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2.4. Acidification
Main reason for acidification is emission of sulphur and nitrogen
compounds (SO2, NOx and NH3) into
atmosphere. These compounds will decompose in precipitation and fall
back on the earth surface in the form of acid rain. Acid rains damage
forests, populations of waterbodies, cultural heritage. Largest pollution
sources of sulphur and nitrogen are energy production and industry,
although most of nitric oxides are emitted from transport and most
of ammonium from agriculture.
In 1990-1998 emissions of SO2 from stationary pollution
sources decreased in Estonia by 61.7% and emissions of NOx in 1987-1998
by 43% (figures 2.22 and 2.23). Decrease of emissions of sulphur dioxide
took place mainly due to the decrease of load of large power stations
as well as reduction of amounts of heavy fuel oil used for combustion
in boiler houses.
Figure 2.22. SO2
emissions from stationary pollution sources and transport in 1980-1998,
th. tons
Figure 2.23. NOx
emissions from stationary pollution sources and transport in 1987-1998,
th. tons
In 2000 Estonia joined the Convention on Long-Range Transboundary Air Pollution and its three protocols, which concern sulphur, nitrogen oxides and volatile organic compounds. Requirements of all those protocols have already been fulfilled in Estonia (to implement reductions of sulphur emissions or their transboundary fluxes by at least 30% at the latest by 1993 compared to the year 1980 and to stabilize emissions of nitrogen compounds on the level of 1987). Also a bill has been prepared for the joining with the protocol of the cooperative Programme for Monitoring and Evaluation of the Long-Range Transmission of air Pollutants in Europe (EMEP), belonging to the convention. In 2001-2002 it is planned to join the protocol of further reduction of sulphur emissions, belonging to the convention.
Figures 2.24 and 2.25 show territorial distribution of emissions of
sulphur and nitrogen in Estonia, with density 50x50 km (requirement
of EMEP). The same data have been submitted also to managing body
of EMEP. The figures show that the highest pollution load is in Ida-Virumaa,
where also larger energy and industrial companies of Estonia are located
(Eesti Energia Ltd Narva TPP’s, Kohtla-Järve and Ahtme TPP’s, oil
shale chemistry companies) and in Harjumaa and Tallinn (Iru TPP, Tallinna
Soojus Ltd etc.). This is confirmed also by precipitation monitoring
data of the year 1999 of the Environmental Research Center and Tartu
University (SO4 mg/m2) (figure 2.26).
According to the above mentioned convention and taking account of
EU Directive 88/609/EEC about limit values of emissions of pollutants
from large combustion equipment into ambient air, Ministry of the
Environment has compiled "State Programme for Reduction of Emissions
of Pollutants from Large Combustion Equipment into Ambient Air".
Table 2.10 shows emissions of SO2 and NOx from
large boiler houses with capacity 50 MW or above. Their percentage
of summary emission of SO2 and NOx is correspondingly
92% and 79%.
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Measures to be taken for the reduction of emissions of pollutants are given within the frames of the programme:
- technological measures, including reconstruction of equipment, implementation of new combustion technology (implementation of new combustion technology of oil shale, basing on circulating boiling layer, in energy block no. 8 of the Estonian Power Station) etc.;
- alteration of used fuel type, e.g. use of natural gas;
- use of fuel with low sulphur content.
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According to the regulation no. 15 of the Minister of Economy
"Quality requirements for liquid fuels" from June 2, 2000 it is allowed in Estonia to use heavy fuel oil with sulphur content 3.0% until January 1, 2003 and with sulphur content 1.0% after that term. Limit values of the emissions of sulphur dioxide and nitric oxides are directly regulated with regulation no. 60 of the Minister of the Environment
"Limit values of emissions of pollutants per volume unit of gases exiting from combustion
equipment" from October 26, 1998.
Figure
2.24. Emissions of SO2 from stationary pollution sources
in 1999 (tons per year).
Figure
2.25. Emissions of NOx from stationary pollution sources
in 1999 (tons per year).
Figure 2.26. Iso-lines of precipitated
sulphate (SO4 mg/m2) according to the data of Estonian
precipitation monitoring in 1999.
Table 2.10. Emissions of SO2
and NOx from large combustion equipment (th. t).
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