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

Table 8.5. 
Elements required for plant development and their sources in 
waters 
Element
Source of elements
Function
Macro-elements:
carbon (CO
2
) 
atmosphere, living organisms forms biomass 
hydrogen 
water 
forms biomass 
oxygen 
water, air
forms biomass 
nitrogen 
atmosphere, living organisms protein 
phosphorus 
mineral weathering,  
living organisms 
DNA, RNA, ATP 
metabolism
potassium 
mineral weathering
protein
sulfur 
mineral weathering, sulfates 
 metabolism
calcium
mineral weathering
metabolism
Microelements:
B, Cl, Co, Cu, Fe, Mo,
Mn, F, V, Zn
Mineral weathering
metabolic functions
Generally, the eutrophication is a natural process and it is 
considered to be one of the basic stages in the development process 
of water body (Figure 8.7) – from the oligotrophic state, as the life 
processes develop and biogenic elements are supplied from the 
catchment  area,  entering  into  eutrophic,  and  finally  to  become 
overgrown.  At  the  same  time,  anthropogenic  water  pollution 
can  significantly  speed  up  this  process  and  lead  to  anthropogenic 
eutrophication. Eutrophic waters are characterized by high biogenic 
element concentrations in water and sediment (water phosphorus 
content  >20  µg/l),  high  content  of  organic  substances  in  the 
water, high biological productivity of water, muddy water, oxygen 
deficiency in the demersal zone and typically anoxic environ ment 
under the ice in the winter period, the loss of biodiversity while the 
total mass of living organisms in the waters increase. Oligotrophic 
waters are clear waters with low organic substance content, low 
biological productivity, high oxygen content in the water, high 
biodiversity in the waters, but a low total mass of living organisms.
«Eutrophic» is a deriva‑
tive of the Greek origin 
meaning «well fed.» 
This name represents 
the conditions in the 
water body due to the 
increase of biogenic 
elements, when the 
biological processes are 
greatly intensified. It is 
first observed as growth 
of algae, accumulation 
of organic matter, and 
eventually leads to a 
significant deterioration 
of water quality. 

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