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  广州地化所发现我国秋冬季萜烯类二次有机气溶胶升高与生物质燃烧有关  
  2017/04/10 | 【  

  生物质燃烧(biomass burning)是全球最重要的有机气溶胶一次排放源,其排放的大量反应性气体(如萜烯和氮氧化物等)又会生成二次有机气溶胶(SOA),对全球和区域气候环境产生直接和间接影响。萜烯类化合物(异戊二烯、单萜烯和倍半萜)是全球最重要的SOA前体物。当前,学术界普遍认为萜烯类化合物主要受控于自然源排放,几乎所有模式在研究萜烯类SOA气候环境效应时,都使用MEGAN模型(The Model of Emissions of Gases and Aerosols from Nature)进行自然源排放估算,忽略其他排放源的贡献。 

  中国科学院广州地球化学研究所王新明课题组的丁翔博士,通过对覆盖全国6个区域的12站点进行同步观测,发现春夏季异戊二烯和单萜烯SOA时空变化符合MEGAN参数预测,表明其主要受自然源排放控制。然而在秋冬季,异戊二烯和单萜烯SOA浓度升高的现象,无法用MEGAN模型解释,而倍半萜烯SOA高值则大多出现在秋冬季。运用有机标志物分析的结果显示,在自然源排放显著降低的秋冬季,我国萜烯类SOA升高与生物质燃烧排放增强密切相关(1)。进一步对来源解析的结果显示,我国萜烯类SOA夏季以异戊二烯为主,其他季节主要来自单萜烯,我国已有的模型结果与实测有显著差异(2)。相关结果为全面评估萜烯类SOA气候环境效应提供了新的来源信息。 

  该研究受到中国科学院先导专项、国家自然科学基金、青年创新促进会专项资金资助。论文发表于J. Geophys. Res.-Atmos.Sci. Rep.     

  Ding, X.; Zhang, Y.-Q.; He, Q.-F.; Yu, Q.-Q.; Shen, R.-Q.; Zhang, Y.; Zhang, Z.; Lyu, S.-J.; Hu, Q.-H.; Wang, Y.-S.; Li, L.-F.; Song, W.; Wang, X.-M., Spatial and seasonal variations of secondary organic aerosol from terpenoids over China. Journal of Geophysical Research: Atmospheres 2016, 121, 14661–14678. (论文链接 http://dx.doi.org/10.1002/2016JD025467)    

  Ding, X.; He, Q.-F.; Shen, R.-Q.; Yu, Q.-Q.; Zhang, Y.-Q.; Xin, J.-Y.; Wen, T.-X.; Wang, X.-M., Spatial and seasonal variations of isoprene secondary organic aerosol in China: Significant impact of biomass burning during winter. Scientific Reports 2016, 6, 10.1038/srep20411. (论文链接http://dx.doi.org/10.1038/srep20411)   

  1异戊二烯SOA春夏季变化趋势符合MEGAN模型(CL*CT),秋冬季背离,与生物质燃烧标志物(Levoglucosan)正相关    

  2 我国萜烯类SOA组成以及与已有模型结果对比 

 

 

  Biomass burning causes unexpected increases of terpenoids secondary organic aerosols in autumn and winter over China 

  Biomass burning (BB) is the most important source of global primary organic aerosols. During the process of BB, large amounts of reactive gases (e.g. terpenoids and NOx) are released into the air and further produce substantial secondary organic aerosols (SOA), which significantly affects global climate change and regional air quality. As the most important SOA precursors on a global scale, terpenoids (isoprene, monoterpenes, and sesquiterpenes) are believed to be mainly emitted from biogenic sources. Almost all models that probe the impact of terpenoids SOA on climate and environment only consider biogenic emissions and use MEGAN (The Model of Emissions of Gases and Aerosols from Nature) to estimate terpenoids emissions. 

  The scientists at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS) discover that BB causes unexpected increases of terpenoids SOA in autumn-winter over China.   Based on a one-year concurrent observation of terpenoids SOA tracers at 12 sites across 6 regions of China, they find that the spatiotemporal trends of isoprene and monoterpenes SOA in spring-summer are indeed consistent with the prediction of MEGAN parameters, suggesting the majority of biogenic emissions for isoprene and monoterpenes then. However, unexpected increases of terpenoids SOA in autumn-winter cannot be explained by MEGAN parameters. The positive correlations between terpenoids SOA tracers and the BB tracer, levoglucosan in autumn-winter indicate that the unexpected increases of terpenoids SOA are highly associated with the enhancement of BB (Figure 1). Source apportionment results implicate that the composition of terpenoids SOA dramatically changes from a monoterpene majority in fall-spring to an isoprene majority in summer, which cannot fully predicted by current modeling studies (Figure 2). These findings highlight the importance of terpenoids emissions from BB and provide new insight into the sources of terpenoids SOA. These results have been published in Journal of Geophysical Research: Atmospheres and Scientific Reports 

  This research is supported by the Strategic Priority Research Program of Chinese Academy of Science (CAS), the National Science Foundation of China, and the Youth Innovation Promotion Association, CAS.      

  Ding, X.; Zhang, Y.-Q.; He, Q.-F.; Yu, Q.-Q.; Shen, R.-Q.; Zhang, Y.; Zhang, Z.; Lyu, S.-J.; Hu, Q.-H.; Wang, Y.-S.; Li, L.-F.; Song, W.; Wang, X.-M., Spatial and seasonal variations of secondary organic aerosol from terpenoids over China. Journal of Geophysical Research: Atmospheres 2016, 121, 14661–14678. (http://dx.doi.org/10.1002/2016JD025467) 

  Ding, X.; He, Q.-F.; Shen, R.-Q.; Yu, Q.-Q.; Zhang, Y.-Q.; Xin, J.-Y.; Wen, T.-X.; Wang, X.-M., Spatial and seasonal variations of isoprene secondary organic aerosol in China: Significant impact of biomass burning during winter. Scientific Reports 2016, 6, 10.1038/srep20411. (http://dx.doi.org/10.1038/srep20411)     

  Figure 1 Variation trend of isoprene SOA is consistent with the predication of MEGAN parameters (CL*CT) in autumn-winter, but not so in autumn-winter. Positive correlations are observed between isoprene SOA tracers and the BB tracer, levoglucosan in autumn-winter. (Image by DING Xiang)     

  Figure 2 Seasonal changes in terpenoids SOA composition over China, and comparison between field observation and model prediction. (Image by DING Xiang) 

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