ENVIRONMENTAL RISK ASSESSMENT OF HEAVY METALS CONTAMINATION IN THE SEDIMENT OF MANDALI DAM RESERVOIR EASTERN IRAQ

      A study has been conducted to quantify the heavy metals concentration as well as the spatial distribution of heavy metals in sediments of the reservoir Mandali dam in the eastern part of Iraq. Three samples of sediments (A, B, and C) have been collected from the Mandali dam reservoir to study the ecological risk assessment of Co, Ni,Cu, Zn, Mo, Cd, Pb, Fe and U  in order to assess their toxicity by using different pollution indices. The average concentration of heavy metals of CO, Ni ,Cu Zn, Mo , Pb, Fe, U. are 22.9ppm, 89.3ppm, 16.3ppm, 48.3 ppm 3.6 ppm, 1.2ppm, 11604ppm and 20ppm respectively. The contamination level in sediments was assessed with the use of the Contamination factor (CF), Contamination of degree (CD),  Enrichment factor (EF), Geo-accumulation index (Igeo ), and Sediment pollution index (SPI). The highest values of the enrichment factor for the elements is  Pb, U  that ranged between  7.05to 8.23and from 291 to 331 respectively, and EF for Cd, and U elements is 26.56 to 38.49, 28.63to30.23 respectively, the Igeo is 2.00 to 2.80 and  2.27to 3.52 for Cd, and  U elements respectively,  The SPI ranged between 7.43 to 8.58. The heavy metals accumulated in the Mandali Dam reservoir sediments may have resulted from industrial activities, and natural processes by means of erosion and natural water flow.