Development of gas signatures of smouldering peat wildfire from emission factors

Abstract

Smouldering peat fires are responsible for regional haze episodes and cause environmental, social and health crises. Owing to the unique burning characteristics of smouldering peat, identifying and detecting this kind of fire remains a challenge. This work explores smouldering peat gas signatures using emission factor (EF) data from literature. Systematic comparisons and statistical analyses were carried out to investigate 28 forms of EF combinations created from the four most abundant gas species: carbon dioxide (CO2), methane (CH4), carbon monoxide (CO) and ammonia, from smouldering peat, flaming savanna and grassland, agricultural residue and forest fires. Among the candidate gas signatures, the ratio of EF(CO2) to EF(CH4) for smouldering peat showed a significant improvement with statistically different ranges of values (134.6) compared to those from flaming savanna and grassland fire (940.2), agricultural residue fire (434.4), forest fire (368.8) and mixed burning peat fires (207.7). Additionally, we found that EF(CO2)/EF(CH4) is independent from fuel composition and could differentiate early ignition from the subsequent spread, making it the best gas signature among those analysed, including CO/CO2 ratio and the Modified Combustion Efficiency. This work presents the first scientific endeavour developing smouldering gas signatures, contributing to the scientific understanding and remote sensing and early detection of smouldering peat wildfires.