The Impact of the Degree of Urbanization on Spatial Distribution, Sources and Levels of Heavy Metals Pollution in Urban Soils—A Case Study of the City of Belgrade (Serbia)

Abstract

This study investigated the effects of urbanization on the spatial distribution, sources, and levels of heavy metals pollution in urban soils of the city of Belgrade. A total of 126 composite topsoil (0–10 cm) and subsoil (10–40 cm) samples was collected within four urban zones (central, suburban, external, and rural) of Belgrade and analysed for content, spatial distribution, sources, and pollution indices using statistical methods including descriptive statistics, correlation matrix, and Principal Component Analysis (PCA). Concentration levels of zinc (Zn), copper (Cu), cadmium (Cd), chromium (Cr), and nickel (Ni) in the soil of urban zones in Belgrade were found to be significantly higher in the central and suburban zones compared to the external and rural ones. The spatial variance and the general trend of heavy metals accumulation in the soil were found to be along the urban–rural gradient. The topsoil concentration levels for the same elements were higher compared to the subsoil concentration levels for the same elements in all urban zones, except for the external and the rural zones. These results indicate the need for the implementation of urban soils pollution monitoring according to specific urban zones to provide an applicable basis for the development of plans and strategies concerning urban soil use management for the purpose of the sustainable urban development.