HASANZADEH HOSSEINABADI HASAN
Abstract
The present study on the determination and distribution of heavy metal concentration, i.e. Pb, Cu, Cr, Cd, Fe, Ni, Mn and Zn in water and in bed sediments of river Tajan have been studied from Alborze origin of river to join Caspian sea (a stretch of about 145 km. sq). Water and sediment samples were collected from 18 sampling stations at upstream, middle and downstream. These heavy metals were determined at monthly intervals for a period of October 2005 to September 2006 using Atomic Absorption Spectrophotometer (A.A.S). In the water and sediments of river Tajan varies in it's downstream at various points as most of the industries discharging heavy metals are situated in this area. Dilution during autumn season decreased the metal level even below the prescribed limit. The study reveals that monthly and seasonal average values of sampling stations of the river values may cross the tolerance limit if their inflow though domestic and industrial wastes in checked. Present observations revealed high concentrations of heavy metals at downstream sites, because huge quantity of partially domestic sewage and industrial effluents were discharged into the river at all these sites. While in sediments contents of these metals showed considerable variation at different sampling sites. This may be due to precipitation and sedimentation of these metals. It may be concluded that downstream sampling stations got more polluted than upstream sampling stations. The results of the analysis level that all the heavy metals at eighteen stations to compared of standards heavy metals in the order of their relative dominal were in the sequence Cr> Mn> Fe> Ni> Zn> Pb> Cd> Cu in water river and Mn> Cr> Zn> Ni> Cu> Pb> Cd> Fe in the sediment of river Tajan.