Effects of altitude on element accumulation in alpine moss

We determined trace metal concentrations in mature living tissues of the moss Hylocomium splendens, at different altitude, in the south-eastern Alps of Italy. We hypothesized that if precipitation does not vary with altitude trace element concentrations in moss tissues will not be affected by altitude. Contrary to our hypothesis, element concentrations did vary with altitude even in the absence of any precipitation pattern related to elevation. In particular, concentrations of anthropogenic pollutants (especially Cd and Pb) peaked at mid altitude (1400-1800 m) where frequency of cloud cover was the highest. We concluded that the trace metal concentrations in alpine mosses can be regarded as a reliable estimate of total atmospheric deposition, i.e., including occult deposition by cloudwater. The latter may account for a significant fraction of the total deposition of anthropogenic trace metals, in close relation to cloud cover frequency.