AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Deposition and Washoff of Atmospheric Trace Metals and Anions from Two Large Building Roofs
ALEXANDER JOHNSON, Cliff Davidson, Syracuse University
Abstract Number: 69 Working Group: Urban Aerosols
Abstract Building roofs are receptors of dry deposited aerosols. During a rainstorm, these aerosols may be washed off and contaminate stormwater runoff. Wet deposition can also contribute contaminants. However, there is limited understanding of the contributions of dry and wet deposition in contamination of runoff from building roofs. In addition, the potential for green roofs to act as sinks for dry and wet deposited contaminants is not well understood. Here we report the results of studies on two adjacent roofs in downtown Syracuse, New York: a 1.5 acre green roof on the Onondaga County Convention Center and a 1.3 acre asphalt roof on the War Memorial Sports Arena.
Fluxes of manganese, copper, lead, sulfate, and nitrate were measured using symmetric airfoils during dry weather periods of at least three days on the Syracuse University campus near downtown. Airborne concentrations were simultaneously measured. The dry deposition velocity for each contaminant was calculated by dividing the flux by the airborne concentration. Preliminary deposition velocities for manganese were determined to be 2.04, 1.43, and 0.733 cm/s for July 22-25 2015, November 15-18 2015, and January 21-24 2016, respectively. For the same sampling events, preliminary deposition velocities for copper were calculated as 1.34, 0.57, and 0.34 cm/s while those for lead were computed as 0.65, 0.40, and 0.26 cm/s. During rainstorms following dry periods of at least three days, fresh precipitation was collected and analyzed for the same contaminants to estimate wet deposition. In addition, stormwater runoff was collected from the roofs on the Convention Center and Sports Arena. These data are being used to compute a mass balance for each contaminant to estimate the amount washed off the asphalt roof as well as the potential leaching from the green roof.