DETERMINATION OF HEAVY METAL POLLUTANT IN FLOODPLAIN SOILS OF THE LOWER REACHES OF RIVER NIGER, ASABA AXIS, DELTA STATE, NIGERIA.

Abstract

This project is to determine the concentration of Heavy metals in soils samples from flooded plains
in Delta state within some extent of the River Niger which Stretched from Asaba to Aboh Area,
Nigeria. Pollution of the natural environment by heavy metals is a universal problem because
these metals are indestructible and most of them have toxic effects on living organisms, when
permissible concentration levels are exceeded (Mmolawa et al.,2011) Flooding significantly
influenced the contamination of floodplain soils and as well as redistribution of anthropogenic
contaminants due to the processes of erosion and sedimentations in floodplains (Tesi et al., 2016;
Iwegbue et al., 2020). The soil sample was digested with aqua-regia, and the samples were
subsequently analyzed for Fe, Mn, Zn, Cu, Pb, Cd, Cr, Co, and Ni using using atomic adsorption
spectrometry (AAS) (Perkin Elmer Analyst 200 Shelton CT, USA). The results of the
concentrations, contamination/pollution index for metals in the Floodplain Soils of the Lower
Reaches of River Niger, Asaba, Delta state, Nigeria were obtained in all sites and depths which
ranged from 0.63 to 67.6 mg kg-1 for Mn, 15.8 to 31.6 mg kg-1 for Ni, 4044 to 8403 mg kg-1 for
Fe, 0.63 to 48.8 mg kg-1 for Cr, 4.3 to 13.4 mg kg-1 for Cu, 4.35 to 28.2 mg kg-1 for Zn, 1.10 to
4.80 mg kg-1 for Cd and 17.1 to 41.3 mg kg-1 for Pb. The concentrations of metals at these sites
were below the Department of Petroleum Resources target values for metals in soils except for
Cadmium (Cd) and Iron(Fe) in some sites. A significant fraction of these metals arose from
anthropogenic sources. The percent anthropogenic fraction of metals in the soil follow the order of
pollution as Cd > Fe > Pb > Cr > Ni > Cu > Mn > Zn. In conclusion, it is a project which is
intended at providing Knowledge of the levels of these toxic pollutants in soils which is necessary
in outlining areas that have exceeded vulnerability level and to evaluate both ecological and
human health risk. It is recommended that, the information provided should be useful for
surveillance program, urban environmental quality managements and risk minimization.