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Urban grime refers to films made of a complex chemical mixture of organics and inorganics deposited on outdoor surfaces. The specific chemical composition of such films can vary considerably due to geographic and seasonal influences. We compared the seasonal change of grime's water-soluble inorganic ion content in a rural (Thamesford), suburban (Oshawa), and urban city (Toronto) in southern Ontario, Canada. Sodium, calcium, chloride, nitrate, and sulfate amounts in grime were collected and quantified over four seasons in Oshawa, ON and Thamesford, ON and compared with results from a previous study in Toronto to elucidate differences. We found that all three regions displayed a clear seasonality in sodium and chloride consistent with winter road salt inputs and chloride loss in summer. Mole fractions of sulfate were consistently the lowest of the measured ions, and NO3−/SO42− ratios showed a winter–spring minimum and summer–fall maximum. Urban–rural differences in the seasonal changes of ionic mole ratios suggest that additional chloride displacement by nitrate occurs within grime in Toronto that is not present in the two other rural/suburban cities in the same region. [ABSTRACT FROM AUTHOR]

Using glancing-angle laser-induced fluorescence (GALIF) spectroscopy as a probe, the partitioning of naphthalene, fluoranthene, pyrene, umbelliferone, phenol red, and bisphenol A from bulk solution to the air–water interface was examined in both pure water and aqueous solutions of 6 mM octanol. Previous studies provided similar Langmuir adsorption isotherms for anthracene and imidazole 2-carboxaldehyde. The surface partitioning behaviour of each compound in both environments was well described using a Langmuir adsorption model; partitioning coefficients were derived from the fits to such isotherms. Only the PAH molecules, naphthalene, fluoranthene and pyrene, saw an enhancement in the surface partitioning in octanol solution compared to pure water. The surface partitioning to pure water surfaces could be fairly well described using a one parameter linear free energy relationship based on either solubility or KOW. [ABSTRACT FROM AUTHOR]