Investigation of pollution and enrichment indices of heavy metals transported by atmospheric dust particles in the metropolis of the cities of Khuzestan province

Background and Objective: Due to the spread of dusty air and the transfer of these particles to the cities of Khuzestan province, it is very important to study the status of these particles in terms of heavy metal pollution and their pollution status. Materials and Methods: In this study, the concentrations of Cr, Cu, Zn, Pb, Ni, Mn, Mg and Fe in the air of 4 cities of Khuzestan province (Ahvaz, Dezful, Mahshahr and Abadan) in dusty and dust-free conditions over a period of 9 months (autumn, winter and spring) were measured in 2018-2019. Due to the spread of dusty air and the transfer of these particles to the cities of Khuzestan province, it is very important to study the status of these particles in terms of heavy metal pollution and their pollution status. Results: 48 samples in contaminated conditions and 48 samples in non-contaminated conditions were collected at the specific points and exact times using a High Volume sampling pump with a flow rate of 110 L/min for 6 hours. Metal concentrations were measured using ICP. Except for Ni, Mn and Mg, the mean concentration of other studied metals were higher at dusty conditions as compared with their values in non-dusty conditions (p < 0.05). In dusty and non-dusty air conditions the order of heavy metals based on their concentrations were obtained as following: Zn> Mg> Mn> Ni> Cr> Pb> Fe> Cu and Mg> Mn> Ni> Pb> Fe> Cr, respectively. This result shows that the origin of zinc and copper metals and the increase in chromium concentration in polluted air are due to the entering of dust and pollution transfer from the outside area into cities. The cities of Ahvaz, Dezful, Mahshahr and Abadan were highly enriched in terms of heavy metals pollution either in dusty or non-dusty conditions. Conclusion: The findings of this study showed that despite low concentration of heavy metals in airborne dust particles in clear and dusty air, high health risks of metals such as zinc in cities of Khuzestan province, especially Mahshahr are probable. Further investigation showed that particles are generally derived from intra-city or provincial activities, which call for more attention due to the drought conditions that attributes to more dust formation.