The monograph summarizes the results of long-term studies of soil contamination of Karelia with heavy metals. Patterns of content and distribution of heavy metals by profile in soils of undisturbed forest ecosystems are shown. The results of the background monitoring of the soils of the state reserves "Kostumukshsky" and "Kivach", soil studies in various types of landscapes of the middle-taiga subzone of Karelia. These data can serve as a starting point for the indication of soil contamination by heavy metals. The results of environmental monitoring in the area of impact of the Kostomuksh mining and processing plant, which is one of the largest sources of atmospheric and soil pollution in Karelia, are summarized and presented . Due to the intensive development of forest resources, the information provided on the accumulation of heavy metals in the soils of natural and forested pine forests is relevant . Contamination features of g. Petrozavodsk heavy metals and made up the cartoscheme of their content in the upper horizons of urban soils . The threshold of sensitivity of microorganisms to heavy metals is established depending on their systematic position, as well as the biological activity of soils against the background of changes in soil factors. The presented material can be used for the development of environmental measures, solving problems of soil protection from pollution, for environmental monitoring. For biological professionals, teachers, graduate students and students.