Biological Activity of Microbial Communities in Soils of Some Russian Cities

Comprehensive studies of soils in some Russian cities (Nadym, Yaroslavl, Moscow, Chelyabinsk, Kursk, and Sochi) were carried out. In relation to natural analogues, the direction and degree of changes in the properties of the upper soil horizons and the state of soil microorganisms are controlled by the natural zone, where the city is located, and by the kind and level of anthropogenic load. Most often, the Corg content, pH, and the electric conductivity in urban soils of northern regions reliably increase in comparison with those in their natural analogues, while urban soils in southern regions manifest diverse trends. In the soils of all cities, the number of cultivated prokaryotes increases reliably (by 1.5–5.2 times), as well as the percentage of microorganisms–indicators of urbanization, such as actinomycetes (by 33–71%) and Rhodococci (by 18–27%) secreted on selective media. According to the degree of soil transformation, urban landscapes may be ranked as follows: park-recreational, residential, residential-transport. The intensity of the functional activity of microorganisms points to the disturbed biogeochemical cycles of elements in urban soils. The emission of carbon dioxide and methane, as well as nitrogen fixation, displays an intricate dependence on the position of the city in the natural zone and on the level of anthropogenic load.