大气气溶胶有机氮在线检测及其二次形成机理研究

Despite the fact that atmospheric organic nitrogen (ON) can significantly affect human health, ecosystem, environment and the earth's climate system, due to its chemical complexity, currently qualitative and quantitative chemical characterization of ON is still very difficult. This project, at the first time, aims to establish a novel method by using Aerodyne soot particle aerosol mass spectrometer (SP-AMS) for characterizing atmospheric ON; and this approach will be utilized for the real-time online ON measurements in the Yangtze River Delta area, so as to determine the temporal variations, major chemical classes and sources of ON in this region. Moreover, for an important class of ON species – amines, we systematically conduct a series of smog chamber experiments to mimic its atmospheric oxidation process. By using a suite of advanced analytical techniques, particularly the high resolution SP-AMS and chemical ionization mass spectrometer (HR-CIMS), we are able to elucidate in details the formation mechanism of OH radical, NO3 radical and O3-initiated secondary organic aerosol (SOA) from aliphatic amines, thoroughly characterize both the gaseous and particle-phase products, and furthermore, derive the SOA yields of different amine precursors. Comparing the smog chamber data with real-world aerosol data, we can evaluate the contribution of amine-SOA to the total aerosol mass. The research findings of this work will greatly enhance current understanding on the environmental impacts of atmospheric ON/amines.

大气有机氮对人体健康、生态环境及地球气候系统均有着重要影响，然而由于其组成复杂，对其进行定性及定量检测分析仍是当前大气污染化学研究中的难点。本课题将首先建立一套基于黑碳-气溶胶质谱仪（SP-AMS）的大气有机氮表征方法，并用于长三角地区气溶胶有机氮的实时在线检测中，弄清该地区有机氮的污染水平、典型污染物种类及来源；此外，针对一类重要的有机氮化物即有机胺，拟在烟雾箱中模拟其大气氧化过程，使用SP-AMS、化学电离质谱仪及其他高时间分辨率仪器，详细阐明有机胺与OH、NO3和O3氧化反应生成二次有机气溶胶（SOA）的机理，全面表征其反应产物及SOA产率；与外场数据对比分析，评估有机胺SOA对实际气溶胶的贡献。项目成果对于衡量和评估有机氮/有机胺的大气环境影响有重要意义。

大气有机氮作为气溶胶的重要组成部分，其对生态系统、气候变化以及人体健康都有重要的影响。本研究从有机氮的浓度特征、来源解析以及质谱特征出发探究了长三角地区有机氮气溶胶的演变特征及来源特征。主要结果包括：水溶性有机氮是水溶性总氮的重要组分，约贡献15%左右，并且与二次离子有较好的相关性，表明WSON主要来自于二次转化。采样AMS质谱仪发展和改进了大气有机氮的分析方法，建立了相应的质谱数据库，总结了不同官能团有机氮化物的谱图特征，尤其是有机胺的指纹离子，并在离线气溶胶样品中得到应用。对硝酸盐生成驱动力进行研究发现，热动力学驱动，光化学驱动，行星边界层（PBL）的动态驱动均可以影响硝酸盐的生成。本项目的研究揭示了有机氮对大气污染防治的重要性，同时也为大气中有机氮的检测评估提供重要依据。