Comparative studies of trace metals in lagoon snail, black-chin tilapia and water in the Brenu lagoon of Ghana
Concentrations of copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb) and mercury (Hg) in tilapia, lagoon snail (tissue and shell) and water from the Brenu Lagoon in the Central Region of the Republic of Ghana have been measured in this study. The results of the study are as follows; for tilapia, the concentrations of Zn, Cu, Cd, Pb and Hg are: 1038.8 µg/kg, 667.0 µg/kg, 0.200 µg/kg, 0.500 µg/kg and 2.113 µg/kg respectively, whereas the concentrations for Zn, Cu, Cd, Pb and Hg in the tissues in lagoon snail are: 805.3 µg/kg, 870.5 µg/kg, 2.500 µg/kg, 19.50 µg/kg and 4.142 µg/kg respectively. Similarly, Zn, Cu, Cd, Pb and Hg concentrations in the shells of snail obtained from the Brenu Lagoon are: 576.8 µg/kg, 449.3 µg/kg, 5.500 µg/kg, 0.500 µg/kg and 4.990 µg/kg, respectively. The concentrations of Zn, Cu, Cd, Pb and Hg in the water from the lagoon are: 144.9 µg/L, 111.7 µg/L, 0.750 µg/L, 4.5 µg/L and 2.761 µg/L respectively. Comparing the result with that of the World Bank Health Safety Guidelines of 300 µg/kg, 1000 µg/kg, 600 µg/kg, 100 µg/kg and 2.0 µg/kg for Cu, Zn, Pb, Cd and Hg respectively, all the samples except water had values above the limit for Cu and Hg. However the black-chin tilapia had higher Zn content than the acceptable levels. The level of mercury pollution is alarming and therefore effort should be made to stop further additions.