REVIEW OF HEAVY-METALS IN THE AFRICAN AQUATIC ENVIRONMENT

Data were compiled from selected heavy metal studies in both freshwate r and marine ecosystems from the major African subregions, Northern, W est and Central, Eastern, and Southern Africa. The concentrations of h eavy metals were compared between different environmental compartments (water, sediments, fauna, and flora), between the different African s ubregions and with data from other areas in the world. Despite the sca rcity of the existing information on Africa, some conclusions could be drawn: Metal concentrations in organisms were generally below WHO lim its except for some localized sites, mostly with increased lead levels . There were no significant differences between inland water and coast al animals, but shellfish had higher concentrations of most metals tha n finish. For aquatic plants the heavy metal levels were higher in inl and waters. Compared to more industrialized regions and with the excep tion of some hot-spot sites, the concentrations of heavy metals in Afr ican aquatic systems were low and close to natural background levels. Nevertheless, in view of the expected increase in urbanization and soc io-economic activities in Africa, sources and quantities of heavy meta l discharges to aquatic environments have to be identified. Also, poll ution control measures should be formulated in each country. (C) 1994 Academic Press, Inc.