Assessment of heavy metals and radionuclides (U and Th) contamination, and source identification of the Lékié Watershed sediments, Cameroon

Abstract

This study aims to assess the pollution levels and sources of heavy metals (Al, Mn, Co, Ni, Sc and V) and radionuclides (Th and U) in sediments of Lékié Watershed in Cameroon. Surface sediment samples were collected from 14 stations across different areas of the Lékié Watershed. The heavy metal and radionuclide analysis on sediments were carried out and pollution indices such as enrichment factor (EF), contamination factor (CF), degree of contamination (DC), pollution load index (PLI), potential ecological risk assessment and multivariate statistical methods were utilized to evaluate the degree of contamination and estimate the source of metals in the sediments of Lékié Watershed. The results show that the mean concentrations are lower than those of the upper continental crust (UCC) reference values except those of Mn, Co, Ni, and V. The values of EF varied from moderate to severe enrichments (from 4 to 44). The contamination factor (1 < CF < 3), potential ecological risk (<40) and degree of contamination (<8) revealed a low to moderate degree of contamination. The majority of stations have PLI > 1, indicating pollution. The application of multivariate analysis to these metallic elements reveals contaminations attributed to anthropogenic activities, including the release of domestic, artisanal mining, and industrial effluents, as well as natural sources originating from the leaching of local surrounding soils and geological factors. To mitigate more pollution in this watershed which is closed from urbanization, it is crucial for local authorities to implement wastewater treatment measures.