Source apportionment of heavy metal with UNMIX in ambient air of Ahvaz City, Southwest of Iran

Although particulate matter (PM) consists of various compounds, heavy metals are essential constituents because of their harmful effects on human health. The purpose of this research project was to determine heavy metal concentrations in particulate matters (PM10) in ambient air and source apportionment of heavy metals with UNMIX model in ambient air of Ahvaz, Iran. In 2010, the World Health Organization named Ahvaz as the world’s most air polluted city. Ambient air was sampled at five locations around the city in winter 2018 and summer 2019 to measure PM10 according to ASTM; D4096 Standard. Further, the air sampling filters were analyzed by the acid digestion method and atomic absorption spectroscopy to determine the concentration of 16 heavy metals in the particulates, namely Al, V, Cu, As, Si, K, Ni, Pb, Cd, Mn, Fe, Zn, Ca, Cr, Ti, and Se. The PM10 concentrations in ambient air ranged from 22.335 to 463.36 μg/m3. The lowest concentration was observed at Station 3 northeast of the city in winter and the highest at Station 1 in the city center in the summer. The average PM10 concentration was found to be 121.4 μg/m3. The UNMIX model was used to determine the origins of the heavy metals which showed that the main sources of PM10 are background dust (70%), industrial and mining activities (22%), and motor vehicles (9%).