Permafrost Monthly Alerts (PMAs)

2016035829 Guo, Y. D. (Chinese Academy of Sciences, Northeast Institute of Geography and Agroecology, Changchun, China); Song, C. C.; Wan, Z. M.; Lu, Y. Z.; Qiao, T. H.; Tan, W. W. and Wang, L. L. Dynamics of dissolved organic carbon release from a permafrost wetland catchment in northeast China: Journal of Hydrology, 531(Part 3), p. 919-928, illus. incl. 5 tables, sketch map, 48 ref., December 2015.

A large reservoir of organic carbon is stored in the permafrost region. Therefore, understanding the export of dissolved organic carbon (DOC) from rivers in the permafrost zone is important in the context of climate change. This study investigated the dynamics of DOC export from the wetlands of the Kandu River catchment located in a cold temperate region in northeast China during the growing seasons of 2011 and 2012. Our findings indicated that subsurface flow was the primary runoff pathway that transports DOC from wetland soil to stream discharge. The organic-mineral soil structure resulted in substantial differences in water sources, as well as in DOC resources, between the flood and base flow volume during the growing seasons. The active layer depth is key, as it affects runoff generation and the DOC concentration and chemical characteristics of stream discharge. The DOC flux from our study area was estimated to be up to 1039.66 t during the growing season, which represents more than one third of the net ecosystem exchange (NEE) in wetlands. Given the expected increase in air temperature and precipitation, our results indicate that there will be an increase in the total DOC flux for the study region in the future as a result of increased DOC concentration. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.jhydrol.2015.10.008

2016032235 Höfle, Silke T. (University of Cologne, Institute of Geology and Mineralogy, Cologne, Germany); Kusch, Stephanie; Talbot, Helen M.; Mollenhauer, Gesine; Zubrzycki, Sebastian; Burghardt, Sophia and Rethemeyer, Janet. Characterisation of bacterial populations in Arctic permafrost soils using bacteriohopanepolyols: Organic Geochemistry, 88, p. 1-16, illus. incl. 5 tables, 105 ref., November 2015. Includes appendices.

Bacteriohopanepolyols (BHPs) are biomarkers providing taxonomically and environmentally diagnostic information. BHPs may help to unravel the composition of bacterial communities residing in recent as well as ancient permafrost soils and sediments and also provide information on associated environmental conditions. However, detailed data on their distribution in the heterogeneous Arctic environment are scarce. The distribution and structural diversity of BHPs were studied in the annually thawing (active) layer of three different sites in the polygonal tundra of the Lena Delta in the Siberian Arctic. Variations between permafrost structures and soil horizons caused by differences in the physical and chemical soil properties were observed. C and N content is significantly correlated with the BHP composition so that the highest BHP concentrations and greatest structural diversity occur in the uppermost organic soil horizons, which consist mainly of fresh or little degraded plant material. Furthermore, statistical analyses reveal that higher abundances of adenosylhopane-type soil marker BHPs are linked to higher soil pH values. Small scale environmental controls on BHP distributions are reflected by amine-functionalised BHPs from methanotrophic bacteria only occurring in the water-saturated, oxygen-depleted polygon centres and by soil marker BHPs, which are significantly more abundant in the well aerated polygon rims than in the centres. In contrast, C-2 methylated BHPs, putative indicators of plant-bacterial interactions, are present in all soil horizons and permafrost structures and their relative distribution is not systematically linked to soil properties. Overall, lipid-based results agree with published 16S rRNA based community structure assessments highlighting the usefulness of BHPs to represent bacterial populations in recent and ancient permafrost soils. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.orggeochem.2015.08.002

2016032313 Chang Juan (Lanzhou University, College of Earth and Environment Science, Lanzhou, China); Wang Genxu and Mao Tianxu. Simulation and prediction of suprapermafrost ground water level variation in response to climate change using a neural network model: Journal of Hydrology, 529(Part 3), p. 1211-1220, illus. incl. 5 tables, sketch map, 41 ref., October 2015.

Suprapermafrost groundwater has an important role in the hydrologic cycle of the permafrost region. However, due to the notably harsh environmental conditions, there is little field monitoring data of groundwater systems, which has limited our understanding of permafrost groundwater dynamics. There is still no effective mathematical method and theory to be used for modeling and forecasting the variation in the permafrost groundwater. Two ANN models, one with three input variables (previous groundwater level, temperature and precipitation) and another with two input variables (temperature and precipitation only), were developed to simulate and predict the site-specific suprapermafrost groundwater level on the slope scale. The results indicate that the three input variable ANN model has superior real-time site-specific prediction capability and produces excellent accuracy performance in the simulation and forecasting of the variation in the suprapermafrost groundwater level. However, if there are no field observations of the suprapermafrost groundwater level, the ANN model developed using only the two input variables of the accessible climate data also has good accuracy and high validity in simulating and forecasting the suprapermafrost groundwater level variation to overcome the data limitations and parameter uncertainty. Under scenarios of the temperature increasing by 0.5 or 1.0 °C per 10 years, the suprapermafrost groundwater level is predicted to increase by 1.2-1.4% or 2.5-2.6% per year with precipitation increases of 10-20%, respectively. There were spatial variations in the responses of the suprapermafrost groundwater level to climate change on the slope scale. The variation ratio and the amplitude of the suprapermafrost groundwater level downslope are larger than those on the upper slope under climate warming. The obvious vulnerability and spatial variability of the suprapermafrost groundwater to climate change will impose intensive effects on the water cycle and alpine ecosystems in the permafrost region. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.jhydrol.2015.09.038

2016032177 Pirk, Norbert (Lund University, Department of Physical Geography and Ecosystem Science, Lund, Sweden); Santos, Telmo; Gustafson, Carl; Johansson, Anders J.; Tufvesson, Fredrik; Parmentier, Frans-Jan W.; Mastepanov, Mikhail and Christensen, Torben R. Methane emission bursts from permafrost environments during autumn freeze-in; new insights from ground-penetrating radar: Geophysical Research Letters, 42(16), p. 6732-6738, illus., 30 ref., August 28, 2015.

Large amounts of methane (CH₄) are known to be emitted from permafrost environments during the autumn freeze-in, but the specific soil conditions leading up to these bursts are unclear. Therefore, we used an ultrawide band ground-penetrating radar in Northeast Greenland in autumn 2009 to estimate the volumetric composition inside the soil through dielectric characterization from 200 to 3200 MHz. Our results suggest a compression of the gas reservoir during the phase transition of soil water, which is accompanied by a peak in surface CH₄ emissions. About 1 week thereafter, there seems to be a decompression event, consistent with ground cracking which allows the gas reservoir to expand again. This coincides with the largest CH₄ emission, exceeding the summer maximum by a factor of 4. We argue that these complementary measurement techniques are needed to come to an understanding of tundra CH₄ bursts connected to soil freezing. Abstract Copyright (2015), The Authors.

DOI: 10.1002/2015GL065034

2016033044 Swarzenski, Peter W. (U. S. Geological Survey, Santa Cruz, CA); Johnson, Cordell D.; Lorenson, Tom D.; Conaway, Christopher H.; Gibbs, Ann E.; Erikson, Li H.; Richmond, Bruce M. and Waldrop, Mark P. Seasonal electrical resistivity surveys of a coastal bluff, Barter Island, North Slope, Alaska: Journal of Environmental & Engineering Geophysics, 21(1), p. 37-42, illus., 32 ref., 2016.

Select coastal regions of the North Slope of Alaska are experiencing high erosion rates that can be attributed in part to recent warming trends and associated increased storm intensity and frequency. The upper sediment column of the coastal North Slope of Alaska can be described as continuous permafrost underlying a thin (typically less than 1-2 m) active layer that responds variably to seasonal thaw cycles. Assessing the temporal and spatial variability of the active layer and underlying permafrost is essential to better constrain how heightened erosion may impact material fluxes to the atmosphere and the coastal ocean, and how enhanced thaw cycles may impact the stability of the coastal bluffs. In this study, multi-channel electrical resistivity tomography (ERT) was used to image shallow subsurface features of a coastal bluff west of Kaktovik, on Barter Island, northeast Alaska. A comparison of a suite of paired resistivity surveys conducted in early and late summer 2014 provided detailed information on how the active layer and permafrost are impacted during the short Arctic summer. Such results are useful in the development of coastal resilience models that tie together fluvial, terrestrial, climatic, geologic, and oceanographic forcings on shoreline stability.

DOI: 10.2113/JEEG21.1.37

2016033067 Malov, A. I. (Russian Academy of Sciences, Ural Branch, Institute of Environmental Problems of the North, Arkhangelsk, Russian Federation); Bolotov, I. N.; Pokrovsky, O. S.; Zykov, S. B.; Tokarev, I. V.; Arslanov, Kh. A.; Druzhinin, S. V.; Lyubas, A. A.; Gofarov, M. Y.; Kostikova, I. A.; Kriauciunas, V. V.; Chernov, S. B.; Maksimov, F. E.; Bespalaya, Yu. V. and Aksenova, O. V. Modeling past and present activity of a subarctic hydrothermal system using O, H, C, U and Th isotopes: Applied Geochemistry, 63, p. 93-104, illus. incl. 4 tables, geol. sketch map, 67 ref., December 2015. Includes appendices.

The hot springs of the Pymvashor subarctic hydrothermal system are of considerable interest because the area is devoid of recent volcanism and is located in the permafrost region. We attempted to evaluate the activity of thermal waters with respect to host rocks to quantify the water residence time in this system and date the associated travertine. Therefore, we used the chemical composition of the thermal waters, thermodynamic modeling, d¹⁸O and d²H labels and isotopes, such as ¹⁴C-d¹³C, ²³⁴U-²³⁸U, and ²³⁰Th-²³²Th. The d¹⁸O and d²H values indicated the infiltration of atmospheric water in the recharge area of the hydrothermal system and suggested a stable paleoclimate in the area over the last 5-7.9 thousand years. The fresh water flows through deep parts of the aquifer system where it mixes with brine followed by discharge. The hot springs geothermal water total dissolved solid (TDS) ranged from 1.8 to 2 g/L, and in the deep wells, the TDS ranged from 7.1 to 198 g/L. The ratios of Na/Cl (mol), Br/10^-3Cl (ppm), and Ca/Cl (ppm) in the thermal springs ranged from 0.89 to 0.90, 1.8 to 1.9, and close to 0.12, respectively, reflecting participation of deep brines in their formation. The composition of the thermal water can be formed via a mixture of one part of the brines with 130 parts of the cold water end member with a TDS of 291 mg/L. The results of thermodynamic modeling and mixing diagram analysis indicate that during water-rock interaction in the aquifer, the precipitation of calcite and the dissolution of gypsum and magnesite were accompanied by hydrolysis of the sodium aluminosilicates with precipitating clay secondary minerals. The low uranium concentration in the Pymvashor groundwater (0.24-0.34 ppb) and the sufficiently long water residence time combined with the relatively high ²³⁴U/²³⁸U activity ratios (3-5) suggest a high a recoil loss and low dissolution rates of the host rocks or a high precipitation rate and adsorption of uranium. The elevated values of the a recoil loss may be due to radioactive decay of the precipitated and adsorbed ²³⁸U because in this case, the probability of ²³⁴Th release and ²³⁴U appearance in water increases ~4-fold compared to the probability of emission directly from the rock. The ¹⁴C age of the water was estimated to be between 4960 and 7870 years, and the ²³⁰Th/U age of the travertine ranged from 1970 to 7650 years. Overall, these results allow for a better understanding of the nature and evolution of the thermal waters in this unique subarctic hydrothermal system. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.apgeochem.2015.07.003

2016035752 Scribner, C. A. (University of Florida, Department of Geological Sciences, Gainesville, FL); Martin, E. E.; Martin, J. B.; Deuerling, K. M.; Collazo, D. F. and Marshall, A. T. Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland: Geochimica et Cosmochimica Acta, 170, p. 157-172, illus. incl. 1 table, sketch map, 73 ref., December 1, 2015. Includes appendices.

Fine-grained sediments deposited by retreating glaciers weather faster than the global average and this weathering can impact the global carbon cycle and oceanic fluxes of nutrients and radiogenic isotopes. Much work has focused on subglacial and proglacial weathering of continental ice sheets, but little is known about weathering and resulting fluxes from deglacial watersheds, which are disconnected from the ice sheets and discharge only annual precipitation and permafrost melt. We investigate the effects of exposure age and precipitation on weathering intensity in four deglacial watersheds on Greenland that form a transect from the coast near Sisimiut toward the Greenland Ice Sheet (GrIS) near Kangerlussuaq based on evaluations of major ion compositions, Sr isotope ratios, and mineral saturation states of waters and sediments. The transect is underlain by Archean orthogneiss and is characterized by gradients in moraine ages (~7.5-8.0 ky inland to ~10 ky at the coast) and water balance (-150 mm/yr inland to +150 mm/yr at the coast). Anion compositions are generally dominated by HCO₃, but SO₄ becomes increasingly important toward the coast, reflecting a switch from trace carbonate dissolution to sulfide mineral oxidation. Coastal watersheds have a higher proportion of dissolved silica, higher Na/Cl, Si/Ca, and lower Ca/Sr ratios than inland watersheds, indicating an increase in the relative proportion of silicate weathering and an increase in the extent of weathering toward the coast. More extensive weathering near the coast is also apparent in differences in the ⁸⁷Sr/⁸⁶Sr ratios of stream water and bedload (D⁸⁷Sr/⁸⁶Sr), which decreases from 0.017 inland to 0.005 at the coast, and in increased saturation states relative to amorphous SiO₂ and quartz. The steep weathering gradient from inland to coastal watersheds reflects enhanced weathering compared to that expected from the 2 to 3 ky difference in exposure age caused by elevated coastal precipitation. The gradient of weathering with exposure age, water budget and distance from the ice sheet indicates that oceanic and atmospheric fluxes will change as continental glaciers retreat, precipitation patterns across the deglacial region readjust, and the relative proportion of deglacial to proglacial runoff increases. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.gca.2015.08.008

2016034176 Mason, Joseph A. (University of Wisconsin, Department of Geography, Madison, WI). Up in the refrigerator; geomorphic response to periglacial environments in the upper Mississippi River basin, USA: Geomorphology, 248, p. 363-381, illus. incl. sketch maps, 141 ref., November 1, 2015.

James C. Knox was best-known for his work on Holocene and historical changes in fluvial systems, but he also had a long-standing interest in the effects of late Pleistocene periglacial environments on landscape evolution in parts of the Upper Mississippi River basin that were just outside the Laurentide Ice Sheet margin, or as Knox put it, 'up in the refrigerator.' Knox and others in the Quaternary community of the Midwestern U.S. often suggested that hillslope erosion was accelerated under periglacial conditions, so that glacial periods have had a dominant effect on the landscape we see today. This paper reviews the evidence and reasoning supporting that view in a study area of the Upper Mississippi basin bordered on three sides by ice margins of the last glaciation, including the Wisconsin Driftless Area and adjacent landscapes. Sparse but compelling paleoecological data and relict ice- or sand-wedge polygons provide clear evidence for a cold climate and widespread permafrost around the peak of the last glaciation. In highly dissected, relatively high-relief parts of the study area, the loess and soil stratigraphy on ridgetops and the colluvial mantles on steeper slopes are best explained by highly effective hillslope erosion, including solifluction, during and just after the Last Glacial Maximum. Knox used the post-depositional truncation of a loess unit to quantify contrasting late Pleistocene and Holocene sediment yields from a small Driftless Area watershed. While the late Pleistocene yield indicates accelerated erosion, it is still lower than modern sediment yields in many tectonically active or semiarid landscapes, and it may reflect deposition of highly erodible loess as well as effects of periglacial conditions. The views of Knox and other Midwestern geomorphologists on landscape evolution through glacial-interglacial cycles were highly influenced by the work of Robert V. Ruhe. Ruhe proposed that an episode of widespread erosion during and just after the Last Glacial Maximum can explain enigmatic aspects of Quaternary stratigraphy and the soil landscape on the Iowan Erosion Surface, a very low relief landscape of the study area. Ruhe's key evidence is still valid, though it needs to be separated from an implausible model of landscape evolution. Interpretation of the Iowan Erosion Surface and other low-relief landscapes just outside the ice margin also requires recognition of the profound effect of eolian processes on those landscapes under periglacial conditions. Many new insights on landscape evolution in the study area could result from wider application of cosmogenic nuclide-based methods to assess glacial-interglacial changes in basinwide rates of erosion and residence time of soils. Just as important, a need exists for much more field-based characterization of hillslope, fluvial, and eolian sediments for comparison with those of modern permafrost regions and past periglacial environments in Europe. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.geomorph.2015.08.004

2016032180 Cuo Lan (Chinese Academy of Sciences, Institute of Tibetan Plateau Research, Beijing, China); Zhang, Yongxin; Bohn, Theodore J.; Zhao Lin; Li Jialuo; Liu Qiming and Zhou Bingrong. Frozen soil degradation and its effects on surface hydrology in the northern Tibetan Plateau: Journal of Geophysical Research: Atmospheres, 120(16), p. 8276-8298, illus. incl. 2 tables, sketch map, 40 ref., August 27, 2015.

Frozen soil was simulated at six seasonally frozen and seven permafrost stations over the northern Tibetan Plateau using the Variable Infiltration Capacity (VIC) model for the period of 1962-2009. The VIC model resolved the seasonal cycle and temporal evolution of the observed soil temperatures and liquid soil moisture well. The simulated long-term changes during 1962-2009 indicated mostly positive trends for both soil temperature and soil moisture, and negative trends for soil ice content at annual and monthly time scales, although differences existed among the stations, soil layers, and seasons. Increases in soil temperature were due mainly to increases in daily air temperature maxima and internal soil heat conduction, while decreases in soil ice content were related to the warming of frozen soil. For liquid soil moisture, increases in the cold months can be attributed to increases in soil temperature and enhanced soil ice melt while changes in the warm months were the results of competition between positive precipitation and negative soil temperature effects. Precipitation and liquid soil moisture were strongly correlated with evapotranspiration and runoff but had various degrees of correlations with base flow during May-September. Seasonally frozen stations displayed longer and more active hydrological processes than permafrost stations. Slight enhancement of the surface hydrological processes at the study stations was indicated, due to the combined effects of precipitation changes, which were dominant, and frozen soil degradation. Abstract Copyright (2015), American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2015JD023193

2016031708 Guo Donglin (Chinese Academy of Sciences, Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Beijing, China) and Wang Huijun. Simulated change in the near-surface soil freeze/thaw cycle on the Tibetan Plateau from 1981 to 2010: Chinese Science Bulletin, 59(20), p. 2439-2448, 37 ref., July 2014. Based on Publisher-supplied data.

The near-surface freeze/thaw cycle in cold regions plays a major role in the surface energy budget, hydrological activity, and terrestrial ecosystems. In this study, the Community Land Model, Version 4 and a suite of high-resolution atmospheric data were used to investigate the changes in the near-surface soil freeze/thaw cycle in response to the warming on the Tibetan Plateau from 1981 to 2010. The in situ observations-based validation showed that, considering the cause of scale mismatch in the comparison, the simulated soil temperature, freeze start and end dates, and freeze duration at the near-surface were reasonable. In response to the warming of the Tibetan Plateau at a rate of approximately 0.44 °C decade^-1, the freeze start-date became delayed at an area-mean rate of 1.7 days decade^-1, while the freeze end-date became advanced at an area-mean rate of 4.7 days decade^-1. The delaying of the freeze start-date, which was combined with the advancing of the freeze end-date, resulted in a statistically significant shortening trend with respect to the freeze duration, at an area-mean rate of 6.4 days decade^-1. Such changes would strongly affect the surface energy flux, hydrological processes, and vegetation dynamics. We also found that the rate of freeze-duration shortening at the near-surface soil layer was approximately 3.0 days decade^-1 lower than that at a depth of 1 m. This implied that the changes in soil freeze/thaw cycles at the near surface cannot be assumed to reflect the situation in deeper soil layers. The significant correlations between freeze duration and air temperature indicated that the shortening of the near-surface freeze duration was caused by the rise in air temperature, which occurred especially in spring, followed by autumn. These results can be used to reveal the laws governing the response of the near-surface freeze/thaw cycle to climate change and indicate related changes in permafrost. Copyright 2014 Science China Press and Springer-Verlag Berlin Heidelberg

DOI: 10.1007/s11434-014-0347-x

2016034233 Lauretano, V. (Utrecht University, Department of Earth Sciences, Utrecht, Netherlands); Littler, K.; Polling, M.; Zachos, J. C. and Lourens, L. J. Frequency, magnitude and character of hyperthermal events at the onset of the Early Eocene Climatic Optimum: Climate of the Past, 11(10), p. 1313-1324, illus. incl. 2 tables, sketch map, 53 ref., 2015.

Recent studies have shown that the Early Eocene Climatic Optimum (EECO) was preceded by a series of short-lived global warming events, known as hyperthermals. Here we present high-resolution benthic stable carbon and oxygen isotope records from ODP Sites 1262 and 1263 (Walvis Ridge, SE Atlantic) between ~ 54 and ~ 52 million years ago, tightly constraining the character, timing, and magnitude of six prominent hyperthermal events. These events, which include Eocene Thermal Maximum (ETM) 2 and 3, are studied in relation to orbital forcing and long-term trends. Our findings reveal an almost linear relationship between d¹³C and d¹⁸O for all these hyperthermals, indicating that the eccentricity-paced covariance between deep-sea temperature changes and extreme perturbations in the exogenic carbon pool persisted during these events towards the onset of the EECO, in accordance with previous observations for the Paleocene Eocene Thermal Maximum (PETM) and ETM2. The covariance of d¹³C and d¹⁸O during H2 and I2, which are the second pulses of the "paired" hyperthermal events ETM2-H2 and I1-I2, deviates with respect to the other events. We hypothesize that this could relate to a relatively higher contribution of an isotopically heavier source of carbon, such as peat or permafrost, and/or to climate feedbacks/local changes in circulation. Finally, the d¹⁸O records of the two sites show a systematic offset with on average 0.2 per mil heavier values for the shallower Site 1263, which we link to a slightly heavier isotopic composition of the intermediate water mass reaching the northeastern flank of the Walvis Ridge compared to that of the deeper northwestern water mass at Site 1262.

URL: http://www.clim-past.net/11/1313/2015/cp-11-1313-2015.pdf

2016030072 Murton, Julian B. (University of Sussex, Department of Geography, Brighton, United Kingdom); Goslar, Tomasz; Edwards, Mary E.; Bateman, Mark D.; Danilov, Petr P.; Savvinov, Grigoriy N.; Gubin, Stanislav V.; Ghaleb, Bassam; Haile, James; Kanevskiy, Mikhail; Lozhkin, Anatoly V.; Lupachev, Alexei V.; Murton, Della K.; Shur, Yuri; Tikhonov, Alexei; Vasil'chuk, Alla C.; Vasil'chuk, Yurij K. and Wolfe, Stephen A. Palaeoenvironmental interpretation of yedoma silt (ice complex) deposition as cold-climate loess, Duvanny Yar, northeast Siberia: Permafrost and Periglacial Processes, 26(3), p. 208-288, illus. incl. strat. cols., 7 tables, sketch maps, 300 ref., September 2015.

URL: http://onlinelibrary.wiley.com/doi/10.1002/ppp.1843/epdf

2016030036 Nakatsubo, Takayuki (Hiroshima University, Department of Environmental Dynamics and Management, Hiroshima, Japan); Uchida, Masaki; Sasaki, Akiko; Kondo, Miyuki; Yoshitake, Shinpei and Kanda, Hiroshi. Carbon accumulation rate of peatland in the High Arctic, Svalbard; implications for carbon sequestration: Polar Science, 9(2), p. 267-275, illus. incl. 5 tables, sketch map, 22 ref., June 2015.

Moss tundra that accumulates a thick peat layer is one of the most important ecosystems in the High Arctic, Svalbard. The importance of this ecosystem for carbon sequestration was estimated from the apparent rates of carbon accumulation based on the 14C age and amount of peat in the active layer. The study site at Stuphallet, Brogger Peninsula, northwestern Svalbard was covered with a thick peat layer dominated by moss species such as Calliergon richardsonii, Paludella squarrosa, Tomenthypnum nitens, and Warnstorfia exannulata. The average thickness of the active layer (brown moss and peat) was approximately 28 cm in 1 August 2011. The calibrated (cal) age of peat from the bottom of the active layer (20-30 cm below the peatland surface) ranged from 81 to 701 cal yr BP (median value of 2? range). Based on the total carbon (4.5-9.2 kg C m^-2), the apparent rate of carbon accumulation in the active layer was 9.0-19.2 (g C m^-2 yr^-1), which is similar to or greater than the net ecosystem production or net primary production reported for other vegetation types in this area. Our data suggest that moss tundra plays an important role in carbon sequestration in this area.

DOI: 10.1016/j.polar.2014.12.002

2016035663 Osokin, N. I. (Russian Academy of Sciences, Institute of Geography, Moscow, Russian Federation); Sosnovskiy, Aleksandr V. and Nakalov, P. R. O vliyanii izmenchivosti parametrov snezhnogo pokrova na promerzaniye grunta [Influence of snowpack parameter variations on ground freezing]: Led i Sneg = Ice and Snow, 130, p. 60-68 (English sum.), illus. incl. 2 tables, 12 ref., 2015.

Depth and rate of the soil freezing are strongly determined by dynamics of snow accumulation during the first half of a cold season. One of characteristics of dynamics of the snow cover thickness is a ratio a of the snow cover height for the period until January 1st to the maximum of snow cover thickness for the whole season. Analysis of this relationship calculated from data of snow surveys for two periods (2001-2010) and (1966-2000) allowed revealing that in the European part of Russia and in basin of the river Ob the ratio a decreased by 20-40% during the last decade while in some areas of West Yakutia and in basin of the Yenisei River it decreased by only 15%. This results in increasing of the soil freezing depth and thus compensates the air temperature rise. In areas located to the East of the Lena river, near the Baikal, and in the river Indigirka basin proportion of solid precipitation until January 1st increased by 10-20%. Maximal values of the ratio a during the period of 1966-2010 varied from 0.7 to 1, while the minimal values--from very low to 0.65. Model calculations did show that differences in the soil freezing depths under different conditions of snow cover growth sometimes exceeded 50%. With low thickness of snow cover its interannual fluctuations determine dynamics of minimal soil temperature at the depth of 320 cm. Interannual variability of the snow cover thermal resistance is also presented.

DOI: 10.15356/2076-6734-2015-2-60-68

2016032338 Dragon, Krzysztof (Adam Mickiewicz University, Institute of Geology, Poznan, Poland); Marciniak, Marek; Szpikowski, Jozef; Szpikowska, Grazyna and Wawrzyniak, Tomasz. The hydrochemistry of glacial Ebba River (Petunia Bay, central Spitsbergen); ground water influence on surface water chemistry: Journal of Hydrology, 529(Part 3), p. 1499-1510, illus. incl. 3 tables, sketch map, 39 ref., October 2015.

The article presents the investigation of surface water chemistry changes of the glacial Ebba River (Central Spitsbergen) during three melting seasons of 2008, 2009 and 2010. The twice daily water chemistry analyses allow recognition of the surface water chemistry differentiation. The surface water chemistry changes are related to the river discharge and changes in the influence of different water balance components during each melting season. One of the most important process that influence river water component concentration increase is groundwater inflow from active layer occurring on the valley area. The significance of this process is the most important at the end of the melting season when temperatures below 0 °C occur on glaciers (resulting in a slowdown of melting of ice and snow and a smaller recharge of the river by the water from the glaciers) while the flow of groundwater is still active, causing a relatively higher contribution of groundwater to the total river discharge. The findings presented in this paper show that groundwater contribution to the total polar river water balance is more important than previously thought and its recognition allow a better understanding of the hydrological processes occurring in a polar environment. Abstract Copyright (2015) Elsevier, B.V.

DOI: 10.1016/j.jhydrol.2015.08.031

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2016030841 Auken, Esben (Aarhus University, Institute for Geoscience, Aarhus, Denmark); Tulaczyk, Slawek M.; Foley, Neil; Dugan, Hilary; Schamper, Cyril; Peter, Doran; Virginia, Ross A. and Sorensen, Kurt. Exploring liquid water beneath glaciers and permafrost in Antarctica through airborne electromagnetic surveys [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract C13D-05, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Here, we demonstrate how high powered airborne electromagnetic resistivity is efficiently used to map 3D domains of unfrozen water below glaciers and permafrost in the cold regions of the Earth. Exploration in these parts of the world has typically been conducted using radar methods, either ground-based or from an airborne platform. Radar is an excellent method if the penetrated material has a low electrical conductivity, but in materials with higher conductivity, such as sediments with liquid water, the energy is attenuated . Such cases are efficiently explored with electromagnetic methods, which attenuate less quickly in conductive media and can therefore 'see through' conductors and return valuable information about their electrical properties. In 2011, we used a helicopter-borne, time-domain electromagnetic sensor to map resistivity in the subsurface across the McMurdo Dry Valleys (MDV). The MDV are a polar desert in coastal Antarctica where glaciers, permafrost, ice-covered lakes, and ephemeral summer streams coexist. In polar environments, this airborne electromagnetic system excels at finding subsurface liquid water, as water which remains liquid under cold conditions must be sufficiently saline, and therefore electrically conductive. In Taylor Valley, in the MDV, our data show extensive subsurface low resistivity layers beneath higher resistivity layers, which we interpret as cryoconcentrated hypersaline brines lying beneath glaciers and frozen permafrost. These brines appear to be contiguous with surface lakes, subglacial regions, and the Ross Sea, which could indicate a regional hydrogeologic system wherein solutes may be transported between surface reservoirs by ionic diffusion and subsurface flow. The system as of 2011 had a maximum exploration depth of about 300 m. However, newer and more powerful airborne systems can explore to a depth of 500-600 m and new ground based instruments will get to 1000 m. This is sufficient to penetrate to the base of almost all coastal Antarctic glaciers. The MDV, where conductive brines exist beneath resistive glacial ice and frozen permafrost, are especially well suited to exploration by airborne electromagnetic, but similarly suitable systems are likely to exist elsewhere in the cryosphere.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/79128

2016030561 O'Neal, Michael (University of Delaware, Department of Geological Sciences, Newark, DE); Meglioli, Andres and Schreiber, Erika. Modeling the distribution of mountain permafrost in the Central Andes, San Juan, Argentina [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 384, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.

A five-year field program in the high-altitude Dry Andes has focused on identifying and mapping the distribution of buried ice to better understand its potential contribution to the regional groundwater budget. The surface velocities of several rock glaciers and protalus ramparts, measured using repeat GPS, LIDAR, and Structure from Motion (SfM) data, range from 1 and 7 cm year-land suggest the presence of buried ice. However, many features that are frequently associated with permafrost conditions, such as sorted nets and solifluction lobes, are stationary, with no subsurface ice, and are likely relicts of past colder climates. Statistical analyses of temperature data from 69 sensors installed in the shallow subsurface across the latitudinal and altitudinal range of the study domain are used to predict permafrost conditions via mean annual ground temperature (MAGT) and bottom temperature of winter snow (BTS) based models. Our data and resultant models indicate that: 1) insolation and elevation are the essential variables for predicting ice locations, and 2) buried ice is discontinuous and only found at higher and topographically steeper portions of the landscape, when not in rock glaciers and protalus ramparts. When our surface motion and temperature data are compared with geophysical data and shallow (1 to 2 m) excavations in our study areas, we find that buried ice is typically associated with areas of thick debris cover in rock glaciers and protalus ramparts. Discontinuous ice does occur at elevations above 3800 m as our models predict, but the shallow depth to bedrock restricts its presence in these terrains. In contrast to other regional studies in the Dry Andes, we find that buried ice likely plays a limited role in the annual water budget at our two study sites, a result corroborated by previous geochemical and hydrological results at our locales. Our results underscore the importance of completing thorough field, surveying, and climate-modeling studies not only to separate active and relict landforms in an area where permafrost is protected by law as a periglacial feature, but also to allow for the development and coexistence of sustainable mining operations and local communities.

2016030807 Creighton, Andrea (University of Wyoming, Laramie, WY); Parsekian, Andrew; Arp, Christopher D.; Jones, Benjamin M.; Walter Anthony, Katey M. and Bondurant, Allen. Using surface NMR nuclear magnetic resonance to determine sediment structure and properties beneath thermokarst lakes [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract C11C-0787, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Thermokarst lakes form following the subsidence of ice-rich permafrost terrain and concurrent infilling of the depression with water. Areas of unfrozen sediment, called taliks, can form under lakes that have a mean annual bottom temperature greater than 0°C. Taliks are thought to play an important role in permafrost hydrology and carbon cycling. Sub-lake taliks can extend to depths of tens of meters, making them difficult and costly to measure by direct methods such as boreholes. Surface nuclear magnetic resonance (NMR) provides an unambiguous measurement of the liquid water content associated with unfrozen taliks; however, limitations of the measurements and the interpretation of the data still remain. Forward models were created to test the effect of varying water column thicknesses on the ability to resolve the depth and water content of taliks with parameters similar to geometries measured in late-winter field studies in the Arctic and Boreal regions of Alaska. The results of the forward modeling show that talik depth resolution decreases with a larger water column thickness, a shallower talik depth, and a lower water content. These results place constraints on our field measurements, with lakes greater than 9 m deep yielding potentially misleading inversion results. Field data was collected at a small, 4.6 m deep thermokarst lake near Fairbanks, Alaska, which had a known subsurface structure including talik depth, and available talik sediments from cores. Known subsurface structure was not used to inform the inversion model to determine how well talik depth could be resolved in lakes with unknown structure. With constraints placed on ice and water thickness, which are easily measured in the field, the blocky inversion model was able to accurately resolve the talik depth and water content for lakes less than 9 m deep.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/73601

2016030805 Fantello, Nadia (University of Wyoming, Laramie, WY); Parsekian, Andrew and Walter Anthony, Katey M. Estimating trapped gas concentrations as bubbles within lake ice using ground penetrating radar [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract C11C-0785, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Climate warming is currently one of the most important issues that we are facing. The degradation of permafrost beneath thermokarst lakes has been associated with enhanced methane emissions and it presents a positive feedback to climate warming. Thermokarst lakes release methane to the atmosphere mainly by ebullition (bubbling) but there are a large number of uncertainties regarding the magnitude and variability of these emissions. Here we present a methodology to estimate the amount of gas released from thermokarst lakes through ebullition using ground-penetrating radar (GPR). This geophysical technique is well suited for this type of problem because it is non-invasive, continuous, and requires less effort and time than the direct visual inspection. We are studying GPR data collected using 1.2 GHz frequency antennas in Brooklyn Lake, Laramie, WY, in order to quantify the uncertainties in the method. Although this is not a thermokarst lake, gas bubbles are trapped in the ice and spatial variability in bubble concentration within the ice is evident. To assess the variability in bulk physical properties of the ice due to bubbles, we gathered GPR data from different types of ice. We compared the velocity of the groundwave and reflection obtained from radargrams, and found on each case a larger value for the groundwave velocity suggesting a non-homogeneous medium and that the concentration of bubbles is prone to be near the surface instead of at greater depths. We use a multi-phase dielectric-mixing model to estimate the amount of gas present in a sample of volume of ice and found an uncertainty in relative permittivity (estimated using reflection velocity) of 0.0294, which translates to an uncertainty of 1.1% in gas content; and employing groundwave velocity we found 0.0712 and 2.9%, respectively. If locations of gas seeps in lakes could be detected and quantified using GPR along with field measurements, this could help to constrain future lake-source carbon gas estimates.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/63457

2016030806 Foley, Neil (University of California Santa Cruz, Earth and Planetary Sciences, Santa Cruz, CA); Tulaczyk, Slawek M.; Auken, Esben; Schamper, Cyril; Dugan, Hilary A.; Mikucki, Jill; Virginia, Ross A. and Doran, Peter T. Identification of subsurface brines in the McMurdo Dry Valleys, Antarctica, via an airborne EM resistivity survey [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract C11C-0786, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

We used a helicopter-borne time domain electromagnetic resistivity survey to detect and map hypersaline brines beneath glaciers and permafrost in the McMurdo Dry Valleys (MDV). In the MDV, a substantially ice-free region of coastal Antarctica, liquid water is present at the surface only in summer streams, ice-covered lakes with brackish to hypersaline bottom waters, and at Blood Falls, a hypersaline discharge from Taylor Glacier. Beneath the surface, however, water can remain liquid at temperatures below 0°C (and therefore at unexpectedly shallow depths) as a hypersaline brine. These brines, which are measured as zones of low resistivity in an otherwise high resistivity environment, are widespread in Taylor Valley, where they may connect lakes, subglacial waters, and the ocean. By using surface landscape characteristics--such as the presence of lakes, glaciers, or bare ground--we are able to compare changes in resistivity with depth. We find that in areas of surface permafrost (most of the MDV) there is a marked shift to low resistivity material around 200 m below the surface. At lakes, the stratified nature of their waters is detectable and sufficiently large lakes create taliks (unfrozen 'holes' in permafrost) that penetrate to the low resistivity zone around 200 m depth, suggesting connectivity through a regional aquifer. Underneath Taylor Glacier, we detect similar brines, which are the probable source for Blood Falls. These subglacial brines extend from the snout of Taylor Glacier (where they appear to connect to the hypersaline waters of West Lake Bonney) to the limit of our detection ability several kilometers up glacier where the ice became too thick for measurements. Our measurements are consistent with limited drilling done in the MDV during the 1970s and radar measurements taken more recently on Taylor Glacier. The transition to low resistivity at ~200 m depth occurs over a temperature range measured in boreholes of about -10 to -5°C, which is consistent with predictions of temperatures at the base of Taylor Glacier. The widespread nature of these brines may require reassessment of our understanding of Taylor Glacier's movement and the geochemistry of MDV lakes, which have historically been considered isolated from a regional aquifer.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/84801

2016030804 Hinkel, Kenneth M. (University of Cincinnati, Cincinnati, OH); Arp, Christopher D.; Eisner, Wendy R.; Frey, Karen E.; Grosse, Guido; Jones, Benjamin M.; Kim, Changjoo; Lenters, John D.; Liu, Hongxing and Townsend-Small, Amy. Final results from the Circumarctic Lakes Observation Network (CALON) project [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract C11C-0784, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Since 2012, the physical and biogeochemical properties of ~60 lakes in northern Alaska have been investigated under CALON, a project to document landscape-scale variability of Arctic lakes in permafrost terrain. The network has ten nodes along two latitudinal transects extending inland 200 km from the Arctic Ocean. A meteorological station is deployed at each node and six representative lakes instrumented and continuously monitored, with winter and summer visits for synoptic assessment of lake conditions. Over the 4-year period, winter and summer climatology varied to create a rich range of lake responses over a short period. For example, winter 2012-13 was very cold with a thin snowpack producing thick ice across the region. Subsequent years had relatively warm winters, yet regionally variable snow resulted in differing gradients of ice thickness. Ice-out timing was unusually late in 2014 and unusually early in 2015. Lakes are typically well-mixed and largely isothermal, with minor thermal stratification occurring in deeper lakes during calm, sunny periods in summer. Lake water temperature records and morphometric data were used to estimate the ground thermal condition beneath 28 lakes. Application of a thermal equilibrium steady-state model suggests a talik penetrating the permafrost under many larger lakes, but lake geochemical data do not indicate a significant contribution of subpermafrost groundwater. Biogeochemical data reveal distinct spatial and seasonal variability in chlorophyll biomass, chromophoric dissolved organic carbon (CDOM), and major cations/anions. Generally, waters sampled beneath ice in April had distinctly higher concentrations of inorganic solutes and methane compared with August. Chlorophyll concentrations and CDOM absorption were higher in April, suggesting significant biological/biogeochemical activity under lake ice. Lakes are a positive source of methane in summer, and some also emit nitrous oxide and carbon dioxide. As part of the Indigenous Knowledge component,76 Inupiat elders, hunters and berry pickers have been interviewed and over 75 hours of videotaped interviews produced. The video library and searchable interview logs are archived with the North Slope community. All field data is archived at ACADIS, and further information is at www.arcticlakes.org.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/58606

2016030808 Ulrich, Craig (Lawrence Berkeley National Laboratory, Berkeley, CA); Dafflon, Baptiste; Wu, Yuxin; Kneafsey, Timothy J.; López, Robin D.; Peterson, John and Hubbard, Susan S. Lab-scale investigation of multi-dimensional relationships between soil intrinsic properties to improve estimation of soil organic and ice content using novel core imaging and geophysical techniques in Arctic tundra [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract C11C-0788, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Shallow permafrost distribution and characteristics are important for predicting ecosystem feedbacks to a changing climate over decadal to century timescales. These can drive active layer deepening and land surface deformation, which in turn can significantly affect hydrological and biogeochemical responses, including greenhouse gas dynamics. Investigating permafrost soil intrinsic properties generally involves time-consuming and expensive lab-based analysis of few soil cores over a large area and extrapolating between points to characterize spatial variations in soil properties. Geophysical techniques provide lower resolution data over a spatially large area and when coupled with high-resolution point data can potentially estimate with greater accuracy the spatial variation of investigated properties, thus limiting the difficulty of collecting many soil cores in remote areas. As part of the Next-Generation Ecosystem Experiment (NGEE-Arctic), we investigate multi-dimensional relationships between various permafrost intrinsic soil properties, and further linkages with geophysical parameters such as density from X-ray computed tomography (CT) and electrical conductivity from electrical resistance tomography (ERT) to evaluate how best to constrain estimation of properties as soil organic carbon content, ice content and saturation across low- to high-centered polygon features in the arctic tundra. Results of this study enable the quantification of the multi-dimensional relationships between intrinsic properties, which can be further used to constrain estimation of such properties from geophysical data and/or where limited core-based information is available. This study also enables the identification of the key controls on soil electrical resistivity and density at the investigated permafrost site, including salinity, porosity, water content, ice content, soil organic matter, and lithological properties. Overall, inferred multi-dimensional relationships and related uncertainty enable probabilistic mapping of key parameters (organic content, ice content, etc.) using density and soil structural information from CT and bulk electrical resistivity.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/85107

2016030684 Byers, Logan C (University of Kansas, Department of Geology, Lawrence, KS); Stearns, Leigh A. and van der Veen, C. J. Polygonal surface patterns in the East Antarctic Plateau; morphology, genesis, stratigraphic implications, and relation to larger-scale surface structures [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 789, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.

The East Antarctic Ice Sheet (EAIS) is the largest reservoir of freshwater on Earth, and past changes in its volume have directly influenced global sea level since the Miocene. Contained within the ice sheet are atmospheric gases from the last million years, which provide an important data record for understanding the link between greenhouse gases and ice sheet evolution. Field excursions to the East Antarctic Plateau are few in count and limited in their spatial extent; therefore the surface of the EAIS remains an understudied locale. Despite this, a remarkable number of traverses observe and comment on surface cracks that are thin (1 cm to 60 cm wide), subvertical, non-planar, and bifurcating at depth. These cracks commonly intersect or connect to form irregular polygons with diameters of 5 m to 10 m in map view. The presence of these cracks is primarily isolated to areas where the surface slope is locally-increased in the prevailing wind direction and depositional rates of blowing snow are low. In these areas, a lack of insolation from snow cover promotes the development of a hard crust of oriented ice crystals by temperature-gradient driven vapor transport and solar-assisted recrystallization. The resemblance of the cracks to polygonally-patterned ground common in tundra and permafrost environments has sustained the long-standing hypothesis that the structures are formed by thermal contraction. To advance our understanding of the patterned ice, we apply both observational and numerical modeling techniques. Patterned ice is mapped and described using WorldView satellite images covering a few locations on the ice sheet. We present examples of polygon forms and make comparisons to known types of patterned ground. We numerically model thermally-induced stress in ice to test the thermal contraction origin of these cracks. We discuss the geographic proximity of patterned ice and ice sheet crevasses and develop hypotheses on the interrelation between the two. We discuss the form of these cracks in cross-section from published descriptions and reiterate that the structures assist in mixing modern atmosphere into the pores of relatively old ice, thereby blurring the resolution of paleoclimate records from deep Antarctic ice cores.

2016035363 Moine, Olivier (Centre National de la Recherche Scientifique, Laboratoire de Géographique Physique, Meudon, France). Weichselian upper pleniglacial environmental variability in north-western Europe reconstructed from terrestrial mollusc faunas and its relationship with the presence/absence of human settlements: in Environmental and cultural dynamics in Western and Central Europe during the upper Pleistocene (Brugal, Jean-Philip, editor; et al.), Quaternary International, 337, p. 90-113, illus. incl. sects., 1 table, sketch maps, 112 ref., July 9, 2014. Meeting: XVIII International Union for Quaternary Sciences congress, session on Environmental and cultural dynamics in Western and Central Europe during the upper Pleistocene, July 21-27, 2011, Bern, Switzerland.

During the Weichselian glaciation, millennial timescale climatic changes are a major cause of environmental variability, which influence the composition of large mammal fauna and the geographical distribution of human prehistoric populations. Nevertheless, precise environmental contexts of archaeological artefacts may remain unknown due to an unclear stratigraphy and/or to the bad preservation of paleoenvironmental proxies. As pollen is badly preserved in glacial loess deposits, a compilation of age constrained high resolution molluscan records is used to initiate the establishment of a canvas of millennial timescale spatial and temporal environmental changes in the European Loess Belt during the Weichselian Upper Pleniglacial (ca. 37-20 ka) to look for relationships with spatial distribution of human settlements. In this study, new terrestrial mollusc assemblages have been added to the database previously established for north-western Europe. They strengthen the position of the limit between the two molluscan-based biogeographical domains initially highlighted for north-western Europe: a flat and poorly vegetated western domain extending around the Channel and in Belgium, and a hilly domain with more diversified vegetation to the east. The analysis of molluscan data shows the persistence of these two domains throughout alternations of loess deposition phases (interstadial-stadial transitions and stadial phases) with phases of development and degradation of tundra gley horizon (stadial-interstadial transitions and interstadial phases). The interpretation of malacofauna from both domains combined with associated pedological and sedimentological features, climate modelling and comparisons with present tundra environments reveals a significant effect of both seasonality and snow cover along a longitudinal gradient between both domains, but also between phases of loess deposition and phases of tundra gley development. During interstadial phases, the intense functioning of the active layer and the degradation of permafrost in north-western Europe led to more homogeneous environments, which were less favourable for the diversity of both vegetation and terrestrial mollusc fauna. Presently, uncertainties of numerical ages still preclude precise correlations of loess units and tundra gley horizons between different sites and with nonlocal prehistoric occupations. However, a first raw comparison of the molluscan data with spatial distributions of Aurignacian, Gravettian and Solutrean-Upper Magdalenian lithic cultures reveals that the northern limit of the first two ones fits well with the south-eastern border of the poorly vegetated western domain also characterised by well-developed ice-wedge networks during phases of permafrost installation. Later, an important southward shift of human populations in western Europe resulted from the extreme aridity of the Last Glacial Maximum. Abstract Copyright (2014) Elsevier, B.V.

DOI: 10.1016/j.quaint.2014.02.030

2016034245 Debolskaya, Elena (Russian Academy of Sciences, Institute for Water Problems, Moscow, Russian Federation). A model of river bank deformations under the simultaneous effect of waves from a hydropower plant and warming: in Evolving water resources systems; understanding, predicting and managing water-society interactions (Castellarin, A., editor; et al.), Proceedings - International Association of Hydrological Sciences, 364, p. 32-37, illus. incl. sect., 8 ref., 2014. Meeting: Evolving water resources systems; understanding, predicting and managing water-society interactions, June 4-6, 2014, Bologna, Italy.

This paper presents a mathematical model of the river bed deformations in permafrost areas. The deformations are caused by the influence of waves of various origins under an increase of the ambient temperature. The model system consists of an unsteady hydrodynamic module, a thermal module and a bed deformation module. The hydrodynamic module is based on the two-dimensional shallow water equations. The bed deformation module is based on the sediment mass balance conditions. The thermal module is based on the Stefan equation, which defines the "water-ice" boundary movement. We present two applications of the model in which the bed deformation is calculated for the alluvial channels with melting bed under the influences of waves of different duration and intensity. We compared the model predictions with the laboratory data, generally obtaining a good agreement between the two.

URL: http://www.proc-iahs.net/364/32/2014/piahs-364-32-2014.pdf

2016030220 Herndon, Elizabeth (Kent State University, Department of Geology, Kent, OH); Chowdhury, Taniya Roy; Yang, Ziming; Graham, David; Gu, Baohua and Liang, Liyuan. Iron biogeochemistry in Arctic tundra soils [abstr.]: in Goldschmidt abstracts 2015, V.M. Goldschmidt Conference - Program and Abstracts, 25, p. 1248, 2015. Meeting: Goldschmidt 2015, Aug. 16-21, 2015, Prague, Czech Republic.

URL: http://goldschmidt.info/2015/uploads/abstracts/finalPDFs/1248.pdf

2016030685 Schmidt, Logan (University of Texas, Institute for Geophysics, Austin, TX) and Levy, Joseph. Hydraulic and thermal properties of McMurdo Dry Valleys soils; what Antarctic landscapes are at risk? [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 790, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.

Spatial variability in the hydraulic, physical, and thermal properties of active layer soils may reflect the fluvial and climatic history of cold-desert regions. In this study we measured the constant-head saturated hydraulic conductivity and grain-size-distribution of sixty-five soil samples taken from Taylor Valley, as well as the thermal diffusivity of twelve soil samples taken from met stations throughout the McMurdo Dry Valleys, Antarctica. Both the hydraulic conductivity and grain size distribution of soils are spatially organized within Taylor valley. Soils collected down-valley near McMurdo Sound have a higher percentage of fine-sized sediments (silt, clay) and lower hydraulic conductivities than soils collected up-valley near Taylor Glacier. Soils collected mid-valley have intermediate amounts of fines and conductivity values consistent with a hydrogeologic gradient spanning the valley. Soil hydraulic conductivity is strongly dependent on the presence of fines, with lower conductivities associated with soils containing a higher percentage of fines. The spatial organization of these soil properties within the valley suggests an active fluvial history in which glacier-fed channels, perhaps aided by water tracks, have flushed fine sediments down into lake basins. Three samples taken from neighboring Garwood Valley by contrast have very low conductivities, perhaps reflecting the less active fluvial history in that region that has left till un-eroded resulting in a soil column clogged with fines throughout the valley. Thermal diffusivity curves were created by measuring the thermal conductivity and heat capacity of soils collected from near Long Term Ecological Research project met stations. Soil thermal properties were measured over a range of water contents to provide a basis for interpreting the thermal history of Dry Valley soils and their stability under changing temperature and precipitation conditions. Three qualitative soil groups emerged from this analysis: soils with low diffusivities at all water contents, soils that slowly increase in diffusivity with increasing water content, and soils that exhibit high thermal diffusivity at low water contents. The first two groups are spatially correlated with ground ice, while the latter group is associated with thermokarst features.

2016034700 Bogucki, Andriy (Lwowski Uniwersytet Narodowy im. I. Franko, Lvov, Ukraine); Voloshyn, Petro and Tomeniuk, Olena. Zapadowosc plejstocenskich poziomow lessowo-glebowych i kriogenicznych Wolynia i Podola [The collapsibility of Pleistocene loess-palaeosols and cryogenic levels in Volhynia and Podolia]: in 5. Ogolnopolskie sympozjum "Wspolczesne problemy geologii inzynierskiej w Polsce" (Frankowski, Zbigniew, prefacer; et al.), Przeglad Geologiczny, 62(10/2), p. 553-559 (English sum.), 5 tables, 6 ref., 2014. Meeting: 5. Ogolnopolskie sympozjum "Wspolczesne problemy geologii inzynierskiej w Polsce", Oct. 15-17, 2014, Lublin, Poland.

The article presents the characteristics of collapse levels of stratigraphic loesses in Volhynia and Podolia. The authors examined the physical and mechanical properties of loess-palaeosols of the upper, middle and lower Pleistocene. Cryogenic processes and their effects on the collapsibility of loesses are discussed.

URL: http://www.pgi.gov.pl/docman-tree.html?task=doc_download&gid=2744

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2016030845 Urban, Frank E. (U. S. Geological Survey) and Clow, Gary D. DOI/GTN-P climate and active-layer data acquired in the National Petroleum Reserve-Alaska and the Arctic National Wildlife Refuge, 1998-2014: Data Series - U. S. Geological Survey, Rep. No. DS-0977, 2016.

DOI: 10.3133/ds977

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