natural and concentration factor distribution of heavy metals in sediments of chah nimeh reservoirs of sistan, iran

thechah nimeh reservoirs of sistan is as one of the main water sources of zabol city used for drinking, agriculture, industry and livestock purposes. this study aimed to determine the contribution of the natural and concentration factors of heavy metals such as cd, pb and cu in sediment of chah nimeh of sistan. the concentrations of heavy metals in surface sediments were studied in six stations during 2013. to determine the concentration of the heavy metals atomic absorption spectrometer (contr aa 700) was used. sequential extraction analysis  was applied based on the share of natural and concentration factor sources of heavy metals. sequential extraction analysis showed that a considerable part of the pb (63.67%), cd (55.17%) and cu (57.17%) were from natural sources. the highest concentrations of cd and pb were 0.81 and 5.57 mg kg-1, respectively, obtained in station one and the maximum cu concentration was observed in station five (37.8 mg kg-1), while the lowest concentration of cd, pb and cu were 0.34, 3.95 and 31.4 mg kg-1, respectively.