the objective of this study was to evaluate the quality of surface sediments and the ecotoxicological risk associated with heavy metals (lead, nickel, copper, and cadmium) in La Esmeralda Bay, Sucre State, Venezuela, and to analyze their interaction with particle size distribution, organic matter (OM), and carbonates. To this end, samples were taken at twenty stations during 2017, metals were quantified using atomic absorption spectrophotometry, and particle size distribution and OM were determined. The toxicological assessment was performed by comparing the Limit Effect Concentration (LEC) and Probable Effect Concentration (PEC) thresholds and calculating risk indices such as the Contamination Factor (CF) and the Potential Ecological Risk Index (PERI). The results revealed a heterogeneous and seasonal particle size distribution; OM was higher during the rainy season and associated with fine grains. Ni exceeded the CEL at multiple stations and the CEP at station 1, while cadmium consistently exceeded the CEL at all stations in both sampling periods. The Pollutant Load Index (PLI) indicated significant environmental degradation. The IREP showed an alarming potential widespread ecological risk during the rainy season. Metal accumulation is favored by fine particle size and organic matter; however, the positive classification with sands suggests that the main source of these metals is continental. In conclusion, cadmium represents a growing threat with a very high risk, while the localized concentration of Ni suggests a specific emission source that requires immediate identification and mitigation to reverse the sustained deterioration of the ecosystem.
