<p>This study investigates the biogeochemical and environmental characteristics of humic acids isolated from sediment samples of five lakes located in the European taiga zone. Sediment samples were analyzed using advanced techniques, including CHN analysis, solid-state 13C-NMR spectroscopy, and FTIR spectroscopy. The results show that the humic acids from the studied lake sediments exhibit lower degrees of aromaticity compared to those in terrestrial soils, indicating a lower degree of humification under aquatic reducing conditions. This suggests that aquatic environments favor the preservation of relatively labile organic compounds. The affinity of metals to form complexes with the humic acids varied among the lakes, with metals such as Co, Pb, V, and Sb forming stable chelate complexes, while Mn and Cd exhibited higher geochemical mobility. The findings provide insight into the role of humic substances in controlling the distribution and mobility of metals in aquatic ecosystems, contributing to our understanding of biogeochemical processes in taiga lake environments.</p>