Metal levels in an epiphytic lichen as indicators of air quality in a suburb of Helsinki, Finland

The levels of Cd, Cu, Fe, Hg, Mn, Ni, Pb and Zn were measured in epiphytic lichens Hypogymnia physodes in a suburban area of Helsinki, Finland. The metal levels were near the background values or slightly higher. The concentrations of Cd, Fe and Zn were compared with results from a previous monitoring survey. The concentrations of Cd had increased significantly from 1980 to 2007 but were still at the background level. The levels of Fe and Zn had decreased during that period. The distribution of metals was in most cases rather even but land use explained partly the distribution of some of the metals studied.