Composition and mixing state of the urban background aerosol in the Rhein-Main area (Germany)

• Published in: Atmospheric environment (1994) Vol. 41; no. 29; pp. 6102 - 6115
• Main Authors: Vester, Barbara P., Ebert, Martin, Barnert, Eric B., Schneider, Johannes, Kandler, Konrad, Schütz, Lothar, Weinbruch, Stephan
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-09-2007; Elsevier Science
• Subjects: Applied sciences; Atmospheric pollution; Electron microscopy; Exact sciences and technology; Mixing state; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Secondary aerosol; Soot; Urban background aerosol; Europe; Germany; ANE, Germany; Secondary aerosol; Mixing state; Electron microscopy; Soot; Urban background aerosol; Background concentration; Secondary pollutant; Air quality; Urban area; Ultrafine particle; Ion composition; Mixture; Coarse particle; Particle size distribution; Fine particle; Morphology; Aerosols; Air pollution; Chemical composition; Concentration distribution
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2007.04.021

Size-resolved aerosol particle samples in the size range 0.1–10
μm aerodynamic diameter were collected in the years 2003 and 2004 at an urban background station in Mainz, Germany. Size, morphology, chemical composition and mixing state of more than 5400 individual particles of 7 selected sampling days were analyzed in detail by scanning electron microscopy and energy-dispersive X-ray microanalysis. In addition, transmission electron microscopy, aerosol mass spectrometry and atomic force microscopy were applied to obtain detailed information about the mixing state of the particles. The fine particle fraction (diameter<1
μm) is always dominated by complex secondary aerosol particles (⩾90% by number) independent from air mass origin. These particles are complex internal mixtures of ammonium and sodium sulfates, nitrates, and organic material. Between 20% and 40% of the complex secondary aerosol particles contain soot inclusions. The composition of the coarse particle fraction (>1
μm diameter) is strongly dependant on air mass history with variable abundances of complex secondary aerosol particles, aged sea salt, silicates, silicate mixtures, calcium sulfates, calcium sulfate/carbonate mixtures, calcium nitrate/carbonate mixtures, biological particles, and external soot.
The dominance of complex secondary aerosol particles shows that reduction of the precursor gases is a major goal for successful reduction strategies for PM
10.