Download or read book Numerical Simulation of a Natural Gradient Tracer Experiment for the Natural Attenuation Study Flow and Physical Transport written by Thomas B. Stauffer and published by . This book was released on 2001 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are presented for numerical simulations of ground water flow and physical transport associated with a natural gradient tracer experiment conducted within a heterogeneous alluvial aquifer of the Natural Attenuation Study (NATS) site near Columbus, Mississippi. A principal goal of NATS is to evaluate biogeochemical models that predict the rate and extent of natural biodegradation under field conditions. This paper describes the initial phase in the model evaluation process, i.e., calibration of flow and physical transport models that simulate conservative bromide tracer plume evolution during NATS. An initial large-scale flow model (LSM) is developed encompassing the experimental site and surrounding region. This model is subsequently scaled down in telescopic fashion to an intermediate-scale ground water flow model (ISM) covering the tracer-monitoring network, followed by a small-scale transport model (SSM) focused on the small region of hydrocarbon plume migration observed during NATS. The LSM uses inferred depositional features of the site in conjunction with hydraulic conductivity (K) data from aquifer tests and borehole flowmeter tests to establish large-scale K and flow field trends in and around the experimental site. The subsequent ISM incorporates specified flux boundary conditions and large-scale K trends obtained from the calibrated LSM, while preserving small-scale K structure based on some 4000 flowmeter data for solute transport modeling. The configuration of the ISM-predicted potentiometric surface approximates that of the observed surface within a root mean squared error of 0.15 m. The SSM is based on the dual-domain mass-transfer approach. Despite the well-recognized difficulties in modeling solute transport in extremely heterogeneous media as found at the NATS site, the dual-domain model adequately reproduced the observed bromide concentration distributions.
Download or read book An Introduction to Solute Transport in Heterogeneous Geologic Media written by Tian-Chyi Jim Yeh and published by Cambridge University Press. This book was released on 2023-02-09 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past several decades, analyses of solute migration in aquifers have widely adopted the classical advection-dispersion equation. However, misunderstandings over advection-dispersion concepts, their relationship with the scales of heterogeneity, our observation and interest, and their ensemble mean nature have created furious debates about the concepts' validity. This book provides a unified and comprehensive overview and lucid explanations of the stochastic nature of solute transport processes at different scales. It also presents tools for analyzing solute transport and its uncertainty to meet our needs at different scales. Easy-to-understand physical explanations without complex mathematics make this book an invaluable resource for students, researchers, and professionals performing groundwater quality evaluations, management, and remediation.
Download or read book Effective Groundwater Model Calibration written by Mary C. Hill and published by John Wiley & Sons. This book was released on 2006-08-25 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods and guidelines for developing and using mathematical models Turn to Effective Groundwater Model Calibration for a set of methods and guidelines that can help produce more accurate and transparent mathematical models. The models can represent groundwater flow and transport and other natural and engineered systems. Use this book and its extensive exercises to learn methods to fully exploit the data on hand, maximize the model's potential, and troubleshoot any problems that arise. Use the methods to perform: Sensitivity analysis to evaluate the information content of data Data assessment to identify (a) existing measurements that dominate model development and predictions and (b) potential measurements likely to improve the reliability of predictions Calibration to develop models that are consistent with the data in an optimal manner Uncertainty evaluation to quantify and communicate errors in simulated results that are often used to make important societal decisions Most of the methods are based on linear and nonlinear regression theory. Fourteen guidelines show the reader how to use the methods advantageously in practical situations. Exercises focus on a groundwater flow system and management problem, enabling readers to apply all the methods presented in the text. The exercises can be completed using the material provided in the book, or as hands-on computer exercises using instructions and files available on the text's accompanying Web site. Throughout the book, the authors stress the need for valid statistical concepts and easily understood presentation methods required to achieve well-tested, transparent models. Most of the examples and all of the exercises focus on simulating groundwater systems; other examples come from surface-water hydrology and geophysics. The methods and guidelines in the text are broadly applicable and can be used by students, researchers, and engineers to simulate many kinds systems.
Download or read book Groundwater written by M. Thangarajan and published by Springer Science & Business Media. This book was released on 2007-06-10 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides comprehensive coverage on the assessment and management of groundwater. It contains the work of international experts in the field of groundwater resource evaluation, characterization, augmentation, restoration, modeling and management.
Download or read book In Situ Remediation Engineering written by Suthan S. Suthersan and published by CRC Press. This book was released on 2004-12-28 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Situ Remediation Engineering provides a comprehensive guide to the design and implementation of reactive zone methods for treatment of all major classes of groundwater contamination. It teaches the fundamentals that underlie development of cost-effective reactive zone strategies, guides the selection of cost-effective remedial strategies and provides environmental engineers and scientists with tools to achieve optimal deployment of source area, reactive barrier, and site-wide treatments. It offers extensive coverage of remedial system operation, discussing reagent injection strategies, interpretation of process monitoring results for biological and chemical reactive zone systems, and impacts of treatment processes on aquifer hydraulic characteristics.
Download or read book Index Medicus written by and published by . This book was released on 2002 with total page 1612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. for 1963- include as pt. 2 of the Jan. issue: Medical subject headings.
Download or read book On Single Well Forced Gradient Tracer Tests written by Gareth L. Barns and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Single well forced gradient tracer tests are a potential cost-effective approach to estimate in situ aquifer contaminant fate and transport parameters for use in natural attenuation assessments and remediation schemes. To date dipole flow tracer tests have been used to measure the conservative and hydraulic parameters of an aquifer, while push-pull tests are well characterised for use with biodegrading tracers. The effect of typical aquifer physical heterogeneity on the ability of single well tests to successfully estimate parameters has not yet been characterised. Also, the ability of single well tests to accurately and quickly measure aquifer parameters using tracer mixtures should be analysed. To investigate the effect of physical heterogeneity on single well tests scaled down ultraviolet imaging experiments were performed in a low profile box. Potential tracers for use in mixtures were investigated through column and batch experiments: Inorganic anions and fluorescein, inorganic cations, acetate and trichlorofluoroethene were considered to measure conservative transport parameters, cation exchange capacity, biodegradation potential and hydrophobic sorption respectively. Numerical modelling was used to simulate reactive tracer signals in single well forced gradient tests. Results suggest that dipole flow tracer tests are appropriate for measuring conservative transport parameters and the sorption of lowly retarded tracers, but are not highly suitable for biodegrading tracers. Tests could be performed with non-recirculating flow, allowing simpler modelling, if equal injection and extraction flow rates could be ensured. Push-pull tests are suitable for biodegrading tracers and moderate to highly retarded tracers. This limits the potential to use reactive tracer mixtures in these tests. Dipole flow tracer test breakthrough curves are highly susceptible to heterogeneity, and could be used to identify discrete permeability variations in aquifers. The effect of heterogeneity is not significant on push-pull test breakthrough curves, but seriously affects tracer plume migration. Inorganic anions provided the most reliable conservative tracer. Trichlorofluoroethene was found to be a suitable tracer to measure hydrophobic sorption. The biodegradation surrogate chosen for a field test should biodegrade similarly to the contaminant under study.
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1990 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural Attenuation for Groundwater Remediation written by Commission on Geosciences, Environment, and Resources and published by National Academies Press. This book was released on 2000-08-31 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past decade, officials responsible for clean-up of contaminated groundwater have increasingly turned to natural attenuation-essentially allowing naturally occurring processes to reduce the toxic potential of contaminants-versus engineered solutions. This saves both money and headaches. To the people in surrounding communities, though, it can appear that clean-up officials are simply walking away from contaminated sites. When is natural attenuation the appropriate approach to a clean-up? This book presents the consensus of a diverse committee, informed by the views of researchers, regulators, and community activists. The committee reviews the likely effectiveness of natural attenuation with different classes of contaminants-and describes how to evaluate the "footprints" of natural attenuation at a site to determine whether natural processes will provide adequate clean-up. Included are recommendations for regulatory change. The committee emphasizes the importance of the public's belief and attitudes toward remediation and provides guidance on involving community stakeholders throughout the clean-up process. The book explores how contamination occurs, explaining concepts and terms, and includes case studies from the Hanford nuclear site, military bases, as well as other sites. It provides historical background and important data on clean-up processes and goes on to offer critical reviews of 14 published protocols for evaluating natural attenuation.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2003 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interpretation of Field scale Tracer Experiments Conducted Under Conditions of Natural Gradient in a Discrete Horizontal Fracture written by P. A. Lapcevic and published by . This book was released on 1996 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monitored Natural Attenuation of Inorganic Contaminants in Ground Water written by and published by . This book was released on 2007 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: V.3 ... consists of individual chapters that describe 1) the conceptual background for radionuclides, including tritium, radon, strontium, technetium, uranium, iodine, radium, thorium, cesium, plutonium-americium and 2) data requirements to be met during site characterization.
Download or read book Tracers in Hydrology written by Christian Leibundgut and published by John Wiley & Sons. This book was released on 2011-08-24 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tracers in Hydrology and Water Research is a comprehensive overview of the application of natural and artificial tracers in hydrology and environmental research. Taking a unique approach by providing the reader with a systematic and state of the art description of natural and artificial tracers, the book also covers key analytical techniques and applications, and modern tracer methods in the context of systematic hydrology. Tracers have become a primary tool for process investigation, qualitative and quantitative system analysis and integrated resource management. This book will outline the fundamentals of the subject, and examine the latest research findings, clearly showing the entire process of tracer application through the inclusion of numerous integrated case studies. As many techniques derive from different scientific disciplines (chemistry, biology, physics), the effort of compilation and integration into modern hydrology and environmental science research and application requires substantial continuity and experience, which certifies this group of authors. This book will be an invaluable reference not only for students and researchers within the field of Hydrology and Hydrogeology but also for engineers and other tracer techniques applying users.
Download or read book Natural Attenuation of Fuels and Chlorinated Solvents in the Subsurface written by Todd H. Wiedemeier and published by John Wiley & Sons. This book was released on 1999-03-08 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first comprehensive guide to one of today's most innovative approaches to environmental contamination Natural attenuation is gaining increasing attention as a nonintrusive, cost-effective alternative to standard remediation techniques for environmental contamination. This landmark work presents the first in-depth examination of the theory, mechanisms, and application of natural attenuation. Written by four internationally recognized leaders in this approach, the book describes both biotic and abiotic natural attenuation processes, focusing on two of the environmental contaminants most frequently encountered in groundwater--fuels and chlorinated solvents. The authors draw on a wealth of combined experience to detail successful techniques for simulating natural attenuation processes and predicting their effectiveness in the field. They also show how natural attenuation works in the real world, using numerous examples and case studies from a wide range of leading-edge projects nationwide involving fuel hydrocarbons and chlorinated solvents. Finally, they discuss the evaluation and assessment of natural attenuation and explore the design of long-term monitoring programs. An indispensable reference for anyone working in environmental remediation, Natural Attenuation of Fuels and Chlorinated Solvents in the Subsurface is essential reading for scientists and engineers in a range of industries, as well as state and federal environmental regulators, and professors and graduate students in environmental or chemical engineering.
Download or read book Tracer Hydrology 97 written by A. Kranjc and published by CRC Press. This book was released on 2020-08-26 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection of papers is the proceedings of the 7th International Synosium on Water Tracing in Portoroz/Slovenia from 26-31 May 1997. They address a number of topics in hydrology tracing techniques including: protection of natural resources against pollution; the use of natural and artificial tracers to help to assess contaminant transport in surface waters; and aquifer parameters and modelling.
Download or read book NBS Special Publication written by and published by . This book was released on 1978 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Contaminants in the Subsurface written by National Research Council and published by National Academies Press. This book was released on 2005-04-23 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: At hundreds of thousands of commercial, industrial, and military sites across the country, subsurface materials including groundwater are contaminated with chemical waste. The last decade has seen growing interest in using aggressive source remediation technologies to remove contaminants from the subsurface, but there is limited understanding of (1) the effectiveness of these technologies and (2) the overall effect of mass removal on groundwater quality. This report reviews the suite of technologies available for source remediation and their ability to reach a variety of cleanup goals, from meeting regulatory standards for groundwater to reducing costs. The report proposes elements of a protocol for accomplishing source remediation that should enable project managers to decide whether and how to pursue source remediation at their sites.
