Heavy Metals in Urban Soils of the Volga Federal District: a Conjugate Analysis of Official Data

Based on a conjugated analysis of the official data of Roshydromet on the content of priority heavy metals (Cd, Pb, Zn, Cu, Ni) in the soils of 23 cities of the Volga Federal District, as well as Rosstat data on the socio-economic indicators of these settlements, the ecological and geochemical characteristics of urbanozems (Urbic Technosols) and with the help of multivariate statistical analyzes (cluster and factorial), possible relationships between soil pollution parameters and urban features of cities were revealed. For the soils of most cities in the region with average socioeconomic indicators, admissible levels of accumulation of Cd, Pb, Zn, and Cu have been established, which, in terms of concentrations, are close to the average abundance of urban soils in Russia. In small and medium-sized cities of the Republic of Bashkortostan, exceedances of APC Ni in soils are recorded, which reflects the presence of a regional geochemical anomaly of natural and anthropogenic nature in the eastern part of the Volga Federal District, but no correlations between nickel pollution and socio-economic indicators of settlements are revealed. The moderately hazardous level of complex pollution in urbanozems with dominant accumulation of Cd and significantly lower concentration ratios of other heavy metals (Belebey, Davlekanovo, Dzerzhinsk) shows no correlation with the demographic indicators of settlements. The more complex profile of soil pollution (Cd–Zn in Penza or Cu–Cd–Zn in Mednogorsk) shows lower values of the total fertility rate and higher values of the mortality rate (compared with the average regional indicators). In general, using the example of the cities of the Volga Federal District, it is shown that the gradients of increasing concentrations in soils of Cd, Pb, Zn, Cu and the total pollution index Zc are codirectional with an increase in the general mortality rate of the population.