MEASUREMENTS OF TRACE GASES EMITTED BY AUSTRALIAN SAVANNA FIRES DURING THE 1990 DRY SEASON

During 18-23 July 1990, 31 smoke samples were collected from an aircra ft flying at low altitudes through the plumes of tropical savanna fire s in the Northern Territory, Australia. The excess (above background) mixing ratios of 17 different trace gases including CO2, CO, CH4, seve ral nonmethane hydrocarbons (NMHC), CH3CHO, NO(x) (= NO + NO2), NH3, N 2O, HCN and total unspeciated NMHC and sulphur were measured. Emission ratios relative to excess CO2 and CO, and emission factors relative t o the fuel carbon, nitrogen or sulphur content are determined for each measured species. The emission ratios and factors determined here for carbon-based gases, NO(x), and N2O are in good agreement with those r eported from other biomass burning studies. The ammonia data represent the first such measurements from savanna fires, and indicate that NH, emissions are more than half the strength of NO(x) emissions. The emi ssions of NO(x), NH3, N2O and HCN together represent only 27% of the v olatilised fuel N, and are primarily NO(x) (16%) and NH, (9%). Similar ly, only 56% of the volatilised fuel S is accounted for by our measure ments of total unspeciated sulphur.