PATTERNS IN TRACE-ELEMENTS IN LICHENS

Epiphytic lichens were sampled in a Dutch national monitoring survey, which was carried out twice within 5 yr. The samples were analyzed by neutron activation analysis. The lichen data sets were presented in plots of geographical concentration patterns. These gave insight in the possible location of pollution sources. Comparison of the lichen data sets showed changes in the (geographical) concentration patterns with time. For all elements the areas with enhanced concentration classes increased from 1982-1983 to 1986-1987. The most striking change in concentration pattern was found for Cd. The application of factor analysis techniques in interpreting the concentration data yielded the composition of the various polluting components, which may facilitate identification of the associated sources.