Annual variations of carbonaceous PM<sub>2.5</sub> in Malaysia: influence by Indonesian peatland fires

Abstract

Abstract. In this study, we quantified carbonaceous PM2.5 in Malaysia through annual observations of PM2.5, focusing on organic compounds derived from biomass burning. We determined organic carbon (OC), elemental carbon and concentrations of solvent-extractable organic compounds (biomarkers derived from biomass burning sources and n-alkanes). We observed seasonal variations in the concentrations of pyrolyzed OC (OP), levoglucosan (LG), mannosan (MN), galactosan, syringaldehyde, vanillic acid (VA) and cholesterol. The average concentrations of OP, LG, MN, galactosan, VA and cholesterol were higher during the southwestern monsoon season (June–September) than during the northeastern monsoon season (December–March), and these differences were statistically significant. Conversely, the syringaldehyde concentration during the southwestern monsoon season was lower. The PM2.5 OP / OC4 mass ratio allowed distinguishing the seven samples, which have been affected by the Indonesian peatland fires (IPFs). In addition, we observed significant differences in the concentrations between the Indonesian peatland fire (IPF) and other samples of many chemical species. Thus, the chemical characteristics of PM2.5 in Malaysia appeared to be significantly influenced by IPFs during the southwestern monsoon season. Furthermore, we evaluated two indicators, the vanillic acid / syringic acid (VA / SA) and LG / MN mass ratios, which have been suggested as indicators of IPFs. The LG / MN mass ratio ranged from 14 to 22 in the IPF samples and from 11 to 31 in the other samples. Thus, the respective variation ranges partially overlapped. Consequently, this ratio did not satisfactorily reflect the effects of IPFs in Malaysia. In contrast, the VA / SA mass ratio may serve as a good indicator, since it significantly differed between the IPF and other samples. However, the OP / OC4 mass ratio provided more remarkable differences than the VA / SA mass ratio, offering an even better indicator. Finally, we extracted biomass burning emissions' sources such as IPF, softwood/hardwood burning and meat cooking through varimax-rotated principal component analysis.

Chemical characterization of fine particulate matter emitted by peat fires in Central Kalimantan, Indonesia, during the 2015 El Niño

“…7). This value agrees well with observations of VA : SA in PM 2.5 in Malaysia affected by Sumatran peat fires, which had a VA : SA ratio of 1.7 ± 0.4 (Fujii et al, 2015b) and the ratio of vanillyl phenols to syringyl phenols of 2.0 reported for Kalimantan peat (Orem et al, 1996). Meanwhile, other studies indicate lower VA : SA ratios for near-source emissions of Sumatran peat burning (1.1 ± 0.4) (Fujii et al, 2015a) and laboratory burning of South Sumatran peat (0.11) (Iinuma et al, 2007).…”

“…Because other biomasses in South Asia have VA : SA that fall in this range, such as bamboo (1.17) and sugar cane (1.78) , this ratio is unlikely to be useful in distinguishing peat burning from other types of biomass burning in the absence of other distinguishing chemical or physical properties. Further, syringyl compounds degrade more quickly in peat compared to vanillyl compounds (Orem et al, 1996) and post-emission SA degrades more quickly than VA by photolysis in the atmosphere, such that VA : SA is likely to increase with smoke transport (Fujii et al, 2015b). Consequently, this ratio has limited utility in source identification and apportionment.…”

Time effects of high particulate events on the critical conversion point of ground-level ozone

“…Malaysia, Singapore and Indonesia) have been reported in many studies in terms of primary observations during the event (Othman et al, 2014) and direct impacts on ecosystems, environmental outcomes and economic losses (Velasco and Rastan, 2015). In addition, several studies have investigated the characteristics and composition of particulates (Fujii et al, 2015;Zhou et al, 2015;Ahmed et al, 2016), the link between aerosol optical depth and free space optics (Maghami et al, 2015;Malik and Singh, 2015), transboundary smoke-haze dispersion (Reid et al, 2013) and numerical modelling (Reddington et al, 2014).…”

Chemical characterization of biomass burning and sea spray aerosol

“…26,84,85,93 Biomass burning emissions not only elevated the PM levels at the source, it also can transport over long distance and lead to regional and global climate, socioeconomic and health effects. 130,131 Biomass burning emissions primarily contain gaseous carbonaceous species (e.g. CO 2 , CO, CH 4 ) and also rich in particulate carbonaceous species, elemental carbon (EC) and organic carbon (OC).…”

“…Levoglucosan, mannosan, syringaldehyde, vanillin, syringic acid, vanillic acid and n-alkanes are such biomass burning tracers suggested in previous studies by analyzing the ambient air impacted by peat smoke. 156,226,227 Some organic compounds (e.g. PAHs) are highly enriched in peat smoke compared to raw peat biomass, showing over 100 times greater concentration in smoke than soil indicating they formed during combustion.…”