U Magazine, Fall 1986

MY TURN

Acid rain threat looms

S ince his emergence on the planet, man has been at the mercy of the environment. Only recently has the environment - on a global or regional scale - been at the mercy of man. One example of man's impact is the high acidity of rainfall over large ar– eas of North Ame'rica and Europe. Atmospheric acids, the result of greatly increased emissions of sulfur and nitrogen oxides in highly indus– trialized areas, are responsible for much of the haze which shrouds many urban centers and threaten the magnificent vistas of the Southwest. They are also acidi– fying sensitive lakes, leaving them devoid of fish, and damaging buildings and monuments, including such treasures as the Acropolis, the Tuj Mahal, and the Co– logne Cathedral. More recently concern has been ex– pressed about a possible link between acid rain and damage to forests, such as is being observed in Europe and eastern North America. The problem is highly politicized and has created re– gional antagonism because acid forming pollutants may be transported hundreds of miles from their source be– fore returning to earth in such forms as acid rain . Thus, industrial centers in Ohio, Pennsylvania, and Indiana generate much of the acid deposition suspected of dam– aging fragile aquatic and forest ecosystems in the Adirondacks and New England. Although acids are carried to the surface in a variety of ways, including rain, fog, snow and as fine particles, the phenomenon is most commonly referred to simply as "acid rain." Because of the presence of carbon diox– ide and other naturally occurring acids in the atmos– phere, rainfall is expected to be somewhat acidic. How– ever, the rain in some areas of the Northeast is typically three to six times more acidic than would be expected on the basis of naturally occurring acids. On other occa– sions, it is more than 10 times as acidic. Globally about 60 percent of the sulfur oxides in the atmosphere are the result of natural sources. But in heavily industrialized areas as much as 90 percent is due to human activities - primarily the combustion of sulfur-containing coals in electrical utility and indus– trial boilers. Major sources of these pollutants are concentrated in the eastern part of the country. About 80 percent of the sulfur oxides and 60 percent of the nitrogen oxides are emitted in the 31 states bordering on or east of the Mis– sissippi River. A recent EPA study reveals that 9 percent of lakes sampled in the Northeast are acidic and 19 percent are highly vulnerable to future acidification. The study also

found a large number of high-risk lakes in the South– east. Concern that acid rain may be contributing to damage to forests is of more recent origin. The problem has been especially acute in West Germany where a 1984 survey found that 50 percent of the total forest area exhibited some symptoms of "Wald Sterben" - literally forest death. Symptoms range from the yellowing of needles to tree mortality. In the U.S., forest effects have been most noticeable in the Northeast. Over the past 15-20 years, red spruce in the high elevation forests of New York, Vermont and New Hampshire have experience pronounced dieback and decreased growth. More recently similar effects have been observed in the Great Smokey Mountains. The most commonly suggested remedy to the acid rain problem is pronounced reductions in the emissions of the major acid precursors - sulfur and nitrogen ox– ides. Legislation has been introduced - unsuccessfully - in the past several sessionss of Congress that would mandate substantial reductions in such emissions. Such reductions will be expensive. The Office of Tech– nology Assessment estimates a cost of $2-5 billion dol– lars per year depending upon the extent of reduction and the control strategy adopted. Some control strate– gies would lead to significantly higher utility rates in source states, and there could also be serious socioeco– nomic problems in areas of the Midwest and Northern Appalachia as a result of a shift from high- to low-sulfur coals. The Reagan administration has taken the position that we do not yet know enough about acid rain and its effects to justify costly emission control programs - a position that is strongly supported by the states that are the major sources of emissions. Can further study sharpen the focus of the acid rain issue enough to suggest action? Yes, but only with cer– tain risks. As a panel of scientists appointed by the Pres– ident to review the acid rain problem concluded: " It is the nature of the acid rain problem, that actions have to be taken despite incomplete knowledge ... If we take the conservative point of view that we must wait until the scientific knowledge is definitive, the accumulated depo– sition and the damage to the environment may reach the point of irreversibility." • Dr. Donald Peterson is a professor of chemistry. He holds doctoral and master's degrees from Carnegie In– stitute of Technology.

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