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 coastal
Victoria Land (Antarctica) during 1991 - 2001. Overall average concentrations
of trace elements except Cd were the lowest ever reported for lichens of the
genus Umbilicaria. Specifically, the mean level of Pb in lichen from granitic
rock (0.46 +/- 0.18 mg/g-1 dry wt) was more than four times lower than the
lowest record in Arctic lichens. No impact of local human activities was
detected, but the elemental composition of U. decussata was affected by
entrapment of soil of rock dust particles and probably by uptake of soluble
elements from substrate.

Relationship between elements and their distributions patterns in the study
area indicated that the marine environment is the main source of major ions and
perhaps of Cd in lichens. Accumulation of P was detected in samples from
coastal sites frequented by seabirds. Although the present results can be taken
as baseline levels of major and trace elements in Antarctic U. decussata from
substrates with very different geochemical features, further research is
necessary to evaluate the relative element contribution from each substrate
with respect to those from snow, marine aerosol, salt encrustation and guano.