CONTRIBUTION A LETUDE DE LA CONTAMINATION AUX ELEMENTS TRACES METALLIQUES (MN, CO, CU, PB, HG, NI, ZN) DOREOCHROMIS NILOTICUS ET CLARIAS GARIEPINUS DE LA RIVIERE YOLO (KINSHASA, RDC)

This 3-year study, was conducted from July to September during the following years 2019, 2020 and 2021. It aimed to determine the concentration of heavy metals (Mn, Co, Cu, Pb, Hg, Ni, Zn) in two fish species, namely Oreochromis niloticus(herbivore) and Clarias gariepinus (omnivore) from the Yolo River in Kinshasa (DRC), which receives , in addition to the urban effluents along its watercourse, all the effluents of the industrial Limete district discharged without any pre-treatment into the drains and main collector of the district which leads to the river, in order to assess the risks related by the chronic consumption of these fish species by the population of the city of Kinshasa.The study revealed the presence of seven (7) metallic trace elements (Cu, Pb, Fe, Cd, Zn and Hg) in two species of fish studied according to the level of the food chain: Oreochromis niloticus having a primary diet (herbivore) and Clarias gariepinus having a tertiary diet (omnivore).The results thus found reveal on the one hand that the Oreochromis niloticus (herbivorous) were less contaminated than the Clarias gariepinus (omnivorous) and on the other hand, the heads are more contaminated than the flesh. However, not knowing the age of these species, we used the size to distinguish the young from the adults and the results obtained indicate how much the adult fish accumulate more heavy metals compared to the juveniles.Consequently, the regular consumption of fish from the Yolo River exposes the population of the city of Kinshasa to metabolic disturbances (mutagenic, teratogenic effects) and fatal diseases such as cancer.