Water quality evaluation from Lomé’s lagoon: Effects on heavy metals contamination on fishes.

The relevance of this study shows that in general, water of lake of Lome has a strong alkalinity (pH raging from 8.8-9.2) and a strong salinity revealed by the high value of the electric conductivity (2800-3200 μs.cm^-1). An impressive algae colony is composing the essential suspended matter (60-70 mg.l^-1). The water turbidity was about 80-90 NTU. We also determined that in some places of the lake, the high concentration of nitrogen compounds appeared to be the major causing pollution since the NTK (total nitrogen) ranged from 20-22 mgN.l^-1. In contrast, the COD (chemical oxygen demand) and the BOD (biochemical oxygen demand) values were low (110 mgO2.l^-1 and 40 mgO2.l^-1 respectively). In the case of metallic elements, cadmium contents was very low in water, sediments and fishes. Copper, lead, zinc and mercury concentrations in water were respectively 3.6; 8.0; 7.0 and 14.0μg.l^-1. In fishes, the following measured values of the same elements were 5.0; 2.8; 20.2 and 5.5 μg.l^-1 respectively.