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

Figure 4.3. 
Variability of 
the Earth’s atmosphere 
and temperature 
depending on the 
distance from the Earth’s 
surface

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48 
ENVIRONMENT, POLLUTION, DEVELOPMENT:  THE CASE OF UZBEKISTAN
photochemical reactions in the stratosphere – first of all, the formation 
and disintegration of ozone molecules, and also the intensive sorption 
of ultraviolet light.
The concentration of gases that form the upper layers of the 
atmo sphere is considerably lower. These gases are in an ionised 
state, and they are subject to the influence of high-energy electro-
magnetic radiation coming from the Sun and outer space. Therefore, 
molecules  move  at  much  higher  speeds  in  the  rarefied  air  of  the 
upper atmo sphere. Reactions taking place in these parts of the atmo-
sphere are rather different from those near the Earth’s surface.
The hydrosphere is the whole of all water on the Earth’s surface 
and in the Earth’s crust near the surface. The World Ocean comprises 
the largest part of it. The cycling of substances is mostly associated 
with the Earth’s hydrological cycle. The presence of water is a 
precondition for life on the Earth, and the existing forms of living 
organisms are to a great extent determined by water. Moreover, 
water is the main substance forming living organisms. Water is not 
only  the  main  component  of  the  hydrosphere;  it  also  significantly 
affects  the  processes  in  the  biosphere,  atmo sphere  and  –  being  a 
critical factor for many geological processes – the litho sphere. The 
role of water in the environ ment is decisive not only due to its total 
volume on the Earth but also due to its substantial properties.
The  mass  of  the  hydrosphere  is  1.5 × 10
18 
tons, and its total 
area (ocean + glaciers and ice caps + lakes + rivers + swamps + 
wetlands) is 383 million square kilometres, which is 75% of the total 
area of the Earth’s surface (510 million square kilometres). 
Asthenosphere
Transition zone or 
the middle layer of the mantle
Lower mantle
Transition or ‘D’ layer
Outer core
Inner core
Continental crust 
(20–60 km)
Seawater 
(0–5 km)
Oceanic crust
(5 km)
Upper mantle
400 km
670 km
2900 km
5100 km
6378 km
Lithosphere 
(50–200km)
Figure 4.4. 
Inner 
structure of the Earth

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4. HUMANS AND THE ENVIRONMENT
 49
The hard and rigid outer layer of the Earth – the litho sphere – 
is  up  to  200 km  deep,  and  it  comprises  the  Earth’s  crust  and  the 
outer part of the upper mantle. The litho sphere is underlain by 
the astheno sphere and the deeper part of the upper mantle made 
of magma that can come to the Earth’s surface during volcanic 
eruptions. The Earth’s outer core is liquid, and it makes up ~30% 
of the Earth’s mass, whereas the inner core is solid and composed 
mostly of iron and nickel (Figure 4.4).