Isotopic and Geochemical Study of Organic Matter in Marine Sediments from the Indigirka Delta to the Ice Shelf Border of the East-Siberian Sea

Various hydrocarbon gases (СН 4, С 2 Н 4 , С 2 Н 6 , С 3 Н 6 , С 3 Н 8 , С 4 Н 8 , n -С 4 Н 10 ) and CO 2 have been extracted in low concentrations from different layers of marine sediments up to 2 m thick on the continental shelf of the East Siberian Sea along the profile from the mouth of the Indi...

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Bibliographic Details
Published in:Geochemistry international 2019-05, Vol.57 (5), p.489-498
Main Authors: Sevastyanov, V. S., Fedulov, V. S., Fedulova, V. Yu, Kuznetsova, O. V., Dushenko, N. V., Naimushin, S. G., Stennikov, A. V., Krivenko, A. P.
Format: Article
Language:English
Subjects:
Area
Carbon dioxide
Composition
Continental shelves
Diagenesis
Earth and Environmental Science
Earth Sciences
Freshwater
Freshwater ice
Gases
Geochemistry
Ice shelves
Inland water environment
Isotopes
Land ice
Low concentrations
Marine sediments
Maturation
Organic matter
Reduction
Rivers
Sediment
Sediment samples
Sediments
Sulfate reduction
Sulfates
Sulphate reduction
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Summary:Various hydrocarbon gases (СН 4, С 2 Н 4 , С 2 Н 6 , С 3 Н 6 , С 3 Н 8 , С 4 Н 8 , n -С 4 Н 10 ) and CO 2 have been extracted in low concentrations from different layers of marine sediments up to 2 m thick on the continental shelf of the East Siberian Sea along the profile from the mouth of the Indigirka River to the ice shelf border. A freshwater complex supplied by the Indigirka and other rivers has the dominant influence on the composition of organic matter (OM) in the almost entire studied area of the East Siberian Sea. Concentrations of most common gases CH 4 and CO 2 increase with increasing sampling depth in sediment core collected at station 5602-2, while the carbon isotopic composition of CO 2 decreases, reaching a value of –24‰. A sulfate reduction area was found at sediment depth of 48–70 cm. It was shown for the first time that the diagenesis of OM results in a systematic change in isotope fractional characteristics (IFC). IFC was obtained for the low-maturation OM, for OM from the sulfate reduction area, and for the high-maturation OM. OM in the low horizons of the sediment (below 77 cm from the surface) is much more evolved compared with the immature sediments of the upper horizons.
ISSN:0016-7029
1556-1968
DOI:10.1134/S0016702919050100