Molecular distribution and seasonal variation of hydrocarbons in PM2.5 from Beijing during 2006--颗粒学报PARTICUOLOGY

Li, Y., Cao, J., Li, J., Zhou, J., Xu, H., Zhang, R., & Ouyang, Z. (2013). Molecular distribution and seasonal variation of hydrocarbons in PM2.5 from Beijing during 2006. Particuology, 11(1), 78–85. https://doi.org/10.1016/j.partic.2012.09.002

Molecular distribution and seasonal variation of hydrocarbons in PM_2.5 from Beijing during 2006

Yushan Li ^{a b}, Junji Cao ^{c d *}, Jianjun Li ^c, Jiamao Zhou ^c, Hongmei Xu ^c, Renjian Zhang ^e, Zhiyun Ouyang ^a

a Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
b University of Chinese Academy of Sciences, Beijing 100049, China
c Key Laboratory of Aerosol Science & Technology, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, China
d Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an, China
e Key Laboratory of Regional Climate-Environment Research for Temperate East Asia (RCE-TEA), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

10.1016/j.partic.2012.09.002

Volume 11, Issue 1, February 2013, Pages 78-85

Received 7 July 2012, Revised 30 August 2012, Accepted 12 September 2012, Available online 21 December 2012.

E-mail: cao@loess.llqg.ac.cn

Highlights

► The n-alkanes and PAHs were characterized using a thermal desorption-GC/MS technique.

► Both n-alkanes and PAHs are highest in winter and lowest in summer.

► Correlations of PAHs with OC and EC are very different in non-heating and heating seasons.

► Comparison showed environmental protection measures performed in the past 10 years are effective.

Abstract

Normal (n)-alkanes and polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 were collected from Beijing in 2006 and analyzed using a thermal desorption-GC/MS technique. Annual average concentrations of n-alkanes and PAHs were 282 ± 96 and 125 ± 150 ng/m³, respectively: both were highest in winter and lowest in summer. C19–C25 compounds dominated the n-alkanes while benzo[b]fluoranthene, benzo[e]pyrene, and phenanthrene were the most abundant PAHs. The n-alkanes exhibited moderate correlations with organic carbon (OC) and elemental carbon (EC) throughout the year, but the relationships between the PAHs, OC and EC differed between the heating and non-heating seasons. The health risks associated with PAHs in winter were more than 40 times those in spring and summer even though the PM_2.5 loadings were comparable. Carbon preference index values (<1.5) indicated that the n-alkanes were mostly from fossil fuel combustion. The ratios of indeno[123-cd]pyrene to benzo[ghi]pyrelene in summer and spring were 0.58 ± 0.12 and 0.63 ± 0.09, respectively, suggesting that the PAHs mainly originated from motor vehicles, but higher ratios in winter reflected an increased influence from coal, which is extensively burned for domestic heating. A comprehensive comparison showed that PAH pollution in Beijing has decreased in the past 10 years.

Graphical abstract

Keywords

PM_2.5; Normal alkanes (n-alkanes); Polycyclic aromatic hydrocarbons (PAHs); Air pollution; Beijing

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