Size distributions of inorganic and organic species in the atmospheric aerosol in Hungary

Abstract

Atmospheric aerosol samples were taken in different size intervals by means of a Berner-type cascade impactor. The samples were analyzed by using capillary electrophoresis, atomic absorption spectrometry as well as liquid and gas chromatography to determine the size distribution of water soluble inorganic and organic ions, metallic elements, polycyclic aromatic hydrocarbons and n-alkanes, respectively. The size distributions of ammonium and sulfate ions measured in this work were compared with those determined about 30 years ago: a decrease in the absolute concentration and an increase in the mass median diameter of both ions have been observed. The results indicate that the mass of the most important ions, sulfate and ammonium, are in the accumulation mode (0.125-1.0 μm in diameter) with a maximum in the size range of 0.5 and 1.0 μm. In summer the size distribution of nitrate is different, showing a maximum in the coarse mode (d > 1.0 μm). The form of the spectra of carboxylic and dicarboxylic acids is very similar to that of sulfate and ammonium, while some ions like calcium and carbonate are concentrated in the coarse mode. The size distribution of metallic elements is rather variable as a function of formation (e.g. combustion of different fossil fuels, metal industry and/or surface disintegration) and probably dynamic processes. Some of them like chromium and nickel have an important maximum in the size range of 0.0625-0.125 μm, while others (e.g. Al, Fe) are characterized by a peak in the coarse range. The major mass of polycyclic aromatic hydrocarbons is found in the accumulation mode (with larger sizes in winter), while n-alkanes are detected partly below the size of 0.125 μm and partly in the coarse mode owing to the combination of the effects of anthropogenic and biogenic sources.