- Formation of secondary species in submicron particulate matter (PM1) in downtown Shanghai-episodic analysis
- 上海市环境科学研究院, 国家环境保护城市大气复合污染成因与防治重点实验室, 上海 200233
- Abstract：This study presents the real-time high-resolution aerosol mass spectrometry measurements of submicron non-refractory particulate matter (NR-PM1) in urban Shanghai from August to September 2016 with the aim to identify the major episodes, formation mechanisms of the secondary species and factors that potentially affect their formation. Overall, secondary species were dominant in PM1 particles, including secondary organic aerosol (SOA), inorganic sulfate and nitrate, with each of them contributing equally to the total PM1 mass concentration. One clean period and two episodes were identified during the campaign. Secondary species in clean period were largely formed through local photochemical processes. The episodic events can be further divided into three stages, transportation, accumulation and dissipation. SOA was likely to form locally through photochemical oxidation in transportation and dissipation stages, while SOA was more affected by aerosol liquid water content (LWC) and regional transport in accumulation period. During episodic events, inorganic nitrate significantly formed locally especially during the periods when LWC was high; yet inorganic sulfate was mainly affected by regional transport.