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Effects of NH3 and alkaline metals on the formation of particulate sulfate and nitrate in wintertime Beijing

Huang, R-J., Duan, J., Li, Y., Chen, Q., Chen, Y., Tang, M., Yang, L., Ni, H., Lin, C., Xu, W., Liu, Y., Chen, C., Yan, Z., Ovadnevaite, J., Ceburnis, D., Dusek, U., Cao, J., Hoffmann, T. & O'Dowd, C. D., 15-May-2020, In : Science of the Total Environment. 717, 8 p., 137190.

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DOI

  • Ru-Jin Huang
  • Jing Duan
  • Yongjie Li
  • Qi Chen
  • Yang Chen
  • Mingjin Tang
  • Lu Yang
  • Haiyan Ni
  • Chunshui Lin
  • Wei Xu
  • Ying Liu
  • Chunying Chen
  • Zhen Yan
  • Jurgita Ovadnevaite
  • Darius Ceburnis
  • Uli Dusek
  • Junji Cao
  • Thorsten Hoffmann
  • Colin D. O'Dowd

Sulfate and nitrate from secondary reactions remain as the most abundant inorganic species in atmospheric particle matter (PM). Their formation is initiated by oxidation (either in gas phase or particle phase), followed by neutralization reaction primarily by NH3, or by other alkaline species such as alkaline metal ions if available. The different roles of NH3 and metal ions in neutralizing H2SO4 or HNO3, however, are seldom investigated. Here we conducted semi-continuous measurements of SO42-, NO3-, NH4+, and their gaseous precursors, as well as alkaline metal ions (Na+, K+, Ca2+, and Mg2+) in wintertime Beijing. Analysis of aerosol acidity (estimated from a thermodynamic model) indicated that preferable sulfate formation was related to low pH conditions, while high pH conditions promote nitrate formation. Data in different mass fraction ranges of alkaline metal ions showed that in some ranges the role of NH3 was replaced by alkaline metal ions in the neutralization reaction of H2SO4 and HNO3 to form particulate SO42- and NO3-. The relationships between mass fractions of SO42- and NO3- in those ranges of different alkaline metal ion content also suggested that alkaline metal ions participate in the competing neutralization reaction of sulfate and nitrate. The implication of the current study is that in some regions the chemistry to incorporate sulfur and nitrogen into particle phase might be largely affected by desert/fugitive dust and sea salt, besides NH3. This implication is particularly relevant in coastal China and those areas with strong influence of dust storm in the North China Plain (NCP), both of which host a number of megacities with deteriorating air quality. (c) 2020 Elsevier B.V. All rights reserved.

Original languageEnglish
Article number137190
Number of pages8
JournalScience of the Total Environment
Volume717
Publication statusPublished - 15-May-2020

    Keywords

  • Sulfate, Nitrate, Ammonia, Alkaline metals, SECONDARY INORGANIC AEROSOL, PEARL RIVER-DELTA, HAZE EVENTS, EVOLUTION PROCESSES, SEASONAL-VARIATION, MASS-SPECTROMETRY, SULFUR-DIOXIDE, ACIDIC GASES, AMMONIA, WATER

ID: 127605996