深圳市城区VOCs对PM2.5和O3耦合生成影响研究

为了探究珠江三角洲城市大气PM_2.5和O₃的协同污染特征,在深圳市大学城开展了秋季光化学反应活跃季大气污染加强观测.发现O₃日最大8h平均值(O₃_8h)和PM_2.5在日间具有较强的正相关关系,且O₃_8h与典型挥发性有机物(VOCs)甲醛的相关性显著高于NO₂.利用气溶胶质谱仪在线测量了亚微米气溶胶化学组成,并利用正交矩阵因子模型(PMF)对其中有机气溶胶进行来源解析,解析出5类因子,其中二次有机气溶胶(SOA)占总有机物浓度的50%.通过对污染物之间的相关性分析发现,O₃_8h和SOA具有良好的相关性,但与硝酸盐(NO₃^-)未表现出相关性,说明VOCs在深圳城区大气PM_2.5和O₃耦合生成过程中的作用比NOx明显,VOCs减排是深圳市协同控制PM_2.5和O₃污染的关键.

Research on the influence of VOCs on the coupling generation of PM2.5 and O3 in Shenzhen

In order to explore the synergistic characteristics of PM_2.5 and O₃ of the urban atmosphere in PRD region, an enhanced observation of air pollution was performed in autumn, when the photochemical reactions are more active, at Shenzhen university town. The maximum 8hours average of O₃ (O₃_8h) showed strong positive relationship with PM_2.5 and the correlation of O₃_8h with formaldehyde, a typical volatile organic compounds (VOCs), is stronger than that with NO₂. The aerosol mass spectrometer was used to measure the chemical composition of submicron aerosol online. Five types of organic aerosols (OA) were resolved by positive matrix factorization (PMF), of which the secondary organic aerosol (SOA) accounted 50% of the bulk OA. According to the correlation analysis between various pollutants, O₃_8h showed strong correlation with SOA, but no obvious correlation with nitrate (NO₃^-). The correlation analysis demonstrates that VOCs play a more important role than NO_x in the coupling formation process of atmospheric fine particles and O₃ in Shenzhen urban areas, and VOCs emission reduction is the key to collaborative control of PM_2.5 and O₃ pollution in Shenzhen.