Relation between sulphur concentrations in the Scots pine needles and the air in northernmost Europe

The SO2 emissions from the Kola Peninsula in Arctic Russia (totalling around 600 Gg(SO2) yr(-1) at the beginning of the 1990s) produce an atmospheric SO2 concentration gradient to the northernmost Europe. This gradient covers the range from >50 mu g m(-3) in the vicinity of the sources to 1 mu g m(-3) in Finnish Lapland. In the present study, the measured sulphur concentrations in Scots pine needles were compared with the estimated distribution of atmospheric SO2. The total sulphur concentrations in the needles ranged from 741 to 2017 mg kg(-1). Strongly elevated concentrations (> 1200 mg kg(-1)) were found within 40 km from the smelters corresponding to an area where the annual mean atmospheric SO2 concentration exceeded 10 mu g m(-3). The foliar sulphur concentrations (total, organic and inorganic) show a high correlation with the estimated mean SO2 concentration distribution in the air. Consequently the foliar sulphur concentrations reflected the atmospheric sulphur load well. The data presented here show that uptake via stomata is an important deposition pathway also in the arctic conditions with a short growing season.