Changes in trace metal deposition in Austria between 1991 and 2000

Mosses have been employed to monitor atmospheric heavy metal deposition in Austria since 1991, following the method of international studies using Hylocomium splendens, Pleurozium schreberi, Hypnum cupressiforme and Abietinella abientina as monitoring species. In 1995 and 2000, samples were taken at approx. 230 sites, accounting for 3.5 sampling points per 1000 km², distributed on a regular grid. In 1991 only 43 sites were analyzed in regard to national deposition patterns. Al, Co, Cr, Cu, Fe, Hg, Mo, Ni, Pb, V, and Zn were analyzed by ICP-AES, As by FIAS, and Cd by AAS. On a national scale the average concentrations of Cd, Mo, Ni, Pb, and V were found to decrease significantly. For As, Co, Cr, Fe, and Zn, minor reductions in deposition were observed. For Cu, and Hg, a distinct increase in concentrations since 1991 was detected. The increase in Cu is probably associated with increasing traffic emissions; the reasons for the Hg increase remain unclear. On a local scale (single sampling sites) the concentrations varied. There were cases of elements sharply decreasing nationally but increasing locally, the possible causes being increasing emissions from local sources like traffic, local combustion or local industry; another possible reason is contamination of samples by soil dust. The results are discussed in an international context.