Analysis of the accumulation and distribution of heavy metals in the soil cover of Samara and Syzran

The paper presents the results of a statistical analysis of the data on the accumulation and distribution of a number of heavy metals (Cr, Ni, Cu, Pb, Cd, Zn) in the soils of the cities of Samara and Syzran in the Samara Region, carried out using the Spearman’s rank correlation coefficient, the Kruskal-Wallis one-way analysis of variance and principal component analysis. The authors show that the soils of Samara are more susceptible to the accumulation of Cr, Ni, Cu and Cd than the soils of Syzran. Higher gross concentrations of metals are observed in the functional zones of the cities characterized by increased technogenic load – near industrial enterprises and along railways. The fixation of metals in the upper humus horizon is facilitated by the organic matter of the soil. The exception is Pb, whose total concentration does not depend on the type of functional zone and the content of organic carbon. The Kruskal-Wallis one-way analysis of variance made it possible to establish the presence of a statistically significant relationship between the mechanical composition of the soil and the gross concentrations of Cr and Ni, the content of which increases in soils of heavier texture. According to the principal component analysis, natural and technogenic sources of metals have a decisive influence on the content and distribution of heavy metals in the soil cover of the cities; soil characteristics (mechanical composition, actual acidity of the soil solution, organic carbon content) and the intensity of exposure to sources of heavy metals play a less significant role.