TRACE GAS EMISSIONS FROM TROPICAL BIOMASS FIRES - YUCATAN PENINSULA, MEXICO

Mixing ratios for carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H-2), methane (CH4) and total non-methane hydrocarbons (TNMHC) were determined from the smoke plumes of two small (approximately 0.25 ha) prescribed biomass fires conducted on the Yucatan Peninsula in Mexico. In the region of these fires the combination of climate and shallow soils produces a scrubby and stunted forest with species composition similar to the Brazilian rain forest, but at a noticeably reduced size. Aircraft collections of smoke from these fires were analysed and used to determine CO2-normalized emission ratios (DELTAX/DELTACO2; v/v; where DELTA = in-plume specie concentration less background concentration) for CO, H-2, CH4 and TNMHC produced and released into the atmosphere from these fires. Surprisingly, high mean emission ratios for TNMHCs (approximately 1.7% of CO2 release) and H-2 (approximately 2.5% of CO2) were determined. Emission ratios for CO (approximately 7%) and CH4 (approximately 0.7%), however, were found to fall within expected bounds.