Heavy metal bioaccumulation in sediments and mussels along the moroccan mediterranean coast: A spatial assessment

Abstract

Due to its strategic location and rapid development, the Moroccan Mediterranean coast is particularly vulnerable to trace metal contamination. This study examines the spatial distribution of selected heavy metals in surface marine sediments and in the tissues of the mussel Mytilus galloprovincialis, a species widely consumed by humans and other animals, from six strategically chosen coastal stations. Sediment and mussel samples were collected and analyzed using atomic absorption spectrometry (Varian AA 20 AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES 720-ES), respectively. In sediments, the metal concentrations decreased in the following order: Zn > Cu > Cr > Pb > Fe > Cd, with chromium reaching a maximum concentration of 45 mg/kg at the most contaminated site. In mussel tissues, the sequence was Fe > Zn > Cu > Cr > Cd > Pb, with iron concentrations peaking at 524 mg/kg. Pearson correlation analysis revealed moderate relationships between metal concentrations in sediments and mussels for most elements, except for Fe and Zn, while multiple regression analysis indicated that cadmium levels in sediments significantly influenced Cd bioaccumulation in mussels. Although our enrichment factor analysis suggests relative anthropogenic input, the overall metal loads remain low—a result likely attributable to the sandy nature of the sediments and active hydrodynamics that limit material retention. Collectively, these findings provide critical baseline data on metal bioavailability in this dynamic coastal system and have important implications for ecological risk assessment and food safety management in the region.