Materials and methods. Fifteen groundwater samples from wells in the Mangystau region were collected
for studies (Fig.1). For isotopic analysis, samples were taken only from self-discharging wells, and wells
operated by submersible pumps. This somewhat narrowed the range of observed water points, but also sharply
reduced the possibility of accidental influence of anthropogenic, seasonal, and other factors on the sampling
results [24].
The results of the isotope analysis are presented in Table 1. Stable isotope ratios of
2
H/
1
H and
18
O/
16
O in
the measured sample were measured on a high-sensitivity laser spectrometer LGR 912-0008. Water samples
calibrated against the International Standard VSMOW (IAEA) were used as internal standards. The accuracy
of
2
H and
18
O measurements was ± 1 ‰ and 0.5 ‰, respectively.
Table 1. Measured values of indicators of chemical and isotopic composition of groundwater
