The number of soil bacteria is an indicator of the conditions and health of soils under chemical pollution. However, the native abundance of soil bacteria in the soils of different climatic zones varies significantly, depending, among other factors, also on the soil-forming factors. To assess changes in the number of soil bacteria, we simulated lead (Pb) pollution of soils from different climatic zones (semi-desert, steppe, and forest). The experimental concentrations of Pb were 100, 1000, and 10 000 mg kg–1 of soil. Maximum concentration of Pb (10 000 mg kg–1 of soil) decreases the soil bacteria abundance in different types of soils by 46–92% compared with the control. An increase in Pb concentration leads to decrease in the number of soil bacteria from 1.61 billion g–1 (typical solonchak) to 0.89 billion g (chestnut and brown semi-desert soils), from 4.50 billion g–1 (podzolic chernozem) to 0.80 billion g–1 (common chernozem), and from 8.00 billion g–1 (dark gray forest soil) to 1.90 billion g–1 (sod-podzolic soil) in semi-desert, steppe, and forest soils, respectively. The soils of the forest climate zone are the most resistant to Pb pollution, while the soils of the steppe climate zone are the least resistant. The most vulnerable to the soil pollution are the bacterial communities from the typical solonchak, podzolic chernozems, and sod-podzolic illuvial-ferruginous soils in the semi-desert, steppe, and forest zones, respectively. The number of soil bacteria in three climatic zones of Russia polluted with lead contamination has been compared. The results of the study can be used in assessment of the ecological status and health of soils contaminated with heavy metals.
Kutasova et al. (Sun,) studied this question.