INFLUENCE OF THE WATER QUALITY OF LAKE TOHO LOCATED IN THE MONO DEPARTMENT, SOUTHWEST BENIN, BY GLYPHOSATE AND METALS (COPPER, ZINC, LEAD, CADMIUM)

In order to assess the pollution status of the waters in Lake Toho, water samples were collected and analyzed using the spectrophotometer. Researched elements such as glyphosate are in high concentrations in the lake waters. The same goes for Trace Metal Elements such as copper, zinc, lead, cadmium in the waters of the said lake. The metal contents are beyond the tolerable limit by the Canadian standard following the Criteria for the protection of Aquatic Life according to Chronic effects (CVAC: 0.0085 mg.L-1 for copper and lead, 0.11 mg.L-1 for zinc, 0.0093 mg.L-1 for cadmium). Likewise, the copper, zinc and lead contents (during the long dry season and end of the long rainy season) recorded exceed the same standard according to the Criteria for the protection of Aquatic Life according to Acute effects (CVAA: 0.012 mg.L-1 for copper, 0.11 mg.L-1 for zinc and 0.22 mg.L-1 for lead). These levels of herbicide and metals present would contribute to the toxicity of the waters of Lake Toho and constitute a green threat for the aquatic organisms present in the said lake. It is urgent to put in place a management and control system for actions around the lake.