Impact of the sulphur dioxide sources in the Kola Peninsula on air quality in northernmost Europe

Abstract An account is presented of sulphur pollution in northernmost continental Europe, based on analysis of recent observations and on dispersion model calculations. To complement the routine daily observations made at background stations, SO 2 has also been measured using an hourly registering monitor at Janiskoski in the Russian Kola Peninsula. Sulphur dioxide emissions from the Kola Peninsula, totalling 600 Gg (10 3 tonnes) yr −1 , have a dominant impact on SO 2 concentrations and S deposition over large areas, producing an environmental load exceeding the thresholds for potential detrimental effects. The major part of these emissions is produced by two non-ferrous smelters. Due to these sources, SO 2 concentrations vary considerably within the study area, from the low “remote background” values to pollution episodes with −100 μ g(SO 2 )m −3 as an hourly average, depending on wind direction. High concentrations also occur in summer, providing a great potential for dry deposition and suggesting that exposure is a highly episodic process. On an annual basis, dry deposition predominates over wet deposition. Precipitation acidity is related mainly to sulphate, and neutralization by alkaline cations is exceptionally low in the north. According to model calculations, a potentially critical deposition of 0.3 g(S) m −2 yr −1 is exceeded over an area of 150,000 km 2 , 32,000 km 2 of which are in Finland and 19,000 km 2 in Norway. Within this area the contribution of smelter emissions to sulphur deposition ranges from 40% to almost 100%.