Spatial Distribution, Contamination Characteristics and Eco-Risk Assessment of Toxic Metals in Stream Sediments of Njombe-Penja Banana Plain, Cameroon Volcanic Line

Toxic metals pollution of sediments is a global problem, especially in developing countries. Assessing toxic metals in sediments is crucial for maintaining ecosystem health. Hence, this study investigates the spatial distribution, pollution levels, and eco-risk of toxic metals in stream sediments of Njombe-Penja, Cameroon.

Sediment samples were analyzed by inductively coupled plasma-mass spectrometry.

The results highlight significant concentrations of Co, Cr, Cu, Hg, Ni, Pb, V, Zn, and Mn above the reference values. The correlation matrix indicates the presence of common input sources and similar geochemical characteristics of toxic metals. Spatial distribution maps show high concentrations of toxic metals in the northeastern part of the study area. Pollution indicators show that the Enrichment Factor (EF = 0.07–383.41) varied from moderate to severe enrichment of metals. The Contamination Degree (6 < C_deg < 24), Geo-accumulation Index (Igeo = 0.01–55.72), and Potential Ecological Risk Index (RI =  < 180) revealed a moderate to high degree of contamination. Most stations have Pollution Load Index, and Nemerow Integrated Pollution Index values greater than one, indicating pollution. Toxic Risk Index (TRI = 6.49–9.43), Sediment Quality Guidelines, and Modified Hazard Quotient (mHQ = 0.11–2.8) indicate moderate to very high toxicity risks of metals, suggesting significant toxicological effects of metals to biota and humans.

This study serves as an early warning about possible sediment contamination, metallic pollution, and toxicity risks of metals in the study area. Further studies are required to investigate the interactions of toxic metals between sediments and water and the associated environmental factors.