材料期刊网

二次有机气溶胶是大气颗粒物的重要组成部分。有关二次有机气溶胶的分子示踪物、生成机制，以及产率的实验室研究和外场观测工作已在世界各地广泛开展；然而，学术界对二次有机气溶胶的认识仍待进一步加深，以期更为全面地了解二次有机气溶胶生成和消亡的整个大气过程。本课题组拟利用新近发展的热脱附?化学电离?飞行时间质谱技术为主要手段，从新的视角研究二次有机气溶胶的化学物种和形成机制：在烟雾箱中研究一系列生物源和人类源有机化合物与羟基自由基、硝基自由基、以及臭氧的反应，应用热脱附?化学电离?飞行时间质谱技术测定二次有机气溶胶的分子组成特征；在相对污染和相对洁净地区分别组织外场观测，着重于实际大气中二次有机气溶胶的热脱附?化学电离?飞行时间质谱技术的方法发展；实现利用烟雾箱研究获得每个前体物生成的二次有机气溶胶的指纹特征，使用多元线性回归分析技术分析实际大气中的二次有机气溶胶的前体物来源；通过相对污染和相对洁净两个地区的比较，阐明两地的大气颗粒物污染是否在化学组分方面具有类似性而只是具有浓度上的差别，或者两地的大气颗粒物污染是否由于前体物浓度上的差异而已具有化学组分上的非线性差异。

Secondary organic aerosols ( SOAs ) are one of the major components of atmospheric aerosol particles. While numerous studies on the formation mechanisms , yields , and molecular tracers of SOAs have been conducted, uncertainties in the formation and ageing of SOAs well remain. Here we propose to study molecular speciation and formation mechanisms of SOAs from a new angle offered by the newly?developed Chemical Ionization?Time?of?Flight Mass Spectrometry ( CI?ToFMS ) . Smog chamber reactions of biogenic and anthropogenic organic compounds with hydroxyl ( OH) and nitrate ( NO3 ) radicals, and ozone when applicable, will be carried out with characterization of chemical components in SOAs by CI?ToFMS equipped with a Filter Inlet for Gases and AEROsols ( FIGAERO) . Using these fingerprint?type mass spectra developed for each precursor as factor profiles, multi?factor line regression analysis of ambient data matrix obtained through field campaigns at a relatively more polluted site and a relatively less polluted site, respectively, will be performed to identify SOAs and their precursors, and to offer an insight into whether the air quality at the more polluted site is chemically similar to that in the less polluted site but at higher concentrations, or whether there are significant chemical non?linearities between the two sites.