Heavy Metals Bio-availablity (Zn, Cd, Ni, Cu, and Pb) in Sediments of Abshineh River

Heavy metals added to an aquatic system by natural and anthropogenic sources during their transport, are distributed between different compartments of ecosystems such as water and sediment. Meausrement of bioavailabity and mobility are required in order to understand the behavior of heavy metals in sediments and to prevent potential toxic hazards. Seventeen surface sediment samples were collected from 0-10 cm depth of rivers Abshineh and analyzed for total and bioavailable concentrations of zinc (Zn), cadmium (Cd), nickel (Ni), copper (Cu), and lead (Pb). Average total (± Standard Deviation) Zn, Cd, Ni, Cu, and Pb concentrations of the sediments were 93.08±20.66, 1.24±0.63, 57.72±13.08, 19.23±7.62, and 52.47±8.52 mg kg-1, respectively. The sediments were polluted with respect to Cd and Pb to some extent. Total metals concentrations were correlated with sediment physical and chemical properties. EC, organic matter, CEC, and clay were sediment parameters that showed significant positive correlations with total heavy metals concentrations indicating that heavy metals concentrations are controlled by sediments grain size. There is a highly significant correlation exit between bioavailable and total Zn and Cu which can be due to the common sources of introduction to the river. Percent of DTPA-extractable Cd was much higher than the others, which suggests that possible mobility of this metal from exchgeable phase. The bioavailability of the five studied metals from Abshined probably decline in the following order: Cd > Cu > Pb > Ni = Zn.