Increased knowledge about the nutrient content of biological or...

In this study accumulation of nine heavy metals (Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, and Zn) were evaluated in water, bottom sediment and muscle and bone tissues of three fish species (Labeobarbus spp, Clarias gariepinus and Oreochromis niloticus) collected from Tekeze River, Dam in Tigray, Northern Ethiopia. Samples were analyzed using Varian AA240 FS Fast Sequential Atomic Absorption Photometry. The mean contents of metal, expressed in mg/kg dry weight, varied from 1.33 to 8.42 for Co, 0.34 to 1.68 for Cd, 0.64 to 5.15 for Cr, 1.09 to 2.76 for Cu, 1.44 to 2.12 for Pb, 23.88 to 126.29 for Zn, 0.38 to 1.07 for Ni, 31.58 to 90.92 for Fe and 1.36 to 21.49 for Mn. Results showed that the highest and lowest contents of heavy metals in muscle and bone of both fish samples were related to Zn and Ni concentration, respectively, and heavy metal contents in bone and muscle samples were found to decrease in sequence as Zn>Fe>Mn>Co>Cr>Cu>Pb>Cd>Ni. Similarly the order of the concentration of the heavy metals in water and sediment samples were as follows: Zn>Co>Fe>Ni>Cr>Pb>Cu>Cd>Mn an