ESTIMATION OF METHANE FLOW FROM THE BOTTOM OF THE KARA SEA

Abstract

During the expedition on the R/V “Akademik Mstislav Keldysh” (81st cruise) in 2020, extensive material was selected, representing columns of bottom sediments up to 6 meters deep in the Kara Sea. After lithological description of the columns, sediment samples were taken from different horizons for degassing of pore gases. The extracted gas samples were analyzed for the content of the main gases – methane (CH4), carbon dioxide (CO2) and light hydrocarbons. The characteristic features of CH4 and CO2 content changes with depth of bottom sediment at station 6879 (Kara Sea shelf) were studied. A model of gas diffusion was constructed taking into account the biochemical reactions of methanogenesis and methane oxidation. The rate of methane formation can be estimated by the value J ≈ 3 × 10–10 μg sec–1 L–1 (per liter of sediment). The rate coefficient of methane consumption by microorganisms is K ≈ 0.5 × 10–10 sec–1. The methane flux from the bottom surface of the Kara Sea near station 6879 is q ≈ 3.47 × 10–2 μL m–1 year–1.