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In 1992 we reported an indication of global increase of atmospheric mercury concentrations obtained from the measurements of total gaseous mercury (TGM) over the Atlantic Ocean during five ship cruises between 1977 and 1990 [Slemr and Langer, 1992]. The observed rate of concentration increase and its implications were consistent with previous measurements and the trends derived from analyses of dated peat bog and lake sediment records. To avoid uncertainties from the intermittent character of ship measurements and to obtain more detailed information about this trend, we have continuously monitored TGM concentrations at the summit of the Wank mountain (1780 m a.s.l.) near Garmisch‐Partenkirchen in southern Germany since March 1990. These measurements and the results of another cruise in 1994 indicate a significant change in the trend of global TGM concentration, with a decrease of about 22% in the years between 1990 and 1994. This decrease is most likely the result of reduction in coal consumption and control measures taken in the OECD countries.

SUMMARYThe present study was performed on mature Norway spruce trees {Picea abies L.) with needle losses in the range of 25-35 %. The trees were growing at three altitudes (870, 1270, and 1700 m above sea level) in a mountain forest in the Calcareous Alps of Bavaria. The objectives were to assess the role of climate and pollution in addition to nutrient disorders for damage to spruce trees. During the growing season the average temperature was up to 5 °C lower and the average ozone concentration was about twofold higher at the high altitude in comparison to the low altitude (13 and 18 °C, and 60 and 35 nl T^ ozone, respectively); the average NO^ and SO^ concentrations did not exceed 5 nl 1"^ Foliar analysis of pollutants did not indicate critical levels of Pb, Cd, Cl, F and S. Biometrical parameters, foliar element composition, pigment and protein content of the needles were determined during four seasons. Average dry:fresh weight ratios, specific needle weights, projected needle areas, soluble protein and carotenoid contents were similar within the 20 % range for needles from all three altitudes. Foliar analysis of nutrients indicated a low nutrient status especially for nitrogen, and showed a phosphorus deficiency in needles from the three sites. The chlorophyll content of the needles decreased with increasing altitude. Since nutrient imbalances were greatest in needles from the lowest site, it was concluded that the greater damage to spruce trees and lower chlorophyll content of the needles at altitudes > 1000 m above sea level were not caused by nutrient disorders.