Хабарлар ы series of geology and technical sciences
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1.6-13
Диссертация Надеина
| Results and discussion
. Figure 2 clearly shows that the isotopic composition of groundwater of Mangystau region is enriched by the heavy isotope δ 18 O relative to the generally accepted meteoric water line. This is probably caused by evaporation concentration, during which the light isotope δ 16 O is removed from water, thus enriching water with heavier isotope δ 18 O. The exception is the samples taken from two wells of Kuiylys, which have relatively identical “light” isotope composition and are not subject to changes caused by hydrogeological processes (evaporation processes and weak water exchange). This may be due to the fact that these waters lie relatively deeper and are localized in an impermeable aquifer, which excludes ingress of surface water and atmospheric precipitation. Detection of light by composition groundwater (Kuiylys) δ 2 H < -107 and δ 18 O < -14 ‰, suggests that these groundwaters were formed in cold climatic conditions, with average annual temperature below 0° C [6]. In all other cases, groundwater is subject to change in isotopic composition. The samples taken from the wells Sad-Dubskogo (thermo-mineral waters) and Saubet have a characteristic relationship, indicating one source of formation and hydro-geological relationship. The opposite picture is observed on the samples of Zhyngyldy, Ulanak and Moinak. Despite the fact that Zhyngyldy, Ulanak and Moinak are located next to each other by coordinates, the waters from these points have a completely different isotopic composition. The isotopic ratios indicate that the waters are taken from different aquifers without any correlation. Also, the water from the village of Sam has no correlation in isotopic composition with the waters of Beineu, which is located nearby. According to the comparative isotopic analysis, the waters of Sam are strongly subject to the process of evaporation compared to the waters of Beineu, which indicates different aquifers. Conclusion. Waters sampled from the Shagala Sanatorium (Aktau) are characterized by the “heaviest” isotopes, perhaps these waters are subjected to an intense process of evaporative concentration. Isotopic researches of underground fresh and low-saline waters spread in Mangystau region have allowed to draw the following conclusions: 1. Ratios of stable isotopes δ 18 O and δ 2 H in groundwater of the region show a single atmogenic origin. 2. Tritium concentrations were measured in order to establish the rate of water exchange in the fields. For the groundwater of the study area, tritium concentrations are less than the detection limit ˂7 Bq/l in water, indicating difficult water exchange and lack of connection with surface water. In conclusion, we note that for reliable determination of stable isotope ratios, seasonal sampling of groundwater from the same sites throughout the year is necessary. The same should be used data on the isotopic composition of atmospheric precipitation of Mangystau region. Global lines of meteoric waters are obtained by interpolation cannot be considered reliable for the Mangystau region, as the nearest network stations GNIP (Global Network on Isotopes in Precipitation) are at a considerable distance and near the Caspian Sea, which affects the precipitation. This research has been funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. BR10965134). жүктеу/скачать 0,67 Mb. Достарыңызбен бөлісу:
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