Isotope Composition of Carbon and Nitrogen in Subterranean Karst Geosystems Components: The Case of Excursion Caves of Cis-Urals and the Caucasus

• Main Authors: S. M. Turchinskaia, A. A. Semikolennykh, S. E. Mazina, E. P. Zazovskaya, С. М. Турчинская, А. А. Семиколенных, С. Е. Мазина, Э. П. Зазовская
• Other Authors: The article is an output of an assignment theme of IGRAS no. FMGE-2019-0006 (processing and analysis of field material). The authors are sincerely grateful to Corresponding Member of the Russian Academy of Sciences A.V. Tiunov for his help in measurements and valuable recommendations at all stages of the study., Исследование выполнено в рамках темы Государственного задания ИГРАН № FMGE-2019-0006 (обработка и анализ полевого материала). Авторы выражают искреннюю благодарность чл.- корр. РАН А.В. Тиунову за помощь в проведении измерений и ценные советы на всех этапах исследования.
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: Izvestiya Rossiiskoi Akademii Nauk. Seriya Geograficheskaya 2023
• Subjects: стабильные изотопы углерода и азота; подземные карстовые геосистемы; карстовые пещеры; ламповая флора; фототрофные сообщества; органоминеральные взаимодействия; почвоподобные тела; солоиды; subterranean karst geosystems; karst caves; lampenflora; phototrophic communities; biomineral interactions; soil-like bodies; soloids; taiga
• Online Access: https://izvestia.igras.ru/jour/article/view/1653; https://doi.org/10.31857/S2587556622050132

The results of the isotopic composition studies (δ13С / δ15N) of phototrophic communities in the karst caves are presented. The caves were rangier by different physical-geographical regions: mountain taiga (Kungurskaya Ledyanaya cave) and mountain humid-subtropical forest (Akhshtyrskaya or Bolshaya Kazchebrodskaya cave and Novoafonskaya cave named after G.Sh. Smyr). The fractionation of carbon and nitrogen stable isotopes were studied in the communities of phototrophic organisms of subterranean landscapes (lampenflora), as well as the influencing of one’s to the soil-like bodies (soloids) under these communities. That is discussed the difference of lampenflora phytomass isotopic composition in compare with terrestrial similar systematic and ecological groups of phototrophs towards enrichment with isotopes 12C and 14N. An increase of interests of light carbon and nitrogen isotopes was also noted for cave soloids in comparison with soils on the day surface. The ratio of carbon stable isotopes varies from –47.3 to –32.4‰ for subterranean ecosystems and from –35.5 to –26.8‰ for control samples (daylight surface). The isotopic composition of nitrogen shows a smaller variation from –8 to –1.8‰—in underground habitats, and from –3.5 to +2.0‰—on the surface. The hypothesis regarding the specifics of gas exchange in subterranean space and biological circulation of carbon dioxide in a semi-closed atmosphere was created. This hypothesis is confirmed by the trend of accumulation of the 12C isotope in lampenflora and soloids with distance from the cave entrance, which is due to the reduction of air circulation. The data of carbon and nitrogen isotope composition for the lampenflora and soloids from karst caves in the different physico-geographical zone are also generalized and systematized in this work, there is a geographical trend, but it is necessary to increase the number of studied objects from different natural zones to confirm this conclusion. Обобщены результаты исследований изотопного состава (δ13С и δ15N) ...