ALBERT

Description: The carbon isotope signatures and the content of polycyclic aromatic hydrocarbons (PAHs) in the pedogenic material of inclusions in ice wedges of the Batagay yedoma (Yakutia) are studied. The mean concentration of 11 PAHs is 170 ppb (minimum, 7 ppb and maximum, 430 ppb) and the mean δ13С value in soil lipids is -29‰ (minimum, -31.1‰ and maximum, -26.2‰). The prevalent polyarenes in associations are naphthalene homologs and phenanthrene. Trace amounts of heavy PAHs, including benzo[a]pyrene (an indicator of pyrogenic processes), are also detectable. The PAH contents and δ¹³С values in ice wedges show the trend of a decrease with depth. The δ¹³С values and PAH content suggest a pedogenic origin of the deposit: therefore, PAHs originate from plant residues and wildfires. The observed trend of changes in the concentrations of polyarenes along the ice wedge may be associated with the changes in landscapes in the Late Pleistocene.

Description: Molecular genetic techniques (FISH, RT-PCR, and metagenomic analysis) were used to investigate the comparative functional biodiversity in the prokaryotic complex in grassland and forests’ sod-podzol under polycyclic aromatic hydrocarbon influence. The polluted samples showed a decrease in the biomass of the prokaryotic community representatives and a change in the metabolically active dominants–representatives of the Bacteria and Archaea domains compared to the control samples. The suppression of the metabolic activity of prokaryote cells under the influence of PAHs in sod-podzolic soil under meadow vegetation was more pronounced compared to soils under forest vegetation. The representatives of prokaryotes that are sensitive and resistant to the studied PAHs were identified. The representatives of the phylogenetic groups from the bacterial complex resistant to PAH pollution were Proteobacteria (Alphaproteobacteria), Bacteroidetes, Firmicutes, Chloroflexi, and Thaumarhaeota in the archaeal complex. Representatives of the phylum Acidobacteria and Actinobacteria (Streptosporangiales) are noted among those sensitive to PAH contamination. The presence and expression of the functional alkane monooxygenase (alkB) gene were established in all the experimental variants studied. In the plant variants, the number of copies of alkB genes increased by an order of magnitude and the biomass of metabolically active prokaryotic representatives with the functional alkB gene doubled compared to the unpolluted territories. The copy number index of the alkB gene can be used as one of the parameters when characterizing an ecosystem for the presence of PAH pollutants.