Acid Rain Overview

A raindrop in a pollutant-free atmosphere has, as we have seen, a pH of 5.6 as a result of the dissolution of C02. However, emissions of S02 and NO lead to conversion of these species during transport from their sources to acidic sulfate and nitrate, and their incorporation into cloud and rainwater. Addition of these acids lowers the rainwater pH, and the rain reaching the ground is acidic. 

The major foundations for our present understanding of acid rain and its effects were laid by Eville Gorham. On the basis of his research in England and Canada, Gorham showed as early as 1955 that much of the acidity of precipitation near industrial regions can be attributed to combustion emissions, that progressive acidification of surface waters can be traced to precipitation, and that the free acidity in soils receiving acid precipitation results primarily from sulfuric acid. 

Scandinavian and European studies, including the Norwegian Interdisciplinary Research Programme Acid Precipitation—Effects on Forest and Fish, and the study by the European Organization for Economic Cooperation and Development, elucidated the effects of acid rain on fish and forests and long-distance transport of pollutants in Europe. 

Brimblecombe (1977) and Cowling (1982) have provided excellent historical perspectives associated with the discovery of and attempts to deal with acid rain. 

FIGURE 20.8 Map of the global pattern of precipitation acidity as determined by the Background Air Pollution Monitoring Program of the World Meteorological Organization [after Whelpdale and Miller (1989)]. 

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Lane, C. N. 2003. Acid Rain Overview and Abstracts. New York Nova Science Publishers. Covering both wet and dry deposition of acid rain, this work offers both a background article and over 900 abstracts and book citations. Title, author, and subject indexes are provided for easy access. 

An overview of acid rain monitoring activities in North America shows several national and regional programs in operation in the United States,... 

EPA. Acid Rain Program www.epa.gov/docs/ acidrain/overview.html. 

Trees can be impacted by acid rain in any number of ways and these effects can be classified as either direct or indirectClJ. The following discussion will present an overview of the many v ays acid rain could affect woody plants specifically as well as unfinished wood products. 

Acid in the Environment Lessons Learned and Future Prospects provides an overview of the important science and policy issues pertaining to acid deposition. Acid in the Environment uses an interdisciplinary approach that focuses on important ecological impacts of acid deposition, the transboundary nature of the pollutants that cause acid rain, and domestic and international policies designed to reduce the emission of these pollutants. By emphasizing issues such as the scientific lessons learned from acid dep-... 

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