碳质气溶胶是大气细颗粒物(PM2.5)的重要组成部分,对全球气候变化具有重要影响。大气能见度,区域空气质量,和人类健康。为探讨减排背景下碳质气溶胶的长期变化特征,有机碳(OC)浓度,PM2.5样品中的元素碳(EC),通过实时在线监测得到2018-2021年成都市挥发性有机物(VOCs)及相应的气象因子。结果表明,监测期间ρ(OC)和ρ(EC)平均为(10.9±5.7)μg·m-3和(2.6±1.9)μg·m-3,分别占PM2.5的25.2%和6.0%。平均ρ(SOC)为(5.7±3.3)μg·m-3,占OC的52.9%。OC的浓度,EC,和PM2.5在2018-2020年呈下降趋势[PM2.5:浓度年均下降-7.1μg·(m3·a)-1,年均下降-14.6%·a-1;OC:-1.7μg·(m3·a)-1,-14.2%·a-1;EC:-0.1μg·(m3·a)-1,-4.4%·a-1],与2020年相比,2021年各污染物浓度在不同范围内回升。PM2.5和OC的浓度如下:冬季>春季>秋季>夏季,EC的浓度如下:冬季>秋季>春季>夏季。夏季和秋季OC和EC的比例高于其他季节,平均比例分别为26.8%和6.9%,分别。随着污染程度的加剧,OC,EC,SOC浓度逐渐增加,但是PM2.5的比例呈现逐渐下降的趋势,说明成都市PM2.5污染的控制因素不是碳组分。源解析结果表明,成都市碳质气溶胶主要受机动车,工业来源,生物质燃烧源,和VOCs二次反应。从2019年到2021年,EC受到机动车特征部件的影响,并且逐年下降。春季和秋季OC和EC受VOCs的影响大于其他季节。春季和秋季应加大VOCs排放管理,以减少二次反应的影响。
Carbonaceous aerosol is an important component of atmospheric fine particulates (PM2.5) that has an important effect on global climate change, atmospheric visibility, regional air quality, and human health. In order to investigate the long-term change characteristics of carbonaceous aerosols under the background of emission reduction, the concentrations of organic carbon (OC), elemental carbon (EC) in PM2.5 samples, and volatile organic compounds (VOCs) in Chengdu from 2018 to 2021 and the corresponding meteorological factors were obtained through real-time online monitoring. The results showed that the average ρ(OC) and ρ(EC) during the monitoring period were (10.9 ±5.7) μg·m-3 and (2.6 ±1.9) μg·m-3, accounting for 25.2% and 6.0% of PM2.5, respectively, and the average ρ(SOC) was (5.7 ±3.3) μg·m-3, accounting for 52.9% of OC. The concentrations of OC, EC, and PM2.5 showed a downward trend from 2018 to 2020 [PM2.5: The concentration of average annual decrease was -7.1 μg·(m3·a) -1, with an average annual decrease of -14.6 %·a-1; OC: -1.7 μg·(m3·a)-1, -14.2 %·a-1; EC: -0.1 μg·(m3·a)-1, -4.4 %·a-1], and the concentrations of each pollutant in 2021 rebounded in different ranges compared with those in 2020. The concentrations of PM2.5 and OC were as follows: winter > spring > autumn > summer, and the concentrations of EC were as follows: winter > autumn > spring > summer. The proportions of OC and EC were higher in summer and autumn than in other seasons, with the average proportions of 26.8% and 6.9%, respectively. With the aggravation of the pollution level, OC, EC, and SOC concentrations gradually increased, but the proportions in PM2.5 showed a gradual downtrend, indicating that the control factor of PM2.5 pollution in Chengdu was not the carbon component. Source apportionment results showed that carbonaceous aerosols in Chengdu were mainly affected by motor vehicles, industrial sources, biomass combustion sources, and VOCs secondary reaction. From 2019 to 2021, EC was affected by the characteristic components of motor vehicles and decreased yearly. OC and EC were affected by VOCs more in spring and autumn than in other seasons. VOCs emission management should be increased in spring and autumn to reduce the impact of secondary reaction.