O. Rashki Ghaleno M.H. Sayadi M.R. Rezaei Student of Department of Environmental Sciences, University of Birjand, Birjand, Iran Department of Environmental Sciences, University of Birjand, Birjand, Iran Proceedings of the International Academy of Ecology and Environmental Sciences ISSN 2220-8860 http://www.iaees.org/publications/journals/piaees/online-version.asp 2015 5 3 89 96 International Academy of Ecology and Environmental Sciences Hong Kong 9 April 2015 15 May 2015 1 September 2015 heavy metal surface sediment ecological risk assessment concentration factor The distributions of heavy metal concentrations in the surface sediments of Chah Nimeh of Sistan water reservoir were assessed. Sediment samples collected at 6 sites in the Chah Nimeh of Sistan water reservoir in connection with field surveys and the total concentrations were determined using atomic absorption spectrophotometry. The average contents of the metals studied were: Cd, 0.58 mg/kg; Pb, 4.76 mg/kg; and Cu, 42.41 mg/kg and arrangement of the metals from higher to lower mean content in this area are: Cu greater than Pb greater than Cd. The Igeo values were ranged from -2.7 to 1.8 with an average of -0.65. The pollution load index (PLI) ranged from 0.6 to 1.4, and the average index of PLI was 1.0, the Chah Nimeh of Sistan was moderately polluted. The index range of potential ecological risk was from 45.3 to 165.2, and the average index of potential ecological risk factors (RI) was 111.2. DOI 10.0000/issn-2220-8860-piaees-2015-v5-0011 http://www.iaees.org/publications/journals/piaees/articles/2015-5(3)/ecological-risk-assessment-of-heavy-metals.pdf