Tham khảo tài liệu 'environmental technologies part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Assessment of Air Quality in an Urban Area of Belgrade Serbia 233 Fig. 9. Coarse Fe rich particle from the sample November 2003 and X-ray microanalysis spectrum Sulfates are characterized by a strong S line in the X-ray spectrum and mostly by the presence of Ca or Fe Pb and K. These particles are formed as a result of the reaction in the atmosphere between sulfur compounds and other substances. They predominate in the fine fraction and have round forms. Sulfate clusters often with sharp edges are mainly composed of Ca sulfates they arise from the reactions between Ca carbonate materials and sulfurous compounds and have been found in the coarse particle range. Oxides of Al Zn Cu Ni Pb Ti with spherical morphology abundant in the submicrometer range are identified as anthropogenic fly ash. Many particles which could not be classified into one of these groups found in the coarse particle range were mixed aggregates irregularly shaped consisting of soil and road dust Si Al with minor constituents such as C Fe Mg Ca Ba Pb K S Zn Ni Cu Ti. Coarse metal-rich particles of irregular form liberated in industrial processes were also found Fig. 9 . Biological particles pollen bacteria fungi spores etc. are recognized by their characteristic morphology as important constituents of the coarse particle fraction in the PM10 samples especially during summer period. Scanning electron photomicrographs of particles deposited on leaf surfaces showed a general appearance of adaxial and abaxial surfaces of hypostomatic leaves of A. hippocastanum and C. colurna sampled in a dry period at the end of the vegetation seasons Tomasevic et al. 2005 . Approximately 10 - 15 the leaf surface was covered with deposited particles. A greater density of particles was observed on A. hippocastanum than on C. colurna. This could be explained by different epidermal characteristic such as surface roughness which was more prominent in A. hippocastanum than for C. colurna. Particles were present
