Assessment of Ecological Hazard of Heavy Metals (Cr, Zn, Cu, Pb) in Surface Sediments of The Bashar River, Yasouj, Iran

Background & Aims of the Study: Heavy metals pollution in aquatic ecosystems threats living organisms' health and environment. Hence, the present study aims to assess concentration of lead, chromium, copper, zinc and their ecological risk in the surface sediments of the Bashar River during the summer and winter seasons. Materials & Methods: This is a field study; sampling of surface sediment was done in 8 stations in 2016. The samples were digested by the composition of ratio of 1:4 Percholoric acid and Nitric acid and then were analyzed by atomic absorption spectrophotometry. Statistical analysis of all data was also done using SPSS 21 and various criteria were used to fine the amount of contamination of heavy metals. Results: The results showed that the average total concentration of Zn, Cu, Pb and Cr in the summer were (48.16, 39.2, 14.45 and 10.35) and as for winter was (39.88, 26.93, 12.23 and 10.301) mg/kg respectively. In addition, evaluating geo-accumulation indexes, pollution load and 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 the Bashar River is low and similar in summer and winter. Also, the sources and changes in elements concentration in different stations and seasons may be as a result of the institution of various urban and industrial contamination sources along the river, and its physical and geo-biochemical changes in water flow volume entering the river, especially in winter.