Хабарлар ы series of geology and technical sciences

9
ISSN 2224-5278
Series of Geology and Technical Sciences 1. 2022
11
Sauskan
43
0 
49' 52
0 
51'
Q, sands
494
-7.8 -68.1 ˂ 6 7.94
12
Tuesu
43
0 
22' 53
0 
24' K, sands, sandstones
1008
-7.6 -66.9 ˂ 7 7.94
13
Shagala sanatorium
43
0 
37' 51
0 
11' K, sands, sandstones
8325
-5.5
-54
7.79
14
Beineu
45
0 
17' 55
0 
31'
Q, sands
-11.1 -92.5
-
15
Sam
45
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14' 55
0 
52'
Q, sands
395
-9.5 -80.6 ˂ 7 7.38
Figure 2. Isotopic composition of groundwater in the Mangystau region.
a - groundwater, b - global meteoric water line
Tritium
is an ideal tracer to study water circulation in the zone of active water exchange [25, 26]. Natural 
concentrations of cosmogenic tritium in atmospheric precipitation are estimated to be about 1-5 TU (0.12-
0.6 Bq/L), and during fusion charge testing in 1952-1964 its maximum concentrations in atmospheric 
precipitation reached 10
4
TU. Given the half-life of tritium T
1/2
= 12.26 years, we can assume that the tritium 
that entered the groundwater in the pre-nuclear era to the present time has decayed completely, it allows us to 
easily diagnose the contribution of modern waters in the structure of groundwater resources.
Concentrations of 
deuterium and oxygen-18
in natural waters experience the most signifi cant, in 
comparison with other substances, changes in isotopic composition due to fractionation during evaporation, 
condensation, and freezing [27-29]. The regularity is strictly observed – the heavy isotope accumulates in the 
more condensed phase. It should be emphasized that fractionation usually does not occur during water melting 
due to too low diffusion rates of water molecules in ice. The isotopic composition of water is expressed in 
relative units, using the Vienna standard of average ocean water as a reference:
δХ = (Rsample/Rst — 1) × 1000, ‰
where R = 
2
Н/
1
H or 
18
O/
16
O – atomic ratio of hydrogen and oxygen isotopes in the sample and the standard 
(indices sample and st, respectively).
For the analysis of natural groundwater formation conditions, the results of measurements were plotted 
on the δ
18
O ÷ δ
2
H diagram, which refl ects the regular distribution of isotopic composition of atmospheric 
precipitation, the so-called global meteoric water line (Figure 2). Global line of meteoric waters is a relation 
between mean annual air temperature and mean annual precipitation isotopic composition according to 
different meteorological stations of the Earth – from tropical latitudes to Greenland and Antarctica.
The fractionation of the isotopic composition of water, which takes place during phase transformations, is 
also shown in relation to the global line of meteoric waters. In this case, the rule is strictly observed – during 
evaporation, the isotopic composition of water changes in accordance with the evaporation line, where the 
residual water is isotopically weighted, and the evaporated steam is lightened. In the process of freezing, the 
forming ice is isotopically weighted and the residual water is lightened.
The content of stable isotopes in water samples of Mangystau region changes in the following limits: from 
-14,5‰ to -5,5‰ for 
18
O; from -107,0‰ to -54,0‰ for 
2
H. 
Tritium radionuclide 
3
H was measured on liquid scintillation beta spectrometer TRI-CARB 2900TR 
produced by Hewlett Packard company and designed for determination of specifi c activity of 
3
H. 
According to the results of β-spectrometric analysis it was established that in the analyzed samples the 
concentration of man-made radionuclide is less than the detection limit of ˂ 7 Bq/L in water. In the 50s and 

10
N E W S of the Academy of Sciences of the Republic of Kazakhstan
early 60s, large amounts of tritium were released into the atmosphere as a result of atomic bomb testing. Thus, 
the sediments were labeled [6, 30], and if the groundwater sample does not contain significant amounts of 
tritium, it definitely indicates that the water has not been fed for the last two or three decades.

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