深圳大运会前后大气含碳气溶胶污染特征

2011年8月12~24日,深圳市成功举办了第26届世界大学生运动会.为保证空气质量,两个观测点的PM2.5(空气动力学直径?2.5μm的大气颗粒物)质量浓度均值分别为(12.99±3.73)μg/m3和(25.24±5.20)μg/m3.然而,8月24日(含)大运会结束、主要污染控制措施取消之后,PM2.5的质量浓度呈现台阶式突增,测得观测点所处位置PM2.5分别为(48.01±8.73)μg/m3和(54.05±6.53)μg/m3.为探讨大气颗粒物污染水平变化的原因,对大运会结束前后深圳市大气含碳气溶胶的变化特征进行了分析,利用元素碳示踪法对大运会结束前后的一次和二次含碳气溶胶污染水平进行估算,结果显示大运会结束后的2个观测点的一次有机碳估算浓度较大运会期间增长了55%和22%,二次有机碳分别增长了442%和169%.结合气象因素及后向轨迹聚类模型的分析结果,认为在大运会结束后的大气颗粒物浓度阶梯状增加的原因除本地污染累积外,污染气团远距离传输以及气象条件都对阶梯型污染有一定的贡献.

Characterization of carbonaceous aerosols during and post-Shenzhen UNIVERSIADE period

The 26th UNIVERSIADE, and event that (briefly describe, including PM2.5 controls that were put in place) was successfully held in Shenzhen during Aug.12th ~ 24th, 2011. Monitored PM2.5 (aerodynamic diameter?2.5μm) mass concentrations measured (12.99±3.73) μg/m3 and (25.24±5.20) μg/m3 at two selected sampling sites. However, significant increase in PM2.5 mass appeared after the UNIVERSIADE, when the control measures were terminated. At this time, PM2.5 mass concentrations were (48.01±8.73) μg/m3 and (54.05±6.53) μg/m3, respectively. In this study, elemental carbon was used as a tracer to estimate the contamination levels of primary and secondary carbonaceous aerosols both during and after the UNIVERSIADE event. Results show that primary organic carbon post-UNIVERSIADE increased by 55% and 22% and the secondary organic carbon increase by 442% and 169% at the two sites, respectively. Considering meteorological factors and backward trajectory clustering modeling, both long-distance particle transportation and local contamination accumulation contribute to the air quality degradation, among which secondary atmospheric reactions might be the major factor leading to the observed PM2.5 increase.