Permafrost Monthly Alerts (PMAs)

2018018635 Appels, Willemijn M. (University of Saskatchewan, Global Institute for Water Security, Saskatoon, SK, Canada); Coles, Anna E. and McDonnell, Jeffrey J. Infiltration into frozen soil; from core-scale dynamics to hillslope-scale connectivity: Hydrological Processes, 32(1), p. 66-79, illus. incl. 1 table, 67 ref., January 1, 2018.

Infiltration into frozen soil is a key hydrological process in cold regions. Although the mechanisms behind point-scale infiltration into frozen soil are relatively well understood, questions remain about upscaling point-scale results to estimate hillslope-scale run-off generation. Here, we tackle this question by combining laboratory, field, and modelling experiments. Six large (0.30-m diameter by 0.35-m deep) soil cores were extracted from an experimental hillslope on the Canadian Prairies. In the laboratory, we measured run-off and infiltration rates of the cores for two antecedent moisture conditions under snowmelt rates and diurnal freeze-thaw conditions observed on the same hillslope. We combined the infiltration data with spatially variable data from the hillslope, to parameterise a surface run-off redistribution model. We used the model to determine how spatial patterns of soil water content, snowpack water equivalent (SWE), and snowmelt rates affect the spatial variability of infiltration and hydrological connectivity over frozen soil. Our experiments showed that antecedent moisture conditions of the frozen soil affected infiltration rates by limiting the initial soil storage capacity and infiltration front penetration depth. However, shallow depths of infiltration and refreezing created saturated conditions at the surface for dry and wet antecedent conditions, resulting in similar final infiltration rates (0.3 mm hr^-1). On the hillslope-scale, the spatial variability of snowmelt rates controlled the development of hydrological connectivity during the 2014 spring melt, whereas SWE and antecedent soil moisture were unimportant. Geostatistical analysis showed that this was because SWE variability and antecedent moisture variability occurred at distances shorter than that of topographic variability, whereas melt variability occurred at distances longer than that of topographic variability. The importance of spatial controls will shift for differing locations and winter conditions. Overall, our results suggest that run-off connectivity is determined by (a) a pre-fill phase, during which a thin surface soil layer wets up, refreezes, and saturates, before infiltration excess run-off is generated and (b) a subsequent fill-and-spill phase on the surface that drives hillslope-scale run-off. Abstract Copyright (2010), John Wiley & Sons, Ltd.

DOI: 10.1002/hyp.11399

2018014291 Tai Bowen (Beijing Jiaotong University, School of Civil Engineering, Beijing, China); Liu Jiankun; Yue Zurun; Liu Jingyu; Tian Yahu and Wang Tengfei. Effect of sunny-shady slopes and strike on thermal regime of subgrade along a high-speed railway in cold regions, China: Engineering Geology, 232, p. 182-191, illus. incl. 2 tables, sketch map, 54 ref., January 8, 2018.

Ground temperature and deformation of embankment were monitored at typical sections of the Harbin-Qiqihar high speed railway (HSR) to investigate complex causes of differential embankment deformation due to sunny-shady slopes and route strike in cold regions. Maximum frozen depth, ground temperature, frost heave, and thaw settlement of the embankment in the sunny and shady sides were analyzed relative to measurement dates, and then a numerical model for the embankment temperature filed was also established. On these bases, the influence of route strike on the embankment thermal regime and its mechanism were then revealed; and proper engineering countermeasures were proposed to mitigate the transverse embankment thermal difference; the formation mechanism of the differential deformation due to sunny-shady slopes was discussed. The results showed that both temperature and maximum frozen depth of the sunny side were greater than the shady side, whereas the cumulative frost heave of the sunny side was less than the shady side with opposite trends found for the cumulative thaw settlement. The temperature difference between the sunny and shady shoulders decreased gradually with increasing strike angle. The findings are potentially helpful for better understanding differential embankment deformation in cold regions, as well as for improving HSR embankment quality and operational safety.

DOI: 10.1016/j.enggeo.2017.09.002

2018018629 Qin Yanhui (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Lanzhou, China); Wu Tonghua; Wu Xiaodong; Li Ren; Xie Changwei; Qiao Yongping; Hu Guojie; Zhu Xiaofan; Wang Weihua and Shang Wen. Assessment of reanalysis soil moisture products in the permafrost regions of the central of the Qinghai-Tibet Plateau: Hydrological Processes, 31(26), p. 4647-4659, illus. incl. 3 tables, sketch map, 100 ref., December 30, 2017.

The long-term and large-scale soil moisture (SM) record is important for understanding land atmosphere interactions and their impacts on the weather, climate, and regional ecosystem. SM products are one of the parameters used in some Earth system models, but these records require evaluation before use. The water resources on the Qinghai-Tibet Plateau (QTP) are important to the water security of billions of people in Asia. Therefore, it is necessary to know the SM conditions on the QTP. In this study, the evaluation metrics of multilayer (0-10, 10-40, and 40-100 cm) SM in different reanalysis datasets of the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim [ERA]), National Centers for Environmental Prediction Climate Forecast System and the Climate Forecast System version 2 (CFSv2), and China Meteorological Administration Land Data Assimilation System (CLDAS) are compared with in situ observations at 5 observation sites, which represent alpine meadow, alpine swamp meadow, alpine grassy meadow, alpine desert steppe, and alpine steppe environments during the thawing season from January 1, 2011, to December 31, 2013, on the QTP. The ERA SM remains constant at approximately 0.2 m³·m^-3 at all observation sites during the entire thawing season. The CLDAS and CFSv2 SM products show similar patterns with those of the in situ SM observations during the thawing season. The CLDAS SM product performs better than the CFSv2 and ERA for all vegetation types except the alpine swamp meadow. The results indicate that the soil texture and land cover types play a more important role than the precipitation to increase the biases of the CLDAS SM product on the QTP. Abstract Copyright (2010), John Wiley & Sons, Ltd.

DOI: 10.1002/hyp.11383

2018016831 Huang Yan (East China Normal University, Laboratory of Geographic Information Science, Shanghai, China); Liu Hongxing; Hinkel, Kenneth; Yu Bailang; Beck, Richard and Wu Jianping. Analysis of thermal structure of Arctic lakes at local and regional scales using in situ and multidate Landsat-8 data: Water Resources Research, 53(11), p. 9642-9658, illus. incl. 2 tables, sketch map, 53 ref., November 2017.

The Arctic coastal plain is covered with numerous thermokarst lakes. These lakes are closely linked to climate and environmental change through their heat and water budgets. We examined the intralake thermal structure at the local scale and investigated the water temperature pattern of lakes at the regional scale by utilizing extensive in situ measurements and multidate Landsat-8 remote sensing data. Our analysis indicates that the lake skin temperatures derived from satellite thermal sensors during most of the ice-free summer period effectively represent the lake bulk temperature because the lakes are typically well-mixed and without significant vertical stratification. With the relatively high-resolution Landsat-8 thermal data, we were able to quantitatively examine intralake lateral temperature differences and gradients in relation to geographical location, topography, meteorological factors, and lake morphometry for the first time. Our results suggest that wind speed and direction not only control the vertical stratification but also influences lateral differences and gradients of lake surface temperature. Wind can considerably reduce the intralake temperature gradient. Interestingly, we found that geographical location (latitude, longitude, distance to the ocean) and lake morphometry (surface size, depth, volume) not only control lake temperature regionally but also affect the lateral temperature gradient and homogeneity level within each individual lake. For the Arctic coastal plain, at regional scales, inland and southern lakes tend to have larger horizontal temperature differences and gradients compared to coastal and northern lakes. At local scales, large and shallow lakes tend to have large lateral temperature differences relative to small and deep lakes. Abstract Copyright (2017), . American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2017WR021335

2018013789 Lehn, Gregory O. (Northwestern University, Department of Earth and Planetary Sciences, Evanston, IL); Jacobson, A. D.; Douglas, T. A.; McClelland, J. W.; Barker, A. J. and Khosh, M. S. Constraining seasonal active layer dynamics and chemical weathering reactions occurring in North Slope Alaskan watersheds with major ion and isotope (d³⁴S_SO4, d¹³C_DIC, ⁸⁷Sr/⁸⁶Sr, d^44/40Ca, and d^44/42Ca) measurements: Geochimica et Cosmochimica Acta, 217, p. 399-420, illus. incl. sketch map, 185 ref., November 15, 2017. Includes appendices.

Rising air temperatures in the Arctic may destabilize a large pool of organic carbon stored in permafrost, thereby causing a positive feedback to global climate warming. Permafrost thaw could also deepen hydrologic flow paths and expose previously frozen rock and mineral fragments to chemical weathering. Future shifts in the inorganic solute geochemistry of Arctic rivers may signal changes in soil processes that also affect organic carbon storage. Tracing permafrost thaw with dissolved riverine loads requires understanding the spatial and seasonal variation of chemical weathering reactions and other biogeochemical phenomena that affect elemental mass-transport. To help identify connections between mineral weathering and active layer processes, we studied the major ion and isotope (d³⁴S_SO4, d¹³C_DIC, ⁸⁷Sr/⁸⁶Sr, d^44/40Ca, and d^44/42Ca) geochemistry of five streams draining the North Slope of Alaska. Continuous permafrost underlies all streams, but the Atigun River, Roche Moutonnee Creek, and Trevor Creek primarily drain bare bedrock outcrops in the Brooks Range, while the Upper Kuparuk River and Imnavait Creek primarily drain tundra. In total, we collected 546 water samples spanning the spring freshet through fall freeze-up in 2009 and 2010. We also analyzed snow, rock, sediment, soil, and plant samples. Major ion ratios and d¹³C_DIC values point to the overall dominance of carbonate weathering by carbonic and sulfuric acids, with additional influences from atmospheric deposition, plant decay, sulfate salt dissolution, and silicate weathering by carbonic acid. d¹³C_DIC values may also reflect partial equilibration with soil and atmospheric CO₂. All streams display large seasonal variations in major ion ratios and d¹³C_DIC values that are consistent with progressive deepening of the seasonally thawed zone over the summer. In the mountain watersheds, carbonate weathering dominates during the spring and summer, while sulfate salt (primarily CaSO₄ and MgSO₄) dissolution dominates during the fall. Riverine d³⁴S_SO4 values reveal that the sulfate salts are secondary precipitates. We propose a conceptual model where cryoconcentration in soils during the late fall and winter causes secondary mineral formation at depth and re-exposure during subsequent thaw seasons produces the observed geochemical signals in rivers. The tundra streams lack definitive evidence for sulfate salt dissolution, presumably because thick peat soils limit the exposure and weathering of underlying glacial sediment where the salts are expected to form and dissolve. Appearance of a sulfate salt dissolution signal in tundra streams may correlate with future permafrost degradation. Carbonate weathering dominates riverine ⁸⁷Sr/⁸⁶Sr ratios, but the compositional heterogeneity of bedrock limits interpretation of the data. All rivers have higher d^44/40Ca values compared to bedrock, likely due to plant uptake of lighter Ca isotopes. In the tundra watersheds, freshet d^44/40Ca values were 0.10-0.20 ppm lower than summer and fall values. These trends likely reflect contributions from plant decay, as comparison between d^44/40Ca and d^44/42Ca values suggests that all isotopic variation is mass-dependent with minimal radiogenic ⁴⁰Ca inputs from the weathering of old silicate minerals with high K/Ca ratios.

DOI: 10.1016/j.gca.2017.07.042

2018013850 Loiko, Sergey V. (Tomsk State University, Laboratory of Biogeochemical and Remote Monitoring Techniques Enviornment, Tomsk, Russian Federation); Pokrovsky, Oleg S.; Raudina, Tatiana V.; Lim, Artyom; Kolesnichenko, Larisa G.; Shirokova, Liudmila S.; Vorobyev, Sergey N. and Kirpotin, Sergey N. Abrupt permafrost collapse enhances organic carbon, CO₂, nutrient and metal release into surface waters: Chemical Geology, 471, p. 153-165, illus. incl. 3 tables, sketch map, 81 ref., November 5, 2017. Includes appendices.

Thawing of frozen peat in discontinuous permafrost zones may significantly modify the environment at local (slumps and engineering damages) and global (greenhouse gases regime) scales. We studied the aquatic geochemistry of CO₂, CH₄, dissolved organic carbon (DOC), P, Si, and colloidal trace metal from hollows, depressions, permafrost subsidences and soil waters in the actively thawing discontinuous permafrost zone of Western Siberia Lowland (WSL). This site of abrupt permafrost collapse is dominated by minerotrophic fens located within the flat mound peat bog. The CO₂, DOC, major and trace metal concentrations decreased with the increase of the surface area of the water body, along the hydrological continuum (soil water ® hollows ® depressions and permafrost subsidences ® thaw ponds ® thermokarst lakes). Aqueous concentrations of CO₂, CH₄, Ca, Si, P, Al, Fe, Nd, and U were a factor of 4 to 10 higher in the site of catastrophic thaw compared to the steady thawing of a palsa peat bog that was previously studied in the same region. The colloids (1 kDa-0.45 mm) formed in hot spots were strongly enriched in Fe, Al, and trivalent and tetravalent hydrolysates relative to organic carbon. Because the increase in the thickness of the thawing depth intensifies the input of inorganic components from deep mineral horizons, abrupt permafrost thaw enriches the surface waters in Al-rich colloids and low molecular weight organic complexes. As a result, the WSL's surface water colloidal composition may shift from DOM-rich and DOM-Fe-rich to DOM-Al-rich, and the release of low-soluble trivalent and tetravalent hydrolysates from the soil to the river will increase. We hypothesize that in sites of abrupt permafrost thaw, there is direct mobilization of soil waters to a hydrological network (rivers and lakes) and there is minimal transformation by autochthonous processes, which is unlike the case of steady permafrost thawing. Therefore, the change in physical factors, such as water pathways and the water residence time, within a given elementary landscape will likely control the overall impact of on-going permafrost thaw on both the surface water chemistry and dissolved greenhouse gas pattern of the territory. For this, high-resolution (< 2 m) remote sensing analysis of water dynamics in the permafrost landscape is necessary.

DOI: 10.1016/j.chemgeo.2017.10.002

2018018311 Pratt, Dyan L. (University of Saskatchewan, Global Institute for Water Security, Saskatoon, SK, Canada) and McDonnell, Jeffrey J. A portable experimental hillslope for frozen ground studies: Hydrological Processes, 31(24), p. 4450-4457, illus. incl. 1 table, 26 ref., November 30, 2017. Includes appendices.

Frozen ground hydrological effects on runoff, storage, and release have been observed in the field and tested in numerical models, but few physical models of frozen slopes (at scales from 1 to 15 m) exist partly because the design of such an experiment requires new engineering design for realistic whole-slope freezing and physical model innovation. Here, we present a new freezable tilting hillslope physical model for hydrological system testing under a variety of climate conditions with the ability to perform multiple (up to 20 per year) freeze-thaw cycles. The 4 ´ 2 m hillslope is mobile and tiltable on the basis of a modified tri-axle 4.88-m (16') dump trailer to facilitate testing multiple configurations. The system includes controllable boundary conditions on all surfaces; examples of side and baseflow boundary conditions include permeable membranes, impermeable barriers, semipermeable configurations, and constant head conditions. To simulate cold regions and to freeze the hillslope in a realistic and controlled manner, insulation and a removable freezer system are incorporated onto the top boundary of the hillslope. The freezing system is designed to expedite the freezing process by the addition of a 10,130-KJ (9,600-BTU) refrigeration coil to the top-centre of the insulated ceiling. Centre placement provides radial freezing of the hillslope in a top-down fashion, similar to what natural systems encounter in the environment. The perimeter walls are insulated with 100 mm of spray foam insulation, whereas the base of the hillslope is not insulated to simulate natural heat fluxes beneath the frozen layer of soil. Our preliminary testing shows that covers can be frozen down to -10 °C in approximately 7 days, with subsequent thaw on a similar time frame. Abstract Copyright (2010), John Wiley & Sons, Ltd.

DOI: 10.1002/hyp.11284

2018013902 You Yanhui (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Wang Jinchang; Wu Qingbai; Yu Qihao; Pan Xicai; Wang Xinbin and Guo Lei. Causes of pile foundation failure in permafrost regions; the case study of a dry bridge of the Qinghai-Tibet Railway: Engineering Geology, 230, p. 95-103, illus. incl. sects., sketch map, 46 ref., November 29, 2017.

Pile foundations are widely used to support dry bridges crossing large extents of warm and ice-rich permafrost zones along the Qinghai-Tibet Railway (QTR). The performance of these pile foundations are related to permafrost conditions surrounding the piles. However, the impacts of permafrost degradation on the stability of pile foundations have been rarely investigated. In this study, permafrost degradation has been assessed around several pile foundations in the Tanggula Mountain area along the QTR 15 years after the first field investigation in 2001 for the construction of the QTR. This assessment is mainly based on drilling, geophysical surveys, and monitoring of the settlements affecting the pile foundations. The permafrost in contact with the piles has significantly thinned after the piles were casted-in-place and put into service about 8 years ago. Moreover, the thickness of residual permafrost is less than the embedment length for some piles and, therefore, the adfreeze bond between the piles and permafrost has significantly decreased. In addition, artesian sub-permafrost groundwater has been observed around the middle-lower and below the piles. Due to this sub-permafrost aquifer, the end bearing capacity of the piles and the friction between the piles and thawed soils have also probably decreased. The applied load on the piles is now supported by the residual permafrost resulting in large settlements of the piles. The thaw consolidation and settlement of degrading permafrost have also potentially contributed to the total settlement. According to the investigation presented herein, the occurrence of sub-permafrost aquifer which was induced by permafrost degradation is the primary cause of pile settlements. The failure mechanisms of the piles as revealed by this assessment are useful for the design and maintenance of piles in warm and ice-rich permafrost regions. Moreover, the use of geophysical methods for investigating pile foundation failure due to permafrost degradation has proved effective.

DOI: 10.1016/j.enggeo.2017.10.004

2018010680 Ban Yunyun (China Agricultural University, College of Water Resources and Civil Engineering, Beijing, China); Lei Tingwu; Chen Chao; Yin Zhe and Qian Dengfeng. Meltwater erosion process of frozen soil as affected by thawed depth under concentrated flow in high altitude and cold regions: Earth Surface Processes and Landforms, 42(13), p. 2139-2146, illus. incl. 3 tables, 45 ref., October 2017.

Changes in thawed depth of frozen soil caused by diurnal and seasonal temperature fluctuations are commonly found in high altitude and latitude regions of the world. These changes significantly influence hydrologic and erosion processes. Experimental data are necessary to improve the understanding and modeling of the phenomenon. Laboratory experiments were conducted in Beijing to assess the impacts of thawed soil depth, slope gradient, and flow rate on soil erosion by concentrated meltwater flow over an underlying frozen soil layer. Soil samples from watershed were filled in flumes, saturated before being frozen. After the soil was completely frozen, flumes were taken out of storage to thaw the frozen soil from top to the designed depths. Meltwater flow was simulated using a tank filled with water and icecubes at approximately 0°C. The erosion experiments involved four thawed soil depths of 1, 2, 5, and 10 cm; three slope gradients of 5°, 10°, and 15°; and three flow rates of 1, 2, and 4 l/min; and seven rill lengths of 0.5, 1, 2, 3, 4, 5, and 6 m. Sediment-laden water samples were collected at the lower end of the flume for determination of sediment concentration. The results showed that sediment concentration increased exponentially with rill length to approach a maximum value. The sediment concentrations were closely correlated with thawed soil depth, flow rate, and slope gradient. Shallower thawed depths delivered more sediments than deeper thawed depths. Slope gradient was the primary factor responsible for severe erosion. The effect of flow rate on sediment concentration which decreased with increasing slope gradient, was not as significant as that of slope gradient. Results from these experiments are useful for understanding the effect of thawed soil depth on erosion process in thawed soils subject to freezing and for estimating erosion model parameters. Copyright Copyright 2017 John Wiley & Sons, Ltd.

DOI: 10.1002/esp.4173

2018010161 Riedel, M. (Leibniz Institute for Marine Sciences, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany); Brent, T. A.; Taylor, G.; Taylor, A. E.; Hong, J. K.; Jin, Y. K. and Dallimore, S. R. Evidence for gas hydrate occurrences in the Canadian Arctic Beaufort Sea within permafrost-associated shelf and deep-water marine environments: Marine and Petroleum Geology, 81, p. 66-78, illus. incl. sects., sketch map, 58 ref., March 2017.

The presence of a wedge of offshore permafrost on the shelf of the Canadian Beaufort Sea has been previously recognized and the consequence of a prolonged occurrence of such permafrost is the possibility of an underlying gas hydrate regime. We present the first evidence for wide-spread occurrences of gas hydrates across the shelf in water depths of 60-100 m using 3D and 2D multichannel seismic (MCS) data. A reflection with a polarity opposite to the seafloor was identified ~1000 m below the seafloor that mimics some of the bottom-simulating reflections (BSRs) in marine gas hydrate regimes. However, the reflection is not truly bottom-simulating, as its depth is controlled by offshore permafrost. The depth of the reflection decreases with increasing water depth, as predicted from thermal modeling of the late Wisconsin transgression. The reflection crosscuts strata and defines a zone of enhanced reflectivity beneath it, which originates from free gas accumulated at the phase boundary over time as permafrost and associated gas hydrate stability zones thin in response to the transgression. The wide-spread gas hydrate occurrence beneath permafrost has implications on the region including drilling hazards associated with the presence of free gas, possible overpressure, lateral migration of fluids and expulsion at the seafloor. In contrast to the permafrost-associated gas hydrates, a deep-water marine BSR was also identified on MCS profiles. The MCS data show a polarity-reversed seismic reflection associated with a low-velocity zone beneath it. The seismic data coverage in the southern Beaufort Sea shows that the deep-water marine BSR is not uniformly present across the entire region. The regional discrepancy of the BSR occurrence between the US Alaska portion and the Mackenzie Delta region may be a result of high sedimentation rates expected for the central Mackenzie delta and high abundance of mass-transport deposits that prohibit gas to accumulate within and beneath the gas hydrate stability zone.

DOI: 10.1016/j.marpetgeo.2016.12.027

2018015691 Daout, Simon (Université Grenoble-Alpes, Institut des Sciences de la Terre, Grenoble, France); Doin, Marie-Pierre; Peltzer, Gilles; Socquet, Anne and Lasserre, Cécile. Large-scale InSAR monitoring of permafrost freeze-thaw cycles on the Tibetan Plateau: Geophysical Research Letters, 44(2), p. 901-909, illus. incl. sketch map, 34 ref., January 28, 2017.

Multitemporal interferometric synthetic aperture radar (InSAR) observations are used to characterize spatial variations of the permafrost active layer and its temporal evolution in Northwestern Tibet. We develop a method to enhance InSAR performances for such difficult terrain conditions and construct an 8 year timeline of the surface deformation over a 60,000 km² area. The ground movement induced by the active layer's response to climate forcing is limited to Cenozoic sedimentary basins and is spatially variable in both its seasonal amplitude (2.5-12 mm) and multiannual trend (-2 to 3 mm/yr). A degree-day integrated model adjusted to the data indicates that subsidence occurs when the surface temperature exceeds zero (May to October) over areas where seasonal movements are large (>8 mm). The period of subsidence is delayed by 1-2 months over areas where smaller seasonal movements are observed, suggesting an unsaturated soil where water occurs in the deeper part of the active layer. Abstract Copyright (2017), . American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2016GL070781

2018012140 Elvert, Marcus (University of Bremen, Center for Marine Environmental Sciences, Bremen, Germany); Pohlman, John W.; Becker, Kevin W.; Gaglioti, Benjamin; Hinrichs, Kai-Uwe and Wooller, Matthew J. Methane turnover and environmental change from Holocene lipid biomarker records in a thermokarst lake in Arctic Alaska: Holocene, 26(11), p. 1766-1777, illus. incl. 4 tables, 83 ref., November 1, 2016.

Arctic lakes and wetlands contribute a substantial amount of methane to the contemporary atmosphere, yet profound knowledge gaps remain regarding the intensity and climatic control of past methane emissions from this source. In this study, we reconstruct methane turnover and environmental conditions, including estimates of mean annual and summer temperature, from a thermokarst lake (Lake Qalluuraq) on the Arctic Coastal Plain of northern Alaska for the Holocene by using source-specific lipid biomarkers preserved in a radiocarbon-dated sediment core. Our results document a more prominent role for methane in the carbon cycle when the lake basin was an emergent fen habitat between ~12,300 and ~10,000 cal yr BP, a time period closely coinciding with the Holocene Thermal Maximum (HTM) in North Alaska. Enhanced methane turnover was stimulated by relatively warm temperatures, increased moisture, nutrient supply, and primary productivity. After ~10,000 cal yr BP, a thermokarst lake with abundant submerged mosses evolved, and through the mid-Holocene temperatures were approximately 3°C cooler. Under these conditions, organic matter decomposition was attenuated, which facilitated the accumulation of submerged mosses within a shallower Lake Qalluuraq. Reduced methane assimilation into biomass during the mid-Holocene suggests that thermokarst lakes are carbon sinks during cold periods. In the late-Holocene from ~2700 cal yr BP to the most recent time, however, temperatures and carbon deposition rose and methane oxidation intensified, indicating that more rapid organic matter decomposition and enhanced methane production could amplify climate feedback via potential methane emissions in the future.

DOI: 10.1177/0959683616645942

2018017653 Banville, David Roy (Université Laval, Département de Géologie et de Génie Géologique, Quebec, QC, Canada); Fortier, Richard and Dupuis, Christian. Objective interpretation of induced polarization tomography using a quantitative approach for the investigation of periglacial environments: Journal of Applied Geophysics, 130, p. 218-233, illus. incl. sects., 2 tables, geol. sketch map, 49 ref., July 2016.

The objective interpretation of induced polarization tomography for applications in periglacial environments is sometimes challenging using smoothness-regularized least square inversion because strong resistivity contrasts are often present. Ambiguities arise from the regularization process which smooths the contrast between layers and from artifacts created by the inversion. In periglacial environments, where frozen and thawed ground can coexist with large resistivity contrasts, such artefacts are often found in the models of electrical resistivity. To assess reliable cryohydrogeological models from the inversion of induced polarization tomography, quantitative interpretation criteria are needed. The present work describes a methodology based on forward-inverse modeling to build a cryohydrogeological model from induced polarization data and prior information using the resistivity and chargeability gradients to map transitions between adjacent layers. This methodology is tested on field-data acquired over a coarse grained aquifer within a glaciomarine deposit and ice-rich permafrost mounds within marine sediments. Delineation of the permafrost base is achieved despite the presence of an inversion artefact. The results of the interpretation are used to further constrain the inversion in order to map the ice-content based on the resistivity model and an empirical relationship. The proposed methodology provides a way to extract quantitative information even in difficult environmental settings.

DOI: 10.1016/j.jappgeo.2016.04.019

2018012044 Grosse, Guido (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Potsdam, Germany); Goetz, Scott J.; McGuire, A. David; Romanovsky, Vladimir E. and Schuur, Edward A. G. Changing permafrost in a warming world and feedbacks to the Earth system: Environmental Research Letters, 11(4), Paper no. 040201, 1 table, sketch map, 48 ref., April 2016.

The permafrost component of the cryosphere is changing dramatically, but the permafrost region is not well monitored and the consequences of change are not well understood. Changing permafrost interacts with ecosystems and climate on various spatial and temporal scales. The feedbacks resulting from these interactions range from local impacts on topography, hydrology, and biology to complex influences on global scale biogeochemical cycling. This review contributes to this focus issue by synthesizing its 28 multidisciplinary studies which provide field evidence, remote sensing observations, and modeling results on various scales. We synthesize study results from a diverse range of permafrost landscapes and ecosystems by reporting key observations and modeling outcomes for permafrost thaw dynamics, identifying feedbacks between permafrost and ecosystem processes, and highlighting biogeochemical feedbacks from permafrost thaw. We complete our synthesis by discussing the progress made, stressing remaining challenges and knowledge gaps, and providing an outlook on future needs and research opportunities in the study of permafrost-ecosystem-climate interactions. Copyright (Copyright) 2016 IOP Publishing Ltd

DOI: 10.1088/1748-9326/11/4/040201

2018012045 Kharuk, Viacheslav I. (Sukachev Forest Institute, Krasnoyarsk, Russian Federation); Shushpanov, Alexandr S.; Im, Sergei T. and Ranson, Kenneth J. Climate-induced landsliding within the larch dominant permafrost zone of central Siberia: Environmental Research Letters, 11(4), Paper no. 045004, illus. incl. 3 tables, sketch map, 42 ref., April 2016. Includes appendix.

Climate impact on landslide occurrence and spatial patterns were analyzed within the larch-dominant communities associated with continuous permafrost areas of central Siberia. We used high resolution satellite imagery (i.e. QuickBird, WorldView) to identify landslide scars over an area of 62 000 km². Landslide occurrence was analyzed with respect to climate variables (air temperature, precipitation, drought index SPEI), and Gravity Recovery and Climate Experiment satellite derived equivalent of water thickness anomalies (EWTA). Landslides were found only on southward facing slopes, and the occurrence of landslides increased exponentially with increasing slope steepness. Lengths of landslides correlated positively with slope steepness. The observed upper elevation limit of landslides tended to coincide with the tree line. Observations revealed landslides occurrence was also found to be strongly correlated with August precipitation (r=0.81) and drought index (r=0.7), with June-July-August soil water anomalies (i.e., EWTA, r=0.68-0.7), and number of thawing days (i.e., a number of days with t_max>0°C; r=0.67). A significant increase in the variance of soil water anomalies was observed, indicating that occurrence of landslides may increase even with a stable mean precipitation level. The key-findings of this study are (1) landslides occurrence increased within the permafrost zone of central Siberia in the beginning of the 21st century; (2) the main cause of increased landslides occurrence are extremes in precipitation and soil water anomalies; and (3) landslides occurrence are strongly dependent on relief features such as southward facing steep slopes. Copyright (Copyright) 2016 IOP Publishing Ltd

DOI: 10.1088/1748-9326/11/4/045004

2018011806 Abbott, Benjamin W. (Université de Rennes I, Observatoire des Sciences de l'Univers, Rennes, France); Jones, Jeremy B.; Schuur, Edward A. G.; Chapin, F. Stuart, III; Bowden, William B.; Bret-Harte, M. Syndonia; Epstein, Howard E.; Flannigan, Michael D.; Harms, Tamara K.; Hollingsworth, Teresa N.; Mack, Michelle C.; McGuire, A. David; Natali, Susan M.; Rocha, Adrian V.; Tank, Suzanne E.; Turetsky, Merritt R.; Vonk, Jorien E.; Wickland, Kimberly P.; Aiken, George R.; Alexander, Heather D.; Amon, Rainer M. W.; Benscoter, Brian W.; Bergeron, Yves; Bishop, Kevin; Blarquez, Olivier; Bond-Lamberty, Ben; Breen, Amy L.; Buffam, Ishi; Cai Yihua; Carcaillet, Christopher; Carey, Sean K.; Chen, Jing M.; Chen, Han Y. H.; Christensen, Torben R.; Cooper, Lee W.; Cornelissen, J. Hans C.; de Groot, William J.; DeLuca, Thomas H.; Dorrepaal, Ellen; Fetcher, Ned; Finlay, Jacques C.; Forbes, Bruce C.; French, Nancy H. F.; Gauthier, Sylvie; Girardin, Martin P.; Goetz, Scott J.; Goldammer, Johann G.; Gough, Laura; Grogan, Paul; Guo, Laodong; Higuera, Philip E.; Hinzman, Larry; Hu, Feng Sheng; Hugelius, Gustaf; Jafarov, Elchin E.; Jandt, Randi; Johnstone, Jill F.; Karlsson, Jan; Kasischke, Eric S.; Kattner, Gerhard; Kelly, Ryan; Keuper, Frida; Kling, George W.; Kortelainen, Pirkko; Kouki, Jari; Kuhry, Peter; Laudon, Hjalmar; Laurion, Isabelle; Macdonald, Robie W.; Mann, Paul J.; Martikainen, Pertti J.; McClelland, James W.; Molau, Ulf; Oberbauer, Steven F.; Olefeldt, David; Paré, David; Parisien, Marc-André; Payette, Serge; Peng, Changhui; Pokrovsky, Oleg S.; Rastetter, Edward B.; Raymond, Peter A.; Raynolds, Martha K.; Rein, Guillermo; Reynolds, James F.; Robards, Martin; Rogers, Brendan M.; Schädel, Christina; Schaefer, Kevin; Schmidt, Inger K.; Shvidenko, Anatoly; Sky, Jasper; Spencer, Robert G. M.; Starr, Gregory; Striegl, Robert G.; Teisserenc, Roman; Tranvik, Lars J.; Virtanen, Tarmo; Welker, Jeffrey M. and Zimov, Sergei. Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire; an expert assessment: Environmental Research Letters, 11(3), Paper no. 034014, illus. incl. 3 tables, 86 ref., March 2016.

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced. Copyright (Copyright) 2016 IOP Publishing Ltd

DOI: 10.1088/1748-9326/11/3/034014

2018011819 Pavlova, N. A. (Russian Academy of Sciences, Melnikov Permafrost Institute, Siberian Branch, Yakutsk, Russian Federation); Kolesnikov, A. B.; Efremov, V. S. and Shepelev, V. V. Groundwater chemistry in intrapermafrost taliks in central Yakutia: Water Resources, 43(2), p. 353-363, illus. incl. 2 tables, sketch map, 19 ref., March 2016. Original Russian Text: Pavlova, N. A., Kolesnikov, A. B., Efremov, V. S., Shepelev, V. V., published in Vodnye Resursy, Vol. 43, No. 2, p. 216-227, 1016.

An intrapermafrost aquifer system, which is widespread in the sand deposits of bestyakhskaya terrace of the Lena R. (Central Yakutia), is characterized by generalized data of many-year studies of its groundwater chemistry. The groundwater discharges onto land surface through high-yield springs. The largest such source forms the Ulakhan-Taryn Creek with a mean many-year yield of 20 740 m³/day. The results of generalization were used to show the chemistry of intrapermafrost water to be stable at both many-year and annual scales, to characterize the hydraulic interaction of intrapermafrost water with suprapermafrost and subpermafrost water, to assess the spatial variations of groundwater resources in the intrapermafrost aquifer from the head-formation to the discharge domain. The results of the study are of importance for solving the problem of centralized drinking water supply to large populated localities in the Central Yakutia, including Yakutsk City. Copyright 2016 Pleiades Publishing, Ltd.

DOI: 10.1134/S0097807816020135

2018011807 Segal, Rebecca A. (University of Victoria, School of Environmental Studies, Victoria, BC, Canada); Lantz, Trevor C. and Kokelj, Steven V. Acceleration of thaw slump activity in glaciated landscapes of the Western Canadian Arctic: Environmental Research Letters, 11(3), Paper no. 034025, illus. incl. 2 tables, sketch map, 79 ref., March 2016.

Climate change is increasing the frequency and intensity of thermokarst, but the influences of regional climate and physiography remain poorly understood. Retrogressive thaw slumping is one of the most dynamic forms of thermokarst and affects many areas of glaciated terrain across northwestern Canada. In this study, we used airphotos and satellite imagery to investigate the influence of climate and landscape factors on thaw slump dynamics. We assessed slump size, density, and growth rates in four regions of ice-rich terrain with contrasting climate and physiographic conditions: the Jesse Moraine, the Tuktoyaktuk Coastlands, the Bluenose Moraine, and the Peel Plateau. Observed increases in: (1) the area impacted by slumps (+2 to +407%), (2) average slump sizes (+0.31 to +1.82 ha), and (3) slump growth rates (+169 to +465 m² yr^-1) showed that thermokarst activity is rapidly accelerating in ice-rich morainal landscapes in the western Canadian Arctic, where slumping has become a dominant driver of geomorphic change. Differences in slump characteristics among regions indicate that slump development is strongly influenced by topography, ground ice conditions, and Quaternary history. Observed increases in slump activity occurred in conjunction with increases in air temperature and precipitation, but variation in slump activity among the four regions suggests that increased precipitation has been an important driver of change. Our observation that the most rapid intensification of slump activity occurred in the coldest environment (the Jesse Moraine on Banks Island) indicates that ice-cored landscapes in cold permafrost environments are highly vulnerable to climate change. Copyright (Copyright) 2016 IOP Publishing Ltd

DOI: 10.1088/1748-9326/11/3/034025

2018015096 Hou Yandong (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Wu Qingbai; Liu Yongzhi; Zhang Zhongqiong and Gao Siru. The thermal effect of strengthening measures in an insulated embankment in a permafrost region: Cold Regions Science and Technology, 116, p. 49-55, illus. incl. 5 tables, sketch map, August 2015. Based on Publisher-supplied data.

An embankment with heat insulation can only retard a rise in temperature or the thawing of permafrost, and the thermal stability of the embankment cannot be maintained under global warming conditions. Therefore, strengthening measures are required to ensure embankment stability. Based on in-situ observational data from the Qinghai-Xizang Railway in Beiluhe, variations in the thermal regime under a thermally insulated embankment after the implementation of strengthening measures were analysed. The results show that the strengthening measure of thermosyphon installation can play an effective role in the embankment cooling process; however, no protective effect of the spall rock revetment was observed. The shallow mean annual maximum temperature in the upper 0.5 m of soil decreased from 2.2 to 0 °C with an average of 1.8 °C, appearing as a striking "cold energy accumulation" process which predominantly results from thermosyphons and heat insulation material, after the strengthening measures were implemented. Meanwhile, the permafrost table under the embankment appeared as a "second rising process", ranging from 0.90 m for DK1139 + 670 to 2.56 m for DK1139 + 780, with an average of 1.66 m. The "sunny-shady slope effect" was not well controlled after the implementation of the strengthening measures under the embankment with thermal insulation. However, the difference in temperature between the ground and underlying permafrost table, under the left and right shoulder of the embankment, gradually decreased. Besides, thermal influence of the embankment to the surrounding permafrost in the deep layer is observed to be eliminated after the implementation of the strengthening measures. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.coldregions.2015.04.003

2018015083 Yu Fan (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Qi Jilin; Yao Xiaoliang and Liu Yongzhi. Comparison of permafrost degradation under natural ground surfaces and embankments of the Qinghai-Tibet Highway: Cold Regions Science and Technology, 114, p. 1-8, illus., June 2015. Based on Publisher-supplied data.

Permafrost under road embankments often degrades more seriously than that under natural ground surfaces due to the influences of both climate warming and road embankment. In a companion paper, we analyzed the states of permafrost degradation under road embankments in the five typical regions along the Qinghai-Tibet Highway (Yu et al., 2013a). In this paper, the states of permafrost degradation under natural ground surfaces, near the road embankments, are analyzed based on up to 15 years of in-situ geothermal data, while that under road embankments are also further analyzed. On this basis, the states of permafrost degradation and related processes are compared between the natural ground surfaces and road embankments. Possible influences of climate warming and road embankment on permafrost degradation are discussed. The results show different characteristics of permafrost degradation under natural ground surfaces and road embankments. The contributions of climate warming and road embankment on the thermal regime of permafrost may vary during the process of permafrost degradation. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.coldregions.2015.02.002

2018015138 Beck, I. (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Potsdam, Germany); Ludwig, R.; Bernier, M.; Strozzi, T. and Boike, J. Vertical movements of frost mounds in subarctic permafrost regions analyzed using geodetic survey and satellite interferometry: Earth Surface Dynamics, 3(3), p. 409-421, illus. incl. 4 tables, sketch maps, 70 ref., 2015.

Permafrost-affected soils cover about 40-45% of Canada. The environment in such areas, especially those located within the discontinuous permafrost zone, has been impacted more than any other by recorded climatic changes. A number of changes, such as surface subsidence and the degradation of frost mounds due to permafrost thawing, have already been observed at many locations. We surveyed three frost mounds (lithalsas) in the subarctic, close to Umiujaq in northern Quebec, using high-precision differential global positioning system (d-GPS) technology during field visits in 2009, 2010 and 2011, thus obtaining detailed information on their responses to the freezing and thawing that occur during the course of the annual temperature cycle. Seasonal pulsations were detected in the frost mounds, and these responses were shown to vary with their state of degradation and the land cover. The most degraded lithalsa showed a maximum amplitude of vertical movement (either up or down) between winter (freezing) and summer (thawing) of 0.19 ± 0.09 m over the study period, while for the least degraded lithalsa this figure was far greater (1.24 ± 0.47 m). Records from areas with little or no vegetation showed far less average vertical movement over the study period (0.17 ± 0.03 m) than those with prostrate shrubs (0.56 ± 0.02 m), suggesting an influence from the land cover. A differential interferometric synthetic aperture radar (D-InSAR) analysis was also completed over the lithalsas using selected TerraSAR-X images acquired from April to October 2009 and from March to October 2010, with a repeat cycle of 11 days. Interferograms with baselines shorter than 200 m were computed revealing a generally very low interferometric coherence, restricting the quantification of vertical movements of the lithalsas. Vertical surface movements of the order of a few centimeters were recorded in the vicinity of Umiujaq.

URL: http://www.earth-surf-dynam.net/3/409/2015/esurf-3-409-2015.pdf

2018009728 Sun Guangyou (Jilin University, Changchun, China). A re-examination of the tundra of the Tibetan Plateau; determination of geographic polarity for the third pole of Earth: Diqiu Kexue yu Huanjing Xuebao = Journal of Earth Sciences and Environment, 35(3), p. 97-105, (Chinese) (English sum.), illus. incl. 4 tables, sketch map, 40 ref., September 2013.

Understanding the tundra of the Tibetan Plateau is important for defining Earth's third pole (height) as geographic, creating a basic problem for global geographic science. A definition of tundra is proposed, as well as an index for a tundra environment consisting of five factors. The five factors are: mean July temperature is 0°C-10°C; a periglacial environment located in ice cover or on a glacier's periphery, with significant frost; permafrost is present; the soil has frost; and there are no trees. The region with average July temperatures of 0°C-10°C is about 50.4% (129.64´10⁴ km²) of the Tibetan Plateau; there is a wide distribution of valley glaciers, and a modern periglacial environment is typical for the region; the region's permafrost area is 72.05% of the Tibetan Plateau, where frozen soil and tundra soil have developed; and the area is treeless as the altitude is above the tree line, though there is small brush, grass, and moss. Therefore, there is a tundra environment on the Tibetan Plateau. Many plants in marshes are unique; when a wide frost peat mound combines with cellular soil, marsh tundra develops. Hill tundra develops around the plateau, and a plateau tundra developed in the middle. The Tibetan Plateau is characteristically highland, so there is no distinct highland tundra and it reflects the tundra diversity. It is incorrect to state that tundra only exists in China's Changbai Mountains, Altai Mountains, and Tien Shan; however, the Tibetan Plateau is the southern edge of China's tundra. The discovery of tundra on the Tibetan Plateau can confirm the geographic polarity for Earth's third pole, and has important significance for a deeper understanding of the plateau environment.

2018014741 Drozdov, A. V. (Alrosa, Institut Yakutniproalmaz, Yakutsk, Russian Federation) and Popov, V. F. Formirovaniye podzemnykh rezervuarov v kriolitozone Sibirskoy platformy, prigodnykh dlya udaleniya zhidkikh toksichnykh otkhodov [Developing underground reservoirs suitable for the storage of liquid toxic waste in the permafrost zone of the Siberian Platform]: Otechestvennaya Geologiya, 2013(2), p. 57-62 (English sum.), illus. incl. sketch map, 8 ref., April 2013.

This paper covers paleoclimatic and structural-tectonic conditions of forming favorable cryohydrogeological structures (underground reservoirs) for burying industrial effluents at the Siberian Platform. Basic capacity of natural reservoirs for industrial effluents pumping in is confined to regional tectonic disturbed intervals of the cryolithozone, which possess increased filtering-capacitance features of ores.

2018010008 Neradovskiy, L. G. K voprosu o stokhasticheskoy prirode signalov georadiolokatsii [Stochastic nature of ground-penetrating radar signals]: Geofizika (Moscow), 2013(2), p. 58-62 (English sum.), 3 ref., 2013. Based on Publisher-supplied data.

Based on the use of various GPR systems in the Yakutian permafrost region, this study has demonstrated that ground penetrating radar signals are of stochastic nature. This fact should be taken into account during data acquisition and processing stages, considering single GPR signal records as special samples from the ensemble of signals in the random process generating a field of various radio reflections from flat interfaces and irregularities in the soil and rock masses. Such an approach allows the use of one-time GPR signal records in determining the geometry of interfaces in horizontally layered sections, as is the common case in GPR practice. However, in studies of the structure of complex sections, as well as the state and properties of soils and rocks, especially those in frozen condition, one-time GPR signal records are fundamentally incapable of providing reliable interpretations and hence trustworthy results.

URL: http://geofdb.com/?id=article&val=201

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2018013283 Solomatin, V. I. Fizika i geografiya podzemnogo oledeneniya; uchebnoye posobiye dlya vuzov [Physics and geography of ground ice; a college textbook]: Geo, Novosibirsk, Russian Federation, 346 p. (English sum.), illus. incl. 21 tables, sects., sketch maps, 273 ref., 2013. ISBN: 9785906284358.

The most crucial materials and ideas of the physical and spatiotemporal laws of underground ice formation and underground glaciation development, including the author's results of long-term field and laboratory investigations, are collected, analyzed, and generalized. Theoretical and experimental studies of the physical processes of ice formation in the permafrost zone are used as a base for structural reconstructions of the thermal, facies and other conditions and of the factors responsible for different genetic types of underground ice. The most important result of the author's investigations is the theory of buried glacial ice in the permafrost zone, which fundamentally changes the understanding of the structure and paleogeography of underground glaciation, as well as its place in the Earth's cryosphere. A consequent analysis of the natural and experimental data on all scales and for all structural levels of underground ice formation (from the microworld of water phase transitions to the macroworld of the spatial and temporal evolution of geologic and geographic modifications of underground glaciation) permits the development of a genetic classification of underground ice and a general pattern of the zonal-climatic structure of underground glaciation.

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2018013913 Bandler, Aaron J. Geophysical constraints on critical zone architecture and subsurface hydrology of opposing montane hillslopes: 48 p., illus. incl. 3 tables, geol. sketch maps, 70 ref., Master's, 2016, Colorado School of Mines, Golden, CO. Includes appendices.

We investigate the relationship between slope aspect, subsurface hydrology, and critical zone (CZ) structure in a montane watershed by examining the orientations of foliation and fracturing and thicknesses of weathered material on north- and south-facing aspects. Weathering models predict that north-facing slopes will have thicker and more porous saprolite due to colder, wetter conditions, which exacerbate frost damage and weathering along open fractures. Using borehole imaging and seismic refraction, we compare the seismic velocity and anisotropy of north- and south-facing slopes with the orientation of fracturing. Fracturing occurs in the same dominant orientations across slopes, but the north-facing slope has more developed and slightly thicker soil as predicted, while the south-facing slope has thicker and more intact saprolite that is highly anisotropic in the direction of fracturing. Our data support hypotheses that subsurface flow is matrix-driven on north-facing slopes and preferential on south-facing slopes. We attribute thicker saprolite on south-facing slopes to heterogeneity induced by competition between infiltration, topographic stress, and permafrost during Pleistocene glaciation. We provide new constraints on subsurface architecture to inform future models of CZ evolution.

URL: http://hdl.handle.net/11124/170251

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2018012823 Abakumov, Evgeny (Saint-Petersburg State University, Biology and Soil Science, Applied Ecology, Saint-Petersburg, Russian Federation). Stabilization of polar soils organic matter; insights from 13-C NMR and ESR spectroscopy [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-2141, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Polar soils play a key role in the global carbon balance, as they contain maximum stocks of soil organic matter (SOM) within the whole pedosphere. Low temperature and severe conditions provides the accumulation of large amounts of organic matter in permafrost soils over thousands of years. The quality and composition of organic matter of polar soils is underestimated. In order to better understand the implication of permafrost SOM to greenhouse gas emissions, an accurate knowledge of its spatial distribution, both in terms of quantity and quality (i.e. biodegradability, chemical composition and humification degree) is needed. The chemical composition of SOM determines its decomposability and, therefore, it determines the rate at which carbon may be transferred from soils to the atmosphere under warming conditions. Biodegradability of SOM has been related to humification degree, as more advanced stages in the humification process imply a depletion of the labile molecules, as well as an increase in the bulk aromaticity, which provides a higher stability of the SOM. Soils from Antarctic and different sectors of Arctic biome were investigated by 13-C NMR and electron spin resonance spectroscopy. It was shown, that the characteristic feature of polar soils humic acids is the dominance of aliphatic compounds on the aromatic one. This is related to the humification precursors component composition, namely to dominance of the remnants of lower plants, especially in Antarctic and low period of biological activity, which regulates the humification rate. Humic acids of Antarctic and various Arctic soils show the portion of aromatic components not more than 30%. ESR spectroscopy shown that the concentration of free radicals is proportional to the humic acids stabilization degree. Less humified organic materials show the highest portion of free radical content, while the most developed soils and buried organic layers show decreased contents of free radicals. The database on soil organic matter composition of polar soil should be created with aim to evaluate current state of the humosphere and to provide the prognostic scenarios of possible mineralisation of humus. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-2141.pdf

2018012705 Ashastina, Kseniia (Senckenberg Research Institute, Station of Quaternary Palaeontology, Weimar, Germany); Kienast, Frank; Römermann, Christine; Kuzmina, Svetlana; Diekmann, Bernhard and Schirrmeister, Lutz. The Batagay permafrost mega thaw slump; an environmental archive of the Late Pleistocene continental climate [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-959, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Palaeoenvironmental data preserved in permafrost contribute in our understanding of climate changes and their influence on the biocenoses during the Late Quaternary. Here we present cryolithological and palaeoecological results of studies carried out on a newly described permafrost exposure near Batagay about 50 km from Verkhoyansk, Sakha Republic, Russia, the town with the most continental climate recorded in the northern hemisphere. According to Gunther et al. (2015), this unique exposure is the biggest mega thaw slump measured so far with the dimensions 800 m wide and 73 m deep. Only sparse data on the exposure are so far published in few articles (Novgorodov et al., 2013; Kunitsky et al., 2013; Ashastina et al., in press; Murton et al., 2016). The site is situated in West Beringia, the Late Quaternary landmass covered by tundra steppe and inhabited by diverse mega herbivores. We analyzed sedimentological data, plant macro- and micro-fossils together with insect remains in order to reconstruct the changes in the biome. The temporal frame for the accumulation of the sequence is provided by radiocarbon and optical stimulated luminescence dating, according to which the formation of the sequence started in the late Middle Quaternary. The features of permafrost accumulation and sedimentation give us an opportunity to propose the landscape changes responding to the climatic pulses of Pleistocene at this particular place. The shifts in vegetation from taiga to steppe associations are in a line with stadial and interstadial events. We propose a scheme of permafrost state and vegetation changes and merge it with climate variation during Late Quaternary. Ashastina, K., Schirrmeister, L., Fuchs, M., Kienast, F.: Pleistocene climate characteristics in the most continental part of the northern hemisphere: insights from cryolithological features of the Batagay mega thaw slump in the Siberian Yana Highlands. Climate of the Past, in press. doi:10.5194/cp-2016-84. Gunther, F., Grosse, G., Wetterich, S., Jones, B. M., Kunitsky, V. V., Kienast, F. and Schirrmeister, L.: The Batagay mega thaw slump, Yana Uplands, Yakutia, Russia: Permafrost thaw dynamics on decadal time scale. Abstract, Past Gateways, III international Conference and Workshop, 18-22 May 2015, Potsdam, Germany, 2015. Kunitsky, V. V., Syromyatnikov, I. I., Schirrmeister, L., Skachkov, Yu. B., Grosse, G., Wetterich, S. and Grigoriev, M. N.: Ice-rich and thermal denudation in the Batagay area (Yana upland, East Siberia), KriospheraZemli, XVII, No. 1, 56-68 (in Russian), 2013. Novgorodov, G. P., Grigorev, S. E., and Cheprasov, M. Y.: Prospective location of the mammoth fauna in the River Basin Yana, International journal of applied and fundamental research 8, 2013. Murton, J. B., Edwards, M. E., Lozhkin, A. V., Anderson, P. M., Bakulina, N., Bondarenko, O. V., Cherepanova, M., Danilov, P. P., Boeskorov V., Goslar T., Gubin, S. V., Korzun, J., Lupachev, A. V., Savvinov, G. N., Tikhonov, A., Tsygankova, V. I., and Zanina, O. G.: Reconnaissance palaeoenvironmental study of 90 m of permafrost deposits at Batagaika megaslump, Yana Highlands, northern Siberia, XI. ICOP, Potsdam, Germany, 20-24 June, 2016. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-959.pdf

2018012724 Elagina, Nelly (Russian Academy of Sciences, Institute of Geography, Department of Glaciology, Moscow, Russian Federation); Kutuzov, Stanislav; Chernov, Robert; Lavrentiev, Ivan; Vasilyeva, Tatiana; Mavlyudov, Bulat and Kudikov, Arseny. Establishing mass balance observation at Austre Gronfjordbreen, Nordenskjold land, Svalbard [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1005, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

The Arctic archipelago Svalbard consists of a vast glacierized area which contributes significantly to the sea level rise outside of Greenland and Antarctica due to recent warming. The glaciers of Svalbard have already experienced an unprecedented increase in average summer temperatures, melt periods, and rainfall in late autumn and early summer. Glaciers of the Nordenskjold land were the subject of glaciological studies conducted through the Soviet scientific program at the Institute of Geography RAS, Moscow starting in the 1960s. However, with the collapse of the Soviet Union glaciological monitoring was stopped in the late 1980s. It was resumed in 2003 with direct observations of winter accumulation and summer melt at a number of glaciers in Nordenskjold land. However, until now snow pit and stake data were inconsistent and were reported randomly. Recent efforts by the Institute of Geography RAS have been aimed at establishing mass balance observation at Austre Gronfjordbreen (7 km2) located 16 km south of Barentsburg. Starting from 2014 observations have included a new ablation stake network of 15 stakes measured biannually, two automatic weather stations located at the glacier tongue and at the accumulation area, and annual high resolution GPR surveys of snow thickness together with snow pit measurements repeated every spring. Special attention has been paid to the evaluation of refreezing ice and superimposed ice distribution. Active layer (10 m) borehole temperatures are measured annually at stake locations. The obtained mass balance gradients are compared with the geodetic mass balance changes in 1990-2005 and recent Arctic DEM data. Additionally glacier bedrock, polythermal structure and surface topography maps have been completed using GPR data and DGPS measurements. All available satellite imagery has been used to reconstruct the snowline elevation changes from 1986 to 2016. Remarkably almost a total absence of accumulation area has been registered in recent years. Current plans are to apply a spatially distributed mass balance model to seasonal mass balance surveys. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1005.pdf

2018014161 Evgrafova, Alevtina (University of Koblenz-Landau, Geography Department, Koblenz, Germany); Kühnel, Anna; Bogner, Christina; Haase, Ina; Shibistova, Olga; Guggenberger, Georg; Tananaev, Nikita; Sauheitl, Leopold and Spielvogel, Sandra. Visible-near infrared spectroscopy as a tool to improve mapping of soil properties [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract 851, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Spectroscopic measurements, which are non-destructive, precise and rapid, can be used to predict soil properties and help estimate the spatial variability of soil properties at the pedon scale. These estimations are required for quantifying soil properties with higher precision, identifying the changes in soil properties and ecosystem response to climate change as well as increasing the estimation accuracy of soil-related models. Our objectives were to (i) predict soil properties for nested samples (n=296) using the laboratory-based visible-near infrared (vis-NIR) spectra of air-dried (<2 mm) soil samples and values of measured soil properties for gridded samples (n=174) as calibration and validation sets; (ii) estimate the precision and predictive accuracy of an empirical spectral model using (a) our own spectral library and (b) the global spectral library; (iii) support the global spectral library with obtained vis-NIR spectral data on permafrost-affected soils. The soil samples were collected from three permafrost-affected soil profiles underlain by permafrost at various depths between 23 cm to 57.5 cm below the surface (Cryosols) and one soil profile with no presence of permafrost within the upper 100 cm layer (Cambisol) in order to characterize the spatial distribution and variability of soil properties. The gridded soil samples (n=174) were collected using an 80 cm wide grid with a mesh size of 10 cm on both axes. In addition, 300 nested soil samples were collected using a grid of 12 cm by 12 cm (25 samples per grid) from a hole of 1 cm in a diameter with a distance from the next sample of 1 cm. Due to a small amount of available soil material (<1.5 g), 296 nested soil samples were analyzed only using vis-NIR spectroscopy. The air-dried mineral gridded soil samples (n=174) were sieved through a 2-mm sieve and ground with an agate mortar prior to the elemental analysis. The soil organic carbon and total nitrogen concentrations (in %) were determined using a dry combustion method on the Vario EL cube analyzer (Elementar Analysensysteme GmbH, Germany). Inorganic C was removed from the mineral soil samples with pH values higher than 7 prior to the elemental analysis using the volatilization method (HCl, 6 hours). The pH of soil samples was measured in 0.01 M CaCl2 using a 1:2 soil:solution ratio. However, for soil sample with a high in organic matter content, a 1:10 ratio was applied. We also measured oxalate and dithionite extracted iron, aluminum and manganese oxides and hydroxides using inductively coupled plasma optical emission spectroscopy (Varian Vista MPX ICP-OES, Agilent Technologies, USA). We predicted the above-mentioned soil properties for all nested samples using partial least squares regression, which was performed using R program. We can conclude that vis-NIR spectroscopy can be used effectively in order to describe, estimate and further map the spatial patterns of soil properties using geostatistical methods. This research could also help to improve the global soil spectral library taking into account that only few previous applications of vis-NIR spectroscopy were conducted on permafrost-affected soils of Northern Siberia. Keywords: Visible-near infrared spectroscopy, vis-NIR, permafrost-affected soils, Siberia, partial least squares regression. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-851.pdf

2018016547 Fritz, Michael (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Periglacial Research, Potsdam, Germany) and Lantuit, Hugues. Collapsing permafrost coasts in the Arctic [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-3464, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Arctic warming is exposing permafrost coastlines, which account for 34% of the Earth's coasts, to rapid thaw and erosion. Coastal erosion rates as high as 25 m yr-1 together with the large amount of organic matter frozen in permafrost are resulting in an annual release of 14.0 Tg (1012 gram) particulate organic carbon into the nearshore zone. The nearshore zone is the primary recipient of higher fluxes of carbon and nutrients from thawing permafrost. We highlight the crucial role the nearshore zone plays in Arctic biogeochemical cycling, as here the fate of the released material is determined to: (1) degrade into greenhouse gases, (2) fuel marine primary production, (3) be buried in nearshore sediments or (4) be transported offshore. With Arctic warming, coastal erosion fluxes have the potential to increase by an order of magnitude until 2100. Such increases would result in drastic impacts on global carbon fluxes and their climate feedbacks, on nearshore food webs and on local communities, whose survival still relies on marine biological resources. Quantifying the potential impacts of increasing erosion on coastal ecosystems is crucial for food security of northern residents living in Arctic coastal communities. We need to know how the traditional hunting and fishing grounds might be impacted by high loads of sediment and nutrients released from eroding coasts, and to what extent coastal retreat will lead to a loss of natural habitat. Quantifying fluxes of organic carbon and nutrients is required, both in nearshore deposits and in the water column by sediment coring and systematic oceanographic monitoring. Ultimately, this will allow us to assess the transport and degradation pathways of sediment and organic matter derived from erosion. We need to follow the complete pathway, which is multi-directional including atmospheric release, lateral transport, transitional retention in the food web, and ultimate burial in seafloor sediments. We present numbers of multi-year dissolved organic matter (DOM) fluxes from coastal erosion into the nearshore zone of the southern Canadian Beaufort Sea. We further explore removal and degradation patterns of DOM based on oceanographic monitoring of coastal waters. Ultimately, we present accumulation rates and biogeochemical properties of marine sediment sequences drilled off the Yukon coast to track the pathways of the eroded material. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-3464.pdf

2018016209 Gries, Philipp (Eberhard Karls University Tübingen, Department of Geosciences, Soil Science and Geomorphology, Tubingen, Germany); Wagner, Julia; Kandolf, Lorenz; Henkner, Jessica; Kühn, Peter; Scholten, Thomas and Schmidt, Karsten. Investigations on soil organic carbon stocks and active layer thickness in West Greenland [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1304, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

The soil organic carbon (SOC) pool in the first 300 cm of arctic soils includes about 50% of the estimated global terrestrial below ground organic carbon, which makes about 1024 Pg C and up to 496 Pg within the upper permafrost one meter. Being a sensible ecosystem, the Arctic is sensitive to climate change. Hence, thawing of permafrost-affected soils to greater depth and for longer periods increases the release of CO₂ and CH₄ to the atmosphere, which queries soils as an important carbon pool. Especially in arctic environments, sparse soil data and limited knowledge of soil processes cause underestimation of SOC stocks. Due to different regional climatic conditions, changing soil-environmental conditions result in varying soil organic carbon contents in Greenland. In West Greenland, coastal oceanic conditions turn into continental climate at the ice margin showing less precipitation, higher insolation and increasing permafrost thickness. The objectives of this study are (i) to determine SOC stocks and active layer thickness (ALT), (ii) to identify main environmental factors influencing SOC stocks and ALT, and (iii) to specify differences of SOC stocks, ALT and influencing factors induced by a climatic trend in West Greenland. Respecting different climatic conditions, one study area is situated next to the ice margin in the Kangerlussuaq area and the second one is located near Sisimiut at the coast. Both study areas (2 km²) are representative for each region and have similar environmental settings. Soil samples were taken from depth increments (0-25, 25-50, 50-100, and 100-200 cm) at 80 sampling locations in each study area. Additionally, we addressed soil moisture content (TDR-measurements), ALT, and soil horizons, vegetation (types, coverage), and terrain characteristics (aspect, geomorphology) at each sampling point. As a preliminary result, at the coast the average SOC stock is 13.1 kg/m2 in the upper 25 cm and about 35.9 kg/m2 in the first 200 cm. The amount of SOC stocks is slightly connected to terrain with higher values at depressions and decreasing values upslope. We assume for the Sisimiut area that south (SE, S, SW) facing areas have high SOC stocks due to higher biomass production because of higher insolation. In both study areas, plant growth, aspect, and soil moisture affect the amount of ALT, which is low beneath dense and tall dwarf shrub vegetation on flat plains and depressions having high soil moisture contents. At north facing slopes, absence of direct insolation results in low ALT less than 14 cm at the Kangerlussuaq study area. Soil moisture content, ALT and occurrence of permafrost as well as vegetation type and coverage reflect the climatic trend from the coast to the ice margin in West Greenland. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1304.pdf

2018016480 Grzyb, Jaroslaw (Polish Academy of Sciences, Insitiute of Geophysics, Warsaw, Poland) and Majdanski, Mariusz. Seismic imaging of post glacial sediments; technical problems and solutions [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-3292, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Near surface seismic imaging of post glacial sediments is difficult, as standard methods hardly works. To recognize such complicated shallow structures it is necessary to acquire a high resolution data, and that leads to several technical problems. In this work we present how we solved the problem of precise time measurements for our seismic source based on GPS system, and how we improved performance of our seismic source. Our solution for timing is based on geodetic instrument and is used with a standard accelerated with drop (PEG-40) and a sledgehammer, but also with hydrophones in marine environment with chemical sources. This technology has been used in several field experiment of local and regional scale in Central Europe, but also in Arctic. In near future this technology will be used in permafrost study in Spitsbergen, and also with near-surface analysis with three component sources and receivers. We present initial results of our observations of horizontal component seismic source. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-3292.pdf

2018016066 Hrbacek, Filip (Masaryk University, Department of Geography, Brno, Czech Republic); Knazkova, Michaela; Nyvlt, Daniel; Laska, Kamil; Mueller, Carsten W. and Ondruch, Jakub. Monitoring of active layer thermal regime and depth on CALM-S site, James Ross Island, Eastern Antarctic Peninsula [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-707, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Active layer thickness and its dynamic are considered one of the key parameters of permafrost-affected ground. They variability are very sensitive to specific local conditions, especially climate, vegetation, snow cover or soil texture and moisture. To better understand the local variability of active layer thickness in Antarctica, the original Circumpolar Active Layer Monitoring protocol (CALM) was adapted as its southern form (CALM-S) with respect to specific conditions of Antarctica. To date, almost 40 CALM-S sites were registered across the Antarctic continent with the highest density on western Antarctic Peninsula (South Shetlands) and Victoria Land in East Antarctica (McMurdo region). On James Ross Island, CALM-S site was established in February 2014 as the first CALM-S in the eastern Antarctic Peninsula region. The CALM-S site is located near the Johann Gregor Mendel Station on the northern coast of James Ross Island. The area delimited to 80´ 70 m is elevated at 8 to 11 m asl. Geologically it consists of a Holocene marine terrace (~80% of CALM-S area) with typical sandy material and passes to lithified to poorly disintegrated sedimentary rocks of material and a typical bimodal composition. For both geologically different parts of CALM-S site, ground temperature was measured at two profiles at several levels up to 200 cm depth using resistance thermometers Pt100/8 (accuracy ± 0.15 °C). The air temperature at 2 m above surface was monitored at the automatic weather station near Johann Gregor Mendel Station using resistance thermometer Pt100/A (accuracy ± 0.15°C). Data used in this study were obtained during the period from 1 March 2013 to 6 February 2016. Mechanical probing of active layer depth was performed in 72 grid points at the end of January, or beginning of February in 2014 to 2016. During the whole study period, mean annual air temperature varied between -7.0°C (2013) and -6.7°C (2015), while the mean annual ground temperature at 5 cm ranged from -5.6 °C (2013) to -5.3 °C (2014). Thawing season started in mid-November between 17th (2013/14) and 24th (2014/15) and ended at the end of February (22nd in 2014/15) and beginning of March (7th in 2013/14). The maximum active layer thickness determined from 0°C isotherm varied from 86 to 87 cm at profile 1, while it reached only 51 to 65 cm at profile 2. The mean probed active layer depth varied between 66 cm (2013/4) and 78 cm (2014/15). The maximum probed active layer depth increased from 100 cm in 2014 to 113 cm in 2016. High variability of active layer depth across CALM-S site was caused by different ground thermal properties of Holocene marine terrace sand and Cretaceous clayey sandstones. These results differ significantly from another CALM-S sites in Antarctica, where the main factors affecting thawing depth variability were snow cover and topography. These results confirmed previous observation from James Ross Island, where variability of active layer depth was related primarily to different ground properties (texture, moisture, physical characteristic) then local climate or snow cover. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-707.pdf

2018016511 Khomutov, Artem (Russian Academy of Sciences, Siberian Branch, Earth Cryosphere Institute, Tyumen, Russian Federation); Leibman, Marina; Dvornikov, Yury and Aref'yev, Stanislav. Results of the first field visit to Antipayutinsky gas-emission crater (AntGEC) on Gydan Peninsula, Russia in 2016 [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-3371, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Deep craters in the North of West Siberia are specific objects in permafrost zone first observed in 2014 and later detected on satellite images to form in 2013. Their origin is under discussion yet. Authors hypothesize their formation from gas accumulation and later sudden emission. Scientific community was informed of Antipayutinskiy gas-emission crater (AntGEC) soon after first Yamal crater was found in 2014. Despite this knowledge, a real opportunity to visit AntGEC with true coordinates and logistic support appeared only in 2016 field campaign. Our field study of AntGEC included a description of the surrounding area and visible geological section, GPS-survey of GEC settings and related surface disturbances, measuring the depth of seasonal thaw, the internal lake bathymetry and water sampling from internal lake and other "knocked out" ponds. We also looked for traces of the initial mound preceding the GEC formation. We collected the willow branches for tree-ring dating of the events preceding the "eruption" using a specially developed technique, tested on willows, collected from Yamal gas-emission crater (GEC-1). Based on measurements of the depth, bathymetric map of AntGEC was compiled. The maximum measured depth at the crater center was 3.6 meters. Depth distribution was uniform in plan. The estimated volume of lake water was 1642.6 m3. Water samples were taken at different depths. The water temperature at the time of measurement was 8.8°C near the surface and 7.8°C at a depth of 3 meters. Preliminary dendrochronological analysis of AntGEC willow from the ejected block with turf showed the age of about 90 years. Annual growth rate of willow on AntGEC location was low ( 0.1 mm) in 1918-1947. An elevated growth rate (0.45 mm) is registered in 1948. This increase is chronologically correlated with previously defined increase of willow growth rate on first Yamal crater location. A significant difference between Gydan AntGEC and 3 known Yamal GEC is observed. While Yamal GECs are located on gentle concave slopes, overgrown with a more or less dense willow thickets, predominantly in loamy soils, the AntGEC is located almost on the watershed, although near the drainage hollow, in mostly sandy deposits, one of the walls exposes a hilltop sandy section, with windblown sandy depressions. Shrubs even in the bottom of the hollow form separate groups. Only tabular ground ice close to the surface unites Yamal and Gydan GECs. With these new data we need to adjust our understanding of landscape indicators of terrains potentially dangerous in relation to the GEC formation so far based on Yamal GEC study. This research is supported by Russian Science Foundation Grant 16-17-10203. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-3371.pdf

2018016079 Kramshoj, Magnus (University of Copenhagen, Department of Biology, Copenhagen, Denmark); Holst, Thomas; Albers, Christian; Holzinger, Robert; Elberling, Bo and Rinnan, Riikka. Microbial uptake of biogenic volatile organic compounds released from thawing permafrost [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-732, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Non-methane biogenic volatile organic compound (BVOC) emissions are one of the greatest uncertainties in our understanding of the climate system, and the scientific interest in this area has increased accordingly during the last decades. The focus of BVOC studies has been on vegetation emissions, but microorganisms themselves and decomposition of organic material also lead to significant BVOC production. Arctic areas are currently experiencing considerable climate warming, and the consequently thawing of permafrost soils expose vast amounts of organic material to decomposition. This event will undoubtedly have serious consequences for methane and carbon dioxide emissions, but the decomposition processes also present a potential source of BVOCs. However it may be that microorganisms in the uppermost active soil layers can utilize BVOCs as a carbon source similarly to methane. Our aim was to assess the following questions: 1) Are BVOCs released from the thawing permafrost, and what is the quantity and quality of the emissions? 2) Are the microorganisms in cold Arctic soils able to consume BVOCs rising from beneath thawing permafrost soil, and in that way hinder the BVOCs from reaching the atmosphere? In laboratory experiments measuring BVOC emissions, on a proton transfer reaction time of flight mass spectrometer (PTR-TOF-MS), in permafrost and active layer soils we elucidated the capacity of Arctic soils to serve as a sink and source for BVOCs. Thawing permafrost soils proved to be a significant source of a large range of BVOCs. However active layer soils proved to be an equally good sink, taking up the BVOCs released from the permafrost. Additional studies with 14C-labeled compounds were used to determine the ability of the soil microorganisms to mineralize a series of the most abundant BVOCs released from the permafrost [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-732.pdf

2018016116 Kula, Damian (University of Silesia, Katowice, Poland) and Olszewska, Dorota. Seasonal variability of horizontal to vertical spectral ratio in polar regions [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1071, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

The Horizontal to Vertical Spectral Ratio method is commonly used in engineering seismology as quick and easy to use tool for estimating resonant frequency of the ground. One of the method's features is its stability over time which allows to compare results calculated using data from different periods of time. This work is focused on checking stability of the HVSR method in arctic regions, where permafrost might occur. The permafrost is a phenomena that is commonly present in arctic regions and is described as a ground that's temperature is constantly below 0 degree Celsius for more than two years. When the permafrost is not covered with ice there also occurs phenomena called active layer of the permafrost which is an uppermost layer of the ground that freezes during winter season and thaws during summer season. By a geological methods the existence permafrost might be indicated only as existence of the ice in the geological realm. Due to that, for discrimination of depth of permafrost table there are commonly used methods that are sensitive to changes of resistivity or shear wave velocity in first few meters of the ground. In a previous work there were proven that results of the HVSR vary according to changes of depth of permafrost table which correlates well with changes of temperature of the ground down to 1 m. Results of inversion of the H/V curves well correlate with thickness of active layer estimated using Electrical Resistivity Tomography surveys. This work focuses on investigation of variability of horizontal to vertical spectral ratio in different regions of northern hemisphere where permafrost might be present. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1071.pdf

2018016246 Myshonkov, Alexander (Moscow State University, Soil Science Faculty, Moscow, Russian Federation); Matyshak, George and Petrzhik, Natalia. Cryogenic disturbance and its impact on soils of frost boil ecosystems of Taz peninsula, West Siberia [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1522, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

For the last years there is an active development of permafrost zone, which is about 60% of the territory of Russia. More than 15% of this area belong to different types of tundra. Frost boil ecosystems, the formation of which is associated with the cryogenesis and cryogenic disturbance processes are one of the most specific tundra landscape. Such landscape forms of tundra ecosystems cover the area over 68000 sq. km - 20% of total Russian tundra area. Cryogenic processes leading to the formation of patterned ground (such as frost boils, non-sorted circles, ice-wedge polygons) are important mechanisms, which control the landscape distribution of soil and phytomass carbon in continuous permafrost terrain. Frost boil ecosystem's properties have been poorly studied. So, the aim of this work is to explore the functioning parameters and properties of frost boil soils. The object - frost boil ecosystems, - is located in the southern tundra of Taz peninsula, about 150 km north from Novy Urengoy (57 28 050,600 N, 76 42 032,600 E). Frost boils are small (0,5-2 m diameter and 5-15 cm height), barren, non-sorted circles separated by completely vegetated (moss-lichens and shrubs) troughs - interboils. Our monitoring section (100 sq. m.) was set on a typical frost-boil landscape. Within this area we obtained moisture content and temperature of upper layer (0-10 cm), active layer depth, CO₂ flux. This analyzed site includes more than 40 frost boils. Measurements were made both on boil and interboil patches in 10-20 replicates. Samples were taken both from frost boils and interboils upper layers as well as from horizons two soil pit profiles. Different soil parameters were obtained by laboratory analysis: pH (1: 2,5), BR, SIR (Anderson, 1978), TC, DOC (Kalbitz, 2003). It is estimated that total area with frost boils is approx. twice larger than troughs area with vegetation cover within the monitoring site. The soil properties of frost boil and interboil are significantly different. Frost boils have lack of vegetation and, as consequence, no organic matter in uppers pit horizons. We find organic horizon in interboil areas - it can be up to 15 cm height. Frost boils have higher moisture and temperature levels: 25,6 ± 6 % and 12,5 ± 0,8 °C, as compared with interboil areas: 15 4 % and 8,5 ± 0,8 °C. Active layer is found on an average depth of 125 ± 5 cm under the frost boils to 110 ± 5 cm under the interboils. Chemical analysis shows that pH varies from neutral values at the bare spot (~ 6-6.2) to a slightly acidic at microdepressions (~ 5-5,3). These differences lead to the contrast in biological activity: CO₂ flux is higher in the troughs than in spots (193 and 55 mg*m²/hour, resp.). BR results are the same: it is higher in troughs than in spots more than 10 times. Cryogenic processes actively influence on the soil formation and redistribution of substances in studied ecosystems. These facts of influence should be considered in different calculations. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1522.pdf

2018012735 Nesterova, Natalia (St. Petersburg State University, Institute of Geosciences, Russian Federation); Makarieva, Olga and Lebedeva, Lyudmila. Hydrological modelling over different scales on the edge of the permafrost zone; approaching model realism based on experimentalists' knowledge [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1047, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Quantitative and qualitative experimentalists' data helps to advance both understanding of the runoff generation and modelling strategies. There is significant lack of such information for the dynamic and vulnerable cold regions. The aim of the study is to make use of historically collected experimental hydrological data for modelling poorly-gauged river basins on larger scales near the southern margin of the permafrost zone in Eastern Siberia. Experimental study site "Mogot" includes the Nelka river (30.8 km2) and its three tributaries with watersheds area from 2 to 5.8 km2. It is located in the upper elevated (500-1500 m a.s.l.) part of the Amur River basin. Mean annual temperature and precipitation are -7.5°C and 555 mm respectively. Top of the mountains with weak vegetation has well drained soil that prevents any water accumulation. Larch forest on the northern slopes has thick organic layer. It causes shallow active layer and relatively small subsurface water storage. Soil in the southern slopes has thinner organic layer and thaws up to 1.6 m depth. Flood plains are the wettest landscape with highest water storage capacity. Measured monthly evaporation varies from 9 to 100 mm through the year. Experimental data shows importance of air temperature and precipitation changes with the elevation. Their gradient was taken into account for hydrological simulations. Model parameterization was developed according to available quantitative and qualitative data in the Mogot station. The process-based hydrological Hydrograph model was used in the study. It explicitly describes hydrological processes in different permafrost environments. Flexibility of the Hydrograph model allows take advantage from the experimental data for model set-up. The model uses basic meteorological data as input. The level of model complexity is suitable for a remote, sparsely gauged region such as Southern Siberia as it allows for a priori assessment of the model parameters. Model simulation of river runoff, snow depth, soil temperature and moisture in the Mogot study site are satisfactory. Model parameterization developed on the Mogot watersheds was employed to simulate runoff generation in the four river basins with area from 150 to 4060 km2 in the surrounded region. We conclude that data about internal catchment processes is extremely helpful for the increasing model realism. Hard and soft experimental knowledge in the form of model parameters and settings could be transferred to larger river basins in the region. The study is supported by Russian Foundation for Basic Research (project 15-35-21146). [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1047.pdf

2018016165 Ogneva, Olga (Lomonosov Moscow State University, Department of Soil Science, Moscow, Russian Federation); Matyshak, George and Tarkhov, Matvey. Frozen peatlands; carbon store and the climate change [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1207, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Peatlands soils in the northern permafrost region store approximately 40% of total Earth's soils carbon. These soils develop under the influence of cryogenic processes especially such as freeze-thaw and cryoturbations. Climate change predictions suggest that the frequency of soil freeze-thaw cycles (FTCs) will increase in cool temperate and other high-latitude regions. This trend may cause a response in organic matter decomposition rate--that will result in significant changes of greenhouse gases emission (CO₂, CH₄). For further predictions improvement of soils response to global climate changes it is necessary to estimate the impact of FTCs in permafrost soils on organic matter decomposition. We investigated the effects of FTCs on microbial biomass, basal respiration, metabolic quotient and dissolved organic matter (DOM) content (carbon--DOC and nitrogen--DON) in frozen peatlands soils by laboratory modelling experiment. Frozen peatlands from the north of Western Siberia in Nadym area (N65 190, E72 530), in a zone of discontinuous permafrost were studied. The soil cover of these formations is represented by a complex of Typic Histoturbels (Turbic Cryosol) and Typic Historthels (Cryic Histosols). Peat profiles of both soil types were divided into horizons due to decomposition degree (from 15 to 55-60%), age (from 1000 to 5700 yrs) and botanic composition (oligotrophic, mesotrophic, eutrophic). During the experiment, first group of samples of peat horizons (field moisture content) were subjected for 10 times to 3-day FTCs at the temperature of -10 and +4°C. In the second group of peat samples were incubated at +4°C (with no freeze-thaw). It was established that all studied microbial properties were inversely proportional with decomposition degree of peat, except metabolic quotient. Our results illustrate that microbial activity, estimated by BR, shows resistance to FTCs and doesn't significantly differ after FTCs an average. Microbial biomass (carbon and nitrogen) as well as BR doesn't differ too. The most intensive response to FTCs shows DOM content value which was 1.5 times higher on average in samples after FTCs in comparison with control samples. We suppose that increase of FTs frequency in soil will result in significant acceleration mineralization of peat. Because these processes exert disruptive effects on soil organic matter, provide converting carbon from pool into forms available for microbial communities, thus involving stored carbon into the carbon turnover. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1207.pdf

2018016370 Olefeldt, David (University of Alberta, Renewable Resources, Edmonton, AB, Canada); Heffernan, William; Gibson, Carolyn; Burd, Katheryn and Estop-Aragones, Cristian. Interactive effects of wildfire and permafrost thaw on peatland carbon cycling [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-3032, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Boreal peatland complexes in western Canada are fine-scale mosaics of permafrost affected peat plateaus interspersed with Sphagnum dominated thermokarst bogs where permafrost is absent. Wildfire further affects landscape patterning of peatland complexes, where virtually all peat plateaus are in a stage of secondary succession following wildfire. With climate change we expect both permafrost thaw and wildfire activity to increase in these landscapes, and to have important impacts on carbon cycling. In a number of studies, we have used soil chamber techniques to assess the influence of both permafrost thaw and wildfire on soil respiration, net ecosystem exchange and methane emissions. We used chronosequences to assess the influence of time since both permafrost thaw (3 - 15 years) and wildfire (20 - 150 years). Radiocarbon signatures of soil respiration in both burned and thawed locations was used to determine the contribution of aged soil carbon to soil respiration. We furthermore characterized individual and interactive effects of fire and thaw on microbial and photochemical lability of dissolved organic matter. At many field sites it was clear that recent wildfire had accelerated permafrost thaw, and we combined field observations of soil thermal regimes with remote sensing approaches to assess the role of wildfire for accelerating permafrost thaw over the last 50 years at a regional scale. Overall, our results highlight the need to consider both individual and interacting effects of thaw and fire for projections of the future carbon cycling at the regional level. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-3032.pdf

2018016084 Orlov, Timofey (Russian Academy of Sciences, Sergeev Institute of Environmental Geoscience, Russian Federation); Sadkov, Sergey; Panchenko, Evgeniy and Zverev, Andrey. Stochastic modelling for lake thermokarst and peatland patterns in permafrost and near permafrost zones [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-743, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Peatlands occupy a significant share of the cryolithozone area. They are currently experiencing an intense affection by oil and gas field development, as well as by the construction of infrastructure. That poses the importance of the peatland studies, including those dealing with the forecast of peatland evolution. Basic model Earlier we conducted a similar probabilistic modelling for the areas of thermokarst development. Principle points of that were: 1. Appearance of a thermokarst depression within an area given is the random event which probability is directly proportional to the size of the area (Ds). For small sites the probability of one thermokarst depression to appear is much greater than that for several ones, i.e. p₁ = -gDs + o(Ds), p_k = -o(Ds) k = -2, 3. 2. Growth of a new thermokarst depression is a random variable independent on other depressions' growth. It happens due to thermoabrasion and, hence, is directly proportional to the amount of heat in the lake and is inversely proportional to the lateral surface area of the lake depression. By using this model, we are able to get analytically two main laws of the morphological pattern for lake thermokarst plains. First, the distribution of a number of thermokarst depressions (centers) at a random plot obey the Poisson law: P (k, s) = -(gs)^k/k! ´ e^-gs): where g is an average number of depressions per area unit, s is a square of a trial sites. Second, lognormal distribution of diameters of thermokarst lakes is true at any time, i.e. density distribution is given by the equation: f_d(x,t) - 1/²Ö2psc²Öt e^{-(ln x - at)2/2s2t} where a,s are distribution parameters, t is time since the process have started. Thermokarst development in peaty soils is normally accompanied by the formation of ridge-lake patterns. Ridge-hollow structures (RHS) possess a specific implication in a peatland functioning system. They are associated with the surface and underground water flows, as well as with the contemporary and buried relief. This makes reasonable the probabilistic modelling applied to the RHS. The probabilistic modelling here mainly implies the analysis of an area with the uniformly distributed patterns of RHS. The intersection points of the ridges are here considered as the specific points, describing the RHS pattern. For the model we picked the following several key parameters: average number of ridges and hollows along a linear profile, average width of ridges and hollows along a linear profile, number and spatial distribute of the ridge intersection points within an elementary block, average area of hollows, distribution of sizes of hollows, local and general curvature of the ridges. The former are the succeeding generation stage of ridge-hollow patterns. Therefore, in permafrost the transition from the ridge-hollow pattern to the ridge-lake one is a companion process to the process of thermokarst. Probabilistic behavior is typical of ridge-hollow structures. The hollow sizes follow the lognormal distribution. Ridge junction points' distribution has the Poisson behavior. Results Hence, the probabilistic modelling of ridge-hollow structures in cryolithozone can rely on the following parameters: hollow size, ridge size, spatial distribution of hollow centroids and ridge junction points. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-743.pdf

2018016268 Petrzhik, Nataliya (Moscow State University, Faculty of Soil Science, Russian Federation); Matyshak, George; Myshonkov, Alexander and Petrov, Dmitry. Arctic ecosystem reaction on permafrost melting as a result of 40 years anthropogenic impact [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1560, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Arctic ecosystems are sensitive indicators of environmental change. The increasing of anthropogenic impact perturb the natural ecosystems balance, first of all significant changes happen in soil and vegetation. It is necessary to study the permafrost ecosystem response, as the permafrost covers the quarter of the world and more than a half of Russia. Since 1960 the oil and gas industry grows in Russia. The hydrocarbons can be transferred by pipelines only in the heated state. The main effect of construction and operation of pipeline is the heating of soil and permafrost degradation. The goal of this study was to estimate the response of landscapes and permafrost ecosystem of north of West Siberia to the cumulative action of pipelines. The main objective was to investigate the warming impact on the properties and function of the soil along the pipelines in permafrost zone. The studied object was vegetation and soil cover of the north of Western Siberia ecosystems after the action of pipelines. The areas with maximum effect of heat lines were selected by remote sensing. Ten transects of 50 meters in length with sampling points every 5 meters from pipeline to undisturbed background area were selected in three different natural zones. The soil and vegetation cover was described, sampled, active layer of soil and the power of organic horizon were measured, the hydrothermal regime of soils in a layer of 0-10 cm was measured, the emission of greenhouse gas was studied. In the laboratory, the content of labile carbon, microbial biomass carbon, basal and substrate-induced respiration were measured. The main effect of the pipelines impact is the active degradation of permafrost and changes in hydrothermal settings. From background to broken areas the following settings changing: the depth of thawing increase in 10 times; the soil temperature changes from 4 to 10.5 °C in taiga, from 4.5 to 13.5 °C in tundra, from 5.5 to 12 C in forest-tundra; the soil moisture reduces from 20% to 10% in the tundra and forest tundra and from 45.5% to 7.7% in taiga. As a result, we established a significant transformation of ecosystems along pipelines, primarily due to a change in the hydrothermal regime of soils due to permafrost degradation. There is not only a change in the functioning and properties of soil, but also in the species composition of vegetation. There are the increasing of its biomass, expansion of woody vegetation along pipelines in the north. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1560.pdf

2018012881 Scherler, Dirk (German Research Centre for Geosciences, Potsdam, Germany). Geomorphic feedbacks between hillslopes and valley glaciers; implications for climate reconstructions and landscape evolution [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-2286, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Glacial landscapes respond rapidly to global warming: glaciers retreat, permafrost degrades, and snow cover diminishes. These changes affect the stability of glacial landscapes, manifested by enhanced rockfall activity and more frequent catastrophic slope failures. Similar changes have accompanied deglaciation after the last glacial maximum, albeit of much greater magnitude, and with potentially important feedbacks between the dynamics of mountain glaciers and the landscapes they reside in. Here, I summarize recent observations from debris-covered valley glaciers and put them into context with a more general conceptual model of how glacial landscapes respond to warming periods. I will identify key research problems and provide preliminary results from ongoing studies. Ice-free areas that are located above glaciers generally consist of steep bedrock hillslopes (headwalls), where ambient temperatures are low enough to form bedrock permafrost, but the topography is too steep to accumulate significant amounts of ice on the surface. Because headwalls erode by rockfalls and rock avalanches that mobilize fractured bedrock, the rate-limiting factor is the growth of bedrock fractures. Current theory posits that bedrock fractures in cold regions primarily expand by segregation ice growth at subfreezing temperatures, which is known as frost cracking. Because frost cracking is temperature sensitive, there exists a temperature window of high frost-cracking intensity, which is thought to correspond to an elevation zone of enhanced sediment production. During warming periods, changes in the frost-cracking intensity combine with permafrost degradation and changing stresses due to ice thinning to destabilize steep headwalls and likely increase the flux of rocks that is shed to valley glaciers below. Even if temporarily buried in the ice, most rocks eventually melt out at the ice surface and form a supraglacial debris cover. Because debris cover thicker than 2 cm reduces conductive heat transport and thus ice melt rates, heavily debris-covered glaciers are longer and extent to lower and warmer elevations compared to debris-free glaciers, all other things being equal. Therefore, if warming induces an increase in headwall erosion rates, the increased supply of rocks should lead to an increase in supraglacial debris cover, which would reduce ice melting and slow down glacier retreat. Theoretically this effect could offset part of the warming-induced glacier shrinking. Large slope failures that result in a sudden increase in debris cover may even trigger glacier advances, as has been proposed for a few glaciers already. Such geomorphic feedbacks between headwalls and valley glaciers ought to be most pronounced in steep landscapes like the Himalaya, where existing glacial chronologies often lack spatial coherence. Some heavily debris-covered valley glaciers can be found to lie entirely below the regional climatic snowline where they are sustained by snow avalanches. Such glaciers typically flow at low velocities and their key role in glacial landscape evolution may lie in keeping the base of headwalls free from talus deposits and thereby sustain a steep and retreating headwall. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-2286.pdf

2018012745 Siewert, Matthias (Stockholm University, Department of Physical Geography, Stockholm, Sweden) and Hugelius, Gustaf. High-resolution mapping and spatial variability of soil organic carbon storage of permafrost-affected soils [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1332, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Permafrost-affected soils store large amounts of soil organic carbon (SOC). Mapping of this SOC provides a first order spatial input variable for research that relates carbon stored in permafrost regions to carbon cycle dynamics. High-resolution satellite imagery is becoming increasingly available even in circum-polar regions. The presented research highlights findings of high-resolution mapping efforts of SOC from five study areas in the northern circum-polar permafrost region. These study areas are located in Siberia (Kytalyk, Spasskaya Pad /Neleger, Lena delta), Northern Sweden (Abisko) and Northwestern Canada (Herschel Island). Our high spatial resolution analyses show how geomorphology has a strong influence on the distribution of SOC. This is organized at different spatial scales. Periglacial landforms and processes dictate local scale SOC distribution due to patterned ground. Such landforms are non-sorted circles and ice-wedge polygons of different age and scale. Palsas and peat plateaus are formed and can cover larger areas in Sub-Arctic environments. Study areas that have not been affected by Pleistocene glaciation feature ice-rich Yedoma sediments that dominate the local relief through thermokarst formation and create landscape scale macro environments that dictate the distribution of SOC. A general trend indicates higher SOC storage in Arctic tundra soils compared to forested Boreal or Sub-Arctic taiga soils. Yet, due to the shallower active layer depth in the Arctic, much of the SOC may be permanently frozen and thus not be available to ecosystem processes. Significantly more SOC is stored in soils compared to vegetation, indicating that vegetation growth and incorporation of the carbon into the plant phytomass alone will not be able to offset SOC released from permafrost. This contribution also addresses advances in thematic mapping methods and digital soil mapping of SOC in permafrost terrain. In particular machine-learning methods, such as support vector machines, artificial neural networks and random forests show promising results as a toolbox for mapping permafrost-affected soils. Yet, these new methods do not decrease our dependency from soil pedon data from the field. In contrary, soil pedon data represents an urgent research priority. Statistical analyses are provided as an indication for best practice of soil pedon sampling for the quantification and the model representation of SOC stored in permafrost-affected soils. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1332.pdf

2018016135 Sperlich, Peter (University of Copenhagen, Centre for Ice and Climate, Copenhagen, Denmark); Schaefer, Hinrich; Fletcher, Sara Mikaloff; Guillevic, Myriam; Lassey, Keith; Sapart, Célia; Röckmann, Thomas and Blunier, Thomas. Carbon isotope ratios suggest no additional methane from boreal wetlands during the rapid Greenland Interstadial 21.2 [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1122, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Samples from two Greenland ice cores (NEEM and NGRIP) have been measured for methane carbon isotope ratios (d13C-CH4) to investigate the CH4 mixing ratio anomaly during Greenland Interstadial (GI) 21.2 (85,000 years before present). This extraordinarily rapid event occurred within 150 years, comprising a CH4 mixing ratio pulse of 150 ppb (~25%). Our new measurements disclose a concomitant shift in d13C-CH4 of 1 ppm. Keeling plot analyses reveal the d13C of the additional CH4 source constituting the CH4 anomaly as -56.8±2.8 ppm, which we confirm by means of a previously published box model. We propose tropical wetlands as the most probable additional CH4 source during GI-21.2 and present independent evidence that suggests that tropical wetlands in South America and Asia have played a key role. We find no evidence that boreal CH4 sources, such as permafrost degradation, contributed significantly to the atmospheric CH4 increase, despite the pronounced warming in the Northern Hemisphere during GI-21.2. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1122.pdf

2018016326 Uxa, Tomas (Charles University, Department of Physical Geography and Geoecology, Prague, Czech Republic) and Mida, Peter. Ground surface thermal regime of rock glaciers in the High Tatra Mts., Slovakia [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-1740, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Numerous lobate- or tongue-shaped debris accumulations, mostly interpreted as rock glaciers, have recently been recognized in the High Tatra Mts., Slovakia (49°10' N, 20°08' E). These prominent landforms arise due to creep of voluminous debris-ice mixtures, and as such they are excellent indicators of present or past permafrost existence. Hence rock glaciers are extensively utilized to model the distribution of permafrost in mountain areas. However, commonly applied rules of thumb may not be entirely indicative to discriminate particularly between the inactive (permafrost in disequilibrium with present climate) and relict (without permafrost) rock glaciers, which may substantially complicate permafrost modelling. Accordingly, the information about their thermal state is essential to calibrate and validate regional permafrost models. Limited ground temperature data have been, however, available from the High Tatra Mts. to date and therefore, we bring the updated and enhanced results from the thermal investigations of eleven rock glaciers located in the Slavkovska dolina and Vel'ka Studena dolina valleys at elevations between 1832 and 2090 m asl. Ground surface temperature (GST) has been continuously monitored at seven rock glaciers between October 2014 and September 2016 using nine Minikin Tie (EMS Brno Inc.) and iButton DS1922L (Maxim Integrated Inc.) loggers with an accuracy of 0.2 and 0.5 °C, respectively. In addition, the bottom temperature of snow (BTS) was measured at 306 locations during spring of 2015 and 2016 to map potential permafrost occurrence within all the surveyed rock glaciers and in their immediate surroundings. Mean annual ground surface temperature (MAGST) of the rock glaciers ranged between -1.3 °C and +2.6 °C and averaged +1.0 °C and +0.8 °C in 2014-2015 and 2015-2016, respectively. Two sites continually showed negative MAGST and two other sites were below +0.5 °C and +1.0 °C, respectively. This strongly contrasts with mean annual air temperature (MAAT), which averaged +2.3 °C in both years (estimated from nearby Lomnicky stit station using a lapse rate of 6.5 °C/km). Accordingly, GSTs showed negative surface offset (MAGST-MAAT) of -1.3 °C and -1.5 °C in 2014-2015 and 2015-2016, respectively. At the coldest sites, the surface offset regularly reached values well below -2 °C and dropped up to -3.3 °C. GSTs recorded prior to the onset of snow melting (i.e. BTS) averaged -3.8 °C and -3.2 °C in spring of 2015 and 2016, respectively, and varied between -5.8 °C and -1.6 °C. One-time BTS values showed the average of -2.8 °C, but relatively high short-distance heterogeneity of BTS values, ranging between -8.3 °C and 0.0 °C, was encountered across the rock-glacier surfaces. The results suggest that permafrost occurrence is probable or possible in a total of ten rock glaciers, while its absence is probable only in one of the investigated landforms. We classify the latter form as relict and other two rock glaciers are suggested to be in inactive/relict state. Six rock glaciers are believed to be inactive and two even active/inactive. In most cases, however, permafrost likely occurs in a form of isolated patches or discontinuously and presumably degrades under present climate conditions. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-1740.pdf

2018014118 Voigt, Carolina (University of Eastern Finland, Department of Environmental and Biological Sciences, Kuopio, Finland); Lamprecht, Richard E.; Marushchak, Maija E.; Lind, Saara E.; Novakovskiy, Alexander; Aurela, Mika; Martikainen, Pertti J. and Biasi, Christina. Enhanced greenhouse gas emissions from the Arctic with experimental warming [abstr.]: in European Geosciences Union general assembly 2017, Geophysical Research Abstracts, 19, Abstract EGU2017-495, 2017. Meeting: European Geosciences Union general assembly 2017, April 23-28, 2017, Vienna, Austria.

Temperatures in the Arctic are projected to increase more rapidly than in lower latitudes. With temperature being a key factor for regulating biogeochemical processes in ecosystems, even a subtle temperature increase might promote the release of greenhouse gases (GHGs) to the atmosphere. Usually, carbon dioxide (CO₂) and methane (CH₄) are the GHGs dominating the climatic impact of tundra. However, bare, patterned ground features in the Arctic have recently been identified as hot spots for nitrous oxide (N₂O). N₂O is a potent greenhouse gas, which is almost 300 times more effective in its global warming potential than CO₂; but studies on arctic N₂O fluxes are rare. In this study we examined the impact of temperature increase on the seasonal GHG balance of all three important GHGs (CO₂, CH₄ and N₂O) from three tundra surface types (vegetated peat soils, unvegetated peat soils, upland mineral soils) in the Russian Arctic (67°03'N 62°55'E), during the course of two growing seasons. We deployed open-top chambers (OTCs), inducing air and soil surface warming, thus mimicking predicted warming scenarios. We combined detailed CO₂, CH₄ and N₂O flux studies with concentration measurements of these gases within the soil profile down to the active layer-permafrost interface, and complemented these GHG measurements with detailed soil nutrient (nitrate and ammonium) and dissolved organic carbon (DOC) measurements in the soil pore water profile. In our study, gentle air warming (~1.0°C) increased the seasonal GHG release of all dominant surface types: the GHG budget of vegetated peat and mineral soils, which together cover more than 80% of the land area in our study region, shifted from a sink to a source of -300 to 144 g CO₂-eq m^-2 and from -198 to 105 g CO₂-eq m^-2, respectively. While the positive warming response was governed by CO₂, we provide here the first in situ evidence that warming increases arctic N₂O emissions: Warming did not only enhance N₂O emissions from the known arctic N₂O hot spots (bare peat soils; maximum seasonal release with warming: 87 mg N₂O m^-2), but also from the vegetated peat surfaces, not emitting N₂O under present climate. These surfaces showed signs of a hampered plant growth, leading to reduced soil N uptake with warming, indicating that plants are regulating arctic N₂O emissions. The warming treatment was limited to temperature of air and upper soil surface, and did not alter thaw depth. Nonetheless, we observed a clear increase of all three GHGs deep in the soil profile, and attribute this to downward leaching of labile organic substances from the surface soil and/or plants, fueling microbial activity at depth. Our study thus highlights the tight interlinkage between the surface soil, vegetation, and deeper soil layers, which could lead to losses of all three GHGs, including N₂O, with subtle temperature increase. We therefore emphasize that indirect effects caused by warming, such as leaching processes, as well as arctic N₂O emissions, need to be taken into account when attempting to project feedbacks between the arctic and the global climate system. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]

URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-495.pdf

2018015279 Dadfar, B. (Western University, Department of Civil and Environmental Engineering, London, ON, Canada); El Naggar, M. H. and Nastev, M. Seismic behavior of buried energy pipelines in northern permafrost regions: in 6ICEGE; 6th international conference on Earthquake geotechnical engineering; proceedings (Cubrinovski, Misko, chairperson; et al.), New Zealand Geotechnical Society, New Zealand, 8 p., illus. incl. 1 table, 7 ref., 2015. Meeting: 6th international conference on Earthquake geotechnical engineering, Nov. 1-4, 2015, Christchurch, New Zealand. Paper no. 598.

URL: https://secure.tcc.co.nz/ei/images/ICEGE15%20Papers/Dadfar_598.00.pdf

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