Download or read book VADOSE ZONE MODELING OF ORGANIC POLLUTANTS written by S. C. Hern and published by Springer. This book was released on 1986-10 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: An overview of chemical fate and transport modeling in the vadose zone. Chemical processes, parameter estimation, and variability in the vadose zone. Mathematical derivation of chemical transport equations.

Download or read book Evaluation of Unsaturated vadose Zone Models for Superfund Sites written by D. L. Nofziger and published by . This book was released on 1994 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vadose Zone Contamination Measurement and Modeling written by and published by . This book was released on 1993 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigated the effects of the slow sorption mechanism on the transport of volatile organic contaminants in the vadose zone. Recent research has shown that slow sorption may have a significant impact on the transport of volatile organic compounds in the subsurface. Specifically, this document examined the effects of slow sorption on the Vapor Extraction System (VES) and the Purge and Trap Measurement System. It was found that the slow sorption of organic molecules on soil may profoundly influence the efficiency of VES and purge and trap. In addition, this thesis investigated possible alternatives to purge and trap, including the utilization of lasers and optoelectronics. Mathematical simulation and modeling of slow sorption effects during vapor extraction operations was accomplished with the use of the Soil Vapor Extraction (SVE) Computer Model.

Download or read book Uncertainty Analyses of a Vadose Zone Transport Model for Soil Remediation Criteria of Volatile Organic Compounds written by Yue Rong and published by . This book was released on 1995 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Estimation of Volatile Organic Compound Concentrations in the Vadose Zone written by RK. Sextro and published by . This book was released on 1996 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Obtaining defensible and conservative estimates of the nature, extent and concentration of volatile organic compounds (VOCs) in the vadose zone is extremely important when formulating the conceptual model of the site, when performing risk assessments, for estimating contaminant mass, for assessing remedial alternatives, for selecting target areas for cleanup, and/or for making no further action/investigation decisions. Studies have shown that soil gas analytical results provide both a more complete indication of the VOCs present and a higher estimate of their respective concentrations in the vadose zone than the analysis of soil samples alone. For the past several years deep downhole (to 30+ meters) soil gas sampling and analysis has been performed by various consultants during remedial investigations (RIs) and remedial actions (RAs) of the vadose zone at McClellan Air Force Base. A number of these soil gas results have been confirmed by the concurrent collection and analysis (for VOCs) of soil samples (preserved by either refrigeration to 4 degrees centigrade or refrigeration combined with methanol preservation). The use of this VOC sampling and analysis strategy has resulted in the optimization of VOC sampling and analysis procedures, in a better understanding of the relationship between the concentration of VOCs in soil gas and in the soil, and in a more accurate and comprehensive conceptual model for VOC contamination in the vadose zone. The paper will present the methodologies used by the various consultants for sample collection, preservation, and in the analysis of soil gas and soil samples, present the results of a focused QC study on soil gas sampling and analysis, and discuss the correlation between the soil gas and soil matrix analytical results. The current and future strategies for the sampling, analysis, and estimation of VOCs in the vadose zone during RIs and RAs will also be presented.

Download or read book Applications of GIS to the Modeling of Non point Source Pollutants in the Vadose Zone written by Dennis L. Corwin and published by . This book was released on 1996 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Application of Advanced Information Technology in Assessing Environmental Impacts. Opportunities and Limitations of GIS-Based Modeling of Solute Transport at the Regional Scale. Geostatistics: Tools for Advanced Spatial Modeling in GIS. Stochastic Solute Transport Modeling Trends and Their Potential Compatibility with GIS. GIS Applications of Deterministic Solute Transport Models for Regional-Scale Assessment of Non- Point Source Pollutants in the Vadose Zone. The Influence of Transport Variability Structure on Parameter Estimation and Model Discrimination in Field Soils Uncertainty in Regional-Scale Assessments of Non-Point Source Pollutants Sensitivity Analysis for Regional-Scale Solute Transport Modeling GIS and Hydrologic Models of Non-Point Source Pollutants in Subsurface Water. Application of Soil Survey Attribute Data to GIS Pollution Assessment Models. Methods for Estimate Soil Hydraulic Parameters for Regional-Scale Applications of Mechanistic Models. Mapping the Areal Distribution of Soil Parameters with Geophysical Techniques. An Integrated Approach for Modeling Water Flow and Solute Transport in the Vadose Zone. Unsatchemgeo: Modeling Water Flow and Multicomponent Solute Transport in a GIS Context. Baseflow Mapping of the South-Central and Southeastern United States Using GIS. Application of GIS to the Modeling of Pesticide Leaching on a Regional Scale in the Netherlands. NLEAP/GIS Approach for Identifying and Mitigating Regional NO3-N Leaching. GIS Applications to the Basin-Scale Assessment of Soil Salinity and Salt Loading to Groundwater.

Download or read book Inorganic Contaminants in the Vadose Zone written by Bnayahu Bar-Yosef and published by Springer. This book was released on 1989-11-16 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selected Papers from an International Workshop, Israel, June 1987

Download or read book Vadose Zone Contamination Measurement and Modeling written by Thomas A. Reeder (MAJ, USMC.) and published by . This book was released on 1993 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mass Transport of Volatile Organic Compounds Between the Saturated and Vadose Zones written by Monte S. Harner and published by . This book was released on 1996-12-01 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volatile organic compounds (VOCs) dissolved in the saturated zone are transported into the vadose zone primarily by gaseous phase diffusion. If the saturated zone is remediated, VOCs present in the vadose zone may become a secondary source of contamination for the groundwater The amount of VOCs that remain in the vadose zone is dependent on site hydrology, soil properties, and the chemical properties of the contaminants. The purpose of this study was to determine what conditions caused VOC concentrations in the vadose zone to significantly recontaminate the saturated zone. A one-dimensional numerical model was developed to investigate the transport of a VOC, trichioroethylene, between the saturated and vadose zones under a variety of conditions. The model featured steady-state unsaturated water flow and transient contaminant transport Transport mechanisms included aqueous phase advection-dispersion and gaseous phase diffusion. Partitioning between the water, gas, and soil compartments were modeled as equilibrium processes. Sensitivity analyses were performed on several variables including soil type (homogeneous and heterogeneous profiles), water infiltration rate and vadose zone depth. Results indicated that recontamination was most significant rate, and vadose zone depth. Results indicated that recontamination was most significant in the presence of heterogeneous soils, low infiltration rates and deep vadose zones.

Download or read book Environmental Modeling written by Paolo Zannetti and published by Computational Mechanics. This book was released on 1993 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Vadose Zone Characterization Monitoring written by L. Gray Wilson and published by Routledge. This book was released on 2018-05-02 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is written in a simple, straightforward manner without complicated mathematical derivatives. Compiled by experienced practitioners, this guide covers topics such as basic principles of vadose zone hydrology and prevalent monitoring techniques. Case studies present actual field experiences for the benefit of the reader. The Handbook provides practitioners with the information they need to fully understand the principles, advantages, and limitations of the monitoring techniques that are available. The Handbook of Vadose Zone Characterization & Monitoring expands and consolidates the useful and succint information contained in various ASTM documents, EPA manuals, and other similar texts on the subject, making it an invaluable aid to new practioners and a useful reference for seasoned veterans in the field.

Download or read book Assessing the Mobility of Chemicals in the Vadose Zone written by Donn Louis Marrin and published by . This book was released on 1991 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modelling of Pollutants in Complex Environmental Systems written by Grady Hanrahan and published by ILM Publications. This book was released on 2009 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: This title showcases modern environmental modelling methods, the basic theory behind them and their incorporation into complex environmental investigations.

Download or read book Natural Attenuation Assessment of Multiple VOCs in a Deep Vadose Zone written by and published by . This book was released on 2000 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fate of six volatile organic compounds (VOC) in a 150-meter deep vadose zone was examined in support of a RCRA Corrective Measures Study of the Chemical Waste Landfill at Sandia National Laboratories, Albuquerque, New Mexico. The study focused on the modeling of potential future transport of the VOCs to exposure media upon the completion of two separate voluntary corrective measures--soil vapor extraction and landfill excavation--designed to significantly reduce contaminant levels in subsurface soils. modeling was performed with R-UNSAT, a finite-difference simulator that was developed by the U.S. Geological Survey. R-UNSAT facilitated a relatively unique and comprehensive assessment of vapor transport because it (1) simulated the simultaneous movement of all six VOCs, taking into account each constituent's diffusion coefficient as affected by its mole fraction within a mixture of chemicals, and (2) permitted simultaneous assessment of risk to human health via volatilization (air) and drinking water (groundwater) pathways. Modeling results suggested that monitored natural attenuation would represent a viable remedial alternative at the landfill after both voluntary corrective measures were completed.

Download or read book Integrated Environmental Modeling written by Anu Ramaswami and published by John Wiley & Sons. This book was released on 2005-04-15 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unified presentation of environmental model development, implementation, and testing Integrated Environmental Modeling teaches model development, model implementation, and model testing skills in a unified manner, crosscutting the three "media" comprising environmental systems--air, water, and soil--by focusing on parallels and similarities between them, and introducing a new generation of multimedia models. No other single volume offers comprehensive coverage of chemical transport and fate in all three environmental media, including the resulting impacts on the biosphere and human health, with a focus on the fundamental processes underlying environmental modeling. Integrated Environmental Modeling provides broad-based training in the development of pollutant transport and fate models in air, water, and soil, with a focus on five essential competencies: * Understanding the fundamental process principles that govern contaminant transport and transformations in multimedia environments, emphasizing the parallels and links between different media * Learning model development skills, starting from the simplest conceptual models and building more complex and realistic models that couple component process modules at the appropriate spatial and temporal scales of resolution * Using statistical methods and data sources to estimate input parameters and characterize model sensitivity and uncertainty * Gaining hands-on experience with computer-aided implementation and evaluation of fate and transport models using realistic case study examples * Applying fate and transport models to evaluate pollutant interactions with the biosphere, particularly in human exposure modeling and health risk assessment Complete with case studies, Integrated Environmental Modeling is a valuable, single-source tool for senior and graduate students in environmental science and engineering courses on pollutant transport, remediation, and risk assessment, and an essential reference text for professionals in industry, consulting, and government agencies responsible for environmental assessment and risk analysis.

Download or read book Integrated Field Laboratory and Modeling Studies to Determine the Effects of Linked Microbial and Physical Spatial Heterogeneity on Engineered Vadose Zone Bioremediation written by and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: While numerous techniques exist for remediation of contaminant plumes in groundwater or near the soil surface, remediation methods in the deep vadose zone are less established due to complex transport dynamics and sparse microbial populations. Yet pollution in the vadose zone poses a serious threat to the groundwater resources lying deeper in the sediment. While the contaminant may be slowly degraded by native microbial communities; microbial degradation rates rarely keep pace with the spread of the pollutant. Hydrologic and microbiological properties of the zone, and their interactions, are fundamentally different from the saturated zone: the vadose zone has an additional phase (air), higher levels of oxygen, and contaminant transport and water movement is predominantly perpendicular to geologic strata and occurs in water films. In addition, microbial populations in the vadose zone are sparse and spatially discontinuous, especially in arid climates. At the Department of Energy's Hanford site in Richland, WA, numerous recalcitrant organic compounds were disposed of in the vadose zone, and now are continual sources of groundwater pollution. Among the most problematic of these is a plume of carbon tetrachloride (CT), a common solvent, the majority of which still resides in the vadose zone despite the presence of microbes that can degrade it and its byproduct chloroform. Gaseous nutrients can in principle be used to stimulate the native degrading population and has shown some promise in isolated field cases. However, there is a lack of knowledge on how physical and hydrologic features of the vadose zone control the spatial distribution of microbes, and the extent that microbes can colonize the vadose zone in response to nutrient delivery during bioremediation. The overall objective of the project was to increase knowledge of the feasibility of engineered bioremediation in the deep vadose zone, particularly at arid western sites where microbial populations and activities are low. Specific objectives were to: (1) Conduct laboratory studies of how physical and hydrologic features of the vadose zone control the spatial distribution of microbial growth and the ability of microorganisms to colonize microbially sparse or ''empty'' regions of the vadose zone. (2) Characterize microbiological properties of a carbon tetrachloride-contaminated deep vadose zone site at the DOE Hanford Site. (3) Evaluate the potential for gas phase feeding of carbon, nitrogen, and phosphorus to deep vadose zone microbial communities. (4) Use field and laboratory data generated from the project to parameterize an unsaturated zone transport model with microbial growth, colonization, and biotransformation kinetics and conduct reactive transport simulations. Pacific Northwest National Lab (PNNL) and Oregon State University (OSU) jointly addressed objectives 1, 3, and 4. PNNL addressed objective 2. For objective 4, laboratory data was simulated during the project; field data was not used in modeling and simulation due to the late initiation of the field study and the small number (n=24) of samples studied.

Download or read book Environmental Modeling and Management written by and published by . This book was released on 2002 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: