Emissions of CO2, CO, and hydrocarbons from fires in diverse African savanna ecosystems

Abstract

Emissions of CO2, CO, and hydrocarbons from 13 savanna fires (∼7 ha) were investigated in Zambia and South Africa in August and September 1992. The experiments were conducted at two moist woodland savanna sites, a moist grassland savanna site, and a semiarid woodland savanna site in Zambia, and nine semiarid woodland savanna sites in South Africa. The hydrocarbons measured were CH4, C2–C6alkanes, alkenes, and alkynes, and aromatic compounds. The linear relationship between the emission factor of CH4and the combustion efficiency is similar regardless of the phase of combustion (flaming or smoldering), the climatic zone, the herbaceous species, or the amount of aboveground biomass. Concentrations of emitted nonmethane hydrocarbons are linearly correlated with those of CH4. The emission ratio of a trace gas to CH4is constant for either phase of combustion in these ecosystems. Biomass burning in African savannas is a significant source of CO, ethyne, propene, and benzene in the atmosphere. The amount of CO, ethene, ethane, ethyne, propene, propane, and benzene emitted per year from these fires is about 20–95% of the amount released from global industrial activities.