Molecular Indicators of Sources and Biodegradation of Organic Matter in Sediments of Fluid Discharge Zones of Lake Baikal
Inna Morgunova,
Petr Semenov,
Anna Kursheva,
Ivan Litvinenko,
Sergey Malyshev,
Sergey Bukin,
Oleg Khlystov,
Olga Pavlova,
Tamara Zemskaya,
Alexey A. Krylov
Affiliations
Inna Morgunova
Federal State Budgetary Institution “Academician I.S. Gramberg All-Russian Scientific Research Institute for Geology and Mineral Resources of the Ocean” (FSBI “VNIIOkeangeologia”), 190121 St. Petersburg, Russia
Petr Semenov
Federal State Budgetary Institution “Academician I.S. Gramberg All-Russian Scientific Research Institute for Geology and Mineral Resources of the Ocean” (FSBI “VNIIOkeangeologia”), 190121 St. Petersburg, Russia
Anna Kursheva
Federal State Budgetary Institution “Academician I.S. Gramberg All-Russian Scientific Research Institute for Geology and Mineral Resources of the Ocean” (FSBI “VNIIOkeangeologia”), 190121 St. Petersburg, Russia
Ivan Litvinenko
Federal State Budgetary Institution “Academician I.S. Gramberg All-Russian Scientific Research Institute for Geology and Mineral Resources of the Ocean” (FSBI “VNIIOkeangeologia”), 190121 St. Petersburg, Russia
Sergey Malyshev
Federal State Budgetary Institution “Academician I.S. Gramberg All-Russian Scientific Research Institute for Geology and Mineral Resources of the Ocean” (FSBI “VNIIOkeangeologia”), 190121 St. Petersburg, Russia
Sergey Bukin
Limnological Institute, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk, Russia
Oleg Khlystov
Limnological Institute, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk, Russia
Olga Pavlova
Limnological Institute, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk, Russia
Tamara Zemskaya
Limnological Institute, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk, Russia
Alexey A. Krylov
Federal State Budgetary Institution “Academician I.S. Gramberg All-Russian Scientific Research Institute for Geology and Mineral Resources of the Ocean” (FSBI “VNIIOkeangeologia”), 190121 St. Petersburg, Russia
This paper performs a detailed study of a wide set of organic-geochemical proxies in 15 sediment cores collected from the main basins of Lake Baikal (the northern, the central and the southern) where processes of focused fluid discharge were detected. A variety of studied zones includes sites with gas and hydrothermal seepage, mud volcanoes with or without gas-oil fluid discharge, gas hydrates and authigenic carbonates. The composition of the dispersed organic matter and individual hydrocarbon molecular markers (n-alkanes, dimethyl alkanes, isoprenoids, steranes, terpanes and polycyclic aromatic hydrocarbons) testify to the input from predominantly allochthonous terrestrial and autochthonous microbial and algal sources. The studied sources, maturity and biodegradation parameters of organic matter vary significantly for areas with different fluid discharge. The composition of specific biomarkers including isoprenoids and immature hopanoids reflects the lateral and vertical changes of microbial activity in sediments associated with various environmental conditions. The identified types of terpanes distribution (mature, mixed and immature) correlate well with types of fluid discharge and attest to the development of various methanogenic and methanotrophic microbial communities in sediments. Moreover, the revealed specificity of microbial molecular markers distribution allowed us to suggest the fluid discharge processes in zones where they were not previously detected.
