北京市大兴区大气中过氧乙酰硝酸酯的监测与特征研究

Monitoring and Characteristics of Peroxyacetyl Nitrate in the Atmosphere of Beijing Daxing

通过研究大气中过氧乙酰硝酸酯(PAN)的浓度变化特征,为光化学污染防治提供依据。采用PAN在线分析仪对2019年7月18日~8月31日北京市大兴区的大气PAN进行观测。结果显示:观测期间PAN摩尔分数日均值在0.26~1.83 nmol/mol之间,晴天中PAN浓度相对较高,阴雨天PAN浓度相对较低;夏季PAN浓度日变化规律显著,呈典型单峰形态,最高值通常出现在下午13:00~15:00;PAN浓度与O3浓度变化趋势基本一致,具有较强的相关性,导致PAN生成的VOCs物种在总反应性VOCs中所占比例持续降低。仅通过O3浓度变化不能全面表征光化学污染程度,需综合分析PAN与O3等的监测数据,才能更好的评估光化学污染事件及污染程度,从而采取更有效的防治措施。

The article studies the characteristics of atmospheric peroxyacetyl nitrate(PAN) concentration changes to provide a basis for photochemical pollution prevention and control. A PAN online analyzer was used to observe the atmospheric PAN from July 18, 2019 to August 31, 2019 in Daxing district, Beijing. The results showed that:The daily average PAN concentrations during the observation period ranged from 0.26 nmol/mol to 1.83 nmol/mol, with relatively high PAN concentrations in clear weather and relatively low PAN concentrations in rainy weather;The daily variation pattern of PAN in summer is significant, with a typical single-peak pattern, and the highest values usually occur between 13 : 00 and 15 : 00;The trends of PAN and O3 concentrations are basically the same, with a strong correlation, leading to a continuous decrease in the proportion of PAN-generated VOCs species in the total reactive VOCs. Characterizing the degree of photochemical pollution by O3 concentration changes alone is still not comprehensive, and monitoring data of PAN and O3, etc. need to be analyzed comprehensively to better assess photochemical pollution events and pollution levels, so that more effective prevention and control measures can be taken.