Sulfur Gas Emissions from African Savanna-Burning

Abstract

To study fluxes and factors controlling the emission of sulfur gases from biomass-burning, field experiments have been conducted in an African savanna area during the dry season (January 1989 and 1991). During these experiments, COS, SO2, CO2, and CO have been simultaneously monitored. SO2 and COS values range from 0.1 and 0.6 ppbv out of the fires to 115 and 42 ppbv in the plume, respectively. A significant correlation has been observed between COS and CO concentrations (R = 0.96), indicating a COS production during the smoldering combustion. SO2 correlates with CO2 (R = 0.92), indicating production during the flaming combustion. The increase in COS/CO2 ratios (ΔCOS/ΔCO2) during field experiments ranged from 3 x 10-6 to 61 x 10-6 (12 x 10-6 mean value). COS emission from biomass-burning is estimated to be up to 0.02 Tg S/yr in African savanna areas and up to 0.07 Tg S/yr on a global basis, thus contributing about 10% to the global COS flux. Concerning SO2, emission factor (ΔSO2/ΔCO2) ratios ranged from 27 x 10-6 to 65 x 10-6 (mean value 47 x 10-6) during field experiments. Biomass-burning is estimated to release up to 0.3 Tg S/yr, which do not represent a significant SO2 source on a global scale.