Chemical composition of waste burning organic aerosols at landfill and urban sites in Delhi

Abstract

Organic composition of total suspended particles collected from an open waste burning landfill site and an urban site of Delhi, one of the most populated cities of Asia was studied. Among the organic compounds detected, fatty acids were found to be the most abundant class of compounds at both the sites, urban (16823 ng m−3) as well as landfill site (1218120 ng m−3). As a single compound detected (on average), levoglucosan (2925 ng m−3) was found to be most abundant at urban site, whereas C18:0 fatty acid (76090 ng m−3) dominated at the landfill site. Levoglucosan contributed up to 87% of total identified sugars at urban and 86% at landfill site, suggesting biomass burning to be one of the major contributors of sugar compounds, and a possible influence of landfill waste burning on urban aerosols. CPI value for n-alkanes was close to unity at both sites (0.81 at landfill and 1.27 at urban site) indicating the anthropogenic nature of the aerosols. A predominance of tere-phthalic acid (42555 ng m−3) was found in aerosol samples collected at landfill site because of plastic enriched waste burning activity. Except 4- hydroxybenzoic acid, all other lignin and resin products are first time reported to be released by open waste burning activities in the present study. We also found a strong positive correlation between di-isobutyl phthalate and di-n-butyl phthalate at both urban (r2 = 0.94) and landfill site (r2 = 0.86), suggesting them to be the commonly used plasticizers, and plastics to be a main constituent of municipal waste. Since, the waste burning at landfill sites is a common practice either to reduce waste heaps or be it a self-ignited burning leading to significant emissions, we report the chemical composition of organic aerosols originating from such emissions. The information presented in this paper may further be useful in estimating the contribution of municipal waste burning aerosols on urban burden of particulate matter.