Sources of Soil and Plant Contamination in an Urban Environment and Possible Assessment Methods

Abstract

A survey was carried out in the city of Brno, Czech Republic in order to determine the levels and sources of soil and plant contamination and the possible implications for human health. A group of 136 topsoil and plant samples were taken in a defined sampling pattern, both in urban (in the year 1991) and suburban (1992) areas, paying particular attention to traffic density and intensity of land use. Samples were analysed for the contents of six heavy metals (Cd, Cu, Cr, Ni, Pb, Zn) and polycyclic aromatic hydrocarbons. The main soil characteristics were also determined (p^H, CEC, C_ox).

Traffic influence indices (TII) were calculated for each locality based on the traffic density and micro climatic conditions. Soil pollution indices (SPI) and plant pollution indices (PPI) were defined as a loading of a group of toxic metals relative to acceptable upper limits and were used as a general measure of the soil and plant burden at a particular site.

There were significant differences between the level of pollution in urban and suburban areas particularly for Pb, Cr and Ni in plants.

Traffic was found to be the major source of pollution by Pb, Zn and Cu in the urban survey and significant correlations were found between soil Pb × TII and SPI × TII in urban area. No such relationships were found for the suburban samples.

Key Words:

• Heavy metals
• PAHs
• soil contamination
• plant contamination
• urban environment
• assessment methods