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

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Table 8.4. 
Groups of major water pollutants 
Inorganic salts 
Pesticides 
Persistent organic compounds (e.g., polychlorinated biphenyls) 
Radionuclides 
Oil and its derivatives (such as diesel fuel) 
Biogenic elements (e.g., nitrate ions, phosphate ions) 
Surfactants 
Metal compounds 
Gases 
Toxic inorganic substances (such as cyanide ions) 
The heat (thermal pollution) 
Pathogenic microorganisms
A  significant  source  of  water  pollution  is  the  use  of  chemical 
fertilizers in agriculture (Figure 8.5). 
0
20
40
60
80
100
120
140
1963
1968
1973
1978
1983
1988
1993
1998
Co
nsumption, kg/ha
Industrially developed countries
Development countries
In Uzbekistan pollution of water with biogenic and organic 
substances  is  significant  and  widespread,  while  other  types  and 
elements of pollution are characteristic only of the local point 
pollution sources.
The  term  «biogenic  elements»  denotes  the  nutrients  of  living 
aquatic  organisms  –  nitrogen  compounds  (inorganic  ions  NH
4
+
, 
NO
2
–
, NO
3
–
 and organic nitrogen compounds), phosphorus com-
pounds (inorganic PO
4
3–
, HPO
4
2–
, H
2
PO
4
–
, polyphosphate ions and 
orga nic compounds) as well as iron and silicon compounds in their 
different oxidation levels and forms, taking into account their great 
importance in ensuring aquatic life processes.