Temporal trends in long-range atmospheric transport of heavy metals to Norway

Abstract

The temporal trends in atmospheric deposition of some heavy metals in Norway are presented and discussed on the basis of two different approaches: The use of moss samples during the last 25 years to monitor atmospheric deposition, and the analysis of peat cores to study long time trends. Deposition surveys based on moss sampling have been carried out 5 times since 1977, each time covering nearly 500 sites all over the country. The southernmost part is particularly exposed to V, Zn, As, Se, Mo, Cd, In, Sn, Sb, Pb, and Bi due to long-range transport from source areas elsewhere in Europe. Deposition of these elements however has declined substantially over this period. In the case of Pb the 2000 level is less than 10% of that in 1977. Long-term trends have been studied by means of dated peat cores from 6 ombrotrophic bogs in different part of the country, covering a period of about 3000 years. The elements typical of long-range atmospheric transport show quite coherent depth distributions in the peat. Stable lead isotope ratios indicate that air pollution was the dominant source of lead deposition during the entire period.