No description available.

A project was conducted to determine the relative effectiveness of several antichlors in regards to their Cl₂ and ClO₂ gaseous "scrubbing" capacity. Both a pilot study as well as full scale trials were completed. Work was done on a bleach plant-packed tower scrubber system at a kraft pulp and paper mill. The pilot study was performed at pH's of 10.0 to 12.0 and therefore may have masked the scrubbing potential of two, lower pH, antichlors. Results from the full-scale trials showed that 45% Sodium Hydrosulfide (NaHS) solution, was the most efficient when compared to 42% Sodium Bisulfite (NaHSO₃) solution and CoProduct solution. A cost analysis was completed and revealed that CoProduct solution was the most cost effective of the three compounds. Other non-economic factors such as scrubber plugging tendencies, the potential for toxic gas formation, and handling difficulties should be examined before a final choice of antichlors is made. / M.S.

This research investigated emissions of formaldehyde, acetaldehyde, carbon monoxide, and hydrocarbons from a small utility engine fueled with mixtures of gasoline, ethanol, and methanol. Measurements made for each fuel mixture, with and without a catalyst, allowed a qualitative evaluation of the catalyst effect on the aforementioned pollutants. California Air Resources Board small utility engine regulations motivated this research. The engine was loaded by an electrical generator with output of approximately 1000 watts to simulate actual operating conditions. Operation occurred at steady state conditions with a fixed air/fuel ratio. Alcohol addition reduced emissions of carbon monoxide (CO) and total hydrocarbons (THC) from gasoline only levels. Adding a 50% volume of ethanol to the fuel, CO and THC emissions decreased 75% and 50% respectively. Adding 50% methanol reduced CO and THC 95% and 60% respectively. Qualitatively, no catalytic control of CO or THC was demonstrated with any of the fuels used. However, a lack of replicates prevented quantification of catalyst results. Both formaldehyde and acetaldehyde emissions increased with the addition of ethanol. Addition of 50% ethanol resulted in an increase of at least 600% in acetaldehyde emissions. Methanol addition increased formaldehyde emissions, but correlation of emissions with alcohol content was not possible. Acetaldehyde emissions appeared to decrease with increasing methanol content after an initial increase from the gasoline only values. No catalytic oxidation of formaldehyde was demonstrated, but acetaldehyde emissions may have been decreased by the catalyst when employing 50% ethanol fuel. / Master of Science

No description available.

published_or_final_version / Community Medicine / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

The focus of my research is to apply stable isotopes as a new tool to understand free radical chemistry in the troposphere. Stable carbon isotope ratios are used as indirect tracers of the reaction of nonmethane hydrocarbons (NMHC) with OH radicals in ambient air from Toronto and Vancouver air-sheds, Canada. Compound-specific stable carbon isotope ratios of NMHC were determined in ambient air from urban, suburban, rural and source sites in the air-sheds using Gas Chromotograph-Isotope Ratio Mass Spectrometry (GC-IRMS). In the Greater Toronto Area, the average isotope ratio of all ambient measurements of NMHC, including halogenate NMHC was found to be -25.7 + 3.4 %o. Traffics related source sites in the Greater Toronto Area have an average isotope ratio of -25.7 + 3.5 %o, whereas the ratio for traffic related emissions in the Lower Fraser Valley are -25.9 + 4.2 %o. The extent of chemical processing due to OH radical reactions that the individual NMHC has experienced since emission is quantitatively determined. It is shown that in combination with concentration measurements, isotope ratio measurements are an extremely valuable new approach to study the spatial and temporal differences in chemical removal mechanisms, mixing and dilution processes.

Thesis (MTech (Environmental Management))--Cape Peninsula University of Technology, 2015. / The integrity of natural air has been compromised due to the deposition of chemical, biological and particulate substances from natural and anthropogenic sources. Adverse health consequences arising from the exposure of plants, animals and human to elevated atmospheric concentrations have been reported severally. The ambient baseline levels of many air contaminants in urban and industrial layouts of many Africa cities, especially Zimbabwe have not been fully characterized. Information on levels of these contaminants and their real time variability is therefore scarce and scanty. In this study, the ambient air concentration levels of selected gaseous pollutants in the vicinity of a fertilizer production facility in Zimbabwe were investigated. Nine sampling stations were systematically and randomly identified for the measurement of selected air pollutants (SO2, NO2, and NH3) the fertilizer production factory to capture air quality data on all wind directions. The electrochemical Drager Sensors which rely on electrochemical measuring transducer for measuring concentration of gases under atmospheric conditions was used for the measurement of NH3, SO2, and NO2. The ambient air monitored was allowed to diffuse through a membrane into the sensor liquid electrolytes, containing a sensing electrode, a counter electrode, a reference electrode, and an electronic potentiostat-circuit which ensures constant electrical voltage between the sensing electrode and the reference electrode. The flow of electrons, generated by the reaction is proportional to the concentration of the measured gas. The observed concentrations of NH3, SO2, and NO2 measured within and around the study site were very variable. Levels of NH3 ranged between 0.36 - 7.36 ppm; corresponding values for SO2 and NO2 were 0.02 - 84.61 ppm and 0.61 - 34.78 ppm respectively. These concentrations were significantly higher (p < 0.05) than measured (NH3; 0.01 - 0.05 ppm: SO2; 0.03 - 0.18 ppm: NO2; 0.17 - 1.30 ppm) at the control sampling station about 5 km from the industry. Isokinetic and dissipation of the measured gases, governed by the processes of molecular diffusion and convection, confirmed a common pattern of distance dissipation. Thus, the cloud concentrations of NH3, SO2, and NO2 within the facility were higher than observed distances away from the fertilizer factory. / Zimbabwe Presidential Scholarship

第三人效果研究已經過三十餘年的發展，但比較第三人效果認知對於行為層面預測力的研究仍然相當有限。本研究以霧霾調查紀錄片《穹頂之下》為研究主題，從心理學利己、利他動機的視角出發，探討第三人效果認知層面與行為層面間的關係。本研究在上海、深圳兩地進行問卷調查，共訪問926名大學生，研究結果顯示，受訪者會傾向於認為環保資訊對他人產生的影響大於對其自身產生的影響；然而，本研究發現，「對自己影響的認知」比「對他人影響的認知」更能顯著預測受訪者的蒐集資訊與響應性行為。同時，本研究結果顯示，「議題與個人的關聯程度」、「對訊息的涉入程度」均會影響「對自己影響的認知」和「對他人影響的認知」對行為意願的預測力。這些研究發現對於豐富第三人效果的理論框架有一定貢獻，同時亦為環境保護資訊的傳播提供了一定的實踐啟示。 / The third-person effect (TPE) hypothesis has been developed for over 30 years. However, very limit amount of TPE research have focus on comparing the predictive power of "perceived influence on self" and "perceived influence on others". This research fills the research gap by examining the relation between perceptual and behavioral components in the context of a Chinese documentary concerning haze weather, Under the Dome. Using the data from a survey concerning public opinion towards the haze documentary involving a sample of 939 college students in Shanghai and Shenzhen, results indicate that respondents tend to perceive the haze documentary have a larger influence on others than on themselves regardless of their perceived desirability of the documentary, and the perceived influence on self is a better predictor of the behavioral component compared to the perceived influence on self. Furthermore, issue relevance and media message involvement both have an influence on the predictive power of perceived influence on self and perceived influence on others. The research findings can contribute to the theoretical framework of TPE, as well as provide empirical implication for pro-environment communication. / Detailed summary in vernacular field only. / 張晓. / Thesis (M.Phil.) Chinese University of Hong Kong, 2015. / Includes bibliographical references (leaves 64-82). / Abstracts in English and Chinese. / Zhang Xiao.

Kwong Lop Sam. / Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 60-63.