Professor, Department of Physical and Environmental Sciences, UTSC
and Department of Chemistry, University of Toronto
In our lab, we are interested in chemistry and photochemistry that happens on surfaces which are exposed to the atmosphere. Such surfaces include those of aerosol particles, urban and ocean surfaces, as well as the exposed surfaces of snow and ice. We use tools from physical, analytical and theoretical chemistry to understand the processes which take place at these interfaces. Such processes can be very important in controlling the lifetimes of pollutants in urban atmospheres (we have shown that heterogeneous oxidation of polycyclic aromatic hydrocarbons represents a significant fate for these compounds in cities), and for changing the propensities of aerosol particles to take up water vapour (and hence act as cloud condensation nuclei), and also to interact with solar of terrestrial radiation (affecting local and global temperatures). Reactions taking place on biofilms, ubiquitous at the ocean-air interface, can influence CO2 uptake into oceans, and the release of organic compounds from seawater. Chemistry and photochemistry on ice and snow surfaces seems to be more efficient than in liquid water; this may have important consequences for urban pollutant concentrations in winter.