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

 8.1. 
 Water resources and their use 
Water is a renewable natural resource and a pre-requisite for life 
on the Earth, and it is the most important food product for humans 
and many other species. Fresh water is only a small part of the 
terrestrial water – about 3%. Much of the fresh water (a little more 
than two-thirds) comes from glaciers and snow, while one-third – is 
the underground water, because rivers and lakes make up only a 
very small part of the fresh water.
The  formation  of  natural  water  sources  is  influenced  by  the 
hydrological cycle, which can be divided into five major parts: the 
waters of the oceans, atmo sphere, glaciers, underground, and fresh 
water resources. Hydrological cycle shows the interrelation among 
Synthetic detergents 
contain a variety of sub‑
stances that may pollute 
the aquatic environment:
1. surfactants such as 
sodium dodecyl 
sulfate;
2. bleaching agents – 
usually various 
oxidizing agents such 
as sodium perborate;
3. enzymes such as lipase;
4. corrosion inhibitors 
such as sodium silicate;
5. fragrances; 
6. inert material (fillers) 
such as sodium sulfate;
7. stabilizers, such as 
magnesium silicate.
Surfactants are a group 
of water‑soluble organic 
substances that concen‑
trate on the surfaces and 
reduce the water surface 
tension. 

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8. WATER POLLUTION
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these  key  water  sources  and  reflects  the  great  role  of  evaporation 
and precipitation fall processes in formation of the water balance. 
The major energy factor which determines the participation of water 
in the global water cycle is the solar radiation causing the mass of 
water on the Earth surface to heat up and evaporate. Water does 
not evaporate solely from the surface of the seas and oceans, – the 
soil moisture, glaciers and the snow cover of the Earth evaporate, 
too. Water circulation time for different elements of the hydrological 
cycle is different: for atmo spheric water it is 10 days, 12 days for 
the  water  in  rivers,  in  lakes  –  7  years,  the  active  exchange  zones 
of underground water (groundwater) – 200-300 years, the water in 
the oceans – 3000 years, artesian groundwater – 5000 years, water 
hidden in continental glaciers – 8000 years. These parameters allow 
to estimate, how much water participates in a overall cycle per 
year – these are only 0.03% of the total amount of water, but all the 
water on the Earth makes a complete cycle only in about 3000 years.
Although the fresh water supply is significant, not all the surface 
and underground water can be used for human economic activities. 
Regarding the number of global population from the perspective 
of  separate  continents,  these  values  can  be  reflected  as  available 
freshwater amounts per capita (Table 8.1).