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

越来越多的公众意识到，人为排放可能会改变大气的组成，往往会产生意想不到的后果。一个例子是持久性温室气体对气候的影响；另一个例子是氮氧化物(NOx)和挥发性有机化合物(VOCs)等污染物对区域空气质量的影响。NOx是高温燃烧的副产品，例如在汽车尾气中发现。挥发性有机化合物是由植物自然排放的，也是由多种人类活动排放的。政策制定者需要准确了解NOx和VOCs及其分解产物对臭氧和细颗粒物丰度的影响，以便就污染控制作出明智的决定。 这项研究计划将解决NOx和VOCs以及大气中自然产生的卤化化合物(如含碘物种)的化学转化中的一些关键不确定性。最初的重点是开发新的仪器，以准确地测量环境中的一些关键中间体(例如，有机硝酸盐)。研究生和本科生都将参与这项研究。通过培训，公众将获得一批合格的候选人，为地区环境机构和工业工作场所提供工作人员。待开发和部署的具体技术包括腔衰荡和腔增强吸收光谱、质谱学和电泳法。这项研究计划的第二个重点是研究在受控实验室实验中发生的相关转变。例如，我们将测量半挥发性有机硝酸盐在细颗粒物上的吸收速率，以更好地约束环境空气质量模型。最后，我们将把我们的一些仪器带到现场，在受污染影响严重的地区(如下弗雷泽山谷或安大略省南部)，在资金允许的情况下，在卡尔加里及其周围地区进行环境空气测量。我们的测量将有助于完善区域空气质量模型，并最终允许更准确地预测污染物对空气质量的影响。

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.