Source apportionment of fine atmospheric particles using positive matrix factorization in Pretoria, South Africa

• In Pretoria South Africa, we looked into the origins of fine particulate matter (PM2.5), based on one-year sampling campaign carried out between 18 April 2017 to 17 April 2018. The average PM2.5 concentration was 21.1± 15.0 µg/m3 (range 0.7 - 66.8 µg/m3), with winter being the highest and summer being the lowest. The XEPOS 5 Energy dispersive X-ray fluorescence (EDXRF) spectroscopy was used for elemental analysis, and the US EPA PMF 5.0 program was used for source apportionment. The sources identified includes fossil fuel combustion, soil dust, secondary sulphur, vehicle exhaust, road traffic, base metal/pyrometallurgical, coal burning. Coal burning and secondary sulphur were significantly higher in winter and contributed more than 50% of PM2.5 sources. The HYSPLIT model was used to calculate the air mass trajectories (version 4.9). During the one-year research cycle, five transportation clusters were established. North Limpopo (NLP), Eastern Inland (EI), Short-Indian Ocean (SIO), Long-Indian Ocean (LIO) and South Westerly-Atlantic Ocean (SWA). Local and transboundary origin accounted for 85%, while 15% were long-range transport. Due to various anthropogenic activities such as biomass burning and coal mining, NLP clusters were the key source of emissions adding to the city's PM rate. In Pretoria, the main possible source regions of PM2.5 were discovered to be NLP and EI. Effective control strategies designed at reducing secondary sulphur, coal burning, and fossil fuel combustion emissions at Southern African level and local combustion sources would be an important measure to combat the reduction of ambient PM2.5 pollution in Pretoria.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

Nyckelord

Air pollution

Source apportionment

Particulate matter

Biomass burning

Transport cluster

South Africa

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