Abstract:
The study was conducated in Benya and Nakwa lagoons in the Central Region of Ghana, to
assess the level of heavy metal pollution of the water and its sediment, as well as in two species
of fish: the black chin tilapia (Sarotherodon melanotheron) and oyster (Crassostrea tulipa) both
of which constitute one of the major sources of protein for the local people of Elmina and
Nakwa. It was also to find out the effect of cooking and depuration (of oysters) on the heavy
metal content of the biota. The method involves collection of samples of the species with cast
net, scaled and gutted. But the oyster samples were hand–picked. Each sample was divided into
two, weighing 500 g. each. One portion was boiled and the other part was dried to a constant
weight. The oyster sample was similarly treated. The oyster sample was divided into two, one
depurated and the other half not depurated. Water and sediment samples from the lagoons were
also collected for analysis at WRI of CSIR.. The results indicated that cooking significantly
reduced the concentration of Pb in Crassostrea tulipa from Nakwa but increased concentration
of Cd, Pb. As and Hg in S. melanotheron, significantly. Depuration significantly reduced As and
Cd concentration in C. tulipa from Benya, but raised the concentration of Pb and Hg in C. tulipa
from Benya.
