Rare earth elements biomonitoring using the mussel Mytilus galloprovincialis in the Portuguese coast: Seasonal variations

Increased Rare earth elements (REE) usage culminates in discharges into the environment. Mussels have been chosen as models in biomonitoring, hence, REE concentrations in Mytilus galloprovincialis from six locations on the Portuguese coast were accessed to determine natural concentrations and possible linkage to local ecosystem characteristics and temporal variations, by determining them in distinct seasons (autumn and spring). Samples from Porto Brandão (located on the south bank of the Tagus estuary) exhibited the highest REE concentrations, while mussels from Aljezur (the southernmost point on the Portuguese coast) exhibited the lowest, in both seasons. Overall, ∑REE concentration was greater in the spring. LREE enrichment relative to HREE occurs and a negative Ce and Eu anomaly was observed. This study constitutes the first assessment of REE composition on this model species in the Portuguese coast, in two distinct seasons and contributes to a better understanding of REE uptake for future biomonitoring studies.