Constraining the emission of particulate matter from Indonesian peatland burning using continuous observation data

Tropical peatland, which dominantly distributes in Indonesia and Malaysia, has experienced recurring fires in the last few decades. Constraining the enhancement ratios and emission factors of gas and particulate matter emitted by the wildfires is necessary to evaluate their environmental and climatic impacts. We analyzed continuous observation data at Pekanbaru in Indonesia and Muar in Malaysia to investigate the emissions of gas and particulate matter. The enhancement ratios of particulate matter to carbon monoxide (PM10/CO) of wildfires in Riau province in June 2013 and February–March 2014 were analyzed. The PM10/CO ratios of peatland burning plumes ranged from 77 to 97 μg mg−1 for the event in June 2013, whereas the corresponding value was 127 μg mg−1 in February–March 2014. These enhancement ratios were translated to the emission factors of particulate matter using previous data on the emission factors of CO, assuming that secondary formation was ignorable. The estimated emission factors for PM10 were 13 ± 2 g kg−1 (2013) and 19 ± 2 g kg−1 (2014). These values are comparable to those reported by recent field observations in Indonesia and Malaysia (17.3 ± 6.0 to 34.4 ± 18.8 g kg−1). The estimated emission factors from both the present study and recent field work are consistently higher than that used in the current emission inventory, which suggests that it should be updated. A caveat for this analysis is possible influence of secondary formation, which will still be needed to be investigated in future studies.