Rare earth elements in transitional ecosystems: preliminary data from the LTER Lagoon of Venice site (Italy)

Rare Earth Elements (REEs) are essential for advanced technologies and high-tech applications, yet their presence and impact in marine and transitional ecosystems remain poorly understood. This study provides a preliminary assessment of their distribution in the Venice Lagoon (LoV), a large Mediterranean coastal lagoon in northeastern Italy, by analyzing three environmental matrices: water, sediments, and mesozooplankton. Particular attention was given to Acartia (Acartiura) clausii and Acartia (Acanthacartia) tonsa, two dominant copepod species. Seasonal samples were collected from three sites characterized by different environmental conditions and varying degrees of anthropogenic influence. REE concentrations were determined using ICP-MS after acid digestion. Results indicate that REE concentrations in water were below the quantification limit, while sediments exhibited an enrichment of light REEs (LREEs) over heavy REEs (HREEs). In mesozooplankton, bioaccumulation was limited but detectable, with a spatial gradient showing higher concentrations in areas under strong anthropogenic pressure (San Giuliano) and lower values in marine-influenced sites. Seasonal patterns suggest that temperature and primary productivity influence REE uptake. These findings provide a baseline for monitoring REEs in the Venice Lagoon and underscore the need for further research on their environmental fate and potential ecotoxicological impact, particularly on zooplankton communities.