Gas Distribution Features in the Upper Layer of Marine Sediments in the Continental Shelf of the Laptev Sea–Arctic Ocean Profile

• Published in: Oceanology (Washington. 1965) 2021-07, Vol.61 (4), p.472-487
• Main Authors: Sevastyanov, V. S., Fedulova, V. Yu, Stennikov, A. V., Kuznetsova, O. V., Naimushin, S. G., Dushenko, N. V., Krivenko, A. P.
• Format: Article
• Language: English
• Subjects: Biological activity; Carbon; Carbon dioxide; Chemical composition; Continental shelves; Depth; Dimethyl sulfide; Distribution; Earth and Environmental Science; Earth Sciences; Gases; Hydrocarbons; Hydrogen sulfide; Isotopes; Marine biology; Marine Chemistry; Marine sediments; Methane; Ocean floor; Oceanography; Sediment; Sediments; Sulphides; Vertical profiles
• ISSN: 0001-4370; 1531-8508
• DOI: 10.1134/S0001437021030140

Hydrocarbon gases (CH 4, C 2 H 4 , C 2 H 6 , C 3 H 6 , C 3 H 8 , C 4 H 8 , n -C 4 H 10 , i C 4 H 10 , n C 5 H 12 , i C 5 H 12 , neo -C 5 H 12 ), CO 2 , H 2 S, CH 3 SCH 3 , and COS were obtained from various marine sediment horizons at a depth of up to 45 cm on the continental shelf, the slope of the Laptev Sea, and Arctic Ocean floor. Their concentrations were measured, gas concentration distribution curves were plotted as a function of distance from the seafloor sediment surface, and the carbon isotopic composition of CO 2 was determined. It is shown that the hydrocarbon (HC) gas content depends on biological activity in marine sediments. The general pattern of the concentration distribution was revealed: the HC gas concentration increased in the region of increased dimethyl sulfide concentration, while the COS concentration decreased. The isotopic composition of CH 4 carbon in the seep area in the vertical profile of column 5953-3 varied from –80‰ on the surface of the marine sediments and increased to –58‰ at a depth of 22 cm. The carbon isotopic composition of CO 2 also increased with sediment depth, reaching –15.9‰.