Permafrost Monthly Alerts (PMAs)

2016076481 Pokrovsky, Oleg S. (Géosciences Environnement Toulouse, Toulouse, France); Manasypov, Rinat M.; Loiko, Sergey V. and Shirokova, Liudmila S. Organic and organo-mineral colloids in discontinuous permafrost zone: Geochimica et Cosmochimica Acta, 188, p. 1-20, illus. incl. 2 tables, sketch map, 127 ref., September 2016. Includes appendices.

On-going permafrost thaw in discontinuous permafrost regions produces significant amounts of small permafrost subsidence and depressions, while large lakes are likely to drain into streams and rivers. The intensification of permafrost thaw may alter the size distribution and chemical composition of organo-Fe-Al colloids in lakes and rivers. We used a continuum of surface water bodies, from permafrost subsidence, small depressions and thaw ponds to large lakes and rivers that drain the Western Siberia Lowland (WSL), to assess OC, major and the trace element size distribution between the 20-mm, 5-mm, 1.2-mm, 0.45-mm, 0.22-mm, 0.025-mm and 1-kDa (~1.4 nm) size fractions. This approach allowed us to distinguish the organic and organo-ferric colloids that were responsible for the transport of trace elements in surface waters and address their evolution during possible physico-chemical and biological processes. Both conventionally dissolved (<0.22 mm) and low-molecular-weight (<1 kDa) fractions exhibited an order of magnitude decrease in DOC/Fe in the landscape continuum "depressions and permafrost subsidence ® thaw ponds ® thermokarst lakes ® streams ® rivers". Thermodynamic modeling and on-site size separation suggested that a number of trace elements (TEs), including alkaline earth elements and several micronutrients (Zn, Ba, Mn, and Ni), decreased the degree of their binding to DOM along the landscape continuum, whereas the majority of insoluble TEs (Al, Fe, Co, Cd, Cu, Pb, REEs, Th, and U) remained complexed with DOM in the LMW_{<1 kDa} fraction. Two primary sites of colloid generation included (i) ground vegetation and peat leaching, which supplied DOM complexes of divalent metals and organo-Al entities to thaw ponds and lakes; and (ii) Fe²⁺ oxidation and TE co-precipitation with Fe hydroxides in the presence of surface DOM at groundwater discharge sites within the riparian/hyporheic zones of rivers. Under a warming climate scenario, an increase in the thickness of the thawing depth will intensify the input of inorganic components from deep mineral horizons and possibly underground waters thus producing the enrichment of large lakes in Fe-rich colloids and particles. The speciation of divalent metal micronutrients (Cu, Ni, and Co) and toxic metals (Al, Cd, Pb, and U) that are complexed within DOM will most likely remain conservative. Overall, the WSL's surface water colloidal composition may shift from DOM-rich and DOM-Al-rich to Fe-rich, and the export of low-soluble trivalent and tetravalent hydrolysates from the soil to rivers will increase.

DOI: 10.1016/j.gca.2016.05.035

2016076455 Braverman, Michael (Wilfrid Laurier University, Cold Regions Research Centre, Waterloo, ON, Canada) and Quinton, William L. Hydrological impacts of seismic lines in the wetland-dominated zone of thawing, discontinuous permafrost, Northwest Territories, Canada: Hydrological Processes, 30(15), p. 2617-2627, illus. incl. 1 table, sketch map, 25 ref., July 15, 2016.

Intensive seismic exploration in the Northwest Territories began in the late 1960s. Since that time, the legacy of seismic surveys - i.e. straight lines cutting through boreal forest and tundra - has remained visible throughout northern Canada and Alaska. The removal of trees and compaction of the ground surface alter the thermophysical properties of the active (i.e. seasonally thawed) layer to such an extent that the underlying permafrost seriously degrades or even disappears completely. Such a transformation along linear corridors that cut indiscriminately across different terrain types with contrasting hydrological functions has potentially serious implications to the redistribution of water and energy within and among landscape units with feedbacks to permafrost thaw, land cover change and run-off generation. This paper characterizes the flow and storage of water and energy along a seismic cut line in the high boreal zone of discontinuous permafrost in order to improve the understanding of these processes, their interactions and hydrological implications. As such, this paper lays a conceptual foundation for the development of numerical models needed to predict the hydrological and thermal impact of seismic lines in this sensitive region. We used ground-penetrating radar and multi-year ground temperatures and water levels along a seismic line to estimate the degree of permafrost degradation below it. The seismic line studied extends from a permafrost-free wetland (flat bog), over a permafrost body (peat plateau) and into another permafrost-free wetland (channel fen). It was found that once thaw had lowered the permafrost table below the ground surface elevation of the flat bog and channel fen, the seismic line forms a hydrological connection between them. It was also shown that during the permafrost thaw process, seismic lines develop a perennially thawed layer (talik) between the overlying active layer and underlying permafrost and that the talik conveys water as a conduit throughout the year. The implications of such drainage through seismic lines and networks on basin drainage in peatland-dominated regions with discontinuous permafrost are also discussed. Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/hyp.10695

2016076435 Arp, Christopher D. (University of Alaska Fairbanks, Water and Environmental Research Center, Fairbanks, AK); Jones, Benjamin M.; Grosse, Guido; Bondurant, Allen C.; Romanovsky, Vladimir E.; Hinkel, Kenneth M. and Parsekian, Andrew D. Threshold sensitivity of shallow Arctic lakes and sublake permafrost to changing winter climate: Geophysical Research Letters, 43(12), p. 6358-6365, illus., 37 ref., June 28, 2016.

Interactions and feedbacks between abundant surface waters and permafrost fundamentally shape lowland Arctic landscapes. Sublake permafrost is maintained when the maximum ice thickness (MIT) exceeds lake depth and mean annual bed temperatures (MABTs) remain below freezing. However, declining MIT since the 1970s is likely causing talik development below shallow lakes. Here we show high-temperature sensitivity to winter ice growth at the water-sediment interface of shallow lakes based on year-round lake sensor data. Empirical model experiments suggest that shallow (1 m depth) lakes have warmed substantially over the last 30 years (2.4°C), with MABT above freezing 5 of the last 7 years. This is in comparison to slower rates of warming in deeper (3 m) lakes (0.9°C), with already well-developed taliks. Our findings indicate that permafrost below shallow lakes has already begun crossing a critical thawing threshold approximately 70 years prior to predicted terrestrial permafrost thaw in northern Alaska. Abstract Copyright (2016),. The Authors.

DOI: 10.1002/2016GL068506

2016080259 Mu Cuicui (Lanzhou University, College of Earth and Environmental Sciences, Lanzhou, China); Zhang Tingjun; Zhang Xiankai; Cao Bin; Peng Xiaoqing; Cao Lin and Su Hang. Pedogenesis and physicochemical parameters influencing soil carbon and nitrogen of alpine meadows in permafrost regions in the northeastern Qinghai-Tibetan Plateau: Catena (Giessen), 141, p. 85-91, illus. incl. sketch map, 52 ref., June 2016.

The variability of soil carbon and nitrogen and the lack of information regarding the properties of deep soils in alpine permafrost regions hinder our understanding of ecosystem responses to climate change. The objective of this study was to examine the effects of pedogenesis and soil physicochemical parameters on the distributions of soil carbon and nitrogen and their characteristics of alpine meadows in permafrost regions. The results showed that pedogenesis was an important factor in the distribution of soil organic carbon (SOC) and total nitrogen (TN) in both the active layers and deep soils. The average water-soluble organic carbon (WSOC) content in the permafrost layer was higher than that of the active layer, which implied that the carbon pool in the permafrost layer was easily decomposable. Soil pH was an important factor that influenced soil inorganic carbon (SIC), which was closely associated with SOC in deep soils. The significant negative relationships between the SIC, pH and C/N ratios in permafrost regions implied that SIC can play an important role in the turnover of SOM and TN. Abstract Copyright (2016) Elsevier, B.V.

DOI: 10.1016/j.catena.2016.02.020

2016074672 Walvoord, Michelle A. (U. S. Geological Survey, Lakewood, CO) and Kurylyk, Barret L. Hydrologic impacts of thawing permafrost; a review: Vadose Zone Journal, 15(6), 20 p., illus. incl. 3 tables, sketch map, 182 ref., June 2016.

Where present, permafrost exerts a primary control on water fluxes, flowpaths, and distribution. Climate warming and related drivers of soil thermal change are expected to modify the distribution of permafrost, leading to changing hydrologic conditions, including alterations in soil moisture, connectivity of inland waters, streamflow seasonality, and the partitioning of water stored above and below ground. The field of permafrost hydrology is undergoing rapid advancement with respect to multiscale observations, subsurface characterization, modeling, and integration with other disciplines. However, gaining predictive capability of the many interrelated consequences of climate change is a persistent challenge due to several factors. Observations of hydrologic change have been causally linked to permafrost thaw, but applications of process-based models needed to support and enhance the transferability of empirical linkages have often been restricted to generalized representations. Limitations stem from inadequate baseline permafrost and unfrozen hydrogeologic characterization, lack of historical data, and simplifications in structure and process representation needed to counter the high computational demands of cryohydrogeologic simulations. Further, due in part to the large degree of subsurface heterogeneity of permafrost landscapes and the nonuniformity in thaw patterns and rates, associations between various modes of permafrost thaw and hydrologic change are not readily scalable; even trajectories of change can differ. This review highlights promising advances in characterization and modeling of permafrost regions and presents ongoing research challenges toward projecting hydrologic and ecologic consequences of permafrost thaw at time and spatial scales that are useful to managers and researchers.

DOI: 10.2136/vzj2016.01.0010

2016080330 Helbig, Manuel (Université de Montréal, Département de Géographie, Montreal, QC, Canada); Pappas, C. and Sonnentag, O. Permafrost thaw and wildfire; equally important drivers of boreal tree cover changes in the Taiga Plains, Canada: Geophysical Research Letters, 43(4), p. 1598-1606, illus. incl. sketch maps, 69 ref., February 28, 2016.

Boreal forests cover vast areas of the permafrost zones of North America, and changes in their composition and structure can lead to pronounced impacts on the regional and global climate. We partition the variation in regional boreal tree cover changes between 2000 and 2014 across the Taiga Plains, Canada, into its main causes: permafrost thaw, wildfire disturbance, and postfire regrowth. Moderate Resolution Imaging Spectroradiometer Percent Tree Cover (PTC) data are used in combination with maps of historic fires, and permafrost and drainage characteristics. We find that permafrost thaw is equally important as fire history to explain PTC changes. At the southern margin of the permafrost zone, PTC loss due to permafrost thaw outweighs PTC gain from postfire regrowth. These findings emphasize the importance of permafrost thaw in controlling regional boreal forest changes over the last decade, which may become more pronounced with rising air temperatures and accelerated permafrost thaw. Abstract Copyright (2016), . American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2015GL067193

2016080146 Shang Wen (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Wu Xiaodong; Zhao Lin; Yue Guangyang; Zhao Yonghua; Qiao Yongping and Li Yuqiang. Seasonal variations in labile soil organic matter fractions in permafrost soils with different vegetation types in the central Qinghai-Tibet Plateau: in Soils and space and time (Sauer, D., editor; et al.), Catena (Giessen), 137, p. 670-678, illus. incl. 3 tables, sketch map, 58 ref., February 2016.

Labile soil organic matter (SOM) plays a crucial role in nutrient and carbon cycling, particularly in permafrost ecosystems. Understanding its variation is therefore very important. In the present study, we evaluated the seasonal patterns of labile SOM from April 2013 to March 2014 under alpine swamp meadow (ASM), meadow (AM), steppe (AS) and desert (AD) vegetation in permafrost regions of the China's Qinghai-Tibet Plateau. The fractions (0 to 10 cm depth) included dissolved organic carbon (DOC), light-fraction carbon (LFC) and nitrogen (LFN), and microbial biomass carbon (MBC) and nitrogen (MBN). These fractions showed dramatic seasonal patterns in ASM and AM soils, but were relatively stable in AD soil. Soil DOC concentrations in the ASM, AM, and AD soils increased from April to May 2013, then increased again from July to August 2013 and from February to March 2014. The LFC and LFN concentrations in all four vegetation types were higher from June to August 2013. The highest MBC and MBN concentrations in the ASM, AM, and AS soils all occurred in the summer and the ASM soil showed a second peak in October or November 2013. Seasonal changes in climatic factors, vegetation types, and permafrost features were great causes of labile SOM variations in this study. Throughout the entire sampling period, the ASM soil generally had the highest labile SOM, followed by the AM, AS, and AD soils; thus, the ASM soil is the best system conserving soil nutrient (especially labile fractions) and microbial activity. Correlation analysis indicated that these fractions were not related to soil moisture and temperature in AS or AD soils, but soil temperature and moisture were significantly related to MBC and MBN in AM soil and DOC in ASM soil. Thus, the response of the labile SOM fractions in this high-altitude permafrost soils to climate change depended strongly on vegetation types. Abstract Copyright (2016) Elsevier, B.V.

DOI: 10.1016/j.catena.2015.07.012

2016079060 Xiang Longwei (Chinese Academy of Sciences, Institute of Geodesy and Geophysics, Wuhan, China); Wang Hansheng; Steffen, Holger; Wu, Patrick; Jia Lulu; Jiang Liming and Shen Qiang. Groundwater storage changes in the Tibetan Plateau and adjacent areas revealed from GRACE satellite gravity data: Earth and Planetary Science Letters, 449, p. 228-239, illus. incl. sketch maps, 54 ref., September 1, 2016. Includes appendix.

Understanding groundwater storage (GWS) changes is vital to the utilization and control of water resources in the Tibetan Plateau. However, well level observations are rare in this big area, and reliable hydrology models including GWS are not available. We use hydro-geodesy to quantitate GWS changes in the Tibetan Plateau and surroundings from 2003 to 2009 using a combined analysis of satellite gravity and satellite altimetry data, hydrology models as well as a model of glacial isostatic adjustment (GIA). Release-5 GRACE gravity data are jointly used in a mascon fitting method to estimate the terrestrial water storage (TWS) changes during the period, from which the hydrology contributions and the GIA effects are effectively deducted to give the estimates of GWS changes for 12 selected regions of interest. The hydrology contributions are carefully calculated from glaciers and lakes by ICESat-1 satellite altimetry data, permafrost degradation by an Active-Layer Depth (ALD) model, soil moisture and snow water equivalent by multiple hydrology models, and the GIA effects are calculated with the new ICE-6G_C (VM5a) model. Taking into account the measurement errors and the variability of the models, the uncertainties are rigorously estimated for the TWS changes, the hydrology contributions (including GWS changes) and the GIA effect. For the first time, we show explicitly separated GWS changes in the Tibetan Plateau and adjacent areas except for those to the south of the Himalayas. We find increasing trend rates for eight basins: +2.46 ± 2.24 Gt/yr for the Jinsha River basin, +1.77 ± 2.09 Gt/yr for the Nujiang-Lancangjiang Rivers Source Region, +1.86 ± 1.69 Gt/yr for the Yangtze River Source Region, +1.14 ± 1.39 Gt/yr for the Yellow River Source Region, +1.52 ± 0.95 Gt/yr for the Qaidam basin, +1.66 ± 1.52 Gt/yr for the central Qiangtang Nature Reserve, +5.37 ± 2.17 Gt/yr for the Upper Indus basin and +2.77 ± 0.99 Gt/yr for the Aksu River basin. All these increasing trends are most likely caused by increased runoff recharges from melt water and/or precipitation in the surroundings. We also find that the administrative actions such as the Chinese Ecological Protection and Construction Project help to store more groundwater in the Three Rivers Source Region, and suggest that seepages from the Endorheic basin to the west of it are a possible source for GWS increase in this region. In addition, our estimates for GWS changes basically confirm previous results along Afghanistan, Pakistan, north India and Bangladesh, and clearly reflect the excessive use of groundwater. Our results will benefit the water resource management in the study area, and are of particular significance for the ecological restoration in the Tibetan Plateau.

DOI: 10.1016/j.epsl.2016.06.002

2016074453 Jiang, Yueyang (Purdue University, Department of Earth, Atmospheric, and Planetary Sciences, West Lafayette, IN); Zhuang, Qianlai; Sitch, Stephen; O'Donnell, Jonathan A.; Kicklighter, David; Sokolov, Andrei and Melillo, Jerry. Importance of soil thermal regime in terrestrial ecosystem carbon dynamics in the circumpolar north: Global and Planetary Change, 142, p. 28-40, illus. incl. 4 tables, 87 ref., July 2016.

In the circumpolar north (45-90°N), permafrost plays an important role in vegetation and carbon (C) dynamics. Permafrost thawing has been accelerated by the warming climate and exerts a positive feedback to climate through increasing soil C release to the atmosphere. To evaluate the influence of permafrost on C dynamics, changes in soil temperature profiles should be considered in global C models. This study incorporates a sophisticated soil thermal model (STM) into a dynamic global vegetation model (LPJ-DGVM) to improve simulations of changes in soil temperature profiles from the ground surface to 3 m depth, and its impacts on C pools and fluxes during the 20th and 21st centuries. With cooler simulated soil temperatures during the summer, LPJ-STM estimates ~ 0.4 Pg C yr^-1 lower present-day heterotrophic respiration but ~ 0.5 Pg C yr^-1 higher net primary production than the original LPJ model resulting in an additional 0.8 to 1.0 Pg C yr^-1 being sequestered in circumpolar ecosystems. Under a suite of projected warming scenarios, we show that the increasing active layer thickness results in the mobilization of permafrost C, which contributes to a more rapid increase in heterotrophic respiration in LPJ-STM compared to the stand-alone LPJ model. Except under the extreme warming conditions, increases in plant production due to warming and rising CO₂, overwhelm the enhanced ecosystem respiration so that both boreal forest and arctic tundra ecosystems remain a net C sink over the 21st century. This study highlights the importance of considering changes in the soil thermal regime when quantifying the C budget in the circumpolar north.

DOI: 10.1016/j.gloplacha.2016.04.011

2016074607 Karlsson, Emma (Stockholm University, Department of Environmental Science and Analytical Chemistry, Stockholm, Sweden); Gelting, Johan; Tesi, Tommaso; Dongen, Bart; Andersson, August; Semiletov, Igor P.; Charkin, Alexander; Dudarev, Oleg and Gustafsson, Orjan. Different sources and degradation state of dissolved, particulate, and sedimentary organic matter along the Eurasian Arctic coastal margin: Global Biogeochemical Cycles, 30(6), p. 898-919, illus. incl. 4 tables, sketch map, 139 ref., June 2016.

Thawing Arctic permafrost causes massive fluvial and erosional releases of dissolved and particulate organic carbon (DOC and POC) to coastal waters. Here we investigate how different sources and degradation of remobilized terrestrial carbon may affect large-scale carbon cycling, by comparing molecular and dual-isotope composition of waterborne high molecular weight DOC (>1 kD, aka colloidal OC), POC, and sedimentary OC (SOC) across the East Siberian Arctic Shelves. Lignin phenol fingerprints demonstrate a longitudinal trend in relative contribution of terrestrial sources to coastal OC. Wax lipids and cutins were not detected in colloidal organic carbon (COC), in contrast to POC and SOC, suggesting that different terrestrial carbon pools partition into different aquatic carrier phases. The D¹⁴C signal suggests overwhelmingly contemporary sources for COC, while POC and SOC are dominated by old C from Ice Complex Deposit (ICD) permafrost. Monte Carlo source apportionment (d¹³C, D¹⁴C) constrained that COC was dominated by terrestrial OC from topsoil permafrost (65%) and marine plankton (25%) with smaller contribution ICD and other older permafrost stocks (9%). This distribution is likely a result of inherent compositional matrix differences, possibly driven by organomineral associations. Modern OC found suspended in the surface water may be more exposed to degradation, in contrast to older OC that preferentially settles to the seafloor where it may be degraded on a longer timescale. The different sources which partition into DOC, POC, and SOC appear to have vastly different fates along the Eurasian Arctic coastal margin and may possibly respond on different timescales to climate change. Abstract Copyright (2016), . American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2015GB005307

2016076460 Bao, Huiyi (University of Tokyo, Department of Civil Engineering, Tokyo, Japan); Koike, Toshio; Yang Kun; Wang Lei; Shrestha, Maheswor and Lawford, Peter. Development of an enthalpy-based frozen soil model and its validation in a cold region in China: Journal of Geophysical Research: Atmospheres, 121(10), p. 5259-5280, illus. incl. 2 tables, sketch map, 56 ref., May 27, 2016.

An enthalpy-based frozen soil model was developed for the simulation of water and energy transfer in cold regions. To simulate the soil freezing/thawing processes stably and efficiently, a three-step algorithm was applied to solve the nonlinear governing equations: (1) a thermal diffusion equation was implemented to simulate the heat conduction between soil layers; (2) a freezing/thawing scheme used a critical temperature criterion to judge the phase status and introduced enthalpy and total water mass into freezing depression equation to represent ice formation/melt and corresponding latent heat release/absorption; and (3) a water flow scheme was employed to describe the liquid movement within frozen soil. In addition, a parameterization set of hydraulic and thermal properties was updated by considering the frozen soil effect. The performance of the frozen soil model was validated at point scale in a typical mountainous permafrost basin of China. An ice profile initialization method is proposed for permafrost modeling. Results show that the model can achieve a convergent solution at a time step of hourly and a surface layer thickness of centimeters that are typically used in current land surface models. The simulated profiles of soil temperature, liquid water content, ice content and thawing front depth are in good agreement with the observations and the characteristics of permafrost. The model is capable of continuously reproducing the diurnal and seasonal freeze-thaw cycle and simulating frozen soil hydrological processes. Abstract Copyright (2016), . American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2015JD024451

2016081227 Mengis, N. (GEOMAR-Helmholtz Centre for Ocean Research Kiel, Kiel, Germany); Martin, T.; Keller, D. P. and Oschlies, A. Assessing climate impacts and risks of ocean albedo modification in the Arctic: Journal of Geophysical Research: Oceans, 121(5), p. 3044-3057, illus. incl. 1 table, sketch map, 49 ref., May 2016.

The ice albedo feedback is one of the key factors of accelerated temperature increase in the high northern latitudes under global warming. This study assesses climate impacts and risks of idealized Arctic Ocean albedo modification (AOAM), a proposed climate engineering method, during transient climate change simulations with varying representative concentration pathway (RCP) scenarios. We find no potential for reversing trends in all assessed Arctic climate metrics under increasing atmospheric CO₂ concentrations. AOAM only yields an initial offset during the first years after implementation. Nevertheless, sea ice loss can be delayed by 25(60) years in the RCP8.5(RCP4.5) scenario and the delayed thawing of permafrost soils in the AOAM simulations prevents up to 40(32) Pg of carbon from being released by 2100. AOAM initially dampens the decline of the Atlantic Meridional Overturning and delays the onset of open ocean deep convection in the Nordic Seas under the RCP scenarios. Both these processes cause a subsurface warming signal in the AOAM simulations relative to the default RCP simulations with the potential to destabilize Arctic marine gas hydrates. Furthermore, in 2100, the RCP8.5 AOAM simulation diverts more from the 2005-2015 reference state in many climate metrics than the RCP4.5 simulation without AOAM. Considering the demonstrated risks, we conclude that concerning longer time scales, reductions in emissions remain the safest and most effective way to prevent severe changes in the Arctic. Abstract Copyright (2016), . American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2015JC011433

2016080885 Zorigt, Munkhtsetseg (National University of Mongolia, Ulan Bator, Mongolia); Kwadijk, Jaap; van Beek, Eelco and Kenner, Scott. Estimating thawing depths and mean annual ground temperatures in the Khuvsgul region of Mongolia: Environmental Earth Sciences, 75(10), Article 897, illus. incl. 4 tables, sketch map, 22 ref., May 2016.

Permafrost is an important component in the ecosystem and plays a key role in soil regime characteristics in high-altitude regions. Thawing depths and mean annual ground temperatures are the main parameters to conduct research on permafrost. Here we present the results of different modeling approaches for estimating thawing depths and mean annual ground temperatures in the Khuvsgul region of Mongolia. The aim of this study was to analyze the modeling approaches and determine what model best simulates the different characteristics of the soils. Moreover, this study investigates the factors that determine the best fit model approaches for certain conditions of the study area. For this study, the Stefan model was applied to estimate thawing depths and the TTOP and Kudryavtsev model approaches were applied for the estimations of mean annual ground temperatures. The estimations were performed at seven observational boreholes in the region. The evaluations show that model results are more sensitive to thermal and physical properties of the soil than the air temperatures for estimating thawing depths and mean annual ground temperatures. Copyright 2016 Springer-Verlag Berlin Heidelberg

DOI: 10.1007/s12665-016-5687-1

2016076010 Luo Dongliang (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, State Key Laboratory of Frozen Soil Engineering, Lanzhou, China); Wu Qingbai; Jin Huijun; Marchenko, Sergey S.; Lu Lanzhi and Gao Siru. Recent changes in the active layer thickness across the Northern Hemisphere: Environmental Earth Sciences, 75(7), Article 555, illus. incl. 2 tables, 61 ref., April 2016.

To better understand the ecological and hydrological responses to climatic and cryospheric changes, the spatiotemporal variations in the active layer thickness (ALT) need to be scrupulously studied. Based on more than 230 sites from the circumpolar active layer monitoring network, the spatiotemporal characteristics of the ALT across the northern hemisphere during 1990-2015 were investigated. Results indicate that the ALT exhibits substantial spatial variations across the northern hemisphere, ranging from approximately 30 cm in the arctic and subarctic regions to greater than 10 m in the mountainous permafrost regions at mid-latitudes. Regional averages of ALT are 48 cm in Alaska, 93 cm in Canada, 164 cm in the Nordic countries (including Greenland and Svalbard) and Switzerland, 330 cm in Mongolia, 476 cm in Kazakhstan, and 230 cm on the Qinghai-Tibetan Plateau (QTP), respectively. In Russia, the regional averages of ALT in European North, West Siberia, central Siberia, northeast Siberia, Chukchi, and Kamchatka are 110, 92, 69, 61, 53 and 60 cm, respectively. Increasing trends of ALT were not uniformly present in the observational records. Significant changes in the ALT were observed at 73 sites, approximately 43.2 % of the investigated 169 sites that are available for statistical analysis. Less than 25 % Alaskan sites and approximately 33 % Canadian sites showed significant increase in the ALT. On the QTP, almost all the sites showed significant ALT increases. Insignificant increase and even decrease in the ALT were observed in some parts of the northern hemisphere, e.g., Mongolia, parts of Alaska and Canada. The air and ground temperatures, vegetation, substrate, microreliefs, and soil moisture in particular, play decisive roles in the spatiotemporal variations in the ALT, but the relationships among each other are complicated and await further studies. Copyright 2016 Springer-Verlag Berlin Heidelberg

DOI: 10.1007/s12665-015-5229-2

2016080835 Zhang Mingli (Chinese Academy of Sciences, Cold and Arid Regions Environmental Engineering Research Institute, Lanzhou, China); Wen Zhi; Xue Ke; Chen Liangzhi and Li Desheng. A coupled model for liquid water, water vapor and heat transport of saturated-unsaturated soil in cold regions; model formulation and verification: Environmental Earth Sciences, 75(8), Article 701, illus. incl. 5 tables, 72 ref., April 2016.

In cold and arid regions, vapor movement and water flow are crucial to thermal-moisture dynamics of the active layer and control the soil microbial activity, plant growth and engineering applications. Although it is widely recognized that both liquid and water vapor movement are fundamental factors in the quantification of soil mass and energy balance, their computation is still rarely considered in most models or practical applications. Moreover, previous studies on the movement of moisture migration in unsaturated frozen soil are limited. This study was conducted to: (a) implement a fully coupled numerical model that includes water migration in both the vapor and liquid phases and heat transfer by means of conduction, convection, latent heat of vapor diffusion and phase change effects. (b) Verify the numerical model with detailed field monitoring data. (c) Analyze the role of water flow and vapor diffusion in the heat and mass transport. The result showed that the numerical model was able to fully calculate the coupled soil mass and energy budget. Thermal conduction dominated the heat transport in the deeper layer (below 75 cm) in permafrost regions, while the impact of water movement on heat in summer was significant in shallow ground. Soil water was transported by both liquid water and water vapor and water vapor contributed more than 15 % of the water flux at all depths. Vapor and liquid water transport play an important role in soil mass and energy transfer, especially for the shallow surface. It is necessary to consider the coupled liquid water, water vapor, and heat transport in predictions of soil water and heat dynamics in permafrost regions. Copyright 2016 Springer-Verlag Berlin Heidelberg

DOI: 10.1007/s12665-016-5499-3

2016076034 Sjoberg, Ylva (Stockholm University, Department of Physical Geography, Stockholm, Sweden); Coon, Ethan; Sannel, A. Britta K.; Pannetier, Romain; Harp, Dylan; Frampton, Andrew; Painter, Scott L. and Lyon, Steve W. Thermal effects of groundwater flow through subarctic fens; a case study based on field observations and numerical modeling: Water Resources Research, 52(3), p. 1591-1606, illus. incl. 3 tables, 51 ref., March 2016.

Modeling and observation of ground temperature dynamics are the main tools for understanding current permafrost thermal regimes and projecting future thaw. Until recently, most studies on permafrost have focused on vertical ground heat fluxes. Groundwater can transport heat in both lateral and vertical directions but its influence on ground temperatures at local scales in permafrost environments is not well understood. In this study we combine field observations from a subarctic fen in the sporadic permafrost zone with numerical simulations of coupled water and thermal fluxes. At the Tavvavuoma study site in northern Sweden, ground temperature profiles and groundwater levels were observed in boreholes. These observations were used to set up one- and two-dimensional simulations down to 2 m depth across a gradient of permafrost conditions within and surrounding the fen. Two-dimensional scenarios representing the fen under various hydraulic gradients were developed to quantify the influence of groundwater flow on ground temperature. Our observations suggest that lateral groundwater flow significantly affects ground temperatures. This is corroborated by modeling results that show seasonal ground ice melts 1 month earlier when a lateral groundwater flux is present. Further, although the thermal regime may be dominated by vertically conducted heat fluxes during most of the year, isolated high groundwater flow rate events such as the spring freshet are potentially important for ground temperatures. As sporadic permafrost environments often contain substantial portions of unfrozen ground with active groundwater flow paths, knowledge of this heat transport mechanism is important for understanding permafrost dynamics in these environments. Abstract Copyright (2016), . American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2015WR017571

2016072042 Gopp, Natalia V. (Russian Academy of Sciences, Siberian Branch, Institute of Soil Science and Agrochemistry, Novosibirsk, Russian Federation). Soils of the southwestern part of the Dzhulukul Depression in the Altai Republic: Eurasian Soil Science, 48(6), p. 567-577, 26 ref., June 2015. Based on Publisher-supplied data.

Soils of the southwestern part of the Dzhulukul Depression in Ulagan district of the Altai Republic have been studied. They belong to two soil divisions: Al-Fe-humus soils (with various types of podburs) and iron-metamorphic soils (rzhavozems). The soils within the eluvial part of the studied catena-iron-illuvial soddy podburs-are developed from the residuum of magmatic and metamorphic rocks with high (up to 80 vol %) content of gravels and coarse rock fragments. Their high porosity favors downward migration and precipitation of humus-iron compounds on the surface of gravels and mineral grains in the illuvial horizon. The soils of the accumulative part of the catena-permafrost-affected raw-humus pod-burs and gleyic podburs)-are developed from moraine deposits of loamy-sandy texture with up to 30 vol % of gravels. In these soils, the features of the Al-Fe-humus migration are weakly pronounced; the soils are underlain by the waterproof frozen horizon (permafrost), have high humus content, and have thixotropic properties in the lower horizons. Their reaction is slightly acid to neutral, and their base saturation is up to 80%. These characteristics do not meet the criteria of podburs as defined in the new Russian soil classification system. Their origin may be related to the local mixing of weathering products of different bedrock materials, including magmatic, metamorphic, and sedimentary rocks during the deposition of moraine sediments. Iron-metamorphic soils (rzhavozems) are formed on convex parts of slopes from the residuum and colluvial derivatives of magmatic and metamorphic rocks (granite, metamorphic slates, red-colored sandstone, etc.). A distinctive feature of these soils is their ocherous-brown color and a considerable content of gravels in the entire profile. The chemical properties of rzhavozems resemble those of the Al-Fe-humus soils of automorphic positions: acid and slightly acid reaction, low base saturation, and a relatively high content of organic carbon in the organic and mineral horizons. Copyright 2015 Pleiades Publishing, Ltd.

DOI: 10.1134/S1064229315060046

2016071943 Yamamoto, Yuko (Swiss Federal Institute of Technology, Institute of Technology, Zurich, Switzerland) and Springman, Sarah M. Axial compression stress path tests on artificial frozen soil samples in a triaxial device at temperatures just below O°C: Canadian Geotechnical Journal = Revue Canadienne de Géotechnique, 51(10), illus. incl. 5 tables, 135 ref., October 2014.

This paper aims to assess the characteristics of the strength and creep properties of frozen soil under triaxial stress conditions at temperatures close to the thawing point. A series of triaxial constant rate of strain (CRS) and constant stress creep (CSC) tests was carried out in axial compression on artificially frozen soil samples at temperatures between -3.0 and -0.3 °C. Acoustic emissions, with a frequency range of 100-1000 kHz, were measured using a wide-band piezoelectric sensor to understand the mechanisms of the deformation behaviour and microstructural effects that control the response of the frozen soil specimens during the tests, especially at yield and approaching failure. The test results showed that the influence of a temperature increase close to the thawing point led to reduced shear strength and increased minimum axial strain rate. The test results were compared with data from similar experiments on artificial frozen and alpine permafrost specimens obtained from a past research project. It was observed that the acoustic emission response indicates a change in the physical process of deformation between microcrack formation and the reorientation of ice granules, depending on the strain rate.

URL: http://www.nrcresearchpress.com/doi/full/10.1139/cgj-2013-0257#ttl8

2016080137 Sauer, D.; Poch, Rosa M. and Stahr, K., editors. Soils and space and time: Catena (Giessen), 137, p. 581-685, illus., February 2016. Individual papers are cited separately.

2016072041 Karavaeva, N. A. (Russian Academy of Science, Institute of Geography, Moscow, Russian Federation) and Sokolova, T. A. Soils of slopes in the taiga zone of the Middle Ob reaches: Eurasian Soil Science, 48(6), p. 555-566, 38 ref., June 2015. Based on Publisher-supplied data.

The morphology, chemical properties, composition of phyllosilicates, as well as their transformation in loamy soils developing on slopes of ridges of the Vakh Upland in Western Siberia, are discussed. Data on two soil profiles - gleyic svetlozem of the middle slope and podzolized gleyzem of the footslope - are presented. Both soils have an acid reaction. The textural differentiation is weakly pronounced in the gleyic svetlozem and more pronounced in the podzolized gleyzem. The soils differ in their cryological conditions. The thawing depth in the svetlozem is about 60-70 cm, and the lower part of the profile to a depth of 3.2 m largely remains in the frozen state. Its complete thawing is only possible during the warm climatic cycles. This is a seasonally frozen soil with the long-lasting frozen state. It is characterized by the thick cryometamorphic (CRM) horizon. The gleyzem is a "normal" seasonally frozen soil with complete thawing of seasonal frost in summer. The CRM horizon is absent in its profile. The alteration of clay minerals in the soil profiles includes their partial dissolution, the formation of soil chlorites, and the transformation of illite into more labile structures. In the upper horizons of both soils, this transformation proceeds through the stage of mixed-layered illite-smectites. In the gleyzem, it reaches a more advanced stage of the formation of beidellite. The cryometamorphic horizons are specified by some amorphization of phyllosilicates and, probably, by the partial dissolution of their crystal lattices under the impact of frequent zero-temperature transitions and cryogenesis in the frozen state. Copyright 2015 Pleiades Publishing, Ltd.

DOI: 10.1134/S1064229315060058

2016073758 Dudarev, O. V. (Russian Academy of Sciences, Ilyichev Pacific Oceanological Institute, Vladivostok, Russian Federation); Charkin, A. N.; Shakhova, Natalia E.; Semiletov, Igor P.; Sergienko, V. I.; Pipko, I. I.; Pugach, S. P. and Chernykh, D. V. Peculiarities of the present-day morpholithogenesis on the Laptev Sea shelf; Semenovskaya shoal (Vasema Land): Doklady Earth Sciences, 462(1), p. 510-516, illus. incl. 3 tables, 5 ref., May 2015.

DOI: 10.1134/S1028334X15050116

2016072351 Jamshidi, Reza Jolous (Dalhousie University, Department of Civil and Resource Engineering, Halifax, NS, Canada) and Lake, Craig B. Hydraulic and strength properties of unexposed and freeze-thaw exposed cement-stabilized soils: Canadian Geotechnical Journal = Revue Canadienne de Géotechnique, 52(3), p. 283-294, illus. incl. 4 tables, 39 ref., March 2015.

A total of 108 specimens were prepared to examine the hydraulic performance and strength performance of nine different cement-stabilized soils under unexposed and freeze-thaw exposed conditions. Specimens from each mix design were evaluated under two levels of curing conditions (i.e., immature versus mature). Hydraulic conductivity and unconfined compressive strength (UCS) measurements were performed to assess changes in the performance of specimens after 12 cycles of freezing at -10 ± 1 °C and thawing at 22 ± 1 °C. Measured mass losses of the specimens from a standard brushing test were also monitored at different freeze-thaw cycles, and results were compared with the changes in the hydraulic performance for each mix design. Hydraulic conductivity measurements on unexposed mature specimens showed that the lowest values likely occurred at water contents slightly wet of optimum water content (OWC). The UCS values showed a general decreasing trend with the increase in the water content for both immature and mature specimens under unexposed conditions. After freeze-thaw exposure, specimens showed minor reductions as well as increases of up to 5250 times in hydraulic conductivity values. Increases of up to 14% and reductions of up to 58% in compressive strength were also observed, compared with unexposed conditions. For most cases, mature specimens resulted in a higher degree of damage compared with immature specimens. Results from the brushing tests showed this test method is not a suitable indicator for predicting changes in the hydraulic performance of cement-stabilized soils. Hydraulic conductivity measurements after a period of post-exposure healing showed damaged specimens have some potential in recovering parts of the increased hydraulic conductivity value due to the healing process.

DOI: 10.1139/cgi-2014-0100

2016073702 Kurchatova, A. N. (Russian Academy of Sciences, Siberian Branch, Institute of the Cryosphere, Tyumen, Russian Federation); Mel'nikov, V. P. and Rogov, V. V. Gas-bearing ice crystallites in clayey deposits: Doklady Earth Sciences, 459(2), p. 1510-1513, illus., 12 ref., December 2014.

This work is dedicated to gas-bearing empty ice crystallites 100-500 mm in size, which were found for the first time in Paleogene diatomic clay in the upper part of the frozen sequence of Western Siberia. The spherical, caselike, and splintered crystallites with hexagonal and curved faces are not related to relict gas hydrates and are the results of shift deformations of plastic frozen clayey deposits under degassing of the above Cenomanian rocks. These data should be taken into account in modeling the fluid dynamics and geodynamics of the frozen sequences, including the shallow shelf of the Arctic seas. Copyright 2014 Pleiades Publishing, Ltd.

DOI: 10.1134/S1028334X14120277

2016072970 Watanabe, Kunio (Mie University, Graduate School of Bioresources, Tsu, Japan) and Osada, Yurie. Comparison of hydraulic conductivity in frozen saturated and unfrozen unsaturated soils: Vadose Zone Journal, 15(5), 7 p., illus. incl. 1 table, 43 ref., May 2016.

Understanding the hydraulic conductivity of frozen soils near melting temperature is important in agricultural management and water balance calculation in cold regions and in the use of artificial ground freezing techniques. However, measurement of the hydraulic conductivity of frozen soils has been limited. Therefore, it is often estimated from the unsaturated hydraulic conductivity of unfrozen soil using temperature and the Clausius-Clapeyron equation, with inadequate validation. In this study, we simultaneously measured the unfrozen water content and hydraulic conductivity of three frozen soils by passing water through them and compared the results with water characteristic curves and unsaturated hydraulic conductivities of the unfrozen soils determined using the evaporation method. Using measured temperature data and water characteristic curves, the Clausius-Clapeyron equation underestimated unfrozen water contents in the frozen soils, which also resulted in underestimation of hydraulic conductivities, particularly near melting temperature. However, the unfrozen and frozen soils had similar hydraulic conductivities when their liquid water contents were the same. The hydraulic conductivity of frozen soil should be estimated from that of unfrozen soil based on the liquid (unfrozen) water content instead of the temperature.

DOI: 10.2136/vzj2015.11.0154

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2016077731 Eppelbaum, Lev V.; Kutasov, Izzy and Pilchin, Arkady N. Applied geothermics: in the collection Lecture notes in Earth system sciences. Springer, Berlin, Germany, 751 p., illus., 2014. ISBN: 978-3-642-34022-2; 978-3-642-34023-9.

This book describes origin and characteristics of the Earth's thermal field, thermal flow propagation and some thermal phenomena in the Earth. Description of thermal properties of rocks and methods of thermal field measurements in boreholes, underground, at near-surface conditions enables to understand the principles of temperature field acquisition and geothermal model development. Processing and interpretation of geothermal data are shown on numerous field examples from different regions of the world. The book warps, for instance, such fields as analysis of thermal regime of the Earth's crust, evolution and thermodynamic conditions of the magma-ocean and early Earth atmosphere, thermal properties of permafrost, thermal waters, geysers and mud volcanoes, methods of Curie discontinuity construction, quantitative interpretation of thermal anomalies, examination of some nonlinear effects, and integration of geothermal data with other geophysical methods. This book is intended for students and researchers in the field of Earth Sciences and Environment studying thermal processes in the Earth and in the subsurface. It will be useful for specialists applying thermal field analysis in petroleum, water and ore geophysics, environmental and ecological studies, archaeological prospection and climate of the past.

DOI: 10.1007/978-3-642-34023-9

2016079385 Liu Changling (China Geological Survey, Qingdao Institute of Marine Geology, Qingdao, China); Meng Qingguo and Ye Yuguang. Measurement of gas hydrate by laser Raman spectrometry: in Natural gas hydrates; experimental techniques and their applications (Ye Yuguang, editor; et al.), in the collection Springer geophysics. Springer, Berlin, Germany, p. 327-365, 51 ref., 2013.

Raman spectrometry is a powerful tool for gas hydrate researches to provide vital information regarding the structure of the hydrate, hydrate composition, and cage occupancy. This chapter begins with discussing the basic knowledge and application of laser Raman spectrometry and then, giving the techniques and methods which have been developed in our laboratory for different experiments of gas hydrate with Raman. The techniques and methods are used for measuring hydration number of methane hydrate prepared under different conditions; investigating the Raman spectra characteristics of air, nitrogen, and oxygen hydrates; and observing methane hydrate dissociation in sediments with different particle sizes. Observation of the microprocesses of hydrate formation and dissociation is also carried out based on a low-temperature high-pressure device for in situ Raman detection. The methods are also successfully used to determinate the natural gas hydrate samples collected from Shenhu area of the South China Sea and from the Qilian Mountain permafrost area, respectively, providing microscopic evidence for the existence of gas hydrates in the sediments.

DOI: 10.1007/978-3-642-31101-7_12

2016079393 Chen Qiang (China Geological Survey, Qingdao Institute of Marine Geology, Qingdao, China); Diao Shaobo and Ye Yuguang. Detecting hydrate in porous media using electrical resistance: in Natural gas hydrates; experimental techniques and their applications (Ye Yuguang, editor; et al.), in the collection Springer geophysics. Springer, Berlin, Germany, p. 127-140, 33 ref., 2013.

Natural gas hydrate synthesized in the porous medium is hardly observed by naked eyes, so an indirect technique has to be employed to research the characteristics of hydrates and the relevant reactions. Electrical resistance detection is one of the most important methods to investigate the hydrates formation and dissociation processes. A lot of experiments have been done to clarify the relationship between the electrical resistance variation and hydrates thermodynamic or kinetics properties. In this chapter, three main aspects of electrical resistance application in hydrate experiments are discussed, including dividing different stages of hydrate formation or dissociation process reflected by electrical resistance variation, establishing hydrate nucleation theoretical model based on electrical resistance data, and the determination of hydrate saturation in porous-medium system.

DOI: 10.1007/978-3-642-31101-7_4

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2016075560 Jia, Yiaoli (Ohio State University, School of Earth Sciences, Division of Geodetic Science, Columbus, OH); Shum, C. K.; Jia, Yuanyuan; Kim, Jin Woo and Kuo, Chung-Yen. Study of the northern Qinghai-Tibetan Plateau permafrost active layer depth rate using satellite geodetic observations [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract G33B-1139, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The Tibetan Plateau is the world's largest and the highest plateau with distinct and competing surface and subsurface processes. It is the Third Pole and the World Water Tower, owing to its vast ice reservoir with the largest number of glaciers in the world, and covered by a large (1.3 to 1.6 million km²) layer of discontinuous and sporadic alpine permafrost. The thawing over Tibetan Plateau permafrost regions is thought to be more severe compared with other high latitude permafrost regions by the fact that the permafrost is warm. During the past few decades, 82% of Tibetan Plateau glaciers have retreated and 10% permafrost has degraded. The overall mean active layer depth (ALD) rate increase over the Plateau is 1.4 cm yr^-1, 1980-2001, based on model studies and comparison with in situ borehole data. Here we report on the work in progress to quantify ALD rate increase in the northern Tibetan Plateau near the Tibetan national highway, using multi-band SAR/InSAR for improved the thermokarst surface classification, Envisat radar altimetry and ALOS-1 InSAR observed land subsidence, ALD modeling for the various thermokarst surface to relate to subsidence measurements, and the associated validations using available in situ borehole subsidence measurements.

2016075314 Murphy, M. J. (University of Oxford, Department of Earth Sciences, Oxford, United Kingdom); Pogge von Strandmann, P.; Porcelli, D.; Katchinoff, Joachim A.; Moreras Marti, Arola; Hirst, Catherine A.; Andersson, Per S. and Maximov, T. C. Assessing silicate weathering in permafrost-dominated catchments using lithium isotopes; the Lena River, Siberia [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract EP12B-08, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Rising global temperatures have the potential to influence the Earth's climate feedback cycles due to permafrost thawing, altering the freshwater input and trace metal and carbon fluxes into the ocean and atmosphere. Riverine lithium isotope ratios (d⁷Li) are a tracer of silicate weathering processes, which are key in the removal of atmospheric CO₂ over geological timescales. Despite this, little is known about the effects of permafrost thawing on d⁷Li variations. Strong seasonal changes in the thawed active layer thickness dictate surficial water flow paths, which may influence intra-annual riverine d⁷Li signatures. We present a study of the dissolved d⁷Li from the large permafrost-dominated watersheds of the Lena River (Siberia), which drain into the Arctic Ocean. This work comprises a temporal study during the May 2015 spring flood, from ice breakup through peak flooding, thus monitoring changes in water-rock and water-soil interaction, both processes that control weathering and hence Li isotopes. Before riverine ice started to break up, high [Li] are observed as the river signature is governed by winter base flow conditions. As the river ice breaks up, surface runoff flows over the impermeable permafrost, interacting with leaf litter, diluting the [Li]. We compare d⁷Li over the spring flood period with a greater spatial study conducted over two summer field seasons (2012/2013) of the main Lena River channel and its tributaries, which drain a variety of lithologies/topographies. During the summer, the thawed active layer promotes deeper water flow paths, greater water-rock interaction and enhanced secondary minerals formation which preferentially take up ⁶Li. Summer riverine d⁷Li typically fall between +14.5 ppm to +28.5 ppm, with rivers draining the Central Siberian Plateau typically exhibiting high [Li], but similar d⁷Li to rivers draining the Verkhoyansk Mountain Range. Overall, this study demonstrates how Li isotopes respond to weathering in a permafrost-dominated region, and provides rates on how quickly water-rock interaction can affect silicate weathering.

2016074051 Natali, Susan (Woods Hole Research Center, Falmouth, MA); Mauritz, Marguerite; Pegoraro, Elaine and Schuur, Edward. Permafrost thaw, soil moisture and plant community change alter organic matter decomposition in Alaskan tundra [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC13K-08, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Climate warming in arctic tundra has been associated with increased plant productivity and a shift in plant community composition, specifically an increase in shrub cover, which can impact soil organic matter through changes in the size and composition of the leaf litter pool. Shifts in litter quantity and quality will in turn interact with changes in the soil environment as the climate continues to warm. We examined the effects of permafrost thaw, soil moisture changes, and plant community composition on leaf litter decomposition in an upland tundra ecosystem in Interior Alaska. We present warming and drying effects on decomposition rates of graminoid-dominated and shrub-dominated leaf litter mixtures over three years (2 cm depth), and annual decomposition of a common cellulose substrate (0-10 cm and 10-20 cm) over five years at a permafrost thaw and soil drying experiment. We expected that warming and drying would increase decomposition, and that decomposition would be greater in the shrub litter than in the graminoid litter mix. Decomposition of Betula nana, the dominant shrub, was 50% greater in the shrub-dominated litter mix compared to the graminoid-dominated litter. Surprisingly, there was no significant difference in total litter mass loss between graminoid and shrub litter mixtures, despite significant differences in decomposition rates of the dominant plant species when decomposed alone and in community mixtures. Drying decreased decomposition of B. nana and of the shrub community litter overall, but after two years there was no detected warming effect on shrub-community decomposition. In contrast to leaf litter decomposition, both warming and drying increased decomposition of the common substrate. Warming caused an almost twofold increase in cellulose decomposition in surface soil (0-10 cm), and drying caused a twofold increase in cellulose decomposition from deeper organic layer soils (10-20 cm). These results demonstrate the importance of interactions among temperature, moisture and vegetation changes on organic matter decomposition, and the potential for increased plant productivity and vegetation changes to alter the size and composition of the soil organic matter pool.

2016071770 Coolen, Marco J. L. (Woods Hole Oceanographic Institution, Chemistry and Geochemistry Department, Woods Hole, MA); Orsi, William D. and Spivak, Amanda. Gene expression dynamics in thawing permafrost soils [abstr.]: in Goldschmidt abstracts 2014, V.M. Goldschmidt Conference - Program and Abstracts, 24, p. 458, 4 ref., 2014. Meeting: Goldschmidt 2014, June 8-13, 2014, Sacramento, CA.

2016075977 Lu Zhengquan (China Geological Survey, Oil & Gas Survey, Beijing, China); Cai Junjun; Sun Qing; Wang Ting; Tang Shiqi and Tan Panpan. Gas-hydrate-associated carbonates and their implications in the Qilian Mountain permafrost: in Proceeding of the Twenty-fourth (2014) international ocean and polar engineering conference (Chung, Jin S., editor; et al.), The Proceedings of the ... International Offshore and Polar Engineering Conference, 24, Volume 1, p. 10-14, 2014. Meeting: Twenty-fourth international ocean and polar engineering conference, June 15-20, 2014, Busan, South Korea. Based on Publisher-supplied data.

2016075979 Sun Zhongjun (Chinese Academy of Geological Sciences, Institute of Geophysical & Geochemical Exploration, Langfang, China); Han Ziye; Fang Hui; Yang Zhibin; Qin Aihua; Zhang Fugui; Zhou Yalong and Zhang Shunyao. Natural thermoluminescence prospecting of gas hydrate in the Qilian Mountains permafrost, Qinghai: in Proceeding of the Twenty-fourth (2014) international ocean and polar engineering conference (Chung, Jin S., editor; et al.), The Proceedings of the ... International Offshore and Polar Engineering Conference, 24, Volume 1, p. 34-39, 2014. Meeting: Twenty-fourth international ocean and polar engineering conference, June 15-20, 2014, Busan, South Korea. Based on Publisher-supplied data.

2016075978 Wen Huaijun (Qinghai Bureau of Coal Geology, Qinghai, China); Wei Liyang; Guo Jinning; Wang Jinping; Li Yonghong; Chen Xin; Zhang Shaolin; Wang Weichao and Fan Haijun. Exploration and identification of gas hydrate in Muli permafrost: in Proceeding of the Twenty-fourth (2014) international ocean and polar engineering conference (Chung, Jin S., editor; et al.), The Proceedings of the ... International Offshore and Polar Engineering Conference, 24, Volume 1, p. 29-33, 2014. Meeting: Twenty-fourth international ocean and polar engineering conference, June 15-20, 2014, Busan, South Korea. Based on Publisher-supplied data.

2016077907 Walker, Jesse (Louisiana State University, Department of Geography, Baton Rouge, LA) and McGraw, Molly. Tapped lakes as sediment traps in an Arctic delta: in Sediment dynamics from the summit to the sea (Jun Xu, Y., editor; et al.), Proceedings - International Association of Hydrological Sciences, 367, p. 407-412, illus. incl. 1 table, sketch maps, 9 ref., 2015. Meeting: ICCE 2014; international symposium on Sediment dynamics, Dec. 11-14, 2014, New Orleans, LA.

Lakes within the Colville River delta in northern Alaska, USA, vary in size from small ponds created by ice-wedge growth to thaw lakes that are as much as three kilometres long and ten metres deep. As the river migrates, lake edges are breached and the lakes are drained. Such lake tapping is aided by permafrost thaw and ice wedge melt and, in the case of the larger lakes, by wave action within them. Once a lake is tapped, it drains rapidly creating a deep scour hole at its entrance and from then on it is subject to the varying stages and discharge of the river. During flooding, when the river is transporting its largest amount of sediment, the tapped lakes become settling basins and rapidly fill. The Colville River delta has lakes in all stages from freshly breached to those that are now being destroyed by channel migration.

URL: http://www.proc-iahs.net/367/407/2015/piahs-367-407-2015.pdf

2016078969 Dalbec, Aubrey Charlotte (Northern Illinois University, Department of Geography, DeKalb, IL) and Konen, Michael. Pedology, sedimentology, and geomorphology of ice walled lake plains and associated superimposed landforms in northern Illinois [abstr.]: in Geological Society of America, North-Central Section, 50th annual meeting, Abstracts with Programs - Geological Society of America, 48(5), Abstract no. 18-4, 2016. Meeting: Geological Society of America, North-Central Section, 50th annual meeting, April 18-19, 2016, Champaign, IL.

More than 2000 Ice Walled Lake Plains (IWLP) have been mapped in Illinois. Many of the larger IWLP have superimposed landforms (SIL) which occur as elevated circular rims with interior depressions. The origin of these superimposed landforms has not been studied in detail. The pedologic, sedimentologic and geomorphic characteristics of IWLP and associated SIL were investigated. Morphometric properties of 66 superimposed landforms were performed using ArcGIS, and compared to possible modern glacial and periglacial analogs. We interpreted the superimposed landforms to be relict pingos that formed as permafrost aggraded into drained Ice Walled Lakes. This supports the existence of past permafrost in the study area, and can be used to aid in paleo-climatic reconstructions. Soil geomorphic relationships changed systematically across IWLPs and superimposed landforms.

DOI: 10.1130/abs/2016NC-275600

2016072631 Dziekan, Mitchell R. (University of Toledo, Department of Environmental Sciences, Toledo, OH); Fisher, Timothy G.; Horton, Jennifer and Loope, Henry M. Melt-out time lag, and its impact on assessing ages of Quaternary events [abstr.]: in Geological Society of America, North-Central Section, 50th annual meeting, Abstracts with Programs - Geological Society of America, 48(5), Abstract no. 3-5, 2016. Meeting: Geological Society of America, North-Central Section, 50th annual meeting, April 18-19, 2016, Champaign, IL.

The radiocarbon dating of basal sediments from kettle lakes is a common method used for assigning ages to deglacial events. Early studies suggested that these basins experience a 1,000 - 5,000 year lag to allow for pedogenesis, plant succession, and permafrost thaw before organic accumulation can begin. Recent studies suggest lags may vary locally due to differences in the extent of permafrost, water drainage, and burial conditions. For example, vegetation studies in the Yukon report that transitions from tundra to spruce forest result in a 120 year lag (Birks, 1980). Additionally, kettles in northern Michigan related to the Marquette readvance record a ~ 500 year lag (Derouin et al., 2007). In Poland, kettles along the same ice margin recorded lag times between a few hundred, to thousands of years (Blaszkiewicz, 2011). Recently in Michigan and Indiana, Horton (2015) proposed a younger date for the Saginaw Lobe's Sturgis Moraine by 2,000 years. An oldest age of 13.7 ± 80 ka ¹⁴C yr BP came from the basal sediments (pebbly sand) of three scour lakes within tunnel channels that extend past the moraine and are overlaid by outwash fans. These lakes were not expected to have experienced any lag time as they are interpreted to have formed from glaciofluvial scour, rather than melt-out of a buried ice block. Fullerton (1980) had previously assigned an age to the Sturgis Moraine between 16.1 - 15.5 ka ¹⁴C yr BP from radiocarbon ages similar to those generated by Horton, but he assumed a lag of 2,000 years. If Fullerton's age is correct, these scour lakes must have experienced a lag. To test this, Meteer Lake kettle, 6 km in front of the Sturgis Moraine near Howe, IN, was cored. Geomorphically, the kettle lies within a collapsed tunnel channel system younger than adjacent Saginaw and Huron-Erie Lobe outwash flow channels. Wood from basal sands in Meteer Lake gave a radiocarbon age of 13.4 ± 75 ka ¹⁴C BP. This one date suggests an even greater lag than Horton's ages. Due to evidence of variable lag times along one ice margin in Poland, the single age of Meteer Lake and the uncertain origin of the tunnel channels, additional and different types of lakes associated with the Sturgis Moraine are being cored. Along with OSL dating of kettle and outwash sediments, more dates from a variety of depositional environments should allow for better understanding of this time lag.

DOI: 10.1130/abs/2016NC-275530

2016078998 Farmer, Alison (Michigan State University, Department of Geography, Environment and Spatial Sciences, East Lansing, MI); Grove, Leslie and Schaetzl, Randall. Luminescence ages on a kame delta constrain the glacial retreat from central lower Michigan [abstr.]: in Geological Society of America, North-Central Section, 50th annual meeting, Abstracts with Programs - Geological Society of America, 48(5), Abstract no. 20-19, 2016. Meeting: Geological Society of America, North-Central Section, 50th annual meeting, April 18-19, 2016, Champaign, IL.

In association with a freshman Honors Seminar at Michigan State University, we studied two small kame deltas in north-central Lower Michigan. Only recently identified, the deltas provide key evidence for a previously unknown proglacial lake (Glacial Lake Roscommon) in this broad, sandy, interlobate upland. Our goal was to document these deltas and characterize their geomorphology. Both deltas are composed of well-sorted sands with little gravel. Samples taken across the deltas, from depths of up to 1.5 m, show little variation in texture, aside from a general fining toward their outer margins. Gullies on the outer margins of both deltas probably postdate the formation of the deltas proper, formed instead by runoff during a permafrost period that followed lake drawdown. Because both deltas are tied to ice-contact ridges that mark the former position of the retreating ice margin within the lake, luminescence ages we obtained for one of the deltas constrain the timing of ice retreat in this portion of Michigan, for which no information currently exists. Six OSL ages were obtained on the deltaic sands, recovered from 2 m deep soils pits on one of the deltas. These dates help to constrain the retreat of the subaqueously grounded ice margin through this region, which is thought to have been glaciated later (27 ka) than other parts of Michigan or the upper midwest.

DOI: 10.1130/abs/2016NC-274950

2016078146 Brinker, R. (Twelve Bridges Middle School, Science, Placerville, CA); Steiner, S. M. and Coleman, Lucy. From the field to the classroom; connecting climate research to classroom lessons [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract ED13B-0891, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Improving scientific literacy is a goal in the United States. Scientists from the United States are often expected to present research findings in ways that are meaningful and accessible to the general public, including K-12 students. PolarTREC - Teachers and Researchers Exploring and Collaborating, a program funded by the National Science Foundation, partners teachers with scientists in the Arctic and Antarctica. Teachers communicate the research to general audiences on a regular basis. After the field experience, they then create classroom-ready lessons to relay the science exploration into science curriculum. In this presentation, secondary level educators, will share their experiences with being part of field research teams in the Arctic and Antarctica, and their strategies for bringing current science research into the classroom and aligning lessons with Next Generation Science Standards (NGSS). Topics include an overview on using polar science to teach about climate change, application of field research techniques to improve students' understanding of scientific investigation methodology, phenology observations, soil porosity and permeability, litter decomposition, effect of sunlight on release of carbon dioxide from thawing permafrost, and understanding early life on Earth by studying stromatolites in Antarctica.

2016075266 Eisner, Wendy R. (University of Cincinnati, Cincinnati, OH); Hinkel, Kenneth M. and Cuomo, C. Twelve years of interviews with the Inupiat people of Arctic Alaska; report from a community workshop [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract ED43D-0886, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

On 20 August 2015, a workshop was held in Barrow, Alaska, which presented the highlights of 12 years of research connecting local indigenous knowledge of landscape processes with scientific research on arctic lakes, tundra changes, and permafrost stability. Seventy-six Inupiat elders, hunters, and other knowledge-holders from the North Slope villages of Barrow, Atqasuk, Wainwright, Nuiqsut, and Anaktuvuk Pass were interviewed, and over 75 hours of videotaped interviews were produced. The interviews provided information and observations on landforms, lakes, erosion, permafrost degradation and thermokarst, changes in the environment and in animal behavior, human modification of lakes, tundra damage from 4-wheel off-road vehicles, tundra trail expansion, and other phenomena. Community concerns regarding the impact of environmental change on food procurement, animal migration, human travel routes, and the future of subsistence practices were also prominent themes. Following an interview, each videotaped session was logged. Each time an elder pointed to a location on a map and explained a landscape event/observation or told a story, the time-stamp in the video was recorded. Each logged event consisted of a code and a short account of the observation. From these reference sheets, a Geographic Information System (GIS) dataset was created. A logged account for each videotape, with geographic coordinates, event code, and event description is available for each videotape. The goal of the workshop was to report on our findings, thank the community for their support, and collaboratively develop plans for archiving and disseminating this data. A complete video library and searchable, printed and digital issues of the logging dataset for archiving in the communities were also produced. Discussions with administrative personnel at the Tuzzy Library in Barrow and the Inupiat Heritage Center have enabled us to set standards and develop a timeline for turning over the library of videos and GIS data to the North Slope community.

2016074037 Gooseff, Michael N. (Institute of Arctic and Alpine Research, Boulder, CO); Adams, Byron; Barrett, John E.; Doran, Peter T.; Fountain, Andrew G.; Lyons, William B.; McKnight, Diane M.; Takacs-Vesbach, Cristina D.; Priscu, John C.; Sokol, Eric; Virginia, Ross A. and Wall, Diana H. The past as a window to the future; what does long term research in the McMurdo Dry Valleys, Antarctica tell us about the trajectory of polar ecosystems? [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC11G-1107, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The McMurdo Dry Valleys of Antarctica represent the largest ice-free area of the continent. The landscape is dominated by glaciers, exposed soils, streams, and ice-covered lakes, and hosts an incredible ecosystem that is largely driven by microbes and some invertebrates. Given the low air temperatures (-18C annual mean), little precipitation (<10 cm water equivalent/yr), and lack of vegetation cover, the Dry Valleys ecosystem is strongly influenced by physical processes. In the past two decades, summer conditions have been observed to fluctuate significantly. From 1986-2001, the area experienced a cooling trend and the ecosystem responded with decreasing soil invertebrate populations, decreased streamflow, decreased primary productivity in lakes, and decreased algal biomass in streams. Since 2001, 3 very high glacial melt years have occurred producing record stream flows and extensive wetted soils. During this most recent decade, the levels of closed-basin lakes have risen substantially, with increasing heat contents, and we have observed increased permafrost degradation along streambanks. Here we assess the ecosystem responses of the cooling 'press' that occurred from 1986-2001 and the more most recent decade that has had several strong pulses of energy driving the system to develop expectations for the future state and function of this polar desert ecosystem. We propose that the future trajectory of climate and energy input to the region will likely be more inconsistent than the cooling period was. Hence, the ecosystem will be consistently responding to pulses of change over varying time periods. We also expect that recovery of the ozone layer over Antarctica may play an important role in modifying both regional climate and the Dry Valleys ecosystem.

2016075695 Harms, Tamara (University of Alaska Fairbanks, Fairbanks, AK). Biogeochemical responses of Arctic hillslopes to storms and seasonal thaw [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract H12D-08, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Resilience of watersheds includes maintenance of biogeochemical functions, including retention and transport of solutes, following perturbations. In the arctic, important perturbations that may result in departure from the current state of watersheds include gradual or catastrophic loss of permafrost, increasing temperature, and increased intensity of storms. However, these long-term changes are occurring against the backdrop of variation introduced by seasonality and storms. Thus, establishing baselines that capture temporal patterns is an essential step in predicting vulnerability of arctic watersheds to climate-induced change. We have documented temporal patterns in solute concentrations of six water tracks, zero-order channels that drain arctic hillslopes. Temporal patterns were typically site-specific, underscoring the value of watershed monitoring for predicting responses to perturbations. In some catchments, peak export of organic carbon, nitrogen, and phosphorus occurred during snowmelt, whereas in others, flushing during storms yielded greater export. Concentrations of non-limiting inorganic solutes (e.g., sulfate, calcium) increased through the thaw period in some catchments, suggesting that these solutes may serve as indicators of degrading permafrost. We observed a decrease in the magnitude of flushing of biolabile solutes (e.g., ammonium, organic carbon) during storms through the thaw season, reflecting hydrologic disconnection of upper, organic soils as thaw depth increases and flowpaths deepen. The observed patterns establish a template of temporal variation against which future observations may be assessed to evaluate departures from a stable state.

2016074038 Jensen, Anne M. (University of Alaska Fairbanks, Anthropology, Fairbanks, AK). Distributed observing networks of the past; using archaeological sites to study global change [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC11G-1108, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The Arctic is changing rapidly, and there is much concern over what the effects of those changes might be. Although changes of considerable magnitude have happened in the past, current understanding of Arctic systems is not yet sufficient to enable useful predictions. Scientific observations span a very limited period in the Arctic, and do not encompass even fairly recent (Little Ice Age, Medieval Climate Anomaly) periods of climate change. One way to address this would be to extend the period of observation, but the situation is urgent. As an alternative, various types of proxy data can serve a similar function. It is suggested that archaeological sites with good organic preservation are not only sources of data on past human behavior and cultural organization, but also valuable resources for paleoenvironmental reconstruction, with potential similar to other paleoenvironmental proxy records. The sites tend to be located at or near places that are still occupied today, thus providing locally relevant data. They also tend to incorporate the same range of species that are important for subsistence and food security today, so that one can examine how changes affected those species in the past in a fairly direct manner. Yet, just as new methods increase our ability to retrieve and study this information, global climate change poses a dire threat, both to the wealth of organic data in such sites, and to many of the sites themselves. Global change-related threats including increased coastal erosion and the warming and thawing of permafrost are major and imminent threats to the archaeological and paleoecological record.

2016074060 Shakhova, Natalia E. (University of Alaska Fairbanks, Fairbanks, AK). Methane emissions in the East Siberian Arctic Shelf; issues addressed and questions raised [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC14C-06, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Methane (CH₄) emissions in the East Siberian Arctic Shelf (ESAS) has been studied during the last decade. Our investigation, including observational studies using hydrological, biogeochemical, geophysical, geo-electrical, microbiological, and isotopic methods, and modeling efforts to assess current subsea permafrost state and the ESAS' contribution to the regional CH₄ budget, have clarified processes driving CH₄ emissions in the ESAS and spilt some light on possible sources involvement. Despite some authors believe that CH₄ fluxes from subsea permafrost in the ESAS will depend on rates of CH₄ production in gradually thawing sediments while subsea permafrost will remain frozen for millennia, results of our investigation showed the opposite. Permafrost failure caused by long-lasting warming by sea water due to sea level rise, deep/open taliks formation due to combined heating effects of seawater, river runoff, geothermal flux, and pre-existing thermokarst and global-change-induced warming, determines destabilization of massive gas reservoirs, leading to large-scale CH₄ releases, including release of pre-formed CH₄ long preserved within/beneath subsea permafrost. Resultant rates of CH₄ emissions over the ESAS vary spatially by 3-5 orders of magnitude. Re-drilling of subsea permafrost performed from the fast ice 30 years after it was first drilled in 1982-1983, revealed modern rates of subsea permafrost degradation. These results contradict previous hypotheses that: 1) taliks beneath thermokarst lakes always freeze after submergence; 2) rates of permafrost degradation after inundation decrease over time; and 3) thousands of years required to form escape paths for permafrost-preserved gas. Involvement of shallow relic hydrates is suggested based on results of experimental work with sediment cores extracted from the near-shore zone of the ESAS. In-situ investigations revealed that dissolved CH₄ could remain in the seawater up to 1000 days, because oxidation rates are low. Storms could release some aqueous CH₄ to atmosphere; dissolved CH₄, captured beneath ice in winter, can spread via currents and escape to atmosphere through breaks in the ice. Progressive subsea permafrost thawing and decreasing ice extent could significantly increase CH₄ emissions from the ESAS.

2016075673 Shum, C. K. (Ohio State University, Division of Geodetic Science, Columbus, OH); Su, Xiaoli; Shang, Kun; Cogley, J. Graham; Zhang Guoqing; Howat, Ian M.; Braun, Alexander and Kuo, Chung-Yen. Asia high mountain glacier mass balance [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract G53A-01, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The Asian High Mountain encompassing the Qinghai-Tibetan Plateau has the largest glaciated regions in the world outside of Greenland and Antarctica. The Tibetan Plateau is the source or headwater of many major river systems, which provide water resources to more than a billion people downstream. The impact of climate change on the Tibetan Plateau physical processes, including mountain glacier wastage, permafrost active layer thickening, the timing and the quantity of the perennial snowpack melt affecting upstream catchments, river runoffs, land-use, have significant effects on downstream water resources. Exact quantification of the Asian High Mountain glacier wastage or its mass balance on how much of the melt water contributes to early 21st century global sea-level rise, remain illusive or the published results are arguably controversial. The recent observed significant increase of freshwater storage within the Tibetan Plateaus remains a limitation to exactly quantify mountain glacier wastage. Here, we provide an updated estimate of Asia high mountain glacier mass balance using satellite geodetic observations during the last decade, accounting for the hydrologic and other processes, and validated against available in situ mass balance data.

2016074112 Turetsky, Merritt R. (University of Guelph, Guelph, ON, Canada). The burning of surface and deep peat during boreal forest and peatland fires; implications for fire behaviour and global carbon cycling [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC42B-03, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Fire is increasingly appreciated as a threat to peatlands and their carbon stocks. The global peatland carbon pool exceeds that of global vegetation and is similar to the current atmospheric carbon pool. Under pristine conditions, most of the peat carbon stock is protected from burning, and resistance to fire has increased peat carbon storage in high latitude regions over long time scales. This, in part, is due to the high porosity and storage coefficient of surface peat, which minimizes water table variability and maintains wet conditions even during drought. However, higher levels of disturbance associated with warming and increasing human activities are triggering state changes and the loss of resiliency in some peatland systems. This presentation will summarize information on burn area and severity in peatlands under undisturbed scenarios of hydrologic self-regulation, and will assess the consequences of warming and drying on peatland vegetation and wildfire behaviour. Our goal is to predict where and when peatlands will become more vulnerable to deep smouldering, given the importance of deep peat layers to global carbon cycling, permafrost stability, and a variety of other ecosystem services in northern regions. Results from two major wildfire seasons (2004 in Alaska and 2014 in the Northwest Territories) show that biomass burning in peatlands releases similar amounts of carbon to the atmosphere as patterns of burning in upland forests, but that peatlands are less vulnerable to severe burning that tends to occur in boreal forests during late season fire activity.

2016074073 Yu, Qin (George Washington University, Geography, Washington, DC); Shiklomanov, Nikolay I.; Streletskiy, Dmitry A.; Engstrom, Ryan and Epstein, Howard E. Detecting anthropogenic and climate change induced land cover and land use change in the vicinity of an oil/gas facility in northwestern Siberia, Russia [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC33F-04, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Arctic ecosystems are changing dramatically due to changes in climate, vegetation and human activities. Northwestern Siberia is one of the regions which has been undergoing various land cover and land use changes associated primarily with animal husbandry and oil/gas development. These changes have been exacerbated by warming climatic conditions over the last fifty years. In this study, we investigated land cover and land use changes associated with oil and gas development southeast of the city of Nadym within the context of climate change based on multi-source and multi-temporal remote sensing imagery. The impacts of land use on surface vegetation, radiation, and hydrological properties were evaluated using the Normalized Difference Vegetation Index (NDVI), albedo and the Normalized Difference Water Index (NDWI). The results from a comparison between high spatial resolution imagery acquired in 1968 and 2006 indicate that the vegetation cover was reduced in areas disturbed by oil and gas development. Vegetation cover increased in natural landscapes over the same period,. Water logging was found along the linear structures near the oil/gas development, while in natural landscapes the drying of thermokarst lakes is evident due to permafrost degradation. Derived indices suggest that the direct impacts associated with infrastructure development are mostly within 100 m distance from the disturbance source. While these impacts are rather localized they persist for decades despite partial recovery of vegetation after the initial disturbance.

2016079779 Mann, Paul J. (Northumbria University, Newcastle Upon Tyne, United Kingdom); Vonk, Jorien E.; McIntyre, Cameron; Eglinton, Timothy I.; Holmes, Robert M.; Stubbins, Aron and Spencer, Robert G. M. Biogeochemical processes in Arctic rivers and the land-ocean interface [abstr.]: in Goldschmidt abstracts 2015, V.M. Goldschmidt Conference - Program and Abstracts, 25, p. 1995, 2015. Meeting: Goldschmidt 2015, Aug. 16-21, 2015, Prague, Czech Republic.

URL: http://goldschmidt.info/2015/uploads/abstracts/finalPDFs/1995.pdf

2016079809 Martin, Ellen E. (University of Florida, Department of Geological Sciences, Gainesville, FL); Scribner, Cecilia A.; Martin, Jonathan B. and Deuerling, Kelly M. Weathering in deglaciated watersheds of western Greenland [abstr.]: in Goldschmidt abstracts 2015, V.M. Goldschmidt Conference - Program and Abstracts, 25, p. 2025, 2015. Meeting: Goldschmidt 2015, Aug. 16-21, 2015, Prague, Czech Republic.

URL: http://goldschmidt.info/2015/uploads/abstracts/finalPDFs/2025.pdf

2016075980 Wang Shuyun (Chinese Academy of Sciences, Institute of Mechanics, Beijing, China); Zhang Xuhui; Lu Xiaobing and Nie Xuyuan. Laboratory study on physical and mechanical properties of hydrate sediment samples: in Proceeding of the Twenty-fourth (2014) international ocean and polar engineering conference (Chung, Jin S., editor; et al.), The Proceedings of the ... International Offshore and Polar Engineering Conference, 24, Volume 1, p. 40-43, 2014. Meeting: Twenty-fourth international ocean and polar engineering conference, June 15-20, 2014, Busan, South Korea. Based on Publisher-supplied data.

2016081128 Kerr, Phillip J. (Iowa Geological Survey, Iowa City, IA); Streeter, Matthew T.; Tassier-Surine, Stepanie; Clark, Ryan J. and Liu, Huaibao P. Surficial geology of the New Haven, Iowa 7.5' quadrangle [abstr.]: in Geological Society of America, North-Central Section, 50th annual meeting, Abstracts with Programs - Geological Society of America, 48(5), Abstract no. 27-2, 2016. Meeting: Geological Society of America, North-Central Section, 50th annual meeting, April 18-19, 2016, Champaign, IL.

The New Haven Quadrangle is located in Mitchell County in north-central Iowa. The quadrangle is located on the Wisconsin-age Iowan Surface Landform Region. A period of intense cold occurred during the Wisconsin full glacial episode from 21,000 to 16,500 years before present. This cold episode and ensuing upland erosion led to the development of the distinctive landform recognized as the Iowan Surface. A periglacial environment prevailed during this period with intensive freeze-thaw action, solifluction, strong winds, and a host of other periglacial processes. The data collected to interpret this mapping area was comprised of well cutting samples stored in the repository of the Iowa Geological Survey, field observations, and core samples. This was combined with existing soil surveys, LiDAR, and existing geologic maps. The map area is dominated by unnamed erosion surface sediments of variable thickness overlying Wisconsin-age Sheldon Creek Formation glacial sediments, Pre-Illinoian glacial sediments, or shallow rock. Quaternary deposits in this quadrangle generally vary in thickness from 0 to 14 m (1 to 45 ft), but there are several bedrock valleys with the largest being up to 83 m (275 ft) below the surface on the eastern edge of the quadrangle. Results from this mapping program and others in Worth and Cerro Gordo counties to the west indicate that Sheldon Creek glacial materials extend much farther east than previously thought. Mapping that will be completed in 2016 of the entirety of Mitchell County should help resolve that boundary.

DOI: 10.1130/abs/2016NC-275125

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2016080088 Stevens, C. W.; Kerr, D. E.; Wolfe, S. A. and Eagles, S. Predictive surficial geology, Yellowknife and Hearne Lake, Northwest Territories, NTS 85-J and NTS 85-I: Geological Survey of Canada, Canadian Geoscience Map, Geological Survey of Canada, Ottawa, ON, Canada, Rep. No. 200, 1 sheet (French sum.), illus. incl. color surficial geology map, 1:125,000, 3 ref., 2015. ISBN: 978-1-100-24852-3. Preliminary edition.

This predictive surficial geology map is derived from integrating digital datasets of satellite imagery and interpreted air photos. The limit of airphoto interpretation defines training areas where surficial geology map units and landforms have been identified, and used in the generation of the predictive map. Some additional geological features in these areas include small bedrock outcrops, kames, thermokarst depressions, patterned ground, beach ridges, and escarpments. These features may also exist beyond the boundaries of the airphoto interpreted areas. Lakes may include hydrographic layers and mask areas.

DOI: 10.4095/295700

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