Advancement in the science of soil as a medium for plant growth, as a repository for waste remediation, as the living filter and purifyer of waste supplies, and as the physical material upon which we live and build requires a foundational understanding of the biogeochemical system. Kinetics and equilibria of chemical reactions at the plant-soil-water interface govern nutrient availability and fate and transport of chemicals in soil systems. Ultimately, this determines the yield and quality of crops and the quality of land resources including soil and water. Soils are exceedingly complex systems as the authors of this book elegantly illustrate. Knowledge of these complex systems has advanced remarkably because of the ablity to mathematically model chemical reactions and their equilibrium states. Models, while not an end in themselves, can be tested experimentally and new experimental approaches may be suggested by the observations of the behavior of the model. This book successfully contributes to basic concept of chemical equilibria and reactions in soil systems. It further illustrates several specific models that have been developed for use on personal computers. The authors and editors are to be commended for a text that will be well received among the scientific community of biogeoscientists and agronomists. On behalf of the Soil Science Society of America and the American Society for Agronomy, we congratulate the symposium organizers, editors and authors.
LARRY P. WILDING, president
Soil Science Society of America
CALVIN O. QUALSET, president
American Society of Agronomy
The application of chemical equilibrium principles to soils was not intensively studied in years past because soils are complex and variable systems that are also highly dynamic. Even if equilibrium could be assumed for some or all of the chemical components, a quantitative, thermodynamic description of the system is a mathematically difficult and arduous task because of the large number of possible chemical reactions. The development of chemical equilibrium and reaction models and their more recent availability for personal computers has eliminated the drudgery of manually solving dozens of simultaneous thermodynamic equations and has opened new research opportunities for soil chemists. The leaders of the Soil Chemistry Division (S-2) of the Soil Science Society of America recognized that the interest in equilibrium modeling was growing rapidly and that members would benefit by a series of technical, in-depth papers on the subject.
A symposium entitled “Chemical Equilibrium and Reaction Models” was presented at the 1990 annual meeting of the American Society of Agronomy and the Soil Science Society of America held in San Antonio, Texas. The purpose of the forum was to present a wide range of models and to discuss their development and applications. Over a period of two days, large audiences attended thirteen 25-minute presentations and eleven software demonstrations.
Chemical Equilibrium and Reaction Models is a written compilation of the presentations from the symposium. There are nineteen chapters covering development of programs, adsorption models, coupling chemical equilibrium with transport, research applications, use of models in graduate instruction, and detailed descriptions of specific programs. The intended audience for the papers are those using or intending to use chemical models. The papers tend to be technical in content but are readable by a broad cross-section of scientists. They may also be suitable for use in classroom instruction of chemical equilibrium models.
We are very grateful to the authors for their diligence and tremendous efforts. The authors come from many disciplines including chemistry, geochemistry, engineering, and soil science. Their papers are representative of the most up to date knowledge on the subject and should provide an excellent foundation for novices to the field as well as those with vast experience. We would like to express sincere gratitude to the reviewers who unselfishly donated their time and expertise. Finally, we wish to acknowledge the ASA Headquarters staff for their invaluable work in the publication process.
RICHARD H. LOEPPERT, coeditor
Soil and Crop Sciences Texas A&M University College Station, Texas
A. PAUL SCHWAB, coeditor
Department of Agronomy Kansas State University Manhattan, Kansas
SABINE GOLDBERG, coeditor
USDA-ARS, U S. Salinity Laboratory Riverside, California
H.A. Ajwa, Graduate Research Assistant, Department of Agronomy, Iowa State University, Ames, IA 50011
Jerry D. Allison, President, Allison Geoscience Consultants, Inc. Flowery Branch, GA 30542
David S. Brown, Acting Chief, Assessment Branch, USEPA, Athens Environmental Research Laboratory, Athens, GA 30605-2720
Richard G. Burau, Professor Emeritus of Soil Science and Environmental Toxicology, Department of Land, Air and Water Resources, University of California, Davis, CA 95616
R.L. Chaney, Research Agronomist, USDA-ARS, Environmental Chemistry Laboratory, Beltsville, MD 20705
Jacques Coves, Postdoctoral Researcher, Department of Soil and Environmental Sciences, University of California, Riverside, CA 92521; present address is 35, rue des Lois, 31000 Toulouse, France
Charles T. Driscoll, Distinguished Professor of Civil & Environmental Engineering, Department of Civil & Environmental Engineering, Syracuse University, Syracuse, NY 13244-1190
Andrew R. Felmy, Staff Scientist, Thermodynamic and Molecular Geochemistry Group, Battelle Pacific Northwest Laboratories, Richland, WA 99352
Sabine Goldberg, Soil Scientist, USDA-ARS, U.S. Salinity Laboratory, Riverside, CA 92501
J.L. Hutson, Senior Research Associate, Department of Soil, Crop and Atmospheric Sciences, Cornell University, Ithaca, NY 14853
J. J. Jurinak, Professor of Soil Chemistry, Plants, Soils & Biometeorology Department, Utah State University, Logan, UT 84322-4820.
W.L. Lindsay, Distinguished University Professor of Soil Chemistry, Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523
Arthur E. Martell, Distinguished Professor of Chemistry, Texas A&M University, Department of Chemistry, College Station, TX 77843-3255
David R. Parker, Associate Professor, Department of Soil and Environmental Sciences, University of California, Riverside, CA 92521
Robert C. Santore, Research Technician, Department of Civil & Environmental Engineering, Syracuse University, Syracuse, NY 13244-1190
William D. Schecher, Chief Researcher, Environmental Research Software, Hallowell, ME 04347
A. Paul Schwab, Associate Professor of Soil Physical Chemistry, Department of Agronomy, Kansas State University, Manhattan, KS 66502
Gregory R. Smith, Program Manager, Water Conservation Office, California Department of Water Resources, Sacramento, CA 95814
Robert M. Smith, Senior Research Associate, Texas A&M University, Department of Chemistry, College Station, TX 77843-3255
Garrison Sposito, Professor of Soil Physical Chemistry, Division of Ecosystem Sciences, University of California, Berkeley, CA 94720
Donald L. Suarez, Geochemist, U.S. Salinity Laboratory, USDA-ARS, Riverside, CA 92501
Kenneth K. Tanji, Professor of Hydrologic Science, University of California, LAWR-Hydrolic Science, Davis, CA 95616
R.J. Wagenet, Professor, Department of Soil, Crop and Atmospheric Sciences, Cornell University, Ithaca, NY 14853
J.H. Weare, University of California, San Diego, La Jolla, CA 92093