Determination of Source and Control Factors of Trace Metals (Cd, Zn, Cu, Cr, Ni and Pb) Bioaccumulation in Tilapia Fish of the Ebrié Lagoon (Côte d’Ivoire)

Abstract

Lagoon water as sources of trace metals contamination in Tilapia fish as well as the physico-chemical parameters controlling the bioaccumulation of trace metals were determined in the Ebrié lagoon. For this, trace metals contents (Cd, Zn, Cu, Cr, Ni and Pb) were measured in the water, sediments and flesh of the tilapia fish of the Ebrié lagoon. In addition, physico-chemical parameters (pH, salinity, dissolved oxygen and redox potential) were determined in the lagoon waters during two hydrological seasons: the dry season and the rainy season. The results obtained showed that the sediments of the Ebrié lagoon constituted a real trap for the studied trace metals (very high Rd). The bioaccumulation factors (BAFs) of all trace metals in lagoon water column were higher than those of the sediments, reflecting an intense bioaccumulation, from the water column (BAF water > 1> BAF sed). However for Cd, the BAF water and BAF sed values were less than 1. Zn was the most bioaccumulated metal in fish, while the lowest bioaccumulated Cd. The decrease in dissolved oxygen favored the increase of Cr contents in tilapias and the retention of Zn in sediments. The increase of the pH as well as the decrease of the redox potential had led to the decrease of the Ni contents in the Tilapias. Nevertheless, the fish flesh Tilapias of the lagoon Ebrié, was not toxic to consumers.