Source apportionment of ambient particulate matter in Kwadela, Mpumalanga
Van den Berg, Beanca
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The importance of domestic fuel burning emissions was extensively explored in this research. The aim of this research was to identify the main cause of particulate matter in Kwadela, Mpumalanga. Low income communities, such as Kwadela, are notorious for emitting particulate matter into the atmosphere, from domestic coal burning. People in poor settlements tend to use a mixture of energy carriers such as wood, coal, animal dung and paraffin. Indoor and outdoor pollution from household combustion emissions influence a large fraction of South Africa's population. Effects from these emissions are intensified in dense areas with severe health and environmental consequences. Fuel burning practices was firstly investigated on a national scale. The fuel use patterns and spatial distribution of fuel burning settlements was determined by using the South African 2011 census data. Proximity analyses on the variables that affected fuel choice were undertaken by means of Geographic Information Systems. Statistical R-square calculations were conducted to demonstrate the relationship between the determining factors and the number of fuel users. From these analyses it was found that informal and traditional households can be classified as fuel burning settlements. Determinants that could classify typical fuel burning settlements were identified and the number of people and communities affected by these emissions were calculated. An upper and lower limit calculation method was applied to determine the fraction of the population that was exposed to air pollution. According to the lower limit calculations 14 199 261 people are exposed to indoor air pollution and 19 148 085 to outdoor pollution. The upper limit estimates showed that 28 398 522 people were affected by indoor air pollution 38 296 170 by outdoor pollution. The fraction of people affected by indoor and outdoor pollution was thus 54.8% and 73.9% respectively. The local domain of this study involved the characterisation of the ambient air quality in Kwadela. The air quality of two sampling periods was investigated; a winter campaign that extended from 21/07 to 29/07 and 05/08 to 12/08 (2014) as well as a summer period from 27/03 to 14/04 (2015). Fine (<2.5μm) and coarse (10μm≤adμm≥2.5μm) particles were collected using the Gent Stacked Filter Units with a PM10 cut size inlet. Each filter unit was exposed for 12 hours (06h00-18h00 and 18h00-06h00). These filters were consequently analysed for their chemical characteristics through inductively coupled plasma-mass spectrometry, X-ray fluorescence and Ion chromatic system analyses. The most abundant species found in the winter samples were sulphate, sodium, nickel and ammonium. Ambient coarse particulate matter sampled during the summer was mainly compiled of copper, sulphur, silicon and cadmium species. Gravimetric results for the winter and summer samples showed that maximum concentrations obtained in the coarse fractions were 86.6 μg/m³ (average of 25.1 μg/m³) and 64.58 μg/m³ (average of 24.68 μg/m³) respectively. The measured fine fraction had a maximum of 170.2 μg/m³ for the winter (average 42.3 μg/m³) and 22.25 μg/m³ (average of 14.81 μg/m³) during the summer campaigns. Several of these samples exceeded the national air quality standards. Higher gravimetric masses sampled during the winter can be explained by the local community's fuel combustion practices. More coal burning occurred for heating purposes due to colder ambient temperatures. Lastly, the samples were analysed using Chemical Mass Balance to apportion contributions from different sources. The thirteen sources that influenced Kwadela's air quality were identified. Residential coal combustion was the foremost polluter that contributed a total of 738.49 μg/m³ to all the samples. The other polluting sources were diesel motor vehicles with a total contribution of 116.12 μg/m³, refuse/wood combustion with 37.01 μg/m³, paved road dust with 34.68 μg/m³ and biomass burning with 31.04 μg/m³. Coal combustion was thus by far the greatest source of air pollution. Domestic fuel burning practices should therefore be controlled in order to achieve sustainable, clean air standards.