污染物减排背景下北京大气颗粒物化学组成变化特征

Variation Characteristics of Chemical Composition of Atmospheric Particulate Matter in Beijing Under the Background of Pollutant Emission Reduction

通过搜集整理历史文献中的观测数据,对污染物减排背景下北京市大气颗粒物浓度及组成的变化特征进行分析。结果表明,在污染物减排第一阶段(1998—2008年),PM_(2.5)中有机物占比最多,其次是二次无机盐,无机盐中硫酸盐(SO_(4)^(2-))占比最多;第二阶段(2009—2012年),PM_(2.5)中二次无机盐占比最多,其次是有机物,SO_(4)^(2-)仍为二次无机盐的主要组分;第三阶段(2013—2017年),在PM_(2.5)中二次无机盐占比最多,其次是有机物,二次无机盐中硝酸盐(NO^(-)_(3))占比超过SO_(4)^(2-)。同时,于2019年在北京城市站点和森林站点分别进行为期一个月的观测实验,以探究现阶段北京大气颗粒物的特征。观测数据分析表明,北京城市和郊区的大气颗粒物组分存在较为明显的差异,在城市中NO^(-)_(3)浓度约为SO_(4)^(2-)的2倍,而在森林中SO_(4)^(2-)浓度约为NO^(-)_(3)的1.5倍。同时两站点均受区域传输影响,不同来源的气团对颗粒物浓度的影响较为明显。本研究结果为进一步推进大气污染防治提供科学依据。

By collecting and sorting the observation data in the historical literature, the variation characteristics of atmospheric particulate matter concentration and composition in Beijing under the background of pollutant emission reduction are analyzed. The results show that in the first stage of pollutant emission reduction(1998—2008), organic matter accounts for the most in PM_(2.5), followed by secondary inorganic salts, and sulfate(SO_(4)^(2-)) accounts for the most in secondary inorganic salts;In the second stage(2009—2012), PM_(2.5)has the largest proportion of secondary inorganic salt, followed by organic matter, and SO_(4)^(2-)is still the main component of secondary inorganic salt;In the third stage(2013—2017), secondary inorganic salts accounted for the most in PM_(2.5), followed by organics, and nitrate(NO^(-)_(3)) accounted for more than SO_(4)^(2-). At the same time, a one month observation experiment was conducted at Beijing urban station and forest station in 2019 to explore the characteristics of atmospheric particulate matter in Beijing at the present stage. The analysis of observation data shows that there are obvious differences in the composition of atmospheric particulate matter between urban and suburban areas of Beijing. In the city, the concentration of NO^(-)_(3)is about twice that of SO_(4)^(2-), while in the forest, the concentration of SO_(4)^(2-)is about 1.5 times that of NO^(-)_(3). At the same time, both stations are affected by regional transmission, and the influence of air masses from different sources on particle concentration is more obvious.