Contamination and ecological risk assessment of As, Cr, Cu, Ni, Pb and Zn in surface sediments of Khiav River, Sabalan geothermal area, NW of Iran

In this research potentially toxic elements (As, Cr, Cu, Ni, Pb and Zn) concentrations were studied to investigate their contamination and ecological effects in surface sediments of Khive River. The sediment samples were collected along the river, betwee Sabalan geothermal power plant to Meshkin Shahr. The measured concentrations with sediment quality guidelines reveal that As, Cr and Pb concentrations were above the probable effect level (PEL) in 23%, 15.38% and 7.69% of the sediment samples, respectively. Also the results show that As, Cr, Cu, Ni and Zn were between TEL and PEL for 30.77%, 61.54%, 100%, 100% and 23.08% of the sediment samples, respectively, indicating that the concentration of these elements were likely to occasionally exhibit an adverse effects on the ecosystem. Results of enrichment factor (EF) calculations based on local background showed moderate to high enrichment for as in sediment samples. Zinc, Cr, Cu, Ni and Pb concentrations indicated low to moderate enrichment in sediments. The results of evaluation on potential ecological risk factor (PER) showed high risk for As. The calculated risk index (RI) values of the present sediments indicated low risk. Arsenic enrichment in sediments of Khiav River suggests different sources such as Sabalan geothermal power plant, spa complexes, thermal springs and mining activity. Therefore, management decisions for mitigation practices in Khiav River should be preferably focused on arsenic contamination.