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

Table 4.1. 
Main structural elements of the Earth
Chemical elements
Aggregative state
Atmosphere
N
2
, O
2
, H
2
O, CO
2
, Ar
Gaseous
Hydrosphere
H
2
O (water, ice), substances dissolved 
in water (Na
+
, Ca
+2
, Cl
–
)
Liquid, solid
Biosphere
Organic substances, H
2
O
Liquid, solid
Lithosphere
Crust
Silicates, carbonates, sulphides, oxides Solid
Mantle
Silicates (olivine, pyroxene)
Solid
Core
Iron and nickel
Fluid (inner core – solid)
Table 4.2. 
Mass of the Earth’s main components and the turnover period of 
substances in them
Mass, kg
Turnover period, years
Biosphere
4.2 × 10
15
60
Atmosphere
5.2 × 10
18
0.2
Hydrosphere
1.4 × 10
21
1600
Crust
2.4 × 10
22
> 3 × 10
7
Mantle
4.0 × 10
24
> 10
8
Core
1.9 × 10
24
Permanent 
A  typical  example  of  negative  feedback  in  an  inanimate, 
technical system is Watt’s Regulator (Figure 4.2). When the fly-ball 
rod rotation speed increases, the centrifugal force makes the system 
close the steam valve to the cylinder, thus ensuring that the engine 
always runs at the same speed. 
Another factor that significantly influences the processes taking 
place on the Earth is the global sum of all living organisms – the 
bio sphere. Life originated about 1.6 billion years after the formation 
of the Earth, and since then it has been substantially influencing the 
develop ment of our planet. A great number of species of organisms 
have developed, flourished and disappeared since the times of the 
origination of life. Human beings have evolved during a very short 

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4. HUMANS AND THE ENVIRONMENT
 45
period of the Earth’s development process, and it is understandable 
that from the human perspective it appears as the most significant 
period. Hence, an understanding of how we can affect the environ-
ment around us is also significant. Nowadays human activities can 
influence the processes taking place on the Earth. Life affects the 
Earth’s combined mass of water – the hydrosphere – tropo sphere and 
the upper layer of the Earth’s crust.
Steam valve
Steam feed
Steam engine
Centrifugal
mechanism
Each  scientific  discipline  has  its  specific  object  of  study.  Inas-
much as the object of environ mental science is complex environ-
mental systems, it can be defined as a science studying the systems 
of the Earth, their interactions and the influence of human beings on 
them.