青岛春节期间大气污染特征及烟花燃放一、二次贡献分析

我国北方地区冬季采暖期大气污染事件频发，期间硝酸盐成为促进PM_2.5增加的主要因素.然而在烟花燃放期间，硫酸盐的累积却强于硝酸盐，形成不同的污染特征.对春节期间（2019年2月2~10日）青岛近郊在线离子色谱观测数据，结合国控自动监测站数据进行综合分析.结果表明，研究期间观测到大气颗粒物累积事件、沙尘过境事件和烟花燃放事件.烟花燃放高峰期，其对PM_2.5和PM₁₀的一次贡献率分别为69.8%和63.8%.相比颗粒物累积期间硝酸盐有更明显的累积，硫酸盐在烟花燃放期间先于硝酸盐生成，并存在更强的累积.分离得到烟花燃放的一次贡献因子n（SO₄^2-）/n（K⁺）和n（NO₃^-）/n（K⁺）特征摩尔比分别为1.2和1.3；利用该比值估算得到对SO₄^2-和NO₃^-二次贡献因子，在较稳定的气象条件下分别为一次贡献因子的2.1倍和1.6倍；但在强的干冷空气过境时，二次贡献因子大幅降低，与一次贡献因子相当.

Analysis of Pollution Characteristics and Primary, Secondary Contributions of Firework Burnings in Qingdao During the Spring Festival

Atmospheric pollution frequently occurs in northern China during winter heating period, wherein nitrate became the dominant driver for PM_2.5 accumulations. However, sulfate accumulation was found to be significantly higher than that of nitrate during firework burning events and exhibited different pollution characteristics. Online data available from February 2, 2019 to February 10, 2019, including observation data measured from AIM-IC in suburban Qingdao and meteorological data from national automatic monitoring station, were analyzed. The results showed that particulate accumulation, dust and firework burning events were observed. The primary contribution rates of the most intensive firework burning to PM_2.5 and PM₁₀ were 69.8% and 63.8%, respectively. In contrast to a severe accumulation of nitrate during the particulate accumulation event, the sulfate formed prior and exhibited more severe accumulation than nitrate during the firework burning events. The primary contribution factors n(SO₄^2-)/n(K⁺) and n(NO₃^-)/n(K⁺) of firework burnings was 1.2 and 1.3 (molar ratios), respectively. The secondary contribution factors were 2.1 and 1.6 times, under relatively stable meteorological conditions. However, during the transit of dry and cold air, the value of secondary contribution factors decreased substantially and exhibited nearly the same values as the primary ones.