Sources and sinks of methane in the African savanna. CH sub 4 emissions from biomass burning

Journal Article · Sat Apr 20 00:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JD02496· OSTI ID:5400433

Delmas, R A; Marenco, A ^[1]; Tathy, J P; Cros, B ^[2]; Baudet, J G.R. ^[3]

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1. Universite Paul Sabatier, Toulouse (France)
2. Universite Marien Ngouabi, Brazzaville (Congo)
3. Faculte des Sciences, Abidjan, (Cote d'Ivoire)

Sources and sinks of atmospheric methane are studied in savanna regions of west and central Africa. Flux measured over dry savanna soils, using static chambers, is always negative, the average uptake rate being 2 {times} 10{sup 10} molecules/cm{sup 2}/s. In these regions, sources are linked to biomass burning. Methane and CO{sub 2} emission from combustion of savanna plants and wood is studied by both field experiments and laboratory experiments using a combustion chamber. For savanna plants most of the carbon (85%) contained in the biomaterial is volatilized as CO{sub 2} and 0.1 to 0.25% as methane. For graminaceous plants like loudetia simplex the ratio C-CH{sub 4}/C-CO{sub 2} is 0.11%; it is 0.28% for hyparrhenia the other main type of savanna plants and it attains 1.4% for the combustion of wood. In natural fire plumes this ratio is around 0.26% for savanna fires and 0.56 to 2.22% for forest fires. These results show that methane release is highly dependent on the type of combustion. Methane to CO{sub 2} ratios are also studied in vertical profiles in the troposphere taken during the TROPOZ I campaign, an aerial research expedition carried out over west Africa during the bushfire period. Within polluted layers, the average ratio of CH{sub 4} to CO{sub 2} excess over ambient air concentration is 0.34%. These results show that biomass burning in tropical Africa constitutes an important source of atmospheric methane estimated to about 9.2 {times} 10{sup 6} T (CH{sub 4})/yr.

• OSTI ID: 5400433
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:D4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
095000 -- Biomass Fuels-- Environmental Aspects-- (1990-)
54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
AFRICA
ALKANES
ATMOSPHERIC CHEMISTRY
BIOMASS
CARBON
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
COMBUSTION
DEVOLATILIZATION
EARTH ATMOSPHERE
ECOSYSTEMS
ELEMENTS
EMISSION
ENERGY SOURCES
HYDROCARBONS
METHANE
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PLANTS
POLLUTION SOURCES
QUANTITY RATIO
RENEWABLE ENERGY SOURCES
SAVANNAS
SINKS
SOILS
TERRESTRIAL ECOSYSTEMS
THERMOCHEMICAL PROCESSES
TROPOSPHERE
WOOD