Evaluating the Capability of Woody Plants to Capture Atmospheric Heavy Metals in Budapest

Abstract

Urban green infrastructure planning plays an important role in aspects of pollution reduction, such as heavy metal trapping. However, the reduction effects are both influenced by the different pollution conditions in each city and the species-specific interaction of trees and pollution. Herein, we investigated three common urban woody plants (Acer platanoides L., Fraxinus excelsior L. Westhof’s Glorie, and Tilia tomentosa Moench) in Budapest to compare their heavy metal trapping abilities from the airborne in leaf dust deposits and leaves. All samples were deconstructed by a wet digestion method. Four high traffic-related heavy metal elements (Zn, Cu, Pb, and Ni) were determined by using an atomic absorption spectrometer (AAS). The investigated results showed that the relevant concentration of all measured elements was constant in all species, namely Zn < Cu < Pb < Ni. Although the total heavy metal content in the dust deposit increased towards the end of one vegetation period, the highest percentage of total metal concentration was in the summer season as the particulate matter sources varied in each season. These indicate that woody plants are ideal candidates for pollution monitoring. All of the evaluated elements were loaded highest in the dust deposit of T. tomentosa during all sampling times, followed by A. platanoides, and the least in F. excelsior. A significant correlation between metal contents in the dust deposit and leaf was found in T. tomentosa (0.926 at a p<0.01 level). Therefore, we suggest T. tomentosa, which has better atmospheric trace element capturing capacity than A. platanoides and F. excelsior and thus it is a better option for pollution reduction in the urban area.