Heavy metal concentrations in a lichen of Mt. Rainier and Olympic National Parks, Washington, USA

Abstract

It is commonly assumed that the larger National Parks in the United States are pristine places which can provide baseline environmental conditions for comparisons with more developed areas. However, recently it has been recognized that many National Pars are threatened by atmospheric pollution. Until 1985, a copper smelter at Tacoma, Washington, 50 km northwest of Mount Rainier National Park, Washington emitted 30 tons of lead annually, along with high levels of arsenic and other metals. Other nearby sources of airborne heavy metals include a coal-fired generating plant at Centralia, 80 km west of the Park, and automobiles within the Seattle-Tacoma metropolitan area 50-100 km to the northwest. Heavy metals are a potential threat because they may effect ecosystems by decreasing nutrient cycling rates and impairing overall productivity. The objective of this study was to test the hypothesis that an arboreal lichen (Alectoria sarmentosa) within Mt. Rainier National Park contained elevated levels of heavy metals from these sources. This lichen species was chosen because it is common throughout forested areas of the region. Olympic National Park was selected as an experimental control area because it is located on the relatively undeveloped Olympic Penisula west of Seattle-Tacoma.