Assessment of trace metal contamination in surficial fine-grained sediments and mussel, Mytilus galloprovincialis from Safi areas in the northwestern Atlantic coast of Morocco

Abstract During the spring season, trace metal concentrations of cadmium (Cd) and copper (Cu) were investigated in surficial fine-grained sediments and the blue mussel Mytilus galloprovincialis. The study was conducted on the Atlantic coast of Morocco at two selected points along Safi shores, a supposed clean station and a recognized metal-contaminated one. The main objectives were to assess the pollution status of these two stations and to highlight the environmental and human risks associated with metal contamination. The bioavailability and the bioaccumulation of the selected metals, several physiological and biometric parameters of mussels were assessed at both sampling stations. As expected, the station located near industry plants showed the highest metal concentrations in the two compartments and was associated with lower values in the physiological and biometric indices. At the mussel scale, inter-station and inter-tissue variations in metal concentrations were observed showing a preferential accumulation within the digestive gland. Besides, strong reliable negative relations of Cd and Cu concentrations were obtained with physiological indices. Surprisingly, a significant occurrence of both selected metals was recorded at the location assumed as a reference station. Therefore, the hypothesis that this station presumed to be clean and currently used as a control station must be reconsidered. As for the risk for the consumer, the estimated daily intake (EDI) of Cd and Cu indicated a potential health risk through mussel consumption since the EDI values were markedly above the international guidelines and threshold levels for human consumption. Finally, our data were compared to those previously obtained along the Safi coastline (NW Morocco) and other geographical regions, including the Mediterranean and western Atlantic areas within the temperate zone.