les away from Knoxville, Tennessee, the air pollution created from the large population in the city has carried over and has had very grave effects on the national park. "The damage the mountains sustain comes primarily from acid rain and ozone created from sulfur and nitrogen emissions. Clouds over the Smokies can be a thousand times more acidic than natural rainfall--and more than 30 species of trees and plants in the park show injury from ozone, including black cherry, yellow poplar, blackberry, and milkweed (Tennesen 1997)."At Grand Canyon National Park in Arizona, the affects of air pollution aren't necessarily shown through plant life because there isn't much of a plant life in the area. The area in Arizona is known for it's spectacular rock formations within the enormous canyon. Because of air pollution, those beautiful formations cannot always be seen. "Pollution diminishes the views on 90 percent of the days. On some days, visitors to the South Rim can see only half as far as those who toured the park when it was dedicated in 1919 (Tennesen 1997)." Carl Bowman, an air quality scientist at the national park said that, "Instead of those huge erosional forms and brilliant colors, you often see only vague blue masses." Besides the effects that air pollution has had on the Grand Canyon and Great Smoky Mountains, it has had an amazing effect on the plant life of nearly all of the national parks in the country. The levels of ozone and acid rain seem to have the most detrimental effects on the plant communities in these parks. "Ozone affects the leaves of a number of plants, producing purple to dark brown stippling that can hinder plant photosynthesis, physiology, and growth (Tennesen 1997)." Acid rain has been shown to have terrible effects on the underground systems of plants rather than their above ground structures. "Acid rain enters the soil and leaches away calcium, potassium, and magnesium, essential nutrients for plants. It can...
