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The distribution of aerosol and trace gases in the lower troposphere over South AfricaBurger, Roelof Petrus January 2016 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy.
September 2016. / Numerous studies on the sources, transport and fates of criteria air pollutants and greenhouse
gases have been done in southern Africa. However, debate on the priority pollutants and areas
of concern continue despite a growing national air quality monitoring network. This study
attempts a novel approach to characterise sources and ambient air quality over major industrial
and urban areas using a single suite of instrumentation to provide information to improve
management of air quality. Over 200 hours of data were collected from an airborne platform.
Another 5 ground-based campaigns characterised sources and areas out of reach of the aircraft.
The central aim of this study is to prioritise sources and areas of concern with regards to air
quality management, using a mobile platform. This complements other modelling and spatial
assessments and provides in situ validation for many contemporary debates. The specific aims
were to characterise major anthropogenic sources; estimate the state of air quality; investigate
the vertical distribution of pollutants; and prioritise sources and areas of concern for effective
air quality management in South Africa.
The research has delivered many original contributions to the body of knowledge of air quality
over South Africa. These findings can be divided into spatial and temporal relationships
between sources and receptors, characterising source contributions and understanding the contribution
of atmospheric emissions. High resolution measurements show that spatial scales of
prominent atmospheric plumes are much smaller than current remote sensing estimates.This
underscores the difficulty of accurately assessing environments with diverse, clustered sources
and complex meteorology through modelling studies and satellite based remote sensing.
The current conceptual model of absolute stable layers is biased because of limited data availability
where a limited number of levels are reported. At least 60 levels should be reported
in soundings to study absolutely stable layers. The inclusion of the standard reporting levels,
(850 hPa, 700 hPa, 500 hPa and 300 hPa), further biases the detection of atmospheric stable
layers. The number of observed persistent levels change in number and character when these
are omitted from the analysis. Numerous vertical profiles further show that the thermodynamic
model of stability as the main driver of stratification is oversimplified, especially close
to source regions where different pollutants are observed to peak at different levels unrelated
to absolutely stable layers. This suggests that the original buoyancy which is governed by
the release temperature, exit velocity and height are important drivers for the stratification of
pollutants.
The overall conclusion is made that a small team with a set of regular instrumentation can
prioritise pollutants and areas of concern on a national scale. This method could be valuable
for countries with limited resources and infrastructures and could be used in combination with
modelling and satellite based remote sensing to assess priorities. The ability to obtain in situ
data of a large number of variables over vast areas in a short time may offsets the caveats
associated with mobile measurements and a limited sample volume. / LG2017
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Airborne DOAS measurements over the South African highveldBroccardo, Stephen Paul January 2015 (has links)
A thesis submitted to the Faculty of Geography, Archaeology, and Environmental Studies University of the Witwatersrand, Johannesburg, in fulfilment of the requirements of the degree of Doctor of Philosophy. 2015. / An imaging DOAS instrument, along with in situ trace-gas and aerosol instrumentation
was deployed on board a research aircraft over the Highveld
region of South Africa, to make regional-scale measurements of nitrogen dioxide
(NO2). The presence of a “hotspot” of NO2 over the Highveld is confirmed.
Case-study estimates of NO2 emission flux were made downwind of
a power station (10 tons.hr−1), a petrochemical plant (36 tons.hr−1) and the
entire Highveld region (395 tons.hr−1).
Vertical profile measurements were used to develop scenarios for a radiative
transfer sensitivity study. From this, suitable air-mass factors for the DOAS
measurements were determined. Comparisons between the airborne DOAS
and satellite instruments show a good agreement where the spatial scales of
the satellite ground pixels and the features in the two-dimensional trace-gas
distribution are matched.
A long-term record of satellite data was analysed. Analysis of radiative
transfer revealed a possible artefact in the adjacent positive and negative
trends evident on the Highveld. A correction to the satellite record for a
seasonal bias was made, and found to be important over biomass burning
regions in Angola and Zambia.
Spatial features in a seasonal model of the satellite record are shown to
correspond with known urban, industrial and biomass burning sources in the
region. Signatures of soil emissions are also detected.
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Concentration distributions of non-buoyant, weakly buoyant and buoyant effluents from a continuous point source within a convectively mixed layerGurer, Kemal 21 April 1987 (has links)
Graduation date: 1987
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Design and application of ion selective electrodes in atmospheric pollution analysisKneebone, Barbara Maria Nowicki, 1948- January 1972 (has links)
No description available.
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Activation analysis of airborne particulatesLongley-Cook, Barbara Ann Norman, 1942- January 1969 (has links)
No description available.
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A microwave spectroscopic technique in the measure of pollutant sulfur dioxide in the atmosphereBeren, Jeffrey Allen, 1946- January 1972 (has links)
No description available.
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The utility of using matched weight PVC filters during air sampling for particulatesNordstrom, Jeanne McDonald, 1957- January 1988 (has links)
Matched weight polyvinyl chloride (PVC) filters are currently available for use in total dust air sampling. This paper studies the utility of employing two superimposed filters in a cassette. Cassettes containing "paired" PVC filters were employed, in the same way matched weight filters would be used, during side by side sampling studies with cassettes housing single PVC filters, to determine whether the presence of two filters in a cassette presented problems during sampling. The effects of dust type, particle breakthrough, moisture concentration, and increased pressure drop from the addition of a second filter were studied. The presence of static electricity between filter pairs was also noted. Under recommended loading conditions "paired" filters seemed to perform as well as single filters in all aspects studied. Due to large filter weight variations found within individual batches of PVC filters, randomly selected filter pairs should not be used as actual matched weight filters.
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PRELIMINARY EVALUATION OF THE ENVIRONMENTAL CONCENTRATION AND TOXICITY OF 4-PHENYLCYCLOHEXENE: AN EMISSION OF NEW CARPETING (ODOR, HEALTH, INDOOR)Walsh, Dale Warner, 1961- January 1986 (has links)
No description available.
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A timed exposure diffusive sampler for air monitoring in epidemiologyMichaud, Jon-Pierre, 1955- January 1989 (has links)
A timed exposure diffusive sampler (TEDS) sensitive enough to measure hourly averages of nitrogen dioxide (NO2) at low parts per billion levels was developed for use in epidemiological studies. TEDS can be used for a variety of atmospheric pollutants. TEDS was tested in the laboratory against known concentrations of NO2 and against well established NO2 measurement systems. It was then tested in the field against the Environmental Protection Agency's reference method for measuring NO2. The TEDS method appears well suited to epidemiological investigations of air quality and extends previous work in this area by offering improved time resolution of changes in pollutant concentration at a cost sufficiently low to permit its use in large scale studies. The TEDS method also shows potential for miniaturization for use in personal sampling.
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An absolute method for aerosol particle mass measurementPhilip, Mark Andrew January 1982 (has links)
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Mark Andrew Philip. / M.S.
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