Distribution of Heavy metals in sediments and surface waters from Iko River Marine Ecosystems, Akwa Ibom State, Niger Delta, Nigeria

Abstract

 There have been intense crude oil and gas exploration and production activities within the Atlantic coastline of Iko River marine ecosystems, Akwa Ibom State, Nigeria, which has been on for decades, with new investments in the Oil Mining License Field 13 (OML 13) with consequent load of heavy metals. This study aims to determine the seasonal and spatial distribution of the levels of heavy metals in the sediments and surface waters of the Iko River marine ecosystem. The present study presents an opportunity to generate relevant data  heavy metals distribution, pollution status, and their associated risks in these ecosystems. The heavy metals considered are cadmium (Cd), lead (Pb), zinc (Zn),  vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu), will be determined by inductively coupled plasma (Agilent 720 ICP-OES)  spectrometer, in sediments and surface waters from five (5) sampling locations ( L1 – L5). The modified degree of contamination index, mC_d, in sediment for both dry and rainy seasons, indicated that L1 has the lowest contamination status (0.59 - 0.75), while, L5  has a high degree of contamination (3.76 – 4.07). Also,  L5 indicated a very high contamination status for concerning Zn (7.84 – 9.01) in both seasons.. All the heavy metals of concern in this study have low potential ecological risk ( maximum Ri = 20.44 ), in the sediments compared to the reference values  (Eⁱ_f < 40, and Ri < 150) at all the sampling sites in both seasons.