A Baseline Study of Trace Metals in Marine Organisms from Ghana, West Africa

by Charles A. Biney, Inst of Aquatic Biology, Achimota, Ghana,

Document Type: Proceeding Paper

Part of: Coastal Zone '91


As part of the Joint FAO/IOC/WHO/IAEA/UNEP Project on monitoring of pollution in the marine environment of the West and Central African region, 279 samples representing 17 families and 27 species of marine biota from the coast of Ghana were analysed for Hg, Cd, Pb, Cu, Zn, Mn and Fe between 1985 and 1989. The levels of trace metals in all groups were below or comparable with the WHO limits for food. Cd and Mn for example were not detected in fillets. Hg concentrations ranged from <0.01 in Mugilidae to 0.15 ?g?g-1 fresh weight in Balistidae with an overall mean for marine biota of 0.062 ? 0.032 ?g?g-1. Generally, there was not much variation in Hg concentrations between the different groups. Pb concentrations were also low with mean values ranging from <0.02 ?g?g-1 in Mugilidae, Cynoglossidae and Cichlidae to 0.82 ?g?g-1 in Penaeidae. Just as for Pb, the lowest concentrations of Cu and Zn occurred in Mugilidae and the highest in shellfishes. In relation to the other elements, Fe was detected in relatively high concentrations. While the concentrations of trace metals were of the same range as for other West and Central African countries, Hg was low compared to the Mediterranean region. The occurrence of trace metals in different tissues was found to be: Bone > Liver > Ovary > Gills > Heart = Spleen = Kidney > Skin > Fillet. Despite the generally low levels of trace metals, the need to formulate control measures by focussing on areas close to sources of inputs is stressed.

Subject Headings: Water pollution | Developing countries | Zinc | Organisms | Wildlife | Trace elements | Seas and oceans | Africa | Ghana

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