Quantitative evaluation of several geochemical characteristics of urban soils

Abstract

For the first time, the quantitative geochemical data are given for urban soils of several groups of cities which differ in population. The content of chemical elements is considered as well as the specific ecological significance of soil contamination by these elements. The figures were established by authors on the base of average concentrations of chemical elements in the soils of more than 300 cities and settlements. The major part of data (sampling, analyses, and their statistical treatment) was obtained directly by authors as a result of special studies conducted for more than 15 years. The sufficiently numerous published materials of different researchers were also used. The greatest elements accumulation comparing with the Earth’s soils (tens of thousands of tons per 1 km2) is associated with an increase in the content of Ca and Mg. Considering the environmental significance of chemical elements accumulation in soils, we note the primary role of Pb and Zn in all groups of cities. Out from the rest pollutants it is necessary, first of all, to note As, Cu, and Cl, which are the main contaminants in four of six cities groups. In two groups of settlements, Cd and Co are important soil pollutants. In three groups, a considerable increase in the Ca content significantly modifies ecological–geochemical state of soils.