Urban soil geochemistry of an intensively developing Siberian city: A case study of Tyumen, Russia.

Complex studies of soil cover within the urbanized areas represent one of the main research directions in environmental geochemistry. Urban soil geochemistry depends on a combination of natural and urbanization factors unique to each urban environment. Although Tyumen, in Western Siberia, is an intensively developing urban city, a detailed geochemical survey of its soils has never been performed. In this study, we conducted a systematic geochemical soil survey across the urbanized area of Tyumen, Russian Federation. Surface soil samples (0-10 cm) were collected from 241 sampling sites: 1 × 1 km regular grid for highly urbanized areas, and 4 × 4 km grid for peripheral parts of the city. The contents of V, Cr, Co, Ni, Cu, Zn, As, Sr, and Pb were determined using XRF analysis. Data were interpreted using GIS and multivariate statistical analyses, including hierarchical cluster analysis and principal components analysis. The results showed a non-uniform spatial distribution of individual metals, associated with natural soil-lithological conditions and urban environment characteristics. Our data showed that variation in soil element content was origin dependent: V, Cr, and Co contents were related to their natural origin; As and Pb to their anthropogenic origin; and Ni, Cu, and Zn to their mixed origin. Elevated V, Cr, Co, Ni, Cu, and Zn contents correlated with proximity to motorway networks and machinery. Strong As and Pb anomalies were associated with the activity of battery enterprises. The spatial distribution of Sr was significantly different from other studied elements - anomalous content of this metal was confined to hydromorphic boggy landscapes of the city's northern part. In general, Tyumen territory was slightly polluted with metals. Zn and Pb contents were slightly lower than in most cities with similar population levels, while those of V and Co were higher. Other metal contents were comparable to those in large cities, with a long history of industrial development. Elevated Cr, Ni, Zn, Cu, As, Pb, and Co contents were observed in areas that developed during mid last century.