Temporal patterns of metal deposition at various scales in Austria during the last two decades

Austria has been participating in the “European Moss Survey” within the UN-ECE ICP-vegetation since 1991. Three consecutive sampling periods in 1995, 2000 and 2005 were performed. Five moss species at 220 sampling sites (2.5 sites 1000 km−2) were analysed for Al, As, Cd, Co, Cr, Cu, Fe, Hg, Ni, Mo, Pb, V, and Zn concentrations. According to the retrospective analysis by 3-year-old moss segments, this investigation covered deposition in the period between 1989 and 2005. A relocation of sampling sites (within 2 km2) was necessary for <10% of the sites within the overall period. On an Austria-wide scale all metals with the exception of Co, Cd and Hg showed a significant decrease of concentrations in the observed period. On a regional or site scale a large deviation from this general trend could be found, leading to significant differences between regions for many elements (e.g. for Co, Pb and Zn). Even continuous increases of metal deposition could be found at several sites (e.g. for Mo and Cu). This implies that pollution levels at different scales should be looked at in a differentiated way even in times of generally decreasing metal deposition.