摘要
于2019年10月17日—11月16日在南京北郊地区,采用SMPS⁃CCNC联用的方式,对8.2~346 nm的气溶胶粒子展开了粒径分辨的CCN活化特征观测.根据PM_(2.5)浓度范围选取了清洁天和污染天进行分析发现,在高污染大气背景下,由于有机物浓度及占比较高,无机盐浓度较低,故CCN活化率低于清洁天.清洁天SOA组分占比较高,其大气氧化经历更长,氧化态更高,吸湿参数κ也更高;污染天在受到直接排放的影响下,大气氧化经历短,氧化态较低,POA占比相对较高,所以清洁天的吸湿参数κ大于污染天κ(0.28±0.07>0.24±0.09).清洁天的f_(44)平均值为0.14±0.02,污染天的f44平均值为0.12±0.02,进一步表明清洁天的有机气溶胶氧化态更高.因此,高污染大气背景下由于大气中存在很多受排放影响的积聚模态的气溶胶,含有很多低吸湿性物质,降低了CCN的活化能力和吸湿性.
From October 17th to November 16th,2019,the size⁃resolved CCN activation properties of atmospheric particles with a diameter ranging from 8.2 nm to 346 nm were measured using a SMPS⁃CCNC combination method at the northern suburb of Nanjing.According to the PM_(2.5) mass loading,clean and polluted days were classified for analysis separately and we found that during the heavily polluted days,the aerosol CCN activation ratio was lower than that during the clean days due to the higher concentration of organic components but lower concentration of inorganic salts.During clean days,the SOA components,mainly from pre⁃existing aerosols are relatively higher due to longer exposure to atmospheric oxidation,leading to higher oxidation state and thus higher values of hygroscopicity parameterκ.During polluted days,on the other hand,higher POA portion was observed due to much stronger direct emissions and shorter atmospheric processing time,hence leading to lower oxidation state.Therefore,the hygroscopicity parameterκin clean days was larger than that in polluted days(0.28±0.07>0.24±0.09).The average of f_(44) of clean days was 0.14±0.02 comparing to 0.12±0.02 of polluted days,which further indicates that the oxidation state of organic components was higher during clean days.Therefore,in highly polluted environment,the hygroscopicity and CCN activation capability of accumulation mode aerosols were reduced due to the high influence from primary emissions by contributing less hygroscopic substances.
作者
谌菲
马嫣
郑军
CHEN Fei;MA Yan;ZHENG Jun(School of Environmental Science and Engineering,Nanjing University of Information Science&Technology,Nanjing 210044;Reading Academy,Nanjing University of Information Science&Technology,Nanjing 210044;Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control,Nanjing 210044)
出处
《环境科学学报》
CAS
CSCD
北大核心
2021年第12期5063-5072,共10页
Acta Scientiae Circumstantiae
基金
大气污染防治攻关项目(No.DQGG0103⁃02)
国家自然科学基金资助项目(No.41730106,41975172)
国家重点研发计划项目(No.2017YFC0209501)。
关键词
云凝结核
活化特性
昼夜变化
POA
cloud condensation nuclei
activation properties
diurnal variation
primary organic aerosol
