E. D. Lodygin

Molecular composition of humic substances in tundra soils (13C-NMR spectroscopic study)

Functional groups and molecular fragments of humic substances (HSs) from cryohydromorphic peat gley tundra and surface-gley tundra soils have been identified by 13C-NMR spectroscopy. The analysis of HS preparations has shown that the molecules of humic acids (HAs) are enriched with aromatic fragments compared to fulvic acids (FAs). Aliphatic chains, carbohydrate- and amino acid-type structures prevail in the carbon skeleton of the FAs. An integrated parameter of the HS hydrophobicity has been proposed. The parameter represents the total portion of unoxidized carbon atoms and allows indirectly assessing the amphiphilic properties of HSs.

Assessment of background concentrations of heavy metals in soils of the northeastern part of European Russia

The assessment of background concentrations of heavy metals in soils of the southern regions of the Komi Republic has been performed. Within the accumulative landscapes, soils are enriched with virtually all the studied heavy metals in comparison with the eluvial landscapes. A database of the content of heavy metals has been developed using GIS technologies, and maps showing the distribution of heavy metals in soils of the southern part of the Komi Republic have been obtained.

Polycyclic aromatic hydrocarbons in soils of Vasilievsky Island (St. Petersburg)

The composition and accumulation patterns of priority polycyclic aromatic hydrocarbons (PAHs) in soils of Vasilievsky Island in Saint Petersburg were studied. Concentrations of benzo[a]pyrene were found to exceed maximum permissible concentrations in all the samples, and the maximum recorded concentration exceeded the MPC by 50 times. Concentrations of other PAHs also exceeded the background values. The main soil pollutants were found to be fluoranthene, pyrene, benzo[b]fluoranthene, benzo[a]pyrene, and benzo[g, h, i] perylene, the part of which in the total content of PAHs was 65–80%.

Paramagnetic properties of humus acids of podzolic and bog-podzolic soils

The contents of free radicals in preparations of humic and fulvic acids extracted from virgin and plowed podzolic, surface gleyic podzolic, and peaty podzolic-gleyic soils were determined. The concentration of paramagnetic centers in the humic acids was 1.5–2 times higher than that in the fulvic acids. The agricultural use decreases the paramagnetic activity of the humus compounds and promotes the accumulation of biothermodynamically stable organic compounds in the plow horizons.

Complexation of mercury(II) ions with humic acids in tundra soils

The interaction mechanisms of mercury(II) ions with preparations of humic acids (HAs) isolated from organic horizons of surface-gleyed soils (Haplic Stagnosol (Gelic, Siltic)) of shrub tundra and hydromorphic peat gley soils (Histic Cryosol (Reductaquic, Siltic)) of moss-lichen tundra have been studied. The particular features of the interactions between the mercury(II) ions and the HAs are related to the molecular structure of the HAs, the mercury concentration range, and the environmental parameters. The fixation of mercury(II) ions into stable coordination compounds is most efficient in the pH range of 2.5–3.5. At the element concentrations below 0.50 μmol/dm3, the main complexing sites of HAs are their peripheral aminoacid functional groups. Pyrocatechol, salicylate, and phenolic groups from the nuclear moiety of molecules interact in the concentration range of 0.0005–0.50 mmol/dm3; the physical sorption of mercury hydroxo complexes by the surface of HAs is the main process occurring in the system.

Ecological-geochemical assessment of hydrocarbons in soils of Northeastern European Russia

The background contents of hydrocarbons (HCs) in soils of the far-northern and northern taiga of the Komi Republic were assessed. It was found that the soils of accumulative landscapes are enriched with HCs in comparison with the soils of eluvial landscapes. The differentiation of the HCs among the soil genetic horizons is more pronounced in the soils developed on loamy parent rocks (gley-podzolic and bog-podzolic soils) and less pronounced in the soils developed on sands (podzols and humus-illuvial bog-podzolic soils). The organic, litter, and illuvial horizons serve as a geochemical barrier in the pathway of the HC migration within the soil profile. A database for the mass fractions of HCs in the soils was created using GIS technologies, and a sketch map of the HC distribution in the soils was developed on its basis. The results obtained for the back-ground content of HCs are used for assessing the contamination of soils with oil and oil products and for gaining ecological expertise in the development of regional deposits of natural resources (raw hydrocarbons).

Molecular composition of raw peat and humic substances from permafrost peat soils of European Northeast Russia as climate change markers

Humic substances (HSs) from the mire peat soils of the forest-tundra zone of the European northeast part of Russia have been characterized in terms of molecular composition. This was accomplished using solid-state 13C nuclear magnetic resonance (13C NMR) techniques and electron spin resonance (ESR) spectroscopy. The composition depended on the intensity of cryogenic processes in the active layer, the quality of the humification precursors (the degree of peat material transformation), and the biochemical selection of aromatic fragments during humification. Humic acids (HAs) and fulvic acids (FAs) of the peat soils showed the presence of compounds with a low extent of condensation and a low portion of aromatic fragments, which increased with depth. A higher proportion of aliphatic carbon species was found in the HAs, indicating a low degree of organic matter stabilization. Based on the data from the two types of peat soils, we suggest that particular changes in the proportion of aromatic and unoxidized aliphatic fragments on the border of the bottom of the active layer and permafrost layers can be used as markers of current climatic change.

Polycyclic aromatic hydrocarbons in insular and coastal soils of the Russian Arctic

The content and individual component compositions of polycyclic aromatic hydrocarbons in polar soils of the Russian Arctic sector have been studied. The contamination of soils near research stations is identified from the expansion of the range of individual polycyclic aromatic hydrocarbons, the abrupt increase in the content of heavy fractions, and the accumulation of benzo[a]pyrene. Along with heavy hydrocarbons, light hydrocarbons (which are not only natural compounds, but also components of organic pollutants) are also accumulated in the contaminated soils. Heavy polycyclic aromatic hydrocarbons are usually of technogenic origin and can serve as markers of anthropogenic impact in such areas as Cape Sterligov, Cape Chelyuskin, and the Izvestii TsIK Islands. The content of benzo[a]pyrene, the most hazardous organic toxicant, appreciably increases in soils around the stations, especially compared to the control; however, the level of MPC is exceeded only for the soils of Cape Chelyuskin.

Hydrocarbons in the background soils of the southern- and middle-taiga subzones of the Komi Republic

The background content of hydrocarbons in soils of the southern and middle taiga has been assessed with consideration for the landscape and geochemical features of the area. Studies of hydrocarbons in soils of the taiga zone have showed that the position in the relief, particle-size distribution, and organic matter content are the main factors determining their content. The geochemical background of hydrocarbons is 50–100 mg/kg in the organic horizons of the soils on cover loams and 17–70 mg/kg in the soils on sandy deposits.

Study of polydispersity of humic substances by the gel chromatography method

Molecular weight distribution of humic and fulvic acid preparations extracted from podzolic, peaty podzolic weakly gleyed, and arable soils is investigated. The effect of the agricultural use of soils on the fractional composition of humic compounds is assessed.