Rare earth elements and yttrium in shells of invasive mussel species from temperate rivers in Central Europe: Comparison between C. fluminea, D. bugensis, and D. polymorpha

Rare Earth Element and Yttrium (REY) have become emerging contaminants in the hydrosphere. REY contamination has been recorded worldwide and raises concerns about the REY's (eco)toxicity. Nevertheless, their environmental fate and the mechanisms of bioaccumulation remain unclear. We investigated the shells of three invasive mussel species from four temperate rivers (Rhine, Danube, Elbe and Weser) and three tributaries (Havel, Regen and Isar) in Central Europe. REY concentrations in shells are in the mu g/kg range and up to five orders of magnitude higher than those in ambient water. Interspecies comparison showed that Dreissena shells show systematically higher REY concentrations than Corbicula shells. Due to more stable complexation of heavy than light REY in river water or in the extrapallial fluid, light REY are preferentially incorporated into the shells. Anthropogenic La from fluid catalytic cracking catalysts is bioaccumulated in mussel shells from the lower reaches of the Rhine River. However, the anthropogenic Gd from MRI contrast agents released from wastewater treatment plants, that is observed in rivers worldwide, is not incorporated into mussel shells, revealing its conservative biogeochemical behavior.