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2022019581 Park, Sang Eun (Sejong University, Department of Energy Resources and Geosystems Engineering, Seoul, South Korea); Jung, Yoon Taek and Kim, Hyun Cheol. Monitoring permafrost changes in central Yakutia using optical and polarimetric SAR data: Remote Sensing of Environment, 274, Article 112989, illus. incl. 5 tables, sketch maps, June 1, 2022.
The changes in the permafrost environment have been of interest as a sensitive indicator of changes in global climate conditions. Since changes in the soil and ecosystem of the permafrost active layer are spatially and temporally complex depending on many environmental factors, it is not easy to grasp climate-induced changes occurring in coupled atmospheric-ecological-geocryological systems. To understand the changes in the permafrost active layer, spatially detailed monitoring methods such as multi-spectral optical and Synthetic Aperture Radar (SAR) remote sensing technologies have been extensively applied to the permafrost observation. Optical and SAR systems observe different permafrost features due to significant differences in electromagnetic wave frequencies and imaging mechanisms. Therefore, most studies used optical and SAR data separately according to the purpose and characteristics of each study. The objective of this study is to explore the possibility of combined interpretation of optical and SAR data for identifying and understanding spatiotemporal details of the short- and long-term changes occurring in the permafrost active layer. Multi-spectral optical images acquired during the thawing period and L-band polarimetric SAR images acquired during the freezing period are used in this study in order to examine ecological characteristics and cryogenic processes, respectively. The result of analyzing the relationship between information obtained from optical and SAR sensors revealed that there was a significant correlation between winter changes in scattering properties observed in SAR data and summer land cover changes observed in optical data. The scattering characteristics of winter soil were found to be particularly related to the ecosystem changes in areas that can be explained by the thermokarst development process. Additional data from independent sources, such as elevation data, meteorological data, and long-term optical data, consistently supported the relationship between the winter SAR observations and the thermokarst-related ecosystem changes. The experimental results also elucidated that polarimetric scattering mechanism indicators representing the signal depolarization and surface roughness properties played an important role in deriving information related to the permafrost process from the winter SAR data.
DOI: 10.1016/j.rse.2022.112989
2022019411 Wu Tonghua (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, State Key Laboratory of Cryospheric Science, Lanzhou, China); Ma Wensi; Wu Xiaodong; Li Ren; Qiao Yongping; Li Xiangfei; Yue Guangyang; Zhu Xiaofan and Ni Jie. Weakening of carbon sink on the Qinghai-Tibet Plateau: Geoderma, 412, Article 115707, illus. incl. 1 table, geol. sketch map, 80 ref., April 15, 2022.
Cold regions contain a large amount of soil organic carbon, and the warming-accelerated loss of this carbon pool could cause important feedback to climatic change. The changes of carbon budgets in cold regions are poorly quantified especially for the Qinghai-Tibet Plateau (QTP) due to limited field observation data. By considering the soil freeze-thaw process and establishing new plant functional types with localized parameters, we used the Integrated Biosphere Simulator (IBIS) model to simulate the changes of carbon budget on the QTP during 1980-2016. The model was calibrated and validated using carbon flux data from eddy covariance observations at 16 sites. The results showed that the QTP has assimilated 43.16 Tg C/yr during 1980-2016, with permafrost and non-permafrost regions accounting for approximately 15% and 85% of the carbon sink, respectively. During the past four decades, the gross primary production and ecosystem respiration have increased by 1.74 and 2.04 Tg C/yr2, resulting in that the carbon sink on the QTP has weakened during 1980-2016. Moreover, the weakening of carbon sink is more pronounced in the non-permafrost regions. We project that the ecosystems will release 12.30 and 24.40 Tg C by 2080-2100 under the moderate and high shared socio-economic pathways (SSP 370 and SSP 585), respectively. This could largely offset the carbon sink and even shift the carbon sink to carbon source on the QTP.
DOI: 10.1016/j.geoderma.2022.115707
2022019547 Abdelhamed, Mohamed S. (University of Saskatchewan, Global Institute for Water Security, Saskatoon, SK, Canada); Elshamy, Mohamed E.; Wheater, Howard S. and Razavi, Saman. Hydrologic land surface modelling of the Canadian sporadic discontinuous permafrost; initialization and uncertainty propagation: Hydrological Processes, 36(3), Article e14509, illus. incl. sect., 2 tables, geol. sketch map, 105 ref., March 2022.
Permafrost thaw has been observed in recent decades in the Northern Hemisphere and is expected to accelerate with continued global warming. Predicting the future of permafrost requires proper representation of the interrelated surface/subsurface thermal and hydrologic regimes. Land surface models (LSMs) are well suited for such predictions, as they couple heat and water interactions across soil-vegetation-atmosphere interfaces and can be applied over large scales. LSMs, however, are challenged by the long-term thermal and hydraulic memories of permafrost and the paucity of historical records to represent permafrost dynamics under transient climate conditions. In this study, we aim to understand better how LSMs function under different spin-up states, which facilitates addressing the challenge of model initialization by characterizing the impact of initial climate conditions and initial soil frozen and liquid water contents on the simulation length required to reach equilibrium. Further, we quantify how the uncertainty in model initialization propagates to simulated permafrost dynamics. Modelling experiments are conducted with the Modélisation Environmentale Communautaire-Surface and Hydrology (MESH) framework and its embedded Canadian land surface scheme (CLASS). The study area is in the Liard River basin in the Northwest Territories of Canada with sporadic and discontinuous regions. Results show that uncertainty in model initialization controls various attributes of simulated permafrost, especially the active layer thickness, which could change by 0.5-1.5 m depending on the initial condition chosen. The least number of spin-up cycles is achieved with near field capacity condition, but the number of cycles varies depending on the spin-up year climate. We advise an extended spin-up of 200-1000 cycles to ensure proper model initialization under different climatic conditions and initial soil moisture contents. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/hyp.14509
2022019286 Lim, Artem G. (Tomsk State University, BIO-GEO-CLIM Laboratory, Tomsk, Russian Federation); Loiko, Sergey V. and Pokrovsky, Oleg S. Sizable pool of labile organic carbon in peat and mineral soils of permafrost peatlands, western Siberia: Geoderma, 409, Article 115601, illus. incl. 2 tables, sketch map, 90 ref., March 1, 2022.
In contrast to good knowledge of dissolved organic matter (DOM) adsorption on mineral soils in temperate climate, the behavior of DOM in frozen mineral horizons located under peat soils of permafrost-affected regions remains poorly characterized. Yet, these regions contain sizeable and potentially highly labile pools of organic (peat) carbon (C) that may migrate downwards across mineral layers in case of massive thaw in frozen peatlands induced by on-going climate warming. To quantify these pools and the ability of DOM in permafrost peat soils, we performed experiments focusing on dissolved organic carbon (DOC) desorption from, and adsorption onto, mineral horizons (iron-poor and iron-rich sands as well as silt loam) from the largest frozen peatland in the world, the Western Siberia Lowland (WSL). Desorbed DOC ranged between 0.1 and 0.6 mg C gsoil-1 depending on type of mineral substrate. The adsorption of peat leachate DOM ranged between 0.1 and 0.5 mg C gsoil-1 being highest in Al-Fe-rich mineral horizons. Field measurements of C pools in peat and underlying mineral horizons over 1 m depth in the discontinuous permafrost zone yielded 47 and 15 kg C m-2, respectively. The organic carbon (OC) adsorption capacity of the 1 m-thick mineral layers represented <2% of total amount of OC containing in the 1 m-thick peat layer. However, this adsorption capacity is comparable to the amount of DOC that can be leached from overlaying peat horizons (18%). On average, out of 1.38 ± 0.13 kg C m-2 capable of being initially released from the upper 0-100 cm of peat, 0.25 ± 0.19 kg C m-2 can be adsorbed by the underlying 100-200 cm of Fe- and Al-rich sands and clays. The remaining 1.13 kg C m-2 can be exported to lakes and rivers. Therefore, DOC released during peat thaw in upper soil horizons in permafrost regions can be sizably attenuated via adsorption on mineral layers. This should be taken into account when modeling the feedback of permafrost thaw on C export and CO2 emissions.
DOI: 10.1016/j.geoderma.2021.115601
2022019304 Ming Jiao (Chinese Academy of Sciences, Institute of Soil and Water Conservation, State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Yangling, China); Zhao Yunge; Wu Qingbai; He Hailong and Gao Liqian. Soil temperature dynamics and freezing processes for biocrustal soils in frozen soil regions on the Qinghai-Tibet Plateau: Geoderma, 409, Article 115655, illus. incl. 2 tables, sketch map, 69 ref., March 1, 2022.
The relationship between soil temperature and its variations with different types of land cover are critical to understanding the effects of climate warming on ecohydrological processes in frozen soil regions such as the Qinghai-Tibet Plateau (QTP) of China. Biological soil crusts (biocrusts), which cover approximately 40% of the open soil surface in frozen soil regions, exert great impacts on soil temperatures. However, little attention has been given to the potential effects of biocrusts on the temperature characteristics, dynamics and freezing duration of soil in frozen soil regions. To provide more insight into this issue, an automatic system was used to monitor soil temperatures and dynamics at depths of 5, 30, 50 and 100 cm beneath bare soil and two types of biocrustal soils (soils covered with two types of biocrusts) on the QTP of China. The results showed that biocrusts play an important role in controlling the dynamics of soil temperatures. Biocrusts cause a 0.6-1°C decrease in the mean annual temperature of soils down to a depth of 100 cm. The extent of the decrease in soil temperature was dependent on biocrust type, and dark biocrust showed a greater reduction in soil temperature than light biocrust. In addition, reductions in soil temperatures of biocrusts mainly occurred in daytimes of the thawing period, and this prolonged the freezing duration in the top 100 cm by approximately 10-20 days. The results of this study indicate that biocrusts maintain lower temperatures in the thawing period and slow the thawing of frozen soil in the spring, which helps to maintain the stability of the frozen soil. This information may aid understanding of the function of biocrusts in the frozen soil regions under global warming conditions.
DOI: 10.1016/j.geoderma.2021.115655
2022016836 Glover, P. W. J. (University of Leeds, School of Earth and Environment, Leeds, United Kingdom) and Blouin, M. Increased radon exposure from thawing of permafrost due to climate change: Earth's Future, 10(2), Article e2021EF002598, illus. incl. 1 table, 51 ref., February 2022.
Radon is a natural radioactive gas accounting for approximately one in 10 lung cancer deaths, with substantially higher death rates in sub-Arctic communities. Radon transport is significantly reduced in permafrost, but permafrost is now thawing due to climate change. The effect of permafrost thawing on domestic radon exposure is unknown. Here we present results from radon transport modeling through soil, permafrost, and model buildings either with basements or built on piles. We find that permafrost acts as an effective radon barrier, reducing radiation exposure to a tenth of the background level while producing a ten-fold increase in the radon activity behind the barrier. When we model thawing of the permafrost barrier, we find no increase in radon to the background level for buildings on piles. However, for buildings with basements, the radon increases to over one hundred times its initial value and can remain above the 200 Bq/m3 threshold for up to 7 years depending on the depth of the permafrost and the speed of thawing. When thawing speed is taken into account, radiations remain higher than the threshold for all scenarios where 40% thawing occurs within 15 years. This new information suggests that a significant sub-Arctic population could be exposed to radon levels dangerous to health as a result of climate change thawing of permafrost, with implications for health provision, building codes, and ventilation advice. Abstract Copyright (2022), The Authors. Earth's Future published by Wiley Periodicals LLC on behalf of American Geophysical Union.
DOI: 10.1029/2021EF002598
2022016407 Mason, Daniel P. (University of Oklahoma, School of Geosciences, Norman, OK) and Elwood Madden, Megan E. Raman spectroscopy of high salinity brines and ices: Icarus, 372, Article 114759, illus. incl. 3 tables, 67 ref., January 15, 2022. Includes appendix.
Raman spectroscopy is an ideal tool to analyze the geochemistry and mineralogy of heterogenous mixtures of solids, liquid, and gases in situ, while maintaining planetary protection protocols. Here we characterize saturated CaCl2, MgCl2, MgSO4, Na2SO4, NaCl, and NaClO4 brines, as well as ultrapure water, and mixed MgSO4-NaCl, MgSO4-NaClO4, Na2SO4-NaCl, Na2SO4-NaClO4, and NaCl-NaClO4 brines from 200 K to 295 K to determine how changes in temperature affect spectral signatures of planetary analog brines. The resulting reference dataset can be used to interpret spectra from future samples analyzed in situ on planetary bodies. Sulfate and perchlorate brines produced clear, distinct peaks associated with each polyatomic anion. While chloride brines did not produce anion peaks, subtle changes were observed in the OH-stretching region, suggesting changes to the molecular water vibration states due to complexation. Solid-liquid phase transitions were clearly observed in each of the solutions using both 785 nm (red) and 532 nm (green) excitation lasers, particularly in the OH-stretching region between 3000 and 4000 cm-1 with the 532 nm laser. Differences observed in the spectra of frozen sulfate brines suggest that cooling rates may influence the hydration state and/or crystallinity of the solid magnesium and sodium-sulfate salts. These experiments and the resulting spectral library will allow future researchers to use Raman spectroscopy to look for in situ melting, freezing, evaporation, and deliquescence as well as identify the composition of high salinity brines and their frozen products in a range of planetary environments, including permafrost and recurring slope lineae on Mars, potential ice and salt-rich regolith on asteroids such as Ceres, and ice shells and possible seeps or geysers on icy moons and other bodies.
DOI: 10.1016/j.icarus.2021.114759
2022018323 Murton, Julian B. (University of Sussex, Department of Geography, Permafrost Laboratory, Brighton, United Kingdom); Opel, Thomas; Toms, Phillip; Blinov, Alexander; Fuchs, Margret; Wood, Jamie; Gärtner, Andreas; Merchel, Silke; Rugel, Georg; Savvinov, Grigoriy and Wetterich, Sebastian. A multimethod dating study of ancient permafrost, Batagay megaslump, east Siberia: Quaternary Research, 105, p. 1-22, illus. incl. strat. cols., 6 tables, sketch map, 107 ref., 2022.
Dating of ancient permafrost is essential for understanding long-term permafrost stability and interpreting palaeoenvironmental conditions but presents substantial challenges to geochronology. Here, we apply four methods to permafrost from the megaslump at Batagay, east Siberia: (1) optically stimulated luminescence (OSL) dating of quartz, (2) post-infrared infrared-stimulated luminescence (pIRIR) dating of K-feldspar, (3) radiocarbon dating of organic material, and (4) 36Cl/Cl dating of ice wedges. All four chronometers produce stratigraphically consistent and comparable ages. However, OSL appears to date Marine Isotope Stage (MIS) 3 to MIS 2 deposits more reliably than pIRIR, whereas the latter is more consistent with 36Cl/Cl ages for older deposits. The lower ice complex developed at least 650 ka, potentially during MIS 16, and represents the oldest dated permafrost in western Beringia and the second-oldest known ice in the Northern Hemisphere. It has survived multiple interglaciations, including the super-interglaciation MIS 11c, though a thaw unconformity and erosional surface indicate at least one episode of permafrost thaw and erosion occurred sometime between MIS 16 and 6. The upper ice complex formed from at least 60 to 30 ka during late MIS 4 to 3. The sand unit above the upper ice complex is dated to MIS 3-2, whereas the sand unit below formed at some time between MIS 4 and 16.
DOI: 10.1017/qua.2021.27
2022019493 Wang, Yucheng (University of Cambridge, Department of Zoology, Cambridge, United Kingdom); Pedersen, Mikkel Winther; Alsos, Inger Greve; De Sanctis, Bianca; Racimo, Fernando; Prohaska, Ana; Coissac, Eric; Owens, Hannah Lois; Merkel, Marie Kristine Foreid; Fernandez-Guerra, Antonio; Rouillard, Alexandra; Lammers, Youri; Alberti, Adriana; Denoeud, France; Money, Daniel; Ruter, Anthony H.; McColl, Hugh; Larsen, Nicolaj Krog; Cherezova, Anna A.; Edwards, Mary E.; Fedorov, Grigory B.; Haile, James; Orlando, Ludovic; Vinner, Lasse; Korneliussen, Thorfinn Sand; Beilman, David W.; Bjork, Anders A.; Cao, Jialu; Dockter, Christoph; Esdale, Julie; Gusarova, Galina; Kjeldsen, Kristian Kjellerup; Mangerud, Jan; Rasic, Jeffrey T.; Skadhauge, Birgitte; Svendsen, John Inge; Tikhonov, Alexei; Wincker, Patrick; Xing Yingchun; Zhang Yubin; Froese, Duane G.; Rahbek, Carsten; Nogues, David Bravo; Holden, Philip B.; Edwards, Neil R.; Durbin, Richard; Meltzer, David J.; Kjaer, Kurt H.; Moller, Per and Willerslev, Eske. Late Quaternary dynamics of Arctic biota from ancient environmental genomics: Nature (London), 600(7887), p. 86-92, illus. incl. sketch map, 62 ref., December 2, 2021.
DOI: 10.1038/s41586-021-04016-x
2022019278 Park, Jamin (University of Toronto, Department of Civil and Mineral Engineering, Toronto, ON, Canada); Kwon Oh-Sung and Di Sarno, Luigi. Influence of seasonal soil temperature variation and global warming on the seismic response of frozen soils in permafrost regions: Earthquake Engineering & Structural Dynamics, 50(14), p. 3855-3871, illus. incl. 2 tables, 26 ref., November 2021.
There has been growing interest in seismic hazards in permafrost regions as development in those regions has increased. Because major infrastructure, such as natural gas pipelines, has been constructed in permafrost regions, it is necessary to evaluate the seismic safety of such a network system. As frozen soil's dynamic properties differ from those of its unfrozen state, the characteristics of seismic waves propagated through frozen soil layers in permafrost differ from those propagated through unfrozen soil. Thus, the dynamic properties and composition of frozen soil layers located between bedrock and the ground surface need to be realistically considered in evaluating the seismic hazards of permafrost regions. The frozen soil layer's composition greatly depends on soil temperatures which vary seasonally and are gradually increasing due to global warming, therefore it is necessary to consider soil temperature variation. In this study, comprehensive parametric site response analysis was carried out based on measured data regarding seasonal and annual temperature variation to investigate seismic hazards. The soil temperature variation between summer and winter and temperature increases due to global warming were the main considerations. The analysis results clearly show that the soil temperature variation significantly impacts seismic hazards in the permafrost region, leading to different site response characteristics than those in the non-permafrost region. Abstract Copyright (2021), John Wiley & Sons, Ltd.
DOI: 10.1002/eqe.3536
2022019255 Zhang Zhenyu (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Lanzhou, China); Yu Qihao; Wang Junfeng; Wang Xinbing and Luo Xiaoxiao. Bidirectional convection mechanism and cooling performance of road embankment with a new duct-ventilated slope in permafrost regions: Cold Regions Science and Technology, 191, Paper no. 103360, illus., November 2021. Based on Publisher-supplied data.
Embankment with duct-ventilated slope (EDVS) is a new kind of proactive roadbed cooling measure in permafrost regions, which is composed of multiple hollow cement ventilation ducts assembled side by side, and the ducts are laid down on embankment slope. To investigate its cooling mechanism and performance, a prototype field test was carried out on the Qinghai-Tibet Plateau. The in-situ flow visualization test revealed that EDVS can conduct the convection process of airflow upward parallel to the embankment slope at the windward slope and downward parallel to the slope at the leeward slope. Thus, the bidirectional airflow in the ducts is available, which is termed as "bidirectional convection mechanism" and first discovered in embankment slope cooling measures. The numerical simulation results indicated that the wind pressure gradient is the primary reason for the bidirectional convection mechanism. The bidirectional convection mechanism can effectively utilize the low-temperature air to reduce the subgrade temperature in cold seasons. The monitored data showed that EDVS reduced the annual average slope temperature by 3.8°C compared to the traditional no-covered embankment. EDVS provides new research for roadbed cooling measures in permafrost regions.
DOI: 10.1016/j.coldregions.2021.103360
2022017884 Heinze, T. (Ruhr-University Bochum, Institute of Geology, Mineralogy and Geophysics, Hydrogeochemistry and Hydrogeology, Bochum, Germany). A multi-phase heat transfer model for water infiltration into frozen soil: Water Resources Research, 57(10), Article e2021WR030067, illus. incl. 2 tables, 66 ref., October 2021.
In many regions, water infiltration into frozen soil is a critical process. Frozen soil is known to have a substantially reduced infiltration capacity, resulting in surface water runoff. This surface runoff is often associated with erosive behavior posing a potential natural hazard as it facilitates snow avalanches and debris flow, especially in springtime when rainfall and snowmelt coincide. As infiltration capacity depends on the ice content within the porous soil, thermal and hydraulic processes are strongly coupled. The involved phases during water infiltration into frozen soil are initially not in a local thermal equilibrium as the infiltrated water is warmer than the frozen soil. The duration of the temperature differences is yet to be determined. To adequately describe this thermal state, a local thermal non-equilibrium (LTNE) model needs to be applied, which accounts for separate phase temperatures and describes the heat transfer between the phases explicitly. While LTNE models are common in more simple setups of saturated porous media flow, in this work, a multi-phase LTNE model for water infiltration into a partly saturated, frozen soil is presented. All required parameters, such as heat transfer area and heat transfer coefficient are discussed and derived based on a capillary tube model. The theoretical model is implemented into a numerical model and compared to experimental data available from literature. Substantial differences of up to 0.5°C between phase temperatures during freezing and melting are observed after hours of infiltration and are especially pronounced around the freezing front. Abstract Copyright (2021), . The Authors.
DOI: 10.1029/2021WR030067
2022017887 Zhang, Ting (National University of Singapore, Department of Geography, Singapore, Singapore); Li, Dongfeng; Kettner, Albert J.; Zhou Yinjun and Lu, Xixi. Constraining dynamic sediment-discharge relationships in cold environments; the sediment-availability-transport (SAT) model: Water Resources Research, 57(10), Article e2021WR030690, illus. incl. 5 tables, sketch maps, 69 ref., October 2021.
Accelerated glacier-snow-permafrost erosion due to global warming amplifies the sediment availability in cold environments and affects the time-varying suspended sediment concentration (SSC) and discharge (Q) relationship. Here, the sediment-availability-transport (SAT) model is proposed to simulate dynamic SSC-Q relationships by integrating the sediment availability coupled by thermal processes, fluvial processes and long-term storage exhaustion into a sediment rating curve (SSC = a ´ Qb with a and b as fitting parameters). In the SAT-model, increased sediment sources from glacier-snow-permafrost erosion are captured by changes in basin temperature, showing an exponential amplification of SSC when basin temperature increases. Enhanced fluvial erosion by the elevated water supply from rainfall and meltwater is captured by the factor of runoff surge, which results in a linear amplification of SSC. The SAT-model is validated for the permafrost-dominated Tuotuohe basin on Tibetan Plateau utilizing multi-decadal daily SSC/Q in-situ observations (1985-2017). Results show that sediment rating curves for Tuotuohe display significant inter-annual variations. The higher parameter-b in a warmer and wetter climate confirms the increased sediment availability due to the expanded erodible landscapes and gullying-enhanced connectivity between channels and slopes. Through capturing such time-varying sediment availability, the SAT-model can robustly reproduce the long-term evolution, seasonality, and various event-scale hysteresis of SSC, including clockwise, counter-clockwise, figure-eight, counter-figure-eight, and more complex hysteresis loops. Overall, the SAT-model can explain over 75% of long-term SSC variance with stable performance under hydroclimate abrupt changes, outperforming the conventional and static sediment rating curve approach by 20%. The SAT-model not only advances understanding of sediment transport mechanisms by integrating thermal- and fluvial-erosion processes, but also provides a model framework to simulate and project future sediment loads in other cold basins. Abstract Copyright (2021), . American Geophysical Union. All Rights Reserved.
DOI: 10.1029/2021WR030690
2022016150 Matyshak, G. V. (Lomonosov Moscow State University, Moscow, Russian Federation); Tarkhov, M. O.; Ryzhova, I. M.; Goncharova, O. Yu.; Sefiliyan, A. R.; Chuvanov, S. V. and Petrov, D. G. Temperature sensitivity of SO2 efflux from the surface of palsa peatlands in northwestern Siberia as assessed by transplantation method: Eurasian Soil Science, 54(7), p. 1028-1037, illus. incl. 2 tables, 45 ref., July 2021.
Peatland soils in permafrost area are among the major components of global carbon cycle. In the case of predicted climate change, they may act as a significant source of greenhouse gases efflux. A four-year transplantation experiment (transplantation of soil cores of 20 cm in height and 10 cm in diameter to other natural positions) with the peat horizon was arranged to assess the temperature sensitivity of CO2 efflux from palsa peatlands in the north of Western Siberia. The rise in temperature by 7°S caused a positive feedback (30-70%) of CO2 efflux (measured by the closed chamber method) from transplanted soils as compared with the control. Temperature dependence of CO2 efflux from transplanted soils had the highest value (R2=0.8) in the first two years as a result of maximum contrast of temperature conditions between sites and decreased in the next two years. On the contrary, the temperature sensitivity of CO2 efflux from transplanted soils showed a high value during most of observations (Q10=3-6) thus indicating the increased rate of organic matter mineralization in peat soils of permafrost area for a long (four years) period. Our results might be useful for calibration of regional carbon cycle data sets that consider the contribution of organic permafrost-affected soils.
DOI: 10.1134/S1064229321070103
2022016149 Vasil'chuk, Yu. K. (Lomonosov Moscow State University, Moscow, Russian Federation); Belik, A. D.; Budantseva, N. A.; Gennadiev, A. N.; Vasil'chuk, A. C.; Vasil'chuk, J. Yu.; Zavgorodnyaya, Yu. A.; Ginzburg, A. P. and Bludushkina, L. B. Polycyclic aromatic hydrocarbons and carbon isotopes in a palsa peat (Bol'shezemel'skaya Tundra): Eurasian Soil Science, 54(7), p. 999-1006, illus. incl. 1 table, 36 ref., July 2021.
The content of polycyclic aromatic hydrocarbons (PAHs) and carbon isotope composition in the peat of a palsa near Eletsky settlement, Vorkuta urban district, Komi Republic are analyzed. The carbon isotope composition of peat varies from -28.05 to -30.05 ppm (average -29.15 ppm). The total PAH content varies from 11 to 360 ppb, with an average of 63 ppb and a median value of 34 ppb. Heavy compounds, such as benzo(a)anthracene and benzofluoranthenes, are prevalent among PAHs. The presence of PAHs in the peat is determined by three main factors: technogenic impact, wildfires, and biogeochemical soil processes. The prevalence of benzo(a)anthracene in the upper part of the palsa down to the bottom of the active layer suggests an anthropogenic impact (the influence of transport and domestic fuel combustion). The share of benzo(a)anthracene decreases with depth, while the share of benzofluoranthenes increases. Two sharp peaks of PAH content (260 and 360 ppb) are observed; they coincide with a local increase of carbon isotope values, most likely resulting from wildfires. The minimums in PAH content are presumably determined by the biogeochemical factor and the input of polyarenes generated by decomposition of plant residues. Carbon isotope composition of peat mainly reflects the isotope composition of vegetation, the degree of peat moistening, and the influence of pyrogenic factor.
DOI: 10.1134/S1064229321070139
2022017777 Maslakov, Alexey (Lomonosov Moscow State University, Faculty of Geography, Moscow, Russian Federation); Zotova, Larisa; Komova, Nina; Grishchenko, Mikhail; Zamolodchikov, Dmitry and Zelensky, Gennady. Vulnerability of the permafrost landscapes in the eastern Chukotka coastal plains to human impact and climate change: Land (Basel), 10(5), Article 445, May 2021. Part of a special issue entitled Feature papers for land-climate interactions section, edited by Balzter, H.
Permafrost landscapes are particularly susceptible to the observed climate change due to the presence of ice in the ground. This paper presents the results of the mapping and assessment of landscapes and their vulnerability to potential human impact and further climate change in the remote region of Eastern Chukotka. The combination of field studies and remote sensing data analysis allowed us to identify the distribution of landscapes within the study polygon, reveal the factors determining their stability, and classify them by vulnerability to the external impacts using a hazard index, H. In total, 33 landscapes characterized by unique combinations of vegetation cover, soil type, relief, and ground composition were detected within the 172 km2 study polygon. The most stable landscapes of the study polygon occupy 31.7% of the polygon area; they are the slopes and tops of mountains covered with stony-lichen tundra, alpine meadows, and the leveled summit areas of the fourth glacial-marine terrace. The most unstable areas cover 19.2% of the study area and are represented by depressions, drainage hollows, waterlogged areas, and places of caterpillar vehicle passage within the terraces and water-glacial plain. The methods of assessment and mapping of the landscape vulnerability presented in this study are quite flexible and can be adapted to other permafrost regions.
DOI: 10.3390/land10050445
2022019211 Okoneshnikova, M. V. (Russian Academy of Sciences, Siberian Branch, Institute for Biological Problems of Cryolithozone, Yakutsk, Russian Federation); Ivanova, A. Z.; Desyatkin, R. V. and Nikolin, E. G. Soils of altitudinal zones of the Suntar-Khayata Ridge; morphology, properties, and classification: Eurasian Soil Science, 54(5), p. 680-688, illus. incl. 3 tables, sketch map, 32 ref., May 2021.
For the first time, a detailed diagnostics and classification of soils of the Suntar-Khayata Range have been performed. This study is a continuation of long-term soil research in the Verkhoyansk mountainous soil province. The morphogenetic properties of soils in different altitudinal zones of the Suntar-Khayata Range are described, and the position of these soils in the new Russian soil classification system is determined. The Suntar-Khayata Range (63°N; 139°E) is found near the Pole of Cold of the northern hemisphere and is characterized by the distinct altitudinal zonation. In the study area, parent materials are represented by sandstone and, less often, by siltstone. In the warm season, the upper boundary of permafrost can be clearly traced only in the profiles of low-stony soils on the floodplains. The vertical zonality in the studied area includes the following zones: the valley zone (<900 m a.s.l.) with alluvial soils (Skeletic Fluvisols), the mountainous taiga zone (900-1300 m a.s.l.) with a predominance of podburs (Skeletic Spodic Cryosols), and the subalpine shrub (1300-1500 m a.s.l.) and mountainous tundra (>1500 m a.s.l.) with a predominance of lithozems (Leptosols). All the soils are relatively shallow, stony, and coarse-textured; their organic horizons are thin, and raw-humus (AO) horizons tend to predominate. Gley features are absent in the soil profiles. The soils have an acid or a slightly acid reaction, low base saturation (except for alluvial soils), and signs of organic matter illuviation. The results of this study can be used to expand the database on soils of poorly studied cold continental mountain regions of Eurasia.
DOI: 10.1134/S1064229321050148
2022017776 Shestakova, Alyona A. (Russian Academy of Sciences, Siberian Branch, Melnikov Permafrost Institute, Yakutsk, Russian Federation); Fedorov, Alexander N.; Torgovkin, Yaroslav I.; Konstantinov, Pavel Y.; Vasyliev, Nikolay F.; Kalinicheva, Svetlana V.; Samsonova, Vera V.; Hiyama, Tetsuya; Iijima, Yoshihiro; Park, Hotaek; Iwahana, Go and Gorokhov, Alexey N. Mapping the main characteristics of permafrost on the basis of a permafrost-landscape map of Yakutia using GIS: Land (Basel), 10(5), Article 462, illus. incl. 4 tables, geol. sketch maps, 76 ref., May 2021. Part of a special issue entitled Permafrost landscape, edited by Federov, A.
The purpose of this article was to compile four separate digital thematic maps of temperature and ice content of permafrost, the active layer thickness, and cryogenic processes in Yakutia as a basis for assessing changes to modern climate changes and anthropogenic disturbances. In this work, materials on permafrost were used, serving as the basis for compiling a permafrost landscape map of the Republic of Sakha (Yakutia). The maps were compiled using ArcGIS software, which supports attribute table mapping. The ground temperature and active layer thickness maps reflected landscape zonality and regional differences. Peculiarities of genetic types of Quaternary deposits and climatic conditions reflected the ice content of surface sediments and cryogenic process distribution maps. One of the most common is ground temperatures from -2.1 to -4.0°C, which were found to occupy about 37.4% of the territory of Yakutia. More than half of the region was found to be occupied by permafrost landscapes with a limited thickness of the active layer up to 1.1 m. Ice-rich permafrost (more than 0.4 in ice content) was found to be typical for about 40% of the territory. Thermokarst is the most hazardous process that occurs in half of Yakutia.
DOI: 10.3390/land10050462
2022016045 Cheptsov, Vladimir S. (Lomonosov Moscow State University, Moscow, Russian Federation); Vorobyova, E. A.; Manucharova, N. A.; Gorlenko, M. V.; Pavlov, A. K.; Rozanova, M. S.; Lomasov, V. N.; Belov, A. A. and Chumikov, A. E. Prokaryotic community of the ancient Antarctic permafrost after irradiation with gamma rays under simulated Martian conditions: Eurasian Soil Science, 54(3), p. 417-423, illus. incl. 2 tables, 35 ref., March 2021.
Ionizing radiation is an important environmental factor affecting the dynamics of biospheric processes in the past and present, as well as limiting the spread of life outside the Earth. The effect of radiation on microorganisms has been studied for decades, but studies of the response of natural microbial ecosystems are still scarce. We have studied the effect of 100 kGy gamma irradiation under low pressure (1 Torr) and low temperature (-50°C) on microbial community of the ancient Antarctic permafrost sedimentary rock. After irradiation, the total number of prokaryotic cells determined by epifluorescence microscopy, as well as the number of metabolically active bacterial and archaeal cells detected by fluorescence in situ hybridization remained at the control level, while the number of cultured heterotrophic bacteria decreased by an order of magnitude. Using the multisubstrate testing method, it has been found that the microbial complex retained a high potential metabolic activity and functional diversity after exposure to a combination of extreme physical factors. The resistance demonstrated by the microbial community significantly exceeded the generally accepted estimates of the prokaryotes' radioresistance and indicated an underestimation of the microorganisms' radioresistance in natural habitats and the important role of mineral heterophase environment and irradiation conditions (pressure, temperature). The study confirmed the potential for long-term cryopreservation of viable terrestrial-like microorganisms in the Martian regolith, as well as the possibility of transferring anabiotic life forms as a part of small bodies in the space environment.
DOI: 10.1134/S1064229321030030
2022017175 Startsev, V. V. (Russian Academy of Sciences, Ural Branch, Komi Scientific Center, Syktyvkar, Russian Federation); Mazur, A. S. and Dymov, A. A. The content and composition of organic matter in soils of the Subpolar Urals: Eurasian Soil Science, 53(12), p. 1726-1734, illus. incl. 3 tables, 52 ref., December 2020.
Soil organic matter at high latitudes is an important and sensitive indicator of climate change. This article describes the main morphological features, chemical properties, and composition of organic matter in the main types of soils along the altitudinal gradient of the Subpolar Urals. Soils formed in the mountain tundra zone (gleyic humus-illuvial podbur/Skeletis Stagnic Entic Podzol (Turbic)), in the mountain subalpine zone (gray-humus soil/Skeletis Umbrisol), in the mountain taiga zone (iron-illuvial podzol/Skeletis Albic Podzol), and in the mountain tundra zone with permafrost (permafrost-affected gleyic humus-illuvial podbur/Skeletis Folic Cryosol (Humic)) were studied. The method of densimetric fractionation was applied to study soil organic matter; it enabled us to distinguish its three fractions, differing in carbon participation in the biological turnover: free particulate organic matter (fPOM<1.6), occluded particulate organic matter (oPOM<1.6), and heavy organic matter bound with the mineral phase (MaOM>1.6). The latter fraction dominated in the upper mineral soil horizons and comprised 89-93% of the total organic carbon. The content of light fractions was significantly lower (0.6-4.7%). However, the content of organic carbon and nitrogen in the studied soils directly correlated with the contents of light fractions fPOM<1.6 (r = 0.40 and r = 0.79, p < 0.05) and oPOM<1.6 (r = 0.68 and r = 0.83, p < 0.05). Aliphatic fragments dominated in the composition of POM; their content varied from 74.5 to 80.5% for fPOM<1.6 and from 77.9 to 84.2% for oPOM<1.6. In addition, it was found that the organic matter of the oPOM<1.6 fraction was characterized by a higher decomposition rate (0.4-2.4) and hydrophobicity (34.7-66.5%).
DOI: 10.1134/S106422932012011X
2022018876 Gu Jing (Nanjing University, School of Atmospheric Sciences, Nanjing, China); Pang Qiaotong; Ding Jinzhi; Yin Runsheng; Yang Yuanhe and Zhang Yanxu. The driving factors of mercury storage in the Tibetan grassland soils underlain by permafrost: Environmental Pollution (1987), 265(Part B), Article 115079, illus. incl. 1 table, sketch maps, 57 ref., October 2020. Includes appendix.
Soils, especially permafrost in the Arctic and the Tibetan Plateau, are one of the largest reservoirs of mercury (Hg) in the global environment. The Hg concentration in the grassland soils over the Tibetan Plateau and its driving factors have been less studied. This study analyzes soil total mercury (STHg) concentrations and its vertical distribution in grassland soil samples collected from the Tibetan Plateau. We adopt a nested-grid high-resolution GEOS-Chem model to simulate atmospheric Hg deposition. The relationship between STHg and soil organic carbon (SOC), as well as atmospheric deposition, are explored. Our results show that the STHg concentrations in the Tibetan Plateau are 19.8±12.2 ng/g. The concentrations are higher in the south and lower in the north in the Tibetan Plateau, consistent with the previous results. Our model shows that the average deposition flux of Hg is 3.3 mg m-2 yr-1, with 57% contributed by dry deposition of elemental mercury (Hg0), followed by dry (19%) and wet (24%) deposition of divalent mercury. We calculate the Hg to carbon ratio (RHg:C) as 5.6±6.5 mg Hg/g C, and the estimated STHg is 86.6±101.2 Gg in alpine grasslands in the Tibetan Plateau. We find a positive relationship between STHg and SOC in the Tibetan Plateau (r2=0.36) and a similar positive relationship between STHg and atmospheric total Hg deposition (r2=0.24). A multiple linear regression involving both variables better model the observed STHg (r2=0.42). We conclude that SOC and atmospheric deposition influence STHg simultaneously in this region. The data provides information to quantify the size of the soil Hg pool in the Tibetan Plateau further, which has important implications for the Hg cycles in the permafrost regions as well as on the global scale.
DOI: 10.1016/j.envpol.2020.115079
2022018843 Gubin, S. V. (Russian Academy of Sciences, Institute of Physicochemical and Biological Problems in Soil Science, Pushchino, Russian Federation) and Lupachev, A. V. Soils and sediments of the lacustrine-alas depressions in tundra zone of the Kolyma Lowland: Eurasian Soil Science, 53(7), p. 845-858, illus. incl. 4 tables, sketch map, 31 ref., July 2020.
Pedogenesis on the terraces of lacustrine-alas depressions in the tundra zone of the Kolyma Lowland takes place on sediments that are different in genesis but have significantly similar composition and properties. Soil morphology and soil cover patterns on terraces and slopes of depressions reflect the main trends of the Holocene pedogenesis and the rearrangement of the environment. On the terraces of the upper and middle levels, as well as on the interfluves, the major pedogenic trend is cryozem formation. On the lower terraces and in the bottoms of lacustrine-alas depressions, gleyzation and peat formation are considered to be stable and progressing processes. Soil formation is affected by close permafrost table (<1 m); therefore, all soils are qualified for Cryosols.
DOI: 10.1134/S1064229320070042
2022016032 Pavlova, N. A. (Russian Academy of Sciences, Siberian Branch, Melnikov Permafrost Institute, Yakutsk, Russian Federation); Shepelev, V. V.; Galanin, A. A. and Efremov, V. S. Groundwater hydrochemistry of suprapermafrost-intrapermafrost flow in their discharge areas in central Yakutia: Water Resources, 47(4), p. 581-590, illus. incl. 1 plate, 2 tables, sketch maps, 37 ref., July 2020.
The results of long-term studies of a group of aufeis-forming Buluus groundwater sources are given. A stow, which has been formed by the spring, contains the drainage area of the suprapermafrost-intrapermafrost aquifer, which is widespread in the sand deposits of the bestyakhskaya terrace of the Lena River in Central Yakutia. The analysis of observations of 1964-2017 showed stable water chemistry in Buluus spring at the long-term scale. Considerable seasonal variations of water chemistry are typical of low-discharge springs, which start functioning after becoming free of aufeis. The spring water also shows higher concentrations of lithium and fluorine. The possible causes of the different chemistry of spring water are discussed, with special attention paid to the local activity of rock freezing and thawing processes in the aufeis valley. It is shown that groundwater samples are to be taken from all springs in the areas of their group discharge with the aim to assess the effect of natural and technogenic factors on the permafrost-hydrogeochemical conditions.
DOI: 10.1134/S0097807820040119
2022017081 Khudyakov, O. I. (Russian Academy of Sciences, Institute of Physicochemical and Biological Problems of Soil Science, Pushchino, Russian Federation) and Reshotkin, O. V. Multidirectional changes in temperature of permafrost-affected soils during the growing season against the background increase in the mean annual air temperature: Eurasian Soil Science, 53(5), p. 607-618, illus. incl. 2 tables, 34 ref., May 2020.
Data on air and soil temperatures at the Verkhoyansk and Oymyakon weather stations in the East Siberian permafrost-taiga region are analyzed. The soils are represented by permafrost-affected sandy podzolized podbur (Verkhoyansk) and loamy soddy soil (Oymyakon). Recent decades have been the period of steady warming; average annual air temperature in 2001-2010 exceeded the climatological normal (1961-1990) by 1.4-1.5°C. An increase in air temperature is observed both in the cold and warm seasons. The temperature response of sandy and loamy soils to this warming is different. In the cold season, both soils are characterized by some rise in temperatures. In the warm season, the sandy soil demonstrates an increase in temperature and in the seasonal thawing depth, whereas the loamy soil is characterized by some a decrease in temperature and in the thawing depth. The importance of the snow cover as a factor slowing down soil freezing in the fall and soil thawing in the spring is demonstrated. The soil water and ice contents are also important factors affecting soil temperatures. It is shown that the freezing of both soils and their preservation in the frozen state take place at temperatures established at the snow/soil contact. In the coldest month (January), these temperatures in Verkhoyansk and Oymyakon are 12.6 and 14.3°C higher than air temperatures and 14.9 and 16.0°C higher than temperatures at the surface of the snow cover, respectively. The decrease in summer temperatures of the permafrost-affected loamy soil is explained by a higher heat consumption for the ice-water phase transition during the soil thawing.
DOI: 10.1134/S1064229320050075
2022017077 Okoneshnikova, M. V. (Russian Academy of Science, Siberian Branch, Institute for Biological Problems of the Cryolithozone, Yakutsk, Russian Federation); Ivanova, A. Z. and Desyatkin, R. V. Soils of the Verkhoyansk Range in the area of Arkachan Plateau: Eurasian Soil Science, 53(5), p. 535-543, illus. incl. 4 tables, sketch map, 28 ref., May 2020.
The vertical zonality of the soil cover of the Verkhoyansk mountainous soil province is discussed. The soils of the landscape-ecological profile in the area of the Arkachan Plateau (65°N, 130°E) have been studied. Their morphogenetic characteristics and position in the new Russian soil classification system are analyzed. The absolute height of the mountains reaches 1200 m, the relative height ranges from 400 to 500 m. The plateau is composed of sandstone, siltstone, and shale of the Mesozoic age. The climate is cold and sharply continental. Permafrost has a continuous character. However, in the profile of mountainous soils, permafrost is often absent, as its upper table lies below the stony soil profile. In the vertical zonality of the Arkachan Plateau, mountainous tundra zone (>1100 m a.s.l.) and mountainous taiga zone (<1000 m a.s.l.) predominate and are characterized by the development of lithozems (Leptosols), peat lithozems (Cryic Epirockic Histosols), and mucky lithozems (Eutric Histic Skeletic Leptosols). On the terraces of mountain rivers, thin gleyic cryozems (Turbic Cryosols) are formed; stony peat gleyzems (Histic Reductaquic Cryosols) are found in accumulative zones on slopes, and gray-humus alluvial soils (Skeletic Leptosols) are developed on the floodplains. Thin profiles, peaty and raw-humus organic horizons, stoniness, acid or slightly acid reaction, low base saturation in topsoil horizons, and weakly pronounced morphological and physicochemical differentiation of the profile are typical of all the studied soils. The results of this study can be used to develop the database on poorly studied soils of mountainous areas and their characteristic features.
DOI: 10.1134/S1064229320050105
2022015997 Liu Ziying (Northeast Forestry University, College of Civil Engineering, Xiangfang, China); Yu Tianlai; Yan Ning and Gu Lipeng. Variation of ground temperature along the stratum depth in ice rich tundra of Hinggan Mountains region, NE China: Geosciences (Basel), 10(3), Article 104, illus. incl. geol. sketch map, 29 ref., March 2020.
A pile foundation in a permafrost region is in a negative-temperature environment, so concrete is affected by the negative temperature of the surrounding soil. It not only affects the formation of concrete strength but also leads to engineering quality accidents in serious cases. With the support of the two permafrost bridge projects of the national highway from Beijing to Mohe in the Greater Khingan Mountains region, a systematic remote dynamic monitoring method for ground temperature in ice-rich tundra is proposed. Based on the actual measurement of temperature at different strata depths and the comprehensive consideration of surface temperature, terrestrial heat flux and other parameters, the ground temperature profile evolution in relation to depth in Greater Khingan was established. The theoretical ground temperature profile curve is similar to the measured profile. The results show that the variation trends of ground temperatures in relation to the strata depth at different monitoring sites is similar, and all show seasonal variation: From June to November, the ground temperature at different depths tends to be constant. From December to May, the ground temperature at any depth within the range of 0 to 5.5 m follows the curve of the cosine function. Below 5.5 m, the earth temperature no longer varies with depth. The research results can be used as reference for pile foundation construction in a negative-temperature environment in ice-rich tundra.
DOI: 10.3390/geosciences10030104
2022018766 Bolikhovskaya, N. S. (Lomonosov Moscow State University, Faculty of Geography, Moscow, Russian Federation) and Makshaev, R. R. The early Khvalynian Stage in the Caspian Sea evolution; pollen records, palynofloras and reconstructions of paleoenvironments: in INQUA focus group SACCOM; 1709 "Ponto-Caspian stratigraphy and geochronology (POCAS)" (Hombach-Yanko, Valentina, editor), Quaternary International, 540, p. 10-21, illus. incl. sketch map, 2 tables, strat. col., 49 ref., February 25, 2020.
In addressing the controversial issues of the Late Pleistocene paleogeography of the Caspian basin, an important role is given to the results of the spore-pollen analysis and based on them reconstructions of climate and vegetation changes in the Northern Caspian region during the development of the Early Khvalynian transgression. In this paper we present the main results of the palynological study of deposits (chocolate clays and the overlying and underlying layers from the Srednyaya Akhtuba section) of maximum stage of the Early Khvalynian transgression; the materials are illustrated by pollen diagram with the data of spore-pollen analysis and the detailed list of palynoflora recovered from the studied Lower Khvalynian sequences, and complemented with photographs of pollen belonging to the principal autochtonous taxa and, for comparison, to some redeposited palynomorphs. Palynological materials indicate subaqual (brackish marine and freshwater) sedimentation of the sediments studied in periglacial landscapes and, for the most part, under very harsh climatic conditions. The performed climate-stratigraphic reconstructions do not contradict the data of absolute dating on the accumulation of the studied deposits during the Late Valdai (Ostashkov) late Glacial period. During this interval in the territory of the study area, plant communities of the glacial climate - tundra-steppe, periglacial forest-steppe, periglacial steppe, periglacial parklands and periglacial forests - were developed. The widespread occurrence in the composition of the periglacial vegetation cover of the studied region of the yernik formations from Betula nana and shrub communities from Betula fruticosa, B. nana, Alnaster fruticosus, Juniperus, etc. testifies to the severe climatic conditions and, possibly, the existence of sporadic permafrost in the cold stages (stadials) of the Ostashkov Late Glacial period.
DOI: 10.1016/j.quaint.2019.11.012
2022015930 Debol'skaya, E. I. (Russian Academy of Sciences, Water Problems Institute, Moscow, Russian Federation) and Ivanov, A. V. Comparative analysis of models of thermoerosion-induced channel deformations in rivers of permafrost zone: Water Resources, 47(1), p. 77-86, illus., 36 ref., January 2020.
Studies of erosion processes in river channels of the permafrost zone are reviewed. Mathematical models of thermal erosion and the deformations it induces are discussed in different formulations; the results of numerical calculations by two models are compared with one another and with laboratory measurement data. The major factors that have an effect on channel transformations in permafrost-zone rivers are identified.
DOI: 10.1134/S0097807820010054
2022019251 Verret, M. (Victoria University of Wellington, Antarctic Research Centre, Wellington, New Zealand); Dickinson, W.; Lacelle, D.; Fisher, D.; Norton, K.; Chorley, H.; Levy, R. H. and Naish, T. R. Cryostratigraphy of mid-Miocene permafrost at Friis Hills, McMurdo Dry Valleys of Antarctica: Antarctic Science, 33(2), p. 174-188, illus. incl. 2 tables, 46 ref., 2020.
The origin and stability of ground ice in the stable uplands of the McMurdo Dry Valleys remains poorly understood, with most studies focusing on the near-surface permafrost. The 2016 Friis Hills Drilling Project retrieved five cores reaching 50 m depth in mid-Miocene permafrost, a period when Antarctica transitioned to a hyper-arid environment. This study characterizes the cryostratigraphy of arguably the oldest permafrost on Earth and assesses 15 Myr of ground ice evolution using the REGO model. Four cryostratigraphic units were identified: 1) surficial dry permafrost (0-30 cm), 2) ice-rich to ice-poor permafrost (0.3-5.0 m) with high solute load and and d18O values (-16.2 ± 1.8ppm) and low D-excess values (-65.6 ± 4.3ppm), 3) near-dry permafrost (5-20 m) and 4) ice-poor to ice-rich permafrost (20-50 m) containing ice lenses with low solute load and d18O values (-34.6 ± 1.2ppm) and D-excess of 6.9 ± 2.6ppm. The near-surface d18O profile of ground ice is comparable to other sites in the stable uplands, suggesting that this ice is actively responding to changing surface environmental conditions and challenging the assumption that the surface has remained frozen for 13.8 Myr. The deep ice lenses probably originate from the freezing of meteoric water during the mid-Miocene, and their d18O composition suggests mean annual air temperatures ~7-11°C warmer than today.
DOI: 10.1017/S0954102020000619
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The USPA is pleased to announce the availability of an updated searchable database on permafrost-related publications. The American Geosciences Institute (AGI), with support from the National Science Foundation (NSF), has migrated the previous Cold Regions Bibliography to a new platform. Included are the USPA supported PMAs dating back to 2011. The Bibliography is searchable at 
