Improving the use of lichens as biomonitors of atmospheric metal pollution

The data reported on this study supported the hypothesis that the absence o f the lichen Ramalina fastigiata near a copper mine site located on the sou th of Portugal was related to toxic levels of Cu-dust near the centre of th e mine. Lichen biodiversity reflected the impact of the copper-mine dust em issions which were more widespread towards the east, correlated with wind d irection and frequency. The chemical analysis of R. fastigiata collected at different distances and in different directions from the mine showed that Cu, K and Mg were derived from the centre of the mine site, confirming thus as the major source of atmospheric dust. Total inhibition of PSII photoche mical reactions occurred in R. fastigiata both under field and controlled c onditions, when intracellular Cu concentrations exceeded a threshold of app roximately 2.0 mu mol g(-1). No samples of this species were found under fi eld conditions beyond the Cu threshold. Thus, the fluorescence parameter F- v/F-m proved to be a good estimator of the survival capacity of R. fastigia ta under field conditions and thus a useful parameter in determining the se nsitivity of the lichens (photobiont) to Cu pollution. The intracellular lo cation of Cu allowed an explanation of the physiological changes and the su rvival of the species in the surroundings of the copper-mine. (C) 1999 Else vier Science B.V. All rights reserved.