Morphological diversity and composition of air pollutants’ particles deposited on Platanus Orientalis, Ulmus Carpinifolia and Robinia Pseudacasia trees’ leaves in Scanning Electron Microscopy

In this study, the shape, structure and elemental composition of the deposited particles on the leaves of Ulmus Carpinifolia, Platanus Orientalis, and Robinia Pseudacasia in Azadi and Chitgar areas in Tehran was investigated through individual particles analysis with SEM-EDX. The properties of 128 particles were analyzed through SEM-EDX. Thirty-four elements were identified in all the samples. The diameter of particles in Azadi was greater than Chitgar. The average diameter of particles was 7.26 microns. The average diameter of particles was 7.51 microns in Platanus Orientalis, 6.88 microns in Ulmus Carpinifolia, and 4.42 microns in Robinia Pseudacasia, respectively. The diameter of 45% of the particles was smaller than 2.5, 31% of the particles between 2.5 to 10, and 23% of the particles bigger than 10 microns. The distribution of metal particle size in all samples showed that the average diameter of the metal particles was 14.05 microns and the diameter of 14.28% of the particles was below 2.5, 42.85% between 2.5 to 10, and 42.85% was above 10 microns. Various structures of the elements were observed in the areas. Particles morphology showed that the origin of particles production is natural resources and they are man-made. In general, the average diameter of deposited particles on Platanus Orientalis and Ulmus Carpinifolia was more than those on Robinia Pseudacasia. Moreover, the particles diameter distribution showed that in Platanus Orientalis and Ulmus Carpinifolia particles are deposited with different sizes while in Robinia Pseudacasia there is less variation in particles size.