Assessment of heavy metal contamination in the surficial sediments from the Sebou River Estuary, Morocco

The present study analyzed the concentrations of four heavy metals iron (Fe), manganese (Mn), zinc (Zn), and lead (Pb) on the surface sediments in Sebou river estuary (Morocco) and evaluated the role of sediment grain size and organic carbon (OC) on the distribution of metals. Sixteen numbers of surface sediment samples collected during the summer period of 2019 from Sebou estuary were used for the study. The dominance of fine-grained sediments (clay and silt) was observed in the study region. The organic carbon distribution indicates that they were brought from the surroundings of coastal areas. Correlation analysis indicates that fine-grained particles and organic carbon (OC) control the distribution of metals and suggest strong association between metals and fine-grained fractions. Significant correlations were evident between Zn and Mn (r = 0.66), and between Mn and Fe (r = 0.70). The correlations between OC versus Mn (r = 0.80), OC and sand (r = -0.70), OC versus silt (r = 0.96), and OC and clay (r = 0.87) were significant. Contamination levels of metals were examined by using geo-accumulation index and contamination factor, which indicate that the estuarine sediments were unpolluted to moderately polluted with heavy metals. The study thus provides baseline data on the heavy metal distribution in the Sebou estuary for identifying the source of future contamination.