Samar Mortazavi - Environmetal Department, Faculty of Natural Resources and Environment, Malayer University, Malayer, Iran
Masoud Hatami - Environmetal Department, Faculty of Natural Resources and Environment, Malayer University, Malayer, Iran

Background & Aims of the Study: Heavy metals pollution in aquatic ecosystems threats livingorganisms health and environment. Hence, the present study aims to assess concentration oflead, chromium, copper, zinc and their ecological risk in the surface sediments of the BasharRiver during the summer and winter seasons.Materials & Methods: This is a field study; sampling of surface sediment was done in 8stations in 2016. The samples were digested by the composition of ratio of 1:4 Percholoric acidand Nitric acid and then were analyzed by atomic absorption spectrophotometry. Statisticalanalysis of all data was also done using SPSS 21 and various criteria were used to fine theamount of contamination of heavy metals.Results: The results showed that the average total concentration of Zn, Cu, Pb and Cr in thesummer were (48.16, 39.2, 14.45 and 10.35) and as for winter was (39.88, 26.93, 12.23 and10.301) mg/kg respectively. In addition, evaluating geo-accumulation indexes, pollution loadand pollution factor indicated the low pollution status of the area in both seasons.Conclusions: According to the results, pollution status and the RI level of heavy metals in theBashar River is low and similar in summer and winter. Also, the sources and changes inelements concentration in different stations and seasons may be as a result of the institution ofvarious urban and industrial contamination sources along the river, and its physical and geobiochemicalchanges in water flow volume entering the river, especially in winter.

Sediment Quality Index, Ecological Risk Assessment, Heavy Metals, Bashar River, Iran