LICHENS AS MONITORS OF POLLUTANT ELEMENTS AT PERMANENT SITES IN MARYLAND AND VIRGINIA

Concentrations of sulfur, nitrogen, and seven metal elements are repor ted for the lichen Flavoparmelia baltimorensis from three monitoring s tations in Maryland and Virginia. At Plummers Island, Maryland, 15 km from the center of Washington, D. C, lichens have been collected for n early 100 years. The other two stations, Bear Island, Maryland (21 km) and Stony Man Mountain, Virginia (120 km), were established in the 19 70's by Mason Hale to help document changes in ambient air quality in the Washington, D.C area. Concentrations of cadmium, chromium, nickel, zinc, and lead were consistently highest at Plummers Island and lowes t at Stony Man Mountain; concentrations of the other four elements (ni trogen, sulfur, aluminum, and copper) were also consistently higher at Plummers Island than at Stony Man Mountain. Recent collections, in 19 88 and 1992, revealed marked reductions in the concentration of all ni ne elements except aluminum al all three stations, providing limited, but encouraging, signs of improved air quality in the region.