Download or read book Measurement and Modeling of Solute Diffusion Coefficients in Unsaturated Soils written by Hsin-Yi Chou and published by . This book was released on 2010 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although solute diffusion in soil has been widely examined under the influence of both soil-water content and matric potential, little information is available about the impact of soil-water content/matric potential hysteresis on solute diffusion. Our research shows that the unequal soil-water content at a given matric potential when a soil is subjected to drying or wetting process has substantial impact on solute diffusion. The measured solute diffusion coefficients of drying were greater than those of wetting in certain soil-water content range. When fitted the solute diffusion coefficients of drying and wetting limbs by proposed predictive models, the drying limb is better described by a power function of soil-water content with empirical constants estimated by particle-size distribution and bulk density; while the wetting limb is better described by a conceptual model which assumes the solute diffusive pathway is comprised of the serial arrangement of pore water and film water. This research concluded that the behavior of solute diffusion in unsaturated soils is essentially determined by the liquid phase distribution.
Download or read book Development of a diffusion cell for unsaturated soils written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nos projetos de locais de disposição de resíduos e na avaliação da contaminação do solo e da água subterrânea por substâncias químicas orgânicas e inorgânicas, é essencial que se conheça os mecanismos de transporte de contaminantes por estes meios. São dois os processos básicos no transporte de solutos: advecção e dispersão hidrodinâmica. Advecção é o processo através do qual a água subterrânea carrega consigo os solutos dissolvidos. A quantidade de soluto transportado depende de sua concentração na águasubterrânea, do volume de água fluindo e da velocidade da água subterrânea. O mecanismo de dispersão hidrodinâmica engloba o mecanismo de dispersão mecânica e o transporte pordifusão. A medida que o soluto se movimenta no meio poroso, o processo de dispersão age no sentido de diluir o soluto e reduzir sua concentração. A difusão é o processo através do qual as espécies moleculares e iônicas dissolvidas na água se movem devido a um gradiente de concentração, indo das áreas de maior para menor concentração, mesmo na ausência de fluxo de água subterrânea. O transporte difusivo através de um meio não saturado é mais complicado do que através demeios saturados. Neste caso os parâmetros de transporte podem variar no espaço e no tempo. Portanto, a determinação destes parâmetros no laboratório deve ser feito nas condições mais próximas possíveis das condições in situ. Os processos através dos quais as substâncias se movem através do solo podem ser expressos por modelos matemáticos. Eles se baseiam na integração da equação advectiva-dispersiva utilizando condições de contorno específicas para o sistema de interesse. Entretanto, suaaplicabilidade é limitada devido à falta de parâmetros experimentais confiáveis. Esta tese procura preencher o espaço entre os modelos numéricos e os estudos experimentais. Um novo difusímetro foi desenvolvido para medir o coeficiente de difusão em solos não saturados. O projeto combina o método do reservatório simple, proposto por Rowe et al. (1988), com a técnica de controle osmótico. Foram feitos ensaios com sucção variando entre 0 e 500 kPa. Os solutos utilizados foram cloreto de sódio e cloreto de potássio difundindo através de um amostra relativamente inerte, preparada em laboratório. Os resultados obtidosindicam que a nova técnica proposta funciona bem, sendo entretanto recomendado maiores desenvolvimentos no sistema de controle de sucção, através do uso de instrumentação maisprecisa.
Download or read book Unsaturated Soils Volume 3 written by J.F.T Juca and published by CRC Press. This book was released on 2021-05-30 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unsaturated materials comprise residua, collapsible and expansive naturally occurring soils, compacted soils and, more recently, residues of solid wastes. The engineering problems associated with unsaturated materials range from those related to conventional geotechnical works (e.g. foundations, pavements, slopes and excavations, retaining structures, earthdams, irrigation canals, tunnelling, compacted embankments) to those included in the environmental area (e.g. natural slope instability, erosion and subsidence processes, tailings, residues or solid waste disposal, contaminant transport, remediation of contaminant sites, engineered barriers for environmental protection, re-use of residues). This book, published in three separate volumes, comprises a selection of selected and invited papers presented at the Third International Conference on Unsaturated Soils – UNSAT ‘2002 – that took place in Recife, Brazil, form 10th to 13th March 2002. The book is of interest to consultants, researchers, practitioners, lecturers and students with a background in geotechnical engineering, environmental engineering and engineering geology.
Download or read book Handbook of Soil Sciences Two Volume Set written by Pan Ming Huang and published by CRC Press. This book was released on 2018-10-03 with total page 2249 pages. Available in PDF, EPUB and Kindle. Book excerpt: An evolving, living organic/inorganic covering, soil is in dynamic equilibrium with the atmosphere above, the biosphere within, and the geology below. It acts as an anchor for roots, a purveyor of water and nutrients, a residence for a vast community of microorganisms and animals, a sanitizer of the environment, and a source of raw materials for co
Download or read book The Handbook of Groundwater Engineering Third Edition written by John H. Cushman and published by CRC Press. This book was released on 2016-11-25 with total page 1726 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new edition adds several new chapters and is thoroughly updated to include data on new topics such as hydraulic fracturing, CO2 sequestration, sustainable groundwater management, and more. Providing a complete treatment of the theory and practice of groundwater engineering, this new handbook also presents a current and detailed review of how to model the flow of water and the transport of contaminants both in the unsaturated and saturated zones, covers the protection of groundwater, and the remediation of contaminated groundwater.
Download or read book Methods of Soil Analysis Part 4 written by Jacob H. Dane and published by John Wiley & Sons. This book was released on 2020-05-27 with total page 1744 pages. Available in PDF, EPUB and Kindle. Book excerpt: The best single reference for both the theory and practice of soil physical measurements, Methods, Part 4 adopts a more hierarchical approach to allow readers to easily find their specific topic or measurement of interest. As such it is divided into eight main chapters on soil sampling and statistics, the solid, solution, and gas phases, soil heat, solute transport, multi-fluid flow, and erosion. More than 100 world experts contribute detailed sections.
Download or read book Unsaturated Soil Moisture Drying and Wetting Diffusion Coefficient Measurements in the Laboratory written by Daniel Mabirizi and published by . This book was released on 2009 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soilless Culture Theory and Practice written by Michael Raviv and published by Elsevier. This book was released on 2019-03-30 with total page 713 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soilless Culture: Theory and Practice, Second Edition, is the first authoritative reference book on both the theoretical and practical aspects of growing plants without the use of soil. It is the go-to source for those involved in this practice, focusing on hydroponics and advancements in technologies and methodologies. The book builds on the thorough presentation of both physical and chemical properties of various soilless growing media, also addressing how these properties affect plant performance in basic horticultural operations, such as irrigation and fertilization. In addition, the book describes the latest technical advancements and methodologies, including run-to-waste, re-circulation and closed systems. - Provides a fully revised and updated edition with key insights on all current media types for plant production - Explains the latest information on water and nutrient availability - Includes rootstock/scion relationships in substrates - Contains a chapter focusing specifically on hydroponics
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1991 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Networks on Networks written by Allen G. Hunt and published by Morgan & Claypool Publishers. This book was released on 2016-01-01 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: Order from chaos is simultaneously a mantra of physics and a reality in biology. Physicist Norman Packard suggested that life developed and thrives at the edge of chaos. Questions remain, however, as to how much practical knowledge of biology can be traced to existing physical principles, and how much physics has to change in order to address the complexity of biology. Phil Anderson, a physics Nobel laureate, contributed to popularizing a new notion of the end of “reductionism.” In this view, it is necessary to abandon the quest of reducing complex behavior to known physical results, and to identify emergent behaviors and principles. In the present book, however, we have sought physical rules that can underlie the behavior of biota as well as the geochemistry of soil development. We looked for fundamental principles, such as the dominance of water flow paths with the least cumulative resistance, that could maintain their relevance across a wide range of spatial and temporal scales, together with the appropriate description of solute transport associated with such flow paths. Thus, ultimately, we address both nutrient and water transport limitations of processes from chemical weathering to vascular plant growth. The physical principles guiding our effort are established in different, but related concepts and fields of research, so that in fact our book applies reductionist techniques guided by analogy. The fact that fundamental traits extend across biotic and abiotic processes, i.e., the same fluid flow rate is relevant to both, but that distinctions in topology of the connected paths lead to dramatic differences in growth rates, helps unite the study of these nominally different disciplines of geochemistry and geobiology within the same framework. It has been our goal in writing this book to share the excitement of learning, and one of the most exciting portions to us has been the ability to bring some order to the question of the extent to which soils can facilitate plant growth, and what limitations on plant sizes, metabolism, occurrence, and correlations can be formulated thereby. While we bring order to the soil constraints on growth , we also generate some uncertainties in the scaling relationships of plant growth and metabolism. Although we have made an first attempt to incorporate edaphic constraints into allometric scaling, this is but an initial foray into the forest.
Download or read book The Biogeochemistry of Submerged Soils written by Guy Kirk and published by John Wiley & Sons. This book was released on 2004-06-25 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Submerged soils and the wetlands they support are of huge practical importance: in global element cycles, as centres of biodiversity, in global food production. They are also uniquely interesting scientifically because of their peculiar biogeochemistry and the adaptations of plants and microbes to it. This book describes the physical, chemical and biological processes operating in submerged soils and governing their properties. It describes the transport processes controlling the fluxes of gases and solutes through the soil; the interchange of solutes between solid, liquid and gas phases; reduction and oxidation processes; biological processes in the soil and overlying water; and processes in the roots and rhizospheres of wetland plants. The dynamics of nutrients, toxins, pollutants and trace gases are then discussed in terms of these processes and in relation to wetland productivity and global element cycles. Written by a renowned expert in the field, this work will be invaluable to earth, environmental and agricultural scientists concerned with natural or man-made wetlands, and to advanced undergraduate and graduate studen ts of these topics.
Download or read book Measuring and Modeling of Water and Solute Flow in Macroporous Silt Loam Soils written by Brian J. Lepore and published by . This book was released on 2007 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Determination of Diffusion Coefficient for Unsaturated Soils written by Eeshani Sood and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The structures constructed on unsaturated soils are damaged by the movement of the soil underneath. The movement is basically due to the flow of moisture in and out of the soil. This change in moisture also affects the strength of the soil, thus resulting in failure of slopes of embankments constructed with these soils. Therefore, it is very important to study the diffusion properties of unsaturated soils. Study of the diffusion properties requires the determination of the diffusion coefficient ([alpha]). In this thesis improvements in the drying test, originally proposed by Mitchell(1979), have been discussed. The study also involves defining the evaporation coefficient(h[subscript]e) which has been ill-defined in previous research work. The flow through unsaturated soils is non-linear but due to the complexity involved it has been simplified to a linear problem. The nonlinear behavior has been studied during this research. Therefore, certain refinements have been applied in the determination of the diffusion coefficient. The laboratory procedure followed involves measuring the soil suction along the length of the sample and at different times using thermocouple psychrometers. The evaluation of the evaporation coefficient (h[subscript]e) has been made an integral part of the procedure. The diffusion coefficient is determined using the curve fitting procedure of Aubeny and Lytton, 2003.
Download or read book Percolation Theory for Flow in Porous Media written by Allen Hunt and published by Springer. This book was released on 2014-02-04 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph presents, for the first time, a unified and comprehensive introduction to some of the basic transport properties of porous media, such as electrical and hydraulic conductivity, air permeability and diffusion. The approach is based on critical path analysis and the scaling of transport properties, which are individually described as functions of saturation. At the same time, the book supplies a tutorial on percolation theory for hydrologists, providing them with the tools for solving actual problems. In turn, a separate chapter serves to introduce physicists to some of the language and complications of groundwater hydrology necessary for successful modeling. The end-of-chapter problems often indicate open questions, which young researchers entering the field can readily start working on. This significantly revised and expanded third edition includes in particular two new chapters: one on advanced fractal-based models, and one devoted to the discussion of various open issues such as the role of diffusion vs. advection, preferential flow vs. critical path, universal vs. non-universal exponents for conduction, and last but not least, the overall influence of the experimental apparatus in data collection and theory validation. "The book is suitable for advanced graduate courses, with selected problems and questions appearing at the end of each chapter. [...] I think the book is an important work that will guide soil scientists, hydrologists, and physicists to gain a better qualitative and quantitative understanding of multitransport properties of soils." (Marcel G. Schaap, Soil Science Society of America Journal, May-June, 2006)
Download or read book Physical Nonequilibrium in Soils written by H. Magdi Selim and published by CRC Press. This book was released on 2022-01-27 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Physical Nonequilibrium in Soils provides cutting-edge knowledge on physical nonequilibrium phenomena in soils, offering unique insight into the complexity of our physical world. With 18 chapters comprising the book, topics cover soil properties fluid properties mechanistic models transfer function geostatistics fractal analysis cellular-automation fluids coupling of physical and chemical nonequilibrium models confirming and quantifying physical nonequilibrium in soils analytical solutions field-scale research environmental impacts.
Download or read book Research Reporting Series written by and published by . This book was released on 1973 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Selected Irrigation Return Flow Quality Abstracts 1970 1971 written by Gaylord V. Skogerboe and published by . This book was released on 1973 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
