Methane global budget

Tans P. P. (1997) A note on isotopic ratios and the global atmospheric methane budget. Global Biogeochem. Cycles 11, 77-81. 

The quantum efficiencies for these different channels vary with wavelength. The values quoted in Chapter 4 (see also Brownsword et al., 1997) for Lyman a excitation need to be confirmed. CH2 produced by two of these channels reacts rapidly with 02 to form CH20 + O, HCO + OH, CO + H20 and C02 + H2 (or H + H). The photolysis of methane produces atomic and molecular hydrogen. However, since the amount of methane in the upper part of the middle atmosphere is small, CH4 photolysis can generally be neglected in the global atmospheric methane budget. 

Table 8.1 Estimates of the global methane budget (Tg CH4 year ) from different sources and sinks...

The first global CH4 budgets were compiled by Ehhalt (1974) and Ehhalt and Schmidt (1978), who used available published information to estimate emissions of CH4 to the atmosphere. They considered paddy fields, freshwater sources (lakes, swamps, and marshes), upland fields and forests, tundra, the ocean, and enteric fermentation by animals as biogenic sources. Anthropogenic sources included industrial natural gas losses and emission from coal mining, and were considered to be free. Observations of CH4 placed an upper limit on anthropogenic sources. Oxidation by the OH radical, as well as loss to the stratosphere by eddy diffusion and Hadley circulation, were presumed to be methane sinks. In spite of lack of data, this work correctly identified the major atmospheric sources and did... 

Lassey K. R., Lowe D. C., and Manning M. R. (2000) The trend in atmospheric methane S C and implications for isotopic constraints on the global methane budget. Global Biogeochem. Cycles 14, 41—49. 

Reeburgh W. S. (1996) Soft Spots in the global methane budget. In 8th International Symposium on Microbial Growth on C-1 Compounds (eds. M. E. Lidstrom and F. R. Tabita). Kluwer, Dordrecht, pp. 334-342. 

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