1Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
2College of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China
3Nanjing Tianbo Environmental Technology Co., Ltd, Nanjing 210047, China
1Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
2College of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China
3Nanjing Tianbo Environmental Technology Co., Ltd, Nanjing 210047, China
Received: 24 Jan 2018 – Accepted for review: 02 Feb 2018 – Discussion started: 05 Feb 2018
Abstract. Secondary aerosols including inorganic and organic components often dominate the fine aerosol mass, it is thus important to elucidate the formation and characteristics of these species. In this work, we measured the submicron aerosols (PM1) by using an Aerodyne high resolution soot-particle aerosol mass spectrometer in suburban Nanjing, China. The site was surrounded by industry plants, and the measurement was conducted during cold seasons (February–March 2015). We found that under such environment, the PM1 was predominantly comprised of secondary species (on average 63.2 % from ammonium sulfate and nitrate). Results show that moisture plays a key role to enhance both nitrate and sulfate formations. The moisture promotes the gas-particle partitioning and nocturnal heterogeneous production of nitrate, while transformation of SO2 into sulfate directly in aqueous phase is more significant. The organic aerosol (OA) occupied ~1/4 of total PM1 mass, and the primary OA (POA) and secondary OA (SOA) contributions were almost equal. A specific industry-related OA was separated and a modified graphical method was introduced to describe the evolution of OA. Results further show that the most abundant OA factor, which is the one with highest oxidation degree, is also mainly driven by aqueous-phase processing, while the other two less oxygenated SOA factors are mainly governed by photochemical processing. Peak sizes of sulfate, nitrate and OA all shifted towards larger sizes with the increases of relative humidity, reflecting the effects of aqueousphase processing too. Aqueous-phase driven secondary aerosols were found to be very important in enhancing the PM1 pollution, while photochemical processed SOA was important to OA pollution, leading to a fresher OA at higher OA concentrations. We further demonstrated influences of the aqueous-phase processing and photochemical processing on formation of secondary aerosols by using two typical cases, respectively. This paper highlights the importance of aqueous-phase chemistry on sulfate and nitrate formations, and that different portions of SOA can be dominated by different mechanisms in an industrialized environment.
This work presents results regarding the secondary aerosol formations in suburan Nanjing, a site downwind of an industrial zone. We show that under such an industrialized environment, secondary species overwhelmingly dominate the fine particle mass, and moisture (relative humidity) is critical in enhancing formations of sulfate, nitrate and the most oxygenated portion of OA, while less oxygenated secondary OA was mainly driven by photochemical processing.
This work presents results regarding the secondary aerosol formations in suburan Nanjing, a site...
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