Emissions of gaseous pollutants from laboratory-based fires of vegetation from five common vegetation types in Western Australia

This study investigated emission factors (EFs) for CO2, CO, NO and carbonyls from laboratory-based combustion of five typical vegetation types of Western Australia. A range of combustion conditions was obtained by controlling the vegetation moisture content and air flow rate. CO2, CO and NO were measured using a multi-gas monitor MultiRAE. Six carbonyls were collected using 2,4-DNPH sorbent tubes and analysed using HPLC-UV. Burns of woodland (Banksia) and forest (Jarrah) had significantly higher EFCO, with lower modified combustion efficiency (MCE) than those of tropical grass (Spinifex). Temperate grass (Veldt) fires had lower EFCO2 and higher EFCO and EFcarbonyls, and a much lower MCE than those of the tropical grass fires. EFNO were similar for woodland, forest and tropical grass but large differences in EFNO were observed for Spinifex and Veldt grass. Formaldehyde was the most abundant carbonyl emitted. Combustion conditions influenced the EFcarbonyls with larger EFs from burns with higher fuel moisture contents and/or at higher flow rates. Functions to extrapolate EFs for infrequently measured carbonyls (acetaldehyde, acetone and propionaldehyde) from EFformaldehyde were developed. The EFCO2 and EFCO were similar to values reported from field measurements for similar ecosystems in Australia, indicating the applicability of these laboratory-based results. EFs for other gases differed to those reported from bushfires in other parts of the world suggesting that to improve prediction of bushfire emissions and impacts in Australia, EFs of all fire-prone Australian vegetation types should be determined, particularly for those in close proximity to densely populated areas.