Laser mass spectrometric analysis of organic atmospheric aerosols. 2. Elucidation of urban air pollution processes

The dynamic behavior of aerosol-bound polycyclic aromatic hydrocarbons (PAH s) and other polycyclic aromatic compounds (PACs) in urban air was studied over the course of several whole days, both next to a street with heavy tra ffic and in a city park. Two-step laser mass spectrometry, a highly sensiti ve and selective technique, allowed measurements with 15 min time resolutio n. Large variations in particle concentration and chemical composition were observed, reflecting the contributions from Diesel trucks and gasoline-pow ered cars to urban aerosols. These sources were clearly identified using sp ecific mass spectral patterns. Photochemically induced decay of oxygenated polycyclic aromatic hydrocarbons (OPAHs) was observed to occur within only a few hours. Rapid speciation of aerosol-bound organic carbon is now possib le to complement data on routinely monitored atmospheric pollutants.