Selection of forest species for use in urban environment in relation to their potential capture to heavy metals

The aim of this research is to study the behavior of different forest species in accordance with their ability to retain heavy metals on their leaves in order to select the most suitable species for urban and peri-urban use, which will contribute to the reduction of the continuously growing atmospheric pollution in the cities. Five species were studied: Cupressus arizonica, Albizia julibrissin, Platanus orientalis, Celtis australis and Ligustrum japonicum. 360 leaf samples were collected and two treatments (non-washed and washed sheets) were applied on them. The determinative estimation of the concentration of metals in the clear filtrate was carried out with the use of ICP-OES inductively coupled plasma optical emission spectrometry. In order to correlate the concentration of heavy metals in leaves with the silvicultural characteristics of species, the following characteristics were measured in 20 individuals per species: diameter at breast height, total height of tree, crown beginning height and crown’s diameters. Statistically significant differences between the studied species were found for all metals. In addition, not a single species was found to retain the highest concentration of all. Metal concentration on leaves’ surface in declining order was: (Mn) > (Cu) > (Zn) > (Pb) > (Cr) > (Ni) > (Cd). The factor of height is significant both in the upper and lower layer of the crown. Broadleaves’ species as Albizia julibrissin with compound leaves capture significant heavy metals as conifer species.