Polycyclic aromatic hydrocarbons and trace metal elements in groundwater of abidjan (Southern Côte d'Ivoire): occurrence, contamination status and human health risk assessment

ABSTRACT Two side-by-side maps of the Abidjan District, Côte d'Ivoire, showing the 20 groundwater sampling points as coloured circles, with the Banco Forest in green and the lagoon in blue. The left map shows lead concentrations in two classes: lower values (0.000129–0.000190) in yellow and higher values (0.000191–0.001181) in red. The right map shows the health risk index for the adult population in four classes, from 0.060 to 0.642, with larger red circles for higher risk. Higher lead concentrations and higher risk values occur mainly at points in the northern communes (Abobo, Cocody, Adjamé, Yopougon) and near the lagoon in Treichville, Marcory and Koumassi. Groundwater is a major source of drinking water in Abidjan, Côte d'Ivoire, but its quality may be affected by rapid urbanization and industrial activities. This study assessed the occurrence of polycyclic aromatic hydrocarbons (PAHs) and trace metal elements (TMEs) in 20 groundwater collected from boreholes and wells. Trace metals were analyzed using ICP-OES, while PAHs were determined by GC-MS. The results showed that most trace metal concentrations, including Fe, Cu, Zn, and Pb, were generally below the World Health Organization (WHO) guideline values. However, several PAHs were detected in both wells and boreholes, with higher concentrations observed in shallow wells. The contamination degree (CD) indicated contamination levels ranging from low to high depending on the sampling location. Human health risk assessment revealed low noncarcinogenic risks through groundwater ingestion but higher risks associated with dermal exposure, particularly for children. Carcinogenic risks related to Pb and selected carcinogenic PAHs exceeded the acceptable limits recommended by the United States Environmental Protection Agency (USEPA) at several sites. The predominance of high-molecular-weight PAHs suggests a mainly pyrogenic origin linked to vehicular emissions, waste burning, urban activities, and industrial operations. Continuous groundwater monitoring and improved protection measures are therefore essential to safeguard public health.