eng International Academy of Ecology and Environmental Sciences Proceedings of the International Academy of Ecology and Environmental Sciences 2220-8860 2015-9-1 5 3 89 96 1 article O. Rashki Ghaleno 1 2 M.H. Sayadi 1 2 M.R. Rezaei 1 2 Student of Department of Environmental Sciences, University of Birjand, Birjand, Iran Department of Environmental Sciences, University of Birjand, Birjand, Iran 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. http://www.iaees.org/publications/journals/piaees/articles/2015-5(3)/ecological-risk-assessment-of-heavy-metals.pdf heavy metal surface sediment ecological risk assessment concentration factor