Baseline concentrations of elements in the Antarctic macrolichen Umbilicaria decussata

Total concentrations of major and trace elements were determined in samples of the epilithic lichen Umbilicaria decussata from 24 ice-free areas in co astal Victoria Land (Antarctica). Overall average concentrations of trace e lements except Cd were the lowest ever reported for lichens of the genus Um bilicaria. Specifically, the mean level of Pb in lichens from granitic rock s (0.46 +/- 0.18 mu g g(-1) dry wt) was more than four times lower than the lowest record in Arctic lichens. No impact of local human activities was d etected, but the elemental composition of U. decussata was affected by entr apment of soil or rock dust particles and probably by uptake of soluble ele ments from substrate. Relationships between elements and their distribution patterns in the study area indicated that the marine environment is the ma in source of major ions and perhaps of Cd in lichens. Accumulation of P was detected in samples from coastal sites frequented by seabirds. Although th e present results can be taken as baseline levels of major and trace elemen ts in Antarctic U. decussata from substrates with very different geochemica l features, further research is necessary to evaluate the relative element contribution from each substrate with respect to those from snow, marine ae rosol, salt encrustations and guano. (C) 1998 Elsevier Science Ltd. All rig hts reserved.