Characteristics of complex air pollution in typical cities of North China

目前京津冀地区夏季面临非常严重的大气复合污染。2014年北京、天津、石家庄观测资料分析表明,京津冀地区PM2.5年平均超过国家二级标准的2–3倍,夏季O3八小时滑动平均值超过标准1–2倍。当温度超过20°C、湿度低于55%时,O3与PM2.5协同增长,大气复合污染显著。同时,对比三个地区同步观测发现,当高浓度PM2.5下降时,太阳辐射增强,臭氧浓度将进一步上升。这使得京津冀地区大气污染治理面临更大挑战,当治理首要颗粒物污染时,臭氧浓度将会快速上升,造成严重的光化学污染。

The Beijing-Tianjin-Hebei urban agglomeration is currently facing severe complex air pollution. In this paper, simultaneous observations conducted in 2014 show that the annual mean concentration of fine particulate matter （PM2.5） was 84 ± 70, 86 ±60, and 118 ± 95 μg m-3 in Beijing, Tianjin, and Shijiazhuang, respectively. The mean 03 8h max in the summer was 171 ± 43, 147 ± 45, and 146 ± 44 μg m-3, respectively. This research indicates that PM2.5 and O3 are positively correlated when the temperature exceeds 20 ℃5 and the urban agglomeration shows characteristics of complex air pollution consisting of superimposed 03 and PM2.s. In summer, when the humidity was less than 55%, secondary particles and 03 also increased in a coordinated manner （y = 1.35x ＋ 29.85; R2 = 0.61）, which demonstrates severe complex pollution. However, the mean PM2.5（y） and mean 03 8 h max （x） in summer showed a negative correlation （y = - 1.3x ＋ 245; R2 = 0.61 ） in the three regions, indicating high concentrations of PM2.5 pollution partially inhibit O3 generation.