Roofs that are fully or partially covered with vegetation have numerous benefits in an urban environment. These “green roofs” provide added insulation to buildings, create an aesthetically pleasing habitat and urban landscape, decrease urban heat island effect, and reduce stormwater runoff. However, the role that green roofs play in acting as a sink for contaminants is less well understood.

EMPOWER trainee Alex Johnson, who is a graduate student in the Civil & Environmental Engineering Department, is comparing contaminant amounts in runoff from green versus gravel roofs in Syracuse, NY, to assess the degree to which green roofs act as contaminant sinks. Alex also conducts field experiments to estimate the washoff of dry deposited aerosols from building roof surfaces during rainstorms. He recently presented some of his findings at the American Association for Aerosol Research (AAAR) 35th Annual Conference in Portland, Oregon. His presentation, entitled “Deposition and Washoff of Atmospheric Trace Metals and Anions from Two Large Building Roofs,” was coauthored with his advisor, Cliff Davidson.