Assessment of contamination and mobility potential of potentially toxic elements in the Zayanderud sediments, Isfahan metropolis

Sediment environment has a special importance in the ecosystem, because it acts as a sink for the potentially toxic elements in the water/sediment environment and also in a special conditions can be a major source for the contaminant elements. The aim of this study is to assess the concentration and contamination potential of potentially toxic elements in the Zayaderoud sediments with a special emphasis on the role of the Isfahan metropolis. For this purpose, 23 sediment samples were collected from the Zayanderud River within the boundary of the Isfahan city. After preparation process, the total concentration of target elements was measured by ICP-OES method. Also, single extraction methods were applied to the samples using 0.43M acid acetic and 0.05M EDTA leaching solutions. Evaluation of the total concentration results using environmental pollution indices showed that the concentrations of Ag, As, Cu, Pb, Zn, and S were higher than the natural background values suggesting an anthropogenic source. The contamination potential was increased from upstream to the downstream, especially after treatment plant located south of the Isfahan. According to the PCA multivariate statistical method, elements with the same sources fall into the same groups, so that the elements with the anthropogenic source showed the same group with high correlation. Determination of the soluble fraction using single extraction methods showed that 50 percent of statistical population of Cu and S has mobility factor higher than 30 percent corresponded with the high risk potential. Also, 50 percent of statistical population of Pb, Mn, and Zn showed mobility factor between 10 to 30 corresponded with the medium risk of these elements.