Similarities and differences of potentially toxic elements contents in leaves of Fraxinus excelsior L. and Platanus orientalis L. in an urban environment

The recognition of the features and capabilities of potentially toxic elements (PTE) uptake from urban tree leaves is crucial for mitigating pollution and optimizing the allocation of green infrastructures of an urban environment. Therefore, Pb, Ni, Mo, Cu, Zn contents and spatiotemporal variation were investigated in the leaves of the most widespread urban trees in Yerevan (Armenia) (Fraxinus excelsior L. and Platanus orientalis L.) by means of a chemical approach based on atomic-absorption spectroscopy, after having washed them. The obtained results showed similarities in leaves Ni, Cu, Pb and Mo uptake. Meanwhile, only biologically non-essential elements (Mo and Pb) tend to accumulate in leaves during the vegetation season. This allows for the identification of localized pollution sources. Spatiotemporal variation of Zn contents suggested that P. orientalis L. is the less efficient tree species in Zn uptake. The study of the relationship of Pb, Ni, Mo, Cu, and land use by means of clr-biplots showed the absence of any potential links. Moreover, it was revealed that the element contents of leaves in green areas are similar to those observed in industrial and residential sites. The latter highlighted the need for the expansion of green areas with the use of scientifically justified species as a means of nature-based solution for pollution mitigation and better urban environmental management.