Long-term deposition patterns of airborne wastes in the North-East of Estonia

The deposition loads of fly ash and sulfur have been high in the NE Estonia since the late fifties, when the oil shale energetics, chemical and cement industry achieved the remarkable extent. The combined effects of both pollutants have seriously damaged sensitive ecosystems (forest on podzolic soils and bog). The main effects are related with alkalization due to accumulation of fly ash components and the Sphagnum growth inhibition due to sulfur load. These effects have the time scale of several years or even more. The pollution loads have been changed during recent 40 years due to launching and reconstruction of enterprises (incl. purification systems) and variations of production capacity. First representative data on air pollution deposition originate from the middle of eighties. Only model estimations could be used to quantify the deposition fluxes before that time, as well as for assessing the future scenarios. The air pollution dispersion and deposition model AEROPOL is used for this purpose. The estimations are based on air pollution emissions per production unit and climatic average dispersion conditions. The model estimations are compared with available measured values. The deposition loads for a possible development in the future are estimated.