title: Modeling urban films using a dynamic multimedia fugacity model.
abstract: A thin film coats impervious urban surfaces that can act as a source or sink of organic pollutants to the greater environment. We review recent developments in the understanding of film and film-associated pollutant behavior and incorporate them into an unsteady-state version of the fugacity based Multimedia Urban Model (MUM), focusing on detailed considerations of surface film dynamics. The model is used to explore the conditions under which these atmospherically-derived films act as a temporary source of chemicals to the air and/or storm water. Assuming film growth of 2.1 nm d(-1) (Wu et al., 2008a), PCB congeners 28 and 180 reach air-film equilibrium within hours and days, respectively. The model results suggest that the film acts as a temporary sink of chemicals from air during dry and cool weather, as a source to air in warmer weather, and as a source to storm water and soil during rain events. Using the downtown area of the City of Toronto Canada, as a case study, the model estimates that nearly 1 g d(-1) of ∑(5)PCBs are transferred from air to film to storm water.
authors.affiliation: Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Csiszar
authors.forename: Miriam L
authors.initials: ML
authors.lastname: Diamond
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Thibodeaux
mesh_terms: D000393:Air Pollutants; D002170:Canada; D002947:Cities; D008962:Models, Theoretical; D019212:Multimedia; D011078:Polychlorinated Biphenyls; D011891:Rain; D014874:Water Pollutants, Chemical
chemical_list: D000393:Air Pollutants; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls