W4 AM Environmental Fate of Mercury
Wednesday, 16 November 2005: 8:00 AM - 11:40 AM in Ballroom 4

(ECK-1117-680942) Mercury pollution dynamics in urban areas: the influence of the built environment on surface and air fluxes.

Eckley, C¹, Branfireun, B¹, ¹ University of Toronto Mississauga, Mississauga, ON, Canada

ABSTRACT- Multiple studies have shown that urban areas contain elevated concentrations of mercury when compared to rural areas. The objective of our research is to determine how built urban surfaces (such as windows and pavement) influence the flux of mercury between urban environmental compartments. Understanding the fluxes of mercury between compartments (air, surface, water) is important to understanding how to manage/reduce urban environmental mercury concentrations. This research focuses specifically on the flux of mercury from the atmosphere to urban surfaces and the flux from surfaces back to the atmosphere. Accumulation of mercury on windows in Toronto, Canada was monitored monthly for 1 year. Windows were sampled with variations in exposure to precipitation, aspect, and angle. The results showed that mercury concentrations on sheltered windows (average: 56 ng/m²) were an order of magnitude higher than windows exposed to precipitation washoff (average: 4 ng/m²), suggesting that mercury deposited to impervious urban surfaces can be readily removed. Mercury accumulation on windows was also found to vary with surface aspect and angle. Similar to windows, accumulation on paved surfaces varied with exposure to precipitation. The surface concentration of mercury on paved surfaces was observed to change by over an order of magnitude between wet and dry periods. Size separation of street dust revealed that fine particles had significantly higher mercury concentrations than coarse material at all the sites studied. Overall, the average mercury concentration on paved surfaces (610 ng/m²) was much higher than observed on windows. The surface-to-air flux of mercury from windows and paved locations was determined using a dynamic flux chamber. The magnitude of the surface-to-air flux was dependent on ambient conditions and was not strictly related to surface mercury concentrations.

Key words: Mercury, Urban, Flux