Dynamic of Soil Contamination in the Cities with Different Technogenic Impact
Objective: The research was focus on monitoring heavy metals content in urban soils with different levels of technogenic impact, taking into account heterogeneity of soil cover and the functional purpose of land. Methods: Studies were carried out simultaneously in the two cities of Ukrainian (Berdyansk and Mariupol) on the Azov Sea coast, which significantly differ by the structure of industrial production. The area of each monitoring cities was at least 2500 m2, where were choosing 30 sites of baseline survey. On the each site the number of individual soil samples included in the mixed sample was 18-20. The time series of observations: 2002-2003, 2007-2008, 2012-2013. The available forms of heavy metals in the soils were determined by atomic-absorption method after extraction of buffer solution with pH 4.8 as well as 1 N HCl.
Result: Dynamics of soil contamination in the studied cities was significant different due to the reorientation of the industrial structure during the research period. In Berdyansk the level of soil contamination in the industrial zones gradually decreased, but heavy metals (Zn, Cu, Mn) began accumulate in soils of residential, cultural and administrative areas, in recreation objects. In contrast to this, due to the intensive activity of the enterprises of iron and steel industry in Mariupol the level of soil contamination in industrial, residential areas has increased by 8-18% and was higher than in Berdyansk in 1, 5-2 times. This is caused by the accumulation of Zn, Mn, Pb and mineral salts, sometimes in excess of the permitted rate.
Conclusion: Due to extremely high heterogeneity and combination of pollution from multiple sources, the changes of urban soil quality can be objectively assessed only by the systematic monitoring. The quality of urban soils is improving over five-ten years after reducing the amount of industrial pollution. Soil quality is deteriorating significantly in case of a constant dominance of steel industry over other activities.