The Effect of Land-Use Changes on the Amount of Heavy Metal Pollution in Urban Runoff in Tehran

Background Aims of the Study: Urban development trends and land-use changes harm the quality of urban runoff. Heavy metals are one of the most important pollutants in urban runoff. This study aimed to investigate the amount of heavy metal pollutants (Zn, Pb, Cu, As, Hg, and Cd) in different land uses in a densely populated urban area of Tehran. Materials and Methods: Six stations were selected for urban runoff sampling in five land uses. Land uses were residential, commercial, industrial, traffic, and outdoor. A station (sixth station) with mixed land use was selected, which included the runoff of all uses. The event mean concentration (EMC) model was used to estimate this study’s heavy metal pollution load. Results: The amount of all heavy metals except Arsenic in fields with industrial use was higher than other land uses (Cu=0.292 mg/l), (Pb=0.6166 mg/l), (Zn=1.36 mg/l), (Cd=0.0114 mg/l), and (Hg=0.1332 mg/l). While the amount of Arsenic metal in the station with outdoor land use (AS=0.111 mg/l) was the highest. Conclusion: The results of this study indicate that the risk of metals on long dry days without precipitation is very high. Uncertainties related to the accumulation of pollution and various human activities can be attributed to the high amount of heavy metals in the mixed land use compared to land use alone.