Charles Driscoll, director of the Syracuse University Environmental Systems Engineering Program, and international expert on the science of acid precipitation, gave a lecture, "Acid Rain and the Adirondacks: Diagnosis and Prognosis," on February 24. Driscoll discussed the impact of acid precipitation on the Adirondack Park, a subject he has been studying for nearly 30 years, as well as the outlook for the park's recovery.
Driscoll discussed how acid rain develops, particularly in the Adirondacks. He said that originally, acid rain was believed to be the result of emissions of sulfur dioxide mixing with water in the atmosphere to make precipitation acidic. Today, however, there are also many other known chemicals that contribute to acid rain, including nitrogen oxide and ammonia.
Because of wind patterns, the Adirondack Park has an "airshed" that includes most of the mid-Atlantic and the eastern part of the Midwest. Included in this airshed are seven of the nation's top 10 states for emission of sulfur dioxide, as well as many states with high emissions of nitrogen oxide, making the deposition of sulfate and nitrate in the park's air supply very high. The actual amount of acid rain that falls throughout the park is related to the elevation and precipitation of each area, so that different areas of the Adirondacks receive varying degrees of acid rain each year.
The severity of acid rain's terrestrial effects in the Adirondack Park, according to Driscoll, can be attributed to the shallow, sandy soil present there, which is unable to neutralize the acidity of the rain.
Acid rain negatively impacts soil quality by depleting the available pools of nutrients, such as calcium and magnesium, that trees use to support their growth and protect themselves from damage over the winter. Driscoll said that acid rain also mobilizes aluminum (already present in the soil,) making it into a dangerous toxin.
With 3000 lakes in the Adirondack Park, the aquatic impacts of acid rain are clearly an issue for the area's ecology.
In studies done by Driscoll and his colleagues, a quarter of the lakes in the park were found to be chronically acidic, meaning that they had a pH of 5 or less. The pH of a lake is very important to the lake's ability to sustain life, said Driscoll. In his research, he found that the number of different fish species living in a lake went down as the pH of the lake went down due to acid precipitation.
The more sensitive fish species die in these lakes because the acidity of the water and the presence of mobilized alumninum cause disruption to the salt and water balance in their blood. Many lakes in the Adirondacks are so acidic that they have, in fact, become fishless.
Driscoll said that there are two ways to deal with acid rain. One is source control, where the amount of sulfur dioxide and nitrogen oxide emissions are decreased, thus lowering the deposition of acid in the atmosphere. The other solution, mitigation, involves increasing the supply of calcium in the water and soil affected by acid rain, which raises its acid-neutralizing capacity. The increased calcium supply is achieved by spraying lime into the water of a lake or stream. While attempts at liming by Driscoll and his colleagues have proved somewhat effective, particularly when used on the subwatersheds of lakes, the process is very expensive. It also creates a risk of damaging local flora and fauna with the influx of lime. Source control, however, takes a long time to show its effects, while mitigation can lower the pH of a body of water relatively quickly.
The good news, said Driscoll, is that recent research shows that the lakes in the Adirondacks are gradually showing improvement. "If you had asked me to give this talk a year ago," he said, "I couldn't have given you that news." Driscoll and his colleagues have also developed a computer model to project the effects of different emission control plans on the Adirondacks. Emission controls such as those in the Clean Air Act, Driscoll said, have been suprisingly cost-effective and have obviously contributed to the recovery of areas such as the Adirondack Park. Mitigation through liming however, as Driscoll pointed out, can be an effective jump-start method to recovery in very badly damaged lakes.
The lecture was sponsored by Sophomore Seminar 220: "Forever Wild: The Cultural and Natural Histories of the Adirondack Park," which looks at the Adirondack Park from perspectives including its science, its history, and the public policy surrounding it.
--Caroline O'Shea '07
