Abstract

WALTON, Nicola M. et al. Source apportionment of ambient fine and coarse aerosols in Embalenhle and Kinross, South Africa. Clean Air J. [online]. 2021, vol.31, n.2, pp.1-13. ISSN 2410-972X.  http://dx.doi.org/10.17159/caj/2020/31/2.11980.

The South African Highveld is recognised as a region having significant negative ambient air quality impacts with its declaration as an Air Quality Priority Area in 2007. Such areas require the implementation of specific air quality intervention strategies to address the air quality situation. A greater understanding of the composition of the atmospheric aerosol loading and the contributing air pollution sources will assist with the formulation and implementation of these strategies. This study aims to assess the composition and sources of the aerosol loading in Embalenhle and Kinross located on the Highveld. Fine (PM_2.5) and coarse (PM._25-10) aerosol samples were collected during summer and winter, which were quantified by gravimetry. Wavelength-Dispersive X-Ray Fluorescence (WD-XRF) spectrometry and Ion Chromatography (IC) analysis were applied to determine the chemical compositions of aerosol samples on filters. Mean PM_2.5 concentrations in Embalenhle and Kinross ranged from 16.3 to 34.1 ug/m³ during winter and 7.4 to 19.0 ug/m³ during summer. Mean PM_2.5-10 concentrations ranged from 10.3 to 114 ug/m³ during winter and 5.9 to 11.2 μg/m³ during summer. Si, Al, S, SO₄^2- and NH₄+ were the most abundant species in PM_2.5 during both seasons. The elements Na and Ca were also abundant at both sites during winter and summer, respectively. In PM_2.5-10, Si, Al, SO₄^2- and F^- were the most abundant species during both seasons. The element Na was also abundant at both sites during winter with S and Ca also having high abundances at Embalenhle and Kinross, respectively, during summer. Source apportionment was performed by Positive Matrix Factorisation (PMF), which resolved five sources. Dust, secondary aerosols, residential combustion, wood and biomass burning, and industry were determined to be the contributing sources. Any measures to mitigate particulate air pollution on the Highveld should consider these key sources.

Keywords : Particulate matter; source apportionment; positive matrix factorisation; backward trajectories.

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