Trace Metals Distribution and Contamination in the Surface Marine Sediments of Roro Bay in Lagos, Nigeria

This paper presents the investigation of distributi on and contamination of Zn, Cu, Cr, Cd and Pb in surface marine sediments of Roll on- Roll off (Roro) bay, Lagos, S outh-West, Nigeria. Sediment samples of about 20 cm deep from twenty (20) locations in the bay were collected; wet diges ted with aqua regia and analysed for trace metals, employing Atomic Absorption Spectrophotometer (AAS). The metal toxicity risk was assessed with the application of two d ifferent sediment quality guidelines (SQG) indices i.e. effect range low/effect range medium (ERL/ERM) and threshold effect level/probable effect level (TEL/PEL). The order of concentration was Cd 5.0, suggesting similar sou rces for the metals, while very weak correlations w ere observed between Cu and Zn, as well as in Pb and Zn. Results showed that metals contamination was mainly due to dockyard activities, atmospheric deposition and industrial e ffluent discharged.