Assessment of heavy metal contamination and its ecological risks in the surface sediments along the lower part of the Cameroonian coast

This study provides a novel assessment of heavy metal contamination and related ecological risks along the lower part of the Cameroonian coast, a coastal area that has not been previously investigated in detail. To characterize the spatial distribution, evaluate the pollution intensity, and determine the potential ecological impact, sandy sediments were collected and analyzed geochemically using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The mean concentrations (mg/kg) of the analyzed elements followed the order Fe > Al > Mn > V > Ni > Co > Sc, all of which were lower than the Upper Continental Crust (UCC) reference values, indicating limited contamination. The geo-accumulation index (Igeo) and contamination factor (CF) values for all metals were below 0 and 1, respectively, suggesting that the sediments were unpolluted to very slightly contaminated. Similarly, pollution load index (PLI) values ranged between 0.29 and 0.35, confirming an overall clean sedimentary environment. The enrichment factors (EF < 1.5) also revealed a predominantly natural geochemical origin for the metals. The potential ecological risk indices (Er and RI) indicated a very low ecological risk across all sites. Statistical analyses, including Pearson correlation, cluster analysis, and principal component analysis (PCA), showed consistent metal associations linked mainly to natural weathering of source rocks with minor anthropogenic inputs. The main potential human influences include residual waste disposal, intensive agriculture, and industrial effluents that could locally alter sediment quality. This research contributes new baseline data for environmental monitoring and provides insight into natural versus anthropogenic metal inputs along the Cameroonian coast, supporting future coastal management and pollution prevention strategies.