Māris kļaviņŠ, azamat azizov, JĀnis zaļoksnis environment, pollution, development: the case of uzbekistan

Figure 7.11. 
Sulfur 
dioxide emissions from 
mobile and stationary 
sources in Uzbekistan
Figure 7.12. 
Sulfur 
dioxide and nitrogen 
oxide emission 
amount variability in 
Latvia, 1990–2001 and 
emissions forecast until 
2020.

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128 
ENVIRONMENT, POLLUTION, DEVELOPMENT:  THE CASE OF UZBEKISTAN
The average lifetime of SO
2 
in the atmo sphere is 5 days and it is 
accelerated by the presence of nitric oxides, aerosols, hydrocarbons 
(Figure 7.13). 
As  the  substances  of  alkaline  character  –  metal  oxides, 
carbonates, ammonium ions, ammonia – are also released into the 
atmo sphere, the reactions take place which result in formation of a 
corresponding metal or ammonium salts. In addition, the oxidation 
of SO
2
 in the tropo sphere takes place also in a liquid phase, that 
is, SO
2
 dissolves in water – water drops; i.e., rather than SO
2, 
in the 
oxidation process participates sulphurous acid H
2
SO
3 
or hydrogen 
sulfites
 
HSO
3
. Particularly stable aerosols are formed, if the oxidation 
processes take place in the liquid phase, SO
2
 and their oxidation 
product transformations are interrelated.
The compounds formed by oxidation of sulfur dioxide fall 
both in form of rain and snow (wet deposition), as well as dust 
(dry  deposition).  An  important  part  of  the  sulfate-ion  containing 
substances falls particularly in the form of dust particles.
Since 1990, the annual total sulfur dioxide emissions in Latvia 
have fallen significantly. If at the beginning of the 1990s it was due 
to the slowdown in the economy, then as of 1996, in the years of 
economic upturn, an important contribution to the reduction of 
air pollutant emissions was brought by application of new environ-
mental laws and regulations providing for implementation of 
measures to minimize air pollution and improve air quality. 
The main sources of sulfur dioxide emissions are the energy 
industry,  namely,  the  production  of  energy  by  burning  different 
fuels. The intensity of contamination greatly depends both on the 
process of combustion, as well as on the fuel quality. As a result of 
coal combustion, about 70% of the total anthropogenic emission 
amount is released into the atmo sphere. The sulfur compound 
content of coal is between 1.0% and 4%. In oil sulfur content is 
between 0.3% and 3%. In industry sulfur dioxide is produced by 
burning of sulfur, hydrogen sulfide, as well as by burning of metal 
sulfides. Again, these processes are sources of SO
2
 emission.
Sulfur dioxide is released into the atmo sphere also in the coal 
and  oil  refinement  process,  in  the  production  of  sulfuric  acid,  by 
burning household waste. In Latvia the main source of sulfur dioxide 
is the so-called stationary sources of emissions – energy facilities. Of 
the most important environ mental pollutants, SO
2
 emissions are the 
largest.
Fuels, primarily burning fossil fuels, are considered to be a 
source of the major formation process of several environ mental 
pollutants (Figure 7.14). In the burning process of fossil fuels the 
formation of sulfur compounds takes place, and the reaction 
between  the  air-forming  gases  –  nitrogen  and  oxygen  –  in  high 
SO
2
H
2
O
2
H
2
O
2
H
2
SO
4
O
3
OH
’
O
2
HSO
3
–
SO
3
SO
2