Turbic Cryosols Research Articles

Carbon Dioxide Emission from Soils of the Ecotone Zone in the North of Western Siberia

The study area in the north of Western Siberia is located in the southern tundra–taiga ecotone near the southern boundary of discontinuous permafrost zone. Three contrasting ecosystems—pine forests with Albic Podzols; palsa with Histic Oxyaquic Turbic Cryosols, and bogs with Fibric Histosols—predominate in this area. The objectives of the study included evaluation of the CO2 emission from soils in the growing seasons of 2019–2022 and analysis of the factors controlling spatial and interannual variability of the emission. The study included analysis of the soil respiration (static closed chamber method) data and soil hydrothermal parameters in August for four years. In the absence of definite trends in climatic parameters over the past 10 years, a gradual increase in the soil temperature in all ecosystems and an increase in the depth of summer thawing in palsa were observed. These changes were not accompanied by significant changes in the CO2 emission. Its averaged values varied from 485 to 540 mg CO2/(m2 h) in forest ecosystems and from 150 to 255 mg CO2/(m2 h) in the palsa–bog complex with high coefficients of spatial variability. High CO2 emission in forest ecosystems is determined by a favorable hydrothermal regime, high root biomass, and good water-physical properties. Part of the CO2 produced by palsa soils is transported with suprapermafrost water flows toward the adjacent bog and is released from the surface of bog soils. Soil temperature interrelated with seasonal thawing depth proved to be a significant predictor of the spatial variability of CO2 emission from the soils of the palsa–bog complex.

CO<sub>2</sub> Emission by Soils of the Ecotone Zone in the North of Western Siberia

The study area in the North of Western Siberia is located at the southern limit of the distribution of surficial permafrost in the ecotone zone on the border of taiga and southern tundra. Area is characterized by the contrasting landscapes: pine forests with Albic Podzol; palsa with Histic Oxyaquic Turbic Cryosol and bog ecosystems with Fibric Histosol. The objectives of the study included evaluation the values of CO2 emission (SR) by soils of key landscapes in the growing seasons of 2019–2022, and evaluation the factors of spatial variability of this indicator and its interannual variability. The study included analysis of the RS database (static closed chamber method) and soil hydrothermal parameters for four years in August. In the absence of trends in changing climatic parameters over the past 10 years, a gradual increase in soil temperature in all landscapes and an increase in the depth of thawing in palsa were observed. These changes were not accompanied by significant changes in the SR value. It averaged from 485 to 540 mgCO2/(m2 h) in forest ecosystems, from 150 to 255 mgCO2/(m2 h) in the peat-bog complex with high coefficients of spatial variability. High values of SR in forest ecosystems are determined by a favorable hydrothermal regime, high reserves of root biomass, and good water-physical properties. Part of the CO2 produced by palsa soils is transported by supra-permafrost waters and released from the surface of bog soils. Soil temperature, regulated by seasonal thawing, was a significant predictor of the spatial variability of SR on the soils of the palsa-bog complex.

Thermal simulations on periglacial soils of the Central Andes, Argentina

AbstractRock glaciers are the most common landforms of the Andean periglacial landscape in the Central Andes of San Juan, Argentina. Their active layer is gravelly with a typical openwork structure. The upper parts of these rock glaciers are coarse‐grained Turbic Cryosols, with no vegetation cover. Since March 2018, coarse soils in the active layer of the “Candidato” rock glacier have been monitored (31.9°S, 70.18°W). Three trenches, 4,000 m a.s.l. and down to a depth of 90 cm, were equipped with sensors to measure soil temperature and volumetric water content. We also measured particle size distributions and calculated thermal properties from soil samples. The mean thermal conductivities for unfrozen and frozen soils were 0.69 and 0.54 W m−1 K−1, respectively, and the mean thermal diffusivities were 2.05 × 10−7 and 1.64 × 10–7 m2 s−1, respectively. Analysis of the seasonal thermal and hydrological fluxes in the active layer is challenging, as the physical properties change cyclically, thus controlling processes such as water storage, infiltration and seepage, heat balance, mechanical behavior, and kinematic response. We used the Coupled Heat and Mass Transfer Model for the Soil–Plant–Atmosphere System (COUP) numerical computerized model, performing a site‐specific calibration, to simulate soil temperatures, active layer thicknesses, and seasonal freezing–thawing depths. The model implemented, in combination with a reanalysis of the meteorological data series, performed very well to reproduce the data from thermo‐sensors placed in the ground. This proposed methodology is viable for areas with limited instrumentation or low accessibility. The “Candidato” rock glacier can be used as a pilot model for thermal modeling purposes on rhyolitic rock glaciers in the region.

Soil contamination by diesel fuel destabilizes the soil microbial pools: Insights from permafrost soil incubations

Arctic contamination by diesel fuel (DF) is of great concern because of the uncertain feedback of permafrost carbon (C) and soil microbiota to DF in the context of climate change in high latitudes. We conducted a laboratory incubation experiment with a gradient of DF addition ratios to examine the responses of the soil microbiota of the typical permafrost soils in the tundra ecosystems of the Norilsk region (Siberia). The study revealed initial heterogeneity in the microbial activity of the studied soils (Histic Gleyic Cryosols (CR-hi,gl), Turbic Cryosols (CR-tu), Turbic Spodic Folic Cryosols (CR-tu,sd,fo), Gleyic Fluvisols (FL-gl)). We applied the two-pool model for evaluation of the effect of DF on the proportions of C pools and revealed significant differences between soil types in the fast and slow C pools in response to DF addition. The results showed that DF addition treatments had varying effects on the fast and slow C pools, microbial activity, and microbial community structure in the studied soils. For minor exceptions, DF dramatically accelerated C loss from the slow C pool in all soil types. We assume that differences in C pool and microbiota responses to DF addition were caused by soil texture and changes in microbial community structure. We isolated Serratia proteamaculans, S. liquefaciens, S. plymuthica, Rhodococcus erythropolis, Pseudomonas antarctica, P. libanensis, P. brassicacearum, and P. chlororaphis from the DF-polluted soils. These species are recommended for bioremediation to mitigate the DF contamination of permafrost soils, especially regarding climate change and the sustainable well-being of Arctic ecosystems.

Soil orders and their areas on the updated soil map of the Russian Federation, 1 : 2.5 M scale

An analysis of the soil cover of Russia as presented on the soil map on a scale of 1 : 2.5 M with the use of a new substantive-genetic soil classification system has been performed at the level of soil orders. The high level of classification-based generalization makes it possible to assess the most general patterns of soil geography and soil resources and to identify changes that have occurred as a result of renaming of each polygon on the map with the use of the new classification. The areas occupied by soil orders have been calculated. In total, there are 24 soil orders on the new map, including 21 orders of natural soils and 3 orders (agrozems, turfzems, stratozems) of anthropogenically transformed soils. Soils of the orders of agro-abrazems, chernozems, and turbozems are not presented on the map. As on most small-scale soil maps of Russia, the zonal regularities of the soil cover in the East European Plain and high lithogenic mosaicity in Central and Eastern Siberia are clearly seen. The new map includes soil orders that were absent on the initial map: cryozems, cryometamorphic and hydrometamorphic soils, lithozems, cryoabrazems, cryoturbozems, urbostratozems, and organo-accumulative soils. Soils characteristic of humid conditions predominate: Al-Fe-humus soils (Podzols) (319.2 M ha, or 19% of the land fund of Russia), gley soils (Gleysols) (223.9 M ha, 13%), texture-differentiated soils (Luvisols and Regosols) (190.8 M ha, 11%), and peat soils (Histosols) (143.5 M ha, 8%) and occupy more than a half of the territory of Russia. The area of humus-accumulative soils most suitable for arable use is 103.6 M ha (6%). Considerable areas are occupied by soils of the orders of cryozems (Turbic Cryosols) (111.4 M ha), iron-metamorphic soils (Chromic Cambisols) (92.7 M ha), structure-metamorphic soils (Cambisols) (47.3 M ha), pale-metamorphic soils (Cambic Cryosols) (12.8 M ha), hydrometamorphic soils (Calcic Gleysols) (4.3 M ha), and cryometamorphic soils (Cambisols Gelic) (3.4 M ha), which corresponds to the vast continental territory of Russia with balanced moisture conditions. Separate place belongs to the soils with strict limitations for use (lithosols (Leptosols), weakly developed soils (Regosols, Nudilithic Leptosols)) but playing important biospheric functions and requiring special protection.

Structural organization and composition peculiarities of soil neoformations in some types of automorphic soils in the southeast of the Bolshezemelskaya tundra

Automorphic tundra soils of different gleying degree and various permafrost table depth were studied. The chemical composition and distribution of different structural components, including skeletans (sandy-silty cutans), clay cutans, and Fe-Mn concretions in Dystric Cambisol and Turbic Cryosol profiles (permafrost table occurs 2–5 m and 0.9 m depth) were investigated. It is shown that the upper part of the profile of Dystric Cambisol forms under the current active processes of pedogenesis (gleying, Al-Fe-humus illuviation, specific cryogenic organization), signs of previous stages of soil genesis are preserved (the presence of humus pedorelicts, fragments of clay deposits) in the lower part. The chemical composition of the intraped mass reflects the eluvial-illuvial differentiation of Dystric Cambisol profile. The maximum amount of Fe-Mn concretions is observed in the middle profile part. This is due to redox processes in this type of soil. Turbic Cryosols is characterized by insignificant profile differentiation of structural components by chemical composition, weak intensity of pedogenic processes, cryoturbations, inherited signs of earlier stages of pedogenesis (fragments of clay cutans, humus pedorelicts) in the lower horizons. Gleying is one of the leading soil-forming processes. Cryogenic transformation of the soil layer affects the distribution of small amount of skeletans and concretions.

Degradation of Arable Soils in Central Yakutia: Negative Consequences of Global Warming for Yedoma Landscapes

Global warming, which is especially intensive (up to 0.08°C yr−1) in permafrost area of Central Yakutia, has dramatic consequences for scarce arable land resources in this region. In Yedoma landscapes, intense permafrost thawing on arable fields unprotected by forest vegetation transforms the surface microtopography with the formation of residual thermokarst mounds (byllars) of 6–10 m in diameter surrounded by a polygonal network of hollows of 0.3–1.5 m in depth above melting ice wedges. This process also takes place on former croplands abandoned in the recent decades because of socioeconomic reasons. It is accompanied by a significant transformation of the previously highly likely homogeneous soil cover composed of Cambic Turbic Cryosols (Sodic) into differentiated complexes of permafrost-affected Stagnic Cambisols or Calcic Solonetzes (Turbic) on the mounds and Calcic Stagnic Solonetzes (Turbic) in the microlows. Surface soil horizons on the mounds have a strongly to very strongly alkaline reaction (pH 8.5–9.5) and low (<2%) organic carbon content; a wavy line of effervescence is found at a depth of 15–30 cm. Soils in the microlows have a close to neutral reaction in the upper horizons (pH 6.2–7.5); higher organic carbon content (2–3%); more pronounced textural differentiation of the profile with the formation of typical natric Btn and, in some cases, overlying eluvial E horizons; deeper (50–60 cm) line of effervescence; and clear stagnic features in the lower part of the profile. In the case of shallow embedding by ice wedge, the lowermost part of the soil in the microlow is characterized by the low bulk density (1.04 g cm−3) because of the appearance of hollows after thawing of the ice-rich transient layer and melting of the top of ice wedges. This may be indicative of the further soil subsidence in the future and the appearance of initial thermokarst lakes (dyuedya) within the Yedoma terrain with its transformation into the alas type of landscape. Rapid thermokarst-driven development of microtopography followed by differentiation of the soil cover with increasing soil alkalinity on the microhighs and soil textural differentiation and overmoistening of deep layers in the microlows prevents the return of abandoned arable land to agriculture in Yedoma landscapes.

Seasonal cryogenic processes control supra-permafrost pore water chemistry in two contrasting Cryosols

Over the last decades, Arctic landscapes have experienced intense warming leading to permafrost degradation and rapid ecosystem changes. Active layer thickening, widespread melting of ground ice and thermo-erosion have affected the mobilization of organic and mineral elements. While the carbon and nitrogen cycles are intensively studied, the soil weathering has been less documented. In the present study, we monitored the chemistry of soil capillary and gravitational pore waters, rainfall and stream waters daily during the growing season in two experimental sites under tussock tundra vegetation in the low-Arctic region, in Salluit (Nunavik, Canada). We aimed to investigate the seasonal thaw controls on the evolution of concentrations of major organic and inorganic elements in the active layer (i.e., seasonally thawed surface layers) of two permafrost soils (Cryosols) differing in parental materials: an ombrotrophic bog (i.e., Histic Cryosol) and post-glacial marine sediments continuously waterlogged (i.e., Turbic Cryosol). In the Histic Cryosol, the electrical conductivity was <100 µS cm−1 and Cl− and Na+ were the dominant soluble ions originating from atmospheric depositions. In the Turbic Cryosol, decarbonated in the first 40 cm, Ca2+ and Mg2+ were the dominant soluble ions in the capillary water reflecting the dissolution of soil minerals, while Cl− and SO42− dominated in gravitational water, illustrating inputs from uphill. In the two soils, Ca2+ and Mg2+ concentrations as well as Mg/Na and Ca/Na increased with depth. Along summer, the soil pore water chemistry evolved with thaw front and water table depths in the two sites. Particularly in the Histic Cryosol, electrical conductivity, solute concentrations, Mg/Na and Ca/Na ratios increased with the thaw front deepening. Our observations suggest that the active layer thickening and increasing supra-permafrost flow contribution, expected to increase with Arctic warming, could lead to a shift in chemistry of pore waters in organic and mineral permafrost soils, differently depending on permafrost landform settings.

Microbial Biomass, Carbon Stocks, and CO2 Emission in Soils of Franz Josef Land: High-Arctic Tundra or Polar Deserts?

The biomass of prokaryotes and fungi, organic carbon stocks, and CO2 emission were studied in the Cryosols and Leptosols of Franz Josef Land. The highest carbon stocks were found in the Eutric Leptosols (Loamic, Humic) formed in the wind-sheltered areas (23.2 kg C/m2 in the upper 50 cm), as well as in Turbic Cryosols (Humiс) that contained organic matter buried by cryoturbation (13.7–20.7 kg C/m2). The number of prokaryotes varied between 0.14 and 2.10 billion cells/g of soil, and the maximum values of their biomass were found in the litter. The fungal biomass varied from tens to hundreds of mg/g of soil depending on the type of soil and biotope. The share of spores was more than a half of the total fungal biomass in 80% of cases. Spores and mycelium were mainly represented by small forms with a diameter of up to 2–3 microns. The length of the fungal mycelium ranged from 4 to 272 m/g of soil. The maximum development of fungi was observed in the lichen biocrusts and moss litters. The fungal biomass decreased exponentially with the depth of horizons, and at the same time the share of prokaryotes in microbial biomass increased by several times. The share of microbial carbon in the total organic carbon was higher in soils of barrens (the most extreme habitats among the studied ones) as compared with the soils of local tundra areas (12.7 versus 2.5%, respectively). The levels of СО2 emission from the surface of undisturbed soils varied in the range of 1.6–91.7 mg C–CО2/m2 per hour and differed by tens of times between barrens and tundra areas. The studied soils are close to the soils of the Arctic tundra when compared by their carbon stocks and CO2 emission values; however, their microbial biomass values and their distribution are close to the soils of Antarctica and hot deserts.

Cryogenic soils near the Yeletsky settlement, northeast of the Komi Republic

The subject of this research is the soils and soil-geochemical catenae in the area of Yeletsky settlement, located in the northeast of the Komi Republic. Catena were deposited on the mound covered with moss-shrub tundra transect from the interfluve of Usa and Yelets Rivers to a lacustrine depression, complicated by arching permafrost mounds. Within the district of research, the authors laid five soil incisions (EL20-P1, EL20-P2, EL20-P3, EL20-P4 and EL20-P5) that formed a soil-geochemical catena along the slope. Complex land cover found at the periphery. The explored soils were formed on silty loams with permafrost horizon at a depth of 0.5-0.7 m and belong to Cryosols, Turbic Cryosols and Histic Gleysols. Cryosols in the upper part of catena show specific cryogenic granular structure due to lack of soil moisture content. The soils on the slope and in the depression are more saturated with water; therefore, structureless Turbic Cryosols and Histic Gleysols are formed. In the soil horizons, the values of pH and electrical conductivity were measured, the content of organic carbon and soil texture were studied. An increase in soil acidity on organogenic zones by 4.3 - 5.7 was noticed; in underlying horizons the pH values reach 6.9.

Suprapermafrost Horizons of the Accumulation of Raw Organic Matter in Tundra Cryozems of Northern Yakutia

In the profiles of cryozems (Oxyaquic Turbic Cryosols) developing in tundra of northern Yakutia under conditions of shallow active layer, suprapermafrost horizons of the accumulation of raw organic matter are formed. Taking into account their genesis, stable and regular position in the soil profile, paragenetic links with the overlying horizons and neighboring soil profiles, and a set of diagnostic features and properties, these horizons can be separated as a new type of genetic soil horizons—the organomineral accumulative suprapermafrost horizon (CRO). Its qualitative composition (the ratio of organic and mineral matter in the material) can be reflected at a lower level. In relation to the separation of the new genetic horizon within the framework of the new Russian soil classification system, a new genetic types of soils—cryozem with suprapermafrost accumulation of raw organic matter (suprapermafrost organo-accumulative cryozem)—can be established. Its diagnostic profile has the following horizonation: (O, AO, T)–CR–CRO–┬C.

Свойства и минералогический состав темногумусовой квазиглеевой солончаковой солонцеватой криотурбированной мерзлотной почвы Баргузинской котловины (Бурятия)

Morphological, physical-chemical properties, texture, salt composition mineralogical composition of the particle-size fractions 5 mkm of dark-humus quasigleyic solonchakous solonetzic cryoturbated deeply permafrost loamy-sandy soil developed from alluvial sediments (Salic Mollic Reductaquic Turbic Cryosol (Eutric, Loamic, Calcaric, Fluvic, Sodic)) are presented. The soil is situated at the northern-eastern part of Barguzin Depression in the impact zone of dumping of nitrogen siliceous thermal underground waters of Kuldur type (Kuchiger springs). The soil forms from materials of disintegration of high-content-potassium calcareous-alkali granites of Barguzin complex of Angara-Vitim Batholith. It was found soil salinity of weak to very strong degree, presumably sulfate-sodium with gypsum. There is a net of gypsum filaments in the solum that is observed by morphological analysis. Low amount of rectorite was found in clay fraction of undisturbed layers of alluvium at the depth of 54-145 cm in the studied soil profile. Regular structure of rectorite comprised mica (A) and smectite (B) packets with alternation motive ABAB… is transformed into irregular structure of mica-smectite interstratifications by impact of soluble sodium salts and cryoturbation of soil material in soil horizons at the depth of 0-54 cm formed from the alluvium. Regional peculiarity of studied soil is small shear of quartz in silt and sand fractions that is a result of mineral composition of biotite and amphibole-biotite granites and granitoids. Irregular mica-smectite interstratifications with high shear (>50%) of smectite packets are destroyed by impact of sodium sulfate and hydrocarbonates hydrogenic accumulation in the solum and are partially illuviated into middle part of soil profile with formation of humus-clay cutans on the lateral sides of aggregates by infiltration of rain waters. Existence of humus-clay cutans is an evidence of weak degree of solonetzic process.

Mineralogy and chemical composition of Cryosols and Andosols in Antarctica

Variations in mineralogical and elemental composition of Turbic Cryosol (King George Island and James Ross Island), Skeletic Cryosol (J. Ross Island, the Trinity Peninsula), Leptic Andosols (Deception Island), and Skeletic Andosols (Deception Island) were studied. Significant differences in mineralogical composition in size fraction, vertical and horizontal position were determined by X-ray diffraction quantitative analysis. The differences were attributed to a variable degree of chemical weathering process. As a product of weathering were defined montmorillonite, chlorite, microcrystalline polymorphous silica, Fe oxides, and oxyhydroxides. Their content was increased towards the surface and in a finer fraction. Crystal thickness and size distribution of montmorillonite was measured by the Bertaut-Warren-Averbach technique and the results confirmed higher intensity of chemical weathering in Turbic Cryosols (J. Ross Island and King George Island). Feldspars and volcanic glass were the main phases found in soil samples from Deception Island. They were determined as phases of parent rock and indicated low intensity of chemical weathering. Clinoptilolite was identified in soil samples from J. Ross Island and Deception Islad and its hydrothermal origin was supposed. Soil (sample AP) from Base General Bernardo O’Higgins Riquelme had significantly higher content of phosphate minerals, which was a result of ornithogenic activities. Macro elements content was consistent with mineralogical analyses. Turbic Cryosols were rich in iron, aluminium, magnesium, and manganese (&amp;gt; 2%). Skeletic Cryosols contained also iron, aluminium, magnesium, manganese, calcium, and sulphur (&amp;gt; 1%). Leptic Andosols were rich in iron and aluminium (&amp;gt; 2%). Soil properties and humic substances quality were evaluted. Results of chemical and physical analyses indicated that poorly developed soils of Antarctica varied in acidity, conductivity, humus content, and texture. Humic substances content and quality were low. Mainly mechanical (physical) and chemical weathering processes played major role in the soil development accompanied by low intensity of biological activity.

Adsorption of water vapour and the specific surface area of arctic zone soils (Spitsbergen)

AbstractWater vapour/nitrogen adsorption were investigated and calculated the specific surface areas of arctic-zone soil samples (Turbic Cryosols) originating from different micro-relief forms (mud boils, cell forms and sorted circles) and from different depths. For the characterisation of the isotherms obtained for arctic soils, the Brunauer-Emmet-Teller model was then compared with the two other models (Aranovich-Donohue and Guggenheim-Anderson-de Boer) which were developed from Brunauer-Emmet-Teller. Specific surface area was calculated using the Brunauer-Emmet-Teller model at p p0−1range of 0.05-0.35 for the water vapour desorption and nitrogen adsorption isotherms. The values of total specific surface area were the highest in Cryosols on mud boils, lower on cell forms, and the lowest on sorted circles. Such tendency was observed for the results obtained by both the water vapour and nitrogen adsorption. The differences in the values of specific surface area at two investigated layers were small. High determination coefficients were obtained for relationships between the specific surface areas and contents of clay and silt fraction in Cryosols. No statistically significant correlation between the total carbon amount and the values of specific surface area in Cryosols has been found.

The role of frost boils in the development of cryozems on coastal lowlands of northern Yakutia

The influence of frost boils on the development of cryozems (Turbic Cryosols) in the tundra zone of northern Yakutia is discussed. Mechanisms of the input, redistribution, and transformation of raw organic matter with its accumulation in the deep part of the profile of cryozems are elucidated. As a result, specific organomineral or organic horizons are formed above the permafrost table. The development of cryozems has a cyclic pattern: from the stage of barren frost boil to the stage of mature soil profile. However, this cycle can be interrupted at any stage of overgrowing of the barren surface of frost boil. The rates of overgrowing and the formation of the profile of cryozem, and the 14C age of organic matter accumulated in the organomineral suprapermafrost horizons are estimated.

Diurnal evolution of the temperature sensitivity of CO2 efflux in permafrost soils under control and warm conditions.

Cryosols contain ~33% of the global soil organic carbon. Cryosol warming and permafrost degradation may enhance the CO2 release to the atmosphere through the microbial decomposition. Despite the large carbon pool, the permafrost carbon feedback on the climate remains uncertain. In this study, we aimed at better understanding the diurnal evolution of the temperature sensitivity of CO2 efflux in Cryosols. A Histic Cryosol and a Turbic Cryosol were instrumented in tussock tundra ecosystems near Salluit (Nunavik, Canada). Open top chambers were installed during summer 2011 and the ground temperature, the soil moisture and meteorological variables were recorded hourly while the ecosystem respiration was measured three times per day every second day with opaque and closed dynamic chambers in control and warm stations. Despite warmer conditions, the average CO2 efflux at the control stations at the Histic site (1.29±0.45μmolCO2m-2s-1) was lower than at the Turbic site (2.30±0.74μmolCO2m-2s-1). The increase in CO2 efflux with warming was greater in the Histic Cryosol (~39%) than in the Turbic Cryosol (~16%). Our study showed that the temperature sensitivity of the ecosystem respiration evolved during the day and decreased with the experimental warming. Both sites exhibited diurnal hysteresis loops between CO2 efflux and the soil surface temperature. The width of hysteresis loops increased with the solar radiation and decreased along the growing season. We developed simple linear models that took into account the diurnal evolution of the temperature sensitivity of CO2 efflux and we estimated the seasonal cumulative carbon release to the atmosphere. The calculation using solely diurnal measurements significantly differed from the seasonal carbon release modelled hourly. Our study highlighted that the time of the day when measurements are performed should be taken into account to accurately estimate the seasonal carbon release from tundra ecosystems.

Temperature regimes of northern taiga soils in the isolated permafrost zone of Western Siberia

Soil temperature regimes were studied in three ecosystems of the north of Western Siberia in the zone of isolated permafrost: the forest ecosystem with gleyic loamy sandy podzol (Stagnic Albic Podzol), the flat-topped peat mound ecosystem with humus-impregnated loamy sandy to light loamy peat cryozem (Histic Oxyaquic Turbic Cryosol (Arenic)), and the peat mound (palsa) ecosystem with oligotrophic destructive permafrost-affected peat soil (Cryic Histosol). Annual temperature measurements in the soil profiles demonstrated that these soils function under different temperature regimes: very cold permafrost regime and cold nonpermafrost regime. The following annual temperature characteristics proved to be informative for the studied soils: sums of above-zero temperatures at the depths of 10 and 20 cm, the maximum depth of penetration of temperatures above 10°C, and the number of days with daily soil temperatures above (or below) 0°C at the depth of 20 cm. On the studied territory, the insulating effect of the snow cover in winter was at least two times more pronounced than the insulating effect of the vegetation cover in summer. Cryogenic soils of the studied region are characterized by the high buffering towards changing climatic parameters. This is explained by the presence of the litter and peat horizons with a very low thermal diffusivity and by the presence of permafrost at a relatively shallow depth with temperature gradients preventing penetration of heat to the permafrost table.

Hydrophysical characteristics of selected soils from arctic and temperate zones

Abstract Hydrophysical characteristics of arctic and temperate zones soils were determined. The soils from the temperate zone showed a greater capability of water retention than those from the arctic zone. In both investigated depths (surface and subsurface layers), the highest water content was observed for the Sądecki Regosol, and the lowest one for Turbic Cryosol formed in the cell forms from Spitsbergen at all soil water potentials. The differences between water content for these soils at the same soil water potentials varied between 20 and 25% vol. in the surface layer, and from 19 to 22% vol. in the subsurface, respectively. The lowest differences (2.7-5.0% vol.) in water content were noticed between the Wyspowy Regosol and Turbic Cryosol (Skeletic) derived in the sorted circles. In both depths, higher values of water conductivity were observed for Regosols than for Cryosols at high soil water potentials, from -0.1 till -7 kJ m-3. These differences were especially high at -0.1 kJ m-3 and they were three or four times higher for soils from the temperate zone than from the arctic ones. For lower water potentials, the differences in water conductivity do not exceed one order in the surface layer and two orders in the subsurface.

Soil properties, micromorphology, and mineralogy of Cryosols from sorted and unsorted patterned grounds in the Hornsund area, SW Spitsbergen

Patterned grounds are probably the most interesting features produced by natural processes acting on the Earth's surface. Such features occur mainly in polar areas and in high mountains indicating that the origin of patterned grounds is related to frost action and cryoturbation. In spite of the many studies concerning the mechanism of the formation and the various forms of patterned grounds, very little attention has been paid to the qualitative and quantitative analyses of their mineral composition, and especially the mineralogy of the clay fraction. The analysis of the mineralogy of clay fraction is very important due to the finest particles (especially clay minerals) may play a crucial role in cryoturbation and cryosegregation as the particles are mainly responsible for accumulation of water and rheological properties of the ground. Thus, the main aim of the present study was to verify the hypothesis that the presence of swelling clay minerals in parent material favors the development of sorted patterned grounds. To verify the hypothesis, the physical, chemical, micromorphological, and qualitative and quantitative mineralogical properties of Cryosols from sorted and unsorted patterned grounds in the Hornsund area (SW Spitsbergen) were determined. The obtained results show that Turbic Cryosols from sorted patterned grounds featuring clear frost cracking, frost segregation, and cryoturbation are characterized by a lack of clearly developed soil horizons, loamy texture and low content of soil organic matter. Haplic Cryosols show better developed soil horizonation and contain lower amounts of the silt and clay fractions, higher content of the sand fraction and soil organic matter in comparison with Turbic Cryosols exhibiting strong cryoturbation. Micromorphological analysis of Turbic Cryosols indicates frost action manifested by a vesicular microstructure; round, oval, and deformed (mammillated) vesicles as dominant voids; vertically-oriented rock fragments; and silt and silt–clay cappings occurring on rock fragments. In addition, the occurrence of Fe–Mn nodules showing a sharp boundary indicates mixing of soil material. Micromorphology of the studied Turbic Cryosols indicates that cryoturbation prevails over cryosegregation. The soil material of the studied Cryosols is composed mainly of quartz, K-feldspar, plagioclase, dioctahedral mica (muscovite and/or illite), biotite, augite, hornblende, garnet, chlorite, swelling clays (smectite, vermiculite), goethite, and in some cases also calcite and traces of kaolinite. Majority of the minerals are most likely primary minerals inherited from parent material due to weak chemical weathering in the severe Arctic climate conditions and relatively young soils. However, weak chemical weathering of biotite and formation of vermiculite and mixed layered clay minerals also take place. Quantitative mineralogical analysis shows that besides texture and moisture, the mineral composition of soil material may also play some role in the susceptibility to cryoturbation and the formation of sorted and unsorted patterned grounds. However, the small differences in mineral content between the studied Turbic Cryosols and Haplic Cryosols indicate that the mineral composition of parent material is not a crucial characteristic responsible for the formation of sorted patterned grounds.

Landscape evolution in the periglacial zone of Eastern Europe since MIS5: Proxies from paleosols and sediments of the Cheremoshnik key site (Upper Volga, Russia)

A variety of studies of the re-examined (new exposure) Late Pleistocene key section Cheremoshnik (East European plain, middle of the Volga Basin of Yaroslavl) was conducted on a new methodological level using modern methods. For the first time, a series of paleosols (MIS5–MIS1) from the section offering significant information in regard to chronostratigraphy and landscape evolution have been studied in detail and dated. An excavation ∼7 m deep reveals a soil-sediment stratum which formed over the course of ∼115 ka in an accumulative beam-like terrace and consists of five lithological layers and six pedostratigraphical units.The base of the section was determined to be an Early Mikulino peat-dark humus paleosol which marked incipient subaerial pedogenesis on the Moscow (Riss II) moraine and was covered with a thickness of gyttja with a peat horizon (Histosol) which had formed 114–115 ka and was reliably dated using uranium–thorium dating. The following paleosols were successfully identified within the series of weak stone gullied-channel sediments within the Valdai (Wűrm) thickness (from bottom to top): (1) Bryansk paleosol (MIS3) – Gleysol – with three pedogenesis rhythms; (2) Trubchevskaya paleоsol – Gleyic Turbic Cryosol (MIS2) and (3) pedosediment formed at the end of the Bӧlling interstadial (MIS2). Terminal Pleistocene formations are marked with a gravelly stratum on the section's surface formed during the Preboreal period. Recent Regosol formed on loess-like loam deposits was identified at the top of the whole soil-sediment stratum. The 14C age of the paleosol humus varied between 27,500 and 11,400 cal. BP. The paleosols represent the northernmost occurrence of MIS5–MIS2 fossil soil in Europe, dominated by features of gleyzation, cryogenic aggregation, cracking, and humus and peat formation.Pollen analysis results allowed estimation of changes in vegetation cover, climatic conditions and the age of deposit sedimentation for the period from the Moskow Late Glacial to the Valdai Late Glacial and early Holocene times. Successive stages in the development of vegetation, high contents of alder and hazel pollen and the climax and distinct appearance of broadleaf trees relate the formation of biogenic sediments (LPAZ 2–6) in the Cheremoshnik section to the Mikulino Interglacial. Valdai (MIS4–MIS2) glacial sediment is absent within the investigated area.