The sea as major source of ions to lichens in terrestrial ecosystems of Victoria Land

Lichens and mosses constitute the bulk of plant biomass in terrestrial ecosystems of continental Antarctica. On the hypothesis that cryptogams can be used as an early warning system to detect the effects of climatic changes on environmental biogeochemistry, we investigated the elemental composition and the main sources of soluble ions to the saxicolous lichen Unibilicaria decussata, in Victoria Land. Concentrations of major anions (Cl-, SO42-, NO3-) cations (Na+, Ca2+, Mg2+, NH4+) and trace elements (Al, Cu, Fe, Mn and Zn) were determined in lichens, snow, salt encrustations and wet filter papers laid on lichen supporting rocks. Enrichment Factors calculated using Na as marine reference element were close to I for most of analysed ions irrespectively of rock types. A crustal contribution of Ca, K and above all Cu was found in the lichen thalli growing on gabbro and ultramafic rocks. The uptake of marine ions in Umbilicaria thalli probably occurs directly from the snow and aerosols and indirectly through the solubilisation of salt encrustations on rock surfaces. Possible effects of predicted climatic changes on biogeochemistry of Antarctic terrestrial ecosystems were discussed.