Background concentrations of trace elements in recent lake sediments of the Murmansk region: new data

New data on the background contents of 43 chemical elements in recent sediments of lakes in the Murmansk region are presented. To create the basis for calculations, the authors' materials obtained during field work in 2018-2024, as well as archival data, were used, which made it possible to create a database of 417 images from 53 lakes in the Arctic region. The data for calculating the background were selected based on the paleolimnological principle, which allows cutting off the upper layers of sediments that are contaminated as a result of anthropogenic activity with heavy metals (e.g. Pb, Sb, Cd, V and Ni). The main statistical parameter, which became the final background value for each element, was the median, which is more resistant to extreme concentrations in data samples. Studies have shown that, in general, the background level of rare elements in the sediments of lakes in the Murmansk region is below the clarke. Exceptions are the median values of Zn, Mo, Cd and U. This is partly due to the extremely low clarke content, for example, Cd, compared to sedimentary formations, which is also confirmed by studies of lake bottom sediments in other regions of the world. At the same time, higher clarke values for Mo and U may be evidence of the presence of a significant influence of ore-bearing rocks of the Murmansk region on the geochemical features of the sediments of lakes located near them. In particular, this is confirmed by a detailed study of the accumulation of U in the sediments of reservoirs of the Litsevsky uranium ore geological region.