Elucidating the atmospheric chemistry of organic nitrates and reactive halogens in laboratory experiments and in ambient air

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There is growing public awareness that the composition of the atmosphere can be altered by man-made emissions with often unintended consequences. One example is the impact of persistent greenhouse gases on climate; another is the impact of pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) on regional air quality. NOx is a byproduct of high-temperature combustion and found, for example, in automobile exhaust. VOCs are emitted naturally by vegetation but also by a multitude of human activities. Accurate knowledge of the impact of NOx and VOCs and their decomposition products on the abundances of ozone and fine particulate matter is needed for policy makers to make informed decisions on pollution control. This research program will address some of the key uncertainties in the chemical transformations of NOx and VOCs as well as naturally occurring halogenated compounds (e.g., iodine containing species) in the atmosphere. The initial focus is on development of novel instrumentation to accurately measure some key intermediates (for example, organic nitrates) in ambient abundance. Students at both the graduate and undergraduate level will be involved in this research. Through their training, the public will gain a pool of qualified candidates to staff regional environmental agencies and industrial workplaces alike. The specific techniques to be developed and deployed are cavity ring-down and cavity enhanced-absorption spectroscopy, mass spectrometry, and electrophoresis. The second focus of this research program is on studying relevant transformations taking place in controlled laboratory experiments. For example, we will measure uptake rates of semi-volatile organic nitrates on fine particulate matter to better constrain ambient air quality models. Finally, we will take some of our instruments to the field and make ambient air measurements in and around Calgary, throughout the province of Alberta, and funding permitting, in regions heavily influenced by pollution (such as the Lower Fraser Valley, or Southern Ontario). Our measurements will help refine regional air quality models and ultimately allow more accurate predictions of the impacts of pollutants on air quality.