Heavy Metals Pollution Level in Water, Fish and Sediments from the Logone River Within Moundou City (Chad)

Abstract

The evaluation of metal pollution level of Logone River at Moundou (Chad) was done by measuring the amount of Iron (Fe), Copper (Cu), Manganese (Mn), Chromium (Cr), Cadmium (Cd) and lead (Pb). The water, sediments and fish samples were collected around the river at 4 sites and the concentrations were determined by spectrophotometric UV-Visible analyses. The results obtained showed that iron (Fe) had the highest concentration in water with average of 0.77±0.03mg/L followed by Mn (0.13±0.01 mg/L). In contrast, in the sediments Mn had a highest concentration followed by Fe with an average content of 33.17±0.04mg/kg and 7.61±0.02mg/kg respectively. In both cases, Cd had the lowest concentration of 0.52±0.03µg/kg and 0.43±0.02µg/L in the sediment and water respectively. The lowest values of enrichment factor (0-0.88) and average contamination indexes (0.74 to 0.88) indicates that the sediment are not polluted by As, Cd, Cr and Pb. However, Mn is highly found in sediment with an EF of 76.88% and 100% at AM and COT sampling site respectively at which suggest the origin of this heavy metal by Coton tchad activities. The values of bioconcentration factor (BCF) of Cd, Cr, Fe and Mn proved that the fishes are under bioaccumulation step. This study proved that the various waste generated by industries (CotonTchad and Brewery of Chad) and agriculture practices at Moundou affect significantly the quality of Logone River ecosystem.

Heavy Metals Pollution in Water, Sediments and Fish of Léré Lake, Western Mayo Kebbi (Chad)

“…These results show that lead concentrations were widely higher than those fixed by WHO (0.05 mg/l). They were in any case higher than those obtained by [44] but lower than the data of [21]. Lead is a toxic element, very dangerous for the human organism.…”

“…Three flasks were thus filled with water at each sampling point. Water samples collected were preserved at 4°C in icebox and conveyed immediately to the laboratory where they were submitted to a pre-treatment before analysis [44].…”

“…Thereafter, the fish samples were submitted to the following pretreatment: for each fish, the gills and flesh were separated and introduced into the drying oven, then in the furnace where they were reduced in ash in accordance with the method indicated by [3] and [1]. From ashes were obtained solutions containing heavy metals of which concentration could be determined [44].…”

“…The method consisted to sample surface sediments up to 20 cm depth using a new shovel (having a plastic sleeve) on board of a barque. The samples were collected in new plastic bags, mixed until obtaining a homogeneous mixture, then preserved in an icebox at 4°C and conveyed to the laboratory where they underwent a treatment before analysis [44].…”

“…Other results were exposed in the literature: 33 mg/kg for the Tanganyika lake [19], 11.2 mg/kg for the Mariout lake in Egypt [40], 3.8 mg/kg for the Kpong basin in Ghana [10], 4.65 mg/kg for the Victoria lake in Kenya [45] and6.53 mg/kg for the Logone river in Chad [44].…”