Abstract

The volatile organic compounds (VOCs) associated with biomass burning were characterized in the Yangtze River Delta of China, including two types of burning conditions (stove burning and field burning) and five typical kinds of biomass (straws of rice, wheat, bean and rape, and wood). According to the results, the VOC emission factors of straw burning ranged from 2.08 g/kg to 6.99 g/kg with an average of (4.89 ± 1.70) g/kg, compared to 0.98 g/kg for wood burning. Some differences in VOC composition were observed with the burning of different biomasses. Oxygenated VOC (o-VOC) were the largest contributors to the mass concentration of measured VOCs from straw burning, with a proportion of 49.4%, followed by alkenes 21.4%, aromatics 13.5%, alkanes 10.6% and halogenated VOC (x-VOC) 5.0%. More aromatics and x-VOC were emitted from wood burning compared with straw burning. Field burning emitted more o-VOC due to more air being supplied during the burning test compared with stove burning. Further examination of the detailed VOC species showed the most abundant VOC species from biomass burning were o-VOC, C2–C3 alkenes and C6–C7 aromatics. The ozone formation potential (OFP) of VOCs from straw burning was in the range of 13.92–33.24 g/kg, which was much higher than that of wood burning (4.30 g/kg). Alkenes and o-VOC were the largest contributors to OFP of VOCs from biomass burning. The top five contributors of OFP were ethene, n-hexanal, propylene, acetaldehyde and methyl vinyl ketone, the sum of which accounted for 77% of total OFP. The ratio of ethylbenzene to m,p-xylenes from biomass burning was significantly higher than those from other VOC sources, and thus this could be seen as the fingerprint of biomass burning.

Highlights

  • Biomass was widely used as a biofuel in the rural of China

  • As reported in these studies, volatile organic compounds (VOCs) emission factors of biomass burning ranged over two orders of magnitude, which were affected by the ambient temperature and the types of the biomass (Wang et al, 2009)

  • We can see that the emission factor of wood burning was significantly lower than that of straw burning (t-test, p < 0.001) because the dense structure of wood slowed down its emission of the volatile components and led to a more complete burning of the volatile components during the test (Li et al, 2011)

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Summary

Introduction

Biomass was widely used as a biofuel in the rural of China. It was reported that more than 550 million tons of biomass was burned in China in year of 2005 (National Bureau of Statistics, 2006). Taking the Yangtze River Delta (YRD) as an example, Huang et al (2011) reported that the volatile organic compounds (VOCs) emission amount from biomass burning accounted for ~3.5% of total VOCs in YRD Though it did not play a significant role on an annual scale, biomass burning mostly occurred in the harvest season (i.e., in June and October) and usually caused serious regional air pollution (Li et al, 2009a). It still had some uncertainties in estimating the VOC emission from biomass burning due to the lack of local emission factors and source profiles of VOCs (Huang et al, 2011). As reported in these studies, VOC emission factors of biomass burning ranged over two orders of magnitude, which were affected by the ambient temperature and the types of the biomass (Wang et al, 2009)

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