Session: Aquatic Photochemistry:

In Canada and the United States, the largest anthropogenic source of primary fine particulate matter is road dust, which consists of a mixture of brake and tire wear, pavement particles, crustal material, semi-volatile vehicle exhaust components, and natural organic matter. To date, road dust research has focused on its negative heath effects, with few studies focusing on its environmental reactivity. Therefore, our group investigated road dust collected from a single location in Edmonton, Alberta, and found that it is a photochemical source of the atmospherically relevant oxidant, singlet oxygen. Here, we extended this work by measuring the singlet oxygen photochemical production by eight road dust samples originating from three different road types (residential, arterial, and expressway) collected in Toronto, Ontario. From our samples, we find that singlet oxygen production increases linearly with their loss on ignition, which implies that the organic matter in road dust is responsible for its photoreactivity. In addition, we report the quantum yields for singlet oxygen production by aqueous road dust extracts and compare them to dissolved organic matter from other atmospheric and aquatic environments. These results highlight the photochemical activity of road dust and demonstrates that its photochemistry has the potential to influence the lifetime of urban pollutants in the atmosphere.

Clare Wiseman

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