Rasheed Adetoro
Osun State University , Nigeria
Title: HEAVY METALS SPECIATION OF OSUN RIVER IN OSUN STATE NIGERIA
Biography
Biography: Rasheed Adetoro
Abstract
As a result of rapid urbanization of major towns in Osun State since its creation in 1991, the activities around the rivers have increased tremendously with little or no regard for environmentally sound practice. Total concentrations of Mn, Fe, Cu, Zn, Cr, Pb and Ni in sediments were determined using wet digestion and atomic absorption spectrophotometric methods (AAS). Speciation of the elements was carried out using a five sequential extraction method. Results obtained revealed that in osun river sediments the general trend in total metal concentration in the six sampling sites was: LC > UC > MC for Mn and Cd, UC > MC > LC for Cu, Zn and Pb, UC > MC >LC for Fe while LC >MC > UC for Cr. Ni was not detected in all the samples. Speciation studies showed the trend in the percentage concentration of the metals in osun sediments in exchangeable fraction to be Cd > Cu > Zn > Mn while Fe, Cr and Pb were not detected in this fraction. The carbonate fraction was: Cd > Cu > Zn > Mn > Fe while Cr and Pb were not detected in this fraction. Reducible fraction was: Zn > Mn > Pb > Fe > Cu >Cr while Cd was not detected. Organic fraction was: Mn > Cr > Cu > Zn while Fe, Cd and Pb were not detected. Residual fraction to be Cr > Fe > Cu > Pb > Zn > Mn > Cd. It is therefore recommended that; The high percentage of majority of metals i.e. Fe, Cu, Zn, Cr and Pb (except upper course) in residual fractions (non-bioavailable form) in all the sampling sites for Osun river showed that the sediments could not be used for construction works (bridges and buildings). The non-bioavailability of Fe, Cu, Zn, Cr and Pb (except upper course) posed a much lower risk to the water body in normal conditions because of their low mobility in the sediment environment.