TRACE METALS IN SURFACE WATER AND SEDIMENTS OF LOWER NEW CALABAR RIVER, RIVERS STATE, NIGERIA

Abstract

The concentration of trace metals in surface water and sediments of lower New Calabar River was investigated. The results obtained showed that the trace metals Pb, Cd, Fe, Zn, Co and Cu occurred in both surface water and sediments. There was high distribution of the trace metals according to the sample locations attributed to both anthropogenic and natural resources. The concentration of trace metals in surface water followed the trend Fe > Zn > Co > Pb > Cd = Cu. In the sediment, the highest concentrations were obtained at sample location 5 for Zn (101.50 μg g^-1), Pb (15.00 μg g^-1), Cd (1.30 μg g^-1), Co (11.50 μg g^-1) and Cu (11.50 μg g^-1) and sample location 3 for Fe (10815.00 μg g^-1). The results of the different statistical indices used in this study which includes Exchange factor between water and sediment, Contamination/Pollution (C/P) index, geoaccumulation index (I_geo), contamination factor (CF) and the Pollution load Index (PLI) generally showed that; the trace metals were higher in the sediments than the surface water; the sediments were classified as being uncontaminated with respect to Pb, Zn and Cu, unpolluted to moderately polluted with respect to Cd and moderately polluted with respect to Fe.  Therefore, these results showed that the levels of trace metals in the sediment were above the permissible limits by World Health Organization.