracy and being more conservative than the available design methodologies. An empirical …
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Evaluating the natural attenuation of synthetic organic chemicals in a chalk aquifer
… This has sparked an interest in the use of naturally occurring processes to degrade contaminants in the subsurface and has opened up an area of research focusing on „natural attenuation‟. For the successful application of natural attenuation and in order to obtain regulatory approval a …
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Eignung von Mikrokosmen zur Bewertung von Selbstreinigungsprozessen (Natural Attenuation) im Grundwasser eines ehemaligen Kokereigeländes
… des natürlichen Schadstoffabbaus im Grundwasser (Natural Attenuation, NA) müssen die verantwortlichen Prozesse identifiziert, bewertet und quantifiziert werden. Zur Einschätzung des NA-Potenzials an einem ehemaligen Kokereistandort wurden im Rahmen dieser Arbeit Mikrokosmenversuche durchgeführt. …
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Evaluating the sustainability of monitored natural attenuation in groundwater at chlorinated ethene contaminated sites
Monitored natural attenuation (MNA) has been widely used as a remedial strategy, acknowledged by the EPA as the most appropriate technology for cost effective remediation under certain site conditions. Despite the widespread use of MNA, empirical methods are lacking to evaluate the sustainability …
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Chemical Processes That Govern the Natural Attenuation of Microbial Signals: Environments That Simulate Photosynthetic Biofilms
… of reactions collectively referred to as 'natural attenuation.' Mechanisms of natural attenuation include oxidation, substitution, photolysis, etc, largely as function of the local conditions. This implies that natural attenuation can inhibit microbial self-detection mechanisms such as …
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Impacts of Sequential Microbial Electron Accepting Processes on Natural Attenuation of Selected Petroleum Hydrocarbons in the Subsurface Environment
Regulatory acceptance of monitored natural attenuation (MNA) requires demonstration that natural processes, such as sorption and biodegradation, attenuate specific contaminants of concern on a time scale that is comparable to other remediation options while concurrently preventing contaminant …
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Origin of Uranium Mineralization at Coles Hill Virginia (USA) and its Natural Attenuation within an Oxidizing Rock-Soil-Ground Water System
… and contaminants requires information from natural geologic systems. The following study of the Coles Hill uranium deposit and associated weathered zone constrains processes leading to the natural attenuation of uranium within an oxidizing, fluid rich environment typical of the eastern US. …
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The impact of urban groundwater upon surface water quality : Birmingham - River Tame study, UK
… lower than expected and ascribed to dilution and natural attenuation within the aquifer and riverbed. High concentration plumes were detected, but their effect was localised due to substantial dilution within the overlying water column of the river. Estimated contaminant fluxes were not found to …
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Sustainability of Reductive Dechlorination at Chlorinated Solvent Contaminated Sites: Metrics for Assessing Potentially Bioavailable Natural Organic Carbon in Aquifer Sediments
… and economical remedial technologies. Monitored natural attenuation (MNA) has become accepted by federal regulatory agencies as a viable remediation strategy for contaminants under site-specific conditions. At chloroethene contaminated sites where MNA is used as a remediation strategy, …
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Spatial Relationships Between Potential Bioavailable Organic Carbon and Sediment Grain Size at a Chlorinated Solvent-Contaminated Site
… contamination in developed countries. Natural attenuation of chlorinated ethenes is possible through the process of microbial reductive dechlorination. Reductive dechlorination can occur in contaminated aquifers where there are sufficient amounts of organic carbon and reducing redox …
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Sequential Electron Acceptor Model of Intrinsic Bioremediation at a BTEX Contaminated LUST Site in Laurel Bay, South Carolina
… aid engineers in evaluating the feasibility of natural attenuation as a remediation alternative in groundwater systems. In this research, a three-dimensional sequential electron acceptor computer model, SEAM3D, developed by Waddill and Widdowson (1997) was used to simulate contaminant transport …
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Assessment of Microbial Biodegradation of Mixed Soil Contaminants at the Santa Susan Field Laboratory Using TRFLP, qPCR, and Culturing
… determine if biodegradation is contributing to natural attenuation of contaminants in the soil, what organisms are likely causing biodegradation, and what rate(s) can be expected in the future. A literature review was conducted to investigate the chemical properties of theses COIs, their …
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Biogeophysical approaches to monitoring contaminated and restored sites
… One of the main interests is the monitoring of natural attenuation at contaminated sites, as well as planning options to accomplish this. The application of geophysical / electrical methods to monitor / investigate microbial mechanisms in the subsurface are likely to have signification …
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Assessment of Intrinsic Bioremediation at a PCE Contaminated Site
… undertaken to assess the potential of Monitored Natural Attenuation as a remediation strategy at Site 12 at the Naval Amphibious Base (NAB) Little Creek. Site 12 was contaminated with PCE waste disposed by a former dry cleaning facility. In the groundwater analysis, contaminant characteristics …
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Numerical models of phosphate esters in the Chattahoochee River
… to be the most resistant to degradation by natural attenuation processes. Tri (2- butoxyethyl) phosphate showed the most potential for degradation in surface waters. Biodegradation and sorption to settling solids were predicted to be the most effective processes for the removal of tri …
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Computational Tools for Improved Analysis and Assessment of Groundwater Remediation Sites
… Source reduction combined with Monitored Natural Attenuation (MNA) is a remediation strategy whereby the source of contamination is aggressively treated or removed and the residual groundwater plume depletes due to natural processes in the subsurface. The USEPA requires long-term …
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Assessing Various Technologies to Remediate a Hydrocarbon Contaminated Aquifer
… applied to simulate four remedial options: (1) natural attenuation, (2) groundwater extraction, (3) groundwater flushing, and (4) microbial fences. Results of the predictive simulations indicated that the groundwater flushing remedial option provided the greatest reduction of benzene and TEX …
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