The atmospheric distribution of CH4 is rather uniform zonally andvertically but exhibits a slight gradient with latitude in the troposphere;in the stratosphere it shows a definite decrease with altitude. Theaverage volume mixing ratio in the troposphere is 1.4 ppm which correspondsto a total amount of 4 � 1015 g of CH4 present in the atmosphere.Most is of recent biologic origin. C14 analyses show that no morethan 20% is released by fossil sources. The various ecosystems producingCH4 are discussed and the total annual production is estimated tolie between 5.5 � 1014 g/yr and 11 � 1014 g/yr. The correspondingturnover times for atmospheric CH4 range from 4 to 7 yr. The destructionof CH4 takes place mainly in the troposphere, most probably throughthe reaction CH4 + OH --> CH3 + H2O. About 10% of the CH4 is destroyedin the stratosphere. The CH4 cycle is strongly coupled to the H2and CO cycles and contributes also on the order of 1% to the atmosphericcarbon cycle.
CITATION STYLE
Ehhalt, D. H. (1974). The atmospheric cycle of methane. Tellus A: Dynamic Meteorology and Oceanography, 26(1–2), 58. https://doi.org/10.3402/tellusa.v26i1-2.9737
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