Elemental composition of the lichen Umbilicaria decussata

Total concentrations of major and trace elements were determined in thalli of the epilithic lichen Umbilicaria decussata from 37 habitats in Victoria Land (continental Antarctica). Average concentrations of Pb, Cu, Zn, Cr, Mn and Fe were among the lowest ever reported for lichens of genus Umbilicari a. On the contrary, Cd and Hg concentrations fell within the same range or were higher than those usually measured in samples from remote areas of the southern and northern hemispheres. No impact of local or remote human acti vities was detected. Comparison between average metal concentrations in U. decussata samples collected in 1989 and 1999 did not show significant varia tions, and this result was assumed to be indicative of negligible changes i n the environmental biogeochemistry of Antarctic terrestrial ecosystems. Th e ad/sbsorption of soil and rock dust particles, atmospheric depositions, m arine aerosols, guano of seabirds, and the uptake of soluble elements from widespread salt encrustations and/or rock minerals are the main sources of major and trace elements for epilithelic lichens in continental Antarctica. Although the present results can be taken as baseline levels, further rese arch is necessary in view of the expected effects of climatic changes on el ement bioavailability in ice-free areas of Antarctica.