杨帆,王体健,束蕾,赵明,陈璞珑,李蒙蒙,杨丹丹,王静,徐少才.青岛沿海地区一次臭氧重污染过程的特征及成因分析[J].环境科学学报,2019,39(11):3565-3580
青岛沿海地区一次臭氧重污染过程的特征及成因分析
- Characteristics and mechanisms for a heavy O3 pollution episode in Qingdao coastal area
- 基金项目：国家自然科学基金（No.41575145，91544230）；国家重大科技研发项目（No.2017YFC0209803，2016YFC0208504）
- 摘要：近年来，青岛市夏季臭氧（O3）污染逐渐严重，深入分析青岛的O3变化特征和重污染形成机理对该地区大气污染防治具有重要意义.本文基于青岛大气监测站2017年6月1-20日的O3小时浓度数据，分析了发生在青岛沿海地区的一次持续O3重污染过程的特征，并利用数值模式进行成因分析.结果表明，本次污染过程10个监测站日最大8 h平均臭氧浓度超标率达到30%~45%，超标倍数为0.20~0.51，单站小时浓度峰值可达390 μg·m-3.同时，利用WRF-CMAQ模型对O3重污染过程进行了数值模拟、过程分析和敏感性试验.结果表明，WRF-CMAQ具有模拟臭氧重污染的能力，6月8-9日、15-16日O3重污染主要是外部输送导致，可能的机制是上游高空的高浓度O3沿气团轨迹传输，随下沉气流聚集在青岛西南部海面，随后由近地层西南向海风水平输送至青岛沿岸，而6月17日O3重污染产生的首要因素是局地光化学生成.本次臭氧污染期间，青岛大部分时间都处于前体物非敏感区，且覆盖范围广.2017年6月1-20日青岛沿海地区的臭氧污染事件大部分归因于区域传输，因此，应该加强区域联防联控，减少区域传输对城市臭氧浓度的影响.
- Abstract：Summertime ozone (O3) pollution in Qingdao, China, has become more and more serious in recent years. Therefore, it is of importance to investigate the underlying mechanisms responsible for the pollution so that mitigation strategies can be implemented. From the ozone data at 10 monitoring stations in Qingdao during June 1-20, 2017, we observed heavy pollution episodes from June 8-9 and June 15-17. During the episodes, the peak hour-concentration of a station reached 390 μg·m-3, daily maximum 8-hour average O3 exceeded the national standard (160 μg·m-3) by 0.20~0.51 with standard exceeding ratios of 30%~45%. We used WRF-CMAQ to numerically simulate the pollution processes and found that the simulation and observation are in good agreement. We also carried out simulation experiments and analyzed the pollution evolutions. The results show that the heavy ozone pollution on 17 June 2017 is mainly due to local photochemical production, while the pollution on June 8-9, 15-16, 2017 is a result of inflow of pollution from external regions. Specifically, high ozone in the upwind regions was transported along trajectories from the high altitudes, descending to the sea surfaces in the areas southwest of Qingdao, and then flowing to the coast of Qingdao. Simulation experiments show that ozone in Qingdao is non-precursor sensitive for most of the times, indicating that surface ozone in Qingdao is not mainly affected by local emissions and the ozone pollution episodes are mostly attributed to regional transport. Therefore, collective efforts of regional mitigation strategies should be strengthened to reduce the impact of regional transport on urban ozone pollution.
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