Abstract:
The Weija Lake, formed from the Densu River, presently one of the
most polluted rivers in Ghana, is a domestic source of Tilapia and Catfish.
This study determined the concentration of V, Mn, As, Hg, Cd, and Al in the
muscles of Tilapia zillii, Clarias gariepinus, Sarotherodon galilea, and
Oreochromis niloticus from the Weija Lake using Instrumental Neutron
Activation Analysis. The relationships between metal concentrations in fish
muscles on one hand, and fish length and weight, condition factor (Kf), and
metal concentrations in the water on the other hand were also determined.
All four fish species showed negative allometric growth. Kf correlated
negatively with V, Mn and Al concentrations in T. zilli, and positively with
V, Mn and Al concentrations in C. gariepinus, O. niloticus and S. galilea.
Fish lengths and weights correlated negatively with V, Mn and Al
concentrations in fish, with no significant correlation with As, Hg and Cd
levels. Metal concentrations in water correlated positively with
concentrations in fish. The Estimated Average Daily Doses from
consumption of fish from the lake were 6113µg - 33778.5µg V, 114,098.2µg
- 530,371µg Al, and 34,383.6µg - 129492µg Mn respectively, and these
exceeded the recommended ADIs of <1800µg V, 142.8µg Al, and 11,000µg
Mn respectively. The results indicate safe levels of Arsenic, Mercury, and
Cadmium, and unsafe levels of Vanadium, Aluminium and Manganese in T.
zillii, C. gariepinus, S. galilea, and O. niloticus from the lake.
