Potentially toxic elements source identification and associated health risks in the groundwater of transboundary Komadugu-Yobe basin, Lake Chad region: An integrated approach using chemometric analysis and index-based models

Transboundary Komadugu-Yobe basin, located in the semi-arid to arid region of Nigeria and Niger Republic, is a vital water resource supporting domestic, agricultural, and industrial activities. This study investigates the pollution levels, potential sources, and human health risks associated with potentially toxic elements (PTEs) in groundwater using an integrated approach combining index-based models and chemometric analysis. The results indicate that Pb, Fe, Mn, and Cd are the key contaminants, with no significant seasonal variations. Pollution indices (Cdeg, HEI, HPI, and mHPI) classify groundwater as less polluted in upgradient areas and highly polluted in downgradient zones. Human health risk assessment (HHRA) reveals significant non-carcinogenic and carcinogenic risks (mean HI > 1 for both adults and children; mean CR > 1.0 × 10⁻³ for adults, and > 1.0 × 10⁻⁴ for children). As, Cd, Mn, and Pb are key the contributors to non-carcinogenic and carcinogenic health risks and potential risks of chronic kidney disease of unknown aetiology (CKDu). Correlation analysis suggests distinct geochemical behaviours of PTEs. Principal Component Analysis/Factor Analysis (PCA/FA) and R-mode Hierarchical Cluster Analysis (HCA) identify mixed sources, including industrial and domestic discharges as well as agricultural activities, as major contributors to groundwater contamination. These findings provide critical insights for policymakers, stakeholders and regulatory institutions to develop effective strategies for sustainable groundwater resource management in the region. • There is evidence of groundwater contamination with PTEs (Pb, Fe, Mn, and Cd). • Chemometric analysis was employed to distinguish various sources of PTEs contamination. • Pollution indices indicate higher groundwater contamination in downgradient areas. • Significant carcinogenic (CR) and non-carcinogenic (NCR) health risks were identified for both adults and children.