2

This report, prepared at the request of the Council on Environmental Quality, has two objectives: (1) To assess the present scope of available knowledge about atmospheric deposition and its effect on agricultural lands, forests, ranges, parks, surface waters, and aquatic life in the United States; and (2) to recommend 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 on plant and animal life. Such a coordinated program is essential to insure that the continuing economic development of the United States, especially with regard to a national energy policy, is environmentally sound.

Background

Acid precipitation is a major environmental problem on both sides of the Atlantic Ocean. It is considered the primary environmental threat in the Scandinavian countries and a source of marked concern to other northern European countries and Canada. In the United States, acid precipitation is one of two major environmental problems recognized by the President's Council of Environmental Quality.1 The increasing acidity of precipitation (Figure 1) has already caused measurable damage to aquatic ecosystems and has the potential for longer-term injury (over decades) to forest ecosystems; it can severely impoverish sensitive soils and degrade the natural ecosystems SO important to human welfare. The continuing, unchecked environmental degradation caused by acid precipitation could reach a stage where the damage to natural ecosystems would be irreversible.

Several earlier reviews of the acid-precipitation problem in North America (see text for references) have agreed on both the need for research and the area of necessary research. The time has come to stop talking and to implement a comprehensive and well-coordinated program of research and monitoring. The United States already lags well behind other nations (including Canada, Norway, and Sweden) despite the severe threat posed by acid precipitation to large areas of this country.

Terms of Reference

This document recommends a coordinated program of research and monitoring on the effects of atmospheric deposition in the United States.2 Research programs are, therefore, proposed to determine:

1The other is the build-up of atmospheric carbon dioxide with its long-term potential for profound climatic alteration.

2The processes that lead to atmospheric deposition (emission, transformation, and transport in the atmosphere) are the subject of a separate document prepared by A. P. Altshuller. The title and table of contents

of that report are given in the Appendix.

FIGURE 1 THE WEIGHTED ANNUAL AVERAGE OF PH OF PRECIPITATION

IN THE EASTERN UNITED STATES IN 1955-56 AND 1972-73. (LIKENS, 1976)

3

1.

2.

3.

The magnitude of atmospheric deposition (acids, organic substances, metals, and nutrients) in the United States; and

its subsequent effects on lakes, streams, wetlands, forests, agricultural lands, and other ecosystems; and

the importance of these effects to the welfare of the people of the United States.

This document covers atmospheric deposition and the nature and magnitude of its effects for all four types of substances (acids, metals, organics, and nutrients); however, the recommended research is "weighted" towards acid deposition. The recommended research on metals, organic substances, and nutrients is weighted towards determining the amounts of deposition because our knowledge of these substances is less complete.

Reliable research will give no "quick-and-easy" solutions to the problems of atmospheric deposition because lakes, forests, and agricultural and range ecosystems are complicated communities of organisms. The amount of time required to answer the key questions will vary from months to years. Key questions on the sensitivity of species, lakes, and soils to acidification can be answered relatively easily compared to the long-term questions of ecosystem stress and alteration. These differences in time, energy, and funding level are reflected in the diversity and duration (over 10 years) of the recommended research projects (Table 1).

Our research recommendations are the result of extensive reviews of past and current research on the phenomena and effects of atmospheric deposition. The ranking of the recommended research (Table 2) is based on factors relative to the specific effect:

4.

Is the impact ecological, economic, or recreational?

Four general types of research are recommended: (1) The measurement of spatial and temporal trends in atmospheric deposition, (2) calibrated watershed studies, (3) biological effects studies, and (4) economic assessment and criteria development. To succeed, the proposed research program must have a long-term commitment by the funding agencies. Specific aspects

of each of the four areas are outlined below.