摘要
Based on online observations of fine particulate matter(PM2.5) for five consecutive years from January 2013 to December 2017 in Beijing, combined with simultaneous measurement of gaseous precursors and meteorological parameters, the evolution and meteorological causes of fineparticle explosive growth(FPEG) events were analyzed. During the 5-year observation period,132 FPEG events were observed and these events were further divided into three types(3-, 6-, and 9-h events) according to their evolution duration. The majority of FPEG events were observed in winter under the conditions of higher gas precursor concentrations and unfavorable meteorological conditions. The average concentration of PM2.5 during winter FPEG events changed little from 2013 to 2016, whereas it decreased significantly in 2017, in accordance with the similar variation of gaseous species(SO2, NO2, and CO). In addition, the higher wind speeds and lowest relative humidity observed in 2017 were also conducive to the decrease in PM2.5. The evolutions of FPEG events and normal haze episodes were analyzed, revealing that the rate of increase in NO2 was much greater than that of SO2, suggesting more of a contribution from mobile sources than stationary sources. The polar Plot results suggest that the transportation from the southeast area of Beijing plays a major role in the formation of 3-h events, whereas local emissions is the main contributory factor for 9-h events and normal haze episodes. However, further quantitative analysis regarding the contributions of these factors is still needed.
本文详细分析了2013–2017年北京地区细颗粒物爆发增长事件的演变特征,并结合气态前体物和常规气象要素对3种事件类型(3h, 6h和9h事件)的污染来源及其气象成因进行了探讨。北京地区细颗粒物爆发增长事件呈逐年下降趋势,且多发生在秋冬季;事件的生消过程中NO2的增长速率远高于SO2,表明移动源的贡献要高于固定源。风向-风速-PM2.5的polar Plot结果表明,来自北京东南方向气团的污染物输送对于3h事件有较大影响, 9h事件受主要受局地排放及二次转化的影响, 6h事件则源于局地排放和区域传输的共同贡献。
基金
This study was supported by The Ministry of Science and Technology of the people's Republic of China:[Grant Numbers 2017YFC0210000 and 2016YFC0202700]
the National Natural Science Foundation of China:[Grant Number 41705110].
