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2022055927 Chiasson, Alexandre (University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada) and Allard, Michel. Thermal contraction crack polygons in Nunavik (northern Quebec); distribution and development of polygonal patterned ground: Permafrost and Periglacial Processes, 33(3), p. 195-213, illus. incl. 5 tables, sketch map, 71 ref., September 2022.
We evaluated the spatial distribution and morphological variability of thermal contraction crack polygon (TCCP) networks across Nunavik, a 440,000-km2 region of northern Québec that spans the northward transition from discontinuous to continuous permafrost. A population of 4,567 TCCP sites was sampled and analyzed from 80,737 georeferenced high-resolution aerial photographs and 264,504 km2 of ESRI satellite basemaps. For each site, six parameters were inventoried and compiled into a database: (a) network geometric arrangement; (b) intersection angles; (c) number of subdivisions and nested polygons (referred to as generations of development); (d) dominant polygon morphology; (e) surficial geology; and (f) vegetation cover. Statistical analyses of the tabulated data revealed a strong association between Holocene glacial, glacio-fluvial, fluvial, marine, and organic landforms and the different intersections angles in the networks, providing insight into how the processes of thermal contraction cracking function and manifest geomorphically across varied permafrost landscapes. Orthogonal polygons (intersection angle of 90°) dominate on flat terrains where the thermo-mechanical stresses are probably spatially homogeneous. Hexagonal (angles of 120°) and poorly structured polygons tend to form where topography variability probably generates heterogeneous heat flow patterns and thermo-mechanical stresses in the ground, resulting in irregular cracking patterns. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2150
2022055929 Forte, Emanuele (University of Trieste, Department of Mathematics and Geosciences, Trieste, Italy); French, Hugh M.; Raffi, Rossana; Santin, Ilaria and Guglielmin, Mauro. Investigations of polygonal patterned ground in continuous Antarctic permafrost by means of ground penetrating radar and electrical resistivity tomography; some unexpected correlations: Permafrost and Periglacial Processes, 33(3), p. 226-240, illus. incl. sketch maps, 68 ref., September 2022.
The results of a combined geophysical and geomorphological investigation of thermal-contraction-crack polygons near Gondwana station (Germany) in northern Victoria Land (Antarctica) are reported. An area of about 20,000 m2 characterized by random orthogonal polygons was investigated using integrated ground penetrating radar, electrical resistivity tomography, geomorphological surveys, and two trench excavations. The polygons are well developed only at elevations higher than 6-7 m above current sea level on Holocene-age raised beaches. It is concluded that the polygons are composite in nature because the shallow linear depressions that outline the polygons are underlain by fissures that can contain both sandy gravel and foliated ice (i.e., ice wedges) even in the same polygon network and at distances of just a few meters. Unexpectedly, most of the polygons follow the border of the raised beaches and develop in correspondence with stratigraphic layers dipping toward the sea, imaged by ground penetrating radar (GPR) profiles and interpreted as prograding layers toward the present-day shoreline. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2156
2022055928 Jan, Ahmad (Oak Ridge National Laboratory, Climate Change Science Institute and Environmental Sciences Division, Oak Ridge, TN). Modeling the role of lateral surface flow in low-relief polygonal tundra: Permafrost and Periglacial Processes, 33(3), p. 214-225, illus. incl. 2 tables, sketch maps, 91 ref., September 2022.
Ice-wedge polygon troughs play an important role in controlling the hydrology of low-relief polygonal tundra regions. Lateral surface flow is confined to troughs only, but it is often neglected in model projections of permafrost thermal hydrology. Recent field and modeling studies have shown that, after rain events, increases in trough water levels are significantly more than the observed precipitation, highlighting the role of lateral surface flow in the polygonal tundra. Therefore, understanding how trough lateral surface flow can influence polygonal tundra thermal hydrology is important, especially under projected changes in temperatures and rainfall in the Arctic regions. Using an integrated cryohydrology model, this study presents plot-scale end-of-century projections of ice-wedge polygon water budget components and active layer thickness with and without trough lateral surface flow under the Representative Concentration Pathway 8.5 scenario. Trough lateral surface flow is incorporated through a newly developed empirical model, evaluated against field measurements. The numerical scenario that includes trough lateral surface flow simulates discharge (outflow from a polygon) and recharge (rain-induced inflow to a polygon trough from upslope areas), while the scenario that does not include trough lateral surface flow ignores recharge. The results show considerable reduction (about 100-150%) in evapotranspiration and discharge in rainy years in the scenarios ignoring trough lateral surface flow, but less effect on soil water storage, in comparison with the scenario with trough lateral surface flow. In addition, the results demonstrate long-term changes (~10-15 cm increase) in active layer thickness when trough lateral surface flow is modeled. This study highlights the importance of including lateral surface flow processes to better understand the long-term thermal and hydrological changes in low-relief polygonal tundra regions under a changing climate. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2145
2022055934 Jiang Guanli (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Lanzhou, China); Gao Siru; Lewkowicz, Antoni G.; Zhao Hongting; Pang Shouji and Wu Qingbai. Development of a rapid active layer detachment slide in the Fenghuoshan Mountains, Qinghai-Tibet Plateau: Permafrost and Periglacial Processes, 33(3), p. 298-309, illus. incl. 1 table, sketch map, 63 ref., September 2022.
An active layer detachment slide (ALDS) in the interior portion of the Qinghai-Tibet Plateau (QTP) was investigated within 2 days of its formation on September 21, 2018. The ALDS developed on a relatively gentle slope (4.8° to 9°) at an elevation of 4,850 m above sea level (asl) and was about 145 m long and 45 m wide, with a headscarp 2.2-2.5 m high. Analyses of meteorological data and soil temperatures indicated that it was probably triggered by a record thaw depth which intersected a layer with high ice content at the base of the active layer and in the top of the permafrost. Based on the time window, the minimum downslope velocity of the main slide mass was about 20 m/h which is higher than previously reported values. The ALDS ran into the embankment of the Qinghai-Tibet Railway (QTR) but did not damage the railbed. However, extensive rehabilitation of the slope was needed subsequent to the failure to clear the slide mass and as minor headscarp recession and thaw settlement continued on the slope. In this work, we describe this feature and the most likely mechanisms of development. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2151
2022055931 Majdanski, Mariusz (Polish Academy of Sciences, Institute of Geophysics, Warsaw, Poland); Dobinski, Wojciech; Marciniak, Artur; Owoc, Bartosz; Glazer, Michal; Osuch, Marzena and Wawrzyniak, Tomasz. Variations of permafrost under freezing and thawing conditions in the coastal catchment Fuglebekken (Hornsund, Spitsbergen, Svalbard): Permafrost and Periglacial Processes, 33(3), p. 264-276, illus. incl. sketch map, 59 ref., September 2022.
Two seismic field surveys were organized in the Fuglebekken coastal catchment of Hornsund, Spitsbergen, Svalbard, to map frozen and unfrozen ground and assess the spatial and temporal state of the permafrost. Surveys were conducted during maximum thawing in September and maximum freezing in April of the following year. The obtained seismic wavefields were interpreted using three methods: the dispersion of surface waves, seismic refraction, and travel time tomography. The seismic experiments were supported by nearby boreholes with continuous thermal monitoring. In the frozen survey, a gradual increase in ice content of water-filled sediments was found, farther from the coast. In September the shallow sensors in the boreholes validated positive ground temperatures down to 3.0 m depth, with below-zero temperatures at greater depths. However, seismic tomography indicated that the ground was unfrozen down to 30 m. The ground probably remained unfrozen due to intrusion of high-salinity seawater, even though it had been below 0°C. In April, in the area 300 m and farther from the coast, the ground below 3 m depth was frozen, except for a 19-m-deep open talik identified in a borehole at the slope of Fugle Mountain. We attribute the complex spatial extent, form, and condition of permafrost in the Fuglebekken coastal catchment to multiple factors, including variable solar energy, snow and ground cover, thermal and humidity properties of the soil, subsurface water flow, and seawater intrusion. The presented combination of seismic methods provides a new robust and precise approach to assess the spatial variability of permafrost in a coastal environment. The proposed interpretation shows deep percolation of subsurface flow into permafrost and its seasonal unfreezing at a depth of 30 m in both the zone of saltwater intrusion and the slope area. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2147
2022055935 Pruessner, Luisa (ETH Zürich, Laboratory of Hydraulics, Hydrology, and Glaciology, Zurich, Switzerland); Huss, Matthias and Farinotti, Daniel. Temperature evolution and runoff contribution of three rock glaciers in Switzerland under future climate forcing: Permafrost and Periglacial Processes, 33(3), p. 310-322, illus. incl. 3 tables, sketch map, 66 ref., September 2022.
With ongoing climate change water availability in the source regions of alpine streams are at stake. In particular, dry mountain regions which currently rely on glacial meltwater will need to adapt. Since rock glaciers are more resilient to climate change and occur in nearly all high-mountain catchments around the globe with some form of glacierization, it is of interest to investigate their contribution to runoff under different climate scenarios. Three well-monitored rock glacier sites in the Swiss Alps (Murtèl, Ritigraben, and Schafberg) have been investigated under the climate change scenarios corresponding to low, medium and high greenhouse gas emissions to determine how their runoff contribution is affected. By the end of the 21st century, runoff from permafrost melting could account for 5-12% (12.0% for Murtèl, 7.0% for Ritigraben, and 5.0% for Schafberg) of monthly catchment runoff at maximum in an average year, and up to 50% in extreme years. For the low-emission scenario, little change in the runoff contribution from rock glaciers is found, while the medium-emission scenario shows increased variability and a shift in the seasonal runoff peak to earlier in the year. The high-emission scenario indicates a further increase in the variability of the permafrost runoff contribution and also the development of a secondary seasonal peak in autumn, most prominently in the late century. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2149
2022055933 Wang Qingfeng (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Lanzhou, China); Jin Huijun; Wu Qingbai; Zhang Tingjun; Yuan Ziqiang; Li Xiaoying; Ming Jiao; Yang Chengsong; Serban, Raul David and Huang Yadong. The vertical distribution of soil organic carbon and nitrogen in a permafrost-affected wetland on the Qinghai-Tibet Plateau; implications for Holocene development and environmental change: Permafrost and Periglacial Processes, 33(3), p. 286-297, illus. incl. 3 tables, sketch map, 98 ref., September 2022.
Currently, we know little about accumulation of soil carbon and nitrogen in permafrost-affected wetlands on the Qinghai-Tibet Plateau (QTP). In this study, we analyze the vertical distribution of concentrations, stocks, and apparent accumulation rates of soil organic carbon (SOC) and total nitrogen (TN) in a wetland underlain by ice-rich permafrost in the Headwater Area of the Yellow River (HAYR) on the northeastern QTP in the context of Holocene environmental change. SOC and TN stocks at depths of 0-216 cm were 80.0 kg C m-2 and 6.7 kg N m-2, respectively. During the past 7.3 kyr, the general regional climate trend in the HAYR was cooling and drying, as indicated by the decline in chemical weathering in the soil profile. Overall, SOC and TN concentrations increased during this period. Meanwhile, an intense period of SOC and TN accumulation occurred at 1,110-720 yr BP, in contrast to much lower apparent accumulation rates of SOC and TN for the other periods during the past 7.3 kyr. This suggests that the accumulation of SOC and TN in permafrost-affected wetlands was also affected by local environmental factors, such as soil material deposition rate, in addition to climatic controls as exerted mainly by temperature and precipitation. This study may help integrate relevant studies on plateau wetlands into global models and estimates to better simulate and predict interactions between the carbon cycle and climate changes on a global scale. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2146
2022055932 You Yanhui (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Lanzhou, China); Yu Qihao; Wang Xinbin; Guo Lei; Chen Kun and Wu Qingbai. Effects of thermosyphons on the thermal regime and stability of cast-in-place piles in permafrost regions on the Qinghai-Tibet Plateau: Permafrost and Periglacial Processes, 33(3), p. 277-285, illus. incl. sketch map, 25 ref., September 2022.
The thermal effects of cast-in-place piles on the surrounding permafrost frequently induce deformation or failure of piles in permafrost regions. Because piles are directly inserted into the permafrost layer, the thermal disturbance of the piles is more straightforward than that of road embankments to the permafrost. Thermosyphons have proven to be effective in stabilizing the embankments of highways and railways in permafrost regions. However, the effects of thermosyphons on the thermal regime and stability of the cast-in-place piles remain unclear. The foundation soils of most piles in permafrost regions along the Qinghai-Tibet Power Transmission Line were cooled by thermosyphons, and the results of a 7-year-period monitoring of ground temperature and deformation of a pile are presented in this paper. The results showed that the extent of thawed permafrost during the installation of the pile extended more than 5 m away from the pile. Thermosyphons shortened the refreezing time by more than 2 months. Thermosyphons cooled the surrounding permafrost to temperatures below the ambient ground temperature at the end of the cold seasons, and the temperature difference lasted until the end of the warm seasons owing to cold reserves formed in the cold season. The thermosyphons mitigated the thermal effects of the concrete pile owing to their higher thermal conductivity. Thermosyphons also significantly decreased the rate of active layer thickening around the pile compared to that observed in a natural field under a warming climate. Generally, thermosyphons stabilized the piles during the observation period by cooling the permafrost around the pile and producing a greater adfreeze force to counteract the frost heave force and subsequently support the tower. Additional thermosyphons or insulation measures may be necessary to ensure the long-term stability of piles, considering a faster degradation of the ambient permafrost than expected. The results may provide insights into the design and maintenance of cast-in-place piles in warm permafrost regions. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2144
2022055840 Herring, Teddi (University of Ottawa, Department of Geography, Environment and Geomatics, Ottawa, ON, Canada) and Lewkowicz, Antoni G. A systematic evaluation of electrical resistivity tomography for permafrost interface detection using forward modeling: Permafrost and Periglacial Processes, 33(2), p. 134-146, illus. incl. 1 table, 48 ref., June 2022.
The accuracy of electrical resistivity tomography (ERT) as a method for locating frozen-to-unfrozen interfaces in permafrost environments was investigated systematically for simplified scenarios using forward modeling. The impacts of varying the resistivity, thickness, and lateral continuity of the frozen region, altering the thickness of the surface thaw layer, and of differing array types were evaluated in relation to the detection and positioning of frozen-unfrozen interfaces. The results from these simple scenarios show that boundaries between frozen and unfrozen ground are more accurately indicated by maximum gradients rather than a fixed threshold value based on the resistivity at the base of the surface thawed layer. The resistivity of the frozen region plays a significant role in interpreted boundary locations, with high resistivity values causing a decrease in model sensitivity at depth and increased uncertainty in the interpreted base of the frozen zone, particularly in laterally continuous permafrost. Error in the interpreted base of the frozen zone also increases for thicker permafrost bodies, while thaw layer thickness plays a less significant role. In laterally discontinuous permafrost, wider frozen bodies cause the boundary at the base of the frozen region to become less distinct. Array type affected the appearance of the inverted resistivity models and the frozen-unfrozen boundaries located using the threshold method, but boundary locations were comparable among array types when the maximum gradient method was used. This synthetic modeling showed that the boundaries between unfrozen and frozen regions in ERT images should be interpreted with caution, particularly in ice-rich, laterally continuous permafrost where sensitivity at depth is low. We conclude that forward modeling is a useful tool for permafrost investigations, both for assessing the likelihood of achieving ERT survey goals prior to fieldwork, and as an interpretive aid after field data have been acquired. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2141
2022055843 Lantz, Trevor C. (University of Victoria, School of Environmental Studies, Victoria, BC, Canada); Zhang, Yu and Kokelj, Steven V. Impacts of ecological succession and climate warming on permafrost aggradation in drained lake basins of the Tuktoyaktuk coastlands, Northwest Territories, Canada: Permafrost and Periglacial Processes, 33(2), p. 176-192, illus. incl. 2 tables, sketch map, 111 ref., June 2022.
Rapidly increasing air temperatures will alter permafrost conditions across the Arctic, but variation in soils, vegetation, snow conditions, and their effects on ground thermal regime complicate prediction across spatial and temporal scales. Processes that result in the emergence of new surfaces (lake drainage, channel migration, isostatic uplift, etc.) provide an opportunity to assess the factors influencing permafrost aggradation and terrain evolution under a warming climate. In this study we describe ground temperatures, vegetation, and snow and soil conditions at six drained lake basins (DLBs) that have exposed new terrain in the Tuktoyaktuk Coastlands in the last 20-100 years. We also use one-dimensional thermal modeling to assess the impact of ecological succession and future climate scenarios on permafrost conditions in historical and future DLBs. Our field observations show that deep snow pack and shallow organic layers at shrub-dominated DLBs promote increased thaw depth and ground temperatures compared to a sedge-dominated DLB and two ancient DLB reference sites. Modeling of past and future drainages shows that climate warming projected under RCP 8.5 will reduce rates of permafrost aggradation and thickness, and drive top-down thaw that could degrade permafrost in shrub-dominated DLBs by the end of the century. Permafrost at sedge-dominated sites was more resilient to warming under RCP 8.5, with the onset of top-down thaw delayed until about 2080. Together, this indicates that the effects of ecological succession on organic soil development and snow drifting will strongly influence the aggradation and resilience of permafrost in DLBs. Our analysis suggests that DLBs and other emergent landscapes will be the first permafrost-free environments to develop under a warming climate in the continuous permafrost zone. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2143
2022050257 Villani, Maëlle (Université Catholique de Louvain, Earth and Life Institute, Louvain-la-Neuve, Belgium); Mauclet, Elisabeth; Agnan, Yannick; Druel, Arsène; Jasinski, Briana; Taylor, Meghan; Schuur, Edward A. G. and Opfergelt, Sophie. Mineral element recycling in topsoil following permafrost degradation and a vegetation shift in sub-Arctic tundra: Geoderma, 421, Article 115915, illus. incl. 1 table, sketch map, 69 ref., September 1, 2022.
Climate change affects the Arctic and sub-Arctic regions by exposing previously frozen permafrost to thaw, unlocking soil nutrients, changing hydrological processes, and boosting plant growth. As a result, sub-Arctic tundra is subject to a shrub expansion, called "shrubification", at the expense of sedge species. Depending on the intrinsic foliar properties of these plant species, changes in foliar mineral element fluxes with shrubification in the context of permafrost degradation may influence topsoil mineral element composition. Despite the potential implications of changes in topsoil mineral element concentrations for the fate of organic carbon, this remains poorly quantified. Here, we investigate vegetation foliar and topsoil mineral element composition (Si, K, Ca, P, Mn, Zn, Cu, Mo, V) across a natural gradient of permafrost degradation at a typical sub-Arctic tundra at Eight Mile Lake (Alaska, USA). Results show that foliar mineral element concentrations are higher (up to 9 times; Si, K, Mo for all species, and for some species Zn) or lower (up to 2 times; Ca, P, Mn, Cu, V for all species, and for some species Zn) in sedge than in shrub species. As a result, a vegetation shift over ~40 years has resulted in lower topsoil concentrations in Si, K, Zn, and Mo (respectively of 52, 24, 20, and 51%) in highly degraded permafrost sites compared to poorly degraded permafrost sites due to lower foliar fluxes of these elements. For other elements (Ca, P, Mn, Cu, and V), the vegetation shift has not induced a marked change in topsoil concentrations at this current stage of permafrost degradation. A modeled amplified shrubification associated with a further permafrost degradation is expected to increase foliar Ca, P, Mn, Cu, and V fluxes, which will likely change these element concentrations in topsoil. These data can serve as a first estimate to assess the influence of other shifts in vegetation in Arctic and sub-Arctic tundra such as sedge expansion under wetter soil conditions.
DOI: 10.1016/j.geoderma.2022.115915
2022051992 Evans, Sarah G. (Appalachian State University, Department of Geological and Environmental Sciences, Boone, NC); Raberg, Jonathan H.; Crump, Sarah E.; Raynolds, Martha K.; Sugg, Margaret M.; Brodie, Alexander R. and Miller, Gifford H. Control of short-stature vegetation type on shallow ground temperatures in permafrost across the eastern Canadian Arctic: Journal of Geophysical Research: Biogeosciences, 127(7), Article e2022JG006941, illus., 89 ref., July 2022. Part of a special section entitled the Arctic; and AGU joint special collection.
The Arctic has warmed three times the rate of the global average, resulting in extensive thaw of perennially frozen ground known as permafrost. While it is well understood that permafrost thaw will continue and likely accelerate, thaw rates are nonuniform due, in part, to the expansion of Arctic trees and tall shrubs that may increase ground temperatures. However, in permafrost regions with short-stature vegetation (height < 40 cm), our understanding of how ground temperature regimes vary by vegetation type is limited as these sites are generally found in remote high-latitude regions that lack in situ ground temperature measurements. This study aims to overcome this limitation by leveraging in situ shallow ground temperatures, remote sensing observations, and topographic parameters across 22 sites with varying types of short-stature vegetation on Baffin Island, Canada, a remote region underlain by rapidly warming continuous permafrost. Results suggest that the type of short-stature vegetation does not necessarily correspond to a distinct shallow ground temperature regime. Instead, in permafrost regions with short-stature vegetation, factors that control snow duration, such as microtopography, may have a larger effect on evolving ground temperature regimes and thus permafrost vulnerability. These findings suggest that anticipating permafrost thaw in regions of short-stature vegetation may be more nuanced than previously suggested. Abstract Copyright (2022), The Authors.
DOI: 10.1029/2022JG006941
2022051995 Ola, A. (Université Laval, Département de Chimie, Quebec, QC, Canada); Fortier, D.; Coulombe, S.; Comte, J. and Domine, F. The distribution of soil carbon and nitrogen stocks among dominant geomorphological terrain units in Qarlikturvik Valley, Bylot Island, Arctic Canada: Journal of Geophysical Research: Biogeosciences, 127(7), Article e2021JG006750, illus. incl. 3 tables, geol. sketch map, 87 ref., July 2022.
Soils of circumpolar regions store large amounts of carbon (C) and are a crucial part of the global C cycle. Yet, little is known about the distribution of soil C stocks among geomorphological terrain units of glacial valleys in the Arctic. Soil C and nitrogen (N) content for the top 100 cm of the dominant vegetated geomorphological terrain units (i.e., alluvial fans, humid polygons, mesic polygons) at Qarlikturvik Valley, Bylot Island, Canada have been analyzed. Soil C content was greatest in humid low-center ice-wedge polygons (82 kg m-2), followed by mesic flat-center ice-wedge polygons (40 kg m-2), and alluvial fan area (16 kg m-2), due to prevailing geomorphological processes, differences in vegetation and soil characteristics, as well as permafrost processes. Soil N content was greatest in humid polygons (4 kg m-2), followed by mesic polygons (2 kg m-2), and alluvial fan area (1 kg m-2). Vertically, C and N decreased with increasing depth except for a peak in C at depth in humid polygons, a likely result of past changes in vegetation cover. At Qarlikturvik Valley, which has a size of 121.7 km2, alluvial fans store 0.226 Tg organic C and humid and mesic polygons store 1.643 and 0.218 Tg organic C, respectively in the top 100 cm of soil. Findings like these are important to further constrain pan-Arctic soil C and N stock estimates and thus climate models. Abstract Copyright (2022), American Geophysical Union. All Rights Reserved.
DOI: 10.1029/2021JG006750
2022054419 He Ruixia (Chinese Academy of Sciences, State Key Laboratory of Frozen Soils Engineering and Da Xing'anling Observation and Research Station of Frozen-Ground Engineering and Environment, Northwest Institute of Eco-Environment and Resources, Lanzhou, China); Jin Huijun; Luo Dongliang; Huang Yadong; Ma Futing; Li Xiaoying; Wang Hongwei; Li Yan; Jia Ning; Li Xinyu; Jin Xiaoying; Serban, Raul-David; Serban, Mihaela; Zhou Chuanfang; Liang Zhongkai and Sun Yanfeng. Changes in the permafrost environment under dual impacts of climate change and human activities in the Hola Basin, northern Da Xing'anling Mountains, northeast China: Land Degradation & Development, 33(8), p. 1219-1234, illus. incl. strat. col., 2 tables, sketch map, 56 ref., May 15, 2022.
The Hola Basin in the northern Da Xing'anling Mountains in northeast China has been extensively developed for coal mining since the 1980s, resulting in a significantly degrading permafrost environment. However, the changing thermal state of permafrost under the boreal forest remains unclear. Based on ground temperature records from nine monitoring boreholes at three areas (disturbed, backfilled, and undisturbed areas) from 2015 to 2020, the thermal state of permafrost under the dual influences of climate change and human activities were evaluated. It is found that the temperatures at the depth of zero annual amplitude (TZAA) in the disturbed area increased by 0.2-0.5°C during the past 6 years, turning the cold permafrost (TZAA ≤&eq; -1.0°C) into a warm one (-1 ≤&eq; TZAA ≤&eq; 0°C). Additionally, the permafrost table was lowered by 0.8-7.0 m. As a result, subaerial supra-permafrost talik occurred. However, TZAA in the undisturbed areas lowered by 0.03-0.11°C, possibly due to the lagged response of the local climate cooling during 2001-2010. In the meantime, TZAA rose sharply in the disturbed areas, indicating more significant influences of intense human activities on permafrost in comparison with that of climate change. As the permafrost degrades, the boreal permafrost eco-environment has changed dramatically, as revealed by the draining and drying up of the Yueya'hu Lake in the southern Hola Basin. These results help reveal the physical mechanisms, evaluate the rates and amplitudes of environmental changes, and manage the boreal forest environment and resources in a sustainable manner. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ldr.4212
2022055678 Li Chuanhua (Northwest Normal University, College of Geography and Environmental Science, Lanzhou, China); Sun Hao; Liu Lihui; Dou Tianbao; Zhou Min; Li Wangping and Wu Xiaodong. The importance of permafrost in the steady and fast increase in net primary production of the grassland on the Qinghai-Tibet Plateau: Catena (Giessen), 211, Article 105964, illus. incl. 4 tables, geol. sketch maps, 79 ref., April 2022.
Permafrost affects soil water and soil temperature regimes; however, its effects on net primary production (NPP) remain unknown. Here, we examined temporal-spatial changes in grassland NPP during 2000-2018 in permafrost and permafrost-free areas on the Qinghai-Tibetan Plateau using the random forest (RF) and radial basis function artificial neural network (RBF-ANN). Our results indicated that the areas that showed increasing, decreasing, and non-significant trends for NPP accounted for 13.88%, 1.90%, and 84.22% of the permafrost area, respectively. For the permafrost-free areas, these NPP trends accounted for 22.25%, 2.68%, and 75.07% of the permafrost-free area, respectively. The mean NPP in the permafrost regions showed a faster and steadier (1.520 g C/m2/yr, p < 0.05) increase than in non-permafrost regions (1.224 g C/m2/yr, p < 0.05). The Biome-BGC model confirmed that these spatial NPP patterns could be attributed to differences in soil water and soil temperature between permafrost and permafrost-free areas. Both the soil temperature and soil water content in permafrost sites exhibited relatively lower variance than in permafrost-free sites. Although many factors may be attributed to these patterns, our results suggest that there is a possibility that the relatively stable change in permafrost NPP can be explained by the fact that permafrost can regulate soil water and temperature regimes. Therefore, climate warming can increase NPP in cold regions, and permafrost degradation may destabilize the grassland ecosystem, which may cause NPP values to exhibit greater interannual changes in the future.
DOI: 10.1016/j.catena.2021.105964
2022051751 Petrov, Marat I. (Russian Academy of Sciences, Siberian Branch, Melnikov Permafrost Institute, Permafrost Landscapes Laboratory, Yakutsk, Russian Federation); Fedorov, Alexander N.; Konstantinov, Pavel Y. and Argunov, Radomir N. Variability of permafrost and landscape conditions following forest fires in the central Yakutian taiga zone: Land (Basel), 11(4), Article 496, illus. incl. 1 table, sketch map, 39 ref., April 2022.
In the last two decades in Central Yakutia, there has been a significant change in cryogenic landscapes related to climate warming and anthropogenic disturbances. This period is characterized by the activity of forest fires, which significantly impact permafrost landscapes. We observed the dynamics of cryogenic landscapes after a forest fire in 2001 at the Neleger station in Central Yakutia, 35 km northwest of Yakutsk. The observations included ground temperature and active layer thickness monitoring and statements of changes in the soil moisture content of the active layer. Increases in ground temperature, the active layer thickness, and soil moisture content on the burnt site after a forest fire in Neleger station were noted in the first six to seven years after the disturbance. We found that, following forest fires, permafrost progressively restabilizes as forest cover redevelops over time. The results of the studies will become the basis for planning restoration work after forest fires in permafrost landscapes of Central Yakutia.
DOI: 10.3390/land11040496
2022055681 Woronko, B. (University of Warsaw, Faculty of Geology, Warsaw, Poland); Zagorski, Zbigniew and Cyglicki, M. Soil-development differentiation across a glacial-interglacial cycle, Saalian upland, E Poland: Catena (Giessen), 211, Article 105968, illus. incl. 6 tables, geol. sketch map, 105 ref., April 2022.
Three soil profiles at the Koczery site (E Poland), studied through soil and sediment evaluation, reveal a polygenetic development of soils in areas unglaciated during the Weichselian glaciation (MIS 2) period. Pedogenesis had developed on glacial till (till) in period from the Saalian glaciation (MIS 6) to the Holocene (MIS 1). Wide-spectrum analyses demonstrate that the profiles represent a Planosol. Four stages (I-IV) of soil formation were distinguished in the study area. Stage I, comprising of a nutrient- and element-rich material, correlates to the accumulation of Saalian glacial till (MIS 6). Stage II, that took place during the Eemian Interglacial (MIS 5e), corresponds to the initial development of Cambisol as a result of carbonate leaching process. This was followed by the development of a Luvisol through the processes of illuviation of clay minerals and iron components. Stage III bears evidence of intensive frost weathering processes along with a development of sand-wedge cast that occurred under permafrost conditions of Weichselian glaciation (MIS 2). Further, the formation of an aeolian pavement along with erosion and removal of upper portions of the Eemian soil took place. An accumulation of coeval-age coversand led to a restart of the pedological clock, which resulted in the development of cryogenically-altered soils. Stage IV ushered the Holocene (MIS 1) delivering a progressive development of pedogenesis together with plant-succession modifications under temperate-climate conditions. Brunic or luvic horizons are formed within the coversand deposits. Pseudogleyic conditions developed along the lithological discontinuities. Of note, sand-wedge casts (SWCs) occupy specific locations in the profiles that provide the vertical migration of water, base components and iron. Reducing conditions that occurred along the bottom of ice-wedge casts favour the formation of gleyic horizon. SWCs that have been ultimately modified into ice-wedge and acted as sand-wedge-affiliated geochemical corridors (SWGC) for shallow groundwater forming natural tile drains.
DOI: 10.1016/j.catena.2021.105968
2022054380 Bronnikova, M. A. (Russian Academy of Sciences, Institute of Geography, Moscow, Russian Federation); Gerasimova, M. I.; Konoplianikova, Yu. V.; Gurkova, E. A.; Chernousenko, G. I.; Golubtsov, V. A. and Efimov, O. E. Cryoaridic soils as a genetic type in the Russian soil classification system; geography, morphology, diagnostics: Eurasian Soil Science, 55(3), p. 283-298, illus. incl. 2 tables, geol. sketch map, 61 ref., March 2022.
Cryoaridic soils were proposed to be identified as an individual genetic soil type by Vladimir Volkovintser in the 1970s. Volkovintser argued that the specific properties of these soils are in good agreement with the soil-forming factors: ultracontinental climate, cryoxerophytic steppe or tundra-steppe vegetation, dry permafrost, and skeletal parent material. In cryoaridic soils, the properties of chestnut and pale soils are combined, but their individual features are due to the specific cryohumus AK horizon and secondary carbonates dominated by pendants. Cryoaridic soils were not included in the soviet soil classification system of 1977; in the Russian soil classification system, the type of cryoaridic soils with the AK-BPL-BCA-Cca horizons is included in the order of pale-metamorphic soils with the pale-metamorphic BPL horizon as diagnostic for all soil types of this order. However, our field research, analysis of publications, and the study of soil in the Central Soil Museum give us grounds to verify diagnostic criteria, to change the profile type formula of cryoaridic soils, and to review their taxonomic position in the classification system. We argue that the BPL diagnostic horizon should be replaced by the diagnostic property (pl), which means that cryoaridic soils should be transferred into another order, presumably, the order of humus carbonate-accumulative soils. Some additional subtypes are proposed. On highly skeletal shallow parent materials, cryohumus soils belonging to the order of organo-accumulative soils are developed.
DOI: 10.1134/S1064229322030036
2022054382 Yakovleva, E. V. (Russian Academy of Sciences, Ural Branch, Institute of Biology, Syktyvkar, Russian Federation); Gabov, D. N. and Vasilevich, R. S. Formation of the composition of polycyclic aromatic hydrocarbons in hummocky bogs in the forest-tundra-northern tundra zonal sequence: Eurasian Soil Science, 55(3), p. 313-329, illus. incl. 4 tables, 62 ref., March 2022.
The accumulation of polycyclic aromatic hydrocarbons (PAHs) in plants and peat of three natural subzones - forest-tundra, southern tundra, and northern tundra - is discussed. The content of polyarenes is estimated with high performance liquid chromatography. The absence of statistically significant differences in the PAH accumulation by the plants of the same species in the studied ecotones allows for extrapolation of the data on PAH composition of the studied plants to other background hummocky bogs. The PAH composition of dominant plants influences the PAH composition of the upper peat layers, as is demonstrated by high correlation coefficients. A gradual decomposition of the herbs and trees residues, enriched with lignin, leads to neoformation of heavy polyarene structures (absent in plants) in peat. The coefficients of correlation between peat and plant PAH compositions decrease with depth and the degree of peat decomposition. All studied peatlands display an inverse correlation between the accumulation of naphthalene and benzo[ghi]perylene and the decrease in PAH content in the upper layers of permafrost. The content of polyarenes in the permafrost horizons is determined by the specific historical features in peatland formation. The peak values of five-six ring PAH structures, mainly benzo[ghi]perylene, are observed in the peat layers formed during the Holocene climatic optimum under excessive moistening. As for the raised and transitional bogs having originated during the Subboreal, any increased benzo[ghi]perylene concentrations are unobservable. A decrease in the soil temperatures from south to north is a likely reason for the observed decrease in the PAH content in peatlands from the forest-tundra and southern tundra to northern tundra.
DOI: 10.1134/S1064229322030140
2022053605 Li Yue (Jilin University, College of Earth Sciences, Changchun, China); Wan Zhongmei and Sun Li. Simulation of carbon exchange from a permafrost peatland in the Great Hing'an Mountains based on CoupModel: Atmosphere, 13(1), Article 44, illus. incl. 3 tables, sketch map, 88 ref., January 2022.
Climate change is accelerating its impact on northern ecosystems. Northern peatlands store a considerable amount of C, but their response to climate change remains highly uncertain. In order to explore the feedback of a peatland in the Great Hing'an Mountains to future climate change, we simulated the response of the overall net ecosystem exchange (NEE), ecosystem respiration (ER), and gross primary production (GPP) during 2020-2100 under three representative concentration pathways (RCP2.6, RCP6.0, and RCP8.5). Under the RCP2.6 and RCP6.0 scenarios, the carbon sink will increase slightly until 2100. Under the RCP8.5 scenario, the carbon sink will follow a trend of gradual decrease after 2053. These results show that when meteorological factors, especially temperature, reach a certain degree, the carbon source/sink of the peatland ecosystem will be converted. In general, although the peatland will remain a carbon sink until the end of the 21st century, carbon sinks will decrease under the influence of climate change. Our results indicate that in the case of future climate warming, with the growing seasons experiencing overall dryer and warmer environments and changes in vegetation communities, peatland NEE, ER, and GPP will increase and lead to the increase in ecosystem carbon accumulation.
DOI: 10.3390/atmos13010044
2022050185 Wu Tonghua (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resource, State Key Laboratory of Cryospheric Science, Cryosphere Research Station on the Qinghai-Tibet Plateau, Lanzhou, China); Xie Changwei; Zhu Xiaofan; Chen Jie; Wang Wu; Li Ren; Wen Amin; Wang Dong; Lou Peiqing; Shang Chengpeng; La Yune; Wei Xianhua; Ma Xin; Qiao Yongping; Wu Xiaodong; Pang Qiangqiang and Hu Guojie. Permafrost, active layer, and meteorological data (2010-2020) at the Mahan Mountain relict permafrost site of northeastern Qinghai-Tibet Plateau: Earth System Science Data (ESSD), 14(3), p. 1257-1269, illus. incl. 5 tables, sketch maps, 54 ref., 2022. Part of a special issue entitled extreme environment datasets for the three poles, edited by Carlson, D., et al.
Relict permafrost presents an ideal opportunity to understand the impacts of climatic warming on the ground thermal regime since it is characterized by a mean annual ground temperature close to 0 °C and relatively thin permafrost. The long-term and continuous observations of permafrost thermal state and climate background are of great importance to reveal the links between the energy balance on hourly to annual timescales, to evaluate the variations in permafrost thermal state over multiannual periods and to validate the remote sensing dataset. We present 11 years of meteorological and soil data from the Mahan Mountain relict permafrost site of northeastern Qinghai-Tibet Plateau. The meteorological data comprise air and land surface temperature, relative humidity, wind speed and direction, shortwave and longwave downwards and upwards radiation, water vapor pressure, and precipitation on a half-hour timescale. The active layer data include daily soil temperature and soil volumetric water content at five different depths. The permafrost data consist of the ground temperature at 20 different depths up to 28.4 m. The high-quality and long-term datasets are expected to serve as accurate forcing data in land surface models and evaluate remote-sensing products for a broader geoscientific community. The datasets are available from the National Tibetan Plateau/Third Pole Environment Data Center (URL: https://doi.org/10.11888/Cryos.tpdc.271838, Wu and Xie, 2021).
DOI: 10.5194/essd-14-1257-2022
2022054460 Startsev, V. V. (Russian Academy of Sciences, Ural Branch, Institute of Biology, Syktyvkar, Russian Federation) and Dymov, A. A. Amphiphilic properties and water-soluble organic matter of soils of the subpolar Urals: Eurasian Soil Science, 54(12), p. 1864-1875, illus. incl. 2 tables, 51 ref., December 2021.
Hydrophilic-hydrophobic properties of organic matter and the content and distribution of water-soluble organic matter (WSOM) in soils of the Subpolar Urals are discussed. It is shown that the type of predominant vegetation in the system of altitudinal zones controls the amount and nature of soil organic matter (SOM). The litter of moss-lichen vegetation of the alpine tundra is enriched in hydrophobic compounds (up to 24.0%). In the grass communities of the subalpine zone, hydrophilic fractions of the SOM predominate (first fraction, 42.4-77.0%; second fraction, 0.3-12.6%). Woody vegetation of the mountainous forest zone is specified by an increased content of hydrophobic lignin-containing fractions (16.4-34.8%). Permafrost-affected soils of the alpine tundra are characterized by an increased hydromorphism leading to the accumulation of compounds associated with Fe and Al (up to 75.4%) in mineral horizons. The calculation of the WSOM carbon stock indicates that it reaches 0.3 to 9% of the total carbon stock in the soil profiles.
DOI: 10.1134/S1064229321120127
2022048654 Ji Xiaowen (Nanchang University, School of Resources Environmental & Chemical Engineering, Nanchang, China); Cheng Yu; Abakumov, Evgeny; Zhang, Hao; Han Chao; Tang Rong; Wu Daishe and Xie Xianchuan. Desorption kinetics of heavy metals in the gleyic layer of permafrost-affected soils in Arctic region assessed by geochemical fractionation and DGT/DIFS: Catena (Giessen), 206, Article 105539, illus. incl. 2 tables, sketch map, 57 ref., November 2021.
An in-situ DGT (diffusive gradient in thin films) technique was deployed to gleyic-layer soils identified in the active layer of eight Arctic islands for the release-resupply processes of labile Cd, Zn, and Pb during the thawing season. The capability to maintain the initial soil concentration of these metals is highly dependent upon landscape elevation and soil texture, which determines the labile pool size of metals (Kdl). Cd and Zn had larger labile pools compared to Pb, indicating a larger resupply capacity for those metals. The rate at which the soil system can supply metal from solid phase to solution, represented as response time (Tc), of Zn and Cd was very short (<1 min), indicating rapid resupply. The longer Tc for Pb (~5 min) was consistent with its slower desorption. In fluctuating permafrost-affected areas, the increasing elevation, which causes heterogeneity in soil texture, organic matter, and pH, resulted in lower Kdl and higher Tc for Cd, Zn, and Pb. Combined with BCR methods, labile Cd was associated with Fe oxides, Zn was associated with both Fe and Mn oxides, and Pb was associated with Mn oxides and also highly bound to micro-aggregates and dissolved organic matter.
DOI: 10.1016/j.catena.2021.105539
2022053594 Jin Huijun (Northeast Forestry University, School of Civil Engineering, Institute of Cold-Regions Science and Engineering, Harbin, China) and Ma Qiang. Impacts of permafrost degradation on carbon stocks and emissions under a warming climate; a review: Atmosphere, 12(11), Article 1425, illus. incl. 2 tables, 129 ref., November 2021.
A huge amount of carbon (C) is stored in permafrost regions. Climate warming and permafrost degradation induce gradual and abrupt carbon emissions into both the atmosphere and hydrosphere. In this paper, we review and synthesize recent advances in studies on carbon stocks in permafrost regions, biodegradability of permafrost organic carbon (POC), carbon emissions, and modeling/projecting permafrost carbon feedback to climate warming. The results showed that: (1) A large amount of organic carbon (1460-1600 PgC) is stored in permafrost regions, while there are large uncertainties in the estimation of carbon pools in subsea permafrost and in clathrates in terrestrial permafrost regions and offshore clathrate reservoirs; (2) many studies indicate that carbon pools in Circum-Arctic regions are on the rise despite the increasing release of POC under a warming climate, because of enhancing carbon uptake of boreal and arctic ecosystems; however, some ecosystem model studies indicate otherwise, that the permafrost carbon pool tends to decline as a result of conversion of permafrost regions from atmospheric sink to source under a warming climate; (3) multiple environmental factors affect the decomposability of POC, including ground hydrothermal regimes, carbon/nitrogen (C/N) ratio, organic carbon contents, and microbial communities, among others; and (4) however, results from modeling and projecting studies on the feedbacks of POC to climate warming indicate no conclusive or substantial acceleration of climate warming from POC emission and permafrost degradation over the 21st century. These projections may potentially underestimate the POC feedbacks to climate warming if abrupt POC emissions are not taken into account. We advise that studies on permafrost carbon feedbacks to climate warming should also focus more on the carbon feedbacks from the rapid permafrost degradation, such as thermokarst processes, gas hydrate destabilization, and wildfire-induced permafrost degradation. More attention should be paid to carbon emissions from aquatic systems because of their roles in channeling POC release and their significant methane release potentials.
DOI: 10.3390/atmos12111425
2022053596 Timofeev, Andrey (Data Processing Laboratory, EqualiZoom, Nur-Sultan, Kazakhstan); Piirainen, Viktor; Bazhin, Vladimir and Titov, Aleksander. Operational analysis and medium-term forecasting of the greenhouse gas generation intensity in the cryolithozone: Atmosphere, 12(11), Article 1466, illus. incl. 5 tables, 5 tables, 21 ref., November 2021.
We proposed a new approach to solving the problem of operational analysis and medium-term forecasting of the greenhouse gas generation (CO2, CH4) intensity in a certain area of the cryolithozone using data from a geographically distributed network of multimodal measuring stations. A network of measuring stations, capable of functioning autonomously for long periods of time, continuously generated a data flow of the CO2, CH4 concentration, soil moisture, and temperature, as well as a number of other parameters. These data, taking into account the type of soil, were used to build a spatially distributed dynamic model of greenhouse gas emission intensity of the permafrost area depending on the temperature and moisture of the soil. This article presented models for estimating and medium-term predicting ground greenhouse gases emission intensity, which are based on artificial intelligence methods. The results of the numerical simulations were also presented, which showed the adequacy of the proposed approach for predicting the intensity of greenhouse gas emissions.
DOI: 10.3390/atmos12111466
2022055467 Pravalie, Remus (University of Bucharest, Faculty of Geography, Bucharest, Romania). Exploring the multiple land degradation pathways across the planet: Earth-Science Reviews, 220, Article 103689, illus. incl. sketch maps, 523 ref., September 2021.
Land degradation has become one of the biggest environmental challenges human society is currently facing, which is why understanding the global pattern of this land crisis is absolutely necessary. However, so far, the multiple forms of this environmental issue have mainly been analysed in international scientific literature in a narrow traditional manner, frequently based on approaching a relatively low number of ordinary land degradation processes. Consequently, as this complex process has not been sufficiently well explored, this study aims to investigate global land degradation in an interdisciplinary and holistic manner, in terms of the multidimensional nature, causes, spatial footprint, multiple consequences (for the ecological and anthropogenic systems worldwide, but also for the global climate system) and various solutions to mitigate worldwide land multi-degradation. Based on various information investigated in more than 500 reliable scientific papers, the findings of this review paper showed that there currently are 17 land degradation pathways (aridity, biological invasions, coastal erosion, land erosion by water, land erosion by wind, land pollution, land subsidence, landslides, permafrost thawing, salinization, soil acidification, soil biodiversity loss, soil compaction, soil organic carbon loss, soil sealing, vegetation degradation and waterlogging), which are active on various spatial scales across the planet. Five of the seventeen land degradation dimensions were considered major land degradation pathways and explored in detail in this study (aridity, land erosion by water, salinization, soil organic carbon loss and vegetation degradation), considering several relevant criteria outlined in the paper (global spatial footprint, data availability, and impact on agricultural, ecological and climate systems). Essentially, it was found that the five global degradation processes significantly erode the multiple ecosystem functions and services of worldwide land systems, which are crucial for human wellbeing, life support and the Earth systems' stability. Nonetheless, other land degradation processes can also be considered major land degradative pathways, although a main current impediment in their detailed investigation is the general lack of global data availability. Therefore, the study highlights the complexity and severity of global land degradation, and draws attention to the need for other studies to approach land degradation multidimensionally, which goes beyond the traditional perspectives focused on the conventional processes of water erosion, wind erosion or soil salinization. At the same time, the study highlights the fact that land degradation must be an urgent priority in governmental and international policies, which can rely on a wide range of control measures that are currently available (some of the relevant ones are explored in this paper) for combating this disrupting environmental process rapidly, efficiently and on a large scale throughout the world.
DOI: 10.1016/j.earscirev.2021.103689
2022053147 Zhou Bingrong (Qinghai Institute of Meteorology Science, Qinghai Provincial Meteorological Bureau, Key Laboratory of Disaster Prevention and Mitigation of Qinghai Province, Xining, China); Wu Liang; Song Minghua; Zhou Huakun; Li Yikang; Wang Min; Zhang Tingjun; Yan Yuqian and Ji Haijuan. Distinct climate driven spatial patterns of frozen soil and vegetation that reflect plant sensitivities across the Tibetan Plateau: Land Degradation & Development, 32(15), p. 4227-4240, illus., 54 ref., September 2021.
Earth's cryosphere and biosphere are extremely sensitive to climate changes, and transitions in states could alter the carbon emission rate to the atmosphere. However, little is known about the climate sensitivities of frozen soil and vegetation production. Moreover, how does climate heterogeneity control the spatial patterns of such sensitivities, and influence regional vulnerability of both frozen soil and vegetation production? Such questions are critical to be answered. We compiled long-time-series dataset including frozen soil depth (FD), normalized difference vegetation index (NDVI), and temperature and precipitation across Tibetan Plateau to quantify their sensitivities. Results reveal large spatial heterogeneity in FD and NDVI sensitivities. Precipitation alleviated FD sensitivities to warming in the cold northeast zone but accelerated FD sensitivities to precipitation in the warm south and southeast. Meanwhile, the positive warming effect on the NDVI was largely offset by slow increase of precipitation. Areas with high FD decreasing rate were found in northeast, inland, and south and southeast zones. Predominate area across the nine eco-regions are characterized as medium FD decreasing rate, and are synchronized with positive NDVI response in inland and west Himalayas, but negative in northeast and south and southeast. Precipitation restriction on NDVI would be pronounced in moist south and southeast. Our study provides new information that makes a much-needed contribution to advancing our understandings of the effects of global climate change on cryosphere and biosphere, which has important implications for global climate and our ability to predict, and therefore prepare for, future global climatic changes. Our attempt confirms that the method we used could be used to identify climate sensitivity of permafrost based on substantial observation data on active layer dynamics in future. Abstract Copyright (2021), John Wiley & Sons, Ltd.
DOI: 10.1002/ldr.4029
2022053589 Sun Xiaoxin (Northeast Forestry University, Key Laboratory of Sustainable Forest Ecosystem Management, Harbin, China); Wang, Hongjun; Song Changchun; Jin Xin; Richardson, Curtis J. and Cai Tijiu. Response of methane and nitrous oxide emissions from peatlands to permafrost thawing in Xiaoxing'an Mountains, northeast China: Atmosphere, 12(2), Article 222, illus. incl. 3 tables, 75 ref., February 2021.
Permafrost thawing may lead to the release of carbon and nitrogen in high-latitude regions of the Northern Hemisphere, mainly in the form of greenhouse gases. Our research aims to reveal the effects of permafrost thawing on CH4 and N2O emissions from peatlands in Xiaoxing'an Mountains, northeast China. During four growing seasons (2011-2014), in situ CH4 and N2O emissions were monitored from peatland under permafrost no-thawing, mild-thawing, and severe-thawing conditions in the middle of the Xiaoxing'an Mountains by a static-chamber method. Average CH4 emissions in the severe-thawing site were 55-fold higher than those in the no-thawing site. The seasonal variation of CH4 emission became more aggravated with the intensification of permafrost thawing, in which the emission peaks became larger and the absorption decreased to zero. The increased CH4 emissions were caused by the expansion of the thawing layer and the subsequent increases in soil temperature, water table, and shifts of plant communities. However, N2O emissions did not change with thawing. Permafrost thawing increased CH4 emissions but did not impact N2O emissions in peatlands in the Xiaoxing'an Mountains. Increased CH4 emissions from peatlands in this region may amplify global warming.
DOI: 10.3390/atmos12020222
2022053584 Ramos, Miguel (University of Alcalá, Department of Physics and Mathematics, Alcala de Henares, Spain); Vieira, Goncalo; de Pablo, Miguel Angel; Molina, Antonio and Jimenez, Juan Javier. Transition from a subaerial to a subnival permafrost temperature regime following increased snow cover (Livingston Island, Maritime Antarctic): Atmosphere, 11(12), Article 1332, illus. incl. 6 tables, sketch map, 35 ref., December 2020.
The Antarctic Peninsula (AP) region has been one of the regions on Earth with strongest warming since 1950. However, the northwest of the AP showed a cooling from 2000 to 2015, which had local consequences with an increase in snow accumulation and a deceleration in the loss of mass from glaciers. In this paper, we studied the effects of increased snow accumulation in the permafrost thermal regime in two boreholes (PG1 and PG2) in Livingston Island, South Shetlands Archipelago, from 2009 to 2015. The two boreholes located c. 300 m apart but at similar elevation showed different snow accumulation, with PG2 becoming completely covered with snow all year long, while the other remained mostly snow free during the summer. The analysis of the thermal regimes and of the estimated soil surface energy exchange during the study period showed the effects of snow insulation in reducing the active layer thickness. These effects were especially relevant in PG2, which transitioned from a subaerial to a subnival regime. There, permafrost aggraded from below, with the active layer completely disappearing and the efficiency of thermal insulation by the snowpack prevailing in the thermal regime. This situation may be used as an analogue for the transition from a periglacial to a subglacial environment in longer periods of cooling in the paleoenvironmental record.
DOI: 10.3390/atmos11121332
2022053068 Rao Zhiguo (Hunan Normal University, College of Resources and Environmental Sciences, Changsha, China); Guo Haichun; Cao Jiantao; Shi Fuxi; Jia Guodong; Li Yunxia and Chen Fahu. Consistent long-term Holocene warming trend at different elevations in the Altai Mountains in arid Central Asia: JQS. Journal of Quaternary Science, 35(8), p. 1036-1045, illus. incl. strat. cols., 1 table, sketch map, 47 ref., November 2020.
Recent results indicate contrasting Holocene moisture histories at different elevations in arid central Asia (ACA). However, relatively little is known about Holocene temperature changes at different elevations. Here we report an independently dated peat brGDGTs-based MBT'5ME record from the Narenxia peatland (NRX) in the southern Altai Mountains. The record suggests a long-term warming trend since »7.7 cal. kyr bp, with a warmer stage during »7-5.5 cal. kyr bp, a cold stage during »5.5-4 cal. kyr bp, and a warming trend over the last »4 kyr. The long-term warming trend indicated by the NRX MBT'5ME record is largely consistent with Holocene temperature records from nearby sites covering an altitudinal range of »1700-4100 m above sea level. This consistent long-term warming trend at different elevations differs from the long-term Holocene drying/wetting trends at high/low elevations of the Altai Mountains. We propose that the warming trend and consequent permafrost thawing at high elevations could have resulted in increased meltwater runoff, which would have contributed to the long-term wetting trend at low elevations. Our findings potentially provide an improved understanding of regional climate change and associated water resource availability, with implications for their possible future status. Abstract Copyright (2021), John Wiley & Sons, Ltd.
DOI: 10.1002/jqs.3254
2022053573 Munkhjargal, Munkhdavaa (Heidelberg University, Professorship in Hydrology and Climatology, Institute of Geography, Heidelberg, Germany); Yadamsuren, Gansukh; Yamkhin, Jambaljav and Menzel, Lucas. The combination of wildfire and changing climate triggers permafrost degradation in the Khentii Mountains, northern Mongolia: Atmosphere, 11(2), Article 155, illus. incl. 4 tables, sketch map, 47 ref., February 2020.
High topographic heterogeneity and complex mechanisms between the atmosphere and the ground create unique hydro-climatic processes over mountainous regions. Based on in situ observations, we present the spatial variability of ground surface temperature (GST) in the Khentii Mountains of northern Mongolia, which is situated at the southern fringe of the Eurasian permafrost zone. Changes in the hydrothermal regime of the active layer were investigated in association with changing climate and wildfire effects. The results reveal that the GST tends to increase continuously since 2011 in both thawing and freezing seasons, and varies significantly within a short horizontal distance, particularly during the thawing season. Extreme weather events, such as drought and heavy snowfall, amplify the increase in the ground temperature and deepen the seasonal thawing depth. The fire-induced loss in organic layer resulted in a greater heat penetration deeper into the ground and unbalanced the moisture distribution. Overall, the thawing depth is greater by >1.7 m under severely burned forest, compared to unburned forest. Given that about 30% of the boreal forest was affected by wildfire in the study area, the ground thermal regime changed considerably. The findings suggest that the combination of regional temperature rise and more frequent extreme weather and wildfire events in the region triggers permafrost degradation and alters the hydrothermal regime in the future.
DOI: 10.3390/atmos11020155
2022049936 Thalasso, Frederic (Cinvestav, Biotechnology and Bioengineering Department, Mexico City, Mexico); Anthony, Katey Walter; Irzak, Olya; Chaleff, Ethan; Barker, Laughlin; Anthony, Peter; Hanke, Philip and Gonzalez-Valencia, Rodrigo. Mobile open dynamic chamber measurement of methane macroseeps in lakes: Hydrology and Earth System Sciences (HESS), 24(12), p. 6047-6058, illus. incl. geol. sketch map, 47 ref., 2020. Technical note.
Methane (CH4) seepage (i.e., steady or episodic flow of gaseous hydrocarbons from subsurface reservoirs) has been identified as a significant source of atmospheric CH4. However, radiocarbon data from polar ice cores have recently brought into question the magnitude of fossil CH4 seepage naturally occurring. In northern high latitudes, seepage of subsurface CH4 is impeded by permafrost and glaciers, which are under an increasing risk of thawing and melting in a globally warming world, implying the potential release of large stores of CH4 in the future. Resolution of these important questions requires a better constraint and monitoring of actual emissions from seepage areas. The measurement of these seeps is challenging, particularly in aquatic environments, because they involve large and irregular gas flow rates, unevenly distributed both spatially and temporally. Large macroseeps are particularly difficult to measure due to a lack of lightweight, inexpensive methods that can be deployed in remote Arctic environments. Here, we report the use of a mobile chamber for measuring emissions at the surface of ice-free lakes subject to intense CH4 macroseepage. Tested in a remote Alaskan lake, the method was validated for the measurement of fossil CH4 emissions of up to 1.08 ´ 104g CH4m-2d-1 (13.0Lm-2min-2min-1 of 83.4% CH4 bubbles), which is within the range of global fossil methane seepage and several orders of magnitude above standard ecological emissions from lakes. In addition, this method allows for low diffusive flux measurements. Thus, the mobile chamber approach presented here covers the entire magnitude range of CH4 emissions currently identified, from those standardly observed in lakes to intense macroseeps, with a single apparatus of moderate cost.
DOI: 10.5194/hess-24-6047-2020
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The USPA is pleased to announce the availability of an updated searchable database on permafrost-related publications. The American Geosciences Institute (AGI), with support from the National Science Foundation (NSF), has migrated the previous Cold Regions Bibliography to a new platform. Included are the USPA supported PMAs dating back to 2011. The Bibliography is searchable at 
