Distribution of the stable isotopes (δ

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

Specific of Stable Carbon Isotopes Determination in Organic-Bearing Sediments

Проведено исследование изотопного состава углерода в органосодержащих донных осадках термального озера Фумарольное (кальдера Узон, Камчатка). Представлены результаты изучения изменений δ13С в донных осадках термального озера при последовательном разложении H3PO4 в течение 2 ч, 24 ч и 7 дней. На примере двух образцов показано изменение δ13С во времени и после обработки HCl и H2O2. После обработки HCl значения δ13С изменяются относительно исходных от 1 до 3 ‰, что можно учесть при интерпретации данных. При стандартной процедуре удаления карбоната перекисью водорода выявляется существенная трансформация остаточного С‑содержащего вещества в случае длительной реакции с Н3РО4 при повышенных температурахThe study of the carbon isotopic composition in organic-bearing bottom sediments of the thermal lake Fumarolnoye (Uzon caldera, Kamchatka) has been carried out. The results of studying δ13C changes in the bottom sediments of a thermal lake during the sequential extraction of H3PO4 for 2 hours, 24 hours and 7 days are presented. The change in δ13С with time and after treatment with HCl and H2O2 is shown using two samples as an example. After treatment with HCl, the δ13С values change relative to the initial ones from 1 to 3 ‰, which can be taken into account when interpreting the data. The standard procedure for removing carbonate with hydrogen peroxide reveals a significant transformation of the residual C‑containing substance in the case of a prolonged reaction with H3PO4 at elevated temperature