Acid Deposition

The majority of this book was written in 1983-84 while the senior author was a Visiting Scientist at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. We believe that the approach to the problem of acid deposition effects on soils and waters developed during this collaboration contains ele ments that are significantly different from most prior work in this area. Some of the material and the software used in the development of these concepts stem from earlier individual efforts of the authors. However, what we believe to be the more significant concepts concerning the processes by which alkalinity may be developed in acid soil solutions, and by which acid deposition may contrib ute to the loss of this alkalinity, were the result of this collaboration. The ultimate usefulness of these concepts in understanding and dealing with various aspects of the problems associated with acid deposition cannot be adequately gauged at the present time. They must first withstand tests of con sistency with available observation, and of direct experimentation. It is our hope that dissemination through this book will facilitate this process within the scientific community. The authors wish to thank the administration of the Environmental Science Division at ORNL, and the College of Agricultural Sciences at Colorado State University for their support in arranging this collaboration. We also wish to express our appreciation for the financial support provided by EPA. Personal thanks are due to Dr.

Concern about acid deposition, commonly referred to as acid rain, as a widespread pollution problem with severe ecological consequences has heightened public awareness. Many authorities fear that acid deposition may be the worst environmental crisis of our industrialized society because of both the global implications and possible widespread, irreversible damage to lakes, soils, and forested ecosystems. Neither state nor international boundaries are exempt from the transport and deposition of airborne pollutants resulting from local and distant emission sources. The dilemma and debate will continue as long as society requires fossil fuels for its energy needs without regard to emission constraints. This book started as a modest attempt to provide a status report on atmospheric transport, the chemical processes which produce acidifying agents, and resultant ecological and economic consequences. The materials in this book have been substantially revised from those presented at the conference in 1983. It became obvious that additional chapters were required when sudden and profound changes occurring in European forests were reported. It is felt that perhaps such damages could be an early warning to forested ecosystems in the northeastern United States and Canada as well as other places throughout the world. Most importantly, it is essential that gained scientific knowledge be translated into required legislation - a section on Policy Issues was incorporated to address these concerns. It is hoped that the reader will become informed and concerned enough to be involved in ll this IIglobal debate. Donald D. Adams Halter P.

'Acid rain' is a broad term used to describe several ways that acids fall out of the atmosphere. A more precise term is acid deposition, which has two parts: wet and dry. Wet deposition refers to acidic rain, fog, and snow. As this acidic water flows over and through the ground, it affects a variety of plants and animals. The strength of the effects depends on many factors, including how acidic the water is, the chemistry and buffering capacity of the soils involved, and the types of fish, trees, and other living things that rely on the water. Dry deposition refers to acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. The wind blows these acidic particles and gases onto buildings, cars, homes, and trees. Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms. When that happens, the runoff water adds those acids to the acid rain, making the combination more acidic than the falling rain alone. Prevailing winds blow the compounds that cause both wet and dry acid deposition across state and national borders, and sometimes over hundreds of miles. This new book combines an excellent background article with over 900 abstracts and book citations. Easy access is provided by title, author, and subject indexes.

The subject of acid deposition remains one of the most urgent of our contemporary environmental problems. Research programmes are continually redefming our understanding of cause and effect and hence the continuing need for a timely and authoritative series addressing these issues. This volume seeks to review and defme our contemporary understanding of acid deposition by reference to new international data and as a consequence assist the definition of our future research requirements and policy developments. International contributions to the volume are drawn from the Federal Republic of Germany, the U.S.A., Canada, Brazil, Switzerland, Austria, Israel, France and the United Kingdom. Some of these nations have experienced acid deposition on a regional scale for considerable periods of time; for others the phenomenon is an emerging problem. This collection of papers has been compiled by invitation to eminent members of the acid deposition research community and by selection from a carefully targeted call for papers. It is primarily designed to meet the needs of researchers, lecturers and postgraduate students in environmental disciplines and for environmental policy makers. It is of interest to professionals in related disciplines and essential as a reference text for libraries. The volume is divided into four broad themes: Emissions, chemistry and deposition; Ecosystem effects (freshwater, soils and forest systems); Effects on structural materials; Mitigation, control and management. Each of these sections provides an overview of contemporary understanding, presents new experimental or field evidence and provides guidance for our future research agenda.