Seasonal variability of Concentration, Chemical Composition and Aerodynamic Distribution of Particulate Matter in Tehran

In recent years, the concentration of suspended particles in the atmosphere of Tehran has been increasing. Therefore, we see more polluted days in this city. This situation has had economic, health, welfare, social and negative effects. In this study, we want to investigate the seasonal changes in particle concentration, chemical composition and aerodynamic distribution in Tehran. Atmospheric matter sampling was performed in four seasons in ۲۰۲۰ to ۲۰۲۱. Sampling was performed by Andersen Cascade Impactor ۸ stages. Also, in each period of sampling process, samples were prepared to study the physical and chemical properties by SEM method. The particle surfaces with magnifications of ۵۰۰۰x, ۱۰۰۰۰x, ۲۰۰۰۰x and ۵۰۰۰۰x were studied. The EDS method was used to study the chemical composition of particulate matters. The results show that the north and northwest of the region are affected by the prevailing wind and a large volume of particulate matter produced by fixed and moving pollutants move to these areas. The highest and lowest concentrations of total PM collected in Azadi square and Hakimiyeh were ۱۶۲.۱۱±۱۶.۵ µg/m۳ and ۱۳۹.۲۱±۱۲.۲۲ µg/m۳, respectively. Also, the distribution of particulate matter in the western and southern regions of the region was more towards coarse particles, while the distribution of particles in the eastern and northern regions was more towards smaller particles. Due to the geomorphological characteristics of the region, the production of particulate matter should be controlled and monitored by moving and fixed sources, to reduce the destructive effect of particles on the health of people living in the region.

Keywords:

Air pollution , SEM/EDX , Tehran , PM , Particle Size