Heavy Metals Contamination of an Aquatic Environment and Health Risks Assessment in Two Fish Species: Case of the Guessabo Lake, Western Côte d'Ivoire

Abstract

The purpose of this study was to evaluate the contamination by heavy metals and the health risks of the residents of a watershed of the Sassandra river. Water and fish samples were taken from Guessabo Lake during the dry season and the rainy season. The average Hg, Pb, Cd and Zn concentrations in the water samples decreased during the rainy season by 20.51%, 80%, 18, 26% and 61.4%, respectively. In contrast, the average concentrations of As, Cu, Mn and Fe increased by 10%, 84.3%, 48.98% and 11.45%, respectively. The concentrations of heavy metals in water samples follow the trend: Fe> Cu> Mn> Pb> As> Zn> Hg> Cd. All metals except Fe were within permitted limits for drinking water quality at all stations during both seasons. The increase of As, Mn and Fe in water samples during rainy season was inversely proportional to their covalent index. The average heavy metal pollution index (HPI) for each sampling station showed higher pollution at the G2 station. The average Heavy metal evaluation index (HEI) of dry season (28) decreased relatively after the rainy season (21). Pearson's analysis showed that cadmium correlates strongly with HPI (r = 0.896) and HEI (r = 0.95) and iron is also highly correlated with HPI (r = 0.961) and HEI (r = 0.999). The concentration of trace metals obtained in the muscles of Chrysichthys nigrodigitatus (demersal) and Tilapia spp (benthopelagic) showed that Tilapia spp concentrated more non-essential metals (Hg, Cd and As) than Chrysichthys nigrodigitatus. Human health risks of trace metals in fish muscle and water were low, but among the selected metals, As and Hg are the non-essential elements contributing more to the cumulative hazard quotient of HI (0.845) for children and (0.39) for adults.