Abstract Sediment samples were obtained from points where drainage of effluents were discharge into the New Calabar River. The samples were collected for a period of four months and analyzed for heavy metals using atomic absorption spectrophotometer (AAS). The heavy metals examined were iron (Fe), manganese (Mn), lead (Pb), cadmium (Cd), nickel (Ni), chromium (Cr) and zinc (Zn). The result of the heavy metals showed that the mean values of the measured heavy metals were Fe (177.111±16.984mg/Kg), Mn (47.946±2.245mg/Kg), Pb (3.102±0.254mg/Kg), Cd (0.216±0.132mg/Kg), Ni (4.537±0.466mg/Kg), Cr 4.156±1.154mg/Kg) and Zn (2.298±1.009 mg/Kg). The results of the heavy metals were then analyzed using some pollution indices so as to determine their input sources and implication in the environment. Contamination factor examination results showed that the sediment is not polluted with any of the heavy metals, some of them were at the preliminary stage of contamination. Geochemical index assessment of the heavy metals showed uncontamination of sediment with heavy metals and further to it indicated a non-anthropogenic source of heavy metals, which more or less indicated natural sources of heavy metals in the sediment. Ecological risk factor assessment showed that the sediment heavy metals do not pose any risk to ecological existence of biomes. Enrichment factor analysis indicated that there was significant enrichment with Mn, Pb, Cr and Cu in the stations, very high enrichment with Ni in the stations, butthere was a range of significant enrichment to extremely high enrichments with Cd in the sediments at the sampled points. Therefore, the point of drainage discharge into the river should be adequately monitored to prevent excessive discharge of heavy metals.
Keywords Geochemical index, ecological risk, enrichment factor, heavy metals, sediment.