In this study, high-performance liquid chromatography (HPLC) methods were utilised to identify and quantify C21–C33 n-alkanes in permafrost peatlands located within the Eastern European and Western Siberian cryolithozone. The total content of n-alkanes in Europe is 7.4 times higher compared to Siberian permafrost peatlands, and was estimated at 282 ± 145 (range from 74 to 709) μg/kg and 38 ± 12 (10–66) μg/kg, respectively. In the European cryolithozone, CPI alkane 9.5 ± 2.4 (3.7–18.6) and HPA 0.10 ± 0.03 (0.05–0.23) indicate a relatively higher share of higher plants and a higher stage of peat decomposition decree, with 6.9 ± 2.1 (3.1–12.9) and 0.15 ± 0.05 (0.06–0.29) in the Siberian region. In contrast, the Western Siberian peat plateaus were formed under conditions of constant excess moisture, a distinction from the Eastern European peatlands, where moisture and permafrost conditions were subject to constant change. This is further corroborated by the values of Paq, C23/C29 and C23(C27 + C31), which are 0.90 ± 0.05 (0.69–0.99); 11.1 ± 8.9 (0.84–61.6); 1.53 ± 0.80 (0.21–4.72) and 0.47 ± 0.12 (0.08–0.71); 0.64 ± 0.32 (0.08–1.48); and 0.43 ± 0.21 (0.04–1.26), respectively. The n-alkanes and peat physicochemical properties show no significant correlation. In the European part, permafrost degradation occurred repeatedly during the warming periods. Nevertheless, only slight subsidence of the permafrost table was observed, and peat continued to accumulate (up to 0.1 mm/year) in the West Siberian peat plateaus. Consequently, the variation in the quantitative and qualitative composition of n-alkanes in permafrost peatlands is determined not only by the different botanical composition of the plant remains forming the peat strata, but also by the consequence of lower mean annual temperatures in Western Siberia compared to the European nNortheast, and such a climatic difference persisted throughout the Holocene.

Vulnerability of peat plateaus to global warming was analyzed in northeastern European Russia. A laboratory experiment on artificial incubation of peat was carried out to analyze the resilience of organic matter of frozen peat bogs (palsas) to decomposition. The rate of mineralization of peat organic matter was calculated from data on the CO2 and CH4 emissions from the peat incubated at a temperature of +4°C under artificial aerobic and anaerobic conditions during 1300 days. Peat samples were taken from the active layer (AL), transitional layer (TL), and permafrost layer (PL). The δ13C and δ15N isotopes and the C/N, O/C, and H/C ratios were determined as indicators of change in the decomposition rate of organic matter. By the 1300th day of the experiment under aerobic conditions, the total CO2 amount released from the analyzed samples (per 1 g of carbon) was 10.24–37.4 mg C g–1 (on average, 25.76 mg C g–1), while under anaerobic conditions, it was only 2.1–3.38 mg C g–1 (on average, 3.15 mg C g–1). The CH4 emission was detected only in the peat from the transitional layer in very small quantities. The incubation experiment results support the hypothesis that peat plateaus are resilient, especially under anaerobic conditions, regardless the ongoing climate warming.

Regional geographic patterns of distribution of permafrost-affected soils in dependence on the bioclimatic, geocryological, and lithological conditions are described for the eastern sector of the Pechora Lowland. The spatial distribution of permafrost-affected soils is considered within the framework of the patterns of permafrost formation and degradation in relation to climate and ecosystems suggested by Y. Shur and M. Jorgenson. Permafrost-affected, mainly gleyed soils underlain by climate-driven permafrost are widespread in the northern part of the region, where modern climatic conditions are favorable for the preservation of permafrost in mineral parent rocks. The share of these soils that are weakly resistant to thawing upon climate warming gradually decreases to the south. A larger part (up to 70

Выполнен географический анализ пространственной дифференциации почвенного покрова предгорных равнин северо-востока Европейской России. Выявлены географические закономерности распространения почв, дифференцированных по глубине залегания кровли многолетнемерзлых пород, с учетом биоклиматической и геокриологической зональности в регионе. Исследования проведены в типичной и южной тундре, лесотундре и крайнесеверной тайге со сплошным, прерывистым, массивно-островным и островным распространением многолетнемерзлых пород. При изучении почвенного покрова применили классификационные критерии, выделяющие мелкомерзлотные, среднеглубинные мерзлотные, глубокомерзлотные и немерзлотные (сезоннопромерзающие) почвы. Выявлено, что широтная смена геокриологических и биоклиматических условий сопровождается значительными пространственными изменениями почвенного покрова. Мелкомерзлотные и среднеглубинные мерзлотные почвы широко распространены в северной части региональной криолитозоны, глубокомерзлотные - в южной. Установлено, что при географическом анализе почвы региональной криолитозоны целесообразно разделять на группы профилей: мерзлотные с близким залеганием многолетнемерзлой кровли, сезоннопромерзающие почвы с заглубленным залеганием многолетнемерзлой кровли и сезоннопромерзающие почвы на талых почвообразующих породах. В северной лесотундре в условиях массивно-островного распространения многолетнемерзлых пород резко снижается доля мерзлотных почв с близким залеганием многолетнемерзлой кровли. Значительное снижение доли почв, функционирующих на заглубленных многолетнемерзлых породах, наблюдается южнее - в крайнесеверной тайге с островным распространением многолетнемерзлых пород. Сделан вывод, что почвообразующие породы в значительной мере определяют пространственную дифференциацию мерзлотных почв, особенно в северной части региональной криолитозоны, а растительный покров во многом определяет распространение мерзлотных почв в южной криолитозоне. A geoinformation analysis of the spatial differentiation of the soil cover of the piedmont plains in the northeastern part of European Russia has been carried out. Geographical distribution patterns of soils differentiated by the active layer thickness have been identified, taking into account the bioclimatic and geocryological zoning in the region. The studies were carried out in typical and southern tundra, forest-tundra and northernmost taiga with continuous, discontinuous, massive-island and island distribution of permafrost. In studying the soil cover, classification criteria were used, which distinguished shallow and medium-depth permafrost, deep-permafrost and non-permafrost (seasonally freezing) soils. Latitudinal changes in geocryological and bioclimatic conditions are accompanied by significant spatial changes in soil cover. Shallow and medium-deep permafrost-affected soils are widespread in the northern part of the regional permafrost zone, and deep-permafrost soils are widespread in the southern part. When analyzing the soil cover geographically, it is advisable to divide the soils of the regional permafrost zone into groups of profiles: permafrost-affected soils with a shallow occurrence of the permafrost table, seasonally freezing soils with a deep occurrence of the permafrost table, and seasonally freezing soils on thawed soil-forming deposits. In the northern forest-tundra, under conditions of massive island permafrost distribution, the proportion of permafrost-affected soils with a shallow permafrost table is sharply decreased. A significant decrease in the portion of soils functioning on deep permafrost is observed further south, i.e. in the northernmost taiga with an island permafrost distribution. Soil-forming deposits largely determine the spatial differentiation of permafrost-affected soils, especially in the northern part of the regional permafrost zone. Vegetation cover largely determines the distribution of permafrost-affected soils in the southern permafrost zone.

Soil temperature measurements obtained at the site in the Bolshezemelskaya tundra with different landscape conditions are considered. Two methods of analytical description are considered: (1) with the help of one harmonic function and (2) with a breakdown into two periods—winter and summer (two piecemeal-continuous functions with different vibration amplitudes for each period separately). The amplitude of the oscillations for each method and period is calculated by least squares. It has been established that in winter and summer periods the amplitude of fluctuations is significantly different for all the considered landscape conditions. Disclosed is a method of describing the temperature regime of soils taking into account this division, which is compared with average values for each period separately. Comparison of calculated and observed values for winter period shows almost complete coincidence. Accordingly, this method of description can be used to recover data over a small missed time interval of the order of a month, as confirmed by the results of calculations for the summer period. The smallest difference between winter and summer oscillation amplitudes is noted for peat soils.

Specific features of the morphology, properties, and temperature regimes of soils functioning in two different drained lake basins of the Bol’shezemel’skaya tundra are characterized. The basins differ significantly in the features of landscape evolution, the composition of bottom (soil-forming) sediments, and the patterns of the soil and plant covers. Soils in the naturally drained basin with mineral (sandy and clayey) bottom sediments are assigned to the orders of gley, and weakly developed soils that are also typical of watershed landscapes in the studied region. These are ecosystem-modified permafrost-affected soils that are partially protected from thawing. They have an acid reaction, low base saturation, and moderate carbon content in the mineral horizons. In the artificially drained basin with a silty peat layer of bottom sediments, peat permafrost-affected soils, including specific peat soils under tundra meadows, are developed. Permafrost peat soils of the former lake bottom are ecosystem-protected from thawing and are characterized by the high ash content and slightly acid reaction. The studied soil parameters are significantly differentiated with respect to lake basins, which is determined by the composition of parent materials, specific features of landscape development, and activity of modern cryogenic processes.

Permafrost degradation due to climate warming is currently observed in the northeastern part of European Russia. Peat plateaus underlain by permafrost cover only about 20% of the Russian European cryolithozone but contain almost 50% of soil organic carbon stocks (SOC), which are considered to be vulnerable to microbial mineralization after permafrost thaw. The current study was performed at three key sites of peat plateaus located along the southern permafrost limit. SOC decomposition was studied by aerobic and anaerobic incubation experiments, conducted at 4 °C over a period of 1301 days. The CO2 production was measured in peat samples at three key sites from the active layer (AL), transitional layer (TL), permafrost layer (PL), and at one site from the deep permafrost layer (DPL), which is in contact with mineral soil at 3.7 m depth. During the experiment, the initial СО2 respiration rates significantly differed in the samples AL, TL and PL in all key sites. However, at each site in the majority of samples the CO2 respiration rates were 2-5 times aerobically higher than anaerobically. In anaerobic conditions, in all sites, the СО2 respiration rate in PL was the lowest, higher in TL and the highest in AL in all 3 sites. Projections of CO2 aerobically production for 80 years represent 1.44 ± 0.11, 6.31 ± 0.47, 30.64 ± 17.98% of initial permafrost carbon from the samples of Inta 1, Inta 11 and Kolva respectively. But under anaerobical conditions estimates are close and indicate insignificant amounts 0.30…1.90% of carbon release over a period of 80 years. We suggest that even under ideal conditions of the incubation experiment, without considering ecological inertia under natural conditions, while also permafrost temperature is close to zero, greenhouse gas release from initial SOC is significantly less than estimated.

A comparative analysis of remote spectral indices has been carried out during the study of changes in the vegetation cover in the postagrogenic biogeocenoses of the Bolshezemelskaya tundra. Successional changes in the species composition of vegetation have been considered to estimate the dynamics of the spectral indices in the meadow biocenoses throughout the agricultural and postagrogenic periods. The spectral characteristics and species composition of vegetation in the surrounding undisturbed biocenoses were used as background indicators. Compared to the surrounding background sites, meadow biogeocenoses used for agriculture had relatively high indices, characterizing the moisture and photosynthetic activity of plant phytomass (NDVI, LWCI, NDMI, and channel B5). Changes in the amount of dead biomass were estimated using the PSRI index, the values of which were minimal during the period of agricultural use of the meadows with regular haying. During self-recovery succession in postagrogenic biogeocenoses, the values of the spectral indices gradually reach the level characteristic of the surrounding background sites. During the postagrogenic period, the LWCI, NDMI, and NDVI values gradually decrease and the values of PSRI and spectral channel B3 increase in meadow biogeocenoses. During the postagrogenic period, sown grass herbage thins out in meadow biogeocenoses, a shrub layer is formed, and species that penetrate from the surrounding communities become dominant and subdominant. The self-recovery of tundra vegetation in postagrogenic biogeocenoses was activated during the period of current climate warming. The effect of climate on the spectral indices was assessed based on the statistical relationships between the values of the climate characteristics and spectral indices in postagrogenic and background biogeocenoses.

The results of the application of geo-radar profiling for the study of soils and underlying rocks of polygonal bogs of the Pur-Taz interfluve (North of Western Siberia), functioning in natural and anthropogenic disturbed conditions, are presented. The research area belongs to the southern tundra with a predominantly continuous distribution of permafrost rocks. The construction of highways in the North of Russia is one of the main factors of anthropogenic impact on the tundra geosystems of the cryolithozone, affecting the temperature regimes of soils and the depth of permafrost. The features of spatial differentiation of the depth of occurrence of permafrost rocks on the site of polygonal swamps intersected by a federal highway were determined by the methods of geo-radar profiling. Georadiolactic profiling made it possible to determine the configuration of the depth of the permafrost roof both in natural and anthropogenic disturbed areas of polygonal swamps. The maximum lowering of the permafrost roof is determined at the base of the road embankment and does not exceed a depth of three meters. Despite the deep occurrence of the MMP roof under the road embankment, the thickness of the thawed buried peat horizons here is similar to that of the seasonally shallow layer of undisturbed peat polygons. The features of spatial differentiation of the depth of the permafrost roof in the polygonal swamps intersected by the bulk highway in the North of Western Siberia are similar to those characteristic of regions with a continuous low-temperature cryolithozone. The method of manual probing of the permafrost roof was used to verify the results of geo-radar profiling within undisturbed areas.

The field ecosystem studies of researchers by Komi Federal Research Center in the area of the proposed construction of solid industrial and household waste landfill (ecotechnopark "Shies", near railway station Shies, Arkhangelsk Region) have revealed limitations and possible potential risks in the implementation of the project. The characteristics of soil and vegetation cover, features of the chemical composition of surface waters (high content of Fe, Mn, Zn, Cu related with swamping and peat water saturation) of the area were established on the territory. The peat thickness according to geo-radar sounding at bogs exceeds 1.5-2.0 m. Thematic mapping of the work areas based on the materials of modern and archival satellite images demonstrates the ratio of the areas of the dominant landscape complexes and classes of vegetation cover. A model of potential atmospheric circulation and transfer of pollution was made for the assumed source of atmospheric emission. The identified limitations are mainly associated with a high watering of the territory and the dominance of old-growth spruce stands with the presence of indicator species of intact areas, often including rare species of plants, animals and lichens of different levels of protection. Four species of lichens included in the Red Book of the Russian Federation (2008) are presented at the planning polygon area. There is a probability to meet with representatives of 15 species of rare and protected animals. A preliminary calculation of damage to the environment shows that loss of ecosystem services exceeds the economic benefits.

Nitrous oxide (N2O) emissions from permafrost-affected terrestrial ecosystems have received little attention, largely because they have been thought to be negligible. Recent studies, however, have shown that there are habitats in the subarctic tundra emitting N2O at high rates, such as bare peat (BP) surfaces on permafrost peatlands. Nevertheless, the processes behind N2O production in these high-emission habitats are poorly understood. In this study, we established an in situ 15N-labeling experiment with two main objectives: (1) to partition the microbial sources of N2O emitted from BP surfaces on permafrost peatlands and (2) to study the fate of ammonium and nitrate in these soils and in adjacent vegetated peat (VP) surfaces showing low N2O emissions. Our results confirm the hypothesis that denitrification is mostly responsible for the high N2O emissions from BP. During the study period, denitrification contributed ∼ 79 % of the total N2O emissions from BP, whereas the contribution from ammonia oxidation was less (about 19 %). Both gross N mineralization and gross nitrification rates were higher in BP than in VP, with high C/N ratios and a low water content likely limiting N transformation processes and, consequently, N2O production in the latter soil type. Our results show that multiple factors contribute to high N2O production in BP surfaces on permafrost peatlands, with the most important factors being the absence of plants, an intermediate to high water content and a low C/N ratio, which all affect the mineral-N availability for soil microbes, including those producing N2O. The process understanding produced here is important for the development of process models that can be used to evaluate future permafrost–N feedbacks to the climate system.

Northern peatlands, which are crucial reservoirs of carbon and nitrogen (415 ± 150 and 10 ± 7 Pg, respectively), are vulnerable to microbial mineralization after permafrost thaw. This study was carried out in four key sites containing northern permafrost peatland, which are located along the southern cryolithozone. The aim of this study is to characterize amino acids and the microbial community composition in peat strata along a climate gradient. Amino acids and microbiota diversity were studied by liquid chromatography and a quantitative polymerase chain reaction. The share of amino acid fragments was 2.6–7.8, and it is highly significantly correlated (r = 0.87, −0.74 and 0.67, p ˂ 0.05) with the organic nitrogen concentration in the soil, the C/N ratio, and δ15N. The data shows the existence of a large pool of microorganisms concentrated in permafrost peatlands, and a vertical continuum of bacteria, archaea, and microscopic fungi along the peat profile, due to the presence of microorganisms in each layer, throughout all the peat strata. There is no significant correlation between microorganism distribution and the plant macrofossil composition of the peat strata. Determining factors for the development of microorganism abundance are aeration and hydrothermal conditions. The availability of nitrogen will limit the ability of plants and microorganisms to respond to changing environmental conditions; however, with the increased decomposition of organic matter, amino acids will be released as organic sources of nitrogen stored in the protein material of peat-forming plants and microbial communities, which can also affect the organic nitrogen cycle.

Effects of permafrost aggradation on greenhouse gas (GHG) dynamics and climate forcing have not been previously quantified. Here, we reconstruct changes in GHG balances over the late Holocene for a sub-arctic peatland by applying palaeoecological data combined with measured GHG flux data, focusing on the impact of permafrost aggradation in particular. Our data suggest that permafrost initiation around 3000 years ago resulted in GHG emissions, thereby slightly weakening the general long-term peatland cooling impact. As a novel discovery, based on our chronological data of bare peat surfaces, we found that current sporadic bare peat surfaces in subarctic regions are probably remnants of more extensive bare peat areas formed by permafrost initiation. Paradoxically, our data suggest that permafrost initiation triggered by the late Holocene cooling climate generated a positive radiative forcing and a short-term climate warming feedback, mitigating the general insolation-driven late Holocene summer cooling trend. Our work with historical data demonstrates the importance of permafrost peatland dynamics for atmospheric GHG concentrations, both in the past and future. It suggests that, while thawing permafrost is likely to initially trigger a change towards wetter conditions and consequent increase in CH4 forcing, eventually the accelerated C uptake capacity under warmer climate may overcome the thaw effect when a new hydrological balance becomes established.

This paper presents results from long-term active layer monitoring at four CALM sites in the Russian European North. Observational records range from 10 to 24 years in length (1996-2019). The impact of climatic and landscape parameters on active layer thickness has been assessed through linear regression. The temporal dynamics of climatic parameters, responsible for the thaw depth changes, were investigated. The long-term data indicate that the active-layer thickness has increased at all the monitoring sites, in response to changes in both summer and winter climatic parameters. The surface organic layer also serves as a major landscape factor influencing spatial patterns of thaw depth and climate-induced rates of permafrost thawing.

Based on the data of the plant macrofossil and palynological composition of the peat deposits, the evolution and current state of polygonal peatlands were analyzed at the southern limit of continuous permafrost in the Pur-Taz interfluve. Paleoreconstruction shows that peat accumulation began in the Early Holocene, about 9814 cal. year BP, in the Late Pre-Boreal (PB-2), at a rate of 1 to 1.5 mm year−1. Intensive peat accumulation continued in the Boreal and early Atlantic. The geocryological complex of polygonal peatlands has remained a stable bog system despite the predicted warming and increasing humidity. However, a rather rapid upper permafrost degradation and irreversible changes in the bog systems of polygonal peatlands occur with anthropogenic disturbances, in particular, a change in the natural hydrological regime under construction of linear objects.

The concentrations of 15 individual PAHs in 93 peat cores have been determined by using high-performance liquid chromatography methods. In the profile the qualitative and quantitative composition of PAHs was non-uniform estimated in a wide range: from 112 to 3673 ng/g with mean 1214 ± 794 ng/g. Among 15 identified individual PAHs, the main contribution to their total amount was made by heavy highly condensed PAHs in the Eastern European peat plateaus, in particular, 6-nuclear benzo[ghi]perylene (1021 ± 707 ng/g), whereas in West Siberian permafrost peatlands, light PAHs were dominating, mostly naphthalene and phenanthrene (211 ± 87 and 64 ± 25 ng/g, respectively). The grass-equisetum peat contained the maximum of heavy PAHs and the dwarf shrub-grass—the minimum. In grass-dwarf shrub, grass-moss and moss peat, the share of 2-nuclear PAHs was most significant: naphthalene and fluorene, as well as 6-nuclear benzo[ghi]perylene. The presence of benzo[ghi]perylene in the entire peat strata, including its permafrost layer, was a marker of the anaerobic conditions that persisted throughout the Holocene and they were necessary for the synthesis of this compound.

In 2016, an outbreak of anthrax killing thousands of reindeer and affecting dozens of humans occurred on the Yamal peninsula, Northwest Siberia, after 70 years of epidemiological situation without outbreaks. The trigger of the outbreak has been ascribed to the activation of spores due to permafrost thaw that was accelerated during the summer heat wave. The focus of our study is on the dynamics of local environmental factors in connection with the observed anthrax revival. We show that permafrost was thawing rapidly for already 6 years before the outbreak. During 2011-2016, relatively warm years were followed by cold years with a thick snow cover, preventing freezing of the soil. Furthermore, the spread of anthrax was likely intensified by an extremely dry summer of 2016. Concurrent with the long-term decreasing trend in the regional annual precipitation, the rainfall in July 2016 was less than 10% of its 30-year mean value. We conclude that epidemiological situation of anthrax in the previously contaminated Arctic regions requires monitoring of climatic factors such as warming and precipitation extremes.

The computational setup of assimilation andreanalysis of measurement data on temperature of the upper ground layerand active layer thickness based on the models of various complexity isformulated. A need in applying a dynamic model for this purpose issubstantiated. Four types of permafrost with different active layerthickness are distinguished. The model validation based on measurementdata in northern European Russia and Eastern Siberia is carried out forthese permafrost types. A method for taking into account the small-scalevariability of soil, vegetation, and landscape factors based on theensemble simulations is proposed. It is shown that the dynamic modelsimulates well measurement data on the active layer thickness for a widerange of landscape, soil, and climate conditions and can be used for thereanalysis of permafrost data.