Interactive effects of palladium (Pd) and microplastics (MPs) on metal bioaccumulation and biological responses in the Mediterranean mussel, Mytilus galloprovincialis

This study investigates the potential of MPs as carriers of pollutants as they can strengthen bioaccumulation of toxic metals on marine organisms. For the first time, the interaction of the metal palladium (Pd) with the widespread MPs, both with increasing concentrations in water environments from anthropogenic sources, was tested. Mytilus galloprovincialis, an important seafood product, was exposed to Pd (24 h) in two ways: water-dissolved and MPs-adsorbed, with depuration followed for 144 h. Quantification of Pd in tissues shown an accumulation 2–3 times higher (59 % of initial Pd) for mussels exposed to MPs-adsorbed Pd and higher in digestive gland than when exposed to water-dissolved Pd (25 %; higher in gills). Additionally, it was demonstrated that Pd induced oxidative stress and altered the feeding behavior of mussels. Therefore, this work support MPs as being vectors of metals (i.e. Pd) to enhance their bioaccumulation on marine organisms which highlights ecological risk of these emerging pollutants. •Pd assimilation increases when bonded to MPs.•Bioaccumulation of Pd is higher in the presence of MPs.•MPs elimination from mussels is not followed by Pd depuration.•Accumulation route of Pd in mussels is altered when ingested adsorbed onto MPs.•Dissolved Pd induces oxidative stress and alters the feeding behavior of mussels.