Size-segregated mass concentration and water soluble inorganic ions in an urban aerosol of the Central Balkans (Belgrade)

The distribution of nano/micron inorganic main ions in the size-segregated urban aerosol of Belgrade center was studied during the summer–autumn of 2008. The particle size distribution in the size ranges Dp ≤ 0.49 µm, 0.49 ≤ Dp ≤ 0.95 µm, 0.95 ≤ Dp ≤ 1.5 µm, 1.5 ≤ Dp ≤ 3.0 µm, 3.0 ≤ Dp ≤ 7.2 µm and Dp ≥ 7.2 µm was measured. The aerosol samples were submitted to gravimetric and chemical analyses. The obtained mean mass concentration of the PM fractions was in accordance with an urban aerosol distribution. The aerosol mass concentrations were determined by gravimetric measurements (mGM) and, analyzed by ion chromatography for Na+, NH4+, K+, Mg2+, Ca2+, Cl–, NO3–, PO43– and SO42–. The mean random uncertainties associated with the determinations of Na+, NH4+, K+, Mg2+, Ca2+, Cl–, NO3– and SO42– were assessed. The absolute highest concentration is found for SO42– (1555.8 ± 973.6 ng m–3) in the range of Dp ≤ 0.49 µm with an average participation of 8.19 % to the total mass of the particles. The highest coefficients of correlation were found between NH4+ and SO42–. Principal component analysis, PCA, was used for the identification and evaluation of the contributions of the main emission sources to the contents of water soluble ions in the urban aerosol. The dominant process of particle formation was chemical reactions between gaseous precursors. The formation of (NH4)2SO4 was the dominant process. The influences of local urban and regional industrial sources were identified as contributors to the contents of the main ions in urban aerosol of Belgrade. An effect of marine aerosol was observed.