Effect of fuel composition on combustion efficiency and emission factors for African savanna ecosystems

Savanna burning in Africa occurs over a wide range of environmental, vegetation, and land use conditions. The emission factors for trace emissions from these fires can vary by a factor of 6 to 8, depending on whether the fires burn in miombo woodlands or in ecosystems where grass vegetation dominates. Ground-based measurements of smoke emissions and aboveground biomass were made for fires in grassland and woodland savanna ecosystems in South Africa and Zambia. A high combustion efficiency ( η⌢) was measured for the pure grassland; i.e., a high proportion of carbon was released as CO2. The η⌢ was lower for woodland savanna ecosystems with variable amounts of grass and with a more compact layer of leaf material and litter lying near the ground. The η⌢ was found to be dependent on the ratio of grass to the sum of grass and litter. Models developed for estimating emissions were integrated in a nomogram for estimating total emissions of CO2, CO, CH4, nonmethane hydrocarbons, and particles of less than 2.5 μm diameter per unit area.

[1]  D. Ward,et al.  Smoke emissions from wildland fires , 1991 .

[2]  W. Hao,et al.  Methane production from global biomass burning , 1993 .

[3]  C. Justice,et al.  Satellite remote sensing of fires during the SAFARI campaign using NOAA Advanced Very High Resolution Radiometer data , 1996 .

[4]  Patrick R. Zimmerman,et al.  Hydrocarbon and carbon monoxide emissions from biomass burning in Brazil , 1984 .

[5]  W. Hao,et al.  Emissions of CO2, CO, and hydrocarbons from fires in diverse African savanna ecosystems , 1996 .

[6]  P. Crutzen,et al.  Biomass Burning in the Tropics: Impact on Atmospheric Chemistry and Biogeochemical Cycles , 1990, Science.

[7]  D. Ward,et al.  Fuel biomass and combustion factors associated with fires in savanna ecosystems of South Africa and Zambia , 1996 .

[8]  Yoram J. Kaufman,et al.  Smoke and fire characteristics for cerrado and deforestation burns in Brazil: BASE-B experiment , 1992 .

[9]  Wei Min Hao,et al.  Spatial and temporal distribution of tropical biomass burning , 1994 .

[10]  C. Justice,et al.  Emissions of trace gases and aerosol particles due to vegetation burning in southern hemisphere Africa , 1996 .

[11]  C. Everson,et al.  Fire Management in Southern Africa: Some Examples of Current Objectives, Practices, and Problems , 1990 .

[12]  D. Jacob,et al.  Biomass‐burning emissions and associated haze layers over Amazonia , 1988 .

[13]  P. Andrews.  BEHAVE : Fire Behavior Prediction and Fuel Modeling System - BURN Subsystem, Part 1 , 1986 .

[14]  P. Riggan,et al.  Particulate and trace gas emissions from large biomass fire in North America , 1991 .

[15]  James K. Brown.  Handbook for inventorying downed woody material , 1974 .