Temporal changes in nitrogen pollution in northeastern Estonia.
During the last 5 decades the northeastern part of Estonia (the region where oil shale and the chemical industry are located) has been subjected to pollution with acidic compounds. In 1981-1988 the yearly mean nitrogen (N) deposition load was up to 11.1 kg ha(-1). This N pollution level combined with the deposition of sulphur (S) could have seriously endangered the environment, but the simultaneous emission of strongly alkaline fly ash restrained acidification processes. After 1989-1991 the situation changed, and in 1994-1996 the N deposition load in northeastern Estonia remained within the range of 2.6 to 6.6 kg ha(-1) year(-1) and that of S within 2 to 50 kg ha(-1) year(-1). Because the fly ash deposition is permanently decreasing, more sensitive lichens and mosses can be subjected to critical N+S loads in the future. The proportion of oil shale industry in total emission of NOx in Estonia from stationary sources equals approximately 65 to 75%. During 1996-2000 the yearly mean concentration of NO2 in the air of towns increased from 9 to 12 to 16 to 29 g m(-3). The emission of N compounds was mainly caused by N oxides in flue gases from power plants, as well as ammonia and carbamide discharges from chemical plants. In 1988-1990 the estimated yearly total emission of NOx (as NO2 equivalent) was about 18 to 18.6 thousand t and in 1994-2000, 9.9 to 11.8 thousand t.
Liblik
V
V
Tallinn University of Educational Sciences, Institute of Ecology, North-East Estonian Department, Jõhvi, Estonia. valdo@ecoviro.johvi.ee
D000393:Air Pollutants / Q000378:metabolism* / Q000506:poisoning; D000397:Air Pollution / Q000032:analysis / Q000517:prevention & control / Q000706:statistics & numerical data; D044002:Bryophyta / Q000187:drug effects / Q000254:growth & development; D002617:Chemical Industry / Q000706:statistics & numerical data / Q000639:trends; D004777:Environment; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data; D004957:Estonia; D008011:Lichens / Q000187:drug effects / Q000254:growth & development; D009584:Nitrogen / Q000378:metabolism* / Q000506:poisoning; D012989:Soil Pollutants / Q000032:analysis / Q000506:poisoning; D013455:Sulfur / Q000378:metabolism / Q000506:poisoning; D001335:Vehicle Emissions / Q000032:analysis / Q000506:poisoning / Q000517:prevention & control
D000393:Air Pollutants; D012989:Soil Pollutants; D001335:Vehicle Emissions; D013455:Sulfur; D009584:Nitrogen