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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Temporal assessment of atmospheric trace metals in the industrialised western Bushveld Complex / van Wyngaardt G.

Van Wyngaardt, Grizelda January 2011 (has links)
The presence of trace transition metal species in the atmosphere can be attributed to the emission of particulate matter into the atmosphere by anthropogenic activities, as well as from natural sources. Trace metals emitted into the atmosphere can cause adverse health–related and environmental problems. At present, limited data exists for trace metal concentrations in South Africa. In this investigation, the general aim was to determine the concentrations of trace metals in atmospheric aerosols in the industrialised western Bushveld Igneous Complex, as well as to link the presence of these species in the atmosphere to possible sources in the region. The measurement site was placed in Marikana, a small rural town situated 35 km east from Rustenburg in the North West Province of South Africa. It is surrounded by numerous industrial and metallurgical operations. MiniVolumeTM samplers and Teflon® filters (2 ;m pores) were utilised to collect PM2.5 and PM10 particulate samples. The MiniVolumeTM samplers were programmed to filter 5 litres of air per minute for 12 hours per day, over a six–day period. The starting time for sampling was altered every six days, in order to obtain both day and night samples. Sampling was performed for a period of one year. The collected samples were chemically analysed with inductively coupled plasma mass spectroscopy (ICP–MS). Surface analysis of the sampled filters was performed with a scanning electron microscope (SEM) in conjunction with energy–dispersive spectroscopy (EDS). The dataset was also subjected to factor analysis in an attempt to identify possible sources of trace metal species in the atmosphere. The concentrations of 27 trace metals (Be, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Pd, Cd, Ba, Pt, Au, Hg, Tl, Pb, U) were determined. Pd, Hg, Tl, U, Ca, Co, As, Cd, Ba and Au were above the detection limit 25% or less of the time during the sampling period. With the exception of Ni, none of the trace metals measured at Marikana during the sampling period exceeded local and international standards. Higher Ni levels were possibly due to base metal refining in the region. Pb, which is the only metal species that has a standard prescribed by the South African Department of Environmental Affairs (DEA), did not exceed any of the standards. It is also significant to refer to Hg that was below the detection limit of the analytical instrument for the entire sampling period. The impact of meteorological conditions revealed that wet removal of atmospheric PM10 trace metals was more significant than the wind generation thereof. During the dry months, the total trace metal concentrations in the PM10 fraction peaked, while PM10 particles were mostly washed out during the wet season. Wind speed showed an unexpected inverse pattern compared to wet deposition. A less significant seasonal trend was observed for the trace metal concentrations in the PM2.5 fraction, which was attributed to a faster replenishment of smaller particles into the atmosphere after rain events. Separation of trace metal concentrations into PM10–2.5 and PM2.5 fractions indicated that 79% of the total trace metal levels that were measured were in the PM2.5 fraction, which indicated a strong influence of industrial and/or combustion sources. Fractionalisation of each of the trace metal species detected showed that for each metal species, 40% and more of a specific metal was in the PM2.5 fraction, with Cr, V, Ni, Zn and Mn occurring almost completely in the PM2.5 fraction. Surface analysis with SEM supported results from the chemical analysis, which indicated that a large fraction of the particles was likely to originate from anthropogenic activities and from wind–blown dust. SEM–EDS also detected nonmetallic S that is usually associated with the Pt pyrometallurgical industry that is present in the western Bushveld Igneous Complex. Correlations between Cr, V, Ni, Zn and Mn revealed that the main sources of these species were pyrometallurgical industries. Explorative factor analysis of the unprocessed and Box–Cox transformed data for all 27 metals detected, resolved four meaningful emission sources, i.e. crustal, vanadium related, base metal related and chromium related. Comparison of trace metal species to other parameters measured (e.g. CO, BC) also indicated pyrometallurgical activities and wind–blown dust to be the main sources of trace metals in this region. / Thesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2011.
2

Temporal assessment of atmospheric trace metals in the industrialised western Bushveld Complex / van Wyngaardt G.

Van Wyngaardt, Grizelda January 2011 (has links)
The presence of trace transition metal species in the atmosphere can be attributed to the emission of particulate matter into the atmosphere by anthropogenic activities, as well as from natural sources. Trace metals emitted into the atmosphere can cause adverse health–related and environmental problems. At present, limited data exists for trace metal concentrations in South Africa. In this investigation, the general aim was to determine the concentrations of trace metals in atmospheric aerosols in the industrialised western Bushveld Igneous Complex, as well as to link the presence of these species in the atmosphere to possible sources in the region. The measurement site was placed in Marikana, a small rural town situated 35 km east from Rustenburg in the North West Province of South Africa. It is surrounded by numerous industrial and metallurgical operations. MiniVolumeTM samplers and Teflon® filters (2 ;m pores) were utilised to collect PM2.5 and PM10 particulate samples. The MiniVolumeTM samplers were programmed to filter 5 litres of air per minute for 12 hours per day, over a six–day period. The starting time for sampling was altered every six days, in order to obtain both day and night samples. Sampling was performed for a period of one year. The collected samples were chemically analysed with inductively coupled plasma mass spectroscopy (ICP–MS). Surface analysis of the sampled filters was performed with a scanning electron microscope (SEM) in conjunction with energy–dispersive spectroscopy (EDS). The dataset was also subjected to factor analysis in an attempt to identify possible sources of trace metal species in the atmosphere. The concentrations of 27 trace metals (Be, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Pd, Cd, Ba, Pt, Au, Hg, Tl, Pb, U) were determined. Pd, Hg, Tl, U, Ca, Co, As, Cd, Ba and Au were above the detection limit 25% or less of the time during the sampling period. With the exception of Ni, none of the trace metals measured at Marikana during the sampling period exceeded local and international standards. Higher Ni levels were possibly due to base metal refining in the region. Pb, which is the only metal species that has a standard prescribed by the South African Department of Environmental Affairs (DEA), did not exceed any of the standards. It is also significant to refer to Hg that was below the detection limit of the analytical instrument for the entire sampling period. The impact of meteorological conditions revealed that wet removal of atmospheric PM10 trace metals was more significant than the wind generation thereof. During the dry months, the total trace metal concentrations in the PM10 fraction peaked, while PM10 particles were mostly washed out during the wet season. Wind speed showed an unexpected inverse pattern compared to wet deposition. A less significant seasonal trend was observed for the trace metal concentrations in the PM2.5 fraction, which was attributed to a faster replenishment of smaller particles into the atmosphere after rain events. Separation of trace metal concentrations into PM10–2.5 and PM2.5 fractions indicated that 79% of the total trace metal levels that were measured were in the PM2.5 fraction, which indicated a strong influence of industrial and/or combustion sources. Fractionalisation of each of the trace metal species detected showed that for each metal species, 40% and more of a specific metal was in the PM2.5 fraction, with Cr, V, Ni, Zn and Mn occurring almost completely in the PM2.5 fraction. Surface analysis with SEM supported results from the chemical analysis, which indicated that a large fraction of the particles was likely to originate from anthropogenic activities and from wind–blown dust. SEM–EDS also detected nonmetallic S that is usually associated with the Pt pyrometallurgical industry that is present in the western Bushveld Igneous Complex. Correlations between Cr, V, Ni, Zn and Mn revealed that the main sources of these species were pyrometallurgical industries. Explorative factor analysis of the unprocessed and Box–Cox transformed data for all 27 metals detected, resolved four meaningful emission sources, i.e. crustal, vanadium related, base metal related and chromium related. Comparison of trace metal species to other parameters measured (e.g. CO, BC) also indicated pyrometallurgical activities and wind–blown dust to be the main sources of trace metals in this region. / Thesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2011.
3

School choral eisteddfodau in the Polokwane Cluster of circuits in the Capricorn District of Limpopo Province, South Africa : an assessment of racial participation

Mashamaite, Duke Matome David January 2014 (has links)
This research project was sparked by the observed patterns of participation in the schools choral eisteddfodau organised by the South African Schools Choral Eisteddfod (SASCE) and the Bosveld Kunstefees by schools in the Polokwane cluster of Circuits, Capricorn District of Limpopo Province - South Africa. The projected image of participation was that participation was divided along racial lines, whereby SASCE events were attended by blacks, found at township and rural schools, whereas former Model C schools attended the Bosveld Kunstefees eisteddfodau. The study intended to reveal whether the projected racial image was founded on racism itself, after 20 years the democratic dispensation, or whether other factors such as choral aptitude, preference of choral style, and/or cultural identity in a pluralistic society influenced such participation. Data were collected and qualitatively analysed by means of a structured questionnaire administered to school principals, choir masters/mistresses and secondary school choristers whose schools participated in either of the eisteddfodau between 2009 and 2011. Findings and recommendations are then offered for the research questions asked, following the analysis of collected data. / Dissertation (MMus)--University of Pretoria, 2014. / lk2014 / Music / MMus / Unrestricted

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