Distributions of Trace Metals and Radionuclides Contamination in Alluvial Sediments from the Lobé River in Cameroon

The spatial and vertical distribution of heavy metals (Fe, Ni, Cr, Co, Sc and V) and radionuclides (Th and U) and the sediment characteristics of Lobé River, south–west Cameroon were assessed in this study to determine the possible source of pollutants and evaluate the level of pollution. Cores sediments were analyzed to measure grain size parameters, organic matter and geochemical composition. To understand the vertical distribution, tree strata were chosen (surface, middle and bottom). The main constituent of studied sediment is sand (82.06%). In these sediments, low content was recorded for organic matter (2.87%). The average concentration (mg/kg) of selected elements are in the order Fe (23,112.84) > Cr (447.62) > Ni (109.93) > V (47.04) > Th (23.70) > Co (7.74) > Sc (5.10) > U (2.78). The maximum concentration of most selected chemical elements was recorded in the middle, followed by surface and bottom, respectively. Enrichment factor (EF > 1.5), Geo-accumulation index (Igéo > 0) and contamination factor (CF > 1) revealed a moderate to severe pollution of Cr, Ni and Th in all strata. The pollution load index (PLI) show that surface and middle sediments (1.08 and 1.14, respectively) are polluted, while bottom sediments (0.88) are unpolluted. Pearson correlation, cluster analysis and component principal analysis confirmed that heavy metals (Fe, Sc, V, Cr, Ni and Co) have common anthropogenic sources where grain size parameters (sand, silt and clay) were associated with them while radionuclides (Th and U) have a natural source. The presence of human activities such as household wastes, intensive agriculture and the result of the processing of the industries products could be possible sources of the anthropogenic pollution, threatening for the environmental related issues in the region.