Recent trends in chemical composition of bulk precipitation at Estonian monitoring stations 1994–2001 |
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Authors: | K Treier K Pajuste J Frey |
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Institution: | aInstitute of Geography, University of Tartu, Vanemuise 46, 51014, Estonia;bEstonian Environmental Research Centre, Marja 4D, 10617 Tallinn Estonia |
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Abstract: | Monthly and annual means of main anions (SO42−, NO3−, Cl−) and summed base cations (Ca2+, Mg2+, K+, Na+) in bulk precipitation were studied at 10 stations during an 8-year monitoring period. The data showed statistically significant decreasing trends in most cases. Average declines of mean annual volume-weighted concentrations for both anions and cations were about two-fold. Despite the decrease, the loads of S and cations are still relatively high in Estonia (about 4–14 kg S ha−1 and 0.6–1.2 keq ha−1, respectively) compared with the loads in Finland and Sweden. Estimated linear decline trends followed the same pattern as annually combusted oil shale from Estonian power plants and emissions of SO2 and fly ash. Recent trends in chemical composition of bulk precipitation at the monitoring stations reflected economic changes in Estonia as well as transboundary fluxes from neighbouring countries. |
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Keywords: | Atmospheric deposition Oil shale emissions Precipitation chemistry Monitoring Concentrations Loads Economic change |
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