Primary emissions of volatile organic compounds (VOC) can directly influence human health. Their atmospheric transformation also leads to the formation of lower volatility species which contribute to secondary organic aerosol (SOA). These in turn have both climate and health impacts. The first part of this presentation focuses on field measurements of VOCs made over the Greater Toronto Area (GTA) onboard Environment and Climate Change Canada’s mobile platform. VOCs such as benzene and toluene are known to have adverse health effects and a good understanding of their spatial variability at the neighbourhood level, as well as their relationship to traffic-related air pollution,  is required for accurate exposure assessment. VOC measurements made across the GTA will be presented; preliminary results show that our mobile strategy is effective for pollutant mapping and for determination of on-road emissions. The second part of the talk will shift from the field to the lab and focus on the fate of a semi-volatile organic compound, methylglyoxal (MG), at the air-water interface. Recently, it has been suggested that aqueous-phase processing of atmospheric α-dicarbonyl compounds such as MG could constitute an important source of SOA. MG is known to be surface active but an improved description of its surface behaviour is crucial to understanding MG-SOA formation, in addition to its gas-to-particle partitioning and cloud forming potential. In the Richmond lab, we investigated MG surface adsorption, focusing on its hydration state at the air-water interface. This study employs a combined experimental and theoretical approach involving vibrational sum frequency generation spectroscopy (VSFS) with molecular dynamics simulations and density functional theory calculations. Together, the experimental and theoretical data suggest that MG exists predominantly in a hydrated state at the interface, with higher diol-tetrol ratios at the surface than are found in the bulk. <br/>

From the field to the lab: Atmospheric organics in urban air and at the air-water interface

255th National Meeting (2018)

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