Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, September 2, 1993 TAG: 9309020006
SECTION: NATIONAL/INTERNATIONAL PAGE: A-6 EDITION: METRO
SOURCE: Associated Press
DATELINE: CHATTANOOGA, TENN. LENGTH: Medium
Discolored plant leaves and dying trees are signs that too many toxins are flowing into the region from industrial sites north and south of the mountain chain. A federal forest officials says the Great Smoky Mountain section of the Appalachians is suffering the most.
Jim Renfro, air resource specialist for the National Park Service, said the Great Smoky Mountains have consistently registered the highest pollution and the most ozone and acid rain damage in the nation.
Part of the reason is that they include some of the highest peaks in the Appalachians - the nation's oldest mountain chain. The Appalachians stretch from Canada to central Alabama, and include the Blue Ridge, Smoky and Cumberland mountains.
Air currents carry several million tons of sulfates, nitrates, carbon monoxide and volatile organic compounds into the region.
The dirty air tends to stay in the southern Appalachians because the South has more days of stagnant air than anywhere else in the county. Because of the height and structure of the mountains, the pollutants become trapped by air masses of different temperatures and pressures, Renfro said.
He said ozone and acid rain, both byproducts of burning fuel to run cars, power plants and industries, are creating yellowed, purpled and prematurely aged leaves on plants.
He said those symptoms could forecast potential problems to health, biodiversity and even the economy of the region.
Burning the fuels produces sulfur dioxide and nitrogen oxides. When the chemicals react in the atmosphere, they form weak acids. Some return to Earth as acid rain and acid air particles.
Others, in sunlight, combine with volatile organic compounds and form ground-level ozone.
Renfro said ozone in the atmosphere is helpful; it absorbs some of the sun's dangerous ultraviolet rays.
But ground-level ozone is harmful because it enters plants through their leaves and damages internal cells that contain chlorophyll. This slows and eventually can stop photosynthesis, the growth process of plants.
Renfro said federally mandated safety levels for ground-level ozone in the southern Appalachians often push the limit. The level is based on what is safe for human exposure - not plant exposure.
Researchers have seen an increased rate of dieback in southern Appalachian forests where ozone levels are at half the federal standard, Renfro said.
Ninety native mountain plant species show ozone-like damage, he said. Researchers examined 35 of those plants; ozone was found to be the culprit in 30.
Studies show damage to black cherry, tulip popular and sassafras trees; and milkweed plants. Renfro said these plants could be affected to the point of extinction.
Plants also are affected by high levels of acid rain. Rainfall in the southern Appalachians is five times as acidic as normal and fog is more severe, Renfro said.
He said acid rain hurts plants by damaging their leaves and roots. It also can change the chemistry in streams and lakes, sometimes killing aquatic and plant life, he said.
by CNB