上海西南区域春季一次典型光化学污染过程分析

为研究上海西南区域O₃的污染形成机制，对该区域2020年4月10—20日近地面O₃、NO₂、VOCs和气象数据进行分析.结果表明:①研究期间，日最高温度仅18.3℃，但O₃日最大8 h滑动平均体积分数达91.6×10-9，φ（O₃）小时增长率最大为1 950%；东风风速较大时O₃污染频发，说明该区域φ（O₃）的高值主要受到来自东部输送的污染源驱动.②O_x主要组分为O₃，平均占比为74.6%；当φ（O₃）/φ（O_x）在0.65~0.85之间时，φ（O₃）增长速率较快.③烯烃类VOCs排放增多是导致φ（O₃）增大的主要原因.④PMF源解析得到5个排放源，分别为石化源与机动车尾气、LPG（液化石油气）和NG（天然气）燃烧源、制药排放源、精细化工排放源以及石化烯烃源，其中对OFP贡献较大的为烯烃和芳香烃类，二者占比分别为21.3%和34.6%，主要物种分别为乙烯和间/对-二甲苯.研究显示，春季低温下上海西南区域O₃污染频发，主因是污染源驱动，φ（O₃）高值受远距离前体物输送的影响较大. 

Typical Springtime Photochemical Pollution Process in Southwestern Shanghai

In order to study the formation mechanism of O₃ pollution in southwestern Shanghai, the O₃, NO₂, volatile organic compounds (VOCs) and meteorological data in this area from April 10th to 20th, 2020 were analyzed. The results show that: (1) During the study period, the daily maximum temperature was only 18.3 ℃, but the maximum 8-hour sliding average of O₃ per day reached 91.6×10-9, and the hourly growth rate of the volume fraction of φ(O₃) reached 1950%. O₃ pollution occurred frequently with high east wind, indicating that the high value of φ(O₃) was mainly driven by pollution sources from the east. (2) O_x was the main component of O₃, with an average proportion of 74.6%. When φ(O₃)/φ(O_x) was between 0.65 and 0.85, φ(O₃) increased at a faster rate. (3) The increase in olefin VOCs emissions was the main reason for the increase in φ(O₃). (4) PMF source analysis indicated 5 emission sources, namely petrochemical sources and vehicle exhaust, liquefied petroleum gas (LPG) and natural gas (NG) combustion sources, pharmaceutical emission sources, fine chemical emission sources, and petrochemical olefin sources. The largest contribution of VOCs to OFP was olefins and aromatic hydrocarbons, accounting for 21.3% and 34.6% respectively. The main species were ethylene and meta/para, xylene. This study showed that O₃ pollution occurred frequently in this area under low temperature in spring, which was mainly driven by pollution sources, and the high value of φ(O₃) was greatly affected by the long-distance transportation of precursors.