The influence of technogenic and natural factors on the content of heavy metals in soils of the Middle CisUrals region: The town of Chusovoi and its suburbs

The content of heavy metals in the soils of the Middle CisUrals (the town of Chusovoi and its vicinities) is controlled by both natural and technogenic factors. The enrichment of the parent rocks in Cr, Pb, Zn, and Cu, which influences the chemical composition of the soils, is the most important among the natural factors. Among the other natural factors, the gleying and washing of the alluvial soils with flood water are significant. The technogenic contamination of the urban soils reaches its maximum in the technozems, where the content of Cu, Zn, Pb, and Cr exceeds their clarkes by 4–8 times. The index of technogeneity (the share of technogenic metals referring to their total content) is high for the bulk of metals in technozems, in particular, ranging within 36–97%. The technogeneity sequence is the following for the urban soils: Cr > Zn = Mn > Pb > Cu > Fe. The soil contamination with metals is confined to the depression where the metallurgical plant is operating, and it significantly falls already at a distance of 2–3 km in the settlements located at higher topographic positions.