Source Identifying and Characterizing Physical and Chemical Fine Dust in Sarakhs City

The city of Sarakhs is located in in Khorasan Razavi province, the northeast of Iran and has a dry and desert climate. Although this city has no problem in the field of gaseous pollutants, but dust causes more unhealthy days than before. The purpose of this study was to investigate the physical and chemical properties, identify dust particles minerals over Sarakhs city and identify sources of dust storms. Spatial repetition of dry particle sedimentation has taken place during the summer and autumn seasons of 2019. This study was performed on fine round particles with a size of less than 10 micrometers at a height of 2-4 meters above the ground. Using Inductively Coupled Plasma (ICP) and XRD, metals and minerals of dust particles were identified and, then, using Scanning Electron Microscope (SEM) and Particles Size Analysis (PSA), particle shape and size were determined. According to the results, metals Ca, Al, Na, Fe, S, Ti, Ba, Mg, Zn, and Sr have the highest concentrations of dust in designated villages. The study of dust particle mineralogy showed that the dust has a terrestrial origin and is very similar to the minerals in the dust of Sistan plain and Hamoon wetland. The highest concentrations of clay minerals are: Kaolinite, Chlorite, Quartz, Calcite Gypsum. Ca and Al with the highest concentration among soluble metals indicate the origin of dust in the region. Also for elements such as Sr, S, and Gypsum, an evaporative source can be considered. The high concentrations of toxic and chemical elements including As, Pb, and Zn can be attributed to Khangiran refinery. Therefore, dust in Sarakhs region has three sources of local origin, evaporation and chemical.