Metal determination by EDXRF in lichens. A contribution to pollutants monitoring.

Samples of Evernia prunastri, collected in a mountainous zone, were exposed in urban and highly industrialized areas in order to monitor the atmospheric pollution. Amounts of Cr, Mn, Fe, Ni, Cu, Zn, and Pb were determined by EDXRF spectrometry in secondary target excitation mode and in the thin film approach. An increase in metal concentrations was noted on all sites with time exposition increases, but the highest final amounts were observed on those thalli mounted near a steel works. The washing procedure influenced the concentration of all the elements as previously verified on Pseudevernia furfuracea.