Acidic Precipitation

This volume contains papers presented at a NATO Advanced Research Institute, sponsored by their Eco-Sciences Panel, on "The effects of acid precipitation on vegetation and soils," held at Toronto, Canada from May 22-26, 1978. The organizing expenses and greater part of the expenses of the speakers and chair~en were provided by N.A.T.O. The scientific programme was planned by T. C. Hutchinson together with an international planning committee of G. Abrahamsen (Norway), G. Likens (U.S.A.), F.E. Last (U.K.), C.O. Tamm (Sweden) and B. Ulrich (W. Germany). Many of the dimensions of the 'acid rain' problem are common to countries of northern Europe and North America. The developing awareness over the past ten years of the international nature of the acid rain phenomenon has lead to studies documenting damaging effects on susceptible freshwater bodies. Large areas of the Canadian Pre-Cambrian Shield, with its extension into the United States, and the granitic areas of southern Norwayand Sweden contain lakes which are in the process of acidification. The biological resources of these affected areas are of considerable national concern. However, while clearly damaging effects of acidification on freshwater systems have been well documented, the impact of acid precipitation on terrestrial systems has not been so well understood.

'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.

Since the beginning of the 1980's, research has continued to clarify and improve our understanding of the problern of the ecological impact of acidic precipitation. From September 15-20, 1985, Canada convened the the Muskoka Symposium on Acidic Precipitation to review progress and help chart the direction of future studies. The Conference was held in central Ontario, Canada, a region of heavy sulphate deposition where aquatic effects are evident. Approximately 700 people attended, over 500 of whom were research scientists. Over 400 papers were presented. Nearly 200 of the papers are included in these proceedings, which tagether give the present state of the art of acid rain research. The Conference focused on atmospheric science and aquatic and terrestrial effects. I have made some general observations on progress in clarifying issues and linkages between these areas of research. Out standing issues which require a great deal more work are identified. These are my views, influenced by personal bias and limited by my expertise. Atmospheric Seiences Three aspects were covered: measurement techniques, the actual measure ments, and source-receptor relationships.

"awareness" of the world's citizens and encourage governments to devote more attention and resources to address this issue. The series editors thank the international panel of contributors for bringing this timely series into completion. We also wish to acknowledge the very insightful input of the following colleagues: Prof. A. L. Page of the University of California, Prof. T . C. Hutchinson of the University of Toronto , and Dr. Steve Lindberg of the Oak Ridge National Laboratory. We also wish to thank the superb effort and cooperation of the volume editors in handling their respective volumes. The constructive criticisms of chapter review ers also deserve much appreciation. Finally, we wish to convey our appreciation to my secretary, Ms. Brenda Rosier, and my technician, Ms. Claire Carlson, for their very able assistance in various aspects of this series. Aiken, South Carolina Domy C. Adriano Coordinating Editor Preface to Acidic Precipitation, Volume 5 (Advances in Environmental Science) Acidification research has been ongoing for several decades. It was not until the 1980s, however, that scientists began to recognize the complex ity of the factors causing the decline in forest growth and deterioration of fish populations in acidified lakes. The general feeling, based on correla tive research, was that long-range transported air pollution was the main cause. Proof, however, was difficult to obtain because of complex interac tions of various stress factors including natural ones.

"awareness" of the world's citizens and encourage governments to devote more attention and resources to address this issue. The series editors thank the international panel of contributors for bringing this timely series into completion. We also wish to acknowledge the very insightful input of the following colleagues: Prof. A.L. Page of the University of California, Prof. T.C. Hutchinson of the University of Toronto, and Dr. Steve Lindberg of the Oak Ridge National Laboratory. We also wish to thank the superb effort and cooperation of the volume editors in handling their respective volumes. The constructive criticisms of chapter review ers also deserve much appreciation. Finally, we wish to convey our appreciation to my secretary, Ms. Brenda Rosier, and my technician, Ms. Claire Carlson, for their very able assistance in various aspects of this series. Aiken, South Carolina Domy C. Adriano Coordinating Editor Preface to Acidic Precipitation, Volume 1 (Advances in Environmental Science) As a result of pioneering research in the 1960s and because of the perceived and acidic real environmental effects described during the ensuing years, the terms rain, acidic deposition, or acidic precipitation have become commonplace in the scientific and popular literature. In the last decade, governments throughout the world have responded to public pressure and to the concerns of the scientific community by establishing research programs on national and international scales.