Abstract

Fish and periwinkles, from nine locations in the Lagos Lagoon, were processed and analysed for the presence of heavy metals (chromium Cr, manganese Mn, iron Fe, nickel Ni, copper Cu, zinc Zn, cadmium Cd and lead Pb) during the dry and wet seasons. Results showed that significant differences existed in the levels of metals in periwinkle and fish caught from the different locations while the influence of the period of sample collection on elemental levels indicated no significant difference in the levels of metals accumulated between the periods. Generally, the level sequence of the elements studied was, in most cases, similar in both locations and the period of sample collection for both periwinkle and fish. The sequence was different for periwinkle and fish: for periwinkle the sequence was Fe > Mn > Zn > Cd > Ni > Cu > Cr > Pb and for fish the sequence was Fe > Zn > Cd > Cu > Mn > Ni >Pb > Cr. The observed heavy metals concentrations in these organisms were below the recommended limits for human consumption.

Key words: Fish, periwinkle, heavy metals, cluster analysis, Lagos Lagoon.