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 (EC) 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 southwest monsoon season (June–September) than during the northeast monsoon season (December–March), and these differences were statistically significant. Conversely, the syringaldehyde concentration during the southwest 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 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 southwest 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

“…Overall, chemical speciation of OC revealed the following characteristics of peat burning emissions: high OC mass fractions (72%), primarily water-insoluble OC (84±11% C), low EC mass fractions (1%), vanillic to syringic acid ratios of 1.9, and relatively high n-alkane contributions to OC (6.2% C) with odd carbon preference CPI (1.2-1.6). This chemical profile is in good agreement with 15 prior studies of Indonesian peat burning using laboratory measurements (Christian et al, 2003;Iinuma et al, 2007) and ambient aerosol studies in Indonesia (Fujii et al, 2015a;Fujii et al, 2015b) as well as laboratory studies of peat emissions from other locations Geron and Hays, 2013;Chen et al, 2007). (Armstrong et al, 2004;Kim et al, 2013).…”

“…indicators of peatland fire emissions in previous studies that analyzed the ambient air impacted by peat smoke (Fujii et al, 2014;Fujii et al, 2015a;Fujii et al, 2015b). Some organic compounds (e.g.…”

Quantitative assessment of source contributions to PM2.5 on the west coast of Peninsular Malaysia to determine the burden of Indonesian peatland fire

“…Indonesia has the largest tropical peatland area (2.7 × 10 5 km 2 ) in the world (Joosten, 2010) and almost every dry season, peatland fires occur in Sumatra and Kalimantan Inlands. As peatland fires are usually ignited underground and can travel large distances unseen before reappearing elsewhere, they are extremely difficult to extinguish (Fujii et al, 2015b). For this reason, peatland fires pose a more serious risk of uncontrollable burning than other sources of ignitable biomass.…”

“…Dense smoke haze from Indonesian peatland fires (IPFs) causes impacts on health, visibility, transport and regional climate in Southeast Asian countries such as Indonesia, Malaysia, and Singapore (Betha et al, 2014Engling et al, 2014;Fujii et al, 2016aFujii et al, , 2015aFujii et al, , 2015bFujii et al, , 2014Harrison et al, 2009;He et al, 2010;Page et al, 2002;See et al, 2007See et al, , 2006Tacconi, 2003). PM2.5 is the main constituent of the smoke haze that is chiefly responsible for adverse health and environmental effects (See et al, 2006).…”

“…PM2.5 is the main constituent of the smoke haze that is chiefly responsible for adverse health and environmental effects (See et al, 2006). Chemical characterizations of IPF-induced smoke aerosols including PM2.5 have been conducted to investigate the contribution of IPFs to the air quality in Southeast Asia (SEA) or identify the key indicator of IPF in transboundary pollution countries or near fire sources (Abas et al, 2004a(Abas et al, , 2004bFang et al, 1999;Fujii et al, 2016aFujii et al, , 2015aFujii et al, , 2015bFujii et al, , 2014Huboyo et al, 2016;Okuda et al, 2002;See et al, 2007).…”