基于CMAQ/ISAM空气质量模型的北京市夏季臭氧来源解析研究

Source Apportionment of Ozone in Summer in Beijing Based on CMAQ/ISAM Air Quality Model

为了解北京市夏季臭氧(O_(3))污染的特征与来源,采用区域空气质量模型(CMAQ)的综合源解析功能(ISAM)对北京市2019年6月不同区域的近地面O_(3)浓度及其来源贡献进行了数值模拟计算,量化了北京市、天津市、河北省、京津冀以外省份以及全球背景共14类NO_(x)和VOCs排放源对北京市不同区域O_(3)污染的贡献.结果表明:①北京市不同地区O_(3)及其前体物来源存在显著差异,城区及近郊区NO_(x)和VOCs均主要来自于北京市本地排放,本地源排放对城区及近郊区的NO_(x)贡献(39.7%~46.4%)显著大于对远郊区的贡献(19.9%~38.8%),本地源排放对城区及近郊区的VOCs贡献(51.1%~75.8%)大于对远郊区的贡献(19.5%~39.6%).②远郊区NO_(x)和VOCs浓度更易受非本地排放的输送影响.③O_(3)主要来源于包括模拟区域外以及全球背景的边界传输贡献,边界传输对北京市不同受体区域的贡献均大于52.6%.④北京市本地源排放对城区及近郊区O_(3)的贡献(6.8%~18.3%)大于对远郊区的贡献(2.4%~7.6%),京津冀以外源区的排放对北京市远郊区的贡献(5.2%~6.4%)大于对城区及近郊区的贡献(2.7%~4.4%),说明本地排放对远郊区影响相对较小,远郊区O_(3)浓度易受北部燕山山脉和太行山的阻隔影响.因地理位置及地形原因,河北省不同源区对北京市不同区域O_(3)浓度的贡献存在一定差异.研究显示,控制北京市夏季O_(3)污染应综合考虑城区与郊区O_(3)来源的差异性,做好周边区域的联防联控.

In order to understand the characteristics and sources of ozone(O_(3))pollution in Beijing in summer,the Integrated Source Apportionment Method(ISAM)of the Community Multiscale Air Quality model(CMAQ)was applied to numerically simulate the near-surface O_(3) concentrations and their source contributions in different regions of Beijing in June 2019.The contributions of 14 types of NO_(x) and VOCs emission sources from Beijing City,Tianjin City,Hebei Province,provinces outside Jin-Jing-Ji Region and the global sources(contribution from outside the simulation area)to O_(3) pollution in different regions of Beijing was quantified.The results showed that:(1)There were significant differences in the sources of O_(3) and its precursors in different regions of Beijing.Both NO_(x) and VOCs in urban and suburban areas are mainly derived from local emissions in Beijing.The contribution of NO_(x) emitted by local sources to urban and suburban areas(39.7%-46.4%)was significantly greater than that of outer suburban areas(19.9%-38.8%),and the contribution of local sources to VOCs in urban and suburban areas(51.1%-75.8%)was greater than that of outer suburban areas(19.5%-39.6%).(2)NO_(x) and VOCs concentrations in remote suburban areas were more susceptible to the non-local emissions.(3)O_(3) was mainly derived from the contribution of boundary transport,including the simulated extra-regional region as well as global background,and the contribution of boundary transport to different receptor areas in Beijing exceeded 52.6%.(4)The contribution of local source emissions to O_(3) in urban and suburban areas of Beijing(6.8%-18.3%)was greater than that of outer suburbs(2.4%-7.6%),while emissions from regions outside Beijing-Tianjin-Hebei contributed to the outer suburbs of Beijing(5.2%-6.4%)was greater than the contribution to urban and suburban areas(2.7%-4.4%).It indicated that the outer suburbs had relatively small local emission characteristics and were susceptible to the blocking of Yanshan and Taihang Mountains in the north.Due to the geographical location and topographical factors,there were some differences in the contribution of different source areas in Hebei Province to different regions of Beijing.According to the research,the control of O_(3) pollution in Beijing should take into account the differences in O_(3) sources in urban and suburban areas,and do a good job in joint prevention and control in the surrounding areas.