Determination of baseline element composition of lichens using samples from high elevations.

The results of a survey aimed at providing baseline element composition of lichens from unpolluted or very low
polluted areas are reported. Lichen samples collected at high elevation areas in Himalayas (Nepal), Mt. Kenya (Kenya)
and the Alps (Italy) were analyzed for their trace element content, mostly by INAA, allowing for a multi-element
analysis. The elemental composition of lichen samples was essentially influenced by natural occurrence, mainly airborne
soil dust. However, also anthropogenic input determined by long-distance atmospheric transport of pollutants was
involved for some highly volatile elements such as Br, Cd and Sb. To avoid the influence of soil contamination and air
pollution, and obtain baseline concentrations to be used as reference (the ‘‘natural’’ elemental composition of lichens),
the average of the lowest concentrations is suggested.