Distribution of trace metals and radionuclides contamination in two sections of sediment cores from the Nyong estuary, Cameroon, southern Atlantic coast

Abstract

This study investigated the spatial distribution of trace metals (Fe, Mn, Ni, Cr, Co, Sc and V) and radionuclides (Th and U) contamination in surface and bottom sediments from the Nyong estuary, Cameroon southern Atlantic coast, to provide informations on the pollution status of these sediments and the possible sources of pollutants. Salinity were measured in situ in interstitial water and dried sediment were analyzed for grain size parameters and geochemical composition. Salinity decreases from downstream to upstream, with 19.88 PSU as the highest value and sand is the main constituent (79.25 %). The concentrations of these elements varied significantly among depth (surface and bottom section), with a preferential contribution from the surface. In this surface section, several elements (Fe, Mn, Co, Sc and V) contributed about 80 % to the distribution of each of them in the estuary. Enrichment Factor (EF), Geo-accumulation Index (Igeo) and Contamination Factor (CF) of Nyong estuary surface sediments revealed a moderate pollution, while bottom sediment were unpolluted to moderate polluted. The pollution load index (PLI) show that surface sediments (3.86) and bottom sediments (1.19) are polluted. Pearson correlation and component principal analysis confirmed the natural origin of selected elements (Fe, Mn, Ni, Cr, Co, Sc, V, Th and U) through the weathering and the erosion of sources rocks. However, Pearson correlation analysis and the high Ni (3.91) and Cr (3.54) EF values in bottom sediments suggest a reception of other contaminants from the same emission sources or similar sources, may be agronomic inputs.