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Relationship between Methane Content in Siberian Permafrost and Soil Propertiesтезисы доклада
- Авторы: Brouchkov A., Fukuda M.
- Сборник: American Geophysical Union (AGU) 2004 Fall Meeting
- Серия: Eos, Transactions American Geophysical Union
- Том: 85
- Тезисы
- Год издания: 2004
- Место издания: [Washington], United States
- Номер статьи: C43A-12
- Аннотация: Methane is one of the greenhouse gases among other gases, and it is important to identify sources of methane. Permafrost deposits in Siberia contain large amounts of methane in air bubbles, and there is a high possibility of permafrost thawing due to climatic warming. However, distribution of methane in frozen deposits is still poorly known. It should be related to soil content and properties. Therefore, present knowledge of permafrost soils collected by a number of studies can be a key to understanding of methane distribution; the subject was never discussed before. Air bubbles from frozen soil and ice were sampled at the uppermost layers of permafrost from the depth up to 5 and more m in Eastern Siberia. The major study site was located in valley of Lena River. The permafrost samples were obtained by shallow borehole drilling. Soil composition, density and water content were also measured as well as the concentration of gases in the air bubbles. Total number of air samples was about 200. Air from soils was analyzed by gas chromatograph. No certain relationship between methane concentration and depth was found. Highly concentrated methane occurs in permafrost at different depths. Ice wedges contain less methane than frozen soils in general. There no obvious tendencies between water contents and values of concentrations of both methane and carbon dioxide were found. Methane content increases in general with water content increase, and carbon dioxide content becomes lower; however, in some cases the tendency is opposite, if the concentration is high (up to 70 ppt). Data collected on ion (salt) content is limited, but methane content rises with salinization increase. Low methane content and low salinization in the same time could be connected to possible thawing of permafrost when soil could be washed. Frozen soils containing large amounts of methane and being thawed have average pH about 7-9. The more density and age of frozen soil the more methane content; it could be an indirect evidence of methane producing in frozen soils. It appears that the permafrost in undisturbed taiga is characterized by the existence of high methane concentrations; values of methane concentration in air bubbles of frozen soils in the forest ranged between 1-6 ppt. However, alases (older thermokarst depressions) in some areas are distinguished by maximal methane concentrations (more than 50 ppt)
- Добавил в систему: Брушков Анатолий Викторович