Soil and Water Quality


Book Description

How can the United States meet demands for agricultural production while solving the broader range of environmental problems attributed to farming practices? National policymakers who try to answer this question confront difficult trade-offs. This book offers four specific strategies that can serve as the basis for a national policy to protect soil and water quality while maintaining U.S. agricultural productivity and competitiveness. Timely and comprehensive, the volume has important implications for the Clean Air Act and the 1995 farm bill. Advocating a systems approach, the committee recommends specific farm practices and new approaches to prevention of soil degradation and water pollution for environmental agencies. The volume details methods of evaluating soil management systems and offers a wealth of information on improved management of nitrogen, phosphorus, manure, pesticides, sediments, salt, and trace elements. Landscape analysis of nonpoint source pollution is also detailed. Drawing together research findings, survey results, and case examples, the volume will be of interest to federal, state, and local policymakers; state and local environmental and agricultural officials and other environmental and agricultural specialists; scientists involved in soil and water issues; researchers; and agricultural producers.




Sources, Fate, and Transport of Nitrogen and Phosphorus in the Chesapeake Bay Watershed


Book Description

Spatially Referenced Regression on Watershed Attributes (SPARROW) was used to provide empirical estimates of the sources, fate, and transport of total nitrogen (TN) and total phosphorus (TP) in the Chesapeake Bay watershed, and the mean annual TN and TP flux to the bay and in each of 80,579 nontidal tributary stream reaches. Restoration efforts in recent decades have been insufficient to meet established standards for water quality and ecological conditions in Chesapeake Bay. The bay watershed includes 166,000 square kilometers of mixed land uses, multiple nutrient sources, and variable hydrogeologic, soil, and weather conditions, and bay restoration is complicated by the multitude of nutrient sources and complex interacting factors affecting the occurrence, fate, and transport of nitrogen and phosphorus from source areas to streams and the estuary. Effective and efficient nutrient management at the regional scale in support of Chesapeake Bay restoration requires a comprehensive understanding of the sources, fate, and transport of nitrogen and phosphorus in the watershed, which is only available through regional models. The current models, Chesapeake Bay nutrient SPARROW models, version 4 (CBTN_v4 and CBTP_v4), were constructed at a finer spatial resolution than previous SPARROW models for the Chesapeake Bay watershed (versions 1, 2, and 3), and include an updated timeframe and modified sources and other explantory terms.




Root Zone Water Quality Model


Book Description

This publication comes with computer software and presents a comprehensive simulation model designed to predict the hydrologic response, including potential for surface and groundwater contamination, of alternative crop-management systems. It simulates crop development and the movement of water, nutrients and pesticides over and through the root zone for a representative unit area of an agricultural field over multiple years. The model allows simulation of a wide spectrum of management practices and scenarios with special features such as the rapid transport of surface-applied chemicals through macropores to deeper depths and the preferential transport of chemicals within the soil matrix via mobile-immobile zones. The transfer of surface-applied chemicals (pesticides in particular) to runoff water is also an important component.




Chemical Fate and Transport in the Environment


Book Description

Chemical Fate and Transport in the Environment is a textbook for upper division undergraduate and graduate students studying environmental sciences in engineering, hydrology, chemistry, and other related disciplines. It covers the fundamental principles of mass transport and chemical partitioning, and the transformation of substances in surface water, in groundwater or subsurface environments, and in the atmosphere. Three major areas-surface water, ground water, and air-are covered, with descriptive overviews for each area. Each major section begins by describing environment: its controlling physical, chemical, and biological processes. The book also contains examples of common environmental problems and includes problem sets at the end of each chapter.Text that has been developed from a course taught at MITBroad-based coverage of the environmental sciencesA more rigorous treatment of transport than found in other textsExercise sets at the end of each chapterExamples of current environmental problems fully integrated into the textAmple references for access to the primary literatureNumerous illustrations throughout







Pesticides in the Soil Environment


Book Description

Pesticides in the soil environment - an overview. Pesticide sources to the soil and principles of spray physics. The retention processes: mechanisms. Sorption estimates for modeling. Abiotic transformations in water, sediments, and soil. Biological transformation processes of pesticides. Volatilization and vapor transport processes. Organic chemical transport to Groundwater. Movement of pesticides into surface waters. Modeling pesticide fate in soils. Efficacy of soil-applied pesticides. Impact of pesticides on the environment. Risk/benefit and regulations. Chemical index.




Conceptual Models of Flow and Transport in the Fractured Vadose Zone


Book Description

Fluid flow and solute transport within the vadose zone, the unsaturated zone between the land surface and the water table, can be the cause of expanded plumes arising from localized contaminant sources. An understanding of vadose zone processes is, therefore, an essential prerequisite for cost-effective contaminant remediation efforts. In addition, because such features are potential avenues for rapid transport of chemicals from contamination sources to the water table, the presence of fractures and other channel-like openings in the vadose zone poses a particularly significant problem, Conceptual Models of Flow and Transport in the Fractured Vadose Zone is based on the work of a panel established under the auspices of the U.S. National Committee for Rock Mechanics. It emphasizes the importance of conceptual models and goes on to review the conceptual model development, testing, and refinement processes. The book examines fluid flow and transport mechanisms, noting the difficulty of modeling solute transport, and identifies geochemical and environmental tracer data as important components of the modeling process. Finally, the book recommends several areas for continued research.




Drainage in the 21st Century


Book Description

Presents 86 contributions from the March 1998 symposium exploring the technology of drainage and water table control. Writers from the science, industrial, and research areas provide information on water quality, salinity, modeling, drainage, measurement technique, water table management, and plans for a sustainable South Florida. specific topics include reclamation of saline clay soils in Egypt, environmental impacts of agriculture drainage in the Midwestern U.S., and an artificial neural network for water table management systems. Annotation copyrighted by Book News, Inc., Portland, OR