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Marine ecosystems are threatened by numerous discharges of contaminants,mostly untreated sewage wastes and industrial effluents both which ultimately affect the sustainability of living resources.Clearly,these contaminants are known to pose public health risks worldwide.With upsurges of industrialization and urbanization,the input of heavy metals into coastal environments through rivers,runoff and land-based point sources has increased dramatically in the last two decades.Consequently,the water quality in these areas relates directly to the quality of sediments which serves as the final sink for these contaminants.Heavy metals can accumulate in these sediments and subsequently contaminate the water column and affect the benthic and pelagic flora and fauna.The semi-enclosed basin of Lagos Harbour is an area with restricted water circulation and typifies this situation.In Nigeria,most of the investigations on heavy metals are termed segmented studies.Coordinated investigations to determine the concentrations of these elements and their effects on the water and sediment qualities are lacking within the harbour system.Therefore,an investigation with respect to contamination from shipping activities,including dredging is desirable.The present study is investigating the geochemistry of a number of heavy metals(Cd,Pb,Cu,As,Cr,Zn)in the surficial sediments of Lagos Harbour and Lagos Lagoon,using a number of speciation methods and comparing the data with sediment quality guidelines to give an assessment of metal contamination.Twenty-six sampling stations were established at locations based on contaminant sources,contaminant types and anthropogenic activities.Surficial samples were collected during the wet(September 2013)and dry(February 2013 and 2014)seasons and are currently being processed and analysed using a number of speciation techniques.A two-phase trace metal acid digest speciation(Bioavailable and Extractable)scheme is being utilised along with a total metal technique using XRF.Interpretation of the metal concentrations are being undertaken using enrichment factors compared to OSPAR background assessment concentrations(BAC)and other published sediment quality guidelines to ascertain the extent of metal contamination within the Lagos lagoon.Metal contamination at each sampling site is also being assessed using ancillary data including total Al concentrations,particle size and organic carbon content.