Distribution of Metals, Chemical Partitioning, Pollution and Origins in Riverbed Sediment

Water quality and metal contents of sediments were measured in Zayandeh-Rood River. Zayandeh-Rood is one of the most important rivers of Iran. The river water is used for drinking, industrial and agricultural purposes. The anthropogenic impact on the river over the last three decade has proven to be extremely negative due to the quick development of industry. Physico-chemical parameters of water were measured in study area. Total concentration of metals was measured in bulk sediment samples (0-5cm). Study of water parameters indicated BOD and COD values are more than surface water quality standards in some segments. Sediments analysis revealed some metals accumulation is very close to normal and some beyond threshold limits. Comparing with the maximum background values indicates river is polluted in central segmentation. Higher concentrations of elements were observed in sampling location 4 and 5. Lead was the highest in terms of contamination level, especially after Zarin-Shahr effluents, followed by Nickel. Results indicated the origin of Lead was mainly anthropogenic and for others was lithogenic. I Index values indicated poll a non-polluted and less-polluted environment throughout the river. I values are in a well agreement with poll results of chemical partitioning of metals.