Journal of Atmospheric Chemistry

, Volume 75, Issue 3, pp 285–304 | Cite as

Size-resolved characteristics of inorganic ionic species in atmospheric aerosols at a regional background site on the South African Highveld

  • Andrew D. Venter
  • Pieter G. van ZylEmail author
  • Johan P. Beukes
  • Jan-Stefan Swartz
  • Miroslav Josipovic
  • Ville Vakkari
  • Lauri Laakso
  • Markku Kulmala


Aerosols consist of organic and inorganic species, and the composition and concentration of these species depends on their sources, chemical transformation and sinks. In this study an assessment of major inorganic ions determined in three aerosol particle size ranges collected for 1 year at Welgegund in South Africa was conducted. SO42− and ammonium (NH4+) dominated the PM1 size fraction, while SO42− and nitrate (NO3) dominated the PM1–2.5 and PM2.5–10 size fractions. SO42− had the highest contribution in the two smaller size fractions, while NO3 had the highest contribution in the PM2.5–10 size fraction. SO42− and NO3 levels were attributed to the impacts of aged air masses passing over major anthropogenic source regions. Comparison of inorganic ion concentrations to levels thereof within a source region influencing Welgegund, indicated higher levels of most species within the source region. However, the comparative ratio of SO42− was significantly lower due to SO42− being formed distant from SO2 emissions and submicron SO42− having longer atmospheric residencies. The PM at Welgegund was determined to be acidic, mainly due to high concentrations of SO42−. PM1 and PM1–2.5 fractions revealed a seasonal pattern, with higher inorganic ion concentrations measured from May to September. Higher concentrations were attributed to decreased wet removal, more pronounced inversion layers trapping pollutants, and increases in household combustion and wild fires during winter. Back trajectory analysis also revealed higher concentrations of inorganic ionic species corresponding to air mass movements over anthropogenic source regions.


Particulate matter Sulphate Nitrate Aerosol acidity Welgegund 



The financial assistance of the National Research Foundation (NRF) towards this research is hereby acknowledged. Opinions expressed and conclusions arrived at are those of the authors and are not necessarily to be attributed to the NRF. The authors would also like to acknowledge financial support by the Academy of Finland Center of Excellence program (grant no. 272041).


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Copyright information

© Springer Nature B.V. 2018

Authors and Affiliations

  • Andrew D. Venter
    • 1
  • Pieter G. van Zyl
    • 1
    Email author
  • Johan P. Beukes
    • 1
  • Jan-Stefan Swartz
    • 1
  • Miroslav Josipovic
    • 1
  • Ville Vakkari
    • 2
  • Lauri Laakso
    • 1
    • 2
  • Markku Kulmala
    • 3
  1. 1.Unit for Environmental Sciences and ManagementNorth-West UniversityPotchefstroomSouth Africa
  2. 2.Finnish Meteorological InstituteHelsinkiFinland
  3. 3.Department of PhysicsUniversity of HelsinkiHelsinkiFinland

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