Bioaccumulation of heavy metals in Mbaa River and the impact on aquatic ecosystem.

The bioaccumulation and toxic effects of heavy metals have caused ecological damage to aquatic ecosystem. In this study, concentration of heavy metals including zinc, lead, cadmium, iron, and copper were determined in the sediment and water as well as in the muscle, gill, and intestine of two fish species (Pelmatochromis guentheri and Pelmatochromis pulcher) of Mbaa River in Southeastern Nigeria. Samples were collected at three different spots from the river, and the level of heavy metals specified above were determined by atomic absorption spectroscopy (AAS) after a modified wet digestion process. The results indicated that sediment had the highest concentration of the heavy metals investigated while water had the lowest concentration. Fish tissues showed appreciable bioaccumulation of these metals as evidenced by a higher concentration profile when compared with that of water. Furthermore, the concentration of these heavy metals in water and their bioconcentration factor in the fish were above the recommended limit by WHO and FEPA, indicating that Mbaa River along Inyishi may not be suitable for drinking nor the fish safe for human consumption. The study also reveals the use of fish as bioindicator of aquatic environment.

Biochemical changes during fermentation ofTelfairia seeds forogiri production.

Amylase activity increased during the fermentation of fluted pumpkin seeds forogiri production with corresponding decreases in amounts of total carbohydrates and soluble sugars. Sugars present were glucose, fructose, sucrose and an unidentified one. Protease also increased in activity during the termentation, giving higher amounts of free amino acids and a concomitant decrease in the total nitrogen of the seeds. Lipase activity was, however, minimal in the fermenting seeds.