Trace metals in urbanized coasts: The central Atlantic of Morocco as a case study

This study describes the contamination, accumulation, and ecological risk assessment of five trace metals (Cd, Pb, Cu, Zn, and Cr) in sediments of an urbanized beach in the central Atlantic coastline of Morocco. The two-year investigation (2018 and 2019) included six sampling sites along a 6 km coastal reach. In both years, none of the studied trace metals exceeded the background or the sediment quality guidelines (SQGs). The eco-toxicological indices revealed low degree of contamination, unpolluted ecosystem, and low ecological risk of metals. However, Cd exceeded the background value and some SQGs following the increase of anthropogenic activities in 2019. Likewise, it indicated unpolluted to moderately polluted sediment as well as moderate ecological risk. Overall, it is highly recommended to mitigate the avoidable anthropogenic activities (marine litter generation, sewage discharge, intense urbanization, and vehicle traffic on the beach) that lead to the elevation of metal pollution in the study area.

The chemical characterization and its relationship with heavy metals contamination in surface sediment of Marchica Mediterranean Lagoon (North of Morocco)

The sediments were studied according to the granulometric characteristics, the geochemical analyses of the sediments (organic matter (OM), carbonate, and pH), the analyses of heavy metals (HM) characteristics, and their contamination status in the ecological system and the mineralogical analysis of the sediments at 8 sites spread over the Marchica lagoon (NE-Morocco). Our results showed that the opening of the new wide and deep pass affected the spatial distributions of the metals, which were closely related to fine fraction and sediment OM concentration. In the north and southeast lagoon zones presented low concentrations of the HM, fine particles (clay), OM, whereas the south and the center of the lagoon were heavily loaded with HM and OM, corresponding to the trapping zones by fine particles. The results of mineralogy analyses have revealed the predominance of non-clay minerals such as quartz and calcite, and for the clay fractions of sediments showed that they are formed of illite, kaolinite, smectite, and chlorite in highly variable proportions; illite was the most dominant clay in the north-western Marchica lagoon sediments. Therefore, the HMs are fixed by clay colloids having a high cation exchange capacity with smectite-chlorite-kaolinite assembly.