UT's Energy, Environment and Resources Center Presents 

Smoky Mountain

Resource Issues in Great Smoky Mountains National Park 

 SUMMER 2001
Vol. 2 No. 1

AIR
The Acid Test

HUMAN INTERACTION
Back to the Future

WILDLIFE
Deviant Behavior

WATER
Aquatic Insects on the Frontline

VEGETATION
Managing the Land

BIODIVERSITY
Campaign to Identify Smokies' Species Continues

Editor: David Brill; Assistant Editor: Constance Griffith; Writers: Kris Christen, Lisa Byerley Gary, Elise LeQuire, Dennis McCarthy, and Becky Nichols. Graphic Designer: Lisa Byerley Gary.

SIGHTLINE is published on behalf of
Great Smoky Mountains National Park
by the
Energy, Environment and Resources Center (EERC)
at the
University of Tennessee.

EERC conducts research designed to promote real-world solutions to problems in the fields of energy, environment, technology, and economic development.

For additional information, write EERC, 311 Conference Center Building, The University of Tennessee, Knoxville, TN 37996-4134, call 865-974-4251, or visit our Web site at http://eerc.ra.utk.edu.

SIGHTLINE is sponsored by:

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The Acid Test

Acid deposition may be damanging the Smokies' soil, water, plants and animals

BY ELISE LeQUIRE

Rising from 2,000 feet to over 6,000 in elevation, the Noland Divide watershed is not the highest point in the Smokies-that distinction belongs to nearby Clingmans Dome-but it sets another, less impressive record. It has the highest rate of chronic acid deposition of any monitored site in the United States.

Noland Divide is one of eight watersheds in Great Smoky Mountains National Park monitored since 1980 to determine trends in the health of complex ecosystems. To track trends of acid deposition, for example, researchers measure acidic input-from rain, snow, dry particles, and clouds-and output, based on soil and water samples.

Researchers consider Noland Divide typical of high-elevation forests in the Park. "Noland appears to be chronically acidic, as are a few other places, and higher episodic levels of acidity occur during major storm events," says Steve Moore, fisheries biologist for the Park.

While higher-elevation streams and forests are naturally more sensitive to acid deposition than are ecosystems at lower elevations, the dramatic increases in acidity over time have a human origin. "High levels of acidity in precipitation and high acidity in aquatic ecosystems wouldn't be there if it weren't for fossil-fuel combustion," Moore says.

Commonly known as acid rain, a term coined by Scottish chemist Angus Smith in the 19th century, acid deposition is the result of pollutants-primarily sulfur dioxide and nitrogen oxides from fossil fuel combustion-being released into the atmosphere during electric power generation, motor vehicle operation, and industrial processes. These pollutants undergo chemical changes in the atmosphere to form secondary pollutants-sulfates, nitrates, and ozone-that can harm human health, corrode car paint, deteriorate limestone and marble structures, form regional haze, and damage soils, streams, and vegetation. The resulting acid deposition affects soil chemistry and fertility, streamwater quality, and forest health, says Jim Renfro, air quality specialist at Great Smoky Mountains National Park.

The National Park Service (NPS) has been monitoring acid deposition for more than 20 years, Renfro says, in part to fulfill the original mandate of the NPS Organic Act of 1916 to "conserve the scenery and the natural and historic objects and the wildlife therein...by such means as will leave them unimpaired for the enjoyment of future generations." The NPS gained more specific powers to enforce that mandate, with the 1977 Clean Air Act amendments designating Class I areas-national parks with more than 6,000 acres and wilderness areas with more than 5,000 acres-that would receive special protection from air pollution. Those amendments also direct federal land managers of Class I areas to aggressively protect air-quality related values of lands under their jurisdiction and to err on the side of protection.

Sensitive Systems
Acid deposition occurs as wet precipitation in rain and snow; in cloud water that bathes the forests at higher elevations; and as dry particles that fall on vegetation, soil, and surface water. While natural precipitation is slightly acidic, with a pH of around 5.5 (a pH of 7 is neutral), the average pH of rain in the Park is 4.5, 10 times more acidic than unpolluted precipitation, Renfro says. In addition, "episodic events such as major rain storms and snow melts can cause huge increases in acidity in streams, and clouds in the Park's high-elevation forests sometimes reach a pH of 2.0," which is more acidic than vinegar and more than 1,000 times more acidic than normal rainfall.

What happens when precipitation reaches the Earth depends in part on the soil chemistry and underlying bedrock. In the valleys, deeper layers of topsoil, as well as alkaline limestone substrates, help neutralize the acids. At higher elevations, a number of natural conditions-including thinner soils, tree litter, and aging forests-make the streams and soil naturally more acidic. These more sensitive ecosystems are at higher risk of damage from short- and long-term effects of acid deposition.