Permafrost Monthly Alerts (PMAs)

2019092834 Luo Jing (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Laboratory of Frozen Soil Engineering, Lanzhou, China); Niu Fujun; Lin Zhanju; Liu Minghao and Yin Guoan. Recent acceleration of thaw slumping in permafrost terrain of Qinghai-Tibet Plateau; an example from the Beiluhe region: Geomorphology, 341, p. 79-85, illus. incl. 1 table, geol. sketch map, 55 ref., September 15, 2019.

Thaw slump activity has recently increased in permafrost areas of Qinghai-Tibet Plateau (QTP). Thaw slumps may influence the stability of infrastructure and impact global biogeochemical cycles. This study presents changes in retrogressive thaw slump in the Beiluhe Region based on interpretation of satellite imagery. Thaw slumping has become widespread in the region over the last ten years. The total number of thaw slumps has increased by 253% and the total affected area increased by 617%. The intensification of thaw slumping in the study region did not increase steadily over the study period, but was rather concentrated during two years: 2010 and 2016. This was mainly attributed to anomalously high air temperatures during the thawing season and abundant precipitation. Initiation of future thaw slumps on QTP will likely similarly be linked to changing trends in anomalous weather events and climate warming.

DOI: 10.1016/j.geomorph.2019.05.020

2019092854 Dai Licong (Chinese Academy of Science, Northwest Institute of Plateau Biology, Laboratory of Adaptation and Evolution of Plateau Botany, Xining, China); Guo Xiaowei; Du Yangong; Zhang Fawei; Ke Xun; Cao Yingfang; Li Yikang; Li Qian; Lin Li and Cao Guangmin. The response of shallow groundwater levels to soil freeze-thaw process on the Qinghai-Tibet Plateau: Ground Water, 57(4), p. 602-611, illus., 43 ref., July 2019.

The Qinghai-Tibet plateau has the world's largest area of seasonally frozen ground. Here, shallow groundwater displays behavior that is distinct from that elsewhere in the world. In the present study, we explore the seasonal and interannual variation of the shallow groundwater levels from 2012 to 2016, and attempt to quantitatively evaluate the relative influences of individual driving factors on the shallow groundwater levels based on boosted regression trees. The results show that: (1) on a seasonal scale, the groundwater levels were characterized by a double peak and double valley relationship, while on an interannual scale the groundwater levels showed a slightly downwards trend from 2012 to 2016; and (2) during the frozen period, the seasonal variation of groundwater levels was determined by mean air temperature through its effect on the soil thaw-freeze process, accounting for 53.15% of total variation. Meanwhile, ET₀ and rainfall exerted little impact on the seasonal variation of groundwater levels, which might be attributed to the aquitard of frozen soil that impedes the exchange between surface water and groundwater. Moreover, there was a lag between groundwater levels and soil freezing-thawing. During the non-frozen period, the mean air temperature was again the most important factor impacting the variation of groundwater levels, through its effect on ET₀, and accounted for 40.75% of total variation, while rainfall had little effect on groundwater levels when rainfall intensity was less than 12 mm/day. These results will benefit predictions of future trends in groundwater levels within the context of global warming. Abstract Copyright (2018), National Ground Water Association.

DOI: 10.1111/gwat.12832

2019097793 Ebel, Brian A. (U. S. Geological Survey, Water Cycle Branch, Lakewood, CO); Koch, Joshua C. and Walvoord, Michelle A. Soil physical, hydraulic, and thermal properties in interior Alaska, USA; implications for hydrologic response to thawing permafrost conditions: Water Resources Research, 55(5), p. 4427-4447, illus. incl. 6 tables, sketch map, 138 ref., May 2019.

Boreal forest regions are a focal point for investigations of coupled water and biogeochemical fluxes in response to wildfire disturbances, climate warming, and permafrost thaw. Soil hydraulic, physical, and thermal property measurements for mineral soils in permafrost regions are limited, despite substantial influences on cryohydrogeologic model results. This work expands mineral soil property quantification in cold regions through soil characterization from the discontinuous permafrost zone of interior Alaska, USA. Values extend beyond the range of prior measurement magnitudes in analogous regions, highlighting the importance of this data set. Rocky and silty upland soil landscape classifications and wildfire disturbance provided guiding frameworks for the sampling and analysis for potential implications for the hydrologic response to thawing permafrost. Bulk density (r_b), soil organic matter, soil-particle size distributions (sand, silt, and gravel fractions), and soil hydraulic properties of van Genuchten parameters alpha and N had moderate evidence of differences between silty and rocky classifications. Burned and unburned sites had only moderate evidence of differences for silt fraction. Field-saturated hydraulic conductivity (K_fs) was more variable at burned sites compared to unburned sites, which corresponded to observations of greater rooting depths at burned sites and observations of root paths in soil cores for K_fs measurement. Soil thermal properties suggested that gravel content may reduce the accuracy of commonly used estimation methods for thermal conductivity. This work provides soil parameter constraints necessary for hypothesis testing and site-specific prediction with cryohydrogeologic models to examine controls on active layer and permafrost dynamics in upland boreal forests. Abstract Copyright Published 2019. This article is a U.S. Government work and is in the public domain in the USA.

DOI: 10.1029/2018WR023673

2019100303 Lafrenière, Melissa J. (Queen's University, Department of Geography and Planning, Kingston, ON, Canada) and Lamoureux, Scott F. Effects of changing permafrost conditions on hydrological processes and fluvial fluxes: Earth-Science Reviews, 191, p. 212-223, illus. incl. block diag., 124 ref., April 2019.

This paper reviews the impacts of permafrost change on hydrological and related hydrochemical, particulate and organic fluxes in small Arctic catchments. While the emphasis is directed at High Arctic systems, literature and recent developments from other Arctic regions are also included. Hydrological change, particularly a shift from nival (snowmelt) dominance to increasing pluvial (rainfall) runoff contributions has important consequences for the timing and magnitude of hydrological fluxes. A key distinction is made between thermal perturbation, where changing melt season thaw conditions result in deep thaw with minimal geomorphic or surface hydrological effects, in contrast to physical perturbation, where permafrost change results in some form of thermokarst or physical disturbance such as mass movement or enhanced erosion. The latter disturbances are commonly expressed as localized thermo erosional gullies, active layer detachments and retrogressive thaw slumps. Results from recent research emphasise the importance of hydrological connectivity in terms of the downstream effect of a particular permafrost perturbation. Well-connected systems, either at the surface as channelized flows, or in the subsurface, through new or altered active layer flow pathways, result in substantial changes in downstream fluvial fluxes. Surface hydrological connectivity of localized permafrost disturbances increases transport of suspended sediment and particulate organic matter, the latter of which is often old and comparatively labile. Exposed ice in retrogressive thaw slumps sustains discharge during the melt season, further increasing fluxes. Thermal perturbation holds a substantially greater potential downstream impact due to widespread mobilization of solutes and dissolved organic carbon and nitrogen, and several studies point to rapid microbial alteration of carbon and inorganic nitrogen transformation in the shallow subsurface. Collectively, these results point to altered runoff, sediment transport and hydrochemical fluxes with spatial and hydrological controls.

DOI: 10.1016/j.earscirev.2019.02.018

2019100356 Selroos, Jan-Olof (Swedish Nuclear Fuel and Waste Management Company, Solna, Sweden); Cheng, Hua; Vidstrand, Patrik and Destouni, Georgia. Permafrost thaw with thermokarst wetland-lake and societal-health risks; dependence on local soil conditions under large-scale warming: Water (Basel), 11(3), Article no. 574, illus. incl. 1 table, 42 ref., March 2019.

A key question for the evolution of thermokarst wetlands and lakes in Arctic and sub-Arctic permafrost regions is how large-scale warming interacts with local landscape conditions in driving permafrost thaw and its spatial variability. To answer this question, which also relates to risks for ecology, society, and health, we perform systematic model simulations of various soil-permafrost cases combined with different surface-warming trends. Results show that both the prevalence and the thaw of permafrost depended strongly on local soil conditions and varied greatly with these for the same temperature conditions at the surface. Greater ice contents and depth extents, but also greater subsurface volumes thawing at depth under warming, are found for peat soils than other studied soil/rock formations. As such, more thaw-driven regime shifts in wetland/lake ecosystems, and associated releases of previously frozen carbon and pathogens, may be expected under the same surface warming for peatlands than other soil conditions. Such risks may also increase in fast permafrost thaw in mineral soils, with only small thaw-protection effects indicated in the present simulations for possible desertification enhancement of mineral soil covers.

DOI: 10.3390/w11030574

2019097569 Taylor, Liam S. (University of Leeds, School of Geography, Leeds, United Kingdom); Swindles, Graeme T.; Morris, Paul J.; Galka, Mariusz and Green, Sophie M. Evidence for ecosystem state shifts in Alaskan continuous permafrost peatlands in response to recent warming: Quaternary Science Reviews, 207, p. 134-144, illus. incl. 2 tables, sketch map, 72 ref., March 1, 2019.

Peatlands in continuous permafrost regions represent a globally-important store of organic carbon, the stability of which is thought to be at risk under future climatic warming. To better understand how these ecosystems may change in a warmer future, we use a palaeoenvironmental approach to reconstruct changes in two peatlands near Toolik Lake on Alaska's North Slope (TFS1 and TFS2). We present the first testate amoeba-based reconstructions from peatlands in continuous permafrost, which we use to infer changes in water-table depth and porewater electrical conductivity during the past two millennia. TFS1 likely initiated during a warm period between 0 and 300 CE. Throughout the late-Holocene, both peatlands were minerotrophic fens with low carbon accumulation rates (means of 18.4 and 14.2 g C m^-2 yr^-1 for cores TFS1 and TFS2 respectively). However, since the end of the Little Ice Age, both fens have undergone a rapid transition towards oligotrophic peatlands, with deeper water tables and increased carbon accumulation rates (means of 59.5 and 48.2 g C m^-2 yr^-1 for TFS1 and TFS2 respectively). We identify that recent warming has led to these two Alaskan rich fens to transition into poor fens, with greatly enhanced carbon accumulation rates. Our work demonstrates that some Arctic peatlands may become more productive with future regional warming, subsequently increasing their ability to sequester carbon.

DOI: 10.1016/j.quascirev.2019.02.001

2019100702 Sun Yat (Lanzhou University, College of Earth and Environmental Sciences, Laboratory of Western China's Environmental Systems, Lanzhou, China); Wang Yibo; Yang Wenjing; Sun Zhe and Zhao Jinpeng. Variation in soil hydrological properties on shady and sunny slopes in the permafrost region, Qinghai-Tibetan Plateau: Environmental Earth Sciences, 78(3), Article 100, illus. incl. 4 tables, sketch map, 69 ref., February 2019.

DOI: 10.1007/s12665-019-8067-9

2019101135 Euskirchen, E. S. (University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK); Kane, E. S.; Edgar, C. W. and Turetsky, M. R. When the source of flooding matters; divergent responses in carbon fluxes in an Alaskan rich fen to two types of inundation: Ecosystems (New York), Pre-Issue Publication, illus., 54 ref., 2019.

DOI: 10.1007/s10021-019-00460-z

2019101136 O'Donnell, Jonathan A. (U. S. National Park Service, Arctic Network, Anchorage, AK); Carey, Michael P.; Koch, Joshua C.; Xu, Xiaomei; Poulin, Brett A.; Walker, Jennifer and Zimmerman, Christian E. Permafrost hydrology drives the assimilation of old carbon by stream food webs in the Arctic: Ecosystems (New York), Pre-Issue Publication, illus. incl. sketch map, 76 ref., 2019.

DOI: 10.1007/s10021-019-00413-6

2019101152 Sheng Yu (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Lanzhou, China); Ma Shuai; Cao Wei and Wu Jichun. Spatiotemporal changes of permafrost in the headwater area of the Yellow River under a changing climate: Land Degradation & Development, Pre-Issue Publication, illus. incl. 1 table, sketch maps, 42 ref., 2019.

This article attempts to predict the spatiotemporal changes of permafrost in the Headwater Area of the Yellow River (HAYR) on the northeastern Qinghai-Tibet Plateau, Southwest China by using field monitoring and numerical models. Permafrost in the HAYR is categorized into four types: low- and high-ice-content high-plain permafrost and low- and high-ice-content alpine permafrost. According to these permafrost types, changes in permafrost temperature were calculated by coupling a geometric model with the soil thermal conduction model. Based on the calculation results, this paper evaluates the changes of permafrost in the HAYR over the past 50 years and predicts the change trends of permafrost in the HAYR under the scenarios of RCP2.6, RCP6.0, and RCP8.5 for possible climate change in 2050 and 2010 from the Intergovernmental Panel on Climate Change Fifth Assessment Report. The results show that (a) in the process of permafrost degradation, the same permafrost type at different degradation stages results in different modes and rates of increasing temperature. The response of permafrost to climate change differs in various degradation stages of permafrost; (b) from 1972 to 2012, the areal extent of permafrost degradation was 1,056 km2, resulting from a sharp air temperature increase after the 1980s. By 2050, the areal extent of permafrost degradation into seasonal frost is similar under the three scenarios of climate change. The areal extent of permafrost degradation is 2,224, 2,347, and 2,559 km2 or 7.5%, 7.9%, and 8.6% of the total area in the HAYR, respectively. In RCP2.6, the areal extent of permafrost degradation into seasonal frost by 2100 would be approximately 3,500 km2 greater than that by 2050. In RCP6.0, the areal extent of permafrost degradation by 2100 would be 10,000 km2 or 32.9% of the total area in the HAYR. In RCP8.5, the area of permafrost degradation by 2100 would be 18,492 km2 or 62.2% of the total area in the HAYR; (c) the active layer thickness (ALT) in the HAYR would increase significantly. The average of the ALT was 1.51 m by 1972 and 2.01 m by 2012, respectively. Under the RCP2.6, RCP6.0, and RCP8.5 scenarios, the basin?wide average of ALT would be 2.21, 2.40, and 3.08 m by 2050 and 2.78, 4.07, and 4.39 m by 2100, respectively.

DOI: 10.1002/ldr.3434

2019101151 Stanilovskaya, Julia (Sergeev Institute of Environmental Geoscience, Moscow, Russian Federation). Landslides in permafrost zone of Russia: in Landslides; theory, practice and modelling (Pradhan, Sarada Prasad, editor; et al.), Advances in Natural and Technological Hazards Research, 50, p. 303-313, 5 ref., 2019.

DOI: 10.1007/978-3-319-77377-3_14

2019096998 Creighton, Andrea L. (University of Wyoming, Department of Geology and Geophysics, Laramie, WY); Parsekian, Andrew D.; Angelopoulos, M.; Jones, Benjamin M.; Bondurant, A.; Engram, Melanie; Lenz, J.; Overduin, P. P.; Grosse, Guido; Babcock, E. and Arp, Christopher D. Transient electromagnetic surveys for the determination of talik depth and geometry beneath thermokarst lakes: Journal of Geophysical Research: Solid Earth, 123(11), p. 9310-9323, illus. incl. sects., 2 tables, sketch maps, 72 ref., November 2018. Geomagnetism and paleomagnetism/marine geology and geophysics.

Thermokarst lakes are prevalent in Arctic coastal lowland regions and sublake permafrost degradation and talik development contributes to greenhouse gas emissions by tapping the large permafrost carbon pool. Whereas lateral thermokarst lake expansion is readily apparent through remote sensing and shoreline measurements, sublake thawed sediment conditions and talik growth are difficult to measure. Here we combine transient electromagnetic surveys with thermal modeling, backed up by measured permafrost properties and radiocarbon ages, to reveal closed-talik geometry associated with a thermokarst lake in continuous permafrost. To improve access to talik geometry data, we conducted surveys along three transient electromagnetic transects perpendicular to lakeshores with different decadal-scale expansion rates of 0.16, 0.38, and 0.58 m/year. We modeled thermal development of the talik using boundary conditions based on field data from the lake, surrounding permafrost and a borehole, independent of the transient electromagnetics. A talik depth of 91 m was determined from analysis of the transient electromagnetic surveys. Using a lake initiation age of 1400 years before present and available subsurface properties the results from thermal modeling of the lake center arrived at a best estimate talk depth of 80 m, which is on the same order of magnitude as the results from the transient electromagnetic survey. Our approach has provided a noninvasive estimate of talik geometry suitable for comparable settings throughout circum-Arctic coastal lowland regions. Abstract Copyright (2018). American Geophysical Union. All Rights Reserved.

DOI: 10.1029/2018JB016121

2019092769 Oldenborger, Greg A. (Natural Resources Canada, Geological Survey of Canada, Ottawa, ON, Canada) and LeBlanc, Anne-Marie. Monitoring changes in unfrozen water content with electrical resistivity surveys in cold continuous permafrost: Geophysical Journal International, 215(2), p. 965-977, illus. incl. sects., sketch map, 65 ref., November 2018. Includes appendix.

For permafrost, information on unfrozen water content is critical for thermal modelling, understanding permafrost evolution and for predicting thaw susceptibility for infrastructure. We utilize electrical resistivity surveys for the detection and monitoring of unfrozen water content in cold continuous permafrost. We develop a data processing scheme based on a common subset of reciprocal measurements to filter data from irregular acquisitions in variable environmental conditions to a standard noise level, such that models recovered from disparate data sets can be compared quantitatively. Using temperature-corrected post-inversion model differencing, changes in recovered electrical resistivity models are used to calculate the relative change in unfrozen water content over common regions of high model resolution. The technique is applied to electrical resistivity data collected seasonally using a permanent electrode installation in cold continuous permafrost alongside airport infrastructure in the Canadian Arctic. The number of healthy data decreases over the experiment duration, with a correlation between data quality and ground surface temperature. Using the resistivity models, relative changes in unfrozen water content are estimated that are consistent with temperature records. Results are compared to an empirical temperature-dependent water content model obtained via calibrated thermal modelling at the study site. When compared to the empirical model, the changes in resistivity overpredict the changes in unfrozen water content due to temperature-induced phase changes alone after one year of acquisition. Prevalent changes in unfrozen water content occur in a zone below the active layer at temperatures of approximately 0 to -4.5°C, and may be indicative of permafrost evolution involving ice formation or water movement over many months in moderately-saline permafrost beneath airport infrastructure.

DOI: 10.1093/gji/ggy321

2019094574 Chang Juan (Lanzhou University, College of Earth and Environmental Systems, Key Laboratory of Western China's Environmental Systems, Lanzhou, China); Ye Renzheng and Wang Genxu. Progress in permafrost hydrogeology in China: in Groundwater sustainability in fast-developing China (Wang Yanxin, editor; et al.), Hydrogeology Journal, 26(5), p. 1387-1399 (French, Spanish, Chinese, Portuguese sum.), illus. incl. 2 tables, sketch map, 90 ref., August 2018.

DOI: 10.1007/s10040-018-1802-6

2019096761 Li Haipeng (China University of Mining and Technology, State Key Laboratory for Geomechanics and Deep Underground Engineering, Xuzhou, China); Yang, Zhaohui (Joey) and Wang Jiahui. Unfrozen water content of permafrost during thawing by the capacitance technique: Cold Regions Science and Technology, 152, p. 15-22, illus. incl. 5 tables, August 2018. Based on Publisher-supplied data.

The capacitance method is portable, safe in terms of no radiation hazard, fast in terms of response time, and cheap, and has been widely used to measure the water content of unfrozen soils. However, it is sensitive to installation, salinity, temperature, bulk density, and clay content. Calibration for specific soil types of interest is essential for improved accuracy. This paper explores using the capacitance technique to measure the unfrozen water content of permafrost. It presents a detailed capacitance sensor calibration process, data, and regression equations for describing the relationship between volumetric water content and the sensor output. The subfreezing temperature effects on the sensor electronics response and on the relative permittivity or dielectric constant of water, ice, and oven-dry soil minerals are investigated. The obtained unfrozen water content results are used for estimating the heat capacity of permafrost, which is compared with that measured by using the Transient Line Heat Source method at thawed status. It is found that the temperature effects on the relative permittivity of ice and soil minerals are small and can be ignored. However, the temperature effect on the sensor electronics response is almost linear, that on the relative permittivity of water is significant and should be accounted for. The unfrozen water content for permafrost of silty sand, silt and clay nature was assessed for temperatures ranging from -20°C to 10°C, and found to be consistent with previous findings; empirical relationships between the unfrozen water content and temperature were obtained. In addition, the heat capacity of permafrost samples was estimated based on the weighted average method and the unfrozen water content, and a good agreement was found between the estimated and measured heat capacity values for all samples at thawed status.

DOI: 10.1016/j.coldregions.2018.04.012

2019098022 Alekseev, Ivan (Saint Petersburg State University, Department of Applied Ecology, St. Petersburg, Russian Federation); Shamilishvilly, George and Abakumov, Evgeny. Content of trace elements in selected permafrost-affected soils of Yamal region with different functional load: Polarforschung, 88(2), p. 125-133 (German sum.), illus. incl. 6 tables, sketch map, 30 ref., 2018.

Soils are an important component of polar ecosystems and play a key role in their functioning. They have a significant role in processes of accumulation, mobilization, redistribution of chemical, and especially, trace elements in landscapes and ecosystems. Both anthropogenic factors and climate change may affect biogeochemistry of soils in permafrost-affected landscapes, which are considered as highly sensitive to climate change and anthropogenic forcing. Involvement of additional portions of trace elements into the soils due to permafrost degradation and thawing is considered as one the main risk factors for natural environments in polar regions. Therefore, trace elements contents in soils of urban areas (Kharsaim, Aksarka, Salekhard, Harp and Labytnangi) and natural environments of the Yamal region (Ust'Uribey and Beliy island) were investigated. Soil samples from Kharp settlement show the highest content for Cu, Pb, Zn, Ni, connected with existing galvanizing plant "Kongor-chrome". The highest values for Pb occur in soil samples from Aksarka and Labytnangi key plots. Soil samples from Kharsaim and Kharp key plots are characterized by the highest median values for Zn. Analysis of trace elements content show poorly manifested eluvial-illuvial differentiation of soil profiles of natural soils. The highest content for most of the studied trace elements has been revealed in topsoil horizons. Trace elements content in soil samples collected from urban environments ranged significantly high due to differences in the functional zones of the sites and a predominant anthropogenic source of trace elements additions. The results of statistical analysis show that statistically significant differences in Ni and Cu content in soils appear only between Kharp settlement and each of natural sites Ust'-Uribey and Beliy Island. Almost all studied urban soils reveal significant differences in Pb, Zn, As, and Fe contents between natural sites.

DOI: 10.2312/polarforschung.88.2.125

2019100326 Baughman, Carson A. (U. S. Geological Survey, Alaska Science Center, Anchorage, AK); Jones, Benjamin M.; Bodony, Karin L.; Mann, Daniel H.; Larsen, Chris F.; Himelstoss, Emily and Smith, Jeremy. Remotely sensing the morphometrics and dynamics of a cold region dune field using historical aerial photography and airborne LiDAR data: Remote Sensing, 10(5), 19 p., illus. incl. 3 tables, geol. sketch maps, 73 ref., 2018.

This study uses an airborne Light Detection and Ranging (LiDAR) survey, historical aerial photography and historical climate data to describe the character and dynamics of the Nogahabara Sand Dunes, a sub-Arctic dune field in interior Alaska's discontinuous permafrost zone. The Nogahabara Sand Dunes consist of a 43-km² area of active transverse and barchanoid dunes within a 3200-km² area of vegetated dune and sand sheet deposits. The average dune height in the active portion of the dune field is 5.8 m, with a maximum dune height of 28 m. Dune spacing is variable with average crest-to-crest distances for select transects ranging from 66-132 m. Between 1952 and 2015, dunes migrated at an average rate of 0.52 m a^-1. Dune movement was greatest between 1952 and 1978 (0.68 m a^-1) and least between 1978 and 2015 (0.43 m a^-1). Dunes migrated predominantly to the southeast; however, along the dune field margin, net migration was towards the edge of the dune field regardless of heading. Better constraining the processes controlling dune field dynamics at the Nogahabara dunes would provide information that can be used to model possible reactivation of more northerly dune fields and sand sheets in response to climate change, shifting fire regimes and permafrost thaw.

DOI: 10.3390/rs10050792

2019100335 Kizyakov, Alexander (Lomonosov Moscow State University, Cryolithology and Glaciology Department, Moscow, Russian Federation); Khomutov, Artem; Zimin, Mikhail; Khairullin, Rustam; Babkina, Elena; Dvornikov, Yury and Leibman, Marina. Microrelief associated with gas emission craters; remote-sensing and field-based study: Remote Sensing, 10(5), 21 p., illus. incl. 4 tables, sketch maps, 23 ref., 2018.

Formation of gas emission craters (GEC) is a new process in the permafrost zone, leading to considerable terrain changes. Yet their role in changing the relief is local, incomparable in the volume of the removed deposits to other destructive cryogenic processes. However, the relief-forming role of GECs is not limited to the appearance of the crater itself, but also results in positive and negative microforms as well. Negative microforms are rounded hollows, surrounded by piles of ejected or extruded deposits. Hypotheses related to the origin of these forms are put forward and supported by an analysis of multi-temporal satellite images, field observations and photographs of GECs. Remote sensing data specifically was used for interpretation of landform origin, measuring distances and density of material scattering, identifying scattered material through analysis of repeated imagery. Remote-sensing and field data reliably substantiate an impact nature of the hollows around GECs. It is found that scattering of frozen blocks at a distance of up to 293 m from a GEC is capable of creating an impact hollow. These data indicate the influence of GEC on the relief through the formation of a microrelief within a radius of 15-20 times the radius of the crater itself. Our study aims at the prediction of risk zones.

DOI: 10.3390/rs10050677

2019099989 Melnikov, Vladimir (Tyumen State University, Institute of Cryology, Tyumen, Russian Federation); Gennadinik, Viktor; Kulmala, Markku; Lappalainen, Hanna K.; Petaja, Tuukka and Zilitinkevich, Sergej. Cryosphere; a kingdom of anomalies and diversity: Atmospheric Chemistry and Physics, 18(9), p. 6535-6542, illus., 42 ref., 2018.

The cryosphere of the Earth overlaps with the atmosphere, hydrosphere and lithosphere over vast areas with temperatures below 0 °C and pronounced H₂O phase changes. In spite of its strong variability in space and time, the cryosphere plays the role of a global thermostat, keeping the thermal regime on the Earth within rather narrow limits, affording continuation of the conditions needed for the maintenance of life. Objects and processes related to cryosphere are very diverse, due to the following basic reasons: the anomalous thermodynamic and electromagnetic properties of H₂O, the intermediate intensity of hydrogen bonds and the wide spread of cryogenic systems all over the Earth. However, these features attract insufficient attention from research communities. Cryology is usually understood as a descriptive discipline within physical geography, limited to glaciology and permafrost research. We emphasise its broad interdisciplinary landscape involving physical, chemical and biological phenomena related to the H₂O phase transitions and various forms of ice. This paper aims to draw the attention of readers to the crucial importance of cryogenic anomalies, which make the Earth atmosphere and the entire Earth system very special, if not unique, objects in the universe.

DOI: 10.5194/acp-18-6535-2018

2019099990 Salzano, Roberto (National Research Council of Italy, Institute of Atmospheric Pollution Research, Florence, Italy); Pasini, Antonello; Ianniello, Antonietta; Mazzola, Mauro; Traversi, Rita and Udisti, Roberto. High time-resolved radon progeny measurements in the Arctic region (Svalbard islands, Norway); results and potentialities: Atmospheric Chemistry and Physics, 18(9), p. 6959-6969, illus., 41 ref., 2018.

The estimation of radon progeny in the Arctic region represents a scientific challenge due to the required low limit of detection in consideration of the limited radon emanation associated with permafrost dynamics. This preliminary study highlighted, for the first time above 70° N, the possibility to monitor radon progeny in the Arctic region with a higher time resolution. The composition of the radon progeny offered the opportunity to identify air masses dominated by long-range transport, in presence or absence of near-constant radon progeny instead of long- and short-lived progenies. Furthermore, the different ratio between radon and thoron progenies evidenced the contributions of local emissions and atmospheric stability. Two different emanation periods were defined in accordance with the permafrost dynamics at the ground and several accumulation windows were recognized coherently to the meteo-climatic conditions occurring at the study site.

DOI: 10.5194/acp-18-6959-2018

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2019101039 King, Tyler V. (Utah State University, Utah Water Research Laboratory, Logan, UT) and Neilson, Bethany T. Characterization of thermal anomalies in a tundra river using thermal infrared imagery [abstr.]: in Geological Society of America, 2019 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 51(5), Abstract no. 53-2, September 2019. Meeting: Geological Society of America, 2019 annual meeting & exposition, Sept. 22-25, 2019, Phoenix, AZ.

Spatial heterogeneity in river temperatures provide important thermal refuge habitat for cold-water aquatic taxa in many temperate and tropical rivers. As climate change progresses in the Arctic, it is feasible that the endemic fish populations will seek out similar refuges from increasing river temperatures during dry periods throughout summer months. However, little is known about the occurrence, distribution, and drivers of thermal heterogeneity of Arctic Rivers. In this study we present an analysis of thermal anomalies for a 35 km long reach of the Kuparuk River, Alaska. Using high-resolution thermal Infrared (TIR) imagery from repeat aerial surveys we identified the spatial distribution and magnitude of thermal anomalies under a wide range of flow conditions. We classified these thermal anomalies based on associated hydraulic/hydrologic features to develop a conceptual model of the processes that produce thermal heterogeneity in Arctic rivers, and how these processes vary with hydrologic condition. Our preliminary results show that 1) nearly all thermal anomalies were colder than mean river temperatures, 2) thermal anomalies were found to be associated with four major hydraulic/hydrologic features: tributary and water track mouths, surface transient storage zones, and the downstream side of gravel bars, 3) there were limited differences in the magnitude of thermal anomalies across hydraulic/hydrologic features, 4) the abundance and severity of thermal anomalies were inversely related to river discharge, and 5) the abundance of thermal anomalies in response to changes in discharge varied most for gravel bars and least for tributaries. These findings show that thermal anomalies are abundant under current hydrometeorologic conditions, and highlight the influence of permafrost, landscape connectivity, and groundwater/surface water interactions on producing spatial thermal heterogeneity. Further research is required to determine the sensitivity of currently observed thermal anomalies to projected changes in basin characteristics, such as increased depth of permafrost thaw and alterations to hydrologic regimes, and to determine the efficacy of these thermal anomalies as thermal refugia.

2019098157 Landing, Ed (New York State Museum, Albany, NY); Lipps, Jere H. and Geyer, Gerd. Limits of atmospheric pCO₂ in reconstructing ancient and predicting future climate; the roles of global reflectance and continent distribution [abstr.]: in Geological Society of America, 2019 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 51(5), Abstract no. 36-26, September 2019. Meeting: Geological Society of America, 2019 annual meeting & exposition, Sept. 22-25, 2019, Phoenix, AZ.

The dominant models for ancient and future global temperatures draw on Svante Arrhenius' 1896 insights. He concluded CO₂ was a key temperature driver and anticipated the modern climate catastrophe by calculating the effect of rising industrial CO₂ emissions. The link from the late-19th century of rising temperature with ever higher pCO₂ based on atmospheric and ice core samples substantiates his conclusions and illustrates warming by the greenhouse model. Greenhouse warming will accelerate with increasing pCO₂ (ca. 2.5 ppm/yr, 340-405 ppm over 1980-2019) and feed-backs that increase greenhouse gas concentration (e.g., permafrost melting with CO₂ and methane release, slowed CO₂ storage by the biotic effects of oceanic acidification and drying-out of temperate forests, lower CO₂ uptake by warming oceans). Arrhenius showed the marginal radiative forcing of CO₂ was highest at 200 ppm, fell at higher pressures, with the "warming effect" effectively capped at 1,000 ppm--a value likely reached in less than 200 years with feedbacks and humanity's uncertain response. But, the warming rate will increase as non-greenhouse factors will come to dominate Earth's temperature by lowering of its albedo (reflectivity). Thus, melting of ca. 50% of reflective Arctic Ocean pack ice over 30 yr has increased global warming rate by ca. 25%--a rate that will accelerate with complete global ice loss. Ice melt accelerates the eustatic rise rate by 3.1 mm/yr. over each previous year, with heat absorbing and higher insolation water ultimately covering ca. 15% of the more reflective land. An adequate global temperature model must incorporate 1) analysis that shows Phanerozoic temperatures independent/slightly negatively correlated with the very high pCO₂ values of the GEOCARB model (levels sometimes incompatible with terrestrial metazoans and many embryophytes), 2) the rapid pCO₂ fall in the Devonian with no significant temperature decrease, and 3) the lower "warming effect" above 1,000 ppm. Global temperature models must include non-greenhouse (i.e., hyperwarming) factors as changed albedo with eustatic rise/fall and ice loss/growth, lower vs higher latitude continent distributions, and presence of a polar continent/restricted polar ocean.

2019100815 Muskett, Reginald Reed (University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK). To measure the changing relief of Arctic rivers; a Synthetic Aperture Radar experiment in Alaska [abstr.]: in Geological Society of America, 2019 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 51(5), Abstract no. 17-8, September 2019. Meeting: Geological Society of America, 2019 annual meeting & exposition, Sept. 22-25, 2019, Phoenix, AZ.

The rivers crossing the lowland tundra-permafrost of the continuous permafrost zone of the Alaska North Slope can have extensive floodplain relief not simply created by channel migration during spring floods alone. Many of the rivers have channel-beds inherited from glacial landscapes and Holocene to present-day para-glacial and periglacial processes and mountain gradient sources. Interest is turning to understand effects from permafrost and ice wedge networks (ground ice) thaw, degradation and erosion and how such effects impact carbon and water equivalent mass balance. The 2015 flooding of the Sagavanirktok River crossing the Alaska North Slope brings this and additional impacts to-and-by human infrastructure into focus. Geodetic methods to measure centimeter to millimeter-scale changes using aircraft and satellite-deployed Synthetic Aperture Radio Detection And Ranging cannot ignore volume scattering. Backscatter and coherence at L-frequency and others possess both surface and volumetric scattering. On lowland tundra underlain by permafrost volume scattering dominants the RADAR backscatter coherence. Measurement of the L-frequency penetration depth for evaluation of mass change (carbon and water equivalent loss and transport) through permafrost and ground ice thaw-degradation with erosion is necessary. The Jet Propulsion Laboratory-National Aeronautical and Space Administration airborne Uninhabited Aerial Vehicle SAR (UAVSAR) L-frequency full quad-polarimetry cross-pole HHVV (polarization rotation, Horizontal to Vertical) confirms the dominance of volume scattering on lowland tundra (RADAR-soft targets) whereas surface scattering (HHHH or VVVV, no rotation) dominates on river channel deposits, rock outcrops and metal objects (RADAR-hard targets). Quantifying polarization rotation and the L-frequency penetration depth on lowland tundra are challenges for a new field validation and verification experiment: To Measure The Changing Relief of Arctic Rivers.

2019098150 Wadhams, Jane A. (Florida State University, Department of Earth, Ocean and Atmospheric Sciences, Tallahassee, FL); Owens, Jeremy D.; Newby, Sean M. and Them, Theodore R., II. Evidence for increased ocean oxygenation during the recovery of the Paleocene-Eocene Thermal Maximum [abstr.]: in Geological Society of America, 2019 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 51(5), Abstract no. 36-19, September 2019. Meeting: Geological Society of America, 2019 annual meeting & exposition, Sept. 22-25, 2019, Phoenix, AZ.

The rate and magnitude of the release of carbon that characterizes the Paleocene-Eocene Thermal Maximum (PETM; ~55.9 Ma) and the most recent climate perturbation make it the best analogue to study to better constrain modern climate scenarios. The mechanism(s) triggering the PETM remain debated but include a bolide impact and/or release of greenhouse gases via volcanoes, wildfires, or other marine and terrestrial carbon reservoirs, which all produce isotopically light sources of carbon. The sharp ~3 ppm negative carbon isotope excursion defines the PETM and suggests a major perturbation to the global carbon cycle through the release of isotopically light carbon to the ocean-atmosphere system. In addition to warming, other environmental perturbations during this event include ocean acidification, permafrost loss, and a small increase in global euxinia (anoxic and sulfidic water column). There is limited evidence, however, for widespread deoxygenation or organic carbon burial, which contrasts the PETM with Mesozoic oceanic anoxic events. This research aims to better constrain the global spatiotemporal redox structure across the PETM global oceans using both novel and traditional geochemical tools. We analyzed samples from IODP Expedition 302, Site M0004-A using a suite of novel geochemical proxies such as trace metal concentrations, iron speciation, and thallium isotopes to constrain the local and global redox conditions before, during, and after the PETM. Thallium isotopes--a novel proxy that responds to the global burial of manganese oxides across short-term redox events and thus tracks earliest changes in marine oxygenation - suggest that reducing conditions prevailed before and during the carbon isotope excursion, followed by more oxic conditions during the recovery of the event, or that the basin was restricted before the event and became more connected to the oxic open ocean. Potential restriction may impact conclusions of previous geochemical work on the same samples. If this is a global signal, then it suggests the ocean can rapidly reoxygenate in the wake of a climate perturbation, which has important implications for modern deoxygenation. To corroborate these data, additional sections will be analyzed to constrain the global vs. local signatures for thallium isotopes and other geochemical data.

2019100419 Ceperley, Elizabeth G. (University of Wisconsin at Madison, Department of Geoscience, Madison, WI); Marcott, Shaun A.; Rawling, J. Elmo, III; Zoet, Lucas K. and Zimmerman, Susan H. The role of permafrost on the morphology of an MIS 3 moraine from the southern Laurentide ice sheet [abstr.]: in Geological Society of America, South-Central Section, 53rd annual meeting; Geological Society of America, North-Central Section, 53rd annual meeting; Geological Society of America, Rocky Mountain Section, 71st annual meeting, Abstracts with Programs - Geological Society of America, 51(2), Abstract no. 11-4, March 2019. Meeting: Geological Society of America, South-Central Section, 53rd annual meeting; Geological Society of America, North-Central Section, 53rd annual meeting; Geological Society of America, Rocky Mountain Section, 71st annual meeting, March 25-27, 2019, Manhattan, KS.

The Laurentide Ice Sheet (LIS) represents the single largest contributor to global sea level during the late Pleistocene glacial-interglacial cycles. Fluctuations of global sea level prior to the Last Glacial Maximum (LGM; 26-19 ka) are well documented, but the terrestrial extent of the LIS prior to the LGM is uncertain. In central Wisconsin, three closely spaced end moraines of the LIS are preserved. The two innermost moraines are constrained to LGM-age through isotopic dating, yet the outermost moraine is estimated to be up to >125 ka based on relative dating techniques. Here we report surface exposure ages from this outermost moraine (the Arnott Moraine) and demonstrate that the LIS reached its most extensive position in central Wisconsin during Marine Isotope Stage (MIS) 3 at approximately 37 ka. These new age constraints for the Arnott Moraine are significantly younger than prior estimates, which were based on sediment weathering and a highly diffused moraine morphology. To address this dichotomy between the relatively young exposure dates and highly diffuse geomorphology, we apply a landscape diffusion model to the Arnott Moraine and find that during permafrost conditions intense weathering can act to efficiently and quickly smooth the older moraine surface. This study implicates the LIS as a potential source for the 10-30 m drop in sea level during MIS 3 while simultaneously demonstrating the inherent uncertainty associated with relative dating techniques if nonlinear weathering conditions are not accounted for in periglacial terrains.

2019097820 Duvillard, Pierre-Allain (Université Savoie Mont-Blanc, Laboratoire Environnements, Dynamiques et Territoires de la Montagne, Chambery, France); Ravanel, Ludovic; Schoeneich, Philippe; Marcer, Marco and Piard, Jean-François. Analyse multi-méthodes de la déstabilisation d'un pylône de remontee mécanique implanté sur un glacier rocheux des Alpes françaises [Multi-method analysis of the destabilization of a mechanical lift tower located on a rock glacier in the French Alps]: in Actes des 19èmes journées des jeunes géomorphologues (Fressard, Mathieu, editor; et al.), Géomorphologie: Relief, Processus, Environnement, 25(1), p. 21-36 (English sum.), illus. incl. sects., strat. cols., 2 tables, geol. sketch maps, 63 ref., 2019. Meeting: 19èmes journées des jeunes géomorphologues, Jan. 26-27, 2018, Lyons, France. Includes appendix.

In the Val Thorens ski resort (Savoie, France), more than 79 infrastructure elements related to ropeway transport systems are located on permafrost. During the last decade, three of them (two top stations and a pylon located around 3,000 m a.s.l.) experienced destabilization which required important adjustment and stabilization work. This study investigates the destabilization of the pylon #2 of the Thorens funitel that occurred during the Summer 2016. Its foundations were affected by horizontal displacement and subsidence, causing a metric shift of the pylon top with respect to the cable. The pylon was built on a rock glacier which morphology was severely altered by earth work aiming to develop a ski slope. A multidisciplinary analysis was conducted in order to understand the processes that led to the pylon destabilization with a focus on the role of the morphological alterations of anthropogenic origin on the rock glacier dynamic. We used (i) a stratigraphic data analysis from boreholes and (ii) a subsurface analysis based on geophysics (Electrical Resistivity Tomography profiles) to understand the rock glacier internal structure, while (iii) geomorphological surface modifications were investigated by comparing digital terrain models obtained by aerial photogrammetry before and after the earthwork. This study highlights the preparatory role of the earthwork and a non-control of the surface water flow in an ice-rich environment such as a rock glacier.

DOI: 10.4000/geomorphologie.12945

2019094647 Bao, Y. F. (State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Beijing, China); Wang, Y. C. and Hu, M. M. The CO₂ system and implications in the Yarlung Tsangpo River on the Tibetan Plateau [abstr.]: in Goldschmidt abstracts 2018, V.M. Goldschmidt Conference - Program and Abstracts, 28, 2018. Meeting: Goldschmidt 2018, Aug. 12-17, 2018, Boston, MA.

URL: https://goldschmidtabstracts.info/2018/130.pdf

2019097061 Jubb, Aaron M. (Oak Ridge National Laboratory, Oak Ridge, TN); Eskelsen, Jeremy R.; Yin, Xiangping; Zheng, Jianqiu; Philben, Michael J.; Pierce, Eric M.; Graham, David E.; Wullschleger, S. D. and Gu, Baohua. Characterization of iron oxide biofilms from Arctic tundra air-water interfaces [abstr.]: in Goldschmidt abstracts 2018, V.M. Goldschmidt Conference - Program and Abstracts, 28, 2018. Meeting: Goldschmidt 2018, Aug. 12-17, 2018, Boston, MA.

URL: https://goldschmidtabstracts.info/abstracts/abstractView?id=2018003045

2019094690 Patzner, Monique-Sezanne (University of Tübingen, Center for Applied Geoscience, Tubingen, Germany); Malusova, Miroslava; Nikeleit, Verena; Kappler, Andreas and Bryce, Casey. Microbial iron cycling during permafrost thaw [abstr.]: in Goldschmidt abstracts 2018, V.M. Goldschmidt Conference - Program and Abstracts, 28, 2018. Meeting: Goldschmidt 2018, Aug. 12-17, 2018, Boston, MA.

URL: https://goldschmidtabstracts.info/2018/1966.pdf

2019094719 Peak, Derek (University of Saskatchewan, Department of Soil Science, Saskatoon, SK, Canada); Siciliano, Steven D.; Chang, Yu-Fen; Conway, Alix; Shannon, Whitney; Mamet, Steven; Helgason, Bobbi; Talebitaher, Alireza; Papandreou, Zisis; Palaia, Tom; Teymurazyan, Aram and Regier, Tom. Microbes and minerals in permafrost; quantifying microbe mineral interactions using positron emission tomography coupled to soft X-ray spectroscopy of psychotrophic bioremediation in permafrost soils [abstr.]: in Goldschmidt abstracts 2018, V.M. Goldschmidt Conference - Program and Abstracts, 28, p. 94, 2018. Meeting: Goldschmidt 2018, Aug. 12-17, 2018, Boston, MA.

URL: https://goldschmidtabstracts.info/2018/1975.pdf

2019094710 Trusiak, Adrianna (University of Michigan, Earth and Environmental Science, Ann Arbor, MI); Treibergs, Lija A.; Kling, George W.; Noël, Vincent; Bargar, John R. and Cory, Rose M. The role of iron complexation in the production of reactive oxygen species and CO₂ in arctic soil waters [abstr.]: in Goldschmidt abstracts 2018, V.M. Goldschmidt Conference - Program and Abstracts, 28, 2018. Meeting: Goldschmidt 2018, Aug. 12-17, 2018, Boston, MA.

URL: https://goldschmidtabstracts.info/2018/2572.pdf

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