CHARACTERIZATION OF AMBIENT AIR PARTICLE-SIZE FRACTIONS IN 3 GERMAN CITIES WITH THE AID OF ELECTRON-MICROSCOPY

Multistage-filtration samplers offer the opportunity to analyze dust f ractions deposited on corresponding stages of the sampler. In this inv estigation, a typical two-stage sampler was used in the cities of Dort mund (mining and steel industry), Dusseldorf (lesser industrial activi ties), and Duisburg (steel industry), North Rhine Westphalia. The purp ose of this study was to compare the composition of dust fractions wit h the aid of analytical electron transmission microscopical methods. T he particle size distribution was similar in the cities, the 50% value of the equivalent diameter was 0.8 mu m. Analytical results are prese nted for different mineral classes with approximately 30 single minera ls in all cities. The highest concentration values in the fine dust fr action were silicate minerals, while the sulfate content was very high in the coarse dust fraction in all cities.