SULFUR AND NITROGEN DEPOSITION IN NORWAY, STATUS AND TRENDS

The total deposition of sulphur (S) and nitrogen (N) components in Nor way during the period 1988-1992 has been estimated on the basis of mea surement data of air- and precipitation chemistry from the national mo nitoring network. There are large regional variations in depositions w ith highest values in the southwestern part of Norway. Time series ana lysis of annual mean concentrations of sulphur dioxide (SO2) and sulph ate (SO4-) in air, non marine SO4-, nitrate (NO3-) and ammonium (NH4+) in precipitation, shows a significant reduction in the S concentratio ns both in air and precipitation. In precipitation the concentrations are reduced by 30-45 percent in Southern Norway and 45-55 percent in C entral and Northern Norway. Even larger reductions are observed in air concentrations with 50-65 percent reduction in Southern Norway and 65 -88 percent reduction further north. For N components there are genera lly no significant trends in concentration levels nor in precipitation or air. The observed trends are comparable with reported trends in em ission.