Special Session on Better Air Quality in Asia (II)

Bo Huang1,4, Ting Gan2, Mei Li This email address is being protected from spambots. You need JavaScript enabled to view it.1,3, Peng Cheng1,3, Duohong Chen5, Lei Li1,3, Zhengxu Huang1,3, Wei Gao1,3, Zhong Fu4, Zhen Zhou1,3

1Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou, 510632, China
2Sun Yat-sen University, Guangzhou, 510275, China
3Guangdong Provincial Engineering Research Center for on-line source apportionment system of air pollution, Guangzhou, 510632, China
4Guangzhou Hexin Instrument Co., Ltd, Guangzhou, 510530, China
5Guangdong Environmental Monitoring Center, Guangzhou 510308, China


 

Received: November 13, 2019
Revised: April 1, 2020
Accepted: May 17, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.


Download Citation: ||https://doi.org/10.4209/aaqr.2019.11.0582 

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Cite this article:

Huang, B., Gan, T., Li, M., Cheng, P., Chen, D., Li, L., Huang, Z., Gao, W., Fu, Z. and Zhou, Z. (2020) Size-segregated characteristics of water-soluble inorganic ions in different seasons at Heshan of Guangdong, China. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.2019.11.0582


HIGHLIGHTS

  • Increased NOR and decreased SOR were observed during pollution days.
  • The highest SOR and NOR values were found in size ranges of 0.56–1 µ
  • NO3 in Heshan showed different formation pathways in winter and summer.
  • Size-depended SO42– formation pathways were observed.
  • Aqueous reactions accelerated by NO2 might be a possible pathway of SO42–
 

ABSTRACT


Twenty-four sets of size-segregated samples were collected in Heshan in July 2014 and January 2015 using a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) to understand the characteristics, sources, and formation mechanisms of aerosol particles during the pollution period in the Pearl River Delta region. Nine ions, including Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO2-, NO3-, and SO42- were measured. Na+, Mg2+, and Ca2+ were distributed mainly in the coarse particles, which were mostly from soil, dust, and sea salt. Fine-mode K+ in winter was mainly from burning biomass. Coarse mode Cl- was from sea salt, while fine-mode Cl- came from the redistribution of NH4Cl into the particle phase. Both SO42- and NO3- were unimodally distributed during winter but bimodally distributed in summer. The coarse mode of SO42- came from sea salt, while the coarse mode of NO3- was formed through heterogeneous reactions. An increase in the nitrogen oxidation ratio (NOR )and a decrease in the sulfur oxidation ratio (SOR) during the period of pollution were observed. The highest SOR and NOR values were found in size ranges of 0.56-1 μm. A homogeneous gas-phase reaction was the main formation pathway of NO3- in winter, while heterogeneous reactions of N2O5 during the night were predominant in summer. For SO42-, the size range of 0.056-0.32 μm was controlled by the gas-phase oxidation mechanism, while the aqueous oxidation formation pathway was common in the size range of 0.56-3.2 μm. A positive correlation between SOR and NO2 in a size range of 0.056-1.8 μm was observed, indicating a possible formation pathway of SO42- through aqueous reactions accelerated by NO2.


Keywords: water-soluble inorganic ions; size distribution; secondary formation; SOR; NOR



Aerosol Air Qual. Res. 20:-. https://doi.org/10.4209/aaqr.2019.11.0582 

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