Вестник МГТУ. 2020, Т. 23, № 1.

Conclusion As a result of this study of 15 small lakes in the southern part of the Republic of Karelia and core samples of the sediments from these lakes, the average content of 42 chemical elements, including heavy metals, was estimated, which can be used as background values for the study area. Our analysis of the obtained background values showed that the deeper (pre-industrial) sediment layers in the lakes are significantly depleted in all elements compared to the continental crust. An exception is Mo, whose ores and ore occurrences are widespread in the south of Karelia. In addition, it was found that the averaged concentrations of rare-earth elements in the sediments of lakes in the south of Karelia have a similar distribution pattern with the trend observed in the upper continental crust. Enrichment in light rare-earth elements and a negative Eu anomaly were observed. A comparative analysis of the obtained background levels of Pb, Cd, Cu, Ni, Zn, Cr and similar data from the Murmansk Region and Scandinavian countries highlighted the compared values that are similar. In addition, similar values were obtained when comparing the average concentrations of chemical elements in the lake and river and stream sediments in the south of Karelia. A minor difference was found only for Sr, V, and Cr that to a large extent gravitate toward the terrigenous fraction of the sediments, which is better represented in stream sediments. Our findings can form the basis for an extensive study of the background concentrations of chemical elements in sediments throughout the Republic of Karelia, including the identification of the background values of elements for different lithological types of sediment (sapropels, diatomites, mineral, ferruginous, and carbonate sediments). Acknowledgments The author expresses gratitude to A. S. Medvedev, D. G. Novitsky, E. V. 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