State Environmental Protection Key Laboratory of Formation of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai 200233, China; School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; State Key Joint Laboratory of Environmental Simulation and Pollution Control, International Joint Laboratory for Regional Pollution Control (IJRC), Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
State Environmental Protection Key Laboratory of Formation of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai 200233, China.
Sci Total Environ. 2021 Jun 1;771:144948. doi: 10.1016/j.scitotenv.2021.144948. Epub 2021 Jan 29.
The variations of non-refractory submicron aerosol (NR-PM) were characterized using an high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and other online instruments measurements sampled at an urban site in Shanghai from 2016 to 2017. Spring (from 18 May to 4 June 2017), summer (from 23 August to 10 September 2017) and winter (from 28 November 2016 to 23 January 2017) seasons were chosen for detail investigating the seasonal variations in the aerosol chemical characteristics. The average PM (NR-PM + BC) mass concentration showed little difference in the three seasons in Shanghai. The average mass concentrations of total PM during spring, summer, and winter observations in Shanghai were 23.9 ± 20.7 μg/m, 28.5 ± 17.6 μg/m, and 31.9 ± 22.7 μg/m, respectively. The seasonal difference on chemical compositions was more significant between them. Organic aerosol (OA) and sulfate were dominant contributor of PM in summer, whereas OA and nitrate primarily contribution to the increase of PM mass loading in spring and winter. As an abundant component in PM (accounting for 39%-49%), OA were resolved into two primary organic aerosol (POA) factors and two secondary aerosol (SOA) factors by using positive matrix factorization (PMF), of which OA was overwhelmingly dominated by the SOA (50-60%) across the three seasons in Shanghai. Correlation analysis with relative humidity and odd oxygen indicated that aqueous-phase processing and played an important role in more aged SOA formation in summer and winter. In spring, both aqueous-phase and photochemical processing contributed significantly to fresh SOA formation. Our results suggest the significant role of secondary particles in PM pollution in Shanghai and highlight the importance of control measures for reducing emissions of gaseous precursors, especially need to consider seasonal characteristics.
利用高分辨率飞行时间气溶胶质谱仪（HR-ToF-AMS）和其他在线仪器对 2016 年至 2017 年上海市区进行的测量，对非难溶性亚微米气溶胶（NR-PM）的变化进行了特征描述。选择春季（2017 年 5 月 18 日至 6 月 4 日）、夏季（2017 年 8 月 23 日至 9 月 10 日）和冬季（2016 年 11 月 28 日至 2017 年 1 月 23 日）进行详细研究，以调查气溶胶化学特性的季节性变化。上海三个季节的 PM（NR-PM+BC）质量浓度平均值差异不大。上海春季、夏季和冬季总 PM 质量浓度的平均值分别为 23.9±20.7μg/m、28.5±17.6μg/m和 31.9±22.7μg/m。它们之间的化学成分季节性差异更为显著。在夏季，有机气溶胶（OA）和硫酸盐是 PM 的主要贡献者，而在春季和冬季，OA 和硝酸盐主要导致 PM 质量负荷增加。OA 作为 PM 中的丰富成分（占 39%-49%），通过正定矩阵因子分解（PMF）将其分为两个主要的一次有机气溶胶（POA）因子和两个二次气溶胶（SOA）因子，在上海的三个季节中，OA 主要由 SOA（50-60%）组成。与相对湿度和奇数氧的相关分析表明，水相处理在夏季和冬季较老 SOA 的形成中起着重要作用。在春季，水相和光化学处理都对新鲜 SOA 的形成有重要贡献。我们的研究结果表明，二次粒子在上海 PM 污染中起着重要作用，并强调了减少气态前体排放控制措施的重要性，特别是需要考虑季节性特征。
