Air Pollution Urban Smog. As a result of steps taken pursuant to the 1990 Clean Air Act amendments, ozone concentrations in the park have been reduced. Nevertheless, exceedances of the health standards still occur, and each summer park visitors must be advised on occasion to avoid strenuous exercises such as bicycling, hiking, and jogging-the reasons many come to the park to begin with. High levels of ozone in the air threaten not only human health but vegetation as well. Research has shown several plant species to be sensitive to ambient levels of ozone, and injury has been documented to native vegetation within the park.
Additional monitoring is needed to determine long-term trends.
Nitrogen and sulfur oxides emitted primarily from power plants have resulted in the acidification of numerous lakes and streams as well as soils throughout the Northeast. The potential for loss of fish, defoliation, and ecosystem balance that has occurred elsewhere as a result of acidification is high. Additional research and monitoring are needed to determine the long-term implications of acidic deposition at Acadia. Mercury Contamination of Fish. Power plants, hazardous waste, and medical incinerators contribute to harmful levels of mercury in the fish in Acadia's lakes and ponds.