Insights into the formation of secondary organic carbon in the summertime in urban Shanghai

查看全文 作　　者：Ci [1]Zhang;Xiaohui [1]Lu;Jinghao [1]Zhai;Hong [1]Chen;Xin [1]Yang;Qi [1,2]Zhang;Qianbiao [3]Zhao;Qingyan [3]Fu;Fei [4]Sha;Jing [4]Jin

机构地区：[1]Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering,Fudan University,Shanghai 200433,China;[2]Department of Environmental Toxicology, University of California,Davis,CA 95616, United States;[3]Shanghai Environmental Monitoring Center,Shanghai 200235, China;[4]Environment Management Bureau of Shanghai Pudong New Area,Shanghai200125, China

出　　处：《Journal of Environmental Sciences》索引2018年第30卷第10期,共15页

基　　金：supported by the National Natural Science Foundation of China(Nos.91544224,21507010,41775150);the Ministry of Science&Technology of China(No.2012YQ220113-4);the Changjiang Scholars program of the Chinese Ministry of Education 摘　　要：To investigate formation mechanisms of secondary organic carbon(SOC) in Eastern China,measurements were conducted in an urban site in Shanghai in the summer of 2015. A period of high O_3 concentrations(daily peak > 120 ppb) was observed, during which daily maximum SOC concentrations exceeding 9.0 μg/(C·m^3). Diurnal variations of SOC concentration and SOC/organic carbon(OC) ratio exhibited both daytime and nighttime peaks. The SOC concentrations correlated well with O_x(= O_3+ NO_2) and relative humidity in the daytime and nighttime, respectively, suggesting that secondary organic aerosol formation in Shanghai is driven by both photochemical production and aqueous phase reactions. Single particle mass spectrometry was used to examine the formation pathways of SOC. Along with the daytime increase of SOC, the number fraction of elemental carbon(EC) particles coated with OC quickly increased from 38.1% to 61.9% in the size range of 250–2000 nm, which was likely due to gas-to-particle partitioning of photochemically generated semi-volatile organic compounds onto EC particles. In the nighttime, particles rich in OC components were highly hygroscopic, and number fraction of these particles correlated well with relative humidity and SOC/OC nocturnal peaks. Meanwhile, as an aqueous-phase SOC tracer, particles that contained oxalate-Fe(III) complex also peaked at night. These observations suggested that aqueous-phase processes had an important contribution to the SOC nighttime formation. The influence of aerosol acidity on SOC formation was studied by both bulk and single particle level measurements, suggesting that the aqueous-phase formation of SOC was enhanced by particle acidity. 关键词：器官上海城市碳夏日 SOC 相对湿度粒子团

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Insights into the formation of secondary organic carbon in the summertime in urban Shanghai

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