MP3 Heterogeneous Chemistry of Atmospheric Particles and Trace Gases
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(DIA-1117-842635) Seasonal Variability of Organic and Inorganic Compounds in Surface Films.

Hernandez, N¹, Truong, J¹, Diamond, M¹, ¹ University of Toronto, Toronto, ON, Canada

ABSTRACT- Atmospherically deposited compounds cause the growth of surface films on impervious surfaces that change their functionality. Here we explore the seasonal variability of inorganic and organic compounds in surface films including metals, sulphate, nitrate and organic acids (monoalkanoic acids) and n-alkanes. Film concentrations were quantified by sampling windows on a monthly basis at the University of Toronto located in downtown Toronto in 2002 and 2003. Chemical concentrations were as follows: 3.8 to 16.6, 2.0 to 19, 0.8 to 8.4 mg/m² for nitrate, sulphate, and a total of 17 metals, respectively. In general, higher concentrations were observed during winter months for all compounds. The coefficients of variation between months were 0.43, 0.82, and 0.54 for nitrate, sulphate, and metals, respectively. Concentrations of n-alkanes (C9-30), monocarboxlyic acids (C9-30) and PAH (17 compounds) varied from 1000 to 6000, 4000 to 22,000 and 60 to 170 ng/m² and did not show a strong seasonal pattern. The lack of a seasonal pattern is surprising since the n-alkanes and monocarboxlyic acids are dominated by compounds of biogenic origin, which are expected to be more abundant during warm months. Several hypotheses are proposed to explain this apparent paradox.

Key words: surface films, inorganics, organics