The effect of large anthropogenic particulate emissions on atmospheric aerosols, deposition and bioindicators in the eastern Gulf of Finland region

The effect of the emissions from large oil shale fuelled power plants and a cement factory in Estonia on the elemental concentration of atmospheric ae rosols, deposition, elemental composition of mosses and ecological effects on mosses, lichens and pine trees in the eastern Gulf of Finland region has been studied. In addition to chemical analysis, fly ash, moss and aerosol samples were analysed by a scanning electron microscope with an energy disp ersive X-ray spectrometer (SEM/EDS). The massive particulate calcium emissi ons, approximately 60 kton/year (1992), is clearly observed in the aerosols , deposition and mosses. The calcium deposition is largest next to the Russ ian border downwind from the power plants and in south-eastern part of Finl and. This deposition has decreased due to the application of dust removal s ystems at the particulate emission sources. At the Virolahti EMEP station a pproximately 140 km north from the emission sources, elevated elemental atm ospheric aerosol concentrations are observed for Al, Ca, Fe, K and Si and d uring episodes many trace elements, such as As, Br, Mo, Ni, Ph and V. The a cidification of the soil is negligible because of the high content of basic cations in the deposition. Visible symptoms on pine trees are negligible. However, in moss samples close to the power plants, up to 25% of the leaf s urface was covered by particles. Many epiphytic lichen species do not toler ate basic stemflow and on the other hand most species are also very sensiti ve for the SO2 content in air. Consequently a large lichen desert is found in an area of 2500 km(2) in the vicinity of the power plants with only one out of the investigated 12 species growing. (C) 2000 Elsevier Science B.V. All rights reserved.