Assessment of the level of pollution based on soil and Tilia × europaea leaves

Abstract Anthropic activities related to urbanization release pollutants, including potentially toxic elements which can deposit in soils, water, and vegetation. Thus, soil and plant leaves are widely used as ecological indicators to assess the effect of urbanization. This study aimed to evaluate the impact of urbanization based on the elemental concentration of soil and leaves of Tilia × europaea from urban, suburban, and rural areas along an urbanization gradient in Debrecen, Hungary. The rural area was situated near Nagyerdő, a protected area for nature conservation The suburban area was intermediate between the rural and urban areas regarding urban density. The urban study area was at the centre of the urban community to maximize the observable effect of urban pollution. Using inductively coupled plasma optical emission spectrometry (ICP-OES) technique, the concentration of Ba, Cd, Co, Cr, Cu, Ni, Pb, Sr, and Zn was analysed and based on them, bioaccumulation factor (BAF) was calculated. The highest concentration of all elements was found in soil samples from urban areas, with an increasing tendency along the urbanization gradient. A significant difference was found along the urbanization gradient only for Cr based on the plant leaves. T. × europaea showed bioaccumulation capacity for Cr and Sr. Our results suggest that urbanization has a remarkable effect on the elemental concentration of soil, which is a perfect ecological indicator. At the same time, we concluded that the T. × europaea was not sufficiently sensitive to detect the effect of urbanization.