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A white clover ( Trifolium repens ) system, based on one ozone-sensitive (NC-S) and one ozone-resistant (NC-R) clone, has been developed as an indicator to estimate the effects of tropospheric ozone on plant biomass production. A reduction in the vegetative biomass ratio (NC-S/NC-R) of the clones was correlated with increasing concentrations of ozone during a 28-day exposure period. However, the mechanism of ozone sensitivity or tolerance at the biochemical or molecular level is not known. Superoxide dismutase isozyme activities in the two clones did not respond differently to ozone treatment. However, catalase activity increased somewhat more in the leaf tissue of NC-R, compared to NC-S, after ozone treatment. Two-dimensional polyacrylamide gel electrophoresis (PAGE) showed the presence of two proteins (Ozone-Response-Proteins, ORPs) that were more responsive to ozone in the tolerant genotype than in the sensitive one. After ozone treatment for three days, the ORPs were four-fold higher in leaf tissue of NC-R compared to NC-S. Also, the amount of the ORPs was twenty-fold higher in leaf tissue of ozone-treated NC-R than in that of control NC-R. These proteins have apparent molecular weights of 21.5 kD and 23 kD and isoelectric points of 4.1-4.4 on SDS-PAGE gels. The filtrate of a 100 kD concentrator showed that the native molecular weights of the ORPs were less than 100 kD. The results obtained from a study of field samples demonstrated that protein content in leaf tissue of both NC-R and NC-S was positively correlated with ORP content. / Master of Science

Ozone is a powerful oxidant and disinfectant used in potable wastewater reuse to destroy specific harmful compounds, including pharmaceuticals, personal care products and endocrine disrupting compounds. Ozonation also increases the biodegradability of recalcitrant organic compounds and inactivates disease-causing microbes. However, bromate, a regulated possible human carcinogen can form when bromide is present due to natural or industrial sources. Pilot-scale testing on wastewater treatment plant effluent with high bromide concentrations showed that the addition of preformed monochloramine could reduce bromate formation by as much as 97%. Monochloramine addition was able to keep concentrations below the U.S. Environmental Protection Agency Maximum Contaminant Level of 10 µg/L while exceeding 3-log or 99.9% virus removal credit. Preforming monochloramine in separate carrier water prior to addition upstream of ozonation eliminated the potential for disinfection byproduct formation when monochloramine is formed in the main water flow. This also allowed for the mechanisms of bromate suppression by monochloramine to be examined without the influence of reactions between chlorine and dissolved organic matter present. This research can help increase the application of ozonation in water reuse. / MS / Ozone is a powerful oxidant and disinfectant used in potable wastewater reuse to destroy specific harmful compounds, including pharmaceuticals, personal care products and endocrine disrupting compounds. Ozonation also increases the biodegradability of recalcitrant organic compounds and inactivates disease-causing microbes. However, bromate, a regulated possible human carcinogen can form when bromide is present due to natural or industrial sources. Pilot-scale testing on wastewater treatment plant effluent with high bromide concentrations showed that the addition of preformed monochloramine could reduce bromate formation by as much as 97%. Monochloramine addition was able to keep concentrations below the U.S. Environmental Protection Agency Maximum Contaminant Level of 10 µg/L while exceeding 3-log or 99.9% virus removal credit. Preforming monochloramine in separate carrier water prior to addition upstream of ozonation eliminated the potential for disinfection byproduct formation when monochloramine is formed in the main water flow. This also allowed for the mechanisms of bromate suppression by monochloramine to be examined without the influence of reactions between chlorine and dissolved organic matter present. This research can help increase the application of ozonation in water reuse.

Measurements of surface ozone in Durban have been undertaken since September 1994 until August 1995 using a Dasibi ozone monitor model 1108. There is a seasonal variation in surface ozone with a small amplitude of 6.5 ppb. The mean maximum of 12.5 ppb is experienced in August and the minimum in December (6 ppb). The late winter peak and the sharp rise from June to July is possibly related to the greater accumulation of ozone at the surface due to the poor dispersion, higher frequency of inversions and lower mixing depth. The study also focuses on the relationship between synoptic weather systems and daily ozone concentrations in an attempt to establish if any relationship exists. The analysis suggests that there is an increase in ozone concentration during the pre-frontal and established high pressure systems and a reduction in ozone under postfrontal conditions. The mean diurnal variation in surface ozone depicts a maximum between solar noon and 14:00, which is typical of an urban-industrial environment, in which ozone precursor gases have built up during the morning. However, a secondary peak in the early morning during winter and autumn was more difficult to explain and is thought to be due to the transport of ozone from the interior in the mountain-plain wind systems. Comparison of ozone values at Durban with results available from the other locations in South Africa such as Cape Point and the Eastern Transvaal Highveld has been undertaken. Ozone values at Durban are lower than Cape Point, which is a representative of a background monitoring station. It ls hypothesised that those low ozone concentrations may be due to high NOx which in turn depletes ozone. / Thesis (M.Sc.)-University of Natal, 1995.

The main purpose of this thesis is to empirically calculate the welfare changes which might be expected to result from potato yield reductions caused by ambient ozone loadings in the Lower Mainland of British Columbia. The objectives of the research are: (1) to review the scientific literature pertaining to the effects of ozone loadings on agricultural crops; (2) to review the methodologies employed in previous regional economic assessments of ozone damages; and (3) to apply an economically defensible technique to the analysis of welfare losses due to ozone. Ozone in the Lower Mainland may be pictured as being restricted laterally by the mountain ranges surrounding Vancouver, and vertically by stagnant high pressure systems. Land/sea breezes aid in transporting ozone and its precursors from Vancouver up the Fraser Valley towards important crop growing regions. The highest levels of ozone occur during spring and summer coinciding with the most active season for many crops. Seasonal ambient ozone dose, measured as hours-ppm>0.10ppm was found to be high in rural areas, especially Abbotsford, during the late 1970's and early 1980's, dropping to low levels in more recent years. Potatoes are one of the economically important crops in the Lower Mainland known to be sensitive to ozone. Potato tuber weight reductions are estimated to have reached 16.5 percent in the Abbotsford region in 1981 at seasonal ambient ozone loadings. An aggregate supply/demand model is set up for potato production in B.C. based upon prior estimates of supply and demand elasticities. This model assumes the price in the B.C. market is set exogeneously by U.S. imports. Thus, all policy relevent welfare changes affect producers' quasi-rent alone. Sensitivity of the model to import price, and the price elasticity of supply is tested. A range of welfare estimates is reported for a variety of ambient ozone loadings. The total damages to potato producers, assuming all regions of B.C. are affected by the same seasonal dose as Abbotsford, are calculated to be around one million dollars at ambient ozone loadings in four out of eight years. A peak occurred in 1981 at 2.4-2.9 million dollars total damages. Damages may be overestimated because 20-30 percent of potato production takes place outside the Lower Mainland, Abbotsford often appears to receive higher ambient ozone loadings than other regions, and not all potato cultivars grown in the Lower Mainland are as sensitive to ozone as that employed here. However, there are also reasons to be cautious over discounting these estimates as too large. Potato response to ozone is restricted to tuber weight reductions while other important effects may include increased plant stress and damage to crop quality. In addition, missing air quality information for some years and stations, suggests that actual ozone dose could be higher than calculated. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate

Measurements by the TOMS instrument aboard the Nimbus 7 satellite, of total column ozone over polar regions have been studied to determine the effects of solar induced natural ozone modulation. Two different analysis methods were employed to ascertain short term (days to months) and long term (months to years) solar influences on polar ozone. Bursts of intense solar activity can result in solar proton events (SPE's). The high energy protons, originating in solar flares, produce secondary electrons which can generate large concentrations of odd nitrogen in the middle atmosphere. These reactive species can catalytically destroy ozone. Three case studies are presented in an attempt to quantify the effect of SPE's on ozone mass over a latitude region 90 to 70°. In order to monitor the ozone response following a SPE over both hemispheres simultaneously, the SPE must occur during the equinox period when both poles are irradiated. Fortuitously, a SPE was recorded in March 1989, the analysis of which forms a case study in this thesis. Ozone depletions of 7.4 x 10 to the power of 9 kg for the south polar cap and 8.0 x 10 to the power of 9 kg for the north polar cap indicate the degree of symmetry for this event. Longer term effects of solar variability are investigated by Fourier techniques. A Fourier transform of eleven years of total ozone mass values, over the region 90 to 70° S, was performed. Inspection of the Fourier spectrum reveals peaks associated with solar cycle, annual and semi-annual oscillations, that may be attributed directly to solar variation. Other peaks, corresponding to QBO and ENSO periodicities, may be ascribed to indirect solar influences i.e. thermally driven dynamics. Finally, a comparison between the phase of the solar cycle peak in this spectrum with that in a spectrum of daily values of solar radio flux, reveals that the austral polar ozone solar cycle periodicity lags solar forcing by 2.8 years. Portions of chapters have been reported at the 1990 South African Institute of Physics Annual Conference, University of Port Elizabeth, South Africa and as a poster at the 1992 Quadrennial Ozone Symposium, Charlottesville, United States of America, 4-13 June 1992. In addition, various parts of this work has been submitted for publication, viz: Stephenson, J. A. E. and M. W. J. Scourfield, Importance of energetic solar protons in ozone depletion, Nature, 352, 137: 1991. / Thesis (Ph.D.)-University of Natal, Durban, 1994.

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While the market for “green” building materials has been expanding rapidly, no rigorous framework exists for evaluating the chemical and biological reactivity of these building materials. The objective of this research was to assess the ozone reactivity, primary and secondary VOC emission rates and mold resistance of selected green building materials. Two different sets of experiments were conducted. The first set focused on reactive consumption of ozone by ten common green materials. A screening assessment of secondary emissions of C6 and greater carbonyls was also completed for selected green materials. The second set was completed to evaluate the relative resistance of selected green building materials and their conventional analogs to surface fungal growth in moist interior environments. Ozone reactivity varied considerably between test materials. The ozone deposition velocity for inorganic ceiling tiles, for example, was two times higher than cabinetry materials and approximately fifty times higher than UV-coated bamboo. Experimental results were used as input to a simple mass balance model which predicted that the ratio of indoor to outdoor ozone concentrations was not significantly affected by green building materials. The green materials used in this study emitted less primary and secondary VOCs than did their non-green counterparts, although the difference was not significant and the material sample set was relatively small. Also, the green materials tested were not prone to either less or more mold growth than their conventional counterparts. Instead, materials composed of organic materials with high equilibrium moisture contents (EMC) were more prone to mold growth than inorganic materials with low EMC. Perlite-based (inorganic) ceiling tiles that consumed relatively large amounts of ozone without corresponding by-product formation were also resistant to mold growth. Such findings should facilitate the selection of future green building materials, both explicitly and by defining a protocol for future testing of green materials. / text

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