Verification of gas pollutants from selected ground-based monitoring stations in Limpopo

This thesis investigated the accurate baseline gas pollution levels in Polokwane, Phalaborwa, Lephalale and Steelpoort by verifying gas pollutants concentrations as monitored by ground-based monitoring stations. Active and passive sampling of SO2, NOx together with benzene, toluene, ethylbenzene and xylene (BTEX) was used throughout the year in 2021. For BTEX measurement, gas chromatography coupled with flame ionization detection was employed, while ion chromatography was applied for the analysis of SO2 and NO2. The relationship between air pollutants and meteorological variables (temperature, humidity, wind speed, and solar radiation) sourced from the South African Air Quality Information System was analysed statistically with IBM SPSS. Version 10. In all places under study, SO2 concentrations are high during the winter. Steelpoort has the highest SO2 levels, followed by Lephalale, Polokwane, and Phalaborwa. Compared to Phalaborwa, Polokwane, and Steelpoort, Lephalale had the highest NO2 values. The NO2 concentration was lower than the annual limit recommended by World Health Organization (WHO),10 μg/m3. Additionally, the concentrations of SO2 were lower than National ambient air quality standards (NAAQS) (50 μg/m3). Toluene was determined to be the most prevalent BTEX among the concentrations examined. While xylene levels were high in the spring, ethylbenzene was not detectable at all stations, wintertime saw the highest quantities of benzene and toluene. The highest concentrations observed were 0.69 μg/m3, 2.97 μg/m3 and 0.80 μg/m3 for benzene, toluene and xylene, respectively. All concentrations were under the standards set by NAAQS, which is 5 μg/m3, and by WHO guidelines, namely, 260 μg/m3, 870 μg/m3 and 290 μg/m3, for benzene, toluene, xylene and ethylbenzene, respectively. The ratios of toluene to benzene show that both industrial processes and automobile emissions release volatile organic compounds. Temperature, wind speed, and relative humidity are examples of meteorological variables that affect dispersion of NO2 and SO2. Furthermore, there is a positive and negative association between BTEX and certain meteorological parameters. Although SO2, NO2, and BTEX concentrations are low in the investigated area, these pollutants must be continuously monitored to prevent any health hazards. KEY WORDS: Monitoring stations, Gas pollution, Pollutants concentrations, SO2, NO2, Benzene, Toluene, Ethylbenzene, Xylene, Meteorological factors, Correlation.

Ph.D. (Environmental Science)

Environmental Sciences