Distribution of Cobalt and Nickle in plankton and it s aquatic surround habitats in Euphrates and Al-Garaf rivers at Al-Nassiria city, southern of Iraq

The study was carried out to investigate the distribution of concentrations two heavy metals Cobalt (Co) and Nickle (Ni) [as heavy metals] in plankton (phytoplankton and zooplankton) and in its surrounded habitats(water, sediment and aquatic plants) in two rivers (Euphrates and Al-Garaf) at Al-Nassiria city ,southern of Iraq, for one year (January-December,2004) . Results showed considerable seasonal variations in the concentrations of these two metals. Ni concentration in plankton and aquatic plants were found to be greater than that of Co in both rivers, while the concentration factor (plankton /water) and (aquatic plants /water) for Ni was greater than for Co in both rivers.