Mapping and Descriptive Analysis of Surface Sediments at the Mouth of the Sassandra River (Southwest Côte d’Ivoire)

Abstract

The mouth of the Sassandra River (Southwestern Côte d’Ivoire) is a transitional zone influenced by both fluvial and tidal currents. Although previous studies have focused on sediment mapping, the geochemical characteristics of this area remain poorly documented. This study aims to characterize the textural and geochemical properties of surface sediments and to better understand their spatial variability. Twenty surface sediment samples were collected using a hand-operated Van Veen grab. Laboratory analyses included grain-size measurements following standard sedimentological procedures, X-ray fluorescence (XRF) for major and trace element composition, and scanning electron microscopy (SEM) for microstructural observations. The results reveal coarse sands upstream, coarse to medium sands within the main channel, predominantly medium to fine sands near the river mouth, muddy sediments around the island, and mixed sand-mud deposits in the northern estuarine branch. The sands are angular to sub-angular, displaying cracks and fractures, and are coated with chemical elements such as Si, Fe, Al, Na, P, Ca, K, and Mg. Carbonates and rare earth elements occur in very low concentrations. The integration of sedimentological and geochemical data provides essential insights into sediment provenance and depositional dynamics. Nevertheless, long-term monitoring of sediment fluxes is required to fully understand the sedimentary infill processes operating at the Sassandra River mouth.