Assessment of environmental pollution with rare-earth metals through bioaccumulation studies using vegetal bioindicators

Environmental pollution by anthropogenic activities has become a global concern as the release of organic and inorganic pollutants into the atmosphere is responsible for important health problems among the population. The rare-earth metals processing sector has raised particular problems due to the bioaccumulation potential of these metals in the food chain. Urban trees are able to retain pollutants from the environment and can be used as bioindicators also for the rare-earth metal pollution. This paper aimed to assess the bioaccumulation of some rare-earth metals, besides other metals and non-metals, in the foliar part of six urban tree species (Populus nigra L., Populus tremula L., Populus x canadensis Moench, Betula pendula Roth, Aesculus hippocastanum L. and Fraxinus excelsior L.) sampled from different areas of the municipality of Bucharest. Laboratory experiments have shown that all tree species used in the study are able to retain rare-earth metals, but the bioaccumulation capacity is species-specific.