Accumulation of Heavy Metals in Soils and Phytomass in Urbanized Areas

Abstract

Purpose: To carry out a qualitative and quantitative assessment of the content of heavy metals (Fe, Zn, Pb, Cd) in soils and aboveground vegetation organs of plants of the Olive family, namely the common lilac (Syringa vulgaris) growing in urban areas, using the example of the central part of the city of St. Petersburg. To assess the accumulation of iron, zinc, cadmium and lead by soil cover and phytomass, depending on the remoteness of the street-traffic network adjacent to garden-park areas, and the traffic intensity along the studied highways. Methods: The experimental method, based on the “Methodology for determining vehicle emissions for conducting summary calculations of urban air pollution”, has been used to determine the composition and traffic intensity of the traffic flow passing along highways adjacent to the study areas. Subsequently, the obtained data have been statistically processed. A total of 20 sampling points have been identified at the study sites, at different distances from the pollution source. Based on the adopted “Methodological guidelines for determining heavy metals in soils of agricultural lands and crop products”, samples have been taken and further sample preparation has been carried out for research by flame atomic absorption spectrometry. In the laboratory of the testing center “Ecological and Occupational Safety” of the Federal State Budgetary Educational Institution of Higher Education PGUPS, using the method of flame atomic absorption spectrometry, a quantitative analysis of the content of heavy metals (Fe, Zn, Pb, Cd) in selected soil and phytomass samples has been carried out. Results: The quantitative and qualitative composition of the intensity of the traffic flow passing through the central part of the city of St. Petersburg has been determined. The concentrations of heavy metals (Fe, Zn, Cd, Pb) have been determined in all selected soil samples and phytomass at the beginning and at the end of the growing season, leaves of common lilac shrubs growing in the central regions of the city of St. Petersburg. In most samples, elevated concentrations of heavy metals have been found in the aboveground vegetation organs of shrubs taken at the end of the growing season, compared with those taken at the beginning of the growing season. Practical significance: It is shown that the accumulation of heavy metals in plants and soil largely depends on the location of the pollution source and its intensity. The data obtained can be recommended for practical use.