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Remote sensing methods make it possible to evaluate the reaction of the cryolithozone and tundra landscapes in hard-to-reach Arctic areas based on the indicators of modern climate changes. In 2016–2019, numerous organic frost boils were discovered on the peatland surfaces of drained lakes in the southern tundra of the Pur-Taz interfluve in the northern part of West Siberia and studied. It is established that the formation of frost boils caused by organic mass injections occurs in the summertime and that they indicate local deepening of seasonal thawing. Frost boils emerging at peatlands in summertime was identified after analysis of UAV survey in 2019. Local deepening of seasonal thaw layer on polygonal peatlands is evidence of permafrost reaction to global warming.

In 2016-2017, we have detected numerous organic frost boils on the surface of khasyrey peat plateau in the southern tundra part of Pur-Taz interfluve (the north of West Siberia). They are related to the microrelief depressions in polygons and to the swales between tussocks. Cross-sections, cryogenic structure, properties of peat in active layer (moisture, density, heaving, chemical composition) and peat distribution within the khasyreys were studied. In the active layer, we distinguished soil and vegetation cover, upper and middle solid layers of weakly decomposed peat, lower layer of a well decomposed peat. Under the microrelief depressions, the top of permafrost is lowered, thickness and moisture of decomposed peat is increased due to the recent thawing in comparison to the elevated parts of polygons. In the cross-sections of seasonally thawing peat, we determined injections of organic matter from the lower layer of peat to the surface. We propose the mechanism of organic frost boils formation in peat plateau due to the injections during the summer seasons of 2016-2018 against the increase of a thaw depth without freezing. During the observation period, the amount of frost boils on polygonal peat plateau was found to increase.

China’s highway construction has moved from “construction-oriented” to the development stage of “equal attention to construction and maintenance”. The infrastructure represented by urban expressways, under heavy and complex traffic loads, is prone to a variety of diseases that take place in the middle and lower layers of pavement such as “frost boils” and “voids”, which cannot be repaired ideally with the help of conventional detection and treatment techniques. In order to solve the above problems, this paper adopts nondestructive testing plans such as ground penetrating radar and falling weight deflectometer to conduct multidimensional rapid detection of the road surface to obtain the image information and mechanical data of the road structure. Based on the improved calculation method, the pavement disease area, depth and type can be effectively judged. Combined with the observation of water level, the polymer grouting reinforcement plan is designed to eliminate the problems in the middle and lower layers of the road surface. It can effectively reduce the incidence of diseases in the upper layer of the sidewalk, and significantly improve the efficiency and service level of the sidewalk.

International audience; Sediment mobilisation occurring at depth and ultimately manifesting at the surface, is a process which may have operated on Mars. However, the propagation behaviour of this mixture of water and sediments (hereafter simply referred to as mud) over the martian surface, remains uncertain. Although most of the martian surface is below freezing today, locally warmer surface temperatures do occur, and our current knowledge suggests that similar conditions prevailed in the recent past. Here, we present the results of experiments performed inside a low pressure chamber to investigate mud propagation over a warm (~295 K) unconsolidated sand surface under martian atmospheric pressure conditions (~7 mbar). Results show that the mud boils while flowing over the warm surface. The gas released during this process can displace the underlying sand particles and hence erode part of the substrate. This "entrenched" flow can act as a platform for further mud propagation over the surface. The escaping gas causes intermittent levitation of the mud resulting in enhanced flow rates. The mud flow morphologies produced by these phenomena differ from those produced when mud flows over a frozen martian surface as well as from their terrestrial counterparts. The intense boiling removes the latent heat both from the mud and the subsurface, meaning that the mud flow would eventually start to freeze and hence changing again the way it propagates. The diverse morphology expressed by our experimental mudflows implies that caution should be exercised when interpreting flow features on the surface of Mars and other celestial bodies.

Water 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.

Frost-patterned grounds, such as mostly barren frost boils surrounded by denser vegetation, are typical habitat mosaics in tundra. Plant and microbial processes in these habitats may be susceptible ...

Frost heave is a well-known phenomenon in cold regions. It may happen in the wet clayey ground during winter in seasonally frozen regions and during autumn to winter in active layers in permafrost regions. The railway track upheaval, which happens in cold regions, is generally understood as due to frost heaving in subgrade layers. However, it has been confirmed that the upheaval due to frost heaving sometimes happens in the ballast layers. This understanding has been acquired by observing active railway tracks in northern Japan. Samples have been collected from ballast and subgrade layers and have been examined their frost heave susceptibilities along with mineral compositions with X-ray diffraction analysis. The results confirmed that fine materials in the ballast layers consist of clayey minerals and crushed rock-forming minerals of ballast. Those fine minerals have confirmed to be frost heave susceptible with frost heave tests. A series of frost heave tests has conducted using crushed rock and fine material, i.e. Kaolinite, mixture and confirmed that the mixtures frost heave. The frost heave susceptibility of the mixture is almost proportional to the saturation ratio of the fine materials in its voids, even if the voids of the crushed rock are not saturated with fine materials. This has been understood that initially crushed rocks support the overburden and the fine materials in voids does not have to support overburden. Then the high heave ratio is expected in the fine materials until the voids are filled with fine materials and ice lenses. After the voids are filled with the fine materials and ice lenses, segregating ice lens starts to push up the overburden, 1.e. ballast layer, and cause macroscopic upheaval due to frost heaving.

Landscape heterogeneity impacts community assembly in animals and plants, but it is not clear if this ecological concept extends to microbes. To examine this question, we chose to investigate polar soil environments from the Antarctic and Arctic, where microbes often form the major component of biomass. We examined soil environments that ranged in connectivity from relatively well-connected slopes to patchy, fragmented landforms that comprised isolated frost boils. We found landscape connectedness to have a significant correlation with microbial community structure and connectivity, as measured by co-occurrence networks. Soils from within fragmented landforms appeared to exhibit less local environmental heterogeneity, harboured more similar communities, but fewer biological associations than connected landforms. This effect was observed at both poles, despite the geographical distances and ecological differences between them. We suggest that microbial communities inhabiting well-connected landscape elements respond consistently to regional-scale gradients in biotic and edaphic factors. Conversely, the repeated freeze thaw cycles that characterize fragmented landscapes create barriers within the landscape and act to homogenize the soil environment within individual frost boils and consequently the microbial communities. We propose that lower microbial connectivity in the fragmented landforms is a function of smaller patch size and continual disturbances following soil mixing.

There are unusual patterns of greenhouse gas (GHG) net production in soil profiles of Arctic polar deserts. These deserts include frost boils that are symptomatic of permafrost-associated soils. Some frost boils contain diapirs, intrusions of recently thawed, carbon- and water-rich fine material pushed upward into the overlying active layer. Here we identified diapir-associated frost boils in an Arctic polar desert that we had previously found to have highly variable patterns of GHG net production, and compared patterns of GHG net production in soil profiles between diapir and non-diapir frost boils. In addition, we tested the repeatability of soil gas probes measurements and if estimates of diffusivity based on bulk density were accurate. Probes were installed in frost boils identified as including or not including diapirs, and measurements were conducted over several days to evaluate net GHG production. Soil gas probes deployed for longer than approximately 3 d showed loss of signal, and the injection of an inert tracer, SF₆, validated our estimates of soil diffusivity based on bulk density. Diapir-associated frost boils showed reduced soil respiration compared with non-diapir frost boils, despite these diapir-associated frost boils having increased soil organic matter content. Thus, diapir intrusions in frost boils of the Arctic polar desert simultaneously store greater amounts of organic C and reduce soil respiration compared with non-diapir frost boils. Differences in soil organic matter quality and/or its interaction with soil texture may be an important control for carbon storage in Arctic soils.

Moisture is critical for plant success in polar deserts but not by the obvious pathway of reduced water stress. We hypothesized that an indirect, nutrient-linked, pathway resulting from unique water/frozen soil interactions in polar deserts creates nutrient-rich patches critical for plant growth. These nutrient-rich patches (diapirs) form deep in High Arctic polar deserts soils from water accumulating at the permafrost freezing front and ultimately rising into the upper soil horizons through cryoturbated convective landforms (frost boils). To determine if diapirs provide an enhanced source of plant-available N for Salix arctica (Arctic willow), we characterized soil, root, stem, and leaf 15 N natural abundance across 24 diapir and non-diapir frost boils in a High Arctic granitic semi-desert. When diapir horizons were available, S. arctica increased its subsurface (i.e., diapir) N uptake and plant root biomass doubled within diapir. Plant uptake of enriched 15 N injected into organic rich soil patches was 2.5-fold greater in diapir than in non-diapir frost boils. S. arctica percent cover was often higher (7.3 ± 1.0 [mean ± SE]) on diapiric frost boils, compared to frost boils without diapirs (4.4 ± 0.7), potentially reflecting the additional 20% nitrogen available in the subsurface of diapiric frost boils. Selective N acquisition from diapirs is a mechanism by which soil moisture indirectly enhances plant growth. Our work suggests that diapirs may be one mechanism contributing to Arctic greening by shrub expansion.

Beaver Slide is near 177.8 km (110.5 mi) on the Dalton Highway and the road gradient is approximately 11%, built on a hill side. Each year, soft spots, also commonly named as frost boils, were observed starting from late April and lasting for the entire summer. The frost boils have resulted in an extremely unsafe driving condition and frequent accident occurrences. Conventional repair methods cannot effectively solve this issue. A newly developed geotextile, which has high specific surface area, was installed in the selected test section to mitigate the frost-boil issue in August 2010. This type of geotextile can provide high wettability and relatively high suction (capillary force), consequently be able to laterally transport water (a high-directional transmissivity) under unsaturated conditions. Test results over the initial 2 years had proved the effectiveness of the geotextile to alleviate frost heave and the subsequent thaw-weakening issue. However, there were still some concerns regarding it...

Cryoturbation in high-latitude soils is crucial for the long-term cycling of elements, but the rates of soil motion are poorly constrained. Here, we test whether the rate of frost creep, soil erosion and vertical soil mixing in frost boils can be estimated using short-lived radionuclides (Cs-137 and Pb-210). We find a small-scale variation in Cs-137 and Pb-210 inventories in the lower levels of the eroding regions of frost boils in comparison to the expected depositional sites; hence, the distribution of the radionuclides appears to reflect a lateral transport of atmospheric fallout from the centre of the boil (inner domain) towards the surrounding soil (outer domain). C-14 dating of the soil indicates that fallout of Cs-137 was mobile in the soil and that Pb-210 moved with the soil matrix. A soil creep model and a surface soil erosion model are derived and applied to the lateral and vertical distributions of Pb-210 in the frost boil. Both models predict the expected trajectories of soil motion and provide rates of creep, erosion and mixing at a mm yr(-1) to cm yr(-1) scale. The distribution of Pb-210 provides new insights about the processes and rates of soil mass movement in frost boils, if sound mass-balance models are applied. Copyright (C) 2014 John Wiley & Sons, Ltd.

Beaver Slide is on the Dalton Highway near 177.8 km (110.5 mi), and it is downhill when heading north. The road gradient is approximately 11% and the road prism is on a side hill. Each year, there are soft spots that usually appear in late April and remain all summer, which are also called “frost boils” by engineers at the Alaska Department of Transportation and Public Facilities (AKDOT&PF). The frost boils have resulted in extremely unsafe driving conditions and frequent accidents. Past repair efforts indicate conventional road construction methods do not work. A new type of geosynthetic wicking fabric has been recently developed that has a high specific surface area (consequently high wettability and high capillary action) and high directional permittivity. Preliminary laboratory tests indicate it has great promise as a cost-effective means to solve the frost heave-related problems on northern road systems. This study verifies the effectiveness of the wicking fabric to mitigate frost boils in Al...

Expansive Soil is a kind of high plastic clay. Because it has Strong hydrophilic mineral composition, its engineering prosperities embodies that its shape contracts under dehydrating, Inflation and softening under the influence of water and the strength attenuates. This is very difficult to construct in the region of expansive soil. In the region of seasonal frozen, as capillary water rising height is larger; it is prone to phenomenon of frost boil or thawing settlement. It has important meaning to improve hydrophilic and physical and mechanical properties of expansive soil for Slope stability of embankment and cutting of highway engineering and reducing the cost of investment. The paper discusses the engineering properties of expansive soil in Detail; expound some main methods of improved expansive soil at home and abroad and compare and analysis the mechanism and characteristics of the corresponding methods. The paper introduces preliminary testing methods of Expansive soil performance and prospects improved in the future.

A b s t r a c t. The water retention characteristics of the arctic zone soils ((TurbicCryosol (Skeletic), TurbicCryosols (Siltic, Skeletic) and BrunicTurbicCryosol (Arenic)) derived in different micro-relief forms were determined. Water retention curves were similar in their course for the mud boils, cell forms, and sorted circles ie for TurbicCryosols. For these forms, the mud boils showed the highest water retention ability, whereas the sorted circles – the lowest one. Water retention curves for the tundra polygons (Brunic TurbicCryosol, Arenic) were substantially different from these mentioned above. The tundra polygons were characterized by the lowest bulk density of 1.26 g cm -3 , whereas the sorted circles (TurbicCryosol, Skeletic) – the highest: 1.88 g cm -3 . Total porosity was the highest for the tundra polygons (52.4 and 55.5%) and the lowest – for the sorted circles (28.8 and 26.2%). Pore size distribution of the investigated soils showed that independently of depths, the highest content of large and medium pores was noticed for the tundra polygons ie 21.2-24.2 and 19.9-18.7%, respectively. The lowest content of large pores was observed for the cell forms (6.4-5.9%) whereas the mud boils exhibited the lowest amount of medium sized pores (12.2-10.4%) (both TurbicCryosols Siltic, Skeletic). The highest content of small pores was detected in the mud boils – 20.4 and 19.0%. K e y w o r d s: soils, arctic zone, water retention, pore size distribution

In order to study the features of permafrost in Daxinganling, based on t he methods of field investigation and borehole drilling, as w ell as theoretic analysis and the effects of frozen soil geological conditions, topography features, frozen soil type and permafrost classification the freeze-thaw depth(m),main physical indicators of the Frost soil, natural water content, plastic limit Liquid limit index were analysis .the thaw settlement and frost heave were studied in this paper.

Frost boiling and frost heave are the main factors that cause road damage in cold regions. A new kind of embankment structure, which consists of geotextile, crushed-rock layer and geomembrane, was designed and investigated both in the laboratory and at the field of Budongquan located at Qinghai–Tibet Plateau. Comparison tests were conducted at the same time. The key of the new structure is the porous crushed-rock layer which has smaller thermal conductivity with function of drainage and blocking of moisture migration induced by freezing. Both the laboratory and field research results show that the frost penetration and thawing depths of the new structural embankment are much smaller than those of the coarse-grained soil embankment. Also, the new embankment structure has lower water content in the upper layer and smaller frost heave and thawing settlement than the latter does. In addition, it has good drainage effect. Water coming from the road surface can be drained away from the embankment through the porous crushed-rock layer. All these states that the new structure consisting of the porous crushed-rock layer is superior in frost damage mitigation to the normal structure used in cold regions.

Non-sorted circles (NSCs), also known as frost boils, are common soil frost features that create a small-scale mosaic of vegetation zones in periglacial landscapes. The causes of variation in plant ...

Extensive fields of vegetated, dome-shaped earth hummocks 5–35 cm high and typically 80–200 cm in diameter occur on slopes of up to 15° at elevations of 320–440 m asl on Dartmoor, SW England, but are limited to terrain underlain by metasedimentary rocks and dolerite, and absent from granite areas. Hummocks occur within archaeological sites, implying formation within the last ~ 3000 years and ruling out development over permafrost. The hummocks are composed of frost-susceptible silty soil (modal grain size 10–100 µm) with occasional clasts, but exhibit no evidence for cryoturbation or diapirism. Hummock size and spacing are fairly consistent at particular sites but vary between sites. Hummock age, distribution and characteristics are incompatible with non-frost action origins and most proposed frost action origins (cryostatic pressure, soil circulation, permafrost aggradation, soil injection), but regular spacing and granulometry favour initiation by differential frost heave under conditions of periodic shallow (0.2–0.4 m) seasonal ground freezing. We suggest that hummock growth may reflect migration of silt in advance of inclined freezing planes until equilibrium is achieved with soil loss down hummock sides. Our results confirm that hummock formation by frost action occurs on silty soils in humid cool temperate climates with only limited seasonal frost penetration. Copyright © 2012 John Wiley & Sons, Ltd.

A new instrument for freezing-thawing test was developed by Cold and Arid Regions Environmental and engineering research institute (CAREERI), Chinese academy of sciences. By using this device, silty clay of different water content and dry density were frozen under different conditions of temperature gradients in seasonally frost soil regions, By doing so,the regularity of frost heave amount, water content and dry density in seasonally frost soil regions were illuminated. The test results show that the final frost heave amount enhances with the increase of the water content and dry density. The results may provide some technical and theoretical references for the application of artificial ground freezing in the seasonally frost soilregions.

In a pilot study, we examined whether frost boils grossly mask the effect of site by comparing physical, chemical and microbial soil properties between the middle and edge of frost boils on remote and understudied Browning Peninsula, Antarctica. In addition, we determined the degree to which soil microbial community structure can be attributed to frost boil physical and chemical soil properties. Principle components (PCs) of physical and chemical soil properties and of microbial soil properties were compared between the middle and edge of frost boils and between frost boil replicates. Despite higher soil moisture, % C, % S and % N, pH, total DNA, 16S copy number, total phospholipid fatty acids, bacteria, fungi, proteobacteria, anaerobes, gram-positive bacteria and eukaryotes at frost boil edges, PCs were not significantly different between edge and middle positions. Physical and chemical soil properties between frost boil replicates differed significantly, but not microbial communities. In non-metric multidimensional scaling (NMS) ordinations, soil microbial community structure was affected by differences in frost boil replicates and some frost boil replicates were well separated. Therefore, site factors may play a critical role in determining the soil characteristics of frost boils. It remains to be seen whether stronger gradients in physical, chemical and microbial soil properties will develop across frost boils with continued warming of Antarctic soils. Frost boils may have subtle effects and require consideration in long-term sampling design for understanding the effects of climate change.

The active layer is the zone above permafrost that experiences seasonal freeze and thaw. Active-layer thickness varies annually in response to air and surface temperature, and generally decreases poleward. Substantially less is known about thaw variability across small lateral distances in response to topography, parent material, vegetation, and subsurface hydrology. A graduated steel rod was used to measure the 1998 end-of-season thaw depth across several transects. A balanced hierarchical sampling design was used to estimate the contribution to total variance in active-layer depth at separating distances of 1, 3, 9, 27, and 100 meters. A second sampling scheme was used to examine variation at shorter distances of 0.3 and 0.1 meter. This seven-stage sample design was applied to two sites in the Arctic Foothills physiographic province, and four sites on the Arctic Coastal Plain province in northern Alaska. The spatial variability for each site was determined using ANOVA and variogram methods to compare intersite and inter-province variation. Spatial variation in thaw depth was different in the Foothills and Coastal Plain sites. A greater percentage of the total variance occurs at short lag distances (0–3 meters) at the Foothills sites, presumably reflecting the influence of frost boils and tussock vegetation on ground heat flow. In contrast, thaw variation at the Coastal Plain sites occurs at distances exceeding 10 meters, and is attributed to the influence of well-developed networks of ice-wedge polygons and the presence of drained thaw-lake basins. This information was used to determine an ongoing sampling scheme for each site and to assess the suitability of each method of analysis.

Arctic treeline positions are of fundamental importance to the function of high latitude landscapes, as regulators of surface energy exchange and carbon cycling. Most studies aimed at explaining current and predicting future treeline positions have examined growth trends in mature treeline trees, but treeline advance requires seed production, germination, seedling establishment, and recruitment of new trees beyond the treeline and these processes may not be well correlated with growth of mature trees. Tussock tundra is a widespread, microtopographically complex vegetation type, covering vast areas of northern Alaska and Siberia. We examined a site where the white spruce (Picea glauca) treeline has recently advanced into tussock tundra and asked if white spruce seedlings (~36-cm tall) occurred in tussocks, inter-tussocks, and frost boils disproportionate to the abundance of these habitats in the treeline ecotone. We found that seedlings disproportionately occurred in tussocks and frost boils. Seedlings found in tussocks and frost boils also showed greater branch growth than those in inter-tussocks. Tussocks and frost boils had higher soil temperatures than inter-tussocks. Tussocks had higher N, P, and K availability, whereas frost boils had greater secondary and micronutrient availability. The disproportionate occurrence of seedlings in tussocks and frost boils can likely be explained by the combination of warmer soils and greater nutrient availability. It is also possible that low competition for primary nutrients contributes to the success of seedlings in frost boils. Results of the study highlight the importance of biotic and abiotic facilitation as mediators of treeline advance in a changing Arctic.

Through changing soil thermal regimes, soil moisture and affecting weathering and erosion processes plants can have an important effect on the physical properties and structure of soils. Such physi...

This paper reviews frost-weathering studies in the last five years and proposes key questions to be answered. New techniques have enabled us to monitor moisture contents and crack movements in near-surface hard jointed bedrock and to evaluate seasonal rockfall activity in high mountains. Field monitoring has highlighted the roles of diurnal and annual frost cycles in controlling the timing and magnitude of frost weathering. In the laboratory, bidirectional freezing in soft, porous rocks has produced fractures containing segregated ice layers near the permafrost table, which imply the development of ice-filled fractures in permafrost bedrock over long time-scales. This finding, combined with numerical modelling of the thermal regime in permafrost rock slopes, contributes to the prediction of large-scale rockfalls and rock avalanches triggered by permafrost degradation. Future studies should also focus on explosive shattering, frost weathering of hard-intact rocks, field monitoring of ice segregation and bedrock heave, and the role of frost weathering in landscape evolution.

Three-dimensional ground-penetrating radar (3D GPR) was used to investigate the subsurface structure of ice-wedge polygons and other features of the frozen active layer and near-surface permafrost near Barrow, Alaska. Surveys were conducted at three sites located on landscapes of different geomorphic age. At each site, sediment cores were collected and characterised to aid interpretation of GPR data. At two sites, 3D GPR was able to delineate subsurface ice-wedge networks with high fidelity. Three-dimensional GPR data also revealed a fundamental difference in ice-wedge morphology between these two sites that is consistent with differences in landscape age. At a third site, the combination of two-dimensional and 3D GPR revealed the location of an active frost boil with ataxitic cryostructure. When supplemented by analysis of soil cores, 3D GPR offers considerable potential for imaging, interpreting and 3D mapping of near-surface soil and ice structures in permafrost environments. Copyright © 2007 John Wiley & Sons, Ltd.

This study examined the amount of soil organic carbon (SOC) incorporated by cryoturbation into the active layer and near-surface permafrost of Turbels from northern Alaska. An analysis of 21 pedons revealed that an average of 55% of the SOC density of the active layer and near-surface permafrost could be attributed to redistribution from cryoturbation. Cryoturbation occurs most strongly under conditions of poor drainage, where the parent materials are enriched in silt, and where frost boils are present. Based on published radiocarbon dates of buried SOC, cryoturbation was particularly important during periods of the mid-Holocene when the arctic underwent warming. These results suggest that continued warming of the arctic could accelerate cryoturbation and enable the soil to store more SOC than at present, thereby mitigating some of the loss of CO 2 to the atmosphere from increased soil respiration.

Our aim is to measure and explain the seasonal changes in soil ice content in the frost boils of Galbraith Lake, Alaska. Instruments were installed in a frost boil to monitor the ground surface position and soil state over a period of 4 years. By comparing the subsidence and thaw rates, we calculate the soil ice content as a function of depth. Measured soil temperatures, liquid water contents and bulk apparent thermal conductivities are used to estimate latent heat production and release in the soil. The frost boil heaves during freezing and settles during thaw while the surrounding tundra heaves negligibly, but subsides measurably. Despite large changes in freezing rates from year to year, total heave and its distribution across the frost boil are similar between years. Winter air temperature and snow depth influence the freezing rate and ice distribution as a function of depth, but not the overall heave. This suggests that heave is controlled by water availability rather than the rate of heat removal from the soil. Areal ground subsidence rates between 2 and 5 cm/yr are due to the disappearance of ice at the base of the active layer, raising the possibility of ongoing thermokarst expansion around Galbraith Lake.

Frost heave, frost and snow depths on two earth hummocks (pounus) were monitored from 1992 to 2002 in Finnish Lapland. Frost heave was measured with motometers, frost depth with Gandahl's frost tube containing methylene blue, and snow depth with frost tubes above the ground surface. The annual range of frost heave was from 1 mm to 94 mm. The mean annual frost heave on a peat pounu was up to twice that on a mineral-cored pounu. Frost heave values on the pounus did not differ much from those from the surrounding mire. During the early summer, slow thawing of frost keeps the surface of pounus higher than the surrounding mire surface and this supports the formation of earth hummocks.

This study examines the carbon and nitrogen stocks of soils and vegetation in different frost-boil tundra microsites (rims, troughs and bare soil patches) and aims at elucidating differences in controls of organic matter turnover. Troughs, the wettest microsite, stored the greatest part of soil C and N (23.9 and 1.7 kg m −2 , respectively), while drier rims held only 50% and bare soil patches only about 17% of the C and N found in troughs. Both C and N mineralization rates were higher in rims compared to troughs, suggesting a higher turnover of organic matter in rims. On an areal basis N was predominantly mineralized in mineral horizons, while C mineralization was more or less equally distributed between organic and mineral horizons. Thus, atmospheric warming, which has a stronger effect on the upper soil layers, may increase C mineralization to a higher extent than N mineralization (mainly located in lower soil layers). This suggests that frost-boil tundra ecosystems may be (at least in the short-term) sources of CO 2 to the atmosphere. Furthermore, the combined results of gross N mineralization and net N mineralization measurements showed a higher microbial sink strength for N in rims compared to troughs, suggesting that decomposition of organic material in rims is controlled mainly by N availability, while the main factor constraining decomposition in troughs may be unfavourable hydrothermal conditions. This may lead to differential responses of frost-boil tundra microsites to changing climatic conditions.

Frost boils in northern Alaska vary from large, 2–3-m diameter, barren non-sorted circles to completely vegetated hummocks. Summer warmth increases southwards from the coast. Average thaw-layer thickness shows the opposite trend. Frost heave shows no trend along the climate gradient but is affected by soil texture. Heave is greatest on frost boils with fine-grained sediments. Biomass increases from 183 g m � 2 at the coast to 813 g m � 2 in the Arctic Foothills. An aggrading permafrost table is evident in most of the frost-boil soil profiles, indicating that, over time, accumulation of plant biomass leads to reduced thaw-layer thickness. A conceptual model suggests how vegetation affects the morphology of patterned ground forms. In the coldest parts of the High Arctic well-developed frost boils do not form and there is little vegetation on frost boils or the inter-boil areas. In the warmest parts of the Low Arctic, vegetation is usually sufficient to stabilize the frost boil soils. Frost boils play an important role in Arctic ecosystems functions, including the flux of trace gases to the atmosphere, flux of water and nutrients to streams, and the recycling of important nutrients to wildlife populations. Copyright # 2004 John Wiley & Sons, Ltd.

Sediment transport in the scoria areas of Marion Island is primarily the result of needle-ice-induced frost creep associated with diurnal soil frost cycles. Clasts move most rapidly in fine textured areas (532 mm a−1; SD 382), more slowly in stony areas (161 mm a−1; SD 179), and most slowly in blocky areas (26 mm a−1; SD 23). Movement rates increase with increasing frost susceptibility of sediments, slope angle and altitude. The heave of dowels indicates that frost heave is active in all the scoria areas examined. The depth of effective frost heave increases with increasing altitude, with frost heave being restricted to the upper 100 mm of the soil in low altitude areas (

This paper presents multi-year measurements of solifluction, frost heave and the concurrent thermal and hydrological regimes at two solifluction lobes with seasonal frost in the eastern Alps, Austria. The monitoring system included a new solifluction meter and time-domain-reflectometry (TDR) probes to measure the unfrozen water content of the soil. Three phases of ground thermal and hydrological conditions were identified, each with distinct consequences for soil movements. Rapid frost heave occurred during initial ground freezing in early winter. Freezing intensity and maximum frost penetration are strongly influenced by snow drifting in that period. Another period of marked heaving during spring snowmelt is attributed to meltwater infiltration into the frozen ground. Solifluction commenced at high water contents with the beginning of thaw settlement and was enhanced by daily fluctuations of snowmelt and lateral influx of meltwater. Slow movements continued, or even started, after complete thawing of the ground as long as lateral runoff from snow patches upslope elevated soil water contents. Copyright © 2003 John Wiley & Sons, Ltd.

The genesis of some types of patterned ground, including hummocks, frost boils and sorted stone circles, has been attributed to differential frost heave (DFH). However, a theoretical model that adequately describes DFH has yet to be developed and validated. In this paper, we present a mathematical model for the initiation of DFH, and discuss how variations in physical (i.e. soil/vegetation properties) and environmental (i.e. ground/air temperatures) properties affect its occurrence and length scale. Using the Fowler and Krantz multidimensional frost-heave equations, a linear stability analysis anda quasi-steady-state real-time analysis are performed. Results indicate that the following conditions positively affect the spontaneous initiation of DFH: silty soil, small Young’s modulus, small non-uniform surface heat transfer or cold uniform surface temperatures, and small freezing depths. The initiating mechanism for DFH is multidimensional heat transfer within the freezing soil. Numerical integration of the linear growth rates indicates that expression of surface patterns can become evident on the 10–100 year time-scale.

Differences in the summer insulative value of the zonal vegetation mat affect the depth of thaw along the Arctic bioclimate gradient. Toward the south, taller, denser plant canopies and thicker organic horizons counter the effects of warmer temperatures, so that there is little correspondence between active layer depths and summer air temperature. We examined the interactions between summer warmth, vegetation (biomass, Leaf Area Index, Normalized Difference Vegetation Index), soil (texture and pH), and thaw depths at 17 sites in three bioclimate subzones of the Arctic Slope and Seward Peninsula, Alaska. Total plant biomass in subzones C, D, and E averaged 421 g m � 2 , 503 g m � 2 , and 1178 g m � 2 respectively. Soil organic horizons averaged 4 cm in subzone C, 8 cm in subzone D, and 14 cm in subzone E. The average late-August thaw depths in subzones C, D, and E were 44 cm, 55 cm, and 47 cm respectively. Non-acidic soils in equivalent climates generally have shorter-stature sedge-dominated canopies and many frost boils, and consequently have thicker active layers than acidic soils. The trends reported here are useful for palaeo-ecological reconstructions and predictions of future ecosystem changes in the Low Arctic. Climate change will not lead to uniform thickening of the active layer, and could lead to shallower active layers in some presently dry areas due to paludification. Copyright  2003 John Wiley & Sons, Ltd.

Climate is the most important factor influencing development of cryosols. There is a wide variety of climates for cryosols that ranges from maritime to continental. The mean annual air temperature ranges from +1 °C to −20 °C or colder; the mean annual precipitation ranges from

To determine if canopy gaps offer “safe sites” for recruitment and persistence of arctic-alpine plants, we compared seedling densities in frost boils and closed vegetation, and examined persistence of Diapensia lapponica within frost boils. Seedling density was greater within frost boils, and D. lapponica numbers increased in resurveyed frost boils, suggesting persistence. Lower seed bank size combined with higher seedling numbers confirmed that frost boils represent favorable sites for germination.

The following patterning of the ground surface was observed in the Bellsund region: sorted circles, mud boils, cell forms, solifluction (striped) forms and large polygons (tundra polygons). The soils associated with these forms often have different morphological, granulometric and chemical properties and plant covers. Tundra polygons and surfaces without relief are usually accompanied by relatively well developed brown soils with a dense plant cover (70–100%). Such forms occur mainly on loamy sands and loams with abundant 1.0–0.1 mm particles. Brown soils are rich in humus which decreases with depth. Typical gley soils usually with a sparse plant cover are associated with cell forms, sorted circles and mud boils. Solifluctional forms are usually accompanied by gley-like soils, rarely by brown-like ones. Gley and gley-like soils occur on sediments rich in fractions

Frost heave, ground temperature and moisture were concurrently monitored on two alpine slopes with thin debris mantles. Electrical sensors connected to data loggers permitted automated monitoring of the three variables. Diurnal frost heave of up to 3 cm frequently took place during spring and autumn. Soil moisture contents are regarded as the primary control on the amount of frost heave, while the intensity of freezing is secondary. Heave was usually greatest just after a major rainstorm that produced high moisture contents in the near-surface soil, and decreased with soil desiccation. Rainstorms often interrupted the desiccation process and reactivated frost heaving. Despite reaching a depth of 1 m or more, seasonal frost penetration caused only small amounts to heave, because the lower part of the seasonally frozen layer was not frost-susceptible. These observations imply that the thin debris mantle and periodic precipitation during periods of freeze-thaw combine to result in the predominance of shallow frost creep, which is typical of soil movements in Japanese high mountains.

Permafrost is formed in soils and rocks where mean annual ground surface temperature is maintained below O'C. For most practical purposes permafrost can be considered as impermeable, and the existence of permafrost will therefore influence runoff and near surface moisture content, which is critical to geomorphological processes such as frost sorting, frost heave, solifluction, debris flows and mass transport by fluvial processes. If permafrost is ice-rich, creep might occur in the permafrost. Rock glaciers are defined as the morphological expression of creep in perennially frozen, supersaturated sediments under the influence of gravity alone (Barsch 1978, Fisch et al. 1978, Haeberii 1978). The existence of permafrost also influences the thermal characteristics of the snow cover (Keller & Gubler 1993). This is important to snow meta- morphism and refreezing of meltwater in an ini- tially cold snowpack will delay the first runoff in early spring. Later in spring when the snow is mostly isothermal at 0°C, lo...

Patterned ground is terrain exhibiting surface patterning, primarily in the form of circles, polygons, irregular networks, or stripes. Sorted patterns are defined by alternating soil and clasts, and nonsorted patterns by microrelief or vegetation. Most patterns form through recurrent ground freezing and thawing and are initiated by differential (laterally nonuniform) frost heave. Small sorted forms are produced by shallow differential frost heave or needle-ice heave. Large sorted patterns are probably initiated by differential frost heave, but may develop through buoyancy-driven soil circulation during thaw. Frost polygons develop through recurrent thermal contraction cracking of permafrost and freezing of meltwater in cracks. Earth hummocks and vegetation-defined nonsorted circles are probably initiated by differential frost heave, though buoyancy-driven soil circulation and other mechanisms may contribute to their subsequent development.

The White Mountains of California have a cold semi-arid climate that has led to the development of large areas of periglacial patterned ground. Rates of activity vary widely, and no present activity has been noted below 3600 m. Three distinct scales of patterned ground—having average diameters of 3–5 m, 0.5–1.0 m, and 0.1–0.5 m—exist together in a nested fashion at a favorable location at 3914 m. Vertical heave, horizontal displacement, and surface rotation were investigated on landforms of each scale, to determine rates of activity and the spatial and temporal variation of heave. No movement was detected in the largest landforms, but frost boils located in the centers of the larger sorted polygons were highly active. Rates of heave increased dramatically at the beginning of the thaw season, approaching 3.6 mm per day. Dowels were heaved an average of 16.8 cm over ten months. Disks used as surface markers demonstrated exceptional rotational and radial displacement over a nine-month period; 29% of the mark...