ISOTOPIC COMPOSITION (δ18O, δD, δ13C, δ34S) OF GROUNDWATERS IN THE AREA OF TOREY LAKES (EASTERN TRANSBAIKAL REGION)

The relevance of the work is associated with the problem of fresh water resources shortage in arid regions, the solution of which is impossible without understanding the conditions and mechanisms of water's chemical composition formation in the natural environment. The aim of the research is to supplement information on the origin and conditions of groundwater's formation using the basis of new data on water's stable isotopes (delta O-18, delta D) and dissolved carbon and sulfur (delta C-13, delta S-34). Study objects are groundwaters of the upper dynamic zone of the Torey Lakes (eastern Transbaikal region) - springs, boreholes and wells depth (no more than 70 m), partly rivers' and lake's waters. Methods. Isotopic studies of water and dissolved C and S were carried out using an isotope mass spectrometer Finnigan-MAT 252 (Germany) at the FEGI FEB RAS Analytical Centre; water's chemical composition - using modern standard methods: potentiometric titration, atomic absorption, flame emission, potentiometric method, titration method at the INREC SB RAS. Results. New data on the isotopic composition (H and O) of groundwater in the upper dynamic zone of the Torey Lakes area, as well as dissolved C and S are presented. Altitudinal zonality is noted in isotope's distribution The conclusions related to the origin and formation conditions were presented based on the results obtained, as well as the data on partially lake's and meteoric waters: water of infiltration with little influence of evaporation processes (mixing with lake waters). A fairly uniform isotopic composition of groundwater was noted, despite the differences in chemical composition. No relationships were found between isotopic composition and salinity, basic ions and pH within groundwater, however, the general evolution of the composition in the direction of "atmospheric-groundwaters-lake waters" is characterized, in addition to the increase in salinity and pH, by enrichment in isotopes O-18, H-2, C-13.