Geospatial distribution of hazardous metals and other elements in stream sediments of Akum, Cameroon: Insights into mineral exploration and ecosystem health using indexical and multivariate approaches

Abstract

This study investigates base metal mineralisation possibilities, pollution, toxicity and human health risk of hazardous metals (HMs) in stream sediments of Akum, Cameroon. This area lacks base metal assessment despite growing concerns about metal enrichment and pollution in an area of sand mining, urbanisation, and unusual semi-precious stone recovery, although in low quantities. Fifteen sediment samples (15–25 cm) were digested and analysed by inductively coupled plasma-mass spectrometry (ICP-MS); contamination and risk were evaluated using pollution and health risk indices. The mean concentrations of As, Cd, Mo, Pb, Sn and Zn surpassed upper continental crust values, suggesting base metal anomalies having implications for mineral exploration. The kurtosis findings indicate platykurtic to leptokurtic distribution pattern of elements. The concentration of Cr, As, Cd and Zn were above the benchmark limits, indicating toxic stress responses to benthic organisms in the ecosystem. Pollution parameters (CF: 0.005–9.410; Cdeg: 16.60–52.09; PLI: 0.480–1.543; EF: 0.151–9.235) suggest moderate to high contamination levels in sediments. Ecological risk assessment (Er: 0.126–22.814; RI: 20.382–51.193) and toxicity indices (TRI: 3.662–8.068; TUs: 1.916–4.595) indicate low potential ecological risk and toxicity impact of HMs. Health risk assessments (THI, and TCR) are within the acceptable threshold limits (THI < 1; TCR: 1 × 10⁻⁴ and 1 × 10⁻⁶), suggesting minimal risks to human health. According to the Pearson correlation coefficient (PCC), principal component analysis (PCA) and dual hierarchical cluster analysis (HCA), most HM are primarily derived from lithogenic sources. In addition, Cd, As, Pb and Sn had strong anthropogenic signals and lithogenic contributions. This study highlights important concentrations of some elements above upper continental crust values that prove profitable for future mineral exploration ventures. These findings highlight the need for targeted monitoring and management strategies to mitigate health and ecological risks in these vulnerable sediment environments based on growing anthropogenic pressure on aquatic ecosystems.