Testimony on Acid Rain: The Phenomenon, Its Effects, and Recommendations for Action by Dr. Ellis B. Cowling Chairman, National Atmospheric Deposition Program Associate Dean for Research, School of Forest Resources Assistant Director, North Carolina Agricultural Research Service North Carolina State University Prepared for the United States Senate 10:30 AM, Wednesday, May 28, 1980 Statement by Dr. Ellis B. Cowling, Associate Dean for Research and Professor of Plant Pathology and Forest Resources, North Carolina State University, Raleigh North Carolina 27650. Prepared for hearings by the Committee on Energy and Natural Resources, United States Senate, May 28, 1980. For the past 20 years I have been a Professor of Plant Pathology at Yale and at North Carolina State Universities. A significant portion of my personal research and that of my graduate students has been on effects of acid precipitation on agricultural crops and forest trees. For the past 3 years I have served as chairman of the National Atmospheric Deposition Program -- a regional program of research sponsored by the State Agricultural Experiment Stations and several other agencies including the Department of Agriculture, the U.S. Geological Survey, the U.S. Environmental Protection Agency, the Department of Energy, the National Atmospheric and Oceanic Administration, and others. The objectives of the National Atmospheric Deposition Program (NADP) are as folows: 1) to determine spatial and temporal trends in the deposition from the atmosphere of beneficial and injurious substances into ecosystems in various regions of the United States, and 2) to organize and coordinate research on the effects of atmospheric deposition on the productivity of agricultural crops, forests, range lands, wet lands, and surface waters. In this later connection, EPA has recently established a 5-year Cooperative Agreement with North Carolina State University to manage a large part of its programs of research on the biological effects of acid precipitation. Our responsibilities under this Agreement include synthesis and integration of results from research conducted both in this country and abroad. -2 In December of 1978, the NADP submitted a report to the Council on Environmental Quality entitled: "A National Program for Assessing the Problem of Atmospheric Deposition (Acid Rain)." This report provided the principal basis for the Presidential Initiative on Acid Rain announced by President Carter in his Second Environmental Message. In this report we included: 1) an assessment of the scope of available knowledge about atmospheric deposition and its effects on agricultural lands, forests, ranges, parks, surface waters, and aquatic life in the United States; and 2) recommendations for a coordinated program of research and monitoring necessary to serve as a basis for the intelligent management of atmospheric emissions and for the amelioration of the adverse effects of atmospheric deposition and acid rain on plant and animal life. Many of the ideas presented later in this written testimony are developed more fully within the pages of that report to CEQ and in a paper entitled "From Research to Public Policy: Progress in Scientific and Public Understanding of Acid Precipitation and its Biological Effects." I have provided both of these items in sufficient copies for use by the members and staff of this Committee. Also attached to this written testimony are four other items: 1) a list of government agencies concerned with acid precipitation; 2) a selected list of references; 3) a description of the NADP monitoring program; and 4) a "Status Report on Acid Precipitation". These four items summarize the background of scientific thought and agency commitments from which I will respond in my verbal testimony to the specific questions raised in Sections I and II of the Agenda for these Hearings. The major points of my testimony may be summarized briefly as follows: Acid rain has become a dominant feature of man-induced change in the chemical climate of the earth. But the increasing acidity of rain is only part of the changing chemistry of precipitation, dry particulate matter, aerosols, and gases in the -3 major industrial nations of the world. Recent biological research on acid precipitation has demonstrated that 1) atmospheric deposition contains both beneficial nutrients and injurious substances; 2) plants, animals, and ecosystems vary greatly in susceptibility, tolerance, and adaptability to changes in atmospheric deposition; 3) injury is most likely when rapid changes in the chemical climate coincide with a vulnerable life form or life stage; 4) increasing acidity of precipitation has caused extinction of fish and other changes in species composition at all topic levels in oligotrophic lakes in northern Europe and eastern North America; and 5) simulated acid rain has caused leaching of nutrients from soil and both direct and indirect injury to terrestrial vegetation; with rare exceptions, however, economic damage to crops by naturally occurring acid rains has not been demonstrated to date. These results show why the comprehensive Acid Rain Assessment Program called for in the President's Second Environmental Message is so crucially important in maintaining the quality of surface waters, the health of fish, and the productivity of forests, agricultural crops, and range lands in this country and in Canada. These results also show why, in my considered judgement, the following general conclusions about public policy appear to be appropriate: 1) As of May of 1980, the effects of acid precipitation and associated metal ion toxicity on aquatic ecosystems are sufficiently well understood that preliminary formulation of energy conservation, regulatory, and ameliorative policies can be initiated now. 2) As of this same month, however, potential effects on terrestrial organisms are still too poorly understood to permit the development of wise regulatory policies at this time. 66-112 O-80--2 Acid Precipitation as Part of a General Phenomenon of Atmospheric Deposition Precipitation formed in an atmosphere relatively free from natural or anthropogenic sources of contamination would have a pH of about 5.6 due to dissolution of gaseous CO2. Thus, acid precipitation has been defined operationally as rain or snow with a pH value below 5.6. But acidity in precipitation must be understood as a reflection not only of the amounts of substances yielding hydrogen ions (such as sulfuric, nitric, hydrochloric, and organic acids) but also of the total ionic balance between all the cations and anions in precipitation. Most of the substances dispersed in the atmosphere are at least partially soluble in water. These dissolved substances can be absorbed or assimilated by plants when precipitation is intercepted by vegetation. Since some of the substances dissolved in precipitation are beneficial while others are injurious to plants and animals, the net effect of atmospheric deposition can be beneficial or injurious depending on the chemical composition of the deposited matter, the duration and intensity of deposition episodes, the species and genetic characteristics of the organisms on which the substances are deposited, and the physiological condition, structure, phenology, and stage of maturity of the organisms. Direct injury to living organisms by acid precipitation is most likely when a particularly vulnerable life form (for example, lichens or fish) is exposed at a particularly vulnerable life stage (for example, the early stages of reproduction), and are growing in a poorly buffered environment (for example, sandy soils or oligotrophic lakes or bogs) during a season of the year when acid precipitation is most likely (for example, spring rains). |