Assessment of Pre-Dregding levels of Heavy Metal Pollution in Sediments of Otamiri River, IMO State of Nigeria

摘要

The distribution, controlling geochemical factors and contamination status of heavy metals in sediments of Otamiri River in Owerri, Imo State of Nigeria, were investigated. Two groups of bed sediments samples were collected from three sites during February 2008 and June 2008. The samples were analyzed to determine their heavy metals (Cd, Pb, Ni, Zn, Cu, Fe and Cr), pH and Total organic carbon (TOC %) content. The results showed that the heavy metal concentrations were slightly higher in February than those sampled in June. The results also showed that metal content are directly correlated to TOC%. Environmental assessment of sediments pollution by heavy metal was carried out using geo-accumulation index (I_(geo)) and comparison with Canadian, Dutch and German targets for sediment quality Guidelines. The results indicated that natural processes such as weathering and erosion of bedrock are the main supply sources of heavy metals in sediments of Otamiri Rivers near Owerri, as the sediments were noted to be in unpolluted or excellent state.