Since it falls silently and is such an integral part of our world, acid precipitation at first seems less detrimental than other types of pollutants. Unfortunately, this simply makes the problem more insidious, and although research into the subject is relatively new, the findings far from complete, several causes and effect relationships have definitely been linked to acid rain.
Many high altitude lakes in New York's Adirondacks, for example, once renowned for their excellent fishing, are now devoid of fish, due to a drastic drop in the pH of the lake water. In all, the Environmental Protection Agency has counted 90 lakes in the region that are too acidic to support their native fish population. Damage to other life forms is more intangible and difficult to gauge.
"There are definite and obvious effects of acid rain, though without thorough research we can't assume that all are detrimental," observed Dr. James Hornbeck, a forest hydrologist who works for the U.S. Forest Service at the New England Forest Experimental Station in Durham, N.H. One fact is clear, however, according to Hornbeck: New Hampshire's precipitation is among the most acid in the United States.
Under normal circumstances, rain, snow, sleet and fog measure about pH 5.5, or slightly acidic. The strength of an acid is measured in terms of this pH factor, which is based on the concentration of a solution's hydrogenions. PH7 is neutral, while 1 is extremely caustic. The pH scale is logrithmic, however, meaning that a one point decrease in pH represents a 10-fold increase in acidity, or a drop of two signifies that the acidity level increases by 100.
Although slightly acid rain is a natural phenomena, the problem is aggravated by industrial activity. Dissolved carbon dioxide causes all precipitation to have a slightly acid quality, but oxides of sulphur oxides generated by utilities and industrial boilers that burn coal, a problem that is destined to intensify as the nation seeks to move away from its dependence on oil. The remainder is linked to nitrogen oxides emitted from fossil fuel power plants and automobile emissions.
Unfortunately for New Englanders, who live in a relatively unpolluted environment, the regions immediately surrounding industrial centers are not the most adversely affected by acid rain. Upper New York State, Vermont, New Hampshire, and Maine receive some of the most acid rain in the country, and it is as a result of the steady westerly winds that carry pollutants eastward from the industrial centers of the Midwest.
Once oxides accumulate in the upper atmosphere over Ohio, for example, they are carried east to their point of deposition through precipitation. The irony of acid rain, though, is that in part the phenomena has been created by environmental regulations in recent years. In order to clarify the air in industrial communities, the U.S. government required taller emission stacks to allow the wind to disperse pollutants further distances. The taller stacks mean that oxides stay aloft longer, are transformed into acids, and can travel 1000 miles or more before falling to earth in the from of acid rain or snow.
This long distance pollution had caused political trouble between states as well as nations. Several states, New York and Pennsylvania among them, have considered suing Ohio, which has the nation's largest total annual sulfur dioxide emission rate, to tighten its clean air standards. Others are urging the U.S. Environmental Protection Agency to assume a stronger stance on the issue. Officials of the U.S. and Canada were so concerned by the acid rain issue that over 700 of them attended the Action Seminar on Acid Precipitation last November in Toronto. The result of the gathering was a resolution encouraging both countries to cut atmospheric levels of sulphur and nitrogen oxides by half within the next decade.
New Hampshire has assumed more of a wait-and-see attitude, though research into the subject of acid precipitation has been underway for several years. "New Hampshire is making a definite effort to stay abreast of the situation," noted Dr. Hornbeck, who for the last three years, has been involved in a research project at the Hubbard Brook Experimental Forest in West Thornton, just north of the town of Plymouth. He added that the N.H. Water Supply and Pollution Control Board maintains equipment of its own to monitor acid rain, and would be in a position to initiate legal action if it is deemed necessary in the future.
Hornbeck's project at Hubbard Brook is two-fold, and is sponsored by the U.S.F.S. and the National Science Foundation in cooperation with Yale and Cornell Universities. "The first aspect of the project is simply to monitor the water pH in several streams," Hornbeck explained, "and ours is part of a nationwide system called the National Atmospheric Deposition Program." Hornbeck elaborated that 35 stations participate across the U.S. "Basically we examine the chemistry of precipitation, and measure its pH," he added. Significantly, New Hampshire registers among the most acid precipitation in the country. "Along with two or three other stations, we have the lowest pH, well below five. In the three years that we have monitored precipitation, the pH has not dropped noticeably, however," he stated.
The other studies being conducted at Hubbard Brook involve gauging the direct effect of acid rain on the aquatic ecosystem of a stream. To do this, acid is dripped into the stream to lower its pH from the normal 5.5 to around 4, and then insects, algae growth, and the water chemistry are monitored. At the same time, researchers have changed the pH of another stream to 7, and are conducting similar tests. "It is too early to draw definite conclusions," Hornbeck noted, "though there are obvious effects in the acid stream. To determine the impact, you have to look at the entire food chain, and that's extremely complex and time consuming."
Still, the effect of acid rain on lakes, particularly in the Adirondacks and because of many physical similarities with those in the White Mountains, is already apparent. In addition, as Hornbeck explained, high altitude lakes are particularly vulnerable. "In low lying areas, extensive forest cover around lakes acts to filter acid precipitation before it enters the groundwater," he stated. "Higher up, this isn't the case. There simply isn't the forest canopy to buffer the impact of acid rain." Ironically, New Hampshire's granite bedrock, which has always helped protect the purity of its high lakes and ponds, is now adding to the problem of acidity, since granite is deficient in limestone and similar compounds needed to neutralize acid.
One way to counteract acidity in these lakes is simply to add ground limestone, a program that New York has undertaken in recent years. In a few cases, liming and restocking have revitalized dead ponds, but the remedy has obvious limitations. First, the logistics of adding tons of lime to countless lakes and ponds are staggering, and since the lime wears off after several years, it is virtually useless in large bodies of water.
Still, determining and coping with the impact of acid rain on lakes is less complex than measuring its effect on forests and other terrestrial life, according to Dr. Hornbeck. "Lakes are immediately vulnerable and the effects of acid rain obvious," he said, "while understanding what's happening to our forest ecosystem is extremely complex." In addition to his work at Hubbard Brook, Hornbeck has been involved with a study to measure the effect of acid rain as it passes through the forest canopy. "While it is drastic, it's still hard to pinpoint the exact impact," he remarked. "Acid rain quickly washes minerals and nutrients out of the foliage and weakens the system, but this is where our ability to isolate the individual impact acid rain has in the situation." As to the effect on humans and other animals, little if any information is available.
In recent months the subject has begun to receive considerable publicity, however, and as Dr. Hornbeck noted, "As a result, we're beginning to have more money available for research." President Carter, for example, recently authorized 10 million dollars for acid rain research. "There's much we don't know, but our knowledge is expanding rapidly," Hornbeck reflected. "The time is coming, probably within the next five or 10 years, when we will have many of the details."
The obvious long-term solution to acid rain is to eliminate the source of the problem - air pollution - though in light of the current energy situation and President' Carter's insistence on burning more coal to counteract the country's dependence on imported oil, it seems unlikely that will happen in the near future. In the meantime, acid precipitation will fall, and New Englanders will have to learn to cope with the hard rain.
"There's no question that acid rain presents the potential for great harm, but rather than jumping to conclusions, we have to qualify its impact through research," Dr. Hornbeck pointed out. "We don't want to employ scare tactics, but we do know that N.H.'s precipitation is as acid as anywhere in the nation. We're at the end of the pipeline. There are no easy solutions to the problem, and first we have to understand all aspects of the situation."