Acid Rain Changes Lake and Riverine Ecology

Scientists connected increased acidity in forest lakes with decreased fish populations. This scientific determination led to renewed attempts to control and monitor air and water pollution to combat the effects of acid rain on the environment.

Summary of Event

During the 1950’s and early 1960’s, a network of measuring stations in Scandinavia indicated that the average content of acid and sulfate in rain and snow was increasing. In 1959, a Scandinavian fisheries inspector, A. Dannevig Dannevig, A. , reported the disappearance of fish in streams and lakes of southern Norway and southwestern Sweden and recognized the relationship between the increasingly acidic rain and the fish populations. On the heels of these observations, long-term measurements of atmospheric precipitation and snow melt from across Europe showed that a growing plume of increasingly acid rain was spreading across northwestern Europe. Observations such as these prompted American scientists to examine the acidity of their own water resources. Acid rain
[kw]Acid Rain Changes Lake and Riverine Ecology (1950’s—mid-1960’s)
[kw]Rain Changes Lake and Riverine Ecology, Acid (1950’s—mid-1960’s)
[kw]Lake and Riverine Ecology, Acid Rain Changes (1950’s—mid-1960’s)
[kw]Riverine Ecology, Acid Rain Changes Lake and (1950’s—mid-1960’s)
[kw]Ecology, Acid Rain Changes Lake and Riverine (1950’s—mid-1960’s)
Acid rain
[g]Europe;1950’s—mid-1960’s: Acid Rain Changes Lake and Riverine Ecology[03100]
[g]Norway;1950’s—mid-1960’s: Acid Rain Changes Lake and Riverine Ecology[03100]
[g]Sweden;1950’s—mid-1960’s: Acid Rain Changes Lake and Riverine Ecology[03100]
[c]Environmental issues;1950’s—mid-1960’s: Acid Rain Changes Lake and Riverine Ecology[03100]
Gorham, Eville
Likens, Gene
Carter, Jimmy

Continuous measurement of rain and snow samples beginning in 1964 at Hubbard Brook Experimental Forest Hubbard Brook Experimental Forest in New Hampshire showed that precipitation was quite acidic, with pH counts ranging from 4.03 to 4.19. (Rain is naturally acidic because carbon dioxide in the atmosphere dissolves in rainwater to make a weak solution of carbonic acid. The pH scale, which was developed in 1923, indicates the extent of acidity. It is a logarithmic scale, which means that solutions with a pH of 4.0 are ten times more acidic than solutions with a pH of 5.0. Carbon dioxide dissolved in pure water has a pH of about 5.6.)

Acid rain was not a new problem. Not even the term “acid rain” was new. It was first used in 1852, but it was not until Gene Likens, an ecologist at Cornell University, popularized it in 1972 that it became commonly used. Acid rain had been associated with industrial emissions since 1661, and scientists in Leeds, England, demonstrated in 1911 that the acidity of rain decreased the farther one got from the city center. They associated this with burning coal. By 1924, it was known that burning coal acidified rain and that such rain could affect the chemical composition of nearby lakes and the growth of nearby crops.

Various investigators were studying atmospheric acidity by 1952. Beginning in 1955, an English ecologist, Eville Gorham, wrote extensively about acidification, the different sources of acidity, and their influence on geochemical processes. He built much of the foundation for understanding the causes and consequences of acidity in aquatic ecosystems. By the early 1960’s, Gorham and his colleagues had done much to further understanding of acid rain. Its influence on ecosystems, however, was not known.

Several disastrous air pollution episodes, such as the London killer smog of 1952 in which four thousand people died, prompted government initiatives in Europe, Canada, and the United States to control air pollution. One initiative was to construct tall stacks to carry emissions away from the immediate vicinity of coal-burning plants. The effect was to disperse acid-forming compounds over a broad area and to create a mechanism that would carry them great distances downwind. A network to measure atmospheric precipitation, including acidity, was established in Sweden by Hans Egnér Egnér, Hans in 1948. At about this time, the first monitoring programs in the United States were also established, although, unlike the Scandinavian program, these were sporadic and short term. These monitoring programs began to detect acidic precipitation shortly afterward, in northwestern Europe in the early 1950’s and in the eastern United States in the late 1950’s.

Svante Ódén Ódén, Svante , a soil scientist at the Agricultural College of Uppsala, Sweden, started a Scandinavian network for water surface chemistry in 1961. The information from these and other monitoring stations showed that precipitation in surface water was becoming more acidic. Ódén observed that changing acidity was a regional and temporal problem in Europe and that the acidity in Scandinavia could be readily attributed to sulfur emissions in England and central Europe. Between 1956 and 1966, Ódén noted that acid precipitation was growing with an ever-widening plume of increasing acidity.

Lake surveys in the Adirondack Mountains of the United States and Sweden showed relationships between acidity and declining fish populations. Unfortunately, prior to 1962, no data for acid precipitation was available for the northeastern United States. Scientists, however, found indications of increased acidity when they reexamined old water-quality data. Measurements in New York lakes from 1918 to 1929 suggested that they had much lower acidity than existed in acid rain. For example, the acidity of a large, clear-water lake in the Adirondack Mountains of New York changed appreciably between 1938 and 1959, as the pH level fell from between 6.6 and 7.2 to between 3.9 and 5.8.

Fish loss in the Adirondacks was documented in the 1920’s and the 1930’s. After assessing older data, two scientists at Cornell University, Likens and Charles Cogbill Cogbill, Charles , detected a large area of the Northeast with diminished precipitation in 1955 and 1956. Data from a decade later showed, like the Scandinavian example, that the area of acidic precipitation was increasing eastward and south. Clearly, processes that affected acid rain in Europe were also at work in the United States.


There was a ten-year lag in public awareness of acid rain and its ecological significance. Acid rain was recognized in the mid-1950’s, but until the first reports of fish kill were publicized by the Norwegian press in 1966, little happened. The Scandinavian results were presented to the Organization for Economic Cooperation and Development Organization for Economic Cooperation and Development (OECD) in 1969, and, following two reports in the early 1970’s from Sweden (“Air Pollution Across National Boundaries”) “Air Pollution Across National Boundaries” (government report)[Air Pollution Across National Boundaries] and Norway (“Acid Precipitation: Effects on Forests and Fish”), “Acid Precipitation” (government report)[Acid Precipitation] public interest became aroused.

Acid rain occurred as early as 1952 in the northeastern United States. For example, the White Mountains of New Hampshire were receiving rain with a pH of less than 4.5 since 1955. There was little debate that rainfall was indeed becoming more acid. There was, however, considerable debate over whether it caused the ecological effects that had been attributed to it.

Two points of view developed with respect to acid rain research. The first was that acid rain represented an environmental problem requiring legislative action. In this view, the problem had been acute since the mid-1950’s and was growing. Acid rain, it was believed, resulted from the consumption of fossil fuels. The acids produced (mostly sulfuric and nitric acid) could be transported great distances and cause environmental damage when they were deposited.

Fish surveys in the Adirondacks and Sweden showed a direct correlation between the acidity of lakes and the fish population. In comparing pH in the White Mountains of New Hampshire from the late 1930’s to 1979, scientists found that the pH had declined considerably and that some acidification had occurred. Historical fish declines had been recorded in the 1920’s and 1930’s in the Adirondacks and among the Tovdal River salmon in Norway.

Critics of this cause-and-effect argument suggested that acid conditions in lakes and streams were a result of changed land use and that long-term analysis of historical data showed nothing that could be specifically attributed to acid rain. Some lakes in areas receiving acid rain had clearly become more acidic, but others in the same regions had become less acidic or had not changed. Because of the paucity of historical data in the Adirondack Mountains, lakes devoid of fish may have always been devoid of fish—the lack of fish was not necessarily an effect of acid rain.

Acidification by acid rain, they contended, was superimposed on long-term acidification caused by changes in land use and changes in vegetation. Soil formation in the humid, temperate climates is an acidifying process, and the amount of acid in soil is enormous compared to what is deposited by precipitation. The soils in the Adirondack Mountains, New England, eastern Canada, and southern Scandinavia were already more acid than the acidity of rain they received.

The evidence for acid rain causing the acidification of lakes and streams on a regional basis was not conclusive and remained circumstantial. Many of the regions at risk had undergone land use change since the turn of the century. Forest removal and burning can increase pH, and the reversion of land to acid heath in Norway, for example, was producing areas of increasingly acid soil typical of any attempt to re-create original forest conditions in these environments.

Continued research has done much to refine what is known about acid rain and the areas most sensitive to acid rain. The areas most affected by acid rain are those that are underlain by granite (which weathers slowly), that are weakly acidic to begin with, and that have noncalcareous soil (low in calcium and carbonate) with little buffering capacity. In cases where watersheds drain limestone and marine deposits, alkaline lakes can form in regions receiving acid rain. Lakes have been undergoing acidification since the glaciers retreated in North America and northern Europe, but the sediment data suggested that this process had accelerated since the 1950’s.

The source of acid rain can be hundreds of miles from the area in which it falls. These sources include fossil fuels (coal, oil), industry (smelting), automobile exhaust, and nitrogen fertilization in agriculture. Acid rain has been mostly related to increased release of sulfur and nitrogen, which are converted to sulfuric acid and nitric acid in the atmosphere. Tall stacks at power plants decrease ground level effects but increase the spread. Since the residence time of sulfur in air is two to four days, during that period it can travel more than six hundred miles. Consequently, acid rain in Scandinavia has been attributed to heavy industry in the Ruhr Valley in Germany, while acid rain in New York has been attributed to the industrial Midwest.

Acid rain affects aquatic reproduction. At pH levels between 5.0 and 6.0, reproduction of many aquatic organisms is inhibited, and at a pH of less than 5.0, many freshwater fish become extinct. This is partly because the availability of phytoplankton and zooplankton for fish to consume declines in acid lakes. Acid rain affects soil fertility by leaching nutrients and by immobilizing phosphorus, an essential plant nutrient. Aluminum toxicity becomes a problem when pH falls below 6.0. Acid rain also damages leaves. Terrestrial plants, however, vary greatly in sensitivity to and recovery from acid rain. Injury occurs in the most susceptible growth stages, such as during reproduction. Economic damage to crops and trees by acid rain can also occur.

The evidence for the potential seriousness of acid rain was compelling, and legislative action was initiated to contend with it. A presidential initiative was announced by Jimmy Carter on August 2, 1979, in his second environmental message, which called for a ten-year, $10 million per-year research program on the causes and consequences of acid rain. The first acid rain bill was introduced into the Senate by New York senator Daniel Patrick Moynihan Moynihan, Daniel Patrick in 1979 and was passed in 1980. The greatest obstacle to legislative action in the United States was the issue of financial burden for acid rain. Those who paid for pollution abatement were not necessarily those who bore the costs of environmental damage. Acid rain

Further Reading

  • Abbasi, S. A., P. Krishnakumari, and F. I. Khan. Hot Topics: Everyday Environmental Concerns. New York: Oxford University Press, 1999. Explication and analysis of the major environmental issues of the turn of the twenty-first century, particularly acid rain and global warming. Bibliographic references and index.
  • Cowgill, Charles. “Acid Precipitation: A Review.” In Environmental Problems and Solutions, edited by T. Nejat Veziroglu. New York: Hemisphere, 1989. A balanced treatment of the topic from a historical perspective. Clearly describes the differing viewpoints of various groups on the subject of acid rain.
  • Grove, Noel. “Air: An Atmosphere of Uncertainty.” National Geographic 171 (April, 1987): 502-537. A good place to start reading on the subject. The overview of chemical compounds that contribute to acid rain and other types of air pollution will aid in understanding more complex discussions of the topic.
  • Krug, Edward, and Charles Frink. “Acid Rain on Acid Soil: A New Perspective.” Science 221 (August, 1983): 520-525. A valuable counterpoint to the premise that acid lakes come from acid rain.
  • Likens, Gene. “Acid Rain.” Environment 14 (March, 1972): 33-40. A readable summary of acid rain from its discovery to its consequences. Generally unbiased but clearly favors action to address the issue.
  • Torrens, Ian. “Acid Rain: An International Perspective.” In Acid Rain: Economic Assessment, edited by Paulette Mandelbaum. New York: Plenum Press, 1985. A good overview of how acid rain developed into a global issue and what types of international action have developed in response to it.
  • Wilcher, Marshall. The Politics of Acid Rain. Brookfield, Vt.: Avebury, 1989. Provides an overview of national policy on acid rain and how that policy develops in different political systems. Occasionally dry and academic.

Black Wednesday Demonstrates Dangers of Smog

First Water Pollution Control Act Is Passed

Smog Kills Thousands of Londoners

Congress Passes the Air Pollution Control Act

Congress Amends the Water Pollution Control Act

Clean Air Act Grants Federal Authority to Regulate Air Pollution

Congress Strengthens Water Laws

Pesticide Poisons the Rhine River

Polluted Cuyahoga River Bursts into Flames