Polymetallic Contamination Assessment of Lake San-Pedro: Characterization by ICP-MS and Heavy Metal Pollution Index (HPI)

Heavy metal contamination of aquatic ecosystems is a major environmental and public health issue, particularly in rapidly urbanizing regions of developing countries. This study assessed the polymetallic pollution of Lake San-Pedro (Côte d’Ivoire) during the rainy season, focusing on the spatial distribution and severity of contamination. A total of 12 surface water samples—three point samples per station—were collected from four stations selected based on their exposure to industrial, domestic, and urban discharges. Samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of nine heavy metals. Key physicochemical parameters were also measured, and the Heavy Metal Pollution Index (HPI) was applied to quantify the overall contamination level. The results revealed elevated concentrations of iron (1.10-1.93 mg/L), aluminum (0.36-1.33 mg/L), and nickel (0.03-0.38 mg/L), all significantly exceeding World Health Organization (WHO) guidelines. HPI values at all stations were well above the critical threshold of 100, indicating severe heavy metal pollution. High turbidity and elevated organic loads were observed across several sites, suggesting substantial degradation of water quality. Statistical analysis (one-way ANOVA) confirmed significant spatial differences (p < 0.05) in the concentrations of Al, Fe, Ni, Pb, and Cr, with stations 1 and 2—located near major anthropogenic activities—showing the highest contamination levels. These findings highlight the urgent need for integrated watershed management measures, including wastewater treatment, pollution source control, and routine monitoring of water quality. This study provides key data to support the protection and sustainable use of Lake San-Pedro’s aquatic resources.