Acid rain is the common name for acidic deposits that fall to Earth from the atmosphere. The term was coined in 1872 by English chemist Robert Angus Smith to describe the acidic precipitation in Manchester, England. Today scientists study both wet and dry acidic deposits. Although there are natural sources of acid in the atmosphere, acid rain is primarily caused by emissions of sulfur dioxide (SO2…
Natural sources of sulfate in the atmosphere include ocean spray, volcanic emissions, and readily oxidized hydrogen sulfide released from the decomposition of organic matter found in the Earth. Natural sources of nitrogen or nitrates include NO5 produced by microorganisms in soils, by lightning during thunderstorms, and by forest fires. Scientists generally speculate that one-third of the sulfur a…
Several factors contribute to the impact of acid rain on an area. Transport systems—primarily the movement of air—distribute acid emissions in definite patterns around the planet. The movement of air masses transports emitted pollutants many miles, during which the pollutants are transformed into sulfuric and nitric acid by mixing with clouds of water. In the United States a typical …
In nature, the combination of rain and oxides is part of a natural balance that nourishes plants and aquatic life. However, when the balance is upset, the results to the environment can be harmful and destructive. (See Table 7.1.) TABLE 7.1 Effect of acid rain on human health and selected ecosystems and anticipated recovery benefits Although pH levels vary considerably from one body of wat…
Scientific research on acid rain was sporadic and largely focused on local problems until the late 1960s, when Scandinavian scientists began more systematic studies. Acid precipitation in North America was not identified until 1972, when scientists found that precipitation was acidic in eastern North America, especially in northeastern and eastern Canada. In 1975 the First International Symposium …
In 1980 Congress established NAPAP to study the causes and effects of acid deposition. About 2,000 scientists worked with an elaborate multimillion-dollar computer model in an eight-year, $570 million undertaking. In 1988 NAPAP produced an overwhelming 6,000-page report on its findings, including: The report concluded, however, that the incidence of serious acidification was more limited than orig…
Each year the EPA publishes a report detailing the progress achieved by the Acid Rain Program. The latest report is titled Acid Rain Program, 2002 Progress Report and was published in November 2003. The report notes that in 2002 there were 3,208 electric generating units subject to the SO2 provisions of the Acid Rain Program. They emitted 10.2 million tons of SO2 into the air as shown in Figure 7.…
The EPA reports that ecosystems harmed by acid rain deposition can take a long time to fully recover even after harmful emissions cease. The most chronic aquatic problems can take years to be resolved. Forest health is even slower to improve following decreases in emissions, taking decades to recover from damage by acid deposition. Finally, soil nutrient reserves (such as calcium) can take centuri…
Because of the transport properties of acid rain, it is not a localized problem. Emissions can originate hundreds of miles from where acid deposition occurs. Canadian authorities estimate that more than 30 percent of the acid rain that falls in Canada is due to U.S. emission sources. In Europe pollutants are carried from the smokestacks of the United Kingdom over Sweden. In southwestern Germany ma…
Every year the Gallup Organization polls Americans about their attitudes regarding environmental issues. The most recent poll was conducted in March 2004. As shown in Figure 1.8 in Chapter 1, acid rain ranked last among the environmental problems considered during the poll. Only 20 percent of respondents expressed a great deal of worry about acid rain. Table 7.3 shows a dramatic decline in concern…
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