Sources and sinks of atmospheric methane |
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Authors: | D. H. Ehhalt U. Schmidt |
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Affiliation: | (1) Institut für Chemie 3, Atmosphärische Chemie, Kernforschungsanlage Jülich GmbH, D-5170 Jülich, BRD |
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Abstract: | In 1972 average mixing ratio of methane in the troposphere was 1.41 ppm and 1.3 ppmv for the northern and southern hemisphere, respectively, which corresponds to a total amount of 4×1015 g of CH4 present in the atmosphere. Most is of recent biologic origin.14C analyses show that no more than 20 percent is released by fossil sources. The various ecosystems producing CH4 are discussed and the total annual production is estimated to lie between 5.5×1014 g/yr and 11×1014 g/yr. The corresponding turnover times for atmospheric CH4 range from 4 to 7 yrs. The destruction of CH4 takes place mainly in the troposphere, most probably through the reaction of CH4 + OH CH3 + H2O. About 10 percent of the CH4 is destroyed in the stratosphere. The CH4 cycle contributes on the order of 1 percent to the atmospheric carbon cycle. |
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Keywords: | Trace gases Atmosphere Sources and Sinks Methane |
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