Seasonal accumulation of trace elements in native Mediterranean mussels ( Mytilus galloprovincialis Lamarck, 1819) collected in the Calich Lagoon (Sardinia, Italy)

The occurrence of 21 trace elements in native Mediterranean mussel ( Mytilus galloprovincialis ) from the Calich Lagoon, a typical brackish area of the northwest of Sardinia (Italy), was investigated. The seasonal variation of metals in bivalves was considered, and the highest values were found in spring and summer; in particular, a high significant ( P < 0.001) temporal variation was reported for silver (Ag) and mercury (Hg). The highest and similar concentrations were registered for aluminium (Al, mean 32 mg kg −1 wet weight), iron (Fe, mean 32 mg kg −1 w. w.), and zinc (Zn, mean 25 mg kg −1 w. w.). The maximum limits set by European Regulations for cadmium (Cd), mercury (Hg), and lead (Pb) were never exceeded. Speciation analysis revealed negligible risk related to inorganic arsenic (iAs). Therefore, M. galloprovincialis confirmed its role as suitable bioindicator to monitor the contamination of coastal environments. Although the recommended tolerable weekly intake (TWI) was not exceeded, the levels of aluminium should be carefully evaluated in monitoring plans in the studied lagoon. Graphical abstract