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Physical and Chemical Characterization of Urban Grime Sampled from Two Cities

2020; American Chemical Society; Volume: 4; Issue: 10 Linguagem: Inglês

10.1021/acsearthspacechem.0c00192

2472-3452

Corey R. Kroptavich, Shan Zhou, Shawn F. Kowal, Tara F. Kahan,

Slime Mold and Myxomycetes Research

Urban grime can be an important substrate for heterogeneous reactions in cities. Studies performed using laboratory-prepared urban grime proxies and urban grime collected from the field indicate that the physicochemical properties of urban grime can greatly affect heterogeneous reaction rate constants. We investigated several properties of urban grime collected from two cities in the north-east region of the United States of America. Optical and Raman microscopy indicated that urban grime collected from these regions consists primarily of particles as opposed to a uniform film. Total carbon analysis and ion chromatography were used to determine the bulk composition of the urban grime from both cities. Comparing these results to reported compositions of urban grime from cities in Canada and Europe showed strong similarities between different locations, with some variations for specific ions, such as higher chloride levels in North American cities and higher sulfate levels in some European cities. Absorbance spectra demonstrated that urban grime can absorb sunlight across the ultraviolet region. It may therefore be able to participate in photochemical reactions (either hindering them via processes such as the inner filter effect or enhancing them via processes such as photosensitization).