Contamination of Two Heavy Metals in Topsoils of the Urban Parks Asadabad, Iran 2013

Background & Aims of the Study: Heavy metals are the most important contaminants in the soil. Due to their non-biodegradable property, heavy metals can persist in the ecosystem for a long time. Therefore, this research focuses on heavy metal contamination in urban park soils in Asadabad, Hamedan, Iran. Materials & Methods: Altogether 18 composite soil samples were collected at depths 0-20 cm from urban parks. The urban soil samples were digested in aqua regia according to 11466 ISO standard methods. Total concentrations of Cd and Pb were measured by Atomic Absorption Spectrometer. Results: Concentrations of Cd and Pb varied in the range of 0.15-0.22 and 7.5-27.5 mg/kg, with mean values of 0.18 and 20.72, respectively. The mean values of geo-accumulation index ( Igeo) were (-0.70) and (0.04) for Cd and Pb respectively. The urban soils in Asadabad, Iran, were uncontaminated by Cd and uncontaminated until moderately contaminate with Pb. There was no significant correlation between Pb and Cd (r2=0.16), it seems that these metals may have derived from different sources. Conclusions: Findings showed that Cd was usually associated with parent material in the soils, while Pb was controlled by anthropogenic activities such as traffic and residential wastes. Also the results indicated that urban park's location affects the total metal contents of the  analyzed soils.