Atmospheric background deposition of heavy metals in Denmark monitored by epiphytic cryptogams.
Samples of a moss (Hypnum cupressiforme) and of two lichens (Hypogymnia physodes, Lecanora conizaeoides) were collected from the trunks of beech (Fagus sylvatica) at 21 rural sites throughout Denmark. The samples were analysed for heavy metal content. The concentrations of Cd, Cr, Cu, Ni, Pb, V and Zn in the plant material reflected the regional atmospheric deposition of these elements, but the content of Fe and Mn did not. The three epiphytic species all showed the same regional variation in metal content. The concentration in Hypnum was usually the highest, followed by Hypogymnia and Lecanora. The concentration of most elements increased approximately 1.5 times from north-western Denmark to eastern and south-eastern Denmark. It was suggested that this gradient might result from a N-S gradient, modified by the superimposition of local pollution in the region of the Sound (Oresund).