Atmos. Chem. Phys. Discuss., 9, 21669-21716, 2009
© Author(s) 2009. This work is distributed
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Molecular characterization of urban organic aerosol in tropical India: contributions of biomass/biofuel burning, plastic burning, and fossil fuel combustion
P. Q. Fu1, K. Kawamura1, C. M. Pavuluri1, and T. Swaminathan2
1Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
2Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India

Abstract. Organic molecular composition of PM10 samples, collected at Chennai in tropical India, was studied using capillary gas chromatography/mass spectrometry. Twelve organic compound classes were detected in the aerosols, including aliphatic lipids, sugar compounds, lignin products, terpenoid biomarkers, sterols, aromatic acids, phthalates, hopanes, and polycyclic aromatic hydrocarbons (PAHs). At daytime, phthalates was found to be the most abundant compound class; while at nighttime, fatty acids was the dominant one. Concentrations of total quantified organics were higher in summer (611–3268 ng m−3, average 1586 ng m−3) than in winter (362–2381 ng m−3, 1136 ng m−3), accounting for 11.5±1.93% and 9.35±1.77% of organic carbon mass in summer and winter, respectively. Di-(2-ethylhexyl) phthalate, C16 fatty acid, and levoglucosan were identified as the most abundant single compounds. The nighttime maxima of most organics in the aerosols indicate a land/sea breeze effect in tropical India, although some other factors such as local emissions and long-range transport may also influence the composition of organic aerosols. The abundances of anhydrosugars (e.g., levoglucosan), lignin and resin products, hopanes and PAHs in the Chennai aerosols suggest that biomass burning and fossil fuel combustion are significant sources of organic aerosols in tropical India. Interestingly, terephthalic acid was maximized at nighttime, which is different from those of phthalic and isophthalic acids. A positive correlation was found between the concentration of 1,3,5-triphenylbenzene (a tracer for plastic burning) and terephthalic acid, suggesting that field burning of municipal solid wastes including plastics is a significant source of terephthalic acid. This study demonstrates that, in addition to biomass burning and fossil fuel combustion, the open-burning of plastics also contributes to the organic aerosols in South Asia.

Citation: Fu, P. Q., Kawamura, K., Pavuluri, C. M., and Swaminathan, T.: Molecular characterization of urban organic aerosol in tropical India: contributions of biomass/biofuel burning, plastic burning, and fossil fuel combustion, Atmos. Chem. Phys. Discuss., 9, 21669-21716, doi:10.5194/acpd-9-21669-2009, 2009.
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