This study is a bio-indicative evaluation of anthropogenically-polluted soils of the city Mednogorsk in orenburg region, Russia. This work evaluated – the total number of heterotrophic microorganisms, the number of iron- and manganese-oxidizing bacteria in the polluted soil samples, the activity of soil enzymes (dehydrogenase, catalase, invertase), and also the magnetic susceptibility of these soils (Kmag) – an index which shows the concentration of iron (Fe) in soil. 10 samples were analysed which showed the highest coefficient of magnetism (Kmag > 3) and also a reduced content in heterotrophic microorganisms compared to the control soil samples with Kmag <1, which indicates the inhibitory effect of heavy metals on soil bacteria. It was discovered that soil samples with extremely high significance of magnetic susceptibility possessed high amount of iron-oxidizing bacteria in their soil microbial community. Also, based on the sensitivity to metallic pollution, the studied enzymes formed a decreasing order: dehydrogenase>invertase>catalase. This study reveals the possible use of these indicators as diagnostic tools for monitoring soils polluted with heavy metals.
Key words: Heavy metals, Coefficient of magnetism, iron- and manganese oxidizing bacteria, Heterotrophic microorganisms, Dehydrogenase, Catalase, Invertase.
Introduction
As a result of anthropogenic pollution, significant amount of different xenobiotics are released into the environment among which the most dangerous are heavy metals (HM) [1]. Heavy metals accumulating in soils reduce its biological potential: changes the number, species composition, biomass and productivity