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上海城区二次气溶胶的形成:光化学氧化与液相反应对二次气溶胶形成的影响
摘要点击 2369  全文点击 760  投稿时间:2018-12-07  修订日期:2019-01-01
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中文关键词  亚微米颗粒物  气溶胶质谱  一次有机气溶胶(POA)  二次有机气溶胶(SOA)  光化学氧化  液相反应
英文关键词  PM1  aerosol mass spectrometry  primary organic aerosol (POA)  secondary organic aerosol (SOA)  photochemical oxidation  aqueous-phase reaction
作者单位E-mail
高杰 上海大学环境与化学工程学院, 上海 200444
上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233 
jiegshu@163.com 
乔利平 上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233  
楼晟荣 上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233  
严茹莎 上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233  
周敏 上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233  
刘瑜存 上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233  
冯加良 上海大学环境与化学工程学院, 上海 200444 fengjialiang@shu.edu.cn 
黄丹丹 上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233 huangdd@saes.sh.cn 
中文摘要
      二次组分是大气细颗粒物中最重要的组成部分之一.本研究旨在探究上海城区大气气溶胶颗粒物中二次组分的贡献及其形成的主要影响因素.利用高分辨率飞行时间气溶胶质谱仪(HR-TOF-AMS)对上海城区春季及夏季的亚微米颗粒物(PM1)进行实时的在线表征,发现有机物是PM1中最主要的组成部分,占比为55%;其次是硫酸盐(24%)与硝酸盐(10%).进一步结合正交矩阵因子解析模型(PMF)对有机组分进行了来源解析.结果表明,一次有机气溶胶(POA)与二次有机气溶胶(SOA)分别占总有机物浓度的34%与66%;POA主要来自机动车源与餐饮源的贡献,且在春季和夏季对有机物的贡献趋于稳定.观测期间共观察到3个二次气溶胶显著生成的过程:其中,春季二次组分的显著增长过程以硫酸盐和老化的有机气溶胶在正午时段上升显著为主要特征,主要受光化学氧化过程的促进;夏季二次组分的显著生成过程主要是液相反应与光化学氧化共同促进的结果,如液相反应过程中,硝酸盐浓度与颗粒相水含量有较好的相关性(R2=0.72),而光化学氧化期间SOA浓度与大气氧化性(Ox)有较好的相关性.总体而言,二次组分是上海城市大气气溶胶颗粒物中最重要的组成部分,二次有机与无机组分在PM1颗粒物中占比分别为35.5%和43%,光化学氧化与液相反应对二次组分的形成有显著的促进作用.
英文摘要
      Secondary species are one of the most important components of PM1 particles. To investigate the contributions as well as the factors that affect the formation of the secondary aerosols, a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS, AMS) was employed to characterize sub-micron particles (PM1) during spring and summer in urban Shanghai. Organics were dominant in PM1 particles and comprised around 55% of the total PM1 mass concentration, followed by sulfate (24%) and nitrate (10%). Positive matrix factorization was further applied to explore the sources of the organics. It was found that primary and secondary organic aerosols accounted for around 34% and 66% of the total organics, respectively. Three episodes were observed during the measurements, where secondary species increased substantially. Increases of secondary species were represented by increases of sulfate and LV-OOA1 in spring, especially during the noontime, thus indicating that their formation is promoted by photochemical oxidation; yet in summer, photochemical and aqueous chemistry together accelerate the formation of secondary species, as indicated by the good correlations between nitrate and aerosol liquid water as well as between SOA and Ox. Overall, we found that contributions from secondary organic and inorganic aerosols to total PM1 particles were 35.5% and 43%, respectively. This study highlights that the influence of photochemical and aqueous chemistry is significant in the promotion of secondary species formation in Shanghai.

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