Distribution of the stable isotopes (δ¹⁸O, δd Ee Cyrillic sign δ¹³C) in natural waters of the Baydar valley (Crimean Peninsula)

Results of the study of the stable isotopes (δ¹⁸O, δD and δ¹³C) distribution in natural waters of the Baydar valley (southwestern part of the Crimean Peninsula) are presented. The study region holds fresh and ultra-fresh waters of predominantly bicarbonate calcium composition with TDS varying from 194 to 1137 mg/dm³. The research results revealed that all of the studied waters are of atmospheric origin that lie either along the global (GMWL) or local (LMWL) meteoric water lines. The established variations are: from -9.5 to -5.6‰ for δ¹⁸O values in waters with δD values varying from -64.0 to -40.0‰. The source for bicarbonate ion enriched in δ¹³C in natural waters of the Bauydar valley are carbonate sedimentary rocks, atmospheric carbon dioxide and organic compounds. Surface waters have heavier isotopic composition δ¹³C (-9.2 - -7.0‰) because of the atmospheric CO₂. Artesian waters are differentiated by lighter δ¹³C (-12.8 - -10.7‰) due to the interactions between carbonate rocks and the dispersed organic matter. Water sources (springs, wells) are characterized by the widest variations of δ¹³C (-6.9 - -15.5‰) due to the presence of the atmospheric CO₂ and intense processes of biochemical decomposition of organic compounds in the soil layer.