Sources and processes of organic aerosol in non-refractory PM1 and PM2.5 during foggy and haze episodes in an urban environment of the Yangtze River Delta, China.
Sources and processes of organic aerosol in non-refractory PM1 and PM2.5 during foggy and haze episodes in an urban environment of the Yangtze River Delta, China.
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DOI：
10.1016/j.envres.2022.113557
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发表时间：
2022-05
影响因子：
8.3
通讯作者：
Shuaiyi Li;Cheng Chen;Guang Yang;Jie Fang;Yele Sun;Li-li Tang;Hongli Wang;Wentao Xiang;Hongliang Zhang;P. Croteau;J. Jayne;H. Liao;X. Ge;O. Favez;Yunjiang Zhang
中科院分区：
文献类型：
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作者：
Shuaiyi Li;Cheng Chen;Guang Yang;Jie Fang;Yele Sun;Li-li Tang;Hongli Wang;Wentao Xiang;Hongliang Zhang;P. Croteau;J. Jayne;H. Liao;X. Ge;O. Favez;Yunjiang Zhang
有机气溶胶（OA）通常占城市大气细颗粒物（PM2.5）的很大一部分。尽管在了解亚微米气溶胶组分（PM1）的发射源、转化过程和光学性质方面取得了重大进展，但更大的组分（如PM2.5）仍值得补充研究。本研究利用两种气溶胶化学形态监测仪和870 nm光声消光仪，对长三角地区雾霾和雾霾环境下pm1和pm2.5中OA的来源、形成过程和光学特性进行了综合分析。采用多线性引擎（ME2）算法对pm1和pm2.5有机质谱进行了正矩阵分解分析。确定了4个OA因子，包括3个主要OA因子，即类烃OA （HOA）、烹饪OA （COA）和生物质燃烧OA (BBOA)，以及一个次要OA因子，即氧化氧化OA （OOA）。在烹饪高峰时段，明显观察到PM1-2.5 coa浓度的增加，表明新鲜烹饪排放的大颗粒（即PM1-2.5）有重要贡献。PM2.5HOA的氧化态和浓度均高于PM1，表明大颗粒HOA可能与氧化POA有关。在雾霾发作期间，观察到大尺度OOA对非难治性pm2.5质量的高贡献（44%）。在雾期，pm1和PM2.5OOA浓度随时间呈正相关增加，同时PM2.5-OOA与PM1-OOA之比呈指数增长。同时，在雾期，OOA负荷随气溶胶液态水含量（ALWC）的增加而增加。随机森林交叉验证分析也支持ALWC对OOA变化的重要影响，支持在雾霾和/或雾霾期间水过程对SOA形成的实质性影响。得到的结果还表明，在雾霾和雾霾期间，对pm2.5散射系数的OOA贡献高（21% ~ 36%），POA贡献低（6% ~ 14%）。大气垂直扩散和水平输运对不同粒径组分中不同主次OA因子的浓度有重要但不同的影响。
Organic aerosol (OA) generally accounts for a large fraction of fine particulate matter (PM2.5) in the urban atmosphere. Despite significant advances in the understanding their emission sources, transformation processes and optical properties in the submicron aerosol fraction (PM1), larger size fractions - e.g., PM2.5- still deserve complementary investigations. In this study, we conducted a comprehensive analysis on sources, formation process and optical properties of OA in PM1and PM2.5under haze and foggy environments in the Yangtze River Delta (eastern China), using two aerosol chemical speciation monitors, as well as a photoacoustic extinctiometer at 870 nm. Positive matrix factorization analysis - using multilinear engine (ME2) algorithm - was conducted on PM1and PM2.5organic mass spectra. Four OA factors were identified, including three primary OA (POA) factors, i.e., hydrocarbon-like OA (HOA), cooking OA (COA), and biomass burning OA (BBOA), and a secondary OA (SOA) factor, i.e., oxidized oxygenated OA (OOA). An enhanced PM1-2.5COA concentration was clearly observed during cooking peak hours, suggesting important contribution of fresh cooking emissions on large-sized particles (i.e., PM1-2.5). The oxidation state and concentration of PM2.5HOA were higher than that in PM1, suggesting that large-sized HOA particles might be linked to oxidized POA. High contribution (44%) of large-sized OOA to non-refractory PM2.5mass was observed during haze episodes. During foggy episodes, PM1and PM2.5OOA concentrations increased as a positive relationship over time, along with an exponential increase in the PM2.5-OOA to PM1-OOA ratio. Meanwhile, OOA loadings increased with the aerosol liquid water content (ALWC) during foggy episodes. Random forest cross-validation analysis also supported the important influence of ALWC on OOA variations, supporting substantial impact of aqueous process on SOA formation during haze and/or foggy episodes. Obtained results also indicated high OOA contributions (21%–36%) and low POA contributions (6%–14%) to the PM2.5scattering coefficient during haze and foggy episodes, respectively. Finally, we could illustrate that atmospheric vertical diffusion and horizontal transport have important but different effects on the concentrations of different primary and secondary OA factors in different particle size fractions.