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

Figure 4.23. 
Nitrogen 
biogeochemical cycle 
Flows stated in PgC/year.

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4. HUMANS AND THE ENVIRONMENT
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1900
1920
  1940    
1960
1980
2000
2050
300
250
200
150
100
50
0
Natural N
fixation
amount 
Total
Fertilisers
Agricultural N fixation
Year
Tg N/yea
r
Projected N
fixation
amount
Fossil fuel combustion
Nitrogen compounds are among the basic nutrients needed for 
plant growth, and they are used in agriculture for soil fertilisation 
in order to promote the growth and yield capacity of cultivable 
plants. Unfortunately, a significant part of the nitrogen compounds 
used for fertilisation leaches into surface waters and groundwaters 
and, along with surface runoff – further into the seas and oceans. 
Nitrogen compounds also fall out with atmo spheric precipitation 
(Figure 4.25). In effect, both water and soil become oversaturated, 
causing eutrophication.
1860
1990
2050
  5 
25 
50  100  250  500  750  1000  2000  5000
In present-day Europe, the emission of nitrogen compounds has 
become one of the most hazardous environ mental pollution factors. 
It is an urgent problem for the Baltic Sea Region countries, where 
the concentration of nitrogen compounds initiates many harmful 
processes, including the pollution in the Baltic Sea. Thus, the issues 
related to the flow of nitrogen compounds, their utilisation amounts 
and emission reduction become burning issues on the agenda.