基于观测数据的石家庄交通干线附近臭氧光化学敏感性分析

为确定石家庄东部郊区交通干线附近O₃生成光化学敏感性,利用2019年1月1日—2020年10月31日在线观测的NO_x、NO_y和O₃等数据计算并分析了O₃生成效率(OPE)及O₃光化学敏感性的NO_x临界浓度.结果表明:1交通干线附近O₃光化学敏感性存在季节差异,春季主要受VOCs控制,整体OPE为2.6±0.3,夏、秋季节主要受NO_x与VOCs协同控制,整体OPE分别为5.3±0.4和5.1±0.8;2NO_x体积分数>11×10^-9时,O₃生成主要为VOCs控制;NO_x体积分数介于6×10^-9~11×10^-9时,O₃生成主要受VOCs与NO_x协同控制;NO_x体积分数<6×10^-9时,O₃生成主要为NO_x控制;3O₃生成敏感性存在日变化特征,10:00之前O₃生成主要受VOCs控制,10:00—11:00是O₃生成由VOCs控制转变为VOCs和NO_x协同控制的过渡时段,12:00之后O₃生成主要由VOCs和NO_x协同控制,且午后14:00—16:00之间NO_x对O₃控制比例凸显.因此,石家庄O₃治理不但要重视NO_x与VOCs排放源的协同管控,尤其午后还需要对NO_x排放源进行分时段精细化管控.

Analysis on the ozone formation sensitivity based on observation at the traffic trunk roads of Shijiazhuang

In order to study the formation sensitivity of ozone at the Traffic Trunk Roads site located in the eastern suburbs of Shijiazhuang, ozone production efficiency (OPE) and critical NO_x concentration was calculated and analyzed using the on-line data from 1 January 2019 to 31 October 2020. The observed results were listed following: 1The formation sensitivity of ozone was of significantly seasonal variation. OPE was 5.3±0.4 and 5.1±0.8 in summer and autumn, respectively, controlled by synergistic effect of NO_x and VOCs. While the OPE in spring was 2.6±0.3, and mainly controlled by VOCs. 2The NO_x volume fraction was less than 6×10^-9, between 6×10^-9 and 11×10^-9, and greater than 11×10^-9 correspond to that the ozone formation limited by NO_x, NO_x-VOCs and VOCs, respectively. 3The ozone formation sensitivity was daily variant, controlled by the NO_x critical concentration. The transformation period when the ozone formation gradually transferred from being VOCs-sensitive to NO_x-VOCs-sensitive was from 10:00 to 11:00. The ozone formation was VOCs-sensitive before 10:00, and was limited by NO_x-VOCs after 12:00, and the ozone formation sensitivity to NO_x increased in the afternoon. Thus, the ozone management in Shijiazhuang should not only pay attention to the coordinated control of NO_x and VOCs emission sources, especially in the afternoon, but also need to carry out time-divided fine control of NO_x emission sources.