Distribution of selected heavy metals in sediment cores of Anzali Wetland, northern Iran

The Anzali wetland that located in southern margin of the Caspian Sea is subdivided into four subbasins (Sheyjan (eastern), Hendkhaleh (central), Abkenar (western) and Siakishem). In this study, we sampled 21 stations in the wetland. A site a core, 60cm long was taken and were analyzed for physico-chemical parameters such as pH, %LOI, %CaCO3 and four selected heavy metals (Zn, Cu, Pb and Cd) concentrations for two parts of cores (0-30cm and 30-60cm) that were measured after acid digestion by AAS method. The results show the wetland sediments have fine grain texture (sandy silt) and grain size decreases to the west as well as from top to the bottom of the cores, changing to silty-clayey and clay. These sediments with pH>7 contain %LOI ringing from 0.5-11% that changes from east to the west of the wetland. Concentration of Zn and Pb in these sediments is lower but Cu and Cd concentration are higher when compared with standard values. The highest value of Cd and Cu elements has been measured in Sheyjan (eastern) subbasin. Due to high mobility, Cd value is high in the deeper sediments of the cores. The results of heavy metal enrichment factor (EF) value and cluster analysis show that the high values of Cu are correlated to natural and geological sources and there are two possible sources of Cd anthropogenic and industrial activities in this area

Keywords:

Heavy metal , Anzali Wetland , Sediment , Enrichment Factor (EF) , Iran