Distribution of Ni, Cr, Sr, Cu, and Zn in the Fine-Grained Sediments of Anzali Wetland

The Anzali wetland is highly important for the particular ecologic, economic and social conditions. Several rivers discharge to Anzali wetland after passing through surrounding forests, towns and villages. Sampling of the sediments of Anzali wetland was carried out at 22 sampling points located in the inflowing rivers and the canals connecting the wetland to the Caspian Sea in order to determine the heavy metals concentrations and also physicochemical properties influencing concentration of these elements. The major clay minerals of these sediments are montmorillonite, chlorite and kaolinite in their order of abundances. The result showed that the concentration of Cr, Cu and Ni increased in the samples with higher amount of clay and the Zn concentration increases in the samples containing montmorillonite and illite. Increases of the Cr and Cu concentrations and decreases in the Ni concentration conform to increase in the amount of TOC. The Ni concentration was higher in the samples with higher Fe and Mn concentration. The amount of calcium carbonate is positively correlated with the Sr concentration. According to the enrichment factor, Cu and Zn showed average enrichment in just one sample. Ni, Sr and Cr were depleted in the fine-gained sediments of Anzali wetland.