Heavy Metal Contamination and Sediment Quality in the Niger River: A Multi-Index Approach

Abstract

Sediment quality serves as a critical indicator for evaluating pollution levels in aquatic environments. This study assessed the concentrations of heavy metals (Cu, Cd, Fe, Mn, Pb, Zn) and sediment quality in the Niger River at two locations: Agenebode and Illushi. Results indicated that the concentrations of Cu, Fe, Mn, and Zn were generally higher in sediments from Agenebode compared to Illushi and followed the order: Fe > Zn > Cu > Mn > Cd > Pb, with mean concentrations exceeding sediment quality guidelines established by USEPA for most metals, except Zn at Illushi and Mn/Pb at both sites. The contamination factor (CF) revealed moderate contamination for Cd at Agenebode and Illushi, Pb at Agenebode, and Mn at Illushi (1 ≤ CF < 3), while other metals showed CF values below 1, indicating low contamination. Pollution Load Index (PLI) values were below 1 across both sites, signifying no overall metal pollution, while geo-accumulation index (Igeo) for Cd, Cu, Fe, Mn, Pb, and Zn ranged between 0 and 1, indicating no contamination, with specific Igeo values of -3.6910 at Agenebode and -3.6288 at Illushi. The mean Igeo ranking of heavy metal pollution was Pb > Cd > Fe > Cu > Mn > Zn at Agenebode and Mn > Cd > Zn > Fe > Cu > Pb at Illushi, while the individual ecological risk (Er) and the potential ecological risk index (PERI) suggested low ecological risk for heavy metals at both study sites. The river plays a vital role as a livelihood source for surrounding communities, ensuring the quality of its water and sediments is essential. Continuous monitoring and assessment of heavy metal contamination is recommended to effectively evaluate ecological risks and guide pollution management strategies for the Niger River.