WorldWideScience

Sample records for surface permafrost degradation

  1. Review: Impacts of permafrost degradation on inorganic chemistry of surface fresh water

    Science.gov (United States)

    Colombo, Nicola; Salerno, Franco; Gruber, Stephan; Freppaz, Michele; Williams, Mark; Fratianni, Simona; Giardino, Marco

    2018-03-01

    Recent studies have shown that climate change is impacting the inorganic chemical characteristics of surface fresh water in permafrost areas and affecting aquatic ecosystems. Concentrations of major ions (e.g., Ca2 +, Mg2 +, SO42 -, NO3-) can increase following permafrost degradation with associated deepening of flow pathways and increased contributions of deep groundwater. In addition, thickening of the active layer and melting of near-surface ground ice can influence inorganic chemical fluxes from permafrost into surface water. Permafrost degradation has also the capability to modify trace element (e.g., Ni, Mn, Al, Hg, Pb) contents in surface water. Although several local and regional modifications of inorganic chemistry of surface fresh water have been attributed to permafrost degradation, a comprehensive review of the observed changes is lacking. The goal of this paper is to distil insight gained across differing permafrost settings through the identification of common patterns in previous studies, at global scale. In this review we focus on three typical permafrost configurations (pervasive permafrost degradation, thermokarst, and thawing rock glaciers) as examples and distinguish impacts on (i) major ions and (ii) trace elements. Consequences of warming climate have caused spatially-distributed progressive increases of major ion and trace element delivery to surface fresh water in both polar and mountain areas following pervasive permafrost degradation. Moreover, localised releases of major ions and trace elements to surface water due to the liberation of soluble materials sequestered in permafrost and ground ice have been found in ice-rich terrains both at high latitude (thermokarst features) and high elevation (rock glaciers). Further release of solutes and related transport to surface fresh water can be expected under warming climatic conditions. However, complex interactions among several factors able to influence the timing and magnitude of the impacts

  2. Might short term rockglacier surface morphological changes be attributed to permafrost degradation ?

    Science.gov (United States)

    Perrier, Romain; Cossart, Etienne; Fort, Monique

    2015-04-01

    In high mountain environments, permafrost is increasingly affected by climate change. Rockglaciers represent the expression of creeping permafrost: they are generally considered as good geo-indicators of cryosphere distribution and evolution. Research dealing with the effect of climate change on rockglacier degradation is mostly based on photogrammetric studies as well as geophysics. Major results on rockglaciers behavior in relation to increasing mean annual air temperature are summarized as follows. Firstly, photogrammetry analysis shows that rockglacier surface velocities are higher when the permafrost temperature and/or water content increase within the rockglacier system; this can sometimes lead to the destabilization/collapse of rockglaciers. Secondly, geophysical studies demonstrate a decrease in resistivities within the rockglacier body in relation to a decrease in ice content hence suggesting a degradation of permafrost. Although these methods are appropriate for studying the effects of climate change on mountain permafrost and rockglacier evolution, their application is fairly costly and time-consuming, and are usually restricted to one or two study cases. Our investigations over a wider area up to regional scale require completing our approach by using surface morphological changes, a method that can identify potential degradation in a warming context. In this context, this work intends to characterize short terms (multi-decades) surface morphological changes at rockglacier scale and to determine if these changes may be attributed to potential permafrost degradation. Our investigations have been carried out in both Clarée and Ubaye valleys, in the French Southern Alps. Here we present our results obtained from the Lac Rouge rockglacier (45°02'49''N, 6°30'16''E; 2600-2825m a.s.l, Clarée valley, French Southern Alps). Analysis of multi-temporal aerial photographs, geomorphological field mapping, electrical resistivity tomographies and surface

  3. Sensitivity of a model projection of near-surface permafrost degradation to soil column depth and representation of soil organic matter.

    Science.gov (United States)

    David M. Lawrence; Andrew G. Slater; Vladimir E. Romanovsky; Dmitry J. Nicolsky

    2008-01-01

    The sensitivity of a global land-surface model projection of near-surface permafrost degradation is assessed with respect to explicit accounting of the thermal and hydrologic properties of soil organic matter and to a deepening of the soil column from 3.5 to 50 or more m. Together these modifications result in substantial improvements in the simulation of near-surface...

  4. Evidence for nonuniform permafrost degradation after fire in boreal landscapes

    Science.gov (United States)

    Minsley, Burke J.; Pastick, Neal J.; Wylie, Bruce K.; Brown, Dana R.N.; Kass, M. Andy

    2016-01-01

    Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. We present a combination of multiscale remote sensing, geophysical, and field observations that reveal details of both near-surface (1 m) impacts of fire on permafrost. Along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska, subsurface electrical resistivity and nuclear magnetic resonance data indicate locations where permafrost appears to be resilient to disturbance from fire, areas where warm permafrost conditions exist that may be most vulnerable to future change, and also areas where permafrost has thawed. High-resolution geophysical data corroborate remote sensing interpretations of near-surface permafrost and also add new high-fidelity details of spatial heterogeneity that extend from the shallow subsurface to depths of about 10 m. Results show that postfire impacts on permafrost can be variable and depend on multiple factors such as fire severity, soil texture, soil moisture, and time since fire.

  5. Permafrost Degradation Risk Zone Assessment using Simulation Models

    DEFF Research Database (Denmark)

    Daanen, R.P.; Ingeman-Nielsen, Thomas; Marchenko, S.

    2011-01-01

    as the potential active layer increase due to climate warming and surface alterations. PTP is then used in a simple risk assessment procedure useful for engineering applications. The modelling shows that climate warming will result in continuing wide-spread permafrost warming and degradation in Greenland......In this proof-of-concept study we focus on linking large scale climate and permafrost simulations to small scale engineering projects by bridging the gap between climate and permafrost sciences on the one hand and on the other technical recommendation for adaptation of planned infrastructures...

  6. Permafrost degradation in West Greenland

    DEFF Research Database (Denmark)

    Foged, Niels Nielsen; Ingeman-Nielsen, Thomas

    2012-01-01

    Important aspects of civil engineering in West Greenland relate to the presence of permafrost and mapping of the annual and future changes in the active layer due to the ongoing climatically changes in the Arctic. The Arctic Technology Centre (ARTEK) has worked more than 10 years on this topic...... parameters. It is planned as decision and planning tool for town planners and engineers in local municipality governments and to consulting engineers and contractors in Greenland, which also may be used in other arctic regions. Risk is classified in four categories: Low, Limited, Medium and High based...

  7. Degradation potentials of dissolved organic carbon (DOC) from thawed permafrost peat

    Science.gov (United States)

    Panneer Selvam, Balathandayuthabani; Lapierre, Jean-François; Guillemette, Francois; Voigt, Carolina; Lamprecht, Richard E.; Biasi, Christina; Christensen, Torben R.; Martikainen, Pertti J.; Berggren, Martin

    2017-04-01

    Global warming can substantially affect the export of dissolved organic carbon (DOC) from peat-permafrost to aquatic systems. The direct degradability of such peat-derived DOC, however, is poorly constrained because previous permafrost thaw studies have mainly addressed mineral soil catchments or DOC pools that have already been processed in surface waters. We incubated peat cores from a palsa mire to compare an active layer and an experimentally thawed permafrost layer with regard to DOC composition and degradation potentials of pore water DOC. Our results show that DOC from the thawed permafrost layer had high initial degradation potentials compared with DOC from the active layer. In fact, the DOC that showed the highest bio- and photo-degradability, respectively, originated in the thawed permafrost layer. Our study sheds new light on the DOC composition of peat-permafrost directly upon thaw and suggests that past estimates of carbon-dioxide emissions from thawed peat permafrost may be biased as they have overlooked the initial mineralization potential of the exported DOC.

  8. Assessing and Projecting Greenhouse Gas Release due to Abrupt Permafrost Degradation

    Science.gov (United States)

    Saito, K.; Ohno, H.; Yokohata, T.; Iwahana, G.; Machiya, H.

    2017-12-01

    Permafrost is a large reservoir of frozen soil organic carbon (SOC; about half of all the terrestrial storage). Therefore, its degradation (i.e., thawing) under global warming may lead to a substantial amount of additional greenhouse gas (GHG) release. However, understanding of the processes, geographical distribution of such hazards, and implementation of the relevant processes in the advanced climate models are insufficient yet so that variations in permafrost remains one of the large source of uncertainty in climatic and biogeochemical assessment and projections. Thermokarst, induced by melting of ground ice in ice-rich permafrost, leads to dynamic surface subsidence up to 60 m, which further affects local and regional societies and eco-systems in the Arctic. It can also accelerate a large-scale warming process through a positive feedback between released GHGs (especially methane), atmospheric warming and permafrost degradation. This three-year research project (2-1605, Environment Research and Technology Development Fund of the Ministry of the Environment, Japan) aims to assess and project the impacts of GHG release through dynamic permafrost degradation through in-situ and remote (e.g., satellite and airborn) observations, lab analysis of sampled ice and soil cores, and numerical modeling, by demonstrating the vulnerability distribution and relative impacts between large-scale degradation and such dynamic degradation. Our preliminary laboratory analysis of ice and soil cores sampled in 2016 at the Alaskan and Siberian sites largely underlain by ice-rich permafrost, shows that, although gas volumes trapped in unit mass are more or less homogenous among sites both for ice and soil cores, large variations are found in the methane concentration in the trapped gases, ranging from a few ppm (similar to that of the atmosphere) to hundreds of thousands ppm We will also present our numerical approach to evaluate relative impacts of GHGs released through dynamic

  9. Tracking permafrost soil degradation through sulphur biogeochemical tracers

    Science.gov (United States)

    Canario, João; Santos, Margarida C.; Vieira, Gonçalo; Vincent, Warwick F.

    2017-04-01

    Rising temperatures are contributing to the rapid degradation of Arctic permafrost soils. Several studies have been using some biogeochemical tracers as indicators of the organic matter degradation although fewer attention has been given to sulphur. In fact, the chemistry of this element is of environmental importance because it plays a key role in the degradation of natural organic matter and influences the partitioning, speciation and fate of other trace elements. To better understand the role of sulphur in biogeochemical processes in permafrost soils several campaigns were undertaken in the Canadian subarctic region of Kuujjuarapik-Whapmagoostui and Umiujaq (QC) as a part of the Canadian ADAPT and the Portuguese PERMACHEM projects. In four sites along those regions soil samples were collected and pore water were extracted. Dissolved sulphur compounds (sulphide and sulphate) were determined in water samples while in soils particulate sulphides, pyrite and elemental sulphur were quantified by voltammetry. Organic sulphur compounds were identified using 33SssNMR and X-ray diffraction both in powder and single crystal analysis were used to identify crystalline sulphides. Finally, subsamples of soils and water samples were analysed for total particulate and dissolved organic carbon. The results showed that sulphur composition depends largely on the origin of permafrost soils. In soils originated from organic-rich palsas, the proportion of organic sulphur (% of the total) is higher than 50%, while in mineral lithalsa soils the opposite was found. In both cases the origin of sulphur was mainly from plant organic matter degradation. The combined structural and chemical analysis allowed the identified different stages of soil degradation by determined the ratio between inorganic and organic sulphur species and by following the different NMR and XRD spectra. These preliminary results pointed to the importance of the sulphur biogeochemistry in permafrost soils and provide

  10. Reorganization of vegetation, hydrology and soil carbon after permafrost degradation across heterogeneous boreal landscapes

    Science.gov (United States)

    Jorgenson, M. Torre; Harden, Jennifer; Kanevskiy, Mikhail; O'Donnell, Jonathan; Wickland, Kim; Ewing, Stephanie; Manies, Kristen; Zhuang, Qianlai; Shur, Yuri; Striegl, Robert G.; Koch, Josh

    2013-01-01

    The diversity of ecosystems across boreal landscapes, successional changes after disturbance and complicated permafrost histories, present enormous challenges for assessing how vegetation, water and soil carbon may respond to climate change in boreal regions. To address this complexity, we used a chronosequence approach to assess changes in vegetation composition, water storage and soil organic carbon (SOC) stocks along successional gradients within four landscapes: (1) rocky uplands on ice-poor hillside colluvium, (2) silty uplands on extremely ice-rich loess, (3) gravelly–sandy lowlands on ice-poor eolian sand and (4) peaty–silty lowlands on thick ice-rich peat deposits over reworked lowland loess. In rocky uplands, after fire permafrost thawed rapidly due to low ice contents, soils became well drained and SOC stocks decreased slightly. In silty uplands, after fire permafrost persisted, soils remained saturated and SOC decreased slightly. In gravelly–sandy lowlands where permafrost persisted in drier forest soils, loss of deeper permafrost around lakes has allowed recent widespread drainage of lakes that has exposed limnic material with high SOC to aerobic decomposition. In peaty–silty lowlands, 2–4 m of thaw settlement led to fragmented drainage patterns in isolated thermokarst bogs and flooding of soils, and surface soils accumulated new bog peat. We were not able to detect SOC changes in deeper soils, however, due to high variability. Complicated soil stratigraphy revealed that permafrost has repeatedly aggraded and degraded in all landscapes during the Holocene, although in silty uplands only the upper permafrost was affected. Overall, permafrost thaw has led to the reorganization of vegetation, water storage and flow paths, and patterns of SOC accumulation. However, changes have occurred over different timescales among landscapes: over decades in rocky uplands and gravelly–sandy lowlands in response to fire and lake drainage, over decades to

  11. Climate warming over the past half century has led to thermal degradation of permafrost on the Qinghai-Tibet Plateau

    Science.gov (United States)

    Ran, Youhua; Li, Xin; Cheng, Guodong

    2018-02-01

    Air temperature increases thermally degrade permafrost, which has widespread impacts on engineering design, resource development, and environmental protection in cold regions. This study evaluates the potential thermal degradation of permafrost over the Qinghai-Tibet Plateau (QTP) from the 1960s to the 2000s using estimated decadal mean annual air temperatures (MAATs) by integrating remote-sensing-based estimates of mean annual land surface temperatures (MASTs), leaf area index (LAI) and fractional snow cover values, and decadal mean MAAT date from 152 weather stations with a geographically weighted regression (GWR). The results reflect a continuous rise of approximately 0.04 °C a-1 in the decadal mean MAAT values over the past half century. A thermal-condition classification matrix is used to convert modelled MAATs to permafrost thermal type. Results show that the climate warming has led to a thermal degradation of permafrost in the past half century. The total area of thermally degraded permafrost is approximately 153.76 × 104 km2, which corresponds to 88 % of the permafrost area in the 1960s. The thermal condition of 75.2 % of the very cold permafrost, 89.6 % of the cold permafrost, 90.3 % of the cool permafrost, 92.3 % of the warm permafrost, and 32.8 % of the very warm permafrost has been degraded to lower levels of thermal condition. Approximately 49.4 % of the very warm permafrost and 96 % of the likely thawing permafrost has degraded to seasonally frozen ground. The mean elevations of the very cold, cold, cool, warm, very warm, and likely thawing permafrost areas increased by 88, 97, 155, 185, 161, and 250 m, respectively. The degradation mainly occurred from the 1960s to the 1970s and from the 1990s to the 2000s. This degradation may lead to increased risks to infrastructure, reductions in ecosystem resilience, increased flood risks, and positive climate feedback effects. It therefore affects the well-being of millions of people

  12. Distribution of near-surface permafrost in Alaska: estimates of present and future conditions

    Science.gov (United States)

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Nield, Shawn J.; Johnson, Kristofer D.; Finley, Andrew O.

    2015-01-01

    High-latitude regions are experiencing rapid and extensive changes in ecosystem composition and function as the result of increases in average air temperature. Increasing air temperatures have led to widespread thawing and degradation of permafrost, which in turn has affected ecosystems, socioeconomics, and the carbon cycle of high latitudes. Here we overcome complex interactions among surface and subsurface conditions to map nearsurface permafrost through decision and regression tree approaches that statistically and spatially extend field observations using remotely sensed imagery, climatic data, and thematic maps of a wide range of surface and subsurface biophysical characteristics. The data fusion approach generated medium-resolution (30-m pixels) maps of near-surface (within 1 m) permafrost, active-layer thickness, and associated uncertainty estimates throughout mainland Alaska. Our calibrated models (overall test accuracy of ~85%) were used to quantify changes in permafrost distribution under varying future climate scenarios assuming no other changes in biophysical factors. Models indicate that near-surface permafrost underlies 38% of mainland Alaska and that near-surface permafrost will disappear on 16 to 24% of the landscape by the end of the 21st Century. Simulations suggest that near-surface permafrost degradation is more probable in central regions of Alaska than more northerly regions. Taken together, these results have obvious implications for potential remobilization of frozen soil carbon pools under warmer temperatures. Additionally, warmer and drier conditions may increase fire activity and severity, which may exacerbate rates of permafrost thaw and carbon remobilization relative to climate alone. The mapping of permafrost distribution across Alaska is important for land-use planning, environmental assessments, and a wide-array of geophysical studies.

  13. Survey of Permafrost Thaw Influence on Surface Water Dissolved Organic Matter in Sub-Arctic Alaska

    Science.gov (United States)

    Gagne, K.; Walter Anthony, K. M.; Guerard, J.

    2016-12-01

    The chemical and functional group composition of permafrost organic matter largely remains unknown. Characterizing dissolved organic matter (DOM) chemical composition offers insight into the quality and extent of the permafrost carbon pool that may mobilize and transform into smaller components or greenhouse gasses upon thaw. The Goldstream watershed in interior Alaska is underlain by discontinuous permafrost with varying stage of talik (thaw bulb) development, allowing for the comparison of thaw stage on DOM composition. Surface water samples were collected from lakes and streams in regions of the watershed with varying degrees of permafrost thaw in order to investigate seasonal variability and associated trends in DOM composition. Additionally, select permafrost cores were obtained and utilized in leachate experiments to identify the fraction and reactivity of the soil organic carbon pool leached from active layer and permafrost soil upon thaw. Leached organic moieties were compared to the total permafrost organic carbon pool and the DOM of the overlying surface water. Extracted isolates from both permafrost and active layer were characterized by 3D excitation-emission fluorescence, UV-vis spectroscopy, PARAFAC, SPR-W5-WATERGATE 1H- NMR, total organic carbon, ICP-MS, and ion chromatography, coupled with photolysis experiments to determine reactive oxygen species production to characterize potential reactivity. Differences in carbon pool composition were resolved between seasons and with the extent of permafrost thaw. This is a key first step to determine how permafrost degradation influences DOM pool composition on a molecular level, which is essential for assessing permafrost organic matter impact on biogeochemical cycling and other ecological functions as it becomes incorporated into a warming landscape.

  14. Surface and subsurface conditions in permafrost areas - a literature review

    International Nuclear Information System (INIS)

    Vidstrand, Patrik

    2003-02-01

    This report contains a summary of some of the information within existing technical and scientific literature on permafrost. Permafrost is viewed as one of the future climate driven process domains that may exist in Scandinavia, and that may give rise to significantly different surface and subsurface conditions than the present. Except for changes in the biosphere, permafrost may impact hydraulic, mechanical, and chemical subsurface processes and conditions. Permafrost and its influences on the subsurface conditions are thus of interest for the performance and safety assessments of deep geological waste repositories. The definition of permafrost is 'ground that stays at or below 0 deg C for at least two consecutive years'. Permafrost will effect the geological subsurface to some depth. How deep the permafrost may grow is a function of the heat balance, thermal conditions at the surface and within the ground, and the geothermal heat flux from the Earth's inner parts. The main chapters of the report summaries the knowledge on permafrost evolution, occurrence and distribution, and extracts information concerning hydrology and mechanical and chemical impacts due to permafrost related conditions. The results of a literature review are always dependent on the available literature. Concerning permafrost there is some literature available from investigations in the field of long-term repositories and some from mining industries. However, reports of these investigations are few and the bulk of permafrost literature comes from the science departments concerned with surficial processes (e.g. geomorphology, hydrology, agriculture, etc) and from engineering concerns, such as foundation of constructions and pipeline design. This focus within the permafrost research inevitably yields a biased but also an abundant amount of information on localised surficial processes and a limited amount on regional and deep permafrost characteristics. Possible conclusions are that there is

  15. Surface and subsurface conditions in permafrost areas - a literature review

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik [Bergab, Goeteborg (Sweden)

    2003-02-01

    This report contains a summary of some of the information within existing technical and scientific literature on permafrost. Permafrost is viewed as one of the future climate driven process domains that may exist in Scandinavia, and that may give rise to significantly different surface and subsurface conditions than the present. Except for changes in the biosphere, permafrost may impact hydraulic, mechanical, and chemical subsurface processes and conditions. Permafrost and its influences on the subsurface conditions are thus of interest for the performance and safety assessments of deep geological waste repositories. The definition of permafrost is 'ground that stays at or below 0 deg C for at least two consecutive years'. Permafrost will effect the geological subsurface to some depth. How deep the permafrost may grow is a function of the heat balance, thermal conditions at the surface and within the ground, and the geothermal heat flux from the Earth's inner parts. The main chapters of the report summaries the knowledge on permafrost evolution, occurrence and distribution, and extracts information concerning hydrology and mechanical and chemical impacts due to permafrost related conditions. The results of a literature review are always dependent on the available literature. Concerning permafrost there is some literature available from investigations in the field of long-term repositories and some from mining industries. However, reports of these investigations are few and the bulk of permafrost literature comes from the science departments concerned with surficial processes (e.g. geomorphology, hydrology, agriculture, etc) and from engineering concerns, such as foundation of constructions and pipeline design. This focus within the permafrost research inevitably yields a biased but also an abundant amount of information on localised surficial processes and a limited amount on regional and deep permafrost characteristics. Possible conclusions are that

  16. Reorganization of vegetation, hydrology and soil carbon after permafrost degradation across heterogeneous boreal landscapes

    International Nuclear Information System (INIS)

    Torre Jorgenson, M; Harden, Jennifer; Manies, Kristen; Kanevskiy, Mikhail; Shur, Yuri; O’Donnell, Jonathan; Wickland, Kim; Striegl, Robert; Ewing, Stephanie; Zhuang Qianlai; Koch, Josh

    2013-01-01

    The diversity of ecosystems across boreal landscapes, successional changes after disturbance and complicated permafrost histories, present enormous challenges for assessing how vegetation, water and soil carbon may respond to climate change in boreal regions. To address this complexity, we used a chronosequence approach to assess changes in vegetation composition, water storage and soil organic carbon (SOC) stocks along successional gradients within four landscapes: (1) rocky uplands on ice-poor hillside colluvium, (2) silty uplands on extremely ice-rich loess, (3) gravelly–sandy lowlands on ice-poor eolian sand and (4) peaty–silty lowlands on thick ice-rich peat deposits over reworked lowland loess. In rocky uplands, after fire permafrost thawed rapidly due to low ice contents, soils became well drained and SOC stocks decreased slightly. In silty uplands, after fire permafrost persisted, soils remained saturated and SOC decreased slightly. In gravelly–sandy lowlands where permafrost persisted in drier forest soils, loss of deeper permafrost around lakes has allowed recent widespread drainage of lakes that has exposed limnic material with high SOC to aerobic decomposition. In peaty–silty lowlands, 2–4 m of thaw settlement led to fragmented drainage patterns in isolated thermokarst bogs and flooding of soils, and surface soils accumulated new bog peat. We were not able to detect SOC changes in deeper soils, however, due to high variability. Complicated soil stratigraphy revealed that permafrost has repeatedly aggraded and degraded in all landscapes during the Holocene, although in silty uplands only the upper permafrost was affected. Overall, permafrost thaw has led to the reorganization of vegetation, water storage and flow paths, and patterns of SOC accumulation. However, changes have occurred over different timescales among landscapes: over decades in rocky uplands and gravelly–sandy lowlands in response to fire and lake drainage, over decades to

  17. Effects of permafrost degradation on alpine grassland in a semi-arid basin on the Qinghai–Tibetan Plateau

    International Nuclear Information System (INIS)

    Yi Shuhua; Zhou Zhaoye; Ren Shilong; Xu Ming; Qin Yu; Chen Shengyun; Ye Baisheng

    2011-01-01

    Permafrost on the Qinghai–Tibetan Plateau (QTP) has degraded over the last few decades. Its ecological effects have attracted great concern. Previous studies focused mostly at plot scale, and hypothesized that degradation of permafrost would cause lowering of the water table and drying of shallow soil and then degradation of alpine grassland. However, none has been done to test the hypothesis at basin scale. In this study, for the first time, we investigated the relationships between land surface temperature (LST) and fractional vegetation cover (FVC) in different types of permafrost zone to infer the limiting condition (water or energy) of grassland growth on the source region of Shule River Basin, which is located in the north-eastern edge of the QTP. LST was obtained from MODIS Aqua products at 1 km resolution, while FVC was upscaled from quadrat (50 cm) to the same resolution as LST, using 30 m resolution NDVI data of the Chinese HJ satellite. FVC at quadrat scale was estimated by analyzing pictures taken with a multi-spectral camera. Results showed that (1) retrieval of FVC at quadrat scale using a multi-spectral camera was both more accurate and more efficient than conventional methods and (2) the limiting factor of vegetation growth transitioned from energy in the extreme stable permafrost zone to water in the seasonal frost zone. Our study suggested that alpine grassland would respond differently to permafrost degradation in different types of permafrost zone. Future studies should consider overall effects of permafrost degradation, and avoid the shortcomings of existing studies, which focus too much on the adverse effects.

  18. Permafrost degradation stimulates carbon loss from experimentally warmed tundra.

    Science.gov (United States)

    Natali, Susan M; Schuur, Edward A G; Webb, Elizabeth E; Pries, Caitlin E Hicks; Crummer, Kathryn G

    2014-03-01

    A large pool of organic carbon (C) has been accumulating in the Arctic for thousands of years because cold and waterlogged conditions have protected soil organic material from microbial decomposition. As the climate warms this vast and frozen C pool is at risk of being thawed, decomposed, and released to the atmosphere as greenhouse gasses. At the same time, some C losses may be offset by warming-mediated increases in plant productivity. Plant and microbial responses to warming ultimately determine net C exchange from ecosystems, but the timing and magnitude of these responses remain uncertain. Here we show that experimental warming and permafrost (ground that remains below 0 degrees C for two or more consecutive years) degradation led to a two-fold increase in net ecosystem C uptake during the growing season. However, warming also enhanced winter respiration, which entirely offset growing-season C gains. Winter C losses may be even higher in response to actual climate warming than to our experimental manipulations, and, in that scenario, could be expected to more than double overall net C losses from tundra to the atmosphere. Our results highlight the importance of winter processes in determining whether tundra acts as a C source or sink, and demonstrate the potential magnitude of C release from the permafrost zone that might be expected in a warmer climate.

  19. Controls on the methane released through ebullition affected by permafrost degradation

    Science.gov (United States)

    S.J. Klapstein; M.R. Turetsky; A.D. McGuire; J.W. Harden; C.I. Czimczik; X. Xu; J.P. Chanton; J.M. Waddington

    2014-01-01

    Permafrost thaw in peat plateaus leads to the flooding of surface soils and the formation of collapse scar bogs, which have the potential to be large emitters of methane (CH4) from surface peat as well as deeper, previously frozen, permafrost carbon (C). We used a network of bubble traps, permanently installed 20 cm and 60 cm beneath the moss surface, to examine...

  20. Quantifying Permafrost Extent, Condition, and Degradation at Department of Defense Installations in the Arctic

    Science.gov (United States)

    Edlund, C. A.

    2017-12-01

    The Department of Defense (DoD) is planning over $500M in military construction on Eielson Air Force Base (AFB) within the next three fiscal years. This construction program will expand the footprint of facilities and change the storm water management scheme, which will have second order effects on the underlying permafrost layer. These changes in permafrost will drive engineering decision making at local and regional levels, and help shape the overall strategy for military readiness in the Arctic. Although many studies have attempted to predict climate change induced permafrost degradation, very little site-specific knowledge exists on the anthropogenic effects to permafrost at this location. In 2016, the permafrost degradation rates at Eielson AFB were modeled using the Geophysics Institute Permafrost Laboratory (GIPL) 2.1 model and limited available geotechnical and climate data. Model results indicated a degradation of the discontinuous permafrost layer at Eielson AFB of up to 7 meters in depth over the next century. To further refine an understanding of the geophysics at Eielson AFB and help engineers and commanders make more informed decisions on engineering and operations in the arctic, this project established two permafrost monitoring stations near the future construction sites. Installation of the stations occurred in July 2017. Permafrost was located and characterized using two Electrical Resistivity Tomography surveys, as well as direct frost probe measurements. Using this data, the research team optimized the placement location and depth of two long term ground temperature monitoring stations, and then installed the stations for data collection. The data set generated by these stations are the first of their kind at Eielson AFB, and represent the first systematic effort in the DoD to quantify permafrost condition before, during, and after construction and other anthropogenic activities in order to fully understand the effects of that activity in the

  1. Modeling near-shore subsea permafrost degradation in the Laptev Sea

    Science.gov (United States)

    Kneier, F.; Langer, M.; Overduin, P. P.

    2012-12-01

    Most subsea permafrost in the Arctic Ocean shelf regions is relict terrestrial permafrost that was inundated by sea water by rising sea levels after the last glacial period. Permafrost usually degrades offshore under the influence of sea-bottom temperatures, salt infiltration and a wide range of near-shore coastal processes. Subsea permafrost instability has important potential implications due to the release of methane to the atmosphere and by increasing coastal erosion rates. Our objectives are to employ meso-scale numerical calculations (from meter to kilometer, 1000s of years) in connection with borehole data from the Laptev Sea to model the transition of permafrost from onshore to offshore conditions. The goal is to identify key processes driving permafrost degradation in the near-shore zone of the shelf. The heat transfer equation is solved numerically taking into account freeze-thaw processes in a three-phase heat capacity / conductivity model. Sediment composition and initial temperature profiles are derived from field and laboratory analysis of the borehole data. Our approach neglects some processes such as solute diffusion, but includes the effect of pore water salinity on phase state and thermal properties. Measured temperature profiles are compared to the modeled subsea soil temperature evolution over the course of the 2500 year transgression of the farthest offshore borehole in the transect. The degradation of the ice-bearing permafrost table or thaw depth is of special interest due to its direct relation to sediment stability and as the most readily discernible feature in the field observations. Temperature profiles generally agree well with model calculations reproducing the almost isothermal permafrost profiles currently observed, but show more variation potentially partially caused by drilling disturbances. The thaw depth is mainly driven by salt contamination and infiltration into deeper pore water with time. Complicating near-shore processes

  2. Diminishing friction of joint surfaces as initiating factor for destabilising permafrost rocks?

    Science.gov (United States)

    Funk, Daniel; Krautblatter, Michael

    2010-05-01

    Degrading alpine permafrost due to changing climate conditions causes instabilities in steep rock slopes. Due to a lack in process understanding, the hazard is still difficult to asses in terms of its timing, location, magnitude and frequency. Current research is focused on ice within joints which is considered to be the key-factor. Monitoring of permafrost-induced rock failure comprises monitoring of temperature and moisture in rock-joints. The effect of low temperatures on the strength of intact rock and its mechanical relevance for shear strength has not been considered yet. But this effect is signifcant since compressive and tensile strength is reduced by up to 50% and more when rock thaws (Mellor, 1973). We hypotheisze, that the thawing of permafrost in rocks reduces the shear strength of joints by facilitating the shearing/damaging of asperities due to the drop of the compressive/tensile strength of rock. We think, that decreasing surface friction, a neglected factor in stability analysis, is crucial for the onset of destabilisation of permafrost rocks. A potential rock slide within the permafrost zone in the Wetterstein Mountains (Zugspitze, Germany) is the basis for the data we use for the empirical joint model of Barton (1973) to estimate the peak shear strength of the shear plane. Parameters are the JRC (joint roughness coefficient), the JCS (joint compressive strength) and the residual friction angle (φr). The surface roughness is measured in the field with a profile gauge to create 2D-profiles of joint surfaces. Samples of rock were taken to the laboratory to measure compressive strength using a high-impact Schmidt-Hammer under air-dry, saturated and frozen conditions on weathered and unweathered surfaces. Plugs where cut out of the rock and sand blasted for shear tests under frozen and unfrozen conditions. Peak shear strength of frozen and unfrozen rocks will be calculated using Barton's model. First results show a mean decrease of compressive

  3. Degrading Discontinuous Permafrost Detected by Repeated Electrical Resistivity Tomography Surveys, Northwest Canada

    Science.gov (United States)

    Lewkowicz, A.; Holloway, J.

    2016-12-01

    Climate change is causing permafrost to warm rapidly in most of the Arctic. In subarctic regions where permafrost is discontinuous, however, rates of frozen ground warming are slower. This is because net positive heat fluxes at the surface of the ground and geothermal heat are transformed into latent heat associated with increases in soil unfrozen moisture content, especially in fine-grained soils at temperatures just below 0°C. At such sites, monitoring of temperatures in boreholes may be insufficient to track progressive change both because thaw may occur laterally, and because the slow alteration of temperature may be less than the accuracy of the instrumentation. Electrical Resistivity Tomography (ERT) surveys represent an alternative technique to monitor permafrost change because the electrical properties of soils alter significantly as their unfrozen moisture contents increase. We present results from multi-year studies in Yukon, northern British Columbia and the Northwest Territories where repeated ERT surveys using permanent or temporary electrode arrays reveal progressive thaw of thin permafrost at undisturbed sites in the boreal forest, and at sites affected by recent forest fire or changes in surface drainage. These field observations not only show the impact of climate and surface change on permafrost, they also demonstrate the efficacy of ERT as a means of monitoring sites where frost tables are too deep to be probed or where taliks have developed. We conclude that ERT surveys should be incorporated into international monitoring networks such as the Global Terrestrial Network for Permafrost since they can reveal progressive change at sites where ground temperatures, in contrast, suggest stable permafrost conditions.

  4. Resolution capacity of geophysical monitoring regarding permafrost degradation induced by hydrological processes

    Directory of Open Access Journals (Sweden)

    B. Mewes

    2017-12-01

    Full Text Available Geophysical methods are often used to characterize and monitor the subsurface composition of permafrost. The resolution capacity of standard methods, i.e. electrical resistivity tomography and refraction seismic tomography, depends not only on static parameters such as measurement geometry, but also on the temporal variability in the contrast of the geophysical target variables (electrical resistivity and P-wave velocity. Our study analyses the resolution capacity of electrical resistivity tomography and refraction seismic tomography for typical processes in the context of permafrost degradation using synthetic and field data sets of mountain permafrost terrain. In addition, we tested the resolution capacity of a petrophysically based quantitative combination of both methods, the so-called 4-phase model, and through this analysed the expected changes in water and ice content upon permafrost thaw. The results from the synthetic data experiments suggest a higher sensitivity regarding an increase in water content compared to a decrease in ice content. A potentially larger uncertainty originates from the individual geophysical methods than from the combined evaluation with the 4-phase model. In the latter, a loss of ground ice can be detected quite reliably, whereas artefacts occur in the case of increased horizontal or vertical water flow. Analysis of field data from a well-investigated rock glacier in the Swiss Alps successfully visualized the seasonal ice loss in summer and the complex spatially variable ice, water and air content changes in an interannual comparison.

  5. Response characteristics of vegetation and soil environment to permafrost degradation in the upstream regions of the Shule River Basin

    International Nuclear Information System (INIS)

    Chen Shengyun; Liu Wenjie; Qin Xiang; Liu Yushuo; Ren Jiawen; Qin Dahe; Zhang Tongzuo; Hu Fengzu; Chen Kelong

    2012-01-01

    Permafrost degradation exhibits striking and profound influences on the alpine ecosystem, and response characteristics of vegetation and soil environment to such degradation inevitably differ during the entire degraded periods. However, up to now, the related research is lacking in the Qinghai–Tibetan Plateau (QTP). For this reason, twenty ecological plots in the different types of permafrost zones were selected in the upstream regions of the Shule River Basin on the northeastern margin of the QTP. Vegetation characteristics (species diversity, community coverage and biomass etc) and topsoil environment (temperature (ST), water content (SW), mechanical composition (SMC), culturable microorganism (SCM), organic carbon (SOC) and total nitrogen (TN) contents and so on), as well as active layer thickness (ALT) were investigated in late July 2009 and 2010. A spatial–temporal shifts method (the spatial pattern that is represented by different types of permafrost shifting to the temporal series that stands for different stages of permafrost degradation) has been used to discuss response characteristics of vegetation and topsoil environment throughout the entire permafrost degradation. The results showed that (1) ST of 0–40 cm depth and ALT gradually increased from highly stable and stable permafrost (H-SP) to unstable permafrost (UP). SW increased initially and then decreased, and SOC content and the quantities of SCM at a depth of 0–20 cm first decreased and then increased, whereas TN content and SMC showed obscure trends throughout the stages of permafrost degradation with a stability decline from H-SP to extremely unstable permafrost (EUP); (2) further, species diversity, community coverage and biomass first increased and then decreased in the stages from H-SP to EUP; (3) in the alpine meadow ecosystem, SOC and TN contents increased initially and then decreased, soil sandy fractions gradually increased with stages of permafrost degradation from substable (SSP

  6. Responses of alpine grassland on Qinghai–Tibetan plateau to climate warming and permafrost degradation: a modeling perspective

    International Nuclear Information System (INIS)

    Yi, Shuhua; Wang, Xiaoyun; Qin, Yu; Ding, Yongjian; Xiang, Bo

    2014-01-01

    Permafrost plays a critical role in soil hydrology. Thus, the degradation of permafrost under warming climate conditions may affect the alpine grassland ecosystem on the Qinghai–Tibetan Plateau. Previous space-for-time studies using plot and basin scales have reached contradictory conclusions. In this study, we applied a process-based ecosystem model (DOS-TEM) with a state-of-the-art permafrost hydrology scheme to examine this issue. Our results showed that 1) the DOS-TEM model could properly simulate the responses of soil thermal and hydrological dynamics and of ecosystem dynamics to climate warming and spatial differences in precipitation; 2) the simulated results were consistent with plot-scale studies showing that warming caused an increase in maximum unfrozen thickness, a reduction in vegetation and soil carbon pools as a whole, and decreases in soil water content, net primary production, and heterotrophic respiration; and 3) the simulated results were also consistent with basin-scale studies showing that the ecosystem responses to warming were different in regions with different combinations of water and energy constraints. Permafrost prevents water from draining into water reservoirs. However, the degradation of permafrost in response to warming is a long-term process that also enhances evapotranspiration. Thus, the degradation of the alpine grassland ecosystem on the Qinghai–Tibetan Plateau (releasing carbon) cannot be mainly attributed to the disappearing waterproofing function of permafrost. (letter)

  7. Thermokarst Associations with Landscape Characteristics in Arctic Alaska: Implications for Future Permafrost Degradation at Landscape to Regional Scales

    Science.gov (United States)

    Balser, A.; Jones, J. B.; Jorgenson, T.

    2010-12-01

    Permafrost degradation affects Arctic landscapes, and is controlled by myriad landscape characteristics. Thermokarst features can develop by catastrophic failure, gradual subsidence, or continual mass wasting and can be classified into discernible modes based upon mechanism, morphology and substrate characteristics. Relationships among landscape characteristics and several different modes of thermokarst provided strong predictors of regional scale thermokarst distribution. In the Brooks Range foothills of northern Alaska, several distinct modes of thermokarst predominated. Active-layer detachment slides were associated with 4-7° slopes, non-carbonate parent lithologies (particularly micaceous shale), ice-rich upper permafrost with >40 % segregation ice in a 20 cm horizon directly beneath the active layer, and non-tussock vegetation. Glacial thermokarst (including the central kettle lake and surrounding retrogressive thaw slumps), was confined to valley bottoms where glacial recession has deposited stagnate glacial ice typically insulated by ablation till, colluvial blankets, and peat. Thermo-erosional gullies occurred in landscapes that have substantial massive ice (typically wedges, although less commonly abundant segregated ice) and sustained surface water flow. Retrogressive thaw slumps not associated with buried glacial ice formed on 6-12° slopes with ice-rich permafrost containing >35 % visible segregated ice. These slumps occurred either on low hillslope positions along convex bluffs, or as secondary features extending uphill from pre-existing active-layer detachment slides. Observations indicate that thermokarst formation has three essential components: (1) sufficient volume of ground ice of varying morphologies; (2) a set of distinctive landscape conditions (e.g. surficial materials, slopes and gravitational energy, vegetation, and water flow); and (3) a triggering mechanism caused by unusual weather or a disturbance event, although glacial thermokarst

  8. Permafrost Meta-Omics and Climate Change

    Science.gov (United States)

    Mackelprang, Rachel; Saleska, Scott R.; Jacobsen, Carsten Suhr; Jansson, Janet K.; Taş, Neslihan

    2016-06-01

    Permanently frozen soil, or permafrost, covers a large portion of the Earth's terrestrial surface and represents a unique environment for cold-adapted microorganisms. As permafrost thaws, previously protected organic matter becomes available for microbial degradation. Microbes that decompose soil carbon produce carbon dioxide and other greenhouse gases, contributing substantially to climate change. Next-generation sequencing and other -omics technologies offer opportunities to discover the mechanisms by which microbial communities regulate the loss of carbon and the emission of greenhouse gases from thawing permafrost regions. Analysis of nucleic acids and proteins taken directly from permafrost-associated soils has provided new insights into microbial communities and their functions in Arctic environments that are increasingly impacted by climate change. In this article we review current information from various molecular -omics studies on permafrost microbial ecology and explore the relevance of these insights to our current understanding of the dynamics of permafrost loss due to climate change.

  9. a Research on Monitoring Surface Deformation and Relationships with Surface Parameters in Qinghai Tibetan Plateau Permafrost

    Science.gov (United States)

    Mi, S. J.; Li, Y. T.; Wang, F.; Li, L.; Ge, Y.; Luo, L.; Zhang, C. L.; Chen, J. B.

    2017-09-01

    The Qinghai Tibetan Plateau permafrost has been the largest permafrost region in middle-low latitude in the world for its high altitude. For the large area permafrost, especially surface deformation brought by it, have serious influence on the road engineering, road maintaining and regional economic development. Consequently, it is essential to monitor the surface deformation and study factors that influent it. We monitored an area named Wudaoliang from July 25, 2015 to June 1, 2016 and 15 Sentinel images were obtained during this time. The area we chose is about 35 kilometers long and 2 kilometers wide, and the national road 109 of China passes through the area. The traditional PS-INSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) method is not suitable because less historical images in the research area and leading to the number of PS (Persistent Scatterer) points is not enough to obtain accurate deformation results. Therefore, in this paper, we used another method which named QUASI-PSInSAR (QUASI Persistent Scatterer Interferometric Synthetic Aperture Radar) to acquire deformation for it has the advantage to weaken or eliminate the effects of spatial and temporal correlation, which has proved by other scholar. After processing 15 images in the SARproz software, we got the conclusions that, 1) the biggest deformation velocity in the whole area was about 127.9mm/year and about 109.3 mm/year in the road; 2) apparent deformation which have surface deformation more than 30mm/year was about 1.7Km in the road. Meanwhile, soil moisture(SM), Land surface temperature (LST) and surface water(SW), which are primary parameters of the land surface over the same time were reversed by using Sentinel data, Landsat data and ZY-3 data, respectively. After analyzing SM, LST , SW and deformation, we obtained that wet areas which had bigger SM, lower LST and more SW, had greater percentage of severe deformation than arid areas; besides, deformation pattern were

  10. Surface geophysical methods for characterising frozen ground in transitional permafrost landscapes

    Science.gov (United States)

    Briggs, Martin A.; Campbell, Seth; Nolan, Jay; Walvoord, Michelle Ann; Ntarlagiannis, Dimitrios; Day-Lewis, Frederick D.; Lane, John W.

    2017-01-01

    The distribution of shallow frozen ground is paramount to research in cold regions, and is subject to temporal and spatial changes influenced by climate, landscape disturbance and ecosystem succession. Remote sensing from airborne and satellite platforms is increasing our understanding of landscape-scale permafrost distribution, but typically lacks the resolution to characterise finer-scale processes and phenomena, which are better captured by integrated surface geophysical methods. Here, we demonstrate the use of electrical resistivity imaging (ERI), electromagnetic induction (EMI), ground penetrating radar (GPR) and infrared imaging over multiple summer field seasons around the highly dynamic Twelvemile Lake, Yukon Flats, central Alaska, USA. Twelvemile Lake has generally receded in the past 30 yr, allowing permafrost aggradation in the receded margins, resulting in a mosaic of transient frozen ground adjacent to thick, older permafrost outside the original lakebed. ERI and EMI best evaluated the thickness of shallow, thin permafrost aggradation, which was not clear from frost probing or GPR surveys. GPR most precisely estimated the depth of the active layer, which forward electrical resistivity modelling indicated to be a difficult target for electrical methods, but could be more tractable in time-lapse mode. Infrared imaging of freshly dug soil pit walls captured active-layer thermal gradients at unprecedented resolution, which may be useful in calibrating emerging numerical models. GPR and EMI were able to cover landscape scales (several kilometres) efficiently, and new analysis software showcased here yields calibrated EMI data that reveal the complicated distribution of shallow permafrost in a transitional landscape.

  11. Prokaryotic communities and operating metabolisms in the surface and the permafrost of Deception Island (Antarctica)

    NARCIS (Netherlands)

    Blanco, Yolanda; Prieto-Ballesteros, Olga; Gómez, Manuel J.; Moreno-Paz, Mercedes; García-Villadangos, Miriam; Rodríguez-Manfredi, José Antonio; Cruz-Gil, Patricia; Sánchez-Román, Mónica; Rivas, Luis A.; Parro, Victor

    In this study we examined the microbial community composition and operating metabolisms on the surface and in the permafrost of Deception Island, (Antarctica) with an on site antibody microarray biosensor. Samples (down to a depth of 4.2m) were analysed with LDChip300 (Life Detector Chip), an

  12. Extreme fire events are related to previous-year surface moisture conditions in permafrost-underlain larch forests of Siberia

    International Nuclear Information System (INIS)

    Forkel, Matthias; Beer, Christian; Thonicke, Kirsten; Cramer, Wolfgang; Bartalev, Sergey; Schmullius, Christiane

    2012-01-01

    Wildfires are a natural and important element in the functioning of boreal forests. However, in some years, fires with extreme spread and severity occur. Such severe fires can degrade the forest, affect human values, emit huge amounts of carbon and aerosols and alter the land surface albedo. Usually, wind, slope and dry air conditions have been recognized as factors determining fire spread. Here we identify surface moisture as an additional important driving factor for the evolution of extreme fire events in the Baikal region. An area of 127 000 km 2 burned in this region in 2003, a large part of it in regions underlain by permafrost. Analyses of satellite data for 2002–2009 indicate that previous-summer surface moisture is a better predictor for burned area than precipitation anomalies or fire weather indices for larch forests with continuous permafrost. Our analysis advances the understanding of complex interactions between the atmosphere, vegetation and soil, and how coupled mechanisms can lead to extreme events. These findings emphasize the importance of a mechanistic coupling of soil thermodynamics, hydrology, vegetation functioning, and fire activity in Earth system models for projecting climate change impacts over the next century. (letter)

  13. Increasing risks related to landslides from degrading permafrost into new lakes in de-glaciating mountain ranges

    Science.gov (United States)

    Haeberli, Wilfried; Schaub, Yvonne; Huggel, Christian

    2017-09-01

    While glacier volumes in most cold mountain ranges rapidly decrease due to continued global warming, degradation of permafrost at altitudes above and below glaciers is much slower. As a consequence, many still existing glacier and permafrost landscapes probably transform within decades into new landscapes of bare bedrock, loose debris, sparse vegetation, numerous new lakes and steep slopes with slowly degrading permafrost. These new landscapes are likely to persist for centuries if not millennia to come. During variable but mostly extended future time periods, such new landscapes will be characterized by pronounced disequilibria within their geo- and ecosystems. This especially involves long-term stability reduction of steep/icy mountain slopes as a slow and delayed reaction to stress redistribution following de-buttressing by vanishing glaciers and to changes in mechanical strength and hydraulic permeability caused by permafrost degradation. Thereby, the probability of far-reaching flood waves from large mass movements into lakes systematically increases with the formation of many new lakes and systems of lakes in close neighborhood to, or even directly at the foot of, so-affected slopes. Results of recent studies in the Swiss Alps are reviewed and complemented with examples from the Cordillera Blanca in Peru and the Mount Everest region in Nepal. Hot spots of future hazards from potential flood waves caused by large rock falls into new lakes can already now be recognized. To this end, integrated spatial information on glacier/permafrost evolution and lake formation can be used together with scenario-based models for rapid mass movements, impact waves and flood propagation. The resulting information must then be combined with exposure and vulnerability considerations related to settlements and infrastructure. This enables timely planning of risk reduction options. Such risk reduction options consist of two components: Mitigation of hazards, which in the present

  14. Decadal changes of surface elevation over permafrost area estimated using reflected GPS signals

    Science.gov (United States)

    Liu, Lin; Larson, Kristine M.

    2018-02-01

    Conventional benchmark-based survey and Global Positioning System (GPS) have been used to measure surface elevation changes over permafrost areas, usually once or a few times a year. Here we use reflected GPS signals to measure temporal changes of ground surface elevation due to dynamics of the active layer and near-surface permafrost. Applying the GPS interferometric reflectometry technique to the multipath signal-to-noise ratio data collected by a continuously operating GPS receiver mounted deep in permafrost in Barrow, Alaska, we can retrieve the vertical distance between the antenna and reflecting surface. Using this unique kind of observables, we obtain daily changes of surface elevation during July and August from 2004 to 2015. Our results show distinct temporal variations at three timescales: regular thaw settlement within each summer, strong interannual variability that is characterized by a sub-decadal subsidence trend followed by a brief uplift trend, and a secular subsidence trend of 0.26 ± 0.02 cm year-1 during 2004 and 2015. This method provides a new way to fully utilize data from continuously operating GPS sites in cold regions for studying dynamics of the frozen ground consistently and sustainably over a long time.

  15. Permafrost degradation and associated ground settlement estimation under 2 °C global warming

    Science.gov (United States)

    Guo, Donglin; Wang, Huijun

    2017-10-01

    Global warming of 2 °C above preindustrial levels has been considered to be the threshold that should not be exceeded by the global mean temperature to avoid dangerous interference with the climate system. However, this global mean target has different implications for different regions owing to the globally nonuniform climate change characteristics. Permafrost is sensitive to climate change; moreover, it is widely distributed in high-latitude and high-altitude regions where the greatest warming is predicted. Permafrost is expected to be severely affected by even the 2 °C global warming, which, in turn, affects other systems such as water resources, ecosystems, and infrastructures. Using air and soil temperature data from ten coupled model intercomparison project phase five models combined with observations of frozen ground, we investigated the permafrost thaw and associated ground settlement under 2 °C global warming. Results show that the climate models produced an ensemble mean permafrost area of 14.01 × 106 km2, which compares reasonably with the area of 13.89 × 106 km2 (north of 45°N) in the observations. The models predict that the soil temperature at 6 m depth will increase by 2.34-2.67 °C on area average relative to 1990-2000, and the increase intensifies with increasing latitude. The active layer thickness will also increase by 0.42-0.45 m, but dissimilar to soil temperature, the increase weakens with increasing latitude due to the distinctly cooler permafrost at higher latitudes. The permafrost extent will obviously retreat north and decrease by 24-26% and the ground settlement owing to permafrost thaw is estimated at 3.8-15 cm on area average. Possible uncertainties in this study may be mostly attributed to the less accurate ground ice content data and coarse horizontal resolution of the models.

  16. Permafrost Meta-Omics and Climate Change

    Energy Technology Data Exchange (ETDEWEB)

    Mackelprang, Rachel; Saleska, Scott R.; Jacobsen, Carsten Suhr; Jansson, Janet K.; Taş, Neslihan

    2016-06-29

    Permafrost (i.e., soil that has been frozen for at least 2 consecutive years) represents a habitat for microbial life at subzero temperatures (Gilichinsky et al. 2008). Approximately one quarter of the Earth’s surface is underlain by permafrost, which contains 25-50% of the total global soil carbon pool (Schuur et al. 2008, Tarnocai et al. 2009). This carbon is largely protected from microbial decomposition by reduced microbial activity in frozen conditions, but climate change is threatening to induce large-scale permafrost thaw thus exposing it to degradation. The resulting emissions of greenhouse gasses (GHGs) can produce a positive feedback loop and significantly amplify the effects of global warming. Increasing temperatures at high latitudes, changes in precipitation patterns, and frequent fire events have already initiated a widespread degradation of permafrost (Schuur et al. 2015).

  17. Sensitivity of airborne geophysical data to sublacustrine and near-surface permafrost thaw

    Science.gov (United States)

    Minsley, Burke J.; Wellman, Tristan; Walvoord, Michelle Ann; Revil, Andre

    2014-01-01

    A coupled hydrogeophysical forward and inverse modeling approach is developed to illustrate the ability of frequency-domain airborne electromagnetic (AEM) data to characterize subsurface physical properties associated with sublacustrine permafrost thaw during lake-talik formation. Numerical modeling scenarios are evaluated that consider non-isothermal hydrologic responses to variable forcing from different lake depths and for different hydrologic gradients. A novel physical property relationship connects the dynamic distribution of electrical resistivity to ice saturation and temperature outputs from the SUTRA groundwater simulator with freeze–thaw physics. The influence of lithology on electrical resistivity is controlled by a surface conduction term in the physical property relationship. Resistivity models, which reflect changes in subsurface conditions, are used as inputs to simulate AEM data in order to explore the sensitivity of geophysical observations to permafrost thaw. Simulations of sublacustrine talik formation over a 1000-year period are modeled after conditions found in the Yukon Flats, Alaska. Synthetic AEM data are analyzed with a Bayesian Markov chain Monte Carlo algorithm that quantifies geophysical parameter uncertainty and resolution. Major lithological and permafrost features are well resolved by AEM data in the examples considered. The subtle geometry of partial ice saturation beneath lakes during talik formation cannot be resolved using AEM data, but the gross characteristics of sub-lake resistivity models reflect bulk changes in ice content and can identify the presence of a talik. A final synthetic example compares AEM and ground-based electromagnetic responses for their ability to resolve shallow permafrost and thaw features in the upper 1–2 m below ground outside the lake margin.

  18. Tundra permafrost thaw causes significant shifts in energy partitioning

    Directory of Open Access Journals (Sweden)

    Christian Stiegler

    2016-04-01

    Full Text Available Permafrost, a key component of the arctic and global climate system, is highly sensitive to climate change. Observed and ongoing permafrost degradation influences arctic hydrology, ecology and biogeochemistry, and models predict that rapid warming is expected to significantly reduce near-surface permafrost and seasonally frozen ground during the 21st century. These changes raise concern of how permafrost thaw affects the exchange of water and energy with the atmosphere. However, associated impacts of permafrost thaw on the surface energy balance and possible feedbacks on the climate system are largely unknown. In this study, we show that in northern subarctic Sweden, permafrost thaw and related degradation of peat plateaus significantly change the surface energy balance of three peatland complexes by enhancing latent heat flux and, to less degree, also ground heat flux at the cost of sensible heat flux. This effect is valid at all radiation levels but more pronounced at higher radiation levels. The observed differences in flux partitioning mainly result from the strong coupling between soil moisture availability, vegetation composition, albedo and surface structure. Our results suggest that ongoing and predicted permafrost degradation in northern subarctic Sweden ultimately result in changes in land–atmosphere coupling due to changes in the partitioning between latent and sensible heat fluxes. This in turn has crucial implications for how predictive climate models for the Arctic are further developed.

  19. Acidification of the Shallow Arctic Seas as Biogeochemical Consequences of Permafrost Degradation

    Science.gov (United States)

    Semiletov, I. P.; Shakhova, N. E.; Pipko, I.; Repina, I.; Pugach, S.; Dudarev, O.; Charkin, A.

    2013-12-01

    There is increasing concern about consequences of ocean acidification from the increasing atmospheric carbon dioxide driven shifts toward lower seawater pH The largest pH changes in this century are anticipated in the surface waters of the Arctic ocean (Orr et al., 2005; Steinacher et al., 2009). Concurrently, aragonite undersaturation might occur locally and become widespread as atmospheric CO2 increases to more than 450ppm (Olafsson et al., 2009). However, the ocean acidification effects induced by increasing Arctic land-shelf export of fluvial and erosional organic carbon (OC) and its oxidation are unknown. Here we show that massive net redistribution of old OC from thawing permafrost to the East-Siberian Arctic Seas (ESAS) and its consequent remineralization drives acidification over the ESAS which represents the broadest and shallowest shelf of the World Ocean. From top to the bottom the ESAS waters were observed to be undersaturated with respect to aragonite and calcite, and thus potentially corrosive to CaCO3 for the shelf sediments and benthic ecosystems. Our multiyear all-seasonal results (1999-2011) demonstrate how the net ecosystem metabolism of the Siberian shelves, which is the net balance of autotrophic (photosynthesis and net community production) and heterotrophic (respiration and remineralization) processes, is likely to function as the heterotrophic dominated ecosystem. CO2 outgassing from the East Siberian Arctic Shelf (ESAS) is quantified using multi-year eddy-correlation flux measurements. It is shown that the ESAS is currently a source of atmospheric CO2. A continuing warming adds more terrestrial OC to the Arctic Shelf Seas, which increases pCO2, as the same time as decreased transparency lowers primary production, which reduce consumption of CO2 (and increase acidification effects). This effect results in a positive feedback by outgassing CO2 over the Siberian Shelf , which comprises one half of the entire shelf area. This multi-year study

  20. Assessment of climate and land use change impacts on surface water runoff and connectivity in a continuous permafrost catchment on the Arctic Coastal Plain, Alaska

    Science.gov (United States)

    Gaedeke, A.; Arp, C. D.; Liljedahl, A. K.; Daanen, R. P.; Whitman, M. S.

    2016-12-01

    A changing climate is leading to rapid transformations of hydrological processes in low-gradient Arctic terrestrial ecosystems which are dominated by lakes and ponds, wetlands, polygonised tundra, and connecting stream and river networks. The aim of this study is to gain a deeper understanding of the impacts of climate and land use change on surface water availability and connectivity by utilizing the process-based, spatially distributed hydrological model WaSiM. Crea Creek Watershed (30 km2), which is located in the National Petroleum Reserve-Alaska (NPR-A) was chosen as study area because of its permafrost landforms (bedfast and floating ice lakes, high and low centered polygons), existing observational data (discharge, snow depth, and meteorological variables since 2009), and resource management issues related to permafrost degradation and aquatic habitat dynamics. Foremost of concern is oil development scheduled to begin starting in 2017 with the construction of a permanent road and drilling pad directly within the Crea Watershed. An interdisciplinary team consisting of scientists and regional stakeholders defined the following scenarios to be simulated using WaSiM: (1) industrial development (impact of water removal from lakes (winter) for ice road construction on downstream (summer) runoff), (2) permanent road construction to allow oil companies access to develop and extract petroleum, and (3) potential modes of climate change including warmer, snowier winters and prolonged drought during summers. Downscaled meteorological output from the Weather Research & Forecasting Model (WRF) will be used as the forcing for analysis of climate scenarios alone and for assessment of land-use responses under varying climate scenarios. Our results will provide regional stakeholders with information on the impacts of climate and land use change on surface water connectivity that affects aquatic habitat, as well as lake hydrologic interactions with permafrost. These finding

  1. Permafrost and changing climate: the Russian perspective.

    Science.gov (United States)

    Anisimov, Oleg; Reneva, Svetlana

    2006-06-01

    The permafrost regions occupy about 25% of the Northern Hemisphere's terrestrial surface, and more than 60% of that of Russia. Warming, thawing, and degradation of permafrost have been observed in many locations in recent decades and are likely to accelerate in the future as a result of climatic change. Changes of permafrost have important implications for natural systems, humans, and the economy of the northern lands. Results from mathematical modeling indicate that by the mid-21st century, near-surface permafrost in the Northern Hemisphere may shrink by 15%-30%, leading to complete thawing of the frozen ground in the upper few meters, while elsewhere the depth of seasonal thawing may increase on average by 15%-25%, and by 50% or more in the northernmost locations. Such changes may shift the balance between the uptake and release of carbon in tundra and facilitate emission of greenhouse gases from the carbon-rich Arctic wetlands. Serious public concerns are associated with the effects that thawing permafrost may have on the infrastructure constructed on it. Climate-induced changes of permafrost properties are potentially detrimental to almost all structures in northern lands, and may render many of them unusable. Degradation of permafrost and ground settlement due to thermokarst may lead to dramatic distortions of terrain and to changes in hydrology and vegetation, and may lead ultimately to transformation of existing landforms. Recent studies indicate that nonclimatic factors, such as changes in vegetation and hydrology, may largely govern the response of permafrost to global warming. More studies are needed to better understand and quantify the effects of multiple factors in the changing northern environment.

  2. Monitoring Inter- and Intra-Seasonal Dynamics of Rapidly Degrading Ice-Rich Permafrost Riverbanks in the Lena Delta with TerraSAR-X Time Series

    Directory of Open Access Journals (Sweden)

    Samuel Stettner

    2017-12-01

    Full Text Available Arctic warming is leading to substantial changes to permafrost including rapid degradation of ice and ice-rich coasts and riverbanks. In this study, we present and evaluate a high spatiotemporal resolution three-year time series of X-Band microwave satellite data from the TerraSAR-X (TSX satellite to quantify cliff-top erosion (CTE of an ice-rich permafrost riverbank in the central Lena Delta. We apply a threshold on TSX backscatter images and automatically extract cliff-top lines to derive intra- and inter-annual CTE. In order to examine the drivers of erosion we statistically compare CTE with climatic baseline data using linear mixed models and analysis of variance (ANOVA. Our evaluation of TSX-derived CTE against annual optical-derived CTE and seasonal in situ measurements showed good agreement between all three datasets. We observed continuous erosion from June to September in 2014 and 2015 with no significant seasonality across the thawing season. We found the highest net annual cliff-top erosion of 6.9 m in 2014, in accordance with above-average mean temperatures and thawing degree days as well as low precipitation. We found high net annual erosion and erosion variability in 2015 associated with moderate mean temperatures but above average precipitation. According to linear mixed models, climate parameters alone could not explain intra-seasonal erosional patterns and additional factors such as ground ice content likely drive the observed erosion. Finally, mean backscatter intensity on the cliff surface decreased from −5.29 to −6.69 dB from 2013 to 2015, respectively, likely resulting from changes in surface geometry and properties that could be connected to partial slope stabilization. Overall, we conclude that X-Band backscatter time series can successfully be used to complement optical remote sensing and in situ monitoring of rapid tundra permafrost erosion at riverbanks and coasts by reliably providing information about intra

  3. On the Possibility of the Existence of a Surface Electromagnetic Wave in the Permafrost Area

    Science.gov (United States)

    Balkhanov, V. K.; Bashkuev, Yu. B.; Advokatov, V. R.

    2018-01-01

    The results of measurements of the vertical component of electric field at a radio path with the permafrost at a frequency of 255 kHz have been interpreted. An analysis of the results has shown that the considered radio path exhibits the properties of a two-part impedance surface, i.e., it consists of two sections. At a distance of 70 km from a radiation source and at a frequency of 255 kHz of the electromagnetic wave, the field decreases with the distance R according to the power law as R -1.5 and a power index takes an intermediate value between the power indices for decreasing the field in free space R -2 and for the decrease in the field above an ideal conducting surface R -1. With further propagation at a distance of 70-220 km, the field shows the specific behavior of a surface electromagnetic wave.

  4. Onset and stability of gas hydrates under permafrost in an environment of surface climatic change : past and future

    International Nuclear Information System (INIS)

    Majorowicz, J.A.; Osadetz, K.; Safanda, J.

    2008-01-01

    This paper presented a model designed to simulate permafrost and gas hydrate formation in a changing surface temperature environment in the Beaufort-Mackenzie Basin (BMB). The numerical model simulated surface forcing due to general cooling trends that began in the late Miocene era. This study modelled the onset of permafrost formation and subsequent gas hydrate formation in the changing surface temperature environment for the BMB. Paleoclimatic data were used. The 1-D model was constrained by deep heat flow from well bottom hole temperatures; conductivity; permafrost thickness; and the thickness of the gas hydrates. The model used latent heat effects for the ice-bearing permafrost and hydrate intervals. Surface temperatures for glacial and interglacial histories for the last 14 million years were considered. The model also used a detailed Holocene temperature history as well as a scenario in which atmospheric carbon dioxide (CO 2 ) levels were twice as high as current levels. Two scenarios were considered: (1) the formation of gas hydrates from gas entrapped under geological seals; and (2) the formation of gas hydrates from gas located in free pore spaces simultaneously with permafrost formation. Results of the study showed that gas hydrates may have formed at a depth of 0.9 km only 1 million years ago. Results of the other modelling scenarios suggested that the hydrates formed 6 million years ago, when temperature changes caused the gas hydrate layer to expand both downward and upward. Detailed models of more recent glacial and interglacial histories showed that the gas hydrate zones will persist under the thick body of the BMB permafrost through current interglacial warming as well as in scenarios where atmospheric CO 2 is doubled. 28 refs., 13 figs

  5. Modelling rock wall permafrost degradation in the Mont Blanc massif from the LIA to the end of the 21st century

    Science.gov (United States)

    Magnin, Florence; Josnin, Jean-Yves; Ravanel, Ludovic; Pergaud, Julien; Pohl, Benjamin; Deline, Philip

    2017-08-01

    High alpine rock wall permafrost is extremely sensitive to climate change. Its degradation has a strong impact on landscape evolution and can trigger rockfalls constituting an increasing threat to socio-economical activities of highly frequented areas; quantitative understanding of permafrost evolution is crucial for such communities. This study investigates the long-term evolution of permafrost in three vertical cross sections of rock wall sites between 3160 and 4300 m above sea level in the Mont Blanc massif, from the Little Ice Age (LIA) steady-state conditions to 2100. Simulations are forced with air temperature time series, including two contrasted air temperature scenarios for the 21st century representing possible lower and upper boundaries of future climate change according to the most recent models and climate change scenarios. The 2-D finite element model accounts for heat conduction and latent heat transfers, and the outputs for the current period (2010-2015) are evaluated against borehole temperature measurements and an electrical resistivity transect: permafrost conditions are remarkably well represented. Over the past two decades, permafrost has disappeared on faces with a southerly aspect up to 3300 m a.s.l. and possibly higher. Warm permafrost (i.e. > - 2 °C) has extended up to 3300 and 3850 m a.s.l. in N and S-exposed faces respectively. During the 21st century, warm permafrost is likely to extend at least up to 4300 m a.s.l. on S-exposed rock walls and up to 3850 m a.s.l. depth on the N-exposed faces. In the most pessimistic case, permafrost will disappear on the S-exposed rock walls at a depth of up to 4300 m a.s.l., whereas warm permafrost will extend at a depth of the N faces up to 3850 m a.s.l., but possibly disappearing at such elevation under the influence of a close S face. The results are site specific and extrapolation to other sites is limited by the imbrication of local topographical and transient effects.

  6. Evaluation of air-soil temperature relationships simulated by land surface models during winter across the permafrost region

    Science.gov (United States)

    Wang, Wenli; Rinke, Annette; Moore, John C.; Ji, Duoying; Cui, Xuefeng; Peng, Shushi; Lawrence, David M.; McGuire, A. David; Burke, Eleanor J.; Chen, Xiaodong; Delire, Christine; Koven, Charles; MacDougall, Andrew; Saito, Kazuyuki; Zhang, Wenxin; Alkama, Ramdane; Bohn, Theodore J.; Ciais, Philippe; Decharme, Bertrand; Gouttevin, Isabelle; Hajima, Tomohiro; Krinner, Gerhard; Lettenmaier, Dennis P.; Miller, Paul A.; Smith, Benjamin; Sueyoshi, Tetsuo

    2016-01-01

     A realistic simulation of snow cover and its thermal properties are important for accurate modelling of permafrost. We analyze simulated relationships between air and near-surface (20 cm) soil temperatures in the Northern Hemisphere permafrost region during winter, with a particular focus on snow insulation effects in nine land surface models and compare them with observations from 268 Russian stations. There are large across-model differences as expressed by simulated differences between near-surface soil and air temperatures, (ΔT), of 3 to 14 K, in the gradients between soil and air temperatures (0.13 to 0.96°C/°C), and in the relationship between ΔT and snow depth. The observed relationship between ΔT and snow depth can be used as a metric to evaluate the effects of each model's representation of snow insulation, and hence guide improvements to the model’s conceptual structure and process parameterizations. Models with better performance apply multi-layer snow schemes and consider complex snow processes. Some models show poor performance in representing snow insulation due to underestimation of snow depth and/or overestimation of snow conductivity. Generally, models identified as most acceptable with respect to snow insulation simulate reasonable areas of near-surface permafrost (12–16 million km2). However, there is not a simple relationship between the quality of the snow insulation in the acceptable models and the simulated area of Northern Hemisphere near-surface permafrost, likely because several other factors such as differences in the treatment of soil organic matter, soil hydrology, surface energy calculations, and vegetation also provide important controls on simulated permafrost distribution.

  7. Geophysical mapping of deep permafrost change after disturbance

    Science.gov (United States)

    Minsley, B. J.; Pastick, N. J.; Wylie, B. K.; Kass, A.; Brown, D. N.; Rey, D.; Bloss, B. R.; Ebel, B. A.; Walvoord, M. A.; Emond, A.; Daanen, R. P.

    2017-12-01

    Disturbance related to fire or hydrologic processes can cause degradation of deep (greater than 1 m) permafrost. These changes in deep permafrost have the potential to impact landscapes and infrastructure, alter the routing and distribution of surface water or groundwater, and may contribute to the flux of carbon to terrestrial and aquatic ecosystems. However, characterization of deep permafrost over large areas and with high spatial resolution is not possible with traditional remote sensing or surface observations. We make use of multiple ground-based and airborne geophysical methods, as well as numerical simulations, to better understand the distribution of permafrost and how it has changed after disturbance. At the local scale, electrical resistivity tomography (ERT) measurements are used to identify changes in permafrost characteristics to depths of up to 15 m along more than 40 100-200 m-long transects collected in interior Alaska. At select locations along these profiles, measurements of downhole nuclear magnetic resonance were made to depths of 2 m belowground in order to quantify in situ unfrozen water content and soil texture that help to constrain ERT interpretations. At the regional scale, airborne and ground-based electromagnetic data have been acquired to map the complex distribution of deep permafrost beneath and adjacent to the many lakes and streams in parts of interior Alaska. Together, these geophysical datasets help to fill a critical gap in understanding permafrost landscapes and their response to disturbance.

  8. Assessment of three mitigation techniques for permafrost protection

    DEFF Research Database (Denmark)

    Jørgensen, Anders Stuhr

    The presence of permafrost is an important aspect in civil engineering in arctic regions. The construction of engineering structures, such as road and airfield embankments, will change the thermal regime of the ground, and may lead to permafrost degradation under or adjacent to such structures....... This problem, has in the last decades, been amplified by the climate warming, which has been most evident in the arctic regions. The construction of a road embankment usually results in an increased mean annual surface temperature, which will increase the thawing of permafrost and expose the road embankment...... objective has been to study the three above-mentioned techniques and evaluate their potential for minimizing the problems with thaw settlements in permafrost areas. The air convection embankment and heat drain techniques have been tested for the implementation in the shoulders of road and airfield...

  9. Surface studies of oil-seal degradation

    Science.gov (United States)

    Smith, G. C.; Park, D.; Titchener, K. J.; Davies, R. E.; West, R. H.

    1995-11-01

    Fluoroelastomers are frequently used as engine oil-seal materials. Under certain test conditions specific fluoroelastomers may show degradation of mechanical properties. A range of fluoroelastomers of different chemical composition have been aged in simple oil/additive blends and in oil formulations equivalent to commercial blends. These were then examined using XPS, SEM/EPMA and XRD to elucidate the physical and chemical changes associated with degradation. The interaction is shown to proceed through amine catalysed post-curing of the constituent polymers. These reactions promote defluorination, embrittlement and cracking of elastomers with a consequent decline in tensile properties as fracture failure mechanisms dominate performance. Degradation of these materials was found, even in the most extreme case, to be limited to the near-surface region of the samples, to a depth of less than approximately 50 μm. Degradation was reduced in elastomers with a higher fluorine level, higher terpolymer content, and a greater extent of cross-linking.

  10. Hydro-chemical detection of permafrost degradation in the Eastern European Alps - Implications for geomorphological process studies and natural hazard assessment

    Science.gov (United States)

    Kraushaar, Sabine; Kamleitner, Sarah; Czarnowsky, Verena; Blöthe, Jan; Morche, David; Knöller, Kay; Lachner, Johannes

    2017-04-01

    The Gepatschferner glacier in the Upper Kaunertal valley is one of the fastest melting glaciers in the Eastern European Alps. With a retreat rate of around 110 m a-1 since the hydrological year 2012/ 2013, unconsolidated sediments of steep lateral moraines have been exposed to erosion, from which nowadays episodic and perennial springs well. We hypothesize that the springs indicate the melt out of dead ice lenses in areas below 2500 m, causing a potential significant morphological change in the moraines and a decrease of slope stability in the proglacial long after glacier retreat. However, permafrost degradation has not been considered so far in contemporary erosion measurements. The present study aims to identify the spring water's origin and displays first attempts of quantifying thermal erosion, which describes the matrix volume loss due to melting and drainage of ice water. Samples were routinely analyzed for temperature, electrical conductivity, δ2H, and δ18O. Results support the hypothesis that certain springs derive from melting ice of similar isotopic signature as the glacier. In a second step, chosen samples were examined for the long-lived anthropogenic nuclide 129I. Since the 1950s the atmospheric abundance of 129I has significantly increased. Its occurrence in the water samples hints a surface contact of the waters in the last 65 years. Springs of ice origin show little 129I content and are believed to derive from dead ice by the glacier. First electric resistivity measurements support the hydro-chemical results and suggest the existence of ice lenses in the subsurface. Ice ablation and discharge measurements allowed first estimates of the thermal erosion volume caused by the melt out and drainage of ice lenses.

  11. Determining the terrain characteristics related to the surface expression of subsurface water pressurization in permafrost landscapes using susceptibility modelling

    Science.gov (United States)

    Holloway, Jean E.; Rudy, Ashley C. A.; Lamoureux, Scott F.; Treitz, Paul M.

    2017-06-01

    Warming of the Arctic in recent years has led to changes in the active layer and uppermost permafrost. In particular, thick active layer formation results in more frequent thaw of the ice-rich transient layer. This addition of moisture, as well as infiltration from late season precipitation, results in high pore-water pressures (PWPs) at the base of the active layer and can potentially result in landscape degradation. To predict areas that have the potential for subsurface pressurization, we use susceptibility maps generated using a generalized additive model (GAM). As model response variables, we used active layer detachments (ALDs) and mud ejections (MEs), both formed by high PWP conditions at the Cape Bounty Arctic Watershed Observatory, Melville Island, Canada. As explanatory variables, we used the terrain characteristics elevation, slope, distance to water, topographic position index (TPI), potential incoming solar radiation (PISR), distance to water, normalized difference vegetation index (NDVI; ME model only), geology, and topographic wetness index (TWI). ALDs and MEs were accurately modelled in terms of susceptibility to disturbance across the study area. The susceptibility models demonstrate that ALDs are most probable on hill slopes with gradual to steep slopes and relatively low PISR, whereas MEs are associated with higher elevation areas, lower slope angles, and areas relatively far from water. Based on these results, this method identifies areas that may be sensitive to high PWPs and helps improve our understanding of geomorphic sensitivity to permafrost degradation.

  12. Determining the terrain characteristics related to the surface expression of subsurface water pressurization in permafrost landscapes using susceptibility modelling

    Directory of Open Access Journals (Sweden)

    J. E. Holloway

    2017-06-01

    Full Text Available Warming of the Arctic in recent years has led to changes in the active layer and uppermost permafrost. In particular, thick active layer formation results in more frequent thaw of the ice-rich transient layer. This addition of moisture, as well as infiltration from late season precipitation, results in high pore-water pressures (PWPs at the base of the active layer and can potentially result in landscape degradation. To predict areas that have the potential for subsurface pressurization, we use susceptibility maps generated using a generalized additive model (GAM. As model response variables, we used active layer detachments (ALDs and mud ejections (MEs, both formed by high PWP conditions at the Cape Bounty Arctic Watershed Observatory, Melville Island, Canada. As explanatory variables, we used the terrain characteristics elevation, slope, distance to water, topographic position index (TPI, potential incoming solar radiation (PISR, distance to water, normalized difference vegetation index (NDVI; ME model only, geology, and topographic wetness index (TWI. ALDs and MEs were accurately modelled in terms of susceptibility to disturbance across the study area. The susceptibility models demonstrate that ALDs are most probable on hill slopes with gradual to steep slopes and relatively low PISR, whereas MEs are associated with higher elevation areas, lower slope angles, and areas relatively far from water. Based on these results, this method identifies areas that may be sensitive to high PWPs and helps improve our understanding of geomorphic sensitivity to permafrost degradation.

  13. Impacts of permafrost degradation on a stream in Taylor Valley, Antarctica

    Science.gov (United States)

    Sudman, Zachary; Gooseff, Michael N.; Fountain, Andrew G.; Levy, Joseph S.; Obryk, Maciej K.; Van Horn, David

    2017-05-01

    The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (region is nearing a threshold of rapid landscape change. In 2012, substantial thermokarst development was observed along several kilometers of the west branch of Crescent Stream in Taylor Valley mostly in the form of bank failures, whereas the adjacent east branch was unaffected. The objective of this study was to quantify the changes to the stream banks of the west branch of Crescent Stream and to determine the impacts on the composition of the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change caused by thermokarst formation on the stream bank. The areal extent of the thermokarst was shown to be decreasing; however, the average vertical rate of retreat remained constant. Field measurements of bed materials indicated that the west branch and the reach downstream of the confluence (of east and west branches) consistently contained more fines than the unaffected east branch. This suggests that the finer bed material is a result of the thermokarst development on the west branch. These finer bed material compositions are likely to increase the mobility of the bed material, which will have implications for stream morphology, stream algal mat communities, and downstream aquatic ecosystems.

  14. Surface degradation of high Tc superconductors

    International Nuclear Information System (INIS)

    Lu, Q.; Larkins, G.L. Jr.; Jones, W.K.; Kennedy, R.J.; Chern, G.

    1991-01-01

    This paper reports on surface degradation studies of the YBa 2 Cu 3 O 7-x (123) and Bi-Sr-Ca-Cu-O (2223) superconducting ceramics performed in N 2 , Ar 2 , O 2 , wet and dry air. By using a non-contact, room temperature technique the time dependence of the surface impedance of both 123 and Bi-Sr-Ca-Cu-O bulk ceramics are measured from 100 Hz to 20 kHz. In humid environments the rate of degradation is dependent on the humidity and appears to be unaffected by the carrier gas. The surface impedance change due to humidity follows a power law and does not appear to saturate at a final value

  15. Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow

    Science.gov (United States)

    Kurylyk, Barret; Masaki, Masaki; Quinton, William L.; McKenzie, Jeffrey M.; Voss, Clifford I.

    2016-01-01

    Recent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near-surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau-wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near-surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three-dimensional model of subsurface water flow and coupled energy transport with freeze-thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.

  16. Mapping of permafrost surface using ground-penetrating radar at Kangerlussuaq Airport, western Greenland

    DEFF Research Database (Denmark)

    Jørgensen, Anders Stuhr; Andreasen, Frank

    2007-01-01

    Kangerlussuaq Airport is located at 67°N and 51°W in the zone of continuous permafrost in western Greenland. Its proximity to the Greenlandic ice sheet results in a dry sub-arctic climate with a mean annual temperature of −5.7 °C. The airport is built on a river terrace mostly consisting of fluvial...

  17. Modeling the Space-Time Destiny of Pan-Arctic Permafrost DOC in a Global Land Surface Model: Feedback Implications

    Science.gov (United States)

    Bowring, S.; Lauerwald, R.; Guenet, B.; Zhu, D.; Ciais, P.

    2017-12-01

    Most global climate models do not represent the unique permafrost soil environment and its respective processes. This significantly contributes to uncertainty in estimating their responses, and that of the planet at large, to warming. Here, the production, transport and atmospheric release of dissolved organic carbon (DOC) from high-latitude permafrost soils into inland waters and the ocean is explicitly represented for the first time in the land surface component (ORCHIDEE-MICT) of a CMIP6 global climate model (IPSL). This work merges two models that are able to mechanistically simulate complex processes for 1) snow, ice and soil phenomena in high latitude environments, and 2) DOC production and lateral transport through soils and the river network, respectively, at 0.5° to 2° resolution. The resulting model is subjected to a wide range of input forcing data, parameter testing and contentious feedback phenomena, including microbial heat generation as the active layer deepens. We present results for the present and future Pan-Arctic and Eurasia, with a focus on the Lena and Mackenzie River basins, and show that soil DOC concentrations, their riverine transport and atmospheric evasion are reasonably well represented as compared to observed stocks, fluxes and seasonality. We show that most basins exhibit large increases in DOC transport and riverine CO2 evasion across the suite of RCP scenarios to 2100. We also show that model output is strongly influenced by choice of input forcing data. The riverine component of what is known as the `boundless carbon cycle' is little-recognized in global climate modeling. Hydrological mobilization to the river network results either in sedimentary settling or atmospheric `evasion', presently amounting to 0.5-1.8 PgC yr-1. Our work aims at filling in these knowledge gaps, and the response of these DOC-related processes to thermal forcing. Potential feedbacks owing to such a response are of particular relevance, given the magnitude

  18. Study of environmental degradation of silver surface

    Energy Technology Data Exchange (ETDEWEB)

    Aguas, H.; Silva, R.J.C.; Viegas, M.; Pereira, L.; Fortunato, E.; Martins, R. [Materials Science Department, CENIMAT/I3N, FCT-UNL, Campus de Caparica (Portugal)

    2008-05-15

    To evaluate the evolution of a dark film formation on silver surface objects, several coupons were catalogued and place inside a museum, located in an urban area. The changes on these samples were measured by spectroscopic ellipsometry, in periods of months. This technique allows the reduction of the coupons exposure time, in several months, due to its high sensitivity to surface modifications, with acceptable results for the evaluation of its degradation. The thicknesses of the degradation layers and the optical properties of silver oxide, chloride and sulphide reference samples were determined using a mixture of Tauc-Lorentz and Drude models. The composition of the silver corrosion layer was determined by fitting the layer using a Bruggeman Effective Medium Approximation (BEMA) of the three products plus voids. It was found that the thickness of the layer depends in the placement of the coupons, namely, inside or outside displayers. The average film thickness after 6 months was of 180 Aa and 280 Aa, inside and outside the displayers, respectively. The main compounds found in the layers were the silver chlorides and sulphides, which composition changed with the thickness of the layer, and the exposition time. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Permafrost Hazards and Linear Infrastructure

    Science.gov (United States)

    Stanilovskaya, Julia; Sergeev, Dmitry

    2014-05-01

    The international experience of linear infrastructure planning, construction and exploitation in permafrost zone is being directly tied to the permafrost hazard assessment. That procedure should also consider the factors of climate impact and infrastructure protection. The current global climate change hotspots are currently polar and mountain areas. Temperature rise, precipitation and land ice conditions change, early springs occur more often. The big linear infrastructure objects cross the territories with different permafrost conditions which are sensitive to the changes in air temperature, hydrology, and snow accumulation which are connected to climatic dynamics. One of the most extensive linear structures built on permafrost worldwide are Trans Alaskan Pipeline (USA), Alaska Highway (Canada), Qinghai-Xizang Railway (China) and Eastern Siberia - Pacific Ocean Oil Pipeline (Russia). Those are currently being influenced by the regional climate change and permafrost impact which may act differently from place to place. Thermokarst is deemed to be the most dangerous process for linear engineering structures. Its formation and development depend on the linear structure type: road or pipeline, elevated or buried one. Zonal climate and geocryological conditions are also of the determining importance here. All the projects are of the different age and some of them were implemented under different climatic conditions. The effects of permafrost thawing have been recorded every year since then. The exploration and transportation companies from different countries maintain the linear infrastructure from permafrost degradation in different ways. The highways in Alaska are in a good condition due to governmental expenses on annual reconstructions. The Chara-China Railroad in Russia is under non-standard condition due to intensive permafrost response. Standards for engineering and construction should be reviewed and updated to account for permafrost hazards caused by the

  20. Unraveling of permafrost hydrological variabilities on Central Qinghai-Tibet Plateau using stable isotopic technique.

    Science.gov (United States)

    Yang, Yuzhong; Wu, Qingbai; Hou, Yandong; Zhang, Zhongqiong; Zhan, Jing; Gao, Siru; Jin, Huijun

    2017-12-15

    Permafrost degradation on the Qinghai-Tibet Plateau (QTP) will substantially alter the surface runoff discharge and generation, which changes the recharge processes and influences the hydrological cycle on the QTP. Hydrological connections between different water bodies and the influence of thawing permafrost (ground ice) are not well understood on the QTP. This study applied water stable isotopic method to investigate the permafrost hydrological variabilities in Beiluhe Basin (BLB) on Central QTP. Isotopic variations of precipitation, river flow, thermokarst lake, and near-surface ground ice were identified to figure out the moisture source of them, and to elaborate the hydrological connections in permafrost region. Results suggested that isotopic seasonalities in precipitation is evident, it is showing more positive values in summer seasons, and negative values in winter seasons. Stable isotopes of river flow are mainly distributed in the range of precipitation which is indicative of important replenishment from precipitation. δ 18 O, δD of thermokarst lakes are more positive than precipitation, indicating of basin-scale evaporation of lake water. Comparison of δ I values in different water bodies shows that hydrology of thermokarst lakes was related to thawing of permafrost (ground ice) and precipitation. Near-surface ground ice in BLB exhibits different isotopic characteristics, and generates a special δD-δ 18 O relationship (freezing line): δD=5.81δ 18 O-23.02, which reflects typical freezing of liquid water. From isotopic analysis, it is inferred that near-surface ground ice was mainly recharged by precipitation and active layer water. Stable isotopic and conceptual model is suggestive of striking hydrological connections between precipitation, river flow, thermokarst lake, and ground ice under degrading permafrost. This research provides fundamental comprehensions into the hydrological processes in permafrost regions on QTP, which should be considered

  1. The application of refraction seismics in alpine permafrost studies

    Science.gov (United States)

    Draebing, Daniel

    2017-04-01

    Permafrost studies in alpine environments focus on landslides from permafrost-affected rockwalls, landslide deposits or periglacial sediment dynamics. Mechanical properties of soils or rocks are influenced by permafrost and changed strength properties affect these periglacial processes. To assess the effects of permafrost thaw and degradation, monitoring techniques for permafrost distribution and active-layer thaw are required. Seismic wave velocities are sensitive to freezing and, therefore, refraction seismics presents a valuable tool to investigate permafrost in alpine environments. In this study, (1) laboratory and field applications of refraction seismics in alpine environments are reviewed and (2) data are used to quantify effects of rock properties (e.g. lithology, porosity, anisotropy, saturation) on p-wave velocities. In the next step, (3) influence of environmental factors are evaluated and conclusions drawn on permafrost differentiation within alpine periglacial landforms. This study shows that p-wave velocity increase is susceptible to porosity which is pronounced in high-porosity rocks. In low-porosity rocks, p-wave velocity increase is controlled by anisotropy decrease due to ice pressure (Draebing and Krautblatter, 2012) which enables active-layer and permafrost differentiation at rockwall scale (Krautblatter and Draebing, 2014; Draebing et al., 2016). However, discontinuity distribution can result in high anisotropy effects on seismic velocities which can impede permafrost differentiation (Phillips et al., 2016). Due to production or deposition history, porosity can show large spatial differences in deposited landforms. Landforms with large boulders such as rock glaciers and moraines show highest p-wave velocity differences between active-layer and permafrost which facilitates differentiation (Draebing, 2016). Saturation with water is essential for the successful application of refraction seismics for permafrost detection and can be controlled at

  2. Mapping of permafrost surface and active layer properties using GPR: a comparison of frequency dependencies

    DEFF Research Database (Denmark)

    Gacitua, Guisella; Uribe, José Andrés; Tamstorf, Mikkel Peter

    2011-01-01

    Ground penetrating radar (GPR) was used to detect internal features and conditions in the active layer of Zackenberg valley in North-East Greenland. For about 16 years there has been a monitoring programme that registers the physical and biological processes in the ecosystem.We aim to improve...... the monitoring accuracy of the active layer development and estimated soil water content. We used two different GPR frequencies to study their performance in High-Arctic cryoturbated soils. Here we present the analysis of the signal received by quantifying the power of the signal that is reflected from the top...... are suitable to measure thickness and to detect features in the active layer, the 400 MHz gives a better impression of the influence of the dielectric contrast effect from top of the permafrost zone which can be used to quantify the soil water content....

  3. CryoGRIDequi - a new equilibrium permafrost model applied for Norway

    Science.gov (United States)

    Gisnås, K.; Etzelmuller, B.; Farbrot, H.; Westermann, S.; Schuler, T.

    2011-12-01

    The thermal regime of permafrost is likely to change significantly in response to the predicted climate warming, with associated warming and degradation of permafrost. Knowledge about the spatial distribution and temperatures of permafrost is therefore crucial to understand the associated geomorphological and bio-chemical consequences. Based on spatially distributed equilibrium models (CryoGRIDequi) this presentation will focus on the effect of snow cover and organic material on the regional distribution of permafrost in Norway. In Norway, the good availability of spatially distributed data on meteorological variables, vegetation, petrophysics and sediment cover allows for an implementation of soil models with relatively high resolution, in our case 1km2. CryoGRIDequi comprises implementations of both the TTOP-model and the Kudryavtsev approach. The model defines temperature at the top of permafrost from air temperatures based on seasonal n-factors, parameterizing the vegetation and snow cover, and the conductivity ratio between frozen and thawed states in the active layer. The models are run with operationally gridded temperature- and snow data from the period 1960-2010, provided by the Norwegian Meteorological Institute and the Norwegian Water and Energy Directorate (senorge.no). Parameterization of the model is based on data from several air/ground and snow depth stations established in various mountain sites. The modeling results are validated with 140 sites all over Norway measuring ground surface temperature, 20 shallow boreholes equipped with temperature monitoring logger devices and maps of palsa- and rock glacier locations. The modeled permafrost distribution is in good agreement with observations. Sporadic permafrost under organic cover, which is absent in previous regional modeling procedures, is now well reproduced. According to the model results, approximately 6% of the total mainland area in Norway is presently underlain by permafrost. Of the total

  4. Vulnerability and feedbacks of permafrost to climate change

    Science.gov (United States)

    Guido Grosse; Vladimir Romanovsky; Torre Jorgenson; Katey Walter Anthony; Jerry Brown; Pier Paul Overduin; Alfred. Wegener

    2011-01-01

    The effects of permafrost degradation on terrestrial and offshore environments in polar regions and on the Earth's atmosphere are significant. Field-based observations, remote sensing, and modeling document regional warming and thawing of permafrost. However, major research questions regarding vulnerability of permafrost to thawing, the projected decline in...

  5. Using Modeling Tools to Better Understand Permafrost Hydrology

    Directory of Open Access Journals (Sweden)

    Clément Fabre

    2017-06-01

    Full Text Available Modification of the hydrological cycle and, subsequently, of other global cycles is expected in Arctic watersheds owing to global change. Future climate scenarios imply widespread permafrost degradation caused by an increase in air temperature, and the expected effect on permafrost hydrology is immense. This study aims at analyzing, and quantifying the daily water transfer in the largest Arctic river system, the Yenisei River in central Siberia, Russia, partially underlain by permafrost. The semi-distributed SWAT (Soil and Water Assessment Tool hydrological model has been calibrated and validated at a daily time step in historical discharge simulations for the 2003–2014 period. The model parameters have been adjusted to embrace the hydrological features of permafrost. SWAT is shown capable to estimate water fluxes at a daily time step, especially during unfrozen periods, once are considered specific climatic and soils conditions adapted to a permafrost watershed. The model simulates average annual contribution to runoff of 263 millimeters per year (mm yr−1 distributed as 152 mm yr−1 (58% of surface runoff, 103 mm yr−1 (39% of lateral flow and 8 mm yr−1 (3% of return flow from the aquifer. These results are integrated on a reduced basin area downstream from large dams and are closer to observations than previous modeling exercises.

  6. Influences of Climate Warming and Facility Management on Continuous Permafrost at Matterhorn Glacier Paradise, Zermatt, Swiss Alps.

    Science.gov (United States)

    King, Lorenz; Duishonakunov, Murataly; Imbery, Stephan

    2014-05-01

    Glacier Paradise is the glacier palace. Since summer 2011 this tourist attraction can be accessed via two elevators leading to an ice tunnel about 12 meters below the glaciers surface. Interesting thermal interactions exist between the permafrost bedrock that is in direct contact to the glacier ice. Great care has to be taken that there is no heat transfer from buildings to the glacier ice. Degradation of permafrost due to climatic change and human interference may become a serious threat to many installations of high mountain tourist centers. These facilities need appropriate management. Permafrost scientists may provide the necessary expertise for a proper hazard management.

  7. Permafrost Organic Carbon Mobilization From the Watershed to the Colville River Delta: Evidence From 14C Ramped Pyrolysis and Lignin Biomarkers

    Science.gov (United States)

    Zhang, Xiaowen; Bianchi, Thomas S.; Cui, Xingqian; Rosenheim, Brad E.; Ping, Chien-Lu; Hanna, Andrea J. M.; Kanevskiy, Mikhail; Schreiner, Kathryn M.; Allison, Mead A.

    2017-11-01

    The deposition of terrestrial-derived permafrost particulate organic carbon (POC) has been recorded in major Arctic river deltas. However, associated transport pathways of permafrost POC from the watershed to the coast have not been well constrained. Here we utilized a combination of ramped pyrolysis-oxidation radiocarbon analysis (RPO 14C) along with lignin biomarkers, to track the linkages between soils and river and delta sediments. Surface and deep soils showed distinct RPO thermographs which may be related to degradation and organo-mineral interaction. Soil material in the bed load of the river channel was mostly derived from deep old permafrost. Both surface and deep soils were transported and deposited to the coast. Hydrodynamic sorting and barrier island protection played important roles in terrestrial-derived permafrost POC deposition near the coast. On a large scale, ice processes (e.g., ice gauging and strudel scour) and ocean currents controlled the transport and distribution of permafrost POC on the Beaufort Shelf.

  8. Improving Permafrost Hydrology Prediction Through Data-Model Integration

    Science.gov (United States)

    Wilson, C. J.; Andresen, C. G.; Atchley, A. L.; Bolton, W. R.; Busey, R.; Coon, E.; Charsley-Groffman, L.

    2017-12-01

    The CMIP5 Earth System Models were unable to adequately predict the fate of the 16GT of permafrost carbon in a warming climate due to poor representation of Arctic ecosystem processes. The DOE Office of Science Next Generation Ecosystem Experiment, NGEE-Arctic project aims to reduce uncertainty in the Arctic carbon cycle and its impact on the Earth's climate system by improved representation of the coupled physical, chemical and biological processes that drive how much buried carbon will be converted to CO2 and CH4, how fast this will happen, which form will dominate, and the degree to which increased plant productivity will offset increased soil carbon emissions. These processes fundamentally depend on permafrost thaw rate and its influence on surface and subsurface hydrology through thermal erosion, land subsidence and changes to groundwater flow pathways as soil, bedrock and alluvial pore ice and massive ground ice melts. LANL and its NGEE colleagues are co-developing data and models to better understand controls on permafrost degradation and improve prediction of the evolution of permafrost and its impact on Arctic hydrology. The LANL Advanced Terrestrial Simulator was built using a state of the art HPC software framework to enable the first fully coupled 3-dimensional surface-subsurface thermal-hydrology and land surface deformation simulations to simulate the evolution of the physical Arctic environment. Here we show how field data including hydrology, snow, vegetation, geochemistry and soil properties, are informing the development and application of the ATS to improve understanding of controls on permafrost stability and permafrost hydrology. The ATS is being used to inform parameterizations of complex coupled physical, ecological and biogeochemical processes for implementation in the DOE ACME land model, to better predict the role of changing Arctic hydrology on the global climate system. LA-UR-17-26566.

  9. Scaling-up permafrost thermal measurements in western Alaska using an ecotype approach

    Directory of Open Access Journals (Sweden)

    W. L. Cable

    2016-10-01

    Full Text Available Permafrost temperatures are increasing in Alaska due to climate change and in some cases permafrost is thawing and degrading. In areas where degradation has already occurred the effects can be dramatic, resulting in changing ecosystems, carbon release, and damage to infrastructure. However, in many areas we lack baseline data, such as subsurface temperatures, needed to assess future changes and potential risk areas. Besides climate, the physical properties of the vegetation cover and subsurface material have a major influence on the thermal state of permafrost. These properties are often directly related to the type of ecosystem overlaying permafrost. In this paper we demonstrate that classifying the landscape into general ecotypes is an effective way to scale up permafrost thermal data collected from field monitoring sites. Additionally, we find that within some ecotypes the absence of a moss layer is indicative of the absence of near-surface permafrost. As a proof of concept, we used the ground temperature data collected from the field sites to recode an ecotype land cover map into a map of mean annual ground temperature ranges at 1 m depth based on analysis and clustering of observed thermal regimes. The map should be useful for decision making with respect to land use and understanding how the landscape might change under future climate scenarios.

  10. Modeling thermal dynamics of active layer soils and near-surface permafrost using a fully coupled water and heat transport model

    Science.gov (United States)

    Jiang, Yueyang; Zhuang, Qianlai; O'Donnell, Jonathan A.

    2012-01-01

    Thawing and freezing processes are key components in permafrost dynamics, and these processes play an important role in regulating the hydrological and carbon cycles in the northern high latitudes. In the present study, we apply a well-developed soil thermal model that fully couples heat and water transport, to simulate the thawing and freezing processes at daily time steps across multiple sites that vary with vegetation cover, disturbance history, and climate. The model performance was evaluated by comparing modeled and measured soil temperatures at different depths. We use the model to explore the influence of climate, fire disturbance, and topography (north- and south-facing slopes) on soil thermal dynamics. Modeled soil temperatures agree well with measured values for both boreal forest and tundra ecosystems at the site level. Combustion of organic-soil horizons during wildfire alters the surface energy balance and increases the downward heat flux through the soil profile, resulting in the warming and thawing of near-surface permafrost. A projection of 21st century permafrost dynamics indicates that as the climate warms, active layer thickness will likely increase to more than 3 meters in the boreal forest site and deeper than one meter in the tundra site. Results from this coupled heat-water modeling approach represent faster thaw rates than previously simulated in other studies. We conclude that the discussed soil thermal model is able to well simulate the permafrost dynamics and could be used as a tool to analyze the influence of climate change and wildfire disturbance on permafrost thawing.

  11. Degradation state of organic matter in surface sediments from the Southern Beaufort Sea: a lipid approach

    Directory of Open Access Journals (Sweden)

    J.-F. Rontani

    2012-09-01

    Full Text Available For the next decades significant climatic changes should occur in the Arctic zone. The expected destabilisation of permafrost and its consequences for hydrology and plant cover should increase the input of terrigenous carbon to coastal seas. Consequently, the relative importance of the fluxes of terrestrial and marine organic carbon to the seafloor will likely change, strongly impacting the preservation of organic carbon in Arctic marine sediments. Here, we investigated the lipid content of surface sediments collected on the Mackenzie basin in the Beaufort Sea. Particular attention was given to biotic and abiotic degradation products of sterols and monounsaturated fatty acids. By using sitosterol and campesterol degradation products as tracers of the degradation of terrestrial higher plant inputs and brassicasterol degradation products as tracers of degradation of phytoplanktonic organisms, it could be observed that autoxidation, photooxidation and biodegradation processes act much more intensively on higher plant debris than on phytoplanktonic organisms. Examination of oxidation products of monounsaturated fatty acids showed that photo- and autoxidation processes act more intensively on bacteria than on phytodetritus. Enhanced damages induced by singlet oxygen (transferred from senescent phytoplanktonic cells in bacteria were attributed to the lack of an adapted antioxidant system in these microorganisms. The strong oxidative stress observed in the sampled sediments resulted in the production of significant amounts of epoxy acids and unusually high proportions of monounsaturated fatty acids with a trans double bond. The formation of epoxy acids was attributed to peroxygenases (enzymes playing a protective role against the deleterious effects of fatty acid hydroperoxides in vivo, while cis/trans isomerisation was probably induced by thiyl radicals produced during the reaction of thiols with hydroperoxides. Our results confirm the

  12. Degradation state of organic matter in surface sediments from the Southern Beaufort Sea: a lipid approach

    Science.gov (United States)

    Rontani, J.-F.; Charriere, B.; Petit, M.; Vaultier, F.; Heipieper, H. J.; Link, H.; Chaillou, G.; Sempéré, R.

    2012-09-01

    For the next decades significant climatic changes should occur in the Arctic zone. The expected destabilisation of permafrost and its consequences for hydrology and plant cover should increase the input of terrigenous carbon to coastal seas. Consequently, the relative importance of the fluxes of terrestrial and marine organic carbon to the seafloor will likely change, strongly impacting the preservation of organic carbon in Arctic marine sediments. Here, we investigated the lipid content of surface sediments collected on the Mackenzie basin in the Beaufort Sea. Particular attention was given to biotic and abiotic degradation products of sterols and monounsaturated fatty acids. By using sitosterol and campesterol degradation products as tracers of the degradation of terrestrial higher plant inputs and brassicasterol degradation products as tracers of degradation of phytoplanktonic organisms, it could be observed that autoxidation, photooxidation and biodegradation processes act much more intensively on higher plant debris than on phytoplanktonic organisms. Examination of oxidation products of monounsaturated fatty acids showed that photo- and autoxidation processes act more intensively on bacteria than on phytodetritus. Enhanced damages induced by singlet oxygen (transferred from senescent phytoplanktonic cells) in bacteria were attributed to the lack of an adapted antioxidant system in these microorganisms. The strong oxidative stress observed in the sampled sediments resulted in the production of significant amounts of epoxy acids and unusually high proportions of monounsaturated fatty acids with a trans double bond. The formation of epoxy acids was attributed to peroxygenases (enzymes playing a protective role against the deleterious effects of fatty acid hydroperoxides in vivo), while cis/trans isomerisation was probably induced by thiyl radicals produced during the reaction of thiols with hydroperoxides. Our results confirm the important role played by abiotic

  13. Mapping permafrost with airborne electromagnetics

    Science.gov (United States)

    Minsley, B. J.; Ball, L. B.; Bloss, B. R.; Kass, A.; Pastick, N.; Smith, B. D.; Voss, C. I.; Walsh, D. O.; Walvoord, M. A.; Wylie, B. K.

    2014-12-01

    Permafrost is a key characteristic of cold region landscapes, yet detailed assessments of how the subsurface distribution of permafrost impacts the environment, hydrologic systems, and infrastructure are lacking. Data acquired from several airborne electromagnetic (AEM) surveys in Alaska provide significant new insight into the spatial extent of permafrost over larger areas (hundreds to thousands of square kilometers) than can be mapped using ground-based geophysical methods or through drilling. We compare several AEM datasets from different areas of interior Alaska, and explore the capacity of these data to infer geologic structure, permafrost extent, and related hydrologic processes. We also assess the impact of fires on permafrost by comparing data from different burn years within similar geological environments. Ultimately, interpretations rely on understanding the relationship between electrical resistivity measured by AEM surveys and the physical properties of interest such as geology, permafrost, and unfrozen water content in the subsurface. These relationships are often ambiguous and non-unique, so additional information is useful for reducing uncertainty. Shallow (upper ~1m) permafrost and soil characteristics identified from remotely sensed imagery and field observations help to constrain and aerially extend near-surface AEM interpretations, where correlations between the AEM and remote sensing data are identified using empirical multivariate analyses. Surface nuclear magnetic resonance (sNMR) measurements quantify the contribution of unfrozen water at depth to the AEM-derived electrical resistivity models at several locations within one survey area. AEM surveys fill a critical data gap in the subsurface characterization of permafrost environments and will be valuable in future mapping and monitoring programs in cold regions.

  14. Surface degradation of nanocrystalline zirconia dental implants

    NARCIS (Netherlands)

    Ocelík, Václav; Schepke, Ulf; Rasoul, Hamid Haji; Cune, Marco S.; De Hosson, Jeff Th M.

    2017-01-01

    Yttria-stabilized zirconia prepared by hot isostatic pressing represents attractive material for biomedical applications. In this work the degradation of yttria-stabilized zirconia dental implants abutments due to the tetragonal to monoclinic phase transformation after one year of clinical use was

  15. Rapid disturbances in Arctic permafrost regions (Invited)

    Science.gov (United States)

    Grosse, G.; Romanovsky, V. E.; Arp, C. D.; Jones, B. M.

    2013-12-01

    ponds have been forming indicate a broad range of possible biogeochemical feedbacks that require further study. Finally, thermokarst lake drainage observed in regions of continuous permafrost shows that local permafrost degradation, such as thermo-erosional gully formation, may increase permafrost extent in a region, in particular by new permafrost aggradation in freshly exposed, refreezing lake basin sediments. Thermokarst lake drainage across all types of permafrost extent increases habitat diversity, is important for regional biogeochemical cycling, and results in carbon sequestration. While all three disturbance types differ in spatial scale and current abundance, they also point at specific vulnerabilities of permafrost landscapes that are tied to local factors such as ground ice, highlight critical knowledge gaps for predictive ecosystem and biogeochemical models, and indicate the potential for rapid, substantial, and surprising changes in a future warmer Arctic.

  16. Landscape effects of wildfire on permafrost distribution in interior Alaska derived from remote sensing

    Science.gov (United States)

    Brown, Dana R. N.; Jorgenson, M. Torre; Kielland, Knut; Verbyla, David L.; Prakash, Anupma; Koch, Joshua C.

    2016-01-01

    Climate change coupled with an intensifying wildfire regime is becoming an important driver of permafrost loss and ecosystem change in the northern boreal forest. There is a growing need to understand the effects of fire on the spatial distribution of permafrost and its associated ecological consequences. We focus on the effects of fire a decade after disturbance in a rocky upland landscape in the interior Alaskan boreal forest. Our main objectives were to (1) map near-surface permafrost distribution and drainage classes and (2) analyze the controls over landscape-scale patterns of post-fire permafrost degradation. Relationships among remote sensing variables and field-based data on soil properties (temperature, moisture, organic layer thickness) and vegetation (plant community composition) were analyzed using correlation, regression, and ordination analyses. The remote sensing data we considered included spectral indices from optical datasets (Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operational Land Imager (OLI)), the principal components of a time series of radar backscatter (Advanced Land Observing Satellite—Phased Array type L-band Synthetic Aperture Radar (ALOS-PALSAR)), and topographic variables from a Light Detection and Ranging (LiDAR)-derived digital elevation model (DEM). We found strong empirical relationships between the normalized difference infrared index (NDII) and post-fire vegetation, soil moisture, and soil temperature, enabling us to indirectly map permafrost status and drainage class using regression-based models. The thickness of the insulating surface organic layer after fire, a measure of burn severity, was an important control over the extent of permafrost degradation. According to our classifications, 90% of the area considered to have experienced high severity burn (using the difference normalized burn ratio (dNBR)) lacked permafrost after fire. Permafrost thaw, in turn, likely increased drainage and resulted in

  17. Surface CO2 Exchange Dynamics across a Climatic Gradient in McKenzie Valley: Effect of Landforms, Climate and Permafrost

    Directory of Open Access Journals (Sweden)

    Natalia Startsev

    2016-11-01

    Full Text Available Northern regions are experiencing considerable climate change affecting the state of permafrost, peat accumulation rates, and the large pool of carbon (C stored in soil, thereby emphasizing the importance of monitoring surface C fluxes in different landform sites along a climate gradient. We studied surface net C exchange (NCE and ecosystem respiration (ER across different landforms (upland, peat plateau, collapse scar in mid-boreal to high subarctic ecoregions in the Mackenzie Valley of northwestern Canada for three years. NCE and ER were measured using automatic CO2 chambers (ADC, Bioscientific LTD., Herts, England, and soil respiration (SR was measured with solid state infrared CO2 sensors (Carbocaps, Vaisala, Vantaa, Finland using the concentration gradient technique. Both NCE and ER were primarily controlled by soil temperature in the upper horizons. In upland forest locations, ER varied from 583 to 214 g C·m−2·year−1 from mid-boreal to high subarctic zones, respectively. For the bog and peat plateau areas, ER was less than half that at the upland locations. Of SR, nearly 75% was generated in the upper 5 cm layer composed of live bryophytes and actively decomposing fibric material. Our results suggest that for the upland and bog locations, ER significantly exceeded NCE. Bryophyte NCE was greatest in continuously waterlogged collapsed areas and was negligible in other locations. Overall, upland forest sites were sources of CO2 (from 64 g·C·m−2·year−1 in the high subarctic to 588 g C·m−2·year−1 in mid-boreal zone; collapsed areas were sinks of C, especially in high subarctic (from 27 g·C·m−2 year−1 in mid-boreal to 86 g·C·m−2·year−1 in high subarctic and peat plateaus were minor sources (from 153 g·C·m−2·year−1 in mid-boreal to 6 g·C·m−2·year−1 in high subarctic. The results are important in understanding how different landforms are responding to climate change and would be useful in modeling the

  18. High risk of permafrost thaw

    Energy Technology Data Exchange (ETDEWEB)

    Schuur, E.A.G.; Abbott, B.; Koven, C.D,; Riley, W.J.; Subin, Z.M.; al, et

    2011-11-01

    In the Arctic, temperatures are rising fast, and permafrost is thawing. Carbon released to the atmosphere from permafrost soils could accelerate climate change, but the likely magnitude of this effect is still highly uncertain. A collective estimate made by a group of permafrost experts, including myself, is that carbon could be released more quickly than models currently suggest, and at levels that are cause for serious concern. While our models of carbon emission from permafrost thaw are lacking, experts intimately familiar with these landscapes and processes have accumulated knowledge about what they expect to happen, based on both quantitative data and qualitative understanding of these systems. We (the authors of this piece) attempted to quantify this expertise through a survey developed over several years, starting in 2009. Our survey asked experts what percentage of surface permafrost they thought was likely to thaw, how much carbon would be released, and how much of that would be methane, for three time periods and under four warming scenarios that are part of the new IPCC Fifth Assessment Report.

  19. Impacts of a decadal drainage disturbance on surface-atmosphere fluxes of carbon dioxide in a permafrost ecosystem

    Science.gov (United States)

    Kittler, Fanny; Burjack, Ina; Corradi, Chiara A. R.; Heimann, Martin; Kolle, Olaf; Merbold, Lutz; Zimov, Nikita; Zimov, Sergey; Göckede, Mathias

    2016-09-01

    Hydrologic conditions are a major controlling factor for carbon exchange processes in high-latitude ecosystems. The presence or absence of water-logged conditions can lead to significant shifts in ecosystem structure and carbon cycle processes. In this study, we compared growing season CO2 fluxes of a wet tussock tundra ecosystem from an area affected by decadal drainage to an undisturbed area on the Kolyma floodplain in northeastern Siberia. For this comparison we found the sink strength for CO2 in recent years (2013-2015) to be systematically reduced within the drained area, with a minor increase in photosynthetic uptake due to a higher abundance of shrubs outweighed by a more pronounced increase in respiration due to warmer near-surface soil layers. Still, in comparison to the strong reduction of fluxes immediately following the drainage disturbance in 2005, recent CO2 exchange with the atmosphere over this disturbed part of the tundra indicate a higher carbon turnover, and a seasonal amplitude that is comparable again to that within the control section. This indicates that the local permafrost ecosystem is capable of adapting to significantly different hydrologic conditions without losing its capacity to act as a net sink for CO2 over the growing season. The comparison of undisturbed CO2 flux rates from 2013-2015 to the period of 2002-2004 indicates that CO2 exchange with the atmosphere was intensified, with increased component fluxes (ecosystem respiration and gross primary production) over the past decade. Net changes in CO2 fluxes are dominated by a major increase in photosynthetic uptake, resulting in a stronger CO2 sink in 2013-2015. Application of a MODIS-based classification scheme to separate the growing season into four sub-seasons improved the interpretation of interannual variability by illustrating the systematic shifts in CO2 uptake patterns that have occurred in this ecosystem over the past 10 years and highlighting the important role of the late

  20. Analysis of surface degradation of high density polyethylene (HDPE ...

    Indian Academy of Sciences (India)

    Unknown

    Analysis of surface degradation of high density polyethylene (HDPE) insulation ... ammonium chloride as the contaminant, in high density polyethylene ..... liquid in the material. When diffusion is driven by the concentration gradient and if there is no chemical change between liquid and material, this would result in mass.

  1. Surface degradation behaviour of sodium borophosphate glass in ...

    Indian Academy of Sciences (India)

    Administrator

    corrosion mechanism were different in acid and alkali media. Keywords. Borophosphate glass; surface degradation; aqueous media. 1. Introduction. Phosphate glasses and glass–ceramics are useful for appli- cations such as bone transplantation, glass–to–metal seals, containment of radioactive wastes, fast ion conduc-.

  2. Soil organic matter decomposition and temperature sensitivity after forest fire in permafrost regions in Canada

    Science.gov (United States)

    Aaltonen, Heidi; Palviainen, Marjo; Köster, Kajar; Berninger, Frank; Pumpanen, Jukka

    2017-04-01

    On the Northern Hemisphere, 24% of soils are underlain by permafrost. These soils contain 50% of the global soil carbon pool. The Northern Hemisphere is also the region which is predicted to be most affected by climate warming and this causes uncertainties over the future of the permafrost. It has been estimated that 25% of permafrost might thaw by 2100, exposing previously frozen carbon pools to decomposition. In addition, global warming is expected to cause increase in the frequency of wild fires, which further increase permafrost melting by removing the insulating organic surface layer. The amount of released soil carbon from permafrost soils after forest fire is affected by degradability and temperature sensitivity of the soil organic matter, as well as soil depth and the stage of succession. Yet the common effect of these factors remains unclear. We studied how soil respiration and its temperature sensitivity (Q10) vary in different depths and within time by taking soil samples from different fire chronosequence areas (burned 3, 25, 46 and 100 years ago) from permafrost region in Northern Canada (Yukon and Northwest Territories, along Dempster Highway). The samples from three different depths (5, 10 and 30 cm) were incubated in four different temperatures (1, 7, 13 and 19°C) over 24h. Our results showed that the CO2 fluxes followed the stages of succession, with recently burned sites having lowest rates. The organic matter at 5 cm depth proved to be more labile and temperature sensitive than in deeper depths. The Q10 values, however, did not differ between sites, excluding 30 cm at the most recently burned site that had a significantly higher Q10 value than the other sites. The results implicate that heterotrophic soil respiration decreases on permafrost regions during the first stages after forest fire. At the same time the temperature sensitivity in deeper soil layers may increase.

  3. Fossil organic matter characteristics in permafrost deposits of the northeast Siberian Arctic

    Science.gov (United States)

    Lutz Schirrmeister; Guido Grosse; Sebastian Wetterich; Pier Paul Overduin; Jens Straub; Edward A.G. Schuur; Hans-Wolfgang. Hubberton

    2011-01-01

    Permafrost deposits constitute a large organic carbon pool highly vulnerable to degradation and potential carbon release due to global warming. Permafrost sections along coastal and river bank exposures in NE Siberia were studied for organic matter (OM) characteristics and ice content. OM stored in Quaternary permafrost grew, accumulated, froze, partly decomposed, and...

  4. Thawing of permafrost may disturb historic cattle burial grounds in East Siberia

    Directory of Open Access Journals (Sweden)

    Boris A. Revich

    2011-11-01

    Full Text Available Climate warming in the Arctic may increase the risk of zoonoses due to expansion of vector habitats, improved chances of vector survival during winter, and permafrost degradation. Monitoring of soil temperatures at Siberian cryology control stations since 1970 showed correlations between air temperatures and the depth of permafrost layer that thawed during summer season. Between 1900s and 1980s, the temperature of surface layer of permafrost increased by 2–4°C; and a further increase of 3°C is expected. Frequent outbreaks of anthrax caused death of 1.5 million deer in Russian North between 1897 and 1925. Anthrax among people or cattle has been reported in 29,000 settlements of the Russian North, including more than 200 Yakutia settlements, which are located near the burial grounds of cattle that died from anthrax. Statistically significant positive trends in annual average temperatures were established in 8 out of 17 administrative districts of Yakutia for which sufficient meteorological data were available. At present, it is not known whether further warming of the permafrost will lead to the release of viable anthrax organisms. Nevertheless, we suggest that it would be prudent to undertake careful monitoring of permafrost conditions in all areas where an anthrax outbreak had occurred in the past.

  5. Resilience and vulnerability of permafrost to climate change

    Science.gov (United States)

    M.Torre Jorgenson; Vladimir Romanovsky; Jennifer Harden; Yuri Shur; Jonathan O' Donnell; Edward A.G. Schuur; Mikhail Kanevskiy; Sergei. Marchenko

    2010-01-01

    The resilience and vulnerability of permafrost to climate change depends on complex interactions among topography, water, soil, vegetation, and snow, which allow permafrost to persist at mean annual air temperatures (MAATs) as high as +2 °C and degrade at MAATs as low as -20°C. To assess these interactions, we compiled existing data and tested effects of varying...

  6. Irradiation of bioresorbable biomaterials for controlled surface degradation

    DEFF Research Database (Denmark)

    Simpson, M.; Gilmore, B.F.; Miller, Arne

    2014-01-01

    or anti-microbial additives. The work outlined in this paper investigates the use of low energy electron beam irradiation to surface modify polyhydroxyacid samples incorporating beta tricalcium phosphate (β-TCP). This work uniquely demonstrates that surface modification of bioresorbable polymers through...... electron beam irradiation allows for the early release of incorporated agents such as bioactive additives. Samples were e-beam irradiated at an energy of 125 keV and doses of either 150 kGy or 500 kGy. Irradiated and non-irradiated samples were degraded in phosphate buffered saline (PBS), to simulate...... bioresorption, followed by characterisation. The results show that low energy e-beam irradiation enhances surface hydrolytic degradation in comparison to bulk and furthermore allows for earlier release of incorporated calcium via dissolution into the surrounding medium....

  7. Glass fibres reinforced polyester composites degradation monitoring by surface analysis

    Energy Technology Data Exchange (ETDEWEB)

    Croitoru, Catalin [“Transilvania” University of Brasov, Materials Engineering and Welding Department, Eroilor 29 Str., 500036 Brasov (Romania); Patachia, Silvia, E-mail: st.patachia@unitbv.ro [“Transilvania” University of Brasov, Product Design Environment and Mechatronics Department, Eroilor 29 Str., 500036 Brasov (Romania); Papancea, Adina [“Transilvania” University of Brasov, Product Design Environment and Mechatronics Department, Eroilor 29 Str., 500036 Brasov (Romania); Baltes, Liana; Tierean, Mircea [“Transilvania” University of Brasov, Materials Engineering and Welding Department, Eroilor 29 Str., 500036 Brasov (Romania)

    2015-12-15

    Highlights: • Glass fibre-reinforced polyester composites surface analysis by photographic method. • The composites are submitted to accelerated ageing by UV irradiation at 254 nm. • The UV irradiation promotes differences in the surface chemistry of the composites. • MB dye is differently adsorbed on surfaces with different degradation degrees. • Good correlation between the colouring degree and surface chemistry. - Abstract: The paper presents a novel method for quantification of the modifications that occur on the surface of different types of gel-coated glass fibre-reinforced polyester composites under artificial UV-ageing at 254 nm. The method implies the adsorption of an ionic dye, namely methylene blue, on the UV-aged composite, and computing the CIELab colour space parameters from the photographic image of the coloured composite's surface. The method significantly enhances the colour differences between the irradiated composites and the reference, in contrast with the non-coloured ones. The colour modifications that occur represent a good indicative of the surface degradation, alteration of surface hydrophily and roughness of the composite and are in good correlation with the ATR-FTIR spectroscopy and optical microscopy results. The proposed method is easier, faster and cheaper than the traditional ones.

  8. Metagenomics Reveals Microbial Community Composition And Function With Depth In Arctic Permafrost Cores

    Science.gov (United States)

    Jansson, J.; Tas, N.; Wu, Y.; Ulrich, C.; Kneafsey, T. J.; Torn, M. S.; Hubbard, S. S.; Chakraborty, R.; Graham, D. E.; Wullschleger, S. D.

    2013-12-01

    The Arctic is one of the most climatically sensitive regions on Earth and current surveys show that permafrost degradation is widespread in arctic soils. Biogeochemical feedbacks of permafrost thaw are expected to be dominated by the release of currently stored carbon back into the atmosphere as CO2 and CH4. Understanding the dynamics of C release from permafrost requires assessment of microbial functions from different soil compartments. To this end, as part of the Next Generation Ecosystem Experiment in the Arctic, we collected two replicate permafrost cores (1m and 3m deep) from a transitional polygon near Barrow, AK. At this location, permafrost starts from 0.5m in depth and is characterized by variable ice content and higher pH than surface soils. Prior to sectioning, the cores were CT-scanned to determine the physical heterogeneity throughout the cores. In addition to detailed geochemical characterization, we used Illumina MiSeq technology to sequence 16SrRNA genes throughout the depths of the cores at 1 cm intervals. Selected depths were also chosen for metagenome sequencing of total DNA (including phylogenetic and functional genes) using the Illumina HiSeq platform. The 16S rRNA gene sequence data revealed that the microbial community composition and diversity changed dramatically with depth. The microbial diversity decreased sharply below the first few centimeters of the permafrost and then gradually increased in deeper layers. Based on the metagenome sequence data, the permafrost microbial communities were found to contain members with a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. The surface active layers had more representatives of Verrucomicrobia (potential methane oxidizers) whereas the deep permafrost layers were dominated by several different species of Actinobacteria. The latter are known to have a diverse metabolic capability and are able to adapt to stress by entering a dormant yet

  9. Impact of dynamic vegetation phenology on the simulated pan-Arctic land surface state

    Science.gov (United States)

    Teufel, Bernardo; Sushama, Laxmi; Arora, Vivek K.; Verseghy, Diana

    2018-03-01

    The pan-Arctic land surface is undergoing rapid changes in a warming climate, with near-surface permafrost projected to degrade significantly during the twenty-first century. Vegetation-related feedbacks have the potential to influence the rate of degradation of permafrost. In this study, the impact of dynamic phenology on the pan-Arctic land surface state, particularly near-surface permafrost, for the 1961-2100 period, is assessed by comparing two simulations of the Canadian Land Surface Scheme (CLASS)—one with dynamic phenology, modelled using the Canadian Terrestrial Ecosystem Model (CTEM), and the other with prescribed phenology. These simulations are forced by atmospheric data from a transient climate change simulation of the 5th generation Canadian Regional Climate Model (CRCM5) for the Representative Concentration Pathway 8.5 (RCP8.5). Comparison of the CLASS coupled to CTEM simulation to available observational estimates of plant area index, spatial distribution of permafrost and active layer thickness suggests that the model captures reasonably well the overall distribution of vegetation and permafrost. It is shown that the most important impact of dynamic phenology on the land surface occurs through albedo and it is demonstrated for the first time that vegetation control on albedo during late spring and early summer has the highest potential to impact the degradation of permafrost. While both simulations show extensive near-surface permafrost degradation by the end of the twenty-first century, the strong projected response of vegetation to climate warming and increasing CO2 concentrations in the coupled simulation results in accelerated permafrost degradation in the northernmost continuous permafrost regions.

  10. Why Permafrost Is Thawing, Not Melting

    Science.gov (United States)

    Grosse, Guido; Romanovsky, Vladimir; Nelson, Frederick E.; Brown, Jerry; Lewkowicz, Antoni G.

    2010-03-01

    As global climate change is becoming an increasingly important political and social issue, it is essential for the cryospheric and global change research communities to speak with a single voice when using basic terminology to communicate research results and describe underlying physical processes. Experienced science communicators have highlighted the importance of using the correct terms to communicate research results to the media and general public [e.g., Akasofu, 2008; Hassol, 2008]. The consequences of scientists using improper terminology are at best oversimplification, but they more likely involve misunderstandings of the facts by the public. A glaring example of scientifically incorrect terminology appearing frequently in scientific and public communication relates to reports on the degradation of permafrost. Numerous research papers have appeared in recent years, broadly echoed in the news media, describing the “melting of permafrost,” its effects in the Arctic, and its feedbacks on climate through the carbon cycle. Although permafrost researchers have attempted to distinguish between the appropriate term “permafrost thawing” and the erroneous “permafrost melting” [e.g., van Everdingen, 2005; French, 2002], the latter is still used widely. A Web-based search using the phrase “permafrost melting” reveals hundreds of occurrences, many from highly regarded news and scientific organizations, including Reuters, New Scientist, ABC, The Guardian, Discovery News, Smithsonian magazine, the National Science Foundation, and others.

  11. Irradiation of bioresorbable biomaterials for controlled surface degradation

    Science.gov (United States)

    Simpson, M.; Gilmore, B. F.; Miller, A.; Helt-Hansen, J.; Buchanan, F. J.

    2014-01-01

    Bioresorbable polymers increasingly are the materials of choice for implantable orthopaedic fixation devices. Controlled degradation of these polymers is vital for preservation of mechanical properties during tissue repair and controlled release of incorporated agents such as osteoconductive or anti-microbial additives. The work outlined in this paper investigates the use of low energy electron beam irradiation to surface modify polyhydroxyacid samples incorporating beta tricalcium phosphate (β-TCP). This work uniquely demonstrates that surface modification of bioresorbable polymers through electron beam irradiation allows for the early release of incorporated agents such as bioactive additives. Samples were e-beam irradiated at an energy of 125 keV and doses of either 150 kGy or 500 kGy. Irradiated and non-irradiated samples were degraded in phosphate buffered saline (PBS), to simulate bioresorption, followed by characterisation. The results show that low energy e-beam irradiation enhances surface hydrolytic degradation in comparison to bulk and furthermore allows for earlier release of incorporated calcium via dissolution into the surrounding medium.

  12. The subcatchment- and catchment-scale hydrology of a boreal headwater peatland complex with sporadic permafrost.

    Science.gov (United States)

    Sonnentag, O.; Helbig, M.; Connon, R.; Hould Gosselin, G.; Ryu, Y.; Karoline, W.; Hanisch, J.; Moore, T. R.; Quinton, W. L.

    2017-12-01

    The permafrost region of the Northern Hemisphere has been experiencing twice the rate of climate warming compared to the rest of the Earth, resulting in the degradation of the cryosphere. A large portion of the high-latitude boreal forests of northwestern Canada grows on low-lying organic-rich lands with relative warm and thin isolated, sporadic and discontinuous permafrost. Along this southern limit of permafrost, increasingly warmer temperatures have caused widespread permafrost thaw leading to land cover changes at unprecedented rates. A prominent change includes wetland expansion at the expense of Picea mariana (black spruce)-dominated forest due to ground surface subsidence caused by the thawing of ice-rich permafrost leading to collapsing peat plateaus. Recent conceptual advances have provided important new insights into high-latitude boreal forest hydrology. However, refined quantitative understanding of the mechanisms behind water storage and movement at subcatchment and catchment scales is needed from a water resources management perspective. Here we combine multi-year daily runoff measurements with spatially explicit estimates of evapotranspiration, modelled with the Breathing Earth System Simulator, to characterize the monthly growing season catchment scale ( 150 km2) hydrological response of a boreal headwater peatland complex with sporadic permafrost in the southern Northwest Territories. The corresponding water budget components at subcatchment scale ( 0.1 km2) were obtained from concurrent cutthroat flume runoff and eddy covariance evapotranspiration measurements. The highly significant linear relationships for runoff (r2=0.64) and evapotranspiration (r2=0.75) between subcatchment and catchment scales suggest that the mineral upland-dominated downstream portion of the catchment acts hydrologically similar to the headwater portion dominated by boreal peatland complexes. Breakpoint analysis in combination with moving window statistics on multi

  13. Numerical modeling of permafrost dynamics in Alaska using a high spatial resolution dataset

    Directory of Open Access Journals (Sweden)

    E. E. Jafarov

    2012-06-01

    Full Text Available Climate projections for the 21st century indicate that there could be a pronounced warming and permafrost degradation in the Arctic and sub-Arctic regions. Climate warming is likely to cause permafrost thawing with subsequent effects on surface albedo, hydrology, soil organic matter storage and greenhouse gas emissions.

    To assess possible changes in the permafrost thermal state and active layer thickness, we implemented the GIPL2-MPI transient numerical model for the entire Alaska permafrost domain. The model input parameters are spatial datasets of mean monthly air temperature and precipitation, prescribed thermal properties of the multilayered soil column, and water content that are specific for each soil class and geographical location. As a climate forcing, we used the composite of five IPCC Global Circulation Models that has been downscaled to 2 by 2 km spatial resolution by Scenarios Network for Alaska Planning (SNAP group.

    In this paper, we present the modeling results based on input of a five-model composite with A1B carbon emission scenario. The model has been calibrated according to the annual borehole temperature measurements for the State of Alaska. We also performed more detailed calibration for fifteen shallow borehole stations where high quality data are available on daily basis. To validate the model performance, we compared simulated active layer thicknesses with observed data from Circumpolar Active Layer Monitoring (CALM stations. The calibrated model was used to address possible ground temperature changes for the 21st century. The model simulation results show widespread permafrost degradation in Alaska could begin between 2040–2099 within the vast area southward from the Brooks Range, except for the high altitude regions of the Alaska Range and Wrangell Mountains.

  14. Soil CO2 production in upland tundra where permafrost is thawing

    Science.gov (United States)

    Hanna Lee; Edward A.G. Schuur; Jason G. Vogel

    2010-01-01

    Permafrost soils store nearly half of global soil carbon (C), and therefore permafrost thawing could lead to large amounts of greenhouse gas emissions via decomposition of soil organic matter. When ice-rich permafrost thaws, it creates a localized surface subsidence called thermokarst terrain, which changes the soil microenvironment. We used soil profile CO2...

  15. Development of capability for microtopography-resolving simulations of hydrologic processes in permafrost affected regions

    Science.gov (United States)

    Painter, S.; Moulton, J. D.; Berndt, M.; Coon, E.; Garimella, R.; Lewis, K. C.; Manzini, G.; Mishra, P.; Travis, B. J.; Wilson, C. J.

    2012-12-01

    The frozen soils of the Arctic and subarctic regions contain vast amounts of stored organic carbon. This carbon is vulnerable to release to the atmosphere as temperatures warm and permafrost degrades. Understanding the response of the subsurface and surface hydrologic system to degrading permafrost is key to understanding the rate, timing, and chemical form of potential carbon releases to the atmosphere. Simulating the hydrologic system in degrading permafrost regions is challenging because of the potential for topographic evolution and associated drainage network reorganization as permafrost thaws and massive ground ice melts. The critical process models required for simulating hydrology include subsurface thermal hydrology of freezing/thawing soils, thermal processes within ice wedges, mechanical deformation processes, overland flow, and surface energy balances including snow dynamics. A new simulation tool, the Arctic Terrestrial Simulator (ATS), is being developed to simulate these coupled processes. The computational infrastructure must accommodate fully unstructured grids that track evolving topography, allow accurate solutions on distorted grids, provide robust and efficient solutions on highly parallel computer architectures, and enable flexibility in the strategies for coupling among the various processes. The ATS is based on Amanzi (Moulton et al. 2012), an object-oriented multi-process simulator written in C++ that provides much of the necessary computational infrastructure. Status and plans for the ATS including major hydrologic process models and validation strategies will be presented. Highly parallel simulations of overland flow using high-resolution digital elevation maps of polygonal patterned ground landscapes demonstrate the feasibility of the approach. Simulations coupling three-phase subsurface thermal hydrology with a simple thaw-induced subsidence model illustrate the strong feedbacks among the processes. D. Moulton, M. Berndt, M. Day, J

  16. An improved model for soil surface temperature from air temperature in permafrost regions of Qinghai-Xizang (Tibet) Plateau of China

    Science.gov (United States)

    Hu, Guojie; Wu, Xiaodong; Zhao, Lin; Li, Ren; Wu, Tonghua; Xie, Changwei; Pang, Qiangqiang; Cheng, Guodong

    2017-08-01

    Soil temperature plays a key role in hydro-thermal processes in environments and is a critical variable linking surface structure to soil processes. There is a need for more accurate temperature simulation models, particularly in Qinghai-Xizang (Tibet) Plateau (QXP). In this study, a model was developed for the simulation of hourly soil surface temperatures with air temperatures. The model incorporated the thermal properties of the soil, vegetation cover, solar radiation, and water flux density and utilized field data collected from Qinghai-Xizang (Tibet) Plateau (QXP). The model was used to simulate the thermal regime at soil depths of 5 cm, 10 cm and 20 cm and results were compared with those from previous models and with experimental measurements of ground temperature at two different locations. The analysis showed that the newly developed model provided better estimates of observed field temperatures, with an average mean absolute error (MAE), root mean square error (RMSE), and the normalized standard error (NSEE) of 1.17 °C, 1.30 °C and 13.84 %, 0.41 °C, 0.49 °C and 5.45 %, 0.13 °C, 0.18 °C and 2.23 % at 5 cm, 10 cm and 20 cm depths, respectively. These findings provide a useful reference for simulating soil temperature and may be incorporated into other ecosystem models requiring soil temperature as an input variable for modeling permafrost changes under global warming.

  17. A new map of permafrost distribution on the Tibetan Plateau

    Science.gov (United States)

    Zou, Defu; Zhao, Lin; Sheng, Yu; Chen, Ji; Hu, Guojie; Wu, Tonghua; Wu, Jichun; Xie, Changwei; Wu, Xiaodong; Pang, Qiangqiang; Wang, Wu; Du, Erji; Li, Wangping; Liu, Guangyue; Li, Jing; Qin, Yanhui; Qiao, Yongping; Wang, Zhiwei; Shi, Jianzong; Cheng, Guodong

    2017-11-01

    The Tibetan Plateau (TP) has the largest areas of permafrost terrain in the mid- and low-latitude regions of the world. Some permafrost distribution maps have been compiled but, due to limited data sources, ambiguous criteria, inadequate validation, and deficiency of high-quality spatial data sets, there is high uncertainty in the mapping of the permafrost distribution on the TP. We generated a new permafrost map based on freezing and thawing indices from modified Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperatures (LSTs) and validated this map using various ground-based data sets. The soil thermal properties of five soil types across the TP were estimated according to an empirical equation and soil properties (moisture content and bulk density). The temperature at the top of permafrost (TTOP) model was applied to simulate the permafrost distribution. Permafrost, seasonally frozen ground, and unfrozen ground covered areas of 1.06 × 106 km2 (0.97-1.15 × 106 km2, 90 % confidence interval) (40 %), 1.46 × 106 (56 %), and 0.03 × 106 km2 (1 %), respectively, excluding glaciers and lakes. Ground-based observations of the permafrost distribution across the five investigated regions (IRs, located in the transition zones of the permafrost and seasonally frozen ground) and three highway transects (across the entire permafrost regions from north to south) were used to validate the model. Validation results showed that the kappa coefficient varied from 0.38 to 0.78 with a mean of 0.57 for the five IRs and 0.62 to 0.74 with a mean of 0.68 within the three transects. Compared with earlier studies, the TTOP modelling results show greater accuracy. The results provide more detailed information on the permafrost distribution and basic data for use in future research on the Tibetan Plateau permafrost.

  18. Ionospheric Correction in Using ALOS PALSAR InSAR Data for Monitoring Permafrost Subsidence associated with an Arctic Tundra Fire

    Science.gov (United States)

    Liao, H.; Meyer, F. J.; Liu, L.

    2017-12-01

    Tundra fires have important ecological impacts on vegetation succession, carbon cycling, and permafrost dynamics. Recent research has demonstrated that SAR Interferometry (InSAR) is a useful tool for quantifying surface subsidence caused by permafrost degradation and tundra fires. Many of these studies have relied on L-band SAR data due to its ability to remain relatively high coherence in the changing Arctic environment. L-band SAR data, however, are susceptive to ionospheric effects. Traditionally, permafrost-related InSAR studies dealt with ionospheric artifacts by either throwing away ionosphere-contaminated data or by fitting and removing low-order polynomial surfaces from affected images. Discarding data samples is always luxurious and risky, as the number of SAR images is limited and the incurred reduction of temporal sampling might hinder the retrieval of important short-term dynamics in active layer and permafrost. Baseline fitting relies on the assumption that ionospheric signals large spatial scales, an assumption that is often violated in polar regions. To improve upon this situation, we propose the integration of the split-spectrum ionospheric correction technique into permafrost-related InSAR processing workflows. We demonstrate its performance for correcting L-band SAR data in permafrost zones. For the Anaktuvuk River fire area, Alaska, 6 out of 15 ALOS-1 PALSAR scenes used by Liu et al. 2014 were found to be contaminated by ionospheric signals. We extracted the ionospheric phase screens for all contaminated data. We derive their power spectra and provide information on the typical magnitudes and spatial structures of identified phase screens. With the ionosphere corrected data we revisit a model that was developed by Liu et.al (2014) to estimate pre-fire and post-fire thaw-season subsidence for the Anaktuvuk River fire region. We will demonstrate that for our area of interest ionospheric correction leads to improvements of the InSAR-based permafrost

  19. Biodegradability of dissolved organic carbon in permafrost soils and aquatic systems: a meta-analysis

    Science.gov (United States)

    Jorien E. Vonk,; Tank, Suzanne E.; Paul J. Mann,; Robert G.M. Spencer,; Treat, Claire C.; Striegl, Robert G.; Benjamin W. Abbott,; Wickland, Kimberly P.

    2015-01-01

    in the summer, as well as decreasing hydrologic connectivity between soils and surface water as the thaw season progresses. Our results suggest that future climate warming-induced shifts of continuous permafrost into discontinuous permafrost regions could affect the degradation potential of thaw-released DOC, the amount of BDOC, as well as its variability throughout the Arctic summer. We lastly recommend a standardized BDOC protocol to facilitate the comparison of future work and improve our knowledge of processing and transport of DOC in a changing Arctic.

  20. Permafrost and urban Development in Norilsk Russia.

    Science.gov (United States)

    Shiklomanov, N. I.; Streletskiy, D. A.; Grebenets, V. I.

    2017-12-01

    The city of Norilsk was established in 1935 as a GULAG mining and metallurgy work camp to explore the rich deposits of non-ferrous metals. By the 1989, the population of Norilsk reached 179,757 people. Two additional cities were developed in proximity to Norilsk in the 1960s-1980s: Talnakh (1989 population 65,710); and Kaerkan (1989 population 29,824) making the Norilsk region a major Arctic metropolis. While such rapid growth is not unusual for developing industrial cities, the geographic location makes Norilsk rather unique among world urban centers. It was built in Central Siberia at 69°51' N latitude (above the Arctic Circle), in region characterized by harsh subarctic climate (mean annual temperature around -10 oC), over forest tundra/tundra transitional landscapes underlined by perennially frozen ground (permafrost). Throughout its existence, the Norilsk region was highly isolated: it is not connected to Russian road and railroad systems. The harsh environmental conditions provided significant and rather unique challenges to Norilsk development. Specifically, the presence of ice-rich permafrost imposed restrictions on application of standard urban planning and engineering practices. This presentation analyzes the history of permafrost construction in Norilsk. It shows how though initial trial and errors, a set of guiding principles and engineering methods of construction on permafrost were developed allowing a rapid urbanization of the area during the 1960-1980s. However, despite significant advances in permafrost engineering, the pronounced permafrost degradation has become evident in Norilsk by the mid 1980s and has accelerated rapidly since the mid 1990s resulting in widespread deformation of buildings. Climatic changes are frequently identified as a major cause of accelerated deterioration of infrastructure build on permafrost. However, we argue that other factors, including the complexity of interactions between deferent components of urban

  1. Permafrost dynamics in 20th and 21st centuries along the east-Siberian and Alaskan transects

    Science.gov (United States)

    Sazonova, Tatiana Sergeevna

    High latitude ecosystems where the mean annual ground surface temperature is around or below 0°C are highly sensitive to global warming. This is largely because these regions contain vast areas of permafrost, which will begin to degrade when the mean annual ground temperatures will rise above 0°C. The Alaskan and East Siberian transects, centered on the 155° WL and 135° EL, were chosen for evaluation of permafrost---atmosphere interactions. The analysis of measured data shows a significant increase in air and ground temperatures that started from the late 1960s within both these transects and the magnitude of this increase is from 0.2 to 0.5°C per decade. This trend is comparable to trends predicted by majority of global warming scenarios. A simple and accurate model for evaluating the permafrost dynamics was developed in Geophysical Institute Permafrost Lab (GIPL). The GIPL model is a fusion of the modified Kudryavtsev's approach, which is a set of analytical formulas for active layer thickness (ALT) and mean annual ground temperature (MAGT) calculations, with the Geographic Information System (GIS). The evaluation of the GIPL performance showed that when applied to long-term (decadal or longer time scale) averages, this model achieves an accuracy of +/-0.2--0.4°C for the mean annual ground temperatures and +0.1--0.3 m for the active layer thickness calculations. The GIPL model was used for the hindcast of the permafrost dynamics in the 20th century, using a combination of observationally-based and simulated monthly grids of surface air temperature. The results showed that during the 20th century there were a number of relatively cold and warm periods. These climatic variations produced 1 to 3°C changes in MAGT and up to 1 m in the ALT. The forecast for the period of 2000--2100 was performed using climatic parameters from six Global Climate Models provided by Arctic Climate Impact Assessment program. The results showed that by the end of 21st century mean

  2. Estimation of the permafrost stability on the East Arctic shelf under the extreme climate warming scenario for the XXI century

    Directory of Open Access Journals (Sweden)

    V. V. Malakhova

    2016-01-01

    Full Text Available A state of permafrost in the Arctic is the key to understanding whether methane, stored in the permafrost related gas hydrate, can release into the atmosphere. The global warming can lead to destabilization of the submarine permafrost and, thus, cause the methane releasing into the water. The near-bottom water temperature plays a significant role in the current state of the submarine permafrost, because it specifies a depth of thawing of the permafrost. We have numerically simulated evolution of the submarine permafrost on the East Siberia Arctic shelf for the last glacial cycle. In order to estimate a possible state and stability of the submarine permafrost we did carry out a numerical run based on the ICMMG SB RAS the coupled ocean-ice and submarine permafrost model. For the atmosphere forcing, the GFDL CM3 coupled climate model output, simulated under the scenario RCP8.5, was used. The scenario RCP8.5 was used since it predicted the strongest warming by the end of the 21-st century. The GFDL СM3 model, predicting the most pronounced Arctic warming, was also used in order to put the tentative upper boundary on the submarine permafrost degradation in this century.The results obtained show that the offshore permafrost exists across the vast East Siberia shelf. This permafrost occurs continuously but its thickness changes. Thickness of the permafrost within the most part of the East Siberia shelf is estimated 470–590 m when the value of 60 W/m2 was used for the geothermal flux. Our results reveal a certain rising of the bottom layer temperature on the shelf and subsequent penetration of a heat flux into the sediments. However, our results show that even the extreme warming is not sufficient to destabilize the submarine permafrost on the shelf of both, the Laptev Sea and the East Siberian Sea. By the end of the 21st century, upper boundary of the permafrost deepens by value from 1 to 11 m only due to the thermal effects, and by 5–10 m in

  3. Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States); Schlosser, Courtney [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Melillo, Jerry [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Walter, Katey [Univ. of Alaska, Fairbanks, AK (United States)

    2015-09-15

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  4. Influences of Moisture Regimes and Functional Plant Types on Nutrient Cycling in Permafrost Regions

    Science.gov (United States)

    McCaully, R. E.; Arendt, C. A.; Newman, B. D.; Heikoop, J. M.; Wilson, C. J.; Sevanto, S.; Wales, N. A.; Wullschleger, S.

    2017-12-01

    In the permafrost-dominated Arctic, climatic feedbacks exist between permafrost, soil moisture, functional plant type and presence of nutrients. Functional plant types present within the Arctic regulate and respond to changes in hydrologic regimes and nutrient cycling. Specifically, alders are a member of the birch family that use root nodules to fix nitrogen, which is a limiting nutrient strongly linked to fertilizing Arctic ecosystems. Previous investigations in the Seward Peninsula, AK show elevated presence of nitrate within and downslope of alder patches in degraded permafrost systems, with concentrations an order of magnitude greater than that of nitrate measured above these patches. Further observations within these degraded permafrost systems are crucial to assess whether alders are drivers of, or merely respond to, nitrate fluxes. In addition to vegetative feedbacks with nitrate supply, previous studies have also linked low moisture content to high nitrate production. Within discontinuous permafrost regions, the absence of permafrost creates well-drained regions with unsaturated soils whereas the presence of permafrost limits vertical drainage of soil-pore water creating elevated soil moisture content, which likely corresponds to lower nitrate concentrations. We investigate these feedbacks further in the Seward Peninsula, AK, through research supported by the United States Department of Energy Next Generation Ecosystem Experiment (NGEE) - Arctic. Using soil moisture and thaw depth as proxies to determine the extent of permafrost degradation, we identify areas of discontinuous permafrost over a heterogeneous landscape and collect co-located soilwater chemistry samples to highlight the complex relationships that exist between alder patches, soil moisture regimes, the presence of permafrost and available nitrate supply. Understanding the role of nitrogen in degrading permafrost systems, in the context of both vegetation present and soil moisture, is crucial

  5. Land cover change in the zone of sporadic permafrost causes shift in landscape-scale turbulent energy fluxes

    Science.gov (United States)

    Helbig, M.; Wischnewski, K.; Kljun, N.; Chasmer, L.; Quinton, W. L.; Detto, M.; Sonnentag, O.

    2015-12-01

    current heterogeneous to a homogeneous bog landscape could lead to a decrease in the maximum PBL height by about 700 m and to a decrease in regional Ta by 1 to 2 K. Our results show clearly that permafrost degradation and forest cover shifts will affect local and regional surface energy balances in the boreal zone and could represent important modifiers of future climates.

  6. Spatiotemporal Interaction of Near-Surface Soil Moisture Content and Frost Table Depth in a Discontinuous Permafrost Environment

    Science.gov (United States)

    Guan, X.; Spence, C.; Westbrook, C. J.

    2009-05-01

    The ubiquitous presence of frozen ground in cold regions creates a unique dynamic boundary issue for subsurface water movement and storage. We examined the relationship between ground thaw and spatiotemporal soil moisture patterns at three sites (peatland, wetland and valley) near Yellowknife NT. Thaw depth and near-surface soil moisture were measured along a systematic grid at each site. Energy and water budgets were computed for each site to explain the soil moisture patterns. At the peatland, overall soil moisture decreased through the summer and became more spatially homogeneous with deepened thaw, increased subsurface storage capacity, and drying from evapotranspiration. In the peatland and wetland, accumulated water in depressions maintained soils at higher soil moistures for a longer duration than the hummock tops. The depressions had deeper frost tables than the drier hummock tops because the organic mats covering the hummocks insulated the ground and retarded ground thaw. The wettest soils were often locations of deepest thaw depth due to surface ponding and the transfer of latent heat accompanying surface runoff from upslopes. For example, the 3.3 ha wetland received 3.08x105 m3 of surface inflow from a lake with 2.32 kJm-2 of convective heat available to be transferred into the frozen ground over the study period. Soil moisture patterns also revealed preferential surface and subsurface flow routes. The findings indicate that the presence of frozen ground and differential thawing have a diverse and dynamic relationship with near-surface soil moisture content. When the impermeable boundary is dynamic, and controlled by water and energy fluxes, thicker soil layers are associated with higher moisture. This contrasts findings from temperate regions with a fixed impermeable boundary which show that surface soil moisture content can be lower in areas with thick soil.

  7. Permafrost as an additional driving factor for the extreme fire event in the boreal Baikal region in 2003

    Science.gov (United States)

    Forkel, M.; Thonicke, K.; Beer, C.; Cramer, W.; Bartalev, S.; Schmullius, C.

    2012-04-01

    Wildfires are a natural and important element in the functioning of boreal forests. However, in some years, fires with extreme spread and severity occur. Such severe fires degrade the forest, affect human values, emit huge amount of carbon and aerosols and alter the land surface albedo. Usually, wind, slope, and dry conditions have been recognized as factors determining fire spread. In the Baikal region, 127,000 km2 burned in 2003, while the annual average burned area is approx. 8100 km2. In average years, 16% of the burned area occurred in the continuous permafrost zone but in 2003, 33% of these burned areas coincide with the existence of permanently frozen grounds. Permafrost and the associated upper active layer, which thaws during summer and refreezes during winter, is an important supply for soil moisture in boreal ecosystems. This leads to the question if permafrost hydrology is a potential additional driving factor for extreme fire events in boreal forests. Using temperature and precipitation data, we calculated the Nesterov index as indicator for fire weather conditions. Further, we used satellite observations of burned area and surface moisture, a digital elevation model, a land cover and a permafrost map to evaluate drivers for the temporal dynamic and spatial variability of surface moisture conditions and burned area in spring 2003. On the basis of time series decomposition, we separated the effect of drivers for fire activity on different time scales. We next computed cross-correlations to identify potential time lags between weather conditions, surface moisture and fire activity. Finally, we assessed the predictive capability of different combinations of driving variables for surface moisture conditions and burned area using multivariate spatial-temporal regression models. The results from this study demonstrate that permafrost in larch-dominated ecosystems regulates the inter-annual variability of surface moisture and thus increases the inter

  8. Quality and Distribution of Frozen Organic Matter (Old, Deep, Fossil Carbon) in Siberian Permafrost

    Science.gov (United States)

    Schirrmeister, Lutz; Strauss, Jens; Wetterich, Sebastian; Grosse, Guido; Overduin, Pier Paul

    2013-04-01

    Permafrost deposits constitute a large organic carbon (OC) pool vulnerable to degradation and potential carbon release due to global warming. Permafrost sections along coastal and river bank exposures and subsea cores in northeastern Siberia were studied for organic matter (OM) characteristics and ice content. OM stored in Quaternary permafrost grew, accumulated, froze, partly decomposed, and refroze under different periglacial environments, reflected in specific biogeochemical and cryolithological features. For the studied individual strata (Saalian ice-rich deposits, Pre-Eemian floodplain, Eemian lake deposits, Early to Middle Weichselian fluvial deposits, Middle Weichselian Yedoma, Late Weichselian Yedoma , Taberites, Holocene cover, Holocene thermokarst, Holocene thermoerosional valley and submerged lagoon and fluvial deposits) OM accumulation, preservation, and distribution are strongly linked to a broad variety of paleoenvironmental factors and specific surface and subsurface conditions before inclusion of OM into the permafrost. OM in permafrost includes twigs, leaves, peat, grass roots, plant detritus, and particulate and dissolved OM. The vertical distribution of total OC (TOC) in exposures varies from 0.1 wt % of the dry sediment in fluvial deposits to 45 wt % in Holocene peats. High TOC, high C/N, and low d13C reflect less decomposed OM accumulated under wet, anaerobic soil conditions characteristic of interglacial and interstadial periods. Glacial and stadial periods are characterized by less variable, low TOC, low C/N, and high d13C values indicating stable environments with reduced bioproductivity and stronger OM decomposition under dryer, aerobic soil conditions. Based on TOC data and updated information on bulk densities, we estimate average OC inventories for different stratigraphic units in northeastern Siberia, ranging from 7 kg C/m³ for Early Weichselian fluvial deposits, to 33 kg C/m³ for Middle Weichselian Yedoma deposits, to 75 kg C/m³ for

  9. Subsidence from an artificial permafrost warming experiment.

    Science.gov (United States)

    Gelvin, A.; Wagner, A. M.; Lindsey, N.; Dou, S.; Martin, E. R.; Ekblaw, I.; Ulrich, C.; James, S. R.; Freifeld, B. M.; Daley, T. M.; Saari, S.; Ajo Franklin, J. B.

    2017-12-01

    Using fiber optic sensing technologies (seismic, strain, and temperature) we installed a geophysical detection system to predict thaw subsidence in Fairbanks, Alaska, United States. Approximately 5 km of fiber optic was buried in shallow trenches (20 cm depth), in an area with discontinuous permafrost, where the top of the permafrost is approximately 4 - 4.5m below the surface. The thaw subsidence was enforced by 122 60-Watt vertical heaters installed over a 140 m2 area where seismic, strain, and temperature were continuously monitored throughout the length of the fiber. Several vertical thermistor strings were also recording ground temperatures to a depth of 10 m in parallel to the fiber optic to verify the measurements collected from the fiber optic cable. GPS, Electronic Distance Measurement (EDM) Traditional and LiDAR (Light and Detection and Ranging) scanning were used to investigate the surface subsidence. The heaters were operating for approximately a three month period starting in August, 2016. During the heating process the soil temperatures at the heater element increased from 3.5 to 45 °C at a depth of 3 - 4 m. It took approximately 7 months for the temperature at the heater elements to recover to their initial temperature. The depth to the permafrost table was deepened by about 1 m during the heating process. By the end of the active heating, the surface had subsided approximately 8 cm in the heating section where permafrost was closest to the surface. This was conclusively confirmed with GPS, EDM, and LiDAR. An additional LiDAR survey was performed about seven months after the heaters were turned off (in May 2017). A total subsidence of approximately 20 cm was measured by the end of the passive heating process. This project successfully demonstrates that this is a viable approach for simulating both deep permafrost thaw and the resulting surface subsidence.

  10. Permafrost: An International Approach to 21th Century Challenges

    Science.gov (United States)

    Brown, J.

    2003-12-01

    Whereas glaciers are easily discernible to the human eye and satellites, permafrost terrains and their physical components are not easily detected from the surface without supplemental knowledge and measurements. In the Northern Hemisphere, approximately 17 million km2 of exposed land contains some extent of permafrost or ground that remains frozen for more than two years. The vast majority, or 11 million km2, of permafrost terrain has temperatures of 5° C or below, with perennially frozen ground underlying essentially all ground surfaces to considerable depths. Permafrost in the remaining regions, including mid-latitude mountains, is both warmer and is spatially variable (discontinuous). As climate warms the uppermost permafrost is subjected to increase thaw with resulting ground subsidence, accelerated erosion, and related biogeochemical modifications. The challenging questions to geocryologists, modelers and the public relate to the rate of change and the spatial variability of the projected thaw, particularly in the warmer zones where actual areal and subareal distribution of permafrost is poorly known. An international network of active layer measurements and borehole sites now exists under the Global Climate Observing System (GCOS), but requires additional sites for representative coverage. This Global Terrestrial Network for Permafrost (GTN-P) is coordinated by the 24-member, International Permafrost Association. At the Eighth International Conference on Permafrost (ICOP) in Zurich in July 2003, the IPA Council agreed on the scope of new activities for the next five years, many of which will be undertaken in cooperation with other international organizations (e.g. WCRP/CliC; ICSI, IASC, SCAR, IGU, IUGS). Examples of the activities of the IPA Working Groups are: 1. Antarctic Permafrost and Periglacial Environments (active layer processes, maps, database). 2. Coastal and Offshore Permafrost (sediment and organic transfers, subsea permafrost dynamics). 3

  11. Transient thermal modeling of permafrost conditions in Southern Norway

    Directory of Open Access Journals (Sweden)

    S. Westermann

    2013-04-01

    Full Text Available Thermal modeling is a powerful tool to infer the temperature regime of the ground in permafrost areas. We present a transient permafrost model, CryoGrid 2, that calculates ground temperatures according to conductive heat transfer in the soil and in the snowpack. CryoGrid 2 is forced by operational air temperature and snow-depth products for potential permafrost areas in Southern Norway for the period 1958 to 2009 at 1 km2 spatial resolution. In total, an area of about 80 000 km2 is covered. The model results are validated against borehole temperatures, permafrost probability maps from "bottom temperature of snow" measurements and inventories of landforms indicative of permafrost occurrence. The validation demonstrates that CryoGrid 2 can reproduce the observed lower permafrost limit to within 100 m at all validation sites, while the agreement between simulated and measured borehole temperatures is within 1 K for most sites. The number of grid cells with simulated permafrost does not change significantly between the 1960s and 1990s. In the 2000s, a significant reduction of about 40% of the area with average 2 m ground temperatures below 0 °C is found, which mostly corresponds to degrading permafrost with still negative temperatures in deeper ground layers. The thermal conductivity of the snow is the largest source of uncertainty in CryoGrid 2, strongly affecting the simulated permafrost area. Finally, the prospects of employing CryoGrid 2 as an operational soil-temperature product for Norway are discussed.

  12. The microbial ecology of permafrost

    DEFF Research Database (Denmark)

    Jansson, Janet; Tas, Neslihan

    2014-01-01

    Permafrost constitutes a major portion of the terrestrial cryosphere of the Earth and is a unique ecological niche for cold-adapted microorganisms. There is a relatively high microbial diversity in permafrost, although there is some variation in community composition across different permafrost......-gas emissions. This Review describes new data on the microbial ecology of permafrost and provides a platform for understanding microbial life strategies in frozen soil as well as the impact of climate change on permafrost microorganisms and their functional roles....

  13. The long-term fate of permafrost peatlands under rapid climate warming

    DEFF Research Database (Denmark)

    Swindles, Graeme T.; Morris, Paul J.; Mullan, Donal

    2015-01-01

    Permafrost peatlands contain globally important amounts of soil organic carbon, owing to cold conditions which suppress anaerobic decomposition. However, climate warming and permafrost thaw threaten the stability of this carbon store. The ultimate fate of permafrost peatlands and their carbon...... stores is unclear because of complex feedbacks between peat accumulation, hydrology and vegetation. Field monitoring campaigns only span the last few decades and therefore provide an incomplete picture of permafrost peatland response to recent rapid warming. Here we use a high-resolution palaeoecological...... approach to understand the longer-term response of peatlands in contrasting states of permafrost degradation to recent rapid warming. At all sites we identify a drying trend until the late-twentieth century; however, two sites subsequently experienced a rapid shift to wetter conditions as permafrost thawed...

  14. Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi 2 Se 3

    KAUST Repository

    Kong, Desheng

    2011-06-28

    Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi2Se3 gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi2Se3 nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi2Se3 under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi2Se3 by transport measurements. © 2011 American Chemical Society.

  15. Evaluating Ecotypes as a means of Scaling-up Permafrost Thermal Measurements in Western Alaska.

    Science.gov (United States)

    Cable, William; Romanovsky, Vladimir

    2015-04-01

    In many regions, permafrost temperatures are increasing due to climate change and in some cases permafrost is thawing and degrading. In areas where degradation has already occurred the effects can be dramatic, resulting in changing ecosystems, carbon release, and damage to infrastructure. Yet in many areas we lack baseline data, such as subsurface temperatures, needed to assess future changes and potential risk areas. Besides climate, the physical properties of the vegetation cover and subsurface material have a major influence on the thermal state of permafrost. These properties are often directly related to the type of ecosystem overlaying permafrost. Thus, classifying the landscape into general ecotypes might be an effective way to scale up permafrost thermal data. To evaluate using ecotypes as a way of scaling-up permafrost thermal data within a region we selected an area in Western Alaska, the Selawik National Wildlife Refuge, which is on the boundary between continuous and discontinuous permafrost. This region was selected because previously an ecological land classification had been conducted and a very high-resolution ecotype map was generated. Using this information we selected 18 spatially distributed sites covering the most abundant ecotypes, where we are collecting low vertical resolution soil temperature data to a depth of 1.5 meters at most sites. At three additional core sites, we are collecting air temperature, snow depth, and high vertical resolution soil temperature to a depth of 3 meters. The sites were installed in the summers of 2011 and 2012; consequently, we have at least two years of data from all sites. Mean monthly and mean annual air temperature and snow depth for all three core sites are similar within the 2012-2014 period. Additionally, the average air temperature and snow depth from our three cores sites compares well with that of a nearby meteorological station for which long-term data is available. During the study period snow depth

  16. Change in Spatial Distribution of Permafrost in the Source Area of the Yellow River: A Numerical Prediction

    Science.gov (United States)

    Ma, S.; Sheng, Y.; Wu, J.; Hu, X.; Li, J.

    2017-12-01

    Permafrost plays an important role in the climate system through its influence on energy exchanges, hydrological processes, natural hazards and carbon budgets. As a response to the global warming, permafrost is degrading with various manifestations, such as increase in permafrost temperature, thickening of active layer, permafrost disappearance. The Source Area of the Yellow River is located in the mosaic transition zones of seasonally frozen ground, and discontinuous and continuous permafrost on the northeastern Qinghai-Tibet Plateau. Based on the prediction results of the climate model in the IPCC Fifth Assessment Report, this article attempts to forecast the change of the typical permafrost types in the SAYR by using the numerical simulation method. And we calculate the spatial distribution of permafrost in the past and predict the change trend of permafrost in the future. The results show that only a small part of the permafrost in this region has degraded in1972 2012 and the degraded area is about 279 km2. The seasonal frozen soil is mainly distributed in the valley of Re Qu, Xiaoyemaling and Tangchama in the south of the two lake basins. There is little area difference on the permafrost degrading into the seasonal frozen soil under the scenarios of RCP2.6, RCP6.0, RCP8.5 in 2050. The degrading area of permafrost is 2224 km2, 2347 km2, 2559 km2. They account for 7.5%, 7.9%, 8.6% of the Source Area, respectively. And the seasonal frozen soil is sporadically distributed in Lena Qu, Duo Qu, Baima Qu. They widely spread on Yeniugou, Yeniutan and four Madio lakes being located in the Yellow River valley of the eastern part of Ngoring Lake. In 2100, the area of permafrost degradation is 5636 km2, 9769 km2, 15548 km2. They accounts for 19%, 32.9% and 52.3% of the source area, respectively. The permafrost mainly degenerate in the area of Xingsuhai, Gamaletan, Duogerong. Permafrost influences hydrology by providing an impermeable barrier to the movement of liquid water

  17. Characterization of atrial natriuretic peptide degradation by cell-surface peptidase activity on endothelial cells

    Science.gov (United States)

    Frost, S. J.; Whitson, P. A.

    1993-01-01

    Atrial natriuretic peptide (ANP) is a fluid-regulating peptide hormone that promotes vasorelaxation, natriuresis, and diuresis. The mechanisms for the release of ANP and for its clearance from the circulation play important roles in modulating its biological effects. Recently, we have reported that the cell surface of an endothelial cell line, CPA47, could degrade 125I-ANP in the presence of EDTA. In this study, we have characterized this degradation of 125I-ANP. The kinetics of ANP degradation by the surface of CPA47 cells were first order, with a Km of 320 +/- 60 nM and Vmax of 35 +/- 14 pmol of ANP degraded/10 min/10(5) cells at pH 7.4. ANP is degraded by the surface of CPA47 cells over a broad pH range from 7.0-8.5. Potato carboxypeptidase inhibitor and bestatin inhibited 125I-ANP degradation, suggesting that this degradative activity on the surface of CPA47 cells has exopeptidase characteristics. The selectivity of CPA47 cell-surface degradation of ANP was demonstrated when 125I-ANP degradation was inhibited in the presence of neuropeptide Y and angiotensin I and II but not bradykinin, bombesin, endothelin-1, or substance P. The C-terminal amino acids phe26 and tyr28 were deduced to be important for ANP interaction with the cell-surface peptidase(s) based on comparison of the IC50 of various ANP analogues and other natriuretic peptides for the inhibition of ANP degradation. These data suggest that a newly characterized divalent cation-independent exopeptidase(s) that selectively recognizes ANP and some other vasoactive peptides exists on the surface of endothelial cells.

  18. Study of the Qinghai-Tibetan Plateau Permafrost Active Layer Thickening Rate Using ALOS-1/-2 Interferometric SAR Data

    Science.gov (United States)

    Jia, Y.; Shum, C. K.; Kim, J.; Lu, Z.; Kuo, C. Y.; Zhang, L.; Ding, X.

    2016-12-01

    The Qinghai-Tibetan Plateau(QTP) 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. The QTP is covered by a large (1.3 to 1.6 million km2) layer of discontinuous and sporadic alpine permafrost, and is the origin of the largest rivers across Asia, feeding water to billions of people downstream. One such origin is the Three-River Headwater System, comprising of the mighty Yangtze, Yellow, and Lancang/Mekong Rivers, a subject of this study. The thawing over QTP permafrost regions is thought to be more severe compared with other high latitude permafrost regions by the fact that most of the permafrost is warm. During the past few decades, 10% permafrost has degraded. The overall mean active layer (AL) thickening rates over the QTP from model studies were 1.4 cm yr-1 during 1980-2001 and approximately 6.3 cm yr-1 during 2006-2010, based on soil temperature profiles for 27 monitoring sites along Qinghai-Tibetan railway (QTR). Here we report on a study on quantifying AL thickening rate in the northern QTP along the QTR, using ALOS-1/-2 InSAR observed land subsidence and AL thickness modeling. We have characterized high spatial resolution (30 m) and spatially varying ALT thickening rates, 2007-2010, along the QTR's large permafrost areas (> 10,000 km2). InSAR measured subsidence rates over various thermokarst surfaces in the study region are then converted to AL thickening rates using models with estimates ranging from 2.0 cm yr-1 to 10.7 cm yr-1. Comparisons with five borehole in situ sites showed excellent agreements with r2 >0.9. Using the ALOS-1/-2 InSAR data, we have further studied the plausible contribution of permafrost in NE QTP to the Yangtze headwater runoff near the Tuotuo river.

  19. Electron acceptor-based regulation of microbial greenhouse gas production from thawing permafrost

    DEFF Research Database (Denmark)

    Bak, Ebbe Norskov; Jones, Eleanor; Yde, Jacob Clement

    Permafrost contains about 35% of the global soil organic carbon (0-3 m depth). As a consequence of global warming, the active layer thickness is steadily increasing and its organic carbon is becoming available for degradation, causing a concomitant release of CO2 and CH4. The climate forcing...... of sulfate and iron and the microbial community structure regulate the production of CO2 and CH4 in thawing permafrost, and to elucidate how the rate of the organic carbon degradation changes with depth in permafrost-affected soils. This study improves our understanding of climate feedback mechanisms...

  20. Surface degradation and aging in YBa2Cu3O7-x ceramics

    International Nuclear Information System (INIS)

    Larkins, G.L. Jr.; Jones, W.K.; Kennedy, R.J.

    1991-01-01

    One of the major problems with the YBa 2 Cu 3 O 7 (123) superconductor is surface degradation and instability in a variety of environments, particularly those which include water. In the present work, we report on a novel method of determining the rate of formation and impedance of the degraded surface using an in-situ and real-time surface impedance measurement technique. The surface was found to degrade even in inert environments and a significant difference in the change of the surface impedance with the presence of water vapor in the test environment was also noted. The results and applications of this technique are confirmed by classical surface analysis techniques. (orig./BHO)

  1. Influence of permafrost distribution on groundwater flow in the context of climate-driven permafrost thaw: example from Yukon Flats Basin, Alaska, United States

    Science.gov (United States)

    Walvoord, Michelle Ann; Voss, Clifford I.; Wellman, Tristan P.

    2012-01-01

    Understanding the role of permafrost in controlling groundwater flow paths and fluxes is central in studies aimed at assessing potential climate change impacts on vegetation, species habitat, biogeochemical cycling, and biodiversity. Recent field studies in interior Alaska show evidence of hydrologic changes hypothesized to result from permafrost degradation. This study assesses the hydrologic control exerted by permafrost, elucidates modes of regional groundwater flow for various spatial permafrost patterns, and evaluates potential hydrologic consequences of permafrost degradation. The Yukon Flats Basin (YFB), a large (118,340 km2) subbasin within the Yukon River Basin, provides the basis for this investigation. Model simulations that represent an assumed permafrost thaw sequence reveal the following trends with decreasing permafrost coverage: (1) increased groundwater discharge to rivers, consistent with historical trends in base flow observations in the Yukon River Basin, (2) potential for increased overall groundwater flux, (3) increased spatial extent of groundwater discharge in lowlands, and (4) decreased proportion of suprapermafrost (shallow) groundwater contribution to total base flow. These trends directly affect the chemical composition and residence time of riverine exports, the state of groundwater-influenced lakes and wetlands, seasonal river-ice thickness, and stream temperatures. Presently, the YFB is coarsely mapped as spanning the continuous-discontinuous permafrost transition that model analysis shows to be a critical threshold; thus, the YFB may be on the verge of major hydrologic change should the current permafrost extent decrease. This possibility underscores the need for improved characterization of permafrost and other hydrogeologic information in the region via geophysical techniques, remote sensing, and ground-based observations.

  2. DOE Final Report on Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States); Schlosser, C. Adam [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Melillo, Jerry M. [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Anthony, Katey Walter [Univ. of Alaska, Fairbanks, AK (United States); Kicklighter, David [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Gao, Xiang [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-11-03

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  3. The Impacts of Thawing Permafrost and Climate Change on USAF Infrastructure Within Northern Tier Bases

    Science.gov (United States)

    Graboski, A. J.

    2016-12-01

    The Department of Defense (DoD) is planning over $600M in military construction on Eielson Air Force Base (AFB) within the next three fiscal years. Although many studies have been conducted on permafrost and climate change, the future of our climate as well as any impacts on arctic infrastructure, remains unclear. This research focused on future climate predictions to determine likely scenarios for the United States Air Force's Strategic Planners to consider. This research also looked at various construction methods being used by industry to glean best practices to incorporate into future construction in order to determine cost factors to consider when permafrost soils may be encountered. The most recent 2013 International Panel on Climate Change (IPCC) report predicts a 2.2ºC to 7.8ºC temperature rise in Arctic regions by the end of the 21st Century in the Representative Concentration Pathways, (RCP4.5) emissions scenario. A regression model was created using archived surface observations from 1944 to 2016. Initial analysis using regression/forecast techniques show a 1.17ºC temperature increase in the Arctic by the end of the 21st Century. Historical DoD construction data was then used to determine an appropriate cost factor. Applying statistical tests to the adjusted climate predictions supports continued usage of current DoD cost factors of 2.13 at Eielson and 2.97 at Thule AFBs as they should be sufficient when planning future construction projects in permafrost rich areas. These cost factors should allow planners the necessary funds to plan foundation mitigation techniques and prevent further degradation of permafrost soils around airbase infrastructure. This current research focused on Central Alaska while further research is recommended on the Alaskan North Slope and Greenland to determine climate change impacts on critical DoD infrastructure.

  4. Permafrost collapse alters soil carbon stocks, respiration, CH4 , and N2O in upland tundra.

    Science.gov (United States)

    Abbott, Benjamin W; Jones, Jeremy B

    2015-12-01

    Release of greenhouse gases from thawing permafrost is potentially the largest terrestrial feedback to climate change and one of the most likely to occur; however, estimates of its strength vary by a factor of thirty. Some of this uncertainty stems from abrupt thaw processes known as thermokarst (permafrost collapse due to ground ice melt), which alter controls on carbon and nitrogen cycling and expose organic matter from meters below the surface. Thermokarst may affect 20-50% of tundra uplands by the end of the century; however, little is known about the effect of different thermokarst morphologies on carbon and nitrogen release. We measured soil organic matter displacement, ecosystem respiration, and soil gas concentrations at 26 upland thermokarst features on the North Slope of Alaska. Features included the three most common upland thermokarst morphologies: active-layer detachment slides, thermo-erosion gullies, and retrogressive thaw slumps. We found that thermokarst morphology interacted with landscape parameters to determine both the initial displacement of organic matter and subsequent carbon and nitrogen cycling. The large proportion of ecosystem carbon exported off-site by slumps and slides resulted in decreased ecosystem respiration postfailure, while gullies removed a smaller portion of ecosystem carbon but strongly increased respiration and N2 O concentration. Elevated N2 O in gully soils persisted through most of the growing season, indicating sustained nitrification and denitrification in disturbed soils, representing a potential noncarbon permafrost climate feedback. While upland thermokarst formation did not substantially alter redox conditions within features, it redistributed organic matter into both oxic and anoxic environments. Across morphologies, residual organic matter cover, and predisturbance respiration explained 83% of the variation in respiration response. Consistent differences between upland thermokarst types may contribute to the

  5. An observation-based constraint on permafrost loss as a function of global warming

    Science.gov (United States)

    Chadburn, S. E.; Burke, E. J.; Cox, P. M.; Friedlingstein, P.; Hugelius, G.; Westermann, S.

    2017-04-01

    Permafrost, which covers 15 million km2 of the land surface, is one of the components of the Earth system that is most sensitive to warming. Loss of permafrost would radically change high-latitude hydrology and biogeochemical cycling, and could therefore provide very significant feedbacks on climate change. The latest climate models all predict warming of high-latitude soils and thus thawing of permafrost under future climate change, but with widely varying magnitudes of permafrost thaw. Here we show that in each of the models, their present-day spatial distribution of permafrost and air temperature can be used to infer the sensitivity of permafrost to future global warming. Using the same approach for the observed permafrost distribution and air temperature, we estimate a sensitivity of permafrost area loss to global mean warming at stabilization of million km2 °C-1 (1σ confidence), which is around 20% higher than previous studies. Our method facilitates an assessment for COP21 climate change targets: if the climate is stabilized at 2 °C above pre-industrial levels, we estimate that the permafrost area would eventually be reduced by over 40%. Stabilizing at 1.5 °C rather than 2 °C would save approximately 2 million km2 of permafrost.

  6. Quantifying uncertainties of permafrost carbon-climate feedbacks

    Science.gov (United States)

    Burke, Eleanor J.; Ekici, Altug; Huang, Ye; Chadburn, Sarah E.; Huntingford, Chris; Ciais, Philippe; Friedlingstein, Pierre; Peng, Shushi; Krinner, Gerhard

    2017-06-01

    The land surface models JULES (Joint UK Land Environment Simulator, two versions) and ORCHIDEE-MICT (Organizing Carbon and Hydrology in Dynamic Ecosystems), each with a revised representation of permafrost carbon, were coupled to the Integrated Model Of Global Effects of climatic aNomalies (IMOGEN) intermediate-complexity climate and ocean carbon uptake model. IMOGEN calculates atmospheric carbon dioxide (CO2) and local monthly surface climate for a given emission scenario with the land-atmosphere CO2 flux exchange from either JULES or ORCHIDEE-MICT. These simulations include feedbacks associated with permafrost carbon changes in a warming world. Both IMOGEN-JULES and IMOGEN-ORCHIDEE-MICT were forced by historical and three alternative future-CO2-emission scenarios. Those simulations were performed for different climate sensitivities and regional climate change patterns based on 22 different Earth system models (ESMs) used for CMIP3 (phase 3 of the Coupled Model Intercomparison Project), allowing us to explore climate uncertainties in the context of permafrost carbon-climate feedbacks. Three future emission scenarios consistent with three representative concentration pathways were used: RCP2.6, RCP4.5 and RCP8.5. Paired simulations with and without frozen carbon processes were required to quantify the impact of the permafrost carbon feedback on climate change. The additional warming from the permafrost carbon feedback is between 0.2 and 12 % of the change in the global mean temperature (ΔT) by the year 2100 and 0.5 and 17 % of ΔT by 2300, with these ranges reflecting differences in land surface models, climate models and emissions pathway. As a percentage of ΔT, the permafrost carbon feedback has a greater impact on the low-emissions scenario (RCP2.6) than on the higher-emissions scenarios, suggesting that permafrost carbon should be taken into account when evaluating scenarios of heavy mitigation and stabilization. Structural differences between the land

  7. Quantifying uncertainties of permafrost carbon–climate feedbacks

    Directory of Open Access Journals (Sweden)

    E. J. Burke

    2017-06-01

    Full Text Available The land surface models JULES (Joint UK Land Environment Simulator, two versions and ORCHIDEE-MICT (Organizing Carbon and Hydrology in Dynamic Ecosystems, each with a revised representation of permafrost carbon, were coupled to the Integrated Model Of Global Effects of climatic aNomalies (IMOGEN intermediate-complexity climate and ocean carbon uptake model. IMOGEN calculates atmospheric carbon dioxide (CO2 and local monthly surface climate for a given emission scenario with the land–atmosphere CO2 flux exchange from either JULES or ORCHIDEE-MICT. These simulations include feedbacks associated with permafrost carbon changes in a warming world. Both IMOGEN–JULES and IMOGEN–ORCHIDEE-MICT were forced by historical and three alternative future-CO2-emission scenarios. Those simulations were performed for different climate sensitivities and regional climate change patterns based on 22 different Earth system models (ESMs used for CMIP3 (phase 3 of the Coupled Model Intercomparison Project, allowing us to explore climate uncertainties in the context of permafrost carbon–climate feedbacks. Three future emission scenarios consistent with three representative concentration pathways were used: RCP2.6, RCP4.5 and RCP8.5. Paired simulations with and without frozen carbon processes were required to quantify the impact of the permafrost carbon feedback on climate change. The additional warming from the permafrost carbon feedback is between 0.2 and 12 % of the change in the global mean temperature (ΔT by the year 2100 and 0.5 and 17 % of ΔT by 2300, with these ranges reflecting differences in land surface models, climate models and emissions pathway. As a percentage of ΔT, the permafrost carbon feedback has a greater impact on the low-emissions scenario (RCP2.6 than on the higher-emissions scenarios, suggesting that permafrost carbon should be taken into account when evaluating scenarios of heavy mitigation and stabilization

  8. Relationship between Mineral Soil Surface Area and the Biological Degradation of Biosolids Added to Soil

    Directory of Open Access Journals (Sweden)

    Dongqi Wen

    2015-12-01

    Full Text Available Geochemical and biological processes that operate in the soil matrix and on the soil surface are important to the degradation of biosolids in soil. Due to the large surface area of soils it is assumed that the microbial ecology is associated with mineral soil surface area. The total mineral surface areas were determined for soils from eight different fields selected from a long term study (1972–2006 of annual biosolids application to 41 fields in central Illinois varying in size from 3.6 to 66 ha. The surface areas for the soils varied from 1 to 9 m2/g of soil. The biological degradation rates for the eight soils were determined using a biological degradation rate model (DRM and varied from 0.02 to 0.20/year−1. Regression analysis revealed that the degradation rate was positively associated with mineral soil surface area (1 m2/g produces 0.018 year−1 increase in the degradation rate. The annual soil sequestration rate was calculated to increase from 1% to 6% when the soil total surface area increased from 1 to 9 m2/g of soil. Therefore, land application of biosolids is an effective way to enhance carbon sequestration in soils and reduce greenhouse gas emissions.

  9. What's down below? Current and potential future applications of geophysical techniques to identify subsurface permafrost conditions (Invited)

    Science.gov (United States)

    Douglas, T. A.; Bjella, K.; Campbell, S. W.

    2013-12-01

    For infrastructure design, operations, and maintenance requirements in the North the ability to accurately and efficiently detect the presence (or absence) of ground ice in permafrost terrains is a serious challenge. Ground ice features including ice wedges, thermokarst cave-ice, and segregation ice are present in a variety of spatial scales and patterns. Currently, most engineering applications use borehole logging and sampling to extrapolate conditions at the point scale. However, there is high risk of over or under estimating the presence of frozen or unfrozen features when relying on borehole information alone. In addition, boreholes are costly, especially for planning linear structures like roads or runways. Predicted climate warming will provide further challenges for infrastructure development and transportation operations where permafrost degradation occurs. Accurately identifying the subsurface character in permafrost terrains will allow engineers and planners to cost effectively create novel infrastructure designs to withstand the changing environment. There is thus a great need for a low cost rapidly deployable, spatially extensive means of 'measuring' subsurface conditions. Geophysical measurements, both terrestrial and airborne, have strong potential to revolutionize our way of mapping subsurface conditions. Many studies in continuous and discontinuous permafrost have used geophysical measurements to identify discrete features and repeatable patterns in the subsurface. The most common measurements include galvanic and capacitive coupled resistivity, ground penetrating radar, and multi frequency electromagnetic induction techniques. Each of these measurements has strengths, weaknesses, and limitations. By combining horizontal geophysical measurements, downhole geophysics, multispectral remote sensing images, LiDAR measurements, and soil and vegetation mapping we can start to assemble a holistic view of how surface conditions and standoff measurements

  10. High risk of permafrost thaw

    Science.gov (United States)

    E.A.G. Schuur; B.W. Abbott; W.B. Bowden; V. Brovkin; P. Camill; J.P. Canadell; F.S. Chapin; T.R. Christensen; J.P. Chanton; P. Ciais; P.M. Crill; B.T. Crosby; C.I. Czimczik; G. Grosse; D.J. Hayes; G. Hugelius; J.D. Jastrow; T. Kleinen; C.D. Koven; G. Krinner; P. Kuhry; D.M. Lawrence; S.M. Natali; C.L. Ping; A. Rinke; W.J. Riley; V.E. Romanovsky; A.B.K. Sannel; C. Schadel; K. Schaefer; Z.M. Subin; C. Tarnocai; M. Turetsky; K. M. Walter-Anthony; C.J. Wilson; S.A. Zimov

    2011-01-01

    Arctic temperatures are rising fast, and permafrost is thawing. Carbon released into the atmosphere from permafrost soils will accelerate climate change, but the magnitude of this effect remains highly uncertain. Our collective estimate is that carbon will be released more quickly than models suggest, and at levels that are cause for serious concern. We calculate that...

  11. In situ nuclear magnetic response of permafrost and active layer soil in boreal and tundra ecosystems

    DEFF Research Database (Denmark)

    Kass, Mason Andrew; Irons, Trevor; Minsley, Burke J.

    2017-01-01

    of the nuclear magnetic resonance (NMR) response of the active layer and permafrost in a variety of soil conditions, types, and saturations. In this paper, we summarize the NMR data and present quantitative relationships between active layer and permafrost liquid water content and pore sizes and show......Characterization of permafrost, particularly warm and near-surface permafrost which can contain significant liquid water, is critical to understanding complex interrelationships with climate change, ecosystems, and disturbances such as wildfires. Understanding the vulnerability and resilience...

  12. Examining Environmental Gradients with Remotely Sensed Data - the ESA GlobPermafrost project

    Science.gov (United States)

    Bartsch, Annett; Grosse, Guido; Kääb, Andreas; Westermann, Sebastian; Strozzi, Tazio; Wiesmann, Andreas; Duguay, Claude; Seifert, Frank Martin; Obu, Jaroslav; Nitze, Ingmar; Heim, Birgit; Haas, Antoni; Widhalm, Barbara

    2017-04-01

    Permafrost cannot be directly detected from space, but many surface features of permafrost terrains and typical periglacial landforms are observable with a variety of EO sensors ranging from very high to medium resolution at various wavelengths. In addition, landscape dynamics associated with permafrost changes and geophysical variables relevant for characterizing the state of permafrost, such as land surface temperature or freeze-thaw state can be observed with space-based Earth Observation. Suitable regions to examine environmental gradients across the Arctic have been defined in a community white paper (Bartsch et al. 2014). These transects have been updated within the ESA DUE GlobPermafrost project. The ESA DUE GlobPermafrost project develops, validates and implements Earth Observation (EO) products to support research communities and international organisations in their work on better understanding permafrost characteristics and dynamics. Prototype product cases will cover different aspects of permafrost by integrating in situ measurements of subsurface properties and surface properties, Earth Observation, and modelling to provide a better understanding of permafrost today. The project will extend local process and permafrost monitoring to broader spatial domains, support permafrost distribution modelling, and help to implement permafrost landscape and feature mapping in a GIS framework. It will also complement active layer and thermal observing networks. Both lowland (latitudinal) and mountain (altitudinal) permafrost issues are addressed. The selected transects and first results will be presented. This includes identified needs from the user requirements survey, a review of existing land surface products available for the Arctic as well as prototypes of GlobPermafrost datasets, and the permafrost information system through which they can be accessed. Bartsch, Annett; Allard, Michel; Biskaborn, Boris Kolumban; Burba, George; Christiansen, Hanne H; Duguay

  13. Characteristics of ground motion at permafrost sites along the Qinghai-Tibet railway

    Science.gov (United States)

    Wang, L.; Wu, Z.; Sun, Jielun; Liu, Xiuying; Wang, Z.

    2009-01-01

    Based on 14 typical drilling holes distributed in the permafrost areas along the Qinghai-Tibet railway, the distribution of wave velocities of soils in the permafrost regions were determined. Using results of dynamic triaxial tests, the results of dynamic triaxiality test and time histories of ground motion acceleration in this area, characteristics of ground motion response were analyzed for these permafrost sites for time histories of ground accelerations with three exceedance probabilities (63%, 10% and 2%). The influence of ground temperature on the seismic displacement, velocity, acceleration and response spectrum on the surface of permafrost were also studied. ?? 2008 Elsevier Ltd. All rights reserved.

  14. Distinguishing between old and modern permafrost sources in the northeast Siberian land-shelf system with compound-specific δ2H analysis

    Science.gov (United States)

    Vonk, Jorien E.; Tesi, Tommaso; Bröder, Lisa; Holmstrand, Henry; Hugelius, Gustaf; Andersson, August; Dudarev, Oleg; Semiletov, Igor; Gustafsson, Örjan

    2017-08-01

    Pleistocene ice complex permafrost deposits contain roughly a quarter of the organic carbon (OC) stored in permafrost (PF) terrain. When permafrost thaws, its OC is remobilized into the (aquatic) environment where it is available for degradation, transport or burial. Aquatic or coastal environments contain sedimentary reservoirs that can serve as archives of past climatic change. As permafrost thaw is increasing throughout the Arctic, these reservoirs are important locations to assess the fate of remobilized permafrost OC.We here present compound-specific deuterium (δ2H) analysis on leaf waxes as a tool to distinguish between OC released from thawing Pleistocene permafrost (ice complex deposits; ICD) and from thawing Holocene permafrost (from near-surface soils). Bulk geochemistry (%OC; δ13C; %total nitrogen, TN) was analyzed as well as the concentrations and δ2H signatures of long-chain n-alkanes (C21 to C33) and mid- to long-chain n-alkanoic acids (C16 to C30) extracted from both ICD-PF samples (n = 9) and modern vegetation and O-horizon (topsoil-PF) samples (n = 9) from across the northeast Siberian Arctic. Results show that these topsoil-PF samples have higher %OC, higher OC / TN values and more depleted δ13C-OC values than ICD-PF samples, suggesting that these former samples trace a fresher soil and/or vegetation source. Whereas the two investigated sources differ on the bulk geochemical level, they are, however, virtually indistinguishable when using leaf wax concentrations and ratios. However, on the molecular isotope level, leaf wax biomarker δ2H values are statistically different between topsoil PF and ICD PF. For example, the mean δ2H value of C29 n-alkane was -246 ± 13 ‰ (mean ± SD) for topsoil PF and -280 ± 12 ‰ for ICD PF. With a dynamic isotopic range (difference between two sources) of 34 to 50 ‰; the isotopic fingerprints of individual, abundant, biomarker molecules from leaf waxes can thus serve as endmembers to distinguish between

  15. Detecting the permafrost carbon feedback: talik formation and increased cold-season respiration as precursors to sink-to-source transitions

    Directory of Open Access Journals (Sweden)

    N. C. Parazoo

    2018-01-01

    Full Text Available Thaw and release of permafrost carbon (C due to climate change is likely to offset increased vegetation C uptake in northern high-latitude (NHL terrestrial ecosystems. Models project that this permafrost C feedback may act as a slow leak, in which case detection and attribution of the feedback may be difficult. The formation of talik, a subsurface layer of perennially thawed soil, can accelerate permafrost degradation and soil respiration, ultimately shifting the C balance of permafrost-affected ecosystems from long-term C sinks to long-term C sources. It is imperative to understand and characterize mechanistic links between talik, permafrost thaw, and respiration of deep soil C to detect and quantify the permafrost C feedback. Here, we use the Community Land Model (CLM version 4.5, a permafrost and biogeochemistry model, in comparison to long-term deep borehole data along North American and Siberian transects, to investigate thaw-driven C sources in NHL ( >  55° N from 2000 to 2300. Widespread talik at depth is projected across most of the NHL permafrost region (14 million km2 by 2300, 6.2 million km2 of which is projected to become a long-term C source, emitting 10 Pg C by 2100, 50 Pg C by 2200, and 120 Pg C by 2300, with few signs of slowing. Roughly half of the projected C source region is in predominantly warm sub-Arctic permafrost following talik onset. This region emits only 20 Pg C by 2300, but the CLM4.5 estimate may be biased low by not accounting for deep C in yedoma. Accelerated decomposition of deep soil C following talik onset shifts the ecosystem C balance away from surface dominant processes (photosynthesis and litter respiration, but sink-to-source transition dates are delayed by 20–200 years by high ecosystem productivity, such that talik peaks early ( ∼  2050s, although borehole data suggest sooner and C source transition peaks late ( ∼  2150–2200. The

  16. A preformulation evaluation of a photosensitive surface active compound, explaining concentration dependent degradation.

    Science.gov (United States)

    Sigfridsson, Kalle; Carlsson, Karin E

    2017-11-15

    A candidate drug within the cardiovascular area was identified during early research and evaluated for further development. The aim was to understand and explain the degradation mechanisms for the present compound. The stability of the active pharmaceutical ingredient (API) in solution and solid state was studied during different conditions. The bulk compound was exposed to elevated temperatures, increased relative humidity and stressed light conditions. Degradation of the drug in solutions was followed in the presence versus absence of ethylenediaminetetraacetic acid (EDTA), during aerobic versus anaerobic conditions, stored protected from light versus exposed to light and as a function of pH and concentration. It was possible to improve the stability by adding EDTA and completely abolish degradation by storing dissolved compound at anaerobic conditions. Solutions of API were stable between pH3 and 7, with some degradation at pH1, when stored protected from light and at 22°C, but degrade rapidly when exposed to ambient light conditions. The degradation products were identified by mass spectroscopy. Degradation schemes were drawn. There was concentration dependence in the degradation of dissolved drug when exposed to light, showing a titration behavior that concurred with the measured critical micelle/aggregation concentration (CMC/CAC) of the compound. The compound was stable in solution during the investigated time period, at concentrations above CMC/CAC, where the molecule was protected from photodegradation when the compound aggregated. Below CMC/CAC, a significant degradation of the API occurred. This may be a potential explanation why other surface active compounds show concentration dependent degradation. The photosensitivity was also observed for the neutral compound in crystalline and amorphous form, as well as for the crystalline chloride salt of the drug. However, the degradation of amorphous form was faster compared to crystalline material. No

  17. NORPERM, the Norwegian Permafrost Database - a TSP NORWAY IPY legacy

    Science.gov (United States)

    Juliussen, H.; Christiansen, H. H.; Strand, G. S.; Iversen, S.; Midttømme, K.; Rønning, J. S.

    2010-10-01

    NORPERM, the Norwegian Permafrost Database, was developed at the Geological Survey of Norway during the International Polar Year (IPY) 2007-2009 as the main data legacy of the IPY research project Permafrost Observatory Project: A Contribution to the Thermal State of Permafrost in Norway and Svalbard (TSP NORWAY). Its structural and technical design is described in this paper along with the ground temperature data infrastructure in Norway and Svalbard, focussing on the TSP NORWAY permafrost observatory installations in the North Scandinavian Permafrost Observatory and Nordenskiöld Land Permafrost Observatory, being the primary data providers of NORPERM. Further developments of the database, possibly towards a regional database for the Nordic area, are also discussed. The purpose of NORPERM is to store ground temperature data safely and in a standard format for use in future research. The IPY data policy of open, free, full and timely release of IPY data is followed, and the borehole metadata description follows the Global Terrestrial Network for Permafrost (GTN-P) standard. NORPERM is purely a temperature database, and the data is stored in a relation database management system and made publically available online through a map-based graphical user interface. The datasets include temperature time series from various depths in boreholes and from the air, snow cover, ground-surface or upper ground layer recorded by miniature temperature data-loggers, and temperature profiles with depth in boreholes obtained by occasional manual logging. All the temperature data from the TSP NORWAY research project is included in the database, totalling 32 temperature time series from boreholes, 98 time series of micrometeorological temperature conditions, and 6 temperature depth profiles obtained by manual logging in boreholes. The database content will gradually increase as data from previous and future projects are added. Links to near real-time permafrost temperatures, obtained

  18. Optical monitoring of surface processes relevant to thin film growth by chemical vapour deposition Oxidation; Surface degradation

    CERN Document Server

    Simcock, M N

    2002-01-01

    This thesis reports on the investigation of the use of reflectance anisotropy spectroscopy (RAS) as an in-situ monitor for the preparation and oxidation of GaAs(100) c(4x4) surfaces using a CVD 2000 MOCVD reactor. These surfaces were oxidised using air. It was found that it was possible to follow surface degradation using RA transients at 2.6eV and 4eV. From this data it was possible to speculate on the nature of the surface oxidation process. A study was performed into the rate of surface degradation under different concentrations of air, it was found that the relation between the air concentration and the surface degradation was complicated but that the behaviour of the first third of the degradation approximated a first order behaviour. An estimation of the activation energy of the process was then made, and an assessment of the potential use of the glove-box for STM studies which is an integral part of the MOCVD equipment was also made. Following this, a description is given of the construction of an inte...

  19. The Aiguille du Midi (Mont Blanc massif, European Alps): a unique high-Alpine site to study bedrock permafrost

    Science.gov (United States)

    Deline, P.; Bölhert, R.; Coviello, V.; Cremonese, E.; Gruber, S.; Jaillet, S.; Krautblatter, M.; Morra di Cella, U.; Noetzli, J.; Pogliotti, P.; Ravanel, L.; Sadier, B.; Verleysdonk, S.

    2009-12-01

    Permafrost and its change in steep high-Alpine rock walls remain insufficiently understood because of the difficulties of in situ measurements. A large proportion of permafrost studies is mainly based on modelling, with a few existing instrumented sites and a resulting lack of process understanding. Yet, a number of rockfalls that occurred in the last decade in the Alps are likely related to climatically-driven permafrost degradation, as indicated by ice in starting zones, increased air temperature, and modelling studies. Starting off in the framework of the French-Italian PERMAdataROC project and presently under development within the EU co-funded project PermaNET (Permafrost long-term monitoring network: www.permanet-alpinespace.eu), our investigations at the Aiguille du Midi begin in 2005. The summit (3842 m a.s.l) is accessible from Chamonix by a cable car which was built at the end of the 1950s. Half a million tourists visit the site each year. Because of its elevation, geometry, and year-round accessibility to rock slopes of diverse aspects and to galleries, the site was chosen for: - Monitoring of the thermal regime in steep rock walls. Sensors with one or three thermistors were installed since 2005 at depths of 3, 10, 30 and 55 cm, and three 15-thermistor chains were set up in 10-m-deep boreholes this autumn, at all aspects and with slope angles in the range 60-90° (determining e.g. the presence and influence of snow). - Measurements of high altitude climatic data (air temperature and humidity, incoming and outgoing solar radiation, wind speed and direction) perpendicular to the rockwall surface, by movable automatic weather stations. Together with the rock temperature measurements, these data are used for physically-based model validation or statistical models construction of rock temperature distribution and variability in the rock walls. - Making an ‘in and out’ 3D-high-resolution DEM of the Aiguille by long-range (rock walls) and short

  20. Evaluating polymer degradation with complex mixtures using a simplified surface area method.

    Science.gov (United States)

    Steele, Kandace M; Pelham, Todd; Phalen, Robert N

    2017-09-01

    Chemical-resistant gloves, designed to protect workers from chemical hazards, are made from a variety of polymer materials such as plastic, rubber, and synthetic rubber. One material does not provide protection against all chemicals, thus proper polymer selection is critical. Standardized testing, such as chemical degradation tests, are used to aid in the selection process. The current methods of degradation ratings based on changes in weight or tensile properties can be expensive and data often do not exist for complex chemical mixtures. There are hundreds of thousands of chemical products on the market that do not have chemical resistance data for polymer selection. The method described in this study provides an inexpensive alternative to gravimetric analysis. This method uses surface area change to evaluate degradation of a polymer material. Degradation tests for 5 polymer types against 50 complex mixtures were conducted using both gravimetric and surface area methods. The percent change data were compared between the two methods. The resulting regression line was y = 0.48x + 0.019, in units of percent, and the Pearson correlation coefficient was r = 0.9537 (p ≤ 0.05), which indicated a strong correlation between percent weight change and percent surface area change. On average, the percent change for surface area was about half that of the weight change. Using this information, an equivalent rating system was developed for determining the chemical degradation of polymer gloves using surface area.

  1. Degradation of Reactive Yellow X-RG by O3/Fenton system: response surface approach, reaction mechanism, and degradation pathway.

    Science.gov (United States)

    Shen, Yongjun; Xu, Qihui; Liang, Jun; Xu, Wei

    2016-11-01

    O 3 /Fenton for the treatment of effluent containing Reactive Yellow X-RG is investigated. The response surface methodology is applied to study the main and interactive effects of the parameters. With the initial dye concentration being controlled at 300 mg L -1 , the optimized conditions for wastewater treatment are 3.68, 29.19 and 18.49 mg min -1 for initial pH, mole ratio of [H 2 O 2 ]/[Fe 2+ ] and ozone dosage, respectively. The regression quadratic model well describing the degradation efficiency of O 3 /Fenton process is developed and validated by the analysis of variances, respectively. In addition, a possible pathway for Reactive Yellow X-RG degradation is proposed by detecting the temporal evolution of intermediates in the solution, with the use of some techniques including ultraviolet spectrophotometric method (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC/MS). Meanwhile, every reaction step is given to explain the degradation mechanisms.

  2. In situ nuclear magnetic resonance response of permafrost and active layer soil in boreal and tundra ecosystems

    Science.gov (United States)

    Kass, M. Andy; Irons, Trevor P.; Minsley, Burke J.; Pastick, Neal J.; Brown, Dana R. N.; Wylie, Bruce K.

    2017-12-01

    Characterization of permafrost, particularly warm and near-surface permafrost which can contain significant liquid water, is critical to understanding complex interrelationships with climate change, ecosystems, and disturbances such as wildfires. Understanding the vulnerability and resilience of permafrost requires an interdisciplinary approach, relying on (for example) geophysical investigations, ecological characterization, direct observations, remote sensing, and more. As part of a multiyear investigation into the impacts of wildfires on permafrost, we have collected in situ measurements of the nuclear magnetic resonance (NMR) response of the active layer and permafrost in a variety of soil conditions, types, and saturations. In this paper, we summarize the NMR data and present quantitative relationships between active layer and permafrost liquid water content and pore sizes and show the efficacy of borehole NMR (bNMR) to permafrost studies. Through statistical analyses and synthetic freezing simulations, we also demonstrate that borehole NMR is sensitive to the nucleation of ice within soil pore spaces.

  3. In situ nuclear magnetic resonance response of permafrost and active layer soil in boreal and tundra ecosystems

    Directory of Open Access Journals (Sweden)

    M. A. Kass

    2017-12-01

    Full Text Available Characterization of permafrost, particularly warm and near-surface permafrost which can contain significant liquid water, is critical to understanding complex interrelationships with climate change, ecosystems, and disturbances such as wildfires. Understanding the vulnerability and resilience of permafrost requires an interdisciplinary approach, relying on (for example geophysical investigations, ecological characterization, direct observations, remote sensing, and more. As part of a multiyear investigation into the impacts of wildfires on permafrost, we have collected in situ measurements of the nuclear magnetic resonance (NMR response of the active layer and permafrost in a variety of soil conditions, types, and saturations. In this paper, we summarize the NMR data and present quantitative relationships between active layer and permafrost liquid water content and pore sizes and show the efficacy of borehole NMR (bNMR to permafrost studies. Through statistical analyses and synthetic freezing simulations, we also demonstrate that borehole NMR is sensitive to the nucleation of ice within soil pore spaces.

  4. CRYOLINK: Monitoring of permafrost and seasonal frost in southern Norway

    Science.gov (United States)

    Farbrot, Herman; Hipp, Tobias; Etzelmüller, Bernd; Humlum, Ole; Isaksen, Ketil; Strand Ødegârd, Rune

    2010-05-01

    The modern southern boundary for Scandinavian permafrost is located in the mountains of Southern Norway. Permafrost and seasonal frost are considered key components of the cryosphere, and the climate-permafrost relation has acquired added importance with the increasing awareness and concern of rising air temperatures. The three-year research project CRYOLINK ("Permafrost and seasonal frost in southern Norway") aims at improving knowledge on past and present ground temperatures, seasonal frost, and distribution of mountain permafrost in Southern Norway by addressing the fundamental problem of heat transfer between the atmosphere and the ground surface. Hence, several shallow boreholes have been drilled in August 2008 in three areas (Juvvass, Jetta and Tron) situated along a west-east transect. On most borehole sites air and ground temperatures are measured. Further, vertical arrays of Miniature Temperature Dataloggers (MTDs; Thermochron iBottons®) at fixed heights above the ground surface have been installed to roughly determine the snow depths at the sites, which is also indicated by digital cameras providing daily pictures of snow and weather conditions. In addition individual MTDs have been placed out to measure ground surface temperature at different aspects and snow settings. This presentation will focus on the field set up and give examples of data obtained from the sites.

  5. Subsea Permafrost Mapped Across the U.S. Beaufort Sea Using Multichannel Seismic Data

    Science.gov (United States)

    Brothers, L.; Hart, P. E.; Ruppel, C. D.

    2011-12-01

    Circum-Arctic continental shelves at water depths less than ~100 m were subaerial permafrost prior to the onset of sea-level rise starting in the late Pleistocene. Rapid transgression and the resulting temperature increase at the sediment surface have led to thawing of the inundated permafrost, landward retreat of the leading edge of the permafrost, and dissociation of permafrost-associated gas hydrates. Past numerical modeling has shown that gas hydrate dissociation is particularly pronounced at the permafrost-to-no permafrost transition offshore. On the U.S. Beaufort margin, subsea permafrost has never been systematically mapped, and the best insights about permafrost and associated gas hydrate have been based on a limited number of offshore boreholes and numerical studies, with sometimes contrasting predictions of the permafrost's seaward extent. We bring together 5370 km of multichannel seismic (MCS) data acquired during various proprietary exploration industry and public domain government surveys between 1977 and 1992 to map a velocity anomaly diagnostic of submerged permafrost along 500 km of the US Beaufort coastline. These high-velocity (>~2.8 km/s) refractions (HVR), which are evident in prestack MCS shot records, reveal laterally continuous layers of shallow, ice-bonded, coarse-grained sediments beneath the inner continental shelf. The HVR occur in less than 5% of the tracklines, and calculated HVR depths range from 60 to 350 m below seafloor. The velocity anomaly is not observed seaward of the 20 m isobath, and is only found within 30 km of the current shoreline. These results can be used to: 1) create a map of the minimum distribution of remaining US Beaufort shelf subsea permafrost; 2) reconcile discrepancies between model-predicted and borehole-verified offshore permafrost distribution; and 3) constrain where to expect hydrate dissociation.

  6. Collaborative Research: Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Melillo, Jerry [Marine Biological Lab., Woods Hole, MA (United States)

    2017-12-12

    Our overall goal in this research was to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal was motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we tested the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming. In collaboration with our Purdue and MIT colleagues, we have attempted to quantify global climate warming effects on land-atmosphere interactions, land-river network interactions, permafrost degradation, vegetation shifts, and land use influence water, carbon, and nitrogen fluxes to and from terrestrial ecosystems in the pan-arctic along with their

  7. 4-D permafrost thaw observations from ambient road traffic noise and a very dense distributed fiber optic sensing array

    Science.gov (United States)

    Lindsey, N.; Dou, S.; Martin, E. R.; Wagner, A. M.; Ajo Franklin, J. B.

    2017-12-01

    How does frozen soil thaw? The answer to this question affects hydrology, ecology, climate, and human infrastructure. We are using the local ambient noise field from a road recorded on a distributed fiber optic acoustic sensing (DAS) array to monitor the evolution in seismic parameters related to the top-down permafrost thaw process in the upper 10 m. Our field experiment demonstrates the advantages of "Large N" ambient noise studies using DAS, particularly to probe near surface critical zone dynamics. Over 60 days beginning in August 2016, we made continuous seismic recordings with a >4000 channel trenched fiber optic DAS dataset above a controlled permafrost warming demonstration experiment in Fairbanks, AK. The warming experiment accelerated the state of permafrost degradation by approximately two decades in a small 15 m x 20 m area, deepening the permafrost table from 4 m to 5.5 m. Continuous seismic DAS recording of high frequency surface waves (5-30 Hz) generated by vehicles traveling along a nearby road enables our investigation of hypothesized shear wave speed and attenuation changes, which lab measurements suggest may result from decreasing shear modulus and increasing saturation. We develop daily auto- and crosscorrelation function estimates using combinations of horizontal inline, collinear, and crossline DAS sensor orientations and vertical component geophone data, and then invert for maps of Love and Rayleigh wave speed that are sensitive to the upper 30 m. Many issues related to the accuracy, stability, and repeatability of the recovered empirical Green's tensor, as well as the sensitivity of the DAS sensor network will be considered.

  8. Permafrost at its limits: The most easterly evidence of existing permafrost in the European Alps as indicated by ground temperature and geoelectrical measurements

    Science.gov (United States)

    Kellerer-Pirklbauer, A.; Kühnast, B.

    2009-04-01

    Mountain permafrost is a widespread phenomenon in alpine regions in the European Alps. For instance, some 2000 km² or 4% of the Austrian Alps are underlain by permafrost. Up to recent times most research on permafrost issues in Austria focused on the central and highest section of the Austrian Alps. By contrast, knowledge concerning marginal permafrost zones is fairly limited. To increase knowledge about the easternmost limit of permafrost in the European Alps, a research project focusing on the Seckauer Tauern Mountains (14°30'E to 15°00'E) and particularly on the Hochreichart area was initiated in 2004 by the first author. Since then, different methods have been applied such as e.g. geomorphic mapping, numerical permafrost modelling, multi-annual BTS measurements (since 2004) or continuous ground surface and near ground surface temperature measurements by miniature temperature data loggers/MTDs (since 2004). In order to verify the temperature data and to extend the spatial knowledge about permafrost distribution beyond point information, a geoelectrical survey was carried out at the end of August 2008 by applying the electrical resistivity tomography (ERT) method along a 120 m long profile covering the upper part of the rooting zone of a (more-or-less) relict rock glacier and the talus slope above. For this survey the two-dimensional (2D) electrical surveys was performed using the Wenner-Alfa configuration with 2.5 m spacing and an LGM-Lippmann 4-Punkt light hp resistivity-meter. The ERT results indicate an active layer of 2 to 4 m underlain by a permafrost body along 3/4 of the entire profile with resistivity values between 50 to 100 kOhm.m and extending to a depth of 10 to 15 m. The permafrost body is substantially thicker at the lower part of the profile (rock glacier; first 50 m of profile) compared to most of the upper part (talus slope). Focusing on the talus slope, the permafrost body is thickest on the central section of the profile (~5-6 m thickness

  9. Isolation and characterization of diuron-degrading bacteria from lotic surface water.

    Science.gov (United States)

    Batisson, Isabelle; Pesce, Stéphane; Besse-Hoggan, Pascale; Sancelme, Martine; Bohatier, Jacques

    2007-11-01

    The bacterial community structure of a diuron-degrading enrichment culture from lotic surface water samples was analyzed and the diuron-degrading strains were selected using a series of techniques combining temporal temperature gradient gel electrophoresis (TTGE) of 16 S rDNA gene V1-V3 variable regions, isolation of strains on agar plates, colony hybridization methods, and biodegradation assays. The TTGE fingerprints revealed that diuron had a strong impact on bacterial community structure and highlighted both diuron-sensitive and diuron-adapted bacterial strains. Two bacterial strains, designated IB78 and IB93 and identified as belonging to Pseudomonas sp. and Stenotrophomonas sp., were isolated and shown to degrade diuron in pure resting cells in a first-order kinetic reaction during the first 24 h of incubation with no 3,4-DCA detected. The percentages of degradation varied from 25% to 60% for IB78 and 20% to 65% for IB93 and for a diuron concentration range from 20 mg/L to 2 mg/L, respectively. It is interesting to note that diuron was less degraded by single isolates than by mixed resting cells, thereby underlining a cumulative effect between these two strains. To the best of our knowledge, this is the first report of diuron-degrading strains isolated from lotic surface water.

  10. Degradation of the chemotherapy drug 5-fluorouracil on medical-grade silver surfaces

    Science.gov (United States)

    Risinggård, Helene Kjær; Cooil, Simon; Mazzola, Federico; Hu, Di; Kjærvik, Marit; Østli, Elise Ramleth; Patil, Nilesh; Preobrajenski, Alexei; Andrew Evans, D.; Breiby, Dag W.; Trinh, Thuat T.; Wells, Justin W.

    2018-03-01

    The degradation of the chemotherapy drug 5-fluorouracil by a non-pristine metal surfaces is studied. Using density functional theory, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy we show that the drug is entirely degraded by medical-grade silver surfaces, already at body temperature, and that all of the fluorine has left the molecule, presumably as HF. Remarkably, this degradation is even more severe than that reported previously for 5-fluorouracil on a pristine monocrystalline silver surface (in which case 80% of the drug reacted at body temperature) [1]. We conclude that the observed reaction is due to a reaction pathway, driven by H to F attraction between molecules on the surface, which results in the direct formation of HF; a pathway which is favoured when competing pathways involving reactive Ag surface sites are made unavailable by environmental contamination. Our measurements indicate that realistically cleaned, non-pristine silver alloys, which are typically used in medical applications, can result in severe degradation of 5-fluorouracil, with the release of HF - a finding which may have important implications for the handling of chemotherapy drugs.

  11. Modern thermokarst lake dynamics in the continuous permafrost zone, northern Seward Peninsula, Alaska

    Science.gov (United States)

    Jones, Benjamin M.; Grosse, G.; Arp, C.D.; Jones, M.C.; Walter, Anthony K.M.; Romanovsky, V.E.

    2011-01-01

    Quantifying changes in thermokarst lake extent is of importance for understanding the permafrost-related carbon budget, including the potential release of carbon via lake expansion or sequestration as peat in drained lake basins. We used high spatial resolution remotely sensed imagery from 1950/51, 1978, and 2006/07 to quantify changes in thermokarst lakes for a 700 km2 area on the northern Seward Peninsula, Alaska. The number of water bodies larger than 0.1 ha increased over the entire observation period (666 to 737 or +10.7%); however, total surface area decreased (5,066 ha to 4,312 ha or -14.9%). This pattern can largely be explained by the formation of remnant ponds following partial drainage of larger water bodies. Thus, analysis of large lakes (>40 ha) shows a decrease of 24% and 26% in number and area, respectively, differing from lake changes reported from other continuous permafrost regions. Thermokarst lake expansion rates did not change substantially between 1950/51 and 1978 (0.35 m/yr) and 1978 and 2006/07 (0.39 m/yr). However, most lakes that drained did expand as a result of surface permafrost degradation before lateral drainage. Drainage rates over the observation period were stable (2.2 to 2.3 per year). Thus, analysis of decadal-scale, high spatial resolution imagery has shown that lake drainage in this region is triggered by lateral breaching and not subterranean infiltration. Future research should be directed toward better understanding thermokarst lake dynamics at high spatial and temporal resolution as these systems have implications for landscape-scale hydrology and carbon budgets in thermokarst lake-rich regions in the circum-Arctic.

  12. Present Permafrost Thaw in Central Yakutia, North-East Siberia: Surficial Geology and Hydrology Evidence

    Science.gov (United States)

    Czerniawska, Jolanta; Chlachula, Jiri

    2017-04-01

    Current climate change in the high-latitudes of Eurasia is a generally accepted phenomenon characterized by increased annual temperature values and marked weather anomalies observed in the sub-polar and polar regions. In the northern and NE Siberia, this trend of the MAT rise, documented particularly over the last three decades, is believed to account for the territorial lowland as well as insular mountain frozen ground thaw that in turn has triggered ecosystem feedbacks on the local as well as regional scales. In the northern regions of Yakutia, this is principally witnessed by accelerated near-surface dynamics of seasonally activated de-freezing grounds and inter-linked geomorphic and hydrological actions affecting large-scale tundra landscape settings. In the southern and central taiga-forest areas with perennial alpine and continuous permafrost conditions, respectively, an increased depth of the seasonally melted top-soil layers has become evident accompanied by thermokarst lake expansion and ground surface collapsing. Some cryogenic depressions generated from small gullies over the past decades eloquently demonstrate the intensity and scales of the current permafrost degradation in the Siberian North. The fluvial discharge is most dynamic in late spring to mid-summer because of the cumulative effect of snow-melting because of a high solar radiation and short intervals of torrential rains. Yet, the climate-change-dependent and most active geomorphic agent is the accelerated permafrost thaw seen in landslides and tundra-forest cover decay due to a higher water table. Numerous preserved biotic fossiliferous records Pleistocene and early Holocene in age are being exposed in this process providing unique palaeoecology evidence at particular sites. These climate-generated processes have mostly highly negative effects to the natural habitats (migratory animal routes and riverine biota due to an earlier ice-melting) as well as the local settlement communities

  13. New Method to Characterize Degradation of First Surface Aluminum Reflectors: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Sutter, F.; Heller, P.; Meyen, S.; Pitz-Paal, R.; Kennedy, C.; Fernandez-Garcia, A.; Schmucker, M.

    2010-10-01

    This paper reports the development of a new optical instrument capable of characterizing the aging process of enhanced first surface aluminum reflectors for concentrating solar power (CSP) application. Samples were exposed outdoors at different sites and in accelerated exposure tests. All samples exposed outdoors showed localized corrosion spots. Degradation originated from points of damage in the protective coating, but propagated underneath the protective coating. The degraded samples were analyzed with a microscope and with a newly designed space-resolved specular reflectometer (SR)2 that is capable of optically detecting and characterizing the corrosion spots. The device measures the specular reflectance at three acceptance angles and the wavelengths with spatial resolution using a digital camera's CMOS sensor. It can be used to measure the corrosion growth rate during outdoor and accelerated exposure tests. These results will allow a correlation between the degraded mirror surface and its specular reflectance.

  14. Degradation-by-design: Surface modification with functional substrates that enhance the enzymatic degradation of carbon nanotubes.

    Science.gov (United States)

    Sureshbabu, Adukamparai Rajukrishnan; Kurapati, Rajendra; Russier, Julie; Ménard-Moyon, Cécilia; Bartolini, Isacco; Meneghetti, Moreno; Kostarelos, Kostas; Bianco, Alberto

    2015-12-01

    Biodegradation of carbon-based nanomaterials has been pursued intensively in the last few years, as one of the most crucial issues for the design of safe, clinically relevant conjugates for biomedical applications. In this paper it is demonstrated that specific functional molecules can enhance the catalytic activity of horseradish peroxidase (HRP) and xanthine oxidase (XO) for the degradation of carbon nanotubes. Two different azido coumarins and one cathecol derivative are linked to multi-walled carbon nanotubes (MWCNTs). These molecules are good reducing substrates and strong redox mediators to enhance the catalytic activity of HRP. XO, known to metabolize various molecules mainly in the mammalian liver, including human, was instead used to test the biodegradability of MWCNTs modified with an azido purine. The products of the biodegradation process are characterized by transmission electron microscopy and Raman spectroscopy. The results indicate that coumarin and catechol moieties have enhanced the biodegradation of MWCNTs compared to oxidized nanotubes, likely due to the capacity of these substrates to better interact with and activate HRP. Although azido purine-MWCNTs are degraded less effectively by XO than oxidized nanotubes, the data uncover the importance of XO in the biodegradation of carbon-nanomaterials leading to their better surface engineering for biomedical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Transient thermal effects in Alpine permafrost

    Directory of Open Access Journals (Sweden)

    J. Noetzli

    2009-04-01

    Full Text Available In high mountain areas, permafrost is important because it influences the occurrence of natural hazards, because it has to be considered in construction practices, and because it is sensitive to climate change. The assessment of its distribution and evolution is challenging because of highly variable conditions at and below the surface, steep topography and varying climatic conditions. This paper presents a systematic investigation of effects of topography and climate variability that are important for subsurface temperatures in Alpine bedrock permafrost. We studied the effects of both, past and projected future ground surface temperature variations on the basis of numerical experimentation with simplified mountain topography in order to demonstrate the principal effects. The modeling approach applied combines a distributed surface energy balance model and a three-dimensional subsurface heat conduction scheme. Results show that the past climate variations that essentially influence present-day permafrost temperatures at depth of the idealized mountains are the last glacial period and the major fluctuations in the past millennium. Transient effects from projected future warming, however, are likely larger than those from past climate conditions because larger temperature changes at the surface occur in shorter time periods. We further demonstrate the accelerating influence of multi-lateral warming in steep and complex topography for a temperature signal entering the subsurface as compared to the situation in flat areas. The effects of varying and uncertain material properties (i.e., thermal properties, porosity, and freezing characteristics on the subsurface temperature field were examined in sensitivity studies. A considerable influence of latent heat due to water in low-porosity bedrock was only shown for simulations over time periods of decades to centuries. At the end, the model was applied to the topographic setting of the Matterhorn

  16. Atrazine, triketone herbicides, and their degradation products in sediment, soil and surface water samples in Poland.

    Science.gov (United States)

    Barchanska, Hanna; Sajdak, Marcin; Szczypka, Kornelia; Swientek, Angelika; Tworek, Martyna; Kurek, Magdalena

    2017-01-01

    The aim of this study was to monitor the sediment, soil and surface water contamination with selected popular triketone herbicides (mesotrione (MES) and sulcotrione(SUL)), atrazine (ATR) classified as a possible carcinogen and endocrine disrupting chemical, as well as their degradation products, in Silesia (Poland). Seventeen sediment samples, 24 soil samples, and 64 surface water samples collected in 2014 were studied. After solid-liquid extraction (SLE) and solid phase extraction (SPE), analytes were determined by high-performance liquid chromatography (HPLC) with diode array detection (DAD). Ten years after the withdrawal from the use, ATR was not detected in any of the collected samples; however, its degradation products are still present in 41 % of sediment, 71 % of soil, and 8 % of surface water samples. SUL was determined in 85 % of soil samples; its degradation product (2-chloro-4-(methylosulfonyl) benzoic acid (CMBA)) was present in 43 % of soil samples. In 17 % of sediment samples, CMBA was detected. Triketones were detected occasionally in surface water samples. The chemometric analysis (clustering analysis (CA), single-factor analysis of variance (ANOVA), N-Way ANOVA) was applied to find relations between selected soil and sediment parameters and herbicides concentration. In neither of the studied cases a statistically significant relationship between the concentrations of examined herbicides, their degradation products and soil parameters (organic carbon (OC), pH) was observed.

  17. Degradation of unglazed rough graphite-aluminium solar absorber surfaces in simulated acid and neutral rain

    International Nuclear Information System (INIS)

    Konttinen, P.; Lund, P.D.; Salo, T.

    2005-01-01

    Degradation mechanisms of unglazed solar absorber surfaces based on aluminium substrate were studied. Rough graphite-aluminium surfaces were total-immersion subjected to aerated and de-aerated simulated neutral and acid rain. Test conditions were based on calculated absorber stagnation temperature and global rain acidity measurements. Changes in optical properties, elemental composition and sample mass were examined by spectrometry, energy dispersive X-ray spectrometry and thermogravimetry, respectively. The absorbers exhibited almost no degradation at pH value of 3.5. At pH 5.5 alumina on the surface hydrated significantly degrading the optical properties of the surfaces severely in most cases. Therefore these absorber surfaces can not be recommended to be used in non-glazed applications if they are exposed to rain with pH exceeding ∼ 3.5-4.5. The total-immersion test needs to be developed further as the test results exhibited poor temperature and time dependency thus preventing accurate service lifetime estimates. Still, these tests were useful in determining favourable and non-favourable operating conditions for the absorber surfaces based on aluminium substrate. (author)

  18. Role of ground ice dynamics and ecological feedbacks in recent ice wedge degradation and stabilization

    Science.gov (United States)

    Mark Torre Jorgenson,; Mikhail Kanevskiy,; Yuri Shur,; Natalia Moskalenko,; Dana Brown,; Wickland, Kimberly P.; Striegl, Robert G.; Koch, Joshua C.

    2015-01-01

    Ground ice is abundant in the upper permafrost throughout the Arctic and fundamentally affects terrain responses to climate warming. Ice wedges, which form near the surface and are the dominant type of massive ice in the Arctic, are particularly vulnerable to warming. Yet processes controlling ice wedge degradation and stabilization are poorly understood. Here we quantified ice wedge volume and degradation rates, compared ground ice characteristics and thermal regimes across a sequence of five degradation and stabilization stages and evaluated biophysical feedbacks controlling permafrost stability near Prudhoe Bay, Alaska. Mean ice wedge volume in the top 3 m of permafrost was 21%. Imagery from 1949 to 2012 showed thermokarst extent (area of water-filled troughs) was relatively small from 1949 (0.9%) to 1988 (1.5%), abruptly increased by 2004 (6.3%) and increased slightly by 2012 (7.5%). Mean annual surface temperatures varied by 4.9°C among degradation and stabilization stages and by 9.9°C from polygon center to deep lake bottom. Mean thicknesses of the active layer, ice-poor transient layer, ice-rich intermediate layer, thermokarst cave ice, and wedge ice varied substantially among stages. In early stages, thaw settlement caused water to impound in thermokarst troughs, creating positive feedbacks that increased net radiation, soil heat flux, and soil temperatures. Plant growth and organic matter accumulation in the degraded troughs provided negative feedbacks that allowed ground ice to aggrade and heave the surface, thus reducing surface water depth and soil temperatures in later stages. The ground ice dynamics and ecological feedbacks greatly complicate efforts to assess permafrost responses to climate change.

  19. Role of ground ice dynamics and ecological feedbacks in recent ice wedge degradation and stabilization

    Science.gov (United States)

    Jorgenson, M. T.; Kanevskiy, M.; Shur, Y.; Moskalenko, N.; Brown, D. R. N.; Wickland, K.; Striegl, R.; Koch, J.

    2015-11-01

    Ground ice is abundant in the upper permafrost throughout the Arctic and fundamentally affects terrain responses to climate warming. Ice wedges, which form near the surface and are the dominant type of massive ice in the Arctic, are particularly vulnerable to warming. Yet processes controlling ice wedge degradation and stabilization are poorly understood. Here we quantified ice wedge volume and degradation rates, compared ground ice characteristics and thermal regimes across a sequence of five degradation and stabilization stages and evaluated biophysical feedbacks controlling permafrost stability near Prudhoe Bay, Alaska. Mean ice wedge volume in the top 3 m of permafrost was 21%. Imagery from 1949 to 2012 showed thermokarst extent (area of water-filled troughs) was relatively small from 1949 (0.9%) to 1988 (1.5%), abruptly increased by 2004 (6.3%) and increased slightly by 2012 (7.5%). Mean annual surface temperatures varied by 4.9°C among degradation and stabilization stages and by 9.9°C from polygon center to deep lake bottom. Mean thicknesses of the active layer, ice-poor transient layer, ice-rich intermediate layer, thermokarst cave ice, and wedge ice varied substantially among stages. In early stages, thaw settlement caused water to impound in thermokarst troughs, creating positive feedbacks that increased net radiation, soil heat flux, and soil temperatures. Plant growth and organic matter accumulation in the degraded troughs provided negative feedbacks that allowed ground ice to aggrade and heave the surface, thus reducing surface water depth and soil temperatures in later stages. The ground ice dynamics and ecological feedbacks greatly complicate efforts to assess permafrost responses to climate change.

  20. Degradation state of organic matter in surface sediments from the Beaufort Shelf: a lipid approach

    Science.gov (United States)

    Rontani, J.-F.; Charriere, B.; Petit, M.; Vaultier, F.; Heipieper, H. J.; Link, H.; Chaillou, G.; Sempéré, R.

    2012-03-01

    The lipid content of surface sediments collected on the Beaufort Shelf was examined. Particular attention was given to biotic and abiotic degradation products of sterols and monounsaturated fatty acids. By using sitosterol and campesterol degradation products as tracers of the degradation of terrestrial higher plant inputs and brassicasterol degradation products as tracers of degradation of phytoplanktonic organisms, it could be observed that autoxidation, photooxidation and biodegradation processes act much more intensively on higher plant debris than on phytoplanktonic organisms. Examination of oxidation products of monounsaturated fatty acids showed that photo- and autoxidation processes act more intensively on bacteria than on phytodetritus. Enhanced damages induced by singlet oxygen (transferred from senescent phytoplanktonic cells) in bacteria were attributed to the lack of an adapted antioxidant system in these microorganisms. The strong oxidative stress observed in the sampled sediments resulted in the production of significant amounts of epoxyacids and unusually very high proportions of monounsaturated fatty acids with a trans double bond. The formation of epoxyacids was attributed to peroxygenases (enzymes playing a protective role against the deleterious effects of fatty acid hydroperoxides in vivo), while cis/trans isomerization was probably induced by thiyl radicals produced during the reaction of thiols with hydroperoxides. Our results confirm the important role played by abiotic oxidative processes in the degradation of marine bacteria and do not support the generally expected refractory character of terrigenous material deposited in deltaic systems.

  1. Photocatalytic Performance and Degradation Mechanism of Aspirin by TiO2 through Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Lezhuo Li

    2018-03-01

    Full Text Available In the present work, the photocatalytic performance of P25TiO2 was investigated by means of the degradation of aspirin, while the reaction system was systematically optimized by central composite design (CCD based on the response surface methodology (RSM. In addition, three variables of initial pH value, initial aspirin concentration and P25 concentration were selected to assess the dependence of degradation efficiencies of aspirin. Meanwhile, a predicted model of degradation efficiency was estimated and checked using analysis of variance (ANOVA. The results indicated that the PC removal of aspirin by P25 was significantly influenced by all these variables in descending order as follows: P25 concentration > initial aspirin concentration > initial pH value. Moreover, the parameters were optimized by the CCD method. Under the conditions of an initial pH value of 5, initial aspirin concentration of 10 mg/L and P25 concentration of 50 mg/L, the degradation efficiency of aspirin was 98.9%with 60 min of Xenon lamp irradiation. Besides, based on the liquid chromatography-mass spectrometry measurements, two main PC degradation pathways of aspirin by TiO2 were deduced and the tentative degradation mechanism was also proposed.

  2. Air–surface exchange of gaseous mercury over permafrost soil: an investigation at a high-altitude (4700 m a.s.l. and remote site in the central Qinghai–Tibet Plateau

    Directory of Open Access Journals (Sweden)

    Z. Ci

    2016-11-01

    Full Text Available The pattern of air–surface gaseous mercury (mainly Hg(0 exchange in the Qinghai–Tibet Plateau (QTP may be unique because this region is characterized by low temperature, great temperature variation, intensive solar radiation, and pronounced freeze–thaw process of permafrost soils. However, the air–surface Hg(0 flux in the QTP is poorly investigated. In this study, we performed field measurements and controlled field experiments with dynamic flux chambers technique to examine the flux, temporal variation and influencing factors of air–surface Hg(0 exchange at a high-altitude (4700 m a.s.l. and remote site in the central QTP. The results of field measurements showed that surface soils were the net emission source of Hg(0 in the entire study (2.86 ng m−2 h−1 or 25.05 µg m−2 yr−1. Hg(0 flux showed remarkable seasonality with net high emission in the warm campaigns (June 2014: 4.95 ng m−2 h−1; September 2014: 5.16 ng m−2 h−1; and May–June 2015: 1.95 ng m−2 h−1 and net low deposition in the winter campaign (December 2014: −0.62 ng m−2 h−1 and also showed a diurnal pattern with emission in the daytime and deposition in nighttime, especially on days without precipitation. Rainfall events on the dry soils induced a large and immediate increase in Hg(0 emission. Snowfall events did not induce the pulse of Hg(0 emission, but snowmelt resulted in the immediate increase in Hg(0 emission. Daily Hg(0 fluxes on rainy or snowy days were higher than those of days without precipitation. Controlled field experiments suggested that water addition to dry soils significantly increased Hg(0 emission both on short (minutes and relatively long (hours timescales, and they also showed that UV radiation was primarily attributed to Hg(0 emission in the daytime. Our findings imply that a warm climate and environmental change could facilitate Hg release from the permafrost terrestrial ecosystem

  3. Deglacial remobilization of permafrost carbon to sediments along the East Siberian Arctic Seas

    Science.gov (United States)

    Martens, J.; Wild, B.; Bröder, L.; Andersson, A.; Pearce, C.; O'Regan, M.; Jakobsson, M.; Tesi, T.; Muschitiello, F.; Sköld, M.; Semiletov, I. P.; Dudarev, O.; Gustafsson, O.

    2017-12-01

    Current climate change is expected to thaw large quantities of permafrost carbon (PF-C) and expose it to degradation which emits greenhouse gases (i.e. CO2 and CH4). Warming causes a gradual deepening of the seasonally thawed active layer surface of permafrost soils, but also the abrupt collapse of deeper Ice Complex Deposits (ICD), especially along Siberian coastlines. It was recently hypothesized that past warming already induced large-scale permafrost degradation after the last glacial, which ultimately amplified climate forcing. We here assess the mobilization of PF-C to East Siberian Arctic Sea sediments during these warming periods. We perform source apportionment using bulk carbon isotopes (ΔΔ14C, δ13C) together with terrestrial biomarkers (CuO-derived lignin phenols) as indicators for PF-C transfer. We apply these techniques to sediment cores (SWERUS-L2) from the Chukchi Sea (4-PC1) and the southern Lomonosov Ridge (31-PC1). We found that PF-C fluxes during the Bølling-Allerød warming (14.7 to 12.7 cal ka BP), the Younger Dryas cooling (12.7 to 11.7 cal ka BP) and the early Holocene warming (until 11 cal ka BP) were overall higher than mid and late Holocene fluxes. In the Chukchi Sea, PF-C burial was 2x higher during the deglaciation (7.2 g m-2 a-1) than in the mid and late Holocene (3.6 g m-2 a-1), and ICD were the dominant source of PF-C (79.1%). Smaller fractions originated from the active layer (9.1%) and marine sources (11.7%). We conclude that thermo-erosion of ICD released large amounts of PF-C to the Chukchi Sea, likely driven by climate warming and the deglacial sea level rise. This contrasts to earlier analyses of Laptev Sea sediments where active layer material from river transport dominated the carbon flux. Preliminary data on lignin phenol concentrations of Lomonosov Ridge sediments suggest that the postglacial remobilization of PF-C was one order of magnitude higher (10x) than during both the preceding glacial and the subsequent Holocene

  4. Molecular weight-dependent degradation and drug release of surface-eroding poly(ethylene carbonate).

    Science.gov (United States)

    Bohr, Adam; Wang, Yingya; Harmankaya, Necati; Water, Jorrit J; Baldursdottír, Stefania; Almdal, Kristoffer; Beck-Broichsitter, Moritz

    2017-06-01

    Poly(ethylene carbonate) (PEC) is a unique biomaterial showing significant potential for controlled drug delivery applications. The current study investigated the impact of the molecular weight on the biological performance of drug-loaded PEC films. Following the preparation and thorough physicochemical characterization of diverse PEC (molecular weights: 85, 110, 133, 174 and 196kDa), the degradation and drug release behavior of rifampicin- and bovine serum albumin-loaded PEC films was investigated in vitro (in the presence and absence of cholesterol esterase), in cell culture (RAW264.7 macrophages) and in vivo (subcutaneous implantation in rats). All investigated samples degraded by means of surface erosion (mass loss, but constant molecular weight), which was accompanied by a predictable, erosion-controlled drug release pattern. Accordingly, the obtained in vitro degradation half-lives correlated well with the observed in vitro half-times of drug delivery (R 2 =0.96). Here, the PEC of the highest molecular weight resulted in the fastest degradation/drug release. When incubated with macrophages or implanted in animals, the degradation rate of PEC films superimposed the results of in vitro incubations with cholesterol esterase. Interestingly, SEM analysis indicated a distinct surface erosion process for enzyme-, macrophage- and in vivo-treated polymer films in a molecular weight-dependent manner. Overall, the molecular weight of surface-eroding PEC was identified as an essential parameter to control the spatial and temporal on-demand degradation and drug release from the employed delivery system. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Hydrogeology, Chemical and Microbial Activity Measurement Through Deep Permafrost

    Science.gov (United States)

    Stotler, R.L.; Frape, S.K.; Freifeld, B.M.; Holden, B.; Onstott, T.C.; Ruskeeniemi, T.; Chan, E.

    2011-01-01

    Little is known about hydrogeochemical conditions beneath thick permafrost, particularly in fractured crystalline rock, due to difficulty in accessing this environment. The purpose of this investigation was to develop methods to obtain physical, chemical, and microbial information about the subpermafrost environment from a surface-drilled borehole. Using a U-tube, gas and water samples were collected, along with temperature, pressure, and hydraulic conductivity measurements, 420 m below ground surface, within a 535 m long, angled borehole at High Lake, Nunavut, Canada, in an area with 460-m-thick permafrost. Piezometric head was well above the base of the permafrost, near land surface. Initial water samples were contaminated with drill fluid, with later samples values ???5??? lower than the local surface water. The fluid isotopic composition was affected by the permafrost-formation process. Nonbacteriogenic CH4 was present and the sample location was within methane hydrate stability field. Sampling lines froze before uncontaminated samples from the subpermafrost environment could be obtained, yet the available time to obtain water samples was extended compared to previous studies. Temperature measurements collected from a distributed temperature sensor indicated that this issue can be overcome easily in the future. The lack of methanogenic CH4 is consistent with the high sulfate concentrations observed in cores. The combined surface-drilled borehole/U-tube approach can provide a large amount of physical, chemical, and microbial data from the subpermafrost environment with few, controllable, sources of contamination. ?? 2010 The Author(s). Journal compilation ?? 2010 National Ground Water Association.

  6. The influence of vegetation and soil characteristics on active-layer thickness of permafrost soils in boreal forest.

    Science.gov (United States)

    Fisher, James P; Estop-Aragonés, Cristian; Thierry, Aaron; Charman, Dan J; Wolfe, Stephen A; Hartley, Iain P; Murton, Julian B; Williams, Mathew; Phoenix, Gareth K

    2016-09-01

    Carbon release from thawing permafrost soils could significantly exacerbate global warming as the active-layer deepens, exposing more carbon to decay. Plant community and soil properties provide a major control on this by influencing the maximum depth of thaw each summer (active-layer thickness; ALT), but a quantitative understanding of the relative importance of plant and soil characteristics, and their interactions in determine ALTs, is currently lacking. To address this, we undertook an extensive survey of multiple vegetation and edaphic characteristics and ALTs across multiple plots in four field sites within boreal forest in the discontinuous permafrost zone (NWT, Canada). Our sites included mature black spruce, burned black spruce and paper birch, allowing us to determine vegetation and edaphic drivers that emerge as the most important and broadly applicable across these key vegetation and disturbance gradients, as well as providing insight into site-specific differences. Across sites, the most important vegetation characteristics limiting thaw (shallower ALTs) were tree leaf area index (LAI), moss layer thickness and understory LAI in that order. Thicker soil organic layers also reduced ALTs, though were less influential than moss thickness. Surface moisture (0-6 cm) promoted increased ALTs, whereas deeper soil moisture (11-16 cm) acted to modify the impact of the vegetation, in particular increasing the importance of understory or tree canopy shading in reducing thaw. These direct and indirect effects of moisture indicate that future changes in precipitation and evapotranspiration may have large influences on ALTs. Our work also suggests that forest fires cause greater ALTs by simultaneously decreasing multiple ecosystem characteristics which otherwise protect permafrost. Given that vegetation and edaphic characteristics have such clear and large influences on ALTs, our data provide a key benchmark against which to evaluate process models used to predict

  7. Degradation and stabilization of ice wedges: Implications for assessing risk of thermokarst in northern Alaska

    Science.gov (United States)

    Kanevskiy, Mikhail; Shur, Yuri; Jorgenson, Torre; Brown, Dana R. N.; Moskalenko, Nataliya; Brown, Jerry; Walker, Donald A.; Raynolds, Martha K.; Buchhorn, Marcel

    2017-11-01

    Widespread degradation of ice wedges has been observed during the last decades in numerous areas within the continuous permafrost zone of Eurasia and North America. To study ice-wedge degradation, we performed field investigations at Prudhoe Bay and Barrow in northern Alaska during 2011-2016. In each study area, a 250-m transect was established with plots representing different stages of ice-wedge degradation/stabilization. Field work included surveying ground- and water-surface elevations, thaw-depth measurements, permafrost coring, vegetation sampling, and ground-based LiDAR scanning. We described cryostratigraphy of frozen soils and stable isotope composition, analyzed environmental characteristics associated with ice-wedge degradation and stabilization, evaluated the vulnerability and resilience of ice wedges to climate change and disturbances, and developed new conceptual models of ice-wedge dynamics that identify the main factors affecting ice-wedge degradation and stabilization and the main stages of this quasi-cyclic process. We found significant differences in the patterns of ice-wedge degradation and stabilization between the two areas, and the patterns were more complex than those previously described because of the interactions of changing topography, water redistribution, and vegetation/soil responses that can interrupt or reinforce degradation. Degradation of ice wedges is usually triggered by an increase in the active-layer thickness during exceptionally warm and wet summers or as a result of flooding or disturbance. Vulnerability of ice wedges to thermokarst is controlled by the thickness of the intermediate layer of the upper permafrost, which overlies ice wedges and protects them from thawing. In the continuous permafrost zone, degradation of ice wedges rarely leads to their complete melting; and in most cases wedges eventually stabilize and can then resume growing, indicating a somewhat cyclic and reversible process. Stabilization of ice wedges

  8. Variability in the sensitivity among model simulations of permafrost and carbon dynamics in the permafrost region between 1960 and 2009

    Science.gov (United States)

    McGuire, A. David; Koven, Charles; Lawrence, David M.; Clein, Joy S.; Xia, Jiangyang; Beer, Christian; Burke, Eleanor J.; Chen, Guangsheng; Chen, Xiaodong; Delire, Christine; Jafarov, Elchin; MacDougall, Andrew H.; Marchenko, Sergey S.; Nicolsky, Dmitry J.; Peng, Shushi; Rinke, Annette; Saito, Kazuyuki; Zhang, Wenxin; Alkama, Ramdane; Bohn, Theodore J.; Ciais, Philippe; Decharme, Bertrand; Ekici, Altug; Gouttevin, Isabelle; Hajima, Tomohiro; Hayes, Daniel J.; Ji, Duoying; Krinner, Gerhard; Lettenmaier, Dennis P.; Luo, Yiqi; Miller, Paul A.; Moore, John C.; Romanovsky, Vladimir; Schädel, Christina; Schaefer, Kevin; Schuur, Edward A.G.; Smith, Benjamin; Sueyoshi, Tetsuo; Zhuang, Qianlai

    2016-01-01

    A significant portion of the large amount of carbon (C) currently stored in soils of the permafrost region in the Northern Hemisphere has the potential to be emitted as the greenhouse gases CO2and CH4 under a warmer climate. In this study we evaluated the variability in the sensitivity of permafrost and C in recent decades among land surface model simulations over the permafrost region between 1960 and 2009. The 15 model simulations all predict a loss of near-surface permafrost (within 3 m) area over the region, but there are large differences in the magnitude of the simulated rates of loss among the models (0.2 to 58.8 × 103 km2 yr−1). Sensitivity simulations indicated that changes in air temperature largely explained changes in permafrost area, although interactions among changes in other environmental variables also played a role. All of the models indicate that both vegetation and soil C storage together have increased by 156 to 954 Tg C yr−1between 1960 and 2009 over the permafrost region even though model analyses indicate that warming alone would decrease soil C storage. Increases in gross primary production (GPP) largely explain the simulated increases in vegetation and soil C. The sensitivity of GPP to increases in atmospheric CO2 was the dominant cause of increases in GPP across the models, but comparison of simulated GPP trends across the 1982–2009 period with that of a global GPP data set indicates that all of the models overestimate the trend in GPP. Disturbance also appears to be an important factor affecting C storage, as models that consider disturbance had lower increases in C storage than models that did not consider disturbance. To improve the modeling of C in the permafrost region, there is the need for the modeling community to standardize structural representation of permafrost and carbon dynamics among models that are used to evaluate the permafrost C feedback and for the modeling and observational communities to

  9. Impact of Black Dust Pollution on Permafrost Temperature Regime in Pechora Basin

    Science.gov (United States)

    Khilimonyuk, V.; Pustovoit, G.; Filatova, M.

    2011-12-01

    Pechora Coal basin locates in North- Easter part of Europe within permafrost zone. The coal mining and post processing lead to emission of black dust (BD) and pollution of Earth surface. The scale of snow pollution surrounding Vorkuta city reaches to 260 g/sq.m of dust that is about 1000 ppmm BD concentration in snow before melting period. Such a large concentration of dust reduces snow reflectivity (Warren and Wiscombe, 1980; Chýlek et al., 1983,Gorbacheva, 1984, Zender et al, 2010) and can thereby trigger albedo feedbacks. The goal of this study is to evaluate the role of dirty surface albedo in the observed changing of permafrost regime in this basin. Two key sites: Workuta (North permafrost zone) and Inta (South permafrost zone) areas were selected for this study. For each site the zoning of territory by typical conditions of permafrost formation was performed. For the selected typical landscapes 1-D vertical heat transfer model coupled with the surface radiation-thermal balance equation at topsoil was simulated. The simulation was performed for the soil profile of 20 m depth during 20 years period with periodical input data at dirty surface averaged on monthly base. The initial measured not disturbed soil temperature profile was used for assessment the soil thermal property for the given landscape and natural surface radiation-thermal balance. The annual cycle of albedo change for dirty surface was taken from experimental measurement (Gorbacheva, 1984) for both sites as the function of the distance from the dust source. The simulation results next were used for mapping the vulnerability of permafrost thermal regime due to black dust pollution. Generally the simulation results show that South permafrost zone with mean temperature of permafrost (-0.5 -0.1C) is more vulnerable to albedo change than North permafrost zone with mean temperature (-2.5 -2C) for the same order of dust impact on albedo.

  10. Collapsing permafrost coasts in the Arctic

    Science.gov (United States)

    Fritz, Michael; Lantuit, Hugues

    2017-04-01

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

  11. Aspirin degradation in surface-charged TEMPO-oxidized mesoporous crystalline nanocellulose.

    Science.gov (United States)

    Carlsson, Daniel O; Hua, Kai; Forsgren, Johan; Mihranyan, Albert

    2014-01-30

    TEMPO-mediated surface oxidation of mesoporous highly crystalline Cladophora cellulose was used to introduce negative surface charges onto cellulose nanofibrils without significantly altering other structural characteristics. This enabled the investigation of the influence of mesoporous nanocellulose surface charges on aspirin chemical stability to be conducted. The negative surface charges (carboxylate content 0.44±0.01 mmol/g) introduced on the mesoporous crystalline nanocellulose significantly accelerated aspirin degradation, compared to the starting material which had significantly less surface charge (0.06±0.01 mmol/g). This effect followed from an increased aspirin amorphisation ability in mesopores of the oxidized nanocellulose. These results highlight the importance of surface charges in formulating nanocellulose for drug delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. The Ecological Situation in the Russian Arctic Permafrost Zone

    Directory of Open Access Journals (Sweden)

    Petrov Sergei

    2016-01-01

    Full Text Available The paper describes innovative approaches to ensure environmental safety in the production of hydrocarbon material in a permafrost zone. Studies the anthropogenic environmental factors, climatic and geographical and geological conditions of Purovskiy district of Yamalo-Nenets Autonomous Area (YaNAO. We consider the chemical characteristics of wastewater discharged into surface water objects, polluting emissions into the atmosphere. The conclusions of the environmental situation in Purovskiy and Ustpurovsk-Tazovskiy permafrost areas. Calculate the concentration of pollutants in the control section of the water object and the maximum ground-level concentrations of pollutants in the atmospheric air. The conclusions about the exceeding the maximum permissible concentration (MPC in the atmospheric air for solids, carbon monoxide, nitrogen dioxide. Was examined the climatic conditions of the Far North. Correlational analysis was performed between human factors and temperature conditions of the northern territories, as well as between the climate and natural features cryological and disturbed permafrost soils.

  13. Historical and Possible Future Changes in Permafrost and Active Layer Thickness in Alaska: Implications to Landscape Changes and Permafrost Carbon Pool.

    Science.gov (United States)

    Marchenko, S. S.; Helene, G.; Euskirchen, E. S.; Breen, A. L.; McGuire, D.; Rupp, S. T.; Romanovsky, V. E.; Walsh, J. E.

    2017-12-01

    The Soil Temperature and Active Layer Thickness (ALT) Gridded Data was developed to quantify the nature and rate of permafrost degradation and its impact on ecosystems, infrastructure, CO2 and CH4 fluxes and net C storage following permafrost thaw across Alaska. To develop this database, we used the process-based permafrost dynamics model GIPL2 developed in the Geophysical Institute Permafrost Lab, UAF and which is the permafrost module of the Integrated Ecosystem Model (IEM) for Alaska and Northwest Canada. The climate forcing data for simulations were developed by the Scenarios Network for Alaska and Arctic Planning (SNAP, http://www.snap.uaf.edu/). These data are based on the historical CRU3.1 data set for the retrospective analysis period (1901-2009) and the five model averaged data were derived from the five CMIP5/AR5 IPCC Global Circulation Models that performed the best in Alaska and other northern regions: NCAR-CCSM4, GFDL-CM3, GISS-E2-R, IPSL-CM5A-LR, MRI-CGCM3. A composite of all five-model outputs for the RCP4.5 and RCP8.5 were used in these particular permafrost dynamics simulations. Data sets were downscaled to a 771 m resolution, using the Parameter-elevation Regressions on Independent Slopes Model (PRISM) climatology. Additional input data (snow characteristics, soil thermal properties, soil water content, organic matter accumulation or its loss due to fire, etc.) came from the Terrestrial Ecosystem Model (TEM) and the ALFRESCO (ALaska FRame-based EcoSystem COde) model simulations. We estimated the dynamics of permafrost temperature, active layer thickness, area occupied by permafrost, and volume of seasonally thawed soils within the 4.75 upper meters (original TEM soil column) across the Alaska domain. Simulations of future changes in permafrost indicate that, by the end of the 21st century, late-Holocene permafrost in Alaska will be actively thawing at all locations and that some Late Pleistocene carbon-rich peatlands underlain by permafrost will

  14. Shifts of tundra bacterial and archaeal communities along a permafrost thaw gradient in Alaska.

    Science.gov (United States)

    Deng, Jie; Gu, Yunfu; Zhang, Jin; Xue, Kai; Qin, Yujia; Yuan, Mengting; Yin, Huaqun; He, Zhili; Wu, Liyou; Schuur, Edward A G; Tiedje, James M; Zhou, Jizhong

    2015-01-01

    Understanding the response of permafrost microbial communities to climate warming is crucial for evaluating ecosystem feedbacks to global change. This study investigated soil bacterial and archaeal communities by Illumina MiSeq sequencing of 16S rRNA gene amplicons across a permafrost thaw gradient at different depths in Alaska with thaw progression for over three decades. Over 4.6 million passing 16S rRNA gene sequences were obtained from a total of 97 samples, corresponding to 61 known classes and 470 genera. Soil depth and the associated soil physical-chemical properties had predominant impacts on the diversity and composition of the microbial communities. Both richness and evenness of the microbial communities decreased with soil depth. Acidobacteria, Verrucomicrobia, Alpha- and Gamma-Proteobacteria dominated the microbial communities in the upper horizon, whereas abundances of Bacteroidetes, Delta-Proteobacteria and Firmicutes increased towards deeper soils. Effects of thaw progression were absent in microbial communities in the near-surface organic soil, probably due to greater temperature variation. Thaw progression decreased the abundances of the majority of the associated taxa in the lower organic soil, but increased the abundances of those in the mineral soil, including groups potentially involved in recalcitrant C degradation (Actinomycetales, Chitinophaga, etc.). The changes in microbial communities may be related to altered soil C sources by thaw progression. Collectively, this study revealed different impacts of thaw in the organic and mineral horizons and suggests the importance of studying both the upper and deeper soils while evaluating microbial responses to permafrost thaw. © 2014 John Wiley & Sons Ltd.

  15. Molecular weight-dependent degradation and drug release of surface-eroding poly(ethylene carbonate)

    DEFF Research Database (Denmark)

    Bohr, Adam; Wang, Yingya; Harmankaya, Necati

    2017-01-01

    Poly(ethylene carbonate) (PEC) is a unique biomaterial showing significant potential for controlled drug delivery applications. The current study investigated the impact of the molecular weight on the biological performance of drug-loaded PEC films. Following the preparation and thorough...... physicochemical characterization of diverse PEC (molecular weights: 85, 110, 133, 174 and 196 kDa), the degradation and drug release behavior of rifampicin- and bovine serum albumin-loaded PEC films was investigated in vitro (in the presence and absence of cholesterol esterase), in cell culture (RAW264.......7 macrophages) and in vivo (subcutaneous implantation in rats). All investigated samples degraded by means of surface erosion (mass loss, but constant molecular weight), which was accompanied by a predictable, erosion-controlled drug release pattern. Accordingly, the obtained in vitro degradation half...

  16. Circumpolar Active-Layer Permafrost System (CAPS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Circumpolar Active-Layer Permafrost System (CAPS) contains over 100 data sets pertaining to permafrost and frozen ground topics. It also contains detailed...

  17. Present and LGM permafrost from climate simulations: contribution of statistical downscaling

    Directory of Open Access Journals (Sweden)

    G. Levavasseur

    2011-11-01

    Full Text Available We quantify the agreement between permafrost distributions from PMIP2 (Paleoclimate Modeling Intercomparison Project climate models and permafrost data. We evaluate the ability of several climate models to represent permafrost and assess the variability between their results.

    Studying a heterogeneous variable such as permafrost implies conducting analysis at a smaller spatial scale compared with climate models resolution. Our approach consists of applying statistical downscaling methods (SDMs on large- or regional-scale atmospheric variables provided by climate models, leading to local-scale permafrost modelling. Among the SDMs, we first choose a transfer function approach based on Generalized Additive Models (GAMs to produce high-resolution climatology of air temperature at the surface. Then we define permafrost distribution over Eurasia by air temperature conditions. In a first validation step on present climate (CTRL period, this method shows some limitations with non-systematic improvements in comparison with the large-scale fields.

    So, we develop an alternative method of statistical downscaling based on a Multinomial Logistic GAM (ML-GAM, which directly predicts the occurrence probabilities of local-scale permafrost. The obtained permafrost distributions appear in a better agreement with CTRL data. In average for the nine PMIP2 models, we measure a global agreement with CTRL permafrost data that is better when using ML-GAM than when applying the GAM method with air temperature conditions. In both cases, the provided local information reduces the variability between climate models results. This also confirms that a simple relationship between permafrost and the air temperature only is not always sufficient to represent local-scale permafrost.

    Finally, we apply each method on a very different climate, the Last Glacial Maximum (LGM time period, in order to quantify the ability of climate models to represent LGM

  18. Isotropic thaw subsidence in undisturbed permafrost landscapes

    Science.gov (United States)

    Shiklomanov, Nikolay I.; Streletskiy, Dmitry A.; Little, Jonathon D.; Nelson, Frederick E.

    2013-12-01

    in undisturbed terrain within some regions of the Arctic reveal limited correlation between increasing air temperature and the thickness of the seasonally thawed layer above ice-rich permafrost. Here we describe landscape-scale, thaw-induced subsidence lacking the topographic contrasts associated with thermokarst terrain. A high-resolution, 11 year record of temperature and vertical movement at the ground surface from contrasting physiographic regions of northern Alaska, obtained with differential global positioning systems technology, indicates that thaw of an ice-rich layer at the top of permafrost has produced decimeter-scale subsidence extending over the entire landscapes. Without specialized observation techniques the subsidence is not apparent to observers at the surface. This "isotropic thaw subsidence" explains the apparent stability of active layer thickness records from some landscapes of northern Alaska, despite warming near-surface air temperatures. Integrated over extensive regions, it may be responsible for thawing large volumes of carbon-rich substrate and could have negative impacts on infrastructure.

  19. Amoxicillin degradation from contaminated water by solar photocatalysis using response surface methodology (RSM).

    Science.gov (United States)

    Moosavi, Fatemeh Sadat; Tavakoli, Touraj

    2016-11-01

    In this study, the solar photocatalytic process in a pilot plant with compound parabolic collectors (CPCs) was performed for amoxicillin (AMX) degradation, an antibiotic widely used in the world. The response surface methodology (RSM) based on Box-Behnken statistical experiment design was used to optimize independent variables, namely TiO 2 dosage, antibiotic initial concentration, and initial pH. The results showed that AMX degradation efficiency affected by positive or negative effect of variables and their interactions. The TiO 2 dosage, pH, and interaction between AMX initial concentration and TiO 2 dosage exhibited a synergistic effect, while the linear and quadratic term of AMX initial concentration and pH showed antagonistic effect in the process response. Response surface and contour plots were used to perform process optimization. The optimum conditions found in this regard were TiO 2 dosage = 1.5 g/L, AMX initial concentration = 17 mg/L, and pH = 9.5 for AMX degradation under 240 min solar irradiation. The photocatalytic degradation of AMX after 34.95 kJ UV /L accumulated UV energy per liter of solution was 84.12 % at the solar plant.

  20. In situ nuclear magnetic resonance response of permafrost and active layer soil in boreal and tundra ecosystems

    Science.gov (United States)

    Kass, Mason A.; Irons, Trevor P; Minsley, Burke J.; Pastick, Neal J.; Brown, Dana R N; Wylie, Bruce K.

    2017-01-01

    Characterization of permafrost, particularly warm and near-surface permafrost which can contain significant liquid water, is critical to understanding complex interrelationships with climate change, ecosystems, and disturbances such as wildfires. Understanding the vulnerability and resilience of permafrost requires an interdisciplinary approach, relying on (for example) geophysical investigations, ecological characterization, direct observations, remote sensing, and more. As part of a multi-year investigation into the impacts of wildfires to permafrost, we have collected in situ measurements of the nuclear magnetic resonance (NMR) response of active layer and permafrost in a variety of soil conditions, types, and saturations. In this paper, we summarize the NMR data and present quantitative relationships between active layer and permafrost liquid water content and pore sizes. Through statistical analyses and synthetic freezing simulations, we also demonstrate that borehole NMR can image the nucleation of ice within soil pore spaces.

  1. Forest fire effects on slopes formed in ice-rich permafrost soils: Mackenzie Valley, Northwest Territories

    Energy Technology Data Exchange (ETDEWEB)

    Savigny, W. [Bruce Geotechnical Consultants Inc., Vancouver, BC (Canada); Logue, C. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Geological Sciences; MacInnes, K. [Department of Indian Affairs and Northern Development, Yellowknife, NT (Canada)

    1995-12-31

    The impact of fires on the ground thermal regime and the related development of thaw generated excess pore pressures in the degrading permafrost, some in the immediate vicinity of the interprovincial pipeline in the Northwest Territories, were modeled in an attempt to demonstrate that the observed slope instability was a predictable consequence of sudden and severe ground surface disturbance. A one-dimensional finite model was used to simulate ground temperatures both before and after the fires. Excess pore pressures related to the rate of thaw were determined and used in a limit equilibrium analysis. Results indicated that a critical factor of safety for shallow planar instability in fine-grained ice-rich permafrost soils comprising natural slopes developed within a few weeks after the fires. Instability was predicted to occur on slopes as low as 10 degrees, although field observations suggested the extent of instability would be naturally limited by stratigraphic variations. It was suggested that this method of rapid identification of `values at risk` was an attractive technique in managing forests in areas exposed to fire hazards, especially in the face of dwindling fire-fighting resources. 15 refs., 3 tabs., 6 figs.

  2. Subsurface flow pathway dynamics in the active layer of coupled permafrost-hydrogeological systems under seasonal and annual temperature variability.

    Science.gov (United States)

    Frampton, Andrew

    2017-04-01

    There is a need for improved understanding of the mechanisms controlling subsurface solute transport in the active layer in order to better understand permafrost-hydrological-carbon feedbacks, in particular with regards to how dissolved carbon is transported in coupled surface and subsurface terrestrial arctic water systems under climate change. Studying solute transport in arctic systems is also relevant in the context of anthropogenic pollution which may increase due to increased activity in cold region environments. In this contribution subsurface solute transport subject to ground surface warming causing permafrost thaw and active layer change is studied using a physically based model of coupled cryotic and hydrogeological flow processes combined with a particle tracking method. Changes in subsurface water flows and solute transport travel times are analysed for different modelled geological configurations during a 100-year warming period. Results show that for all simulated cases, the minimum and mean travel times increase non-linearly with warming irrespective of geological configuration and heterogeneity structure. The timing of the start of increase in travel time depends on heterogeneity structure, combined with the rate of permafrost degradation that also depends on material thermal and hydrogeological properties. These travel time changes are shown to depend on combined warming effects of increase in pathway length due to deepening of the active layer, reduced transport velocities due to a shift from horizontal saturated groundwater flow near the surface to vertical water percolation deeper into the subsurface, and pathway length increase and temporary immobilization caused by cryosuction-induced seasonal freeze cycles. The impact these change mechanisms have on solute and dissolved substance transport is further analysed by integrating pathway analysis with a Lagrangian approach, incorporating considerations for both dissolved organic and inorganic

  3. Simulated Historical (1901-2010) Changes in the Permafrost Extent and Active Layer Thickness in the Northern Hemisphere

    Science.gov (United States)

    Guo, Donglin; Wang, Huijun

    2017-11-01

    A growing body of simulation research has considered the dynamics of permafrost, which has an important role in the climate system of a warming world. Previous studies have concentrated on the future degradation of permafrost based on global climate models (GCMs) or data from GCMs. An accurate estimation of historical changes in permafrost is required to understand the relations between changes in permafrost and the Earth's climate and to validate the results from GCMs. Using the Community Land Model 4.5 driven by the Climate Research Unit -National Centers for Environmental Prediction (CRUNCEP) atmospheric data set and observations of changes in soil temperature and active layer thickness and present-day areal extent of permafrost, this study investigated the changes in permafrost in the Northern Hemisphere from 1901 to 2010. The results showed that the model can reproduce the interannual variations in the observed soil temperature and active layer thickness. The simulated area of present-day permafrost fits well with observations, with a bias of 2.02 × 106 km2. The area of permafrost decreased by 0.06 (0.62) × 106 km2 decade-1 from 1901 to 2009 (1979 to 2009). A clear decrease in the area of permafrost was found in response to increases in air temperatures during the period from about the 1930s to the 1940s, indicating that permafrost is sensitive to even a temporary increase in temperature. From a regional perspective, high-elevation permafrost decreases at a faster rate than high-latitude permafrost; permafrost in China shows the fastest rate of decrease, followed by Alaska, Russia, and Canada. Discrepancies in the rate of decrease in the extent of permafrost among different regions were mostly linked to the sensitivity of permafrost in the regions to increases in air temperatures rather than to the amplitude of the increase in air temperatures. An increase in the active layer thickness of 0.009 (0.071) m decade-1 was shown during the period of 1901

  4. Cell surface hydrophobicity: a key component in the degradation of polyethylene succinate by Pseudomonas sp. AKS2.

    Science.gov (United States)

    Tribedi, P; Sil, A K

    2014-02-01

    Polyethylene succinate (PES) contains hydrolysable ester bonds that make it a potential substitute for polyethylene (PE) and polypropylene (PP). Towards bioremediation of PES, we have already reported that a new strain of Pseudomonas, Pseudomonas sp. AKS2, can efficiently degrade PES and hypothesized that cell surface hydrophobicity plays an important role in this degradation process. In this study, our efforts were targeted towards establishing a correlation between cell surface hydrophobicity and PES degradation. We have manipulated cell surface hydrophobicity of AKS2 by varying concentrations of glucose and ammonium sulphate in the growth medium and subsequently examined the extent of PES degradation. We observed an increase in PES degradation by AKS2 with an increase in cell surface hydrophobicity. The increased surface hydrophobicity caused an enhanced biofilm formation on PES surface that resulted in better polymer degradation. The current study establishes a direct correlation between cell surface hydrophobicity of an organism and its potential to degrade a nonpolar polymer like PES. Cell surface hydrophobicity manipulation can be used as an important strategy to increase bioremediation of nonpolar polymer like PES. © 2013 The Society for Applied Microbiology.

  5. Simulation of permafrost changes due to technogenic influences of different ingeneering constructions used in nothern oil and gas fields

    Science.gov (United States)

    Filimonov, M. Yu; Vaganova, N. A.

    2016-10-01

    Significant amount of oil and gas is producted in Russian Federation on the territories with permafrost soils. Ice-saturated rocks thawing due to global warming or effects of various human activity will be accompanied by termocarst and others dangerous geological processes in permafrost. Design and construction of well pads in permafrost zones have some special features. The main objective is to minimize the influence of different heat sources (engineering objects) inserted into permafrost and accounting long-term forecast of development of permafrost degradation due to different factors in particular generated by human activity. In this work on the basis a mathematical model and numerical algorithms approved on 11 northern oil and gas fields some effects obtained by carrying out numerical simulations for various engineering systems are discussed.

  6. Lipase degradation of plasticized polyvinyl chloride endotracheal tube surfaces to create nanoscale features.

    Science.gov (United States)

    Machado, Mary C; Webster, Thomas J

    2017-01-01

    Polyvinyl chloride (PVC) endotracheal tubes (ETTs) nanoetched with a fungal lipase have been shown to reduce bacterial growth and biofilm formation and could be an inexpensive solution to the complex problem of ventilator-associated pneumonia (VAP). Although bacterial growth and colonization on these nanoetched materials have been well characterized, little is known about the mechanism by which the fungal lipase degrades the PVC and, thus, alters its properties to minimize bacteria functions. This study used X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to better describe the surface chemistry of both unetched and lipase nanoetched PVC ETT. ATR-FTIR analysis of the unetched and treated surfaces showed a similar presence of a plasticizer. This was confirmed by XPS analysis, which showed an increase of carbon and the presence of oxygen on both unetched and nanoetched surfaces. A quantitative comparison of the FTIR spectra revealed significant correlations (Pearson's correlation, R =0.997 [ R 2 =0.994, P degradation of the plasticizer by the fungal lipase. In contrast, results from this study did demonstrate significantly increased nanoscale surface features on the lipase etched compared to non-etched PVC ETTs. This led to a change in surface energetics, which altered ion adsorption to the ETTs. Thus, these results showed that PVC surfaces nanoetched with a 0.1% lipase solution for 48 hours have no significant change on surface chemistry but do significantly increase nanoscale surface roughness and alters ion adsorption, which suggests that the unique properties of these materials, including their previously reported ability to decrease bacterial adhesion and growth, are due to the changes in the degree of the nanoscale roughness, not changes in their surface chemistry.

  7. On Degradation of Cast Iron Surface-Protective Paint Coat Joint

    Directory of Open Access Journals (Sweden)

    Tupaj M.

    2016-09-01

    Full Text Available The paper is a presentation of a study on issues concerning degradation of protective paint coat having an adverse impact on aesthetic qualities of thin-walled cast-iron castings fabricated in furan resin sand. Microscopic examination and microanalyses of chemistry indicated that under the coat of paint covering the surface of a thin-walled casting, layers of oxides could be found presence of which can be most probably attributed to careless cleaning of the casting surface before the paint application process, as well as corrosion pits evidencing existence of damp residues under the paint layers contributing to creation of corrosion micro-cells

  8. Modeling of Transmittance Degradation Caused by Optical Surface Contamination by Atomic Oxygen Reaction with Adsorbed Silicones

    Science.gov (United States)

    Snyder, Aaron; Banks, Bruce; Miller, Sharon; Stueber, Thomas; Sechkar, Edward

    2001-01-01

    A numerical procedure is presented to calculate transmittance degradation caused by contaminant films on spacecraft surfaces produced through the interaction of orbital atomic oxygen (AO) with volatile silicones and hydrocarbons from spacecraft components. In the model, contaminant accretion is dependent on the adsorption of species, depletion reactions due to gas-surface collisions, desorption, and surface reactions between AO and silicone producing SiO(x), (where x is near 2). A detailed description of the procedure used to calculate the constituents of the contaminant layer is presented, including the equations that govern the evolution of fractional coverage by specie type. As an illustrative example of film growth, calculation results using a prototype code that calculates the evolution of surface coverage by specie type is presented and discussed. An example of the transmittance degradation caused by surface interaction of AO with deposited contaminant is presented for the case of exponentially decaying contaminant flux. These examples are performed using hypothetical values for the process parameters.

  9. New insights in permafrost modelling

    Science.gov (United States)

    Tubini, Niccolò; Serafin, Francesco; Gruber, Stephan; Casulli, Vincenzo; Rigon, Riccardo

    2017-04-01

    Simulating freezing soil has ignored for long time in mainstream surface hydrology. However, it has indubitably a large influence on soil infiltrability and an even larger influence on the soil energy budget, and, over large spatial scales, a considerable feedback on climate. The topic is difficult because it involves concepts of disequilibrium Thermodynamics and also because, once solved the theoretical problem, integration of the resulting partial differential equations in a robust manner, is not trivial at all. In this abstract, we are presenting a new algorithm to estimate the water and energy budget in freezing soils. The first step is a derivation of a new equation for freezing soil mass budget (called generalized Richards equation) based on the freezing equals drying hypothesis (Miller 1965). The second step is the re-derivation of the energy budget. Finally there is the application of new techniques based on the double nested Newton algorithm (Casulli and Zanolli, 2010) to integrate the coupled equations. Some examples of the freezing dynamics and comparison with the Dall'Amico et al. (2011) algorithm are also shown. References Casulli, V., & Zanolli,P. (2010). A nested newton-type algorithm for finite colume methods solving Richards' equation in mixed form. SIAM J. SCI. Comput., 32(4), 2225-2273. Dall'Amico, M., Endrizzi, S., Gruber, S., & Rigon, R. (2011). A robust and energy-conserving model of freezing variably-saturated soil. The Cryosphere, 5(2), 469-484. http://doi.org/10.5194/tc-5-469-2011 Miller, R.: Phase equilibria and soil freezing, in: Permafrost: Proceedings of the Second International Conference. Washington DC: National Academy of Science-National Research Council, 287, 193-197, 1965.

  10. A permafrost distribution estimate for the Southern Alps, New Zealand, inferred from topoclimatic conditions at rock glacier sites

    Science.gov (United States)

    Sattler, Katrin; Mackintosh, Andrew; Anderson, Brian; Norton, Kevin; de Róiste, Mairead

    2014-05-01

    The presence of numerous rock glaciers and perennial snow patches indicate the existence of discontinuous alpine permafrost in New Zealand's Southern Alps. However, research on the geographic extent of permafrost in the South Island has been limited. Existing estimates are restricted to single mountain ranges or focus on steep bedrock permafrost. A recent global-scale estimate has not been evaluated by local observations. We present the results of a regional, spatially distributed permafrost estimate for the Southern Alps, focusing on debris-covered slopes. Permafrost distribution modelling was based on the statistical evaluation of 280 active and relict rock glaciers. Logistic regression identified characteristic topoclimatic conditions at the head area of presently active rock glaciers. Statistical relationships between permafrost presence, mean annual air temperature, and potential incoming solar radiation in snow-free months were subsequently used to calculate the spatially distributed probability of permafrost occurrence. The potential permafrost extent was delineated using a probability threshold of ≥ 0.6. Model results suggest that topoclimatic conditions are favourable for permafrost occurrence above ~ 2000 m a.s.l. in the central Southern Alps and above ~ 2150 m a.s.l. in the northern ranges. This gradient in permafrost altitude reflects the warmer climate at lower latitudes. Model results were locally validated by BTS (bottom temperature of snow cover) data derived from two-year continuous ground surface temperature (GST) measurements in the Ben Ohau Range, central Southern Alps. Applicability of BTS measurements for permafrost mapping had not been tested previously in the maritime setting of New Zealand, where common warm spells during winter can result in isothermal snow pack conditions, preventing the inference of late-winter equilibrium temperatures. BTS-indicated permafrost sites were in good agreement with modelled permafrost probabilities at the

  11. The effect of surface modification by nitrogen plasma on photocatalytic degradation of polyvinyl chloride films

    Science.gov (United States)

    Xiao-jing, L.; Guan-jun, Q.; Jie-rong, C.

    2008-08-01

    The solid-phase photocatalytic degradation of poly(vinyl chloride) (PVC) films was investigated under the ambient air in order to assess the feasibility of developing photodegradable polymers. Nitrogen plasma was used to modify PVC films to enhance the photocatalytic degradation of PVC with nano-sized anatase TiO 2. The plasma parameter varied in this study is discharge power from 30 to 120 W for a constant treatment time of 60 s and a constant gas pressure of 10 Pa. The photodegradation of the plasma-treated PVC-TiO 2 films was compared with that of pure PVC films and PVC-TiO 2 films performing weight loss monitoring, scanning electron microscopy (SEM) analysis, contact angle measurements, electron spin resonance (ESR), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The wettability of the plasma-treated PVC is improved significantly. ESR revealed that the signal of radicals on the surface of the plasma-treated PVC film was enhanced after the treatment. Furthermore, the weight loss indicated that TiO 2 speeds up the photocatalytic degradation of PVC chains. The SEM image of the plasma-treated PVC-TiO 2 film showed a lot of crack on the film surface after irradiation. XPS indicated that the C and Cl atomic concentration reached minimum values on the surface of plasma-treated PVC-TiO 2 under identical photocatalytic condition. The experimental results reveal that plasma treatment can obviously enhance the photocatalytic degradation of PVC.

  12. Structure elucidation and degradation kinetic study of Ofloxacin using surface enhanced Raman spectroscopy

    Science.gov (United States)

    El-Zahry, Marwa R.; Lendl, Bernhard

    2018-03-01

    A simple, fast and sensitive surface enhanced Raman spectroscopy (SERS) method for quantitative determination of fluoroquinolone antibiotic Ofloxacin (OFX) is presented. Also the stability behavior of OFX was investigated by monitoring the SERS spectra of OFX after various degradation processes. Acidic, basic and oxidative force degradation processes were applied at different time intervals. The forced degradation conditions were conducted and followed using SERS method utilizing silver nanoparticles (Ag NPs) as a SERS substrate. The Ag NPs colloids were prepared by reduction of silver nitrate using polyethyelene glycol (PEG) as a reducing and stabilizing agent. Validation tests were done in accordance with International Conference on Harmonization (ICH) guidelines. The calibration curve with a correlation coefficient (R = 0.9992) was constructed as a relationship between the concentration range of OFX (100-500 ng/ml) and SERS intensity at 1394 cm- 1 band. LOD and LOQ values were calculated and found to be 23.5 ng/ml and 72.6 ng/ml, respectively. The developed method was applied successfully for quantitation of OFX in different pharmaceutical dosage forms. Kinetic parameters were calculated including rate constant of the degradation of the studied antibiotic.

  13. Surface-Atmosphere Moisture Coupling in Eurasian Frozen Ground Regions

    Science.gov (United States)

    Frauenfeld, O. W.; Ford, T.

    2014-12-01

    Permafrost represents an impermeable barrier to moisture, resulting in a saturated or near-saturated surface layer during the warm season in many continuous and discontinuous permafrost zones. These surface conditions could lead to enhanced convection and precipitation during the warm season, and significant local recycling of moisture. In areas underlain by sporadic or isolated permafrost, or in seasonally frozen areas, the moisture can drain away more readily, resulting in much drier soil conditions. As climate change causes frozen ground degradation, this will thus also alter the patterns of atmospheric convection, moisture recycling, and the hydrologic cycle in high-latitude land areas. In this study, we analyze evaporative fraction (EF) as a proxy for evapotranspiration, and precipitation from the Modern-Era Retrospective analysis for Research and Applications (MERRA-land) reanalysis dataset. We focus on 1979-2012 and document patterns and changes in EF over the Eurasian high latitudes. We find strong, positive April EF trends over the study period, particularly in the Lena River Basin, 80% of which is underlain by continuous permafrost. In fact, these significant positive trends in spring EF are strongest over continuous permafrost across the Eurasian high latitudes, but negative for sporadic and isolated permafrost. In addition, we find a strong, statistically significant relationship between EF anomalies and the probability of subsequent precipitation over the Lena Basin during April. This association therefore suggests a potential land-atmosphere coupling between frozen ground and precipitation. As the permafrost and seasonally frozen ground distribution changes in the future, this will likely have repercussions for the Arctic hydrologic cycle.

  14. Quantifying Permafrost Characteristics with DCR-ERT

    Science.gov (United States)

    Schnabel, W.; Trochim, E.; Munk, J.; Kanevskiy, M. Z.; Shur, Y.; Fortier, R.

    2012-12-01

    Geophysical methods are an efficient method for quantifying permafrost characteristics for Arctic road design and engineering. In the Alaskan Arctic construction and maintenance of roads requires integration of permafrost; ground that is below 0 degrees C for two or more years. Features such as ice content and temperature are critical for understanding current and future ground conditions for planning, design and evaluation of engineering applications. This study focused on the proposed Foothills West Transportation Access project corridor where the purpose is to construct a new all-season road connecting the Dalton Highway to Umiat. Four major areas were chosen that represented a range of conditions including gravel bars, alluvial plains, tussock tundra (both unburned and burned conditions), high and low centered ice-wedge polygons and an active thermokarst feature. Direct-current resistivity using galvanic contact (DCR-ERT) was applied over transects. In conjunction complimentary site data including boreholes, active layer depths, vegetation descriptions and site photographs was obtained. The boreholes provided information on soil morphology, ice texture and gravimetric moisture content. Horizontal and vertical resolutions in the DCR-ERT were varied to determine the presence or absence of ground ice; subsurface heterogeneity; and the depth to groundwater (if present). The four main DCR-ERT methods used were: 84 electrodes with 2 m spacing; 42 electrodes with 0.5 m spacing; 42 electrodes with 2 m spacing; and 84 electrodes with 1 m spacing. In terms of identifying the ground ice characteristics the higher horizontal resolution DCR-ERT transects with either 42 or 84 electrodes and 0.5 or 1 m spacing were best able to differentiate wedge-ice. This evaluation is based on a combination of both borehole stratigraphy and surface characteristics. Simulated apparent resistivity values for permafrost areas varied from a low of 4582 Ω m to a high of 10034 Ω m. Previous

  15. Optimization of integrated chemical-biological degradation of a reactive azo dye using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Sudarjanto, Gatut [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia); Keller-Lehmann, Beatrice [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia); Keller, Jurg [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia)]. E-mail: j.keller@awmc.uq.edu.au

    2006-11-02

    The integrated chemical-biological degradation combining advanced oxidation by UV/H{sub 2}O{sub 2} followed by aerobic biodegradation was used to degrade C.I. Reactive Azo Red 195A, commonly used in the textile industry in Australia. An experimental design based on the response surface method was applied to evaluate the interactive effects of influencing factors (UV irradiation time, initial hydrogen peroxide dosage and recirculation ratio of the system) on decolourisation efficiency and optimizing the operating conditions of the treatment process. The effects were determined by the measurement of dye concentration and soluble chemical oxygen demand (S-COD). The results showed that the dye and S-COD removal were affected by all factors individually and interactively. Maximal colour degradation performance was predicted, and experimentally validated, with no recirculation, 30 min UV irradiation and 500 mg H{sub 2}O{sub 2}/L. The model predictions for colour removal, based on a three-factor/five-level Box-Wilson central composite design and the response surface method analysis, were found to be very close to additional experimental results obtained under near optimal conditions. This demonstrates the benefits of this approach in achieving good predictions while minimising the number of experiments required.

  16. Optimization of integrated chemical-biological degradation of a reactive azo dye using response surface methodology

    International Nuclear Information System (INIS)

    Sudarjanto, Gatut; Keller-Lehmann, Beatrice; Keller, Jurg

    2006-01-01

    The integrated chemical-biological degradation combining advanced oxidation by UV/H 2 O 2 followed by aerobic biodegradation was used to degrade C.I. Reactive Azo Red 195A, commonly used in the textile industry in Australia. An experimental design based on the response surface method was applied to evaluate the interactive effects of influencing factors (UV irradiation time, initial hydrogen peroxide dosage and recirculation ratio of the system) on decolourisation efficiency and optimizing the operating conditions of the treatment process. The effects were determined by the measurement of dye concentration and soluble chemical oxygen demand (S-COD). The results showed that the dye and S-COD removal were affected by all factors individually and interactively. Maximal colour degradation performance was predicted, and experimentally validated, with no recirculation, 30 min UV irradiation and 500 mg H 2 O 2 /L. The model predictions for colour removal, based on a three-factor/five-level Box-Wilson central composite design and the response surface method analysis, were found to be very close to additional experimental results obtained under near optimal conditions. This demonstrates the benefits of this approach in achieving good predictions while minimising the number of experiments required

  17. Cooperation in carbon source degradation shapes spatial self-organization of microbial consortia on hydrated surfaces.

    Science.gov (United States)

    Tecon, Robin; Or, Dani

    2017-03-06

    Mounting evidence suggests that natural microbial communities exhibit a high level of spatial organization at the micrometric scale that facilitate ecological interactions and support biogeochemical cycles. Microbial patterns are difficult to study definitively in natural environments due to complex biodiversity, observability and variable physicochemical factors. Here, we examine how trophic dependencies give rise to self-organized spatial patterns of a well-defined bacterial consortium grown on hydrated surfaces. The model consortium consisted of two Pseudomonas putida mutant strains that can fully degrade the aromatic hydrocarbon toluene. We demonstrated that obligate cooperation in toluene degradation (cooperative mutualism) favored convergence of 1:1 partner ratio and strong intermixing at the microscale (10-100 μm). In contrast, competition for benzoate, a compound degraded independently by both strains, led to distinct segregation patterns. Emergence of a persistent spatial pattern has been predicted for surface attached microbial activity in liquid films that mediate diffusive exchanges while permitting limited cell movement (colony expansion). This study of a simple microbial consortium offers mechanistic glimpses into the rules governing the assembly and functioning of complex sessile communities, and points to general principles of spatial organization with potential applications for natural and engineered microbial systems.

  18. Effects of permafrost thaw on carbon emissions under aerobic and anaerobic environments in the Great Hing'an Mountains, China.

    Science.gov (United States)

    Song, Changchun; Wang, Xianwei; Miao, Yuqing; Wang, Jiaoyue; Mao, Rong; Song, Yanyu

    2014-07-15

    The carbon (C) pool of permafrost peatland is very important for the global C cycle. Little is known about how permafrost thaw could influence C emissions in the Great Hing'an Mountains of China. Through aerobic and anaerobic incubation experiments, we studied the effects of permafrost thaw on CH4 and CO2 emissions. The rates of CH4 and CO2 emissions were measured at -10, 0 and 10°C. Although there were still C emissions below 0°C, rates of CH4 and CO2 emissions significantly increased with permafrost thaw under aerobic and anaerobic conditions. The C release under aerobic conditions was greater than under anaerobic conditions, suggesting that permafrost thaw and resulting soil environment change should be important influences on C emissions. However, CH4 stored in permafrost soils could affect accurate estimation of CH4 emissions from microbial degradation. Calculated Q10 values in the permafrost soils were significantly higher than values in active-layer soils under aerobic conditions. Our results highlight that permafrost soils have greater potential decomposability than soils of the active layer, and such carbon decomposition would be more responsive to the aerobic environment. © 2013 Elsevier B.V. All rights reserved.

  19. Risk assessment associated to possible concrete degradation of a near surface disposal facility

    Science.gov (United States)

    Capra, B.; Billard, Y.; Wacquier, W.; Gens, R.

    2013-07-01

    This article outlines a risk analysis of possible concrete degradation performed in the framework of the preparation of the Safety Report of ONDRAF/NIRAS, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials, for the construction and operation of a near surface disposal facility of category A waste - short-lived low and intermediate level waste - in Dessel. The main degradation mechanism considered is the carbonation of different concrete components over different periods (from the building phase up to 2000 years), which induces corrosion of the rebars. A dedicated methodology mixing risk analysis and numerical modeling of concrete carbonation has been developed to assess the critical risks of the disposal facility at different periods. According to the results obtained, risk mapping was used to assess the impact of carbonation of concrete on the different components at the different stages. The most important risk is related to an extreme situation with complete removal of the earth cover and side embankment.

  20. Marine oil degrading bacteria related to oil inputs and surface currents in the western Caribbean Sea

    International Nuclear Information System (INIS)

    Lizarraga-Partida, M.L.; Vicuna, F.B.I.; Chang, I.W.

    1990-01-01

    The distribution of oil degrading bacteria (ODB) and its ratios to viable heterotrophic bacteria (CFU) and direct counts (AODC) were examined in relation to the surface currents of the western Caribbean Sea. High ODB/CFU and ODB/AODC ratios were found, suggesting that chronic sources of hydrocarbons in the region may have a larger impact than those in the southern Gulf of Mexico, where previous studies have been performed. It was concluded that, in western Caribbean waters, the distribution of oil degrading bacteria, or its ratios to CFU or AODC, could be useful indicators of chronic oil inputs originating at the east of the Caribbean Sea, as well as their motions afterwards. (author)

  1. Microorganisms Trapped Within Permafrost Ice In The Fox Permafrost Tunnel, Alaska

    Science.gov (United States)

    Katayama, T.; Tanaka, M.; Douglas, T. A.; Cai, Y.; Tomita, F.; Asano, K.; Fukuda, M.

    2008-12-01

    Several different types of massive ice are common in permafrost. Ice wedges are easily recognized by their shape and foliated structure. They grow syngenetically or epigenetically as a result of repeated cycles of frost cracking followed by the infiltration of snow, melt water, soil or other material into the open frost cracks. Material incorporated into ice wedges becomes frozen and preserved. Pool ice, another massive ice type, is formed by the freezing of water resting on top of frozen thermokarst sediment or melting wedges and is not foliated. The Fox Permafrost Tunnel in Fairbanks was excavated within the discontinuous permafrost zone of central Alaska and it contains permafrost, ice wedges, and pool ice preserved at roughly -3°C. We collected samples from five ice wedges and three pool ice structures in the Fox Permafrost Tunnel. If the microorganisms were incorporated into the ice during its formation, a community analysis of the microorganisms could elucidate the environment in which the ice was formed. Organic material from sediments in the tunnel was radiocarbon-dated between 14,000 and 30,000 years BP. However, it is still not clear when the ice wedges were formed or subsequently deformed because they are only partially exposed and their upper surfaces are above the tunnel walls. The objectives of our study were to determine the biogeochemical conditions during massive ice formation and to analyze the microbial community within the ices by incubation-based and DNA-based analyses. The geochemical profile and the PCR-DGGE band patterns of bacteria among five ice wedge and 3 portions of pool ice samples were markedly different. The DGGE band patterns of fungi were simple with a few bands of fungi or yeast. The dominant bands of ice wedge and pool ice samples were affiliated with the genus Geomyces and Doratomyces, respectively. Phylogenetic analysis using rRNA gene ITS regions indicated isolates of Geomyces spp. from different ice wedges were affiliated

  2. Does mountain permafrost in Mongolia control water availability?

    Science.gov (United States)

    Menzel, Lucas; Kopp, Benjamin; Munkhjargal, Munkhdavaa

    2016-04-01

    In semi-arid Mongolia, continuous and discontinuous permafrost covers wide parts of the mountains, especially in the northwest of the country. Long-term analysis of annual discharge from rivers draining the mountainous parts shows high temporal variability, with some evidence of decreasing trends, accompanied by decreased intra-annual variability. Investigations show that annual precipitation features small changes while annual air temperature significantly increased over the last decades, with warming rates clearly outranging the global average. Widespread and drastic changes in land cover through forest fires in northern Mongolia might have an additional impact on water retention and the stability of permafrost. Hence, there is concern about an increased degradation of mountain permafrost and a possible impact on river discharge and water availability. Decreased water availability from the mountains would have strong socio-economic implications for the population living in the steppe belt downstream the mountains. Therefore, a monitoring program has been conducted in northern Mongolia that aims to improve the understanding of how climate change and forest fires are influencing mountain permafrost and water resources. The study region, Sugnugur valley, is located about 100 km north of Ulaanbaatar and includes the transition belt between the steppe, the boreal zone and the alpine tundra of the Khentii Mountains. Extensive measurements of soil temperatures, soil moisture, discharge and climatic parameters have been carried out along transects which stretch across the Sugnugur river valley and include steppe, boreal forest as well as burnt forest. First results indicate that the environmental conditions show drastic changes after forest fire, with reduced water retention in the headwaters. After forest fires, changing runoff processes above the permafrost table have been observed, where water drains rapidly along preferential flow paths. This eventually leads to

  3. Permafrost: occurrence and physiochemical processes

    International Nuclear Information System (INIS)

    Ahonen, L.

    2001-10-01

    Bedrock of the Northern Hemisphere areas to the north of about the 60th latitude are nowadays dominated by permafrost conditions. Fennoscandia is a major exception being characterised by temperate climate. In studying deep geological disposal of long-living nuclear waste, long-term climatic changes have to be taken into account. One of the scenarios to be studied is the extension of the deep permafrost conditions to the disposal site. Quaternary climatic fluctuations and their possible reasons are discussed shortly. The author's conclusion is that future climatic changes cannot be undoubtedly derived from the past variations, mainly because of the current anthropogenic involvement and of the poorly known dynamics of the major climate-affecting factors like ocean currents, which cannot be treated in a deterministic way. In low-porosity crystalline rocks permafrost may propagate to the depth of about 500 metres in some thousands to ten thousands of years. On the other hand, the major effects of permafrost are related to the freezing of water in the pores. Water expands about 9 percent in freezing, and the increasing stress may lead to pressure melting of ice. Dissolved salts in water do not accommodate into the solid ice, but they form saline water or brine segregations having freezing point of even less than minus ten degrees. A front of saline water may develop beneath the frozen bedrock. Pockets of saline water may also occur in ice, and unfrozen adsorption water may occur on the grain boundaries. With respect to the radionuclide transport processes, permafrost as such is a barrier, while the unfrozen domains (taliks) beneath major lake and river systems are potential flow paths. (orig.)

  4. High Voltage Surface Degradation on Carbon Blacks in Lithium Ion Batteries

    DEFF Research Database (Denmark)

    Younesi, Reza

    In order to increase the power density of Li-ion batteries, much research is focused on developing cathode materials that can operate at high voltages above 4.5 V with a high capacity, high cycling stability, and rate capability. However, at high voltages all the components of positive electrodes...... including carbon black (CB) additives have a potential risk of degradation. Though the weight percentage of CB in commercial batteries is generally very small, the volumetric amount and thus the surface area of CB compose a rather large part of a cathode due to its small particle size (≈ 50 nm) and high...... surface area. In this work, the performance of Super P in Li-ion cells at high voltages up to 4.9 V is studied using electrochemical measurements as well as surface characterizations....

  5. Map the Permafrost and its Affected Soils and Vegetation on the Tibetan Plateau

    Science.gov (United States)

    Zhao, L.; Sheng, Y.; Pang, Q.; Zou, D.; Wang, Z.; Li, W.; Wu, X.; Yue, G.; Fang, H.; Zhao, Y.

    2015-12-01

    Great amount of literatures had been published to deal with the actual distribution and changes of permafrost on the Tibetan Plateau (TP) on the basis of observed ground temperature dataset along Qinghai-Xizang Highway and/or Railway (QXH/R) during the last several decades. But there is very limited data available in the eastern part of the QXH/R and almost no observation in the western part of QXH/R not only for the observed permafrost data, but also for the dataset on ground surface conditions, such as soil and vegetation, which are used as model parameters, initial variables, or benchmark data sets for calibration, validation, and comparison in various Earth System Models (ESMs). To evaluate the status of permafrost and its environmental conditions, such as the distribution and thermal state of permafrost, soil and vegetation on the TP, detailed investigation on permafrost were conducted in 5 regions with different climatic and geologic conditions over the whole plateau from 2009 to 2013, and more than 100 ground temperatures (GTs) monitoring boreholes were drilled and equipped with thermistors, of which 10 sites were equipped with automatic meteorological stations. Geophysical prospecting methods, such as ground penetrating radar (GPR) and electromagnetic prospecting, were used in the same time to detect the permafrost distribution and thicknesses. The monitoring data revealed that the thermal state of permafrost was well correlated with elevation, and regulated by annual precipitation, local geological, geomorphological and hydrological conditions through heat exchanges between ground and atmosphere. Different models, including GTs statistical model, Common Land Surface Model (CoLM), Noah land surface model and TTOP models, were used to map the permafrost in 5 selected regions and the whole TP, while the investigated and monitored data were used as calibration and validation for all models. Finally, we compiled the permafrost map of the TP, soil and vegetation

  6. Data analysis and mapping of the mountain permafrost distribution

    Science.gov (United States)

    Deluigi, Nicola; Lambiel, Christophe; Kanevski, Mikhail

    2017-04-01

    In Alpine environments mountain permafrost is defined as a thermal state of the ground and corresponds to any lithosphere material that is at or below 0°C for, at least, two years. Its degradation is potentially leading to an increasing rock fall activity, rock glacier accelerations and an increase in the sediment transfer rates. During the last 15 years, knowledge on this phenomenon has significantly increased thanks to many studies and monitoring projects. They revealed a spatial distribution extremely heterogeneous and complex. As a consequence, modelling the potential extent of the mountain permafrost recently became a very important task. Although existing statistical models generally offer a good overview at a regional scale, they are not always able to reproduce its strong spatial discontinuity at the micro scale. To overcome this lack, the objective of this study is to propose an alternative modelling approach using three classification algorithms belonging to statistics and machine learning: Logistic regression (LR), Support Vector Machines (SVM) and Random forests (RF). The former is a linear parametric classifier that commonly used as a benchmark classification algorithm to be employed before using more complex classifiers. Non-linear SVM is a non-parametric learning algorithm and it is a member of the so-called kernel methods. RF are an ensemble learning method based on bootstrap aggregating and offer an embedded measure of the variable importance. Permafrost evidences were selected in a 588 km2 area of the Western Swiss Alps and serve as training examples. They were mapped from field data (thermal and geoelectrical data) and ortho-image interpretation (rock glacier inventorying). The dataset was completed with environmental predictors such as altitude, mean annual air temperature, aspect, slope, potential incoming solar radiation, normalized difference vegetation index and planar, profile and combined terrain curvature indices. Aiming at predicting

  7. Geophysical mapping of palsa peatland permafrost

    Science.gov (United States)

    Sjöberg, Y.; Marklund, P.; Pettersson, R.; Lyon, S. W.

    2015-03-01

    Permafrost peatlands are hydrological and biogeochemical hotspots in the discontinuous permafrost zone. Non-intrusive geophysical methods offer a possibility to map current permafrost spatial distributions in these environments. In this study, we estimate the depths to the permafrost table and base across a peatland in northern Sweden, using ground penetrating radar and electrical resistivity tomography. Seasonal thaw frost tables (at ~0.5 m depth), taliks (2.1-6.7 m deep), and the permafrost base (at ~16 m depth) could be detected. Higher occurrences of taliks were discovered at locations with a lower relative height of permafrost landforms, which is indicative of lower ground ice content at these locations. These results highlight the added value of combining geophysical techniques for assessing spatial distributions of permafrost within the rapidly changing sporadic permafrost zone. For example, based on a back-of-the-envelope calculation for the site considered here, we estimated that the permafrost could thaw completely within the next 3 centuries. Thus there is a clear need to benchmark current permafrost distributions and characteristics, particularly in under studied regions of the pan-Arctic.

  8. Lipase degradation of plasticized polyvinyl chloride endotracheal tube surfaces to create nanoscale features

    Directory of Open Access Journals (Sweden)

    Machado MC

    2017-03-01

    Full Text Available Mary C Machado,1 Thomas J Webster2 1Center for Biomedical Engineering, Division of Engineering Brown University, Providence, RI, 2Department of Chemical Engineering, Northeastern University, Boston, MA, USA Abstract: Polyvinyl chloride (PVC endotracheal tubes (ETTs nanoetched with a fungal lipase have been shown to reduce bacterial growth and biofilm formation and could be an inexpensive solution to the complex problem of ventilator-associated pneumonia (VAP. Although bacterial growth and colonization on these nanoetched materials have been well characterized, little is known about the mechanism by which the fungal lipase degrades the PVC and, thus, alters its properties to minimize bacteria functions. This study used X-ray photoelectron spectroscopy (XPS and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR to better describe the surface chemistry of both unetched and lipase nanoetched PVC ETT. ATR-FTIR analysis of the unetched and treated surfaces showed a similar presence of a plasticizer. This was confirmed by XPS analysis, which showed an increase of carbon and the presence of oxygen on both unetched and nanoetched surfaces. A quantitative comparison of the FTIR spectra revealed significant correlations (Pearson’s correlation, R=0.997 [R2=0.994, P<0.001] between the unetched and nanomodified PVC ETT spectra, demonstrating similar surface chemistry. This analysis showed no shifting or widening of the bands in the spectra and no significant changes in the intensity of the infrared peaks due to the degradation of the plasticizer by the fungal lipase. In contrast, results from this study did demonstrate significantly increased nanoscale surface features on the lipase etched compared to non-etched PVC ETTs. This led to a change in surface energetics, which altered ion adsorption to the ETTs. Thus, these results showed that PVC surfaces nanoetched with a 0.1% lipase solution for 48 hours have no significant change

  9. Effects of Kaolin Surface Treatments on the Thermomechanical Properties and on the Degradation of Polypropylene

    OpenAIRE

    Guessoum, Melia; Nekkaa, Sorya; Fenouillot-Rimlinger, Françoise; Haddaoui, Nacerddine

    2012-01-01

    The effects of kaolin content and treatments on the thermal and mechanical properties and on the degradation of polypropylene were examined using mechanical tests, differential scanning calorimetry (DSC), and thermogravimetry (TGA). The weak interactions filler/matrix have been reinforced using a modification with urea then with an ammonium salt and a surface treatment with a silane coupling agent. The XRD results showed that the peak at the d-value of 10.7 Å increases in urea/kaolin complex,...

  10. Surface Corrosion and Microstructure Degradation of Calcium Sulfoaluminate Cement Subjected to Wet-Dry Cycles in Sulfate Solution

    Directory of Open Access Journals (Sweden)

    Wuman Zhang

    2017-01-01

    Full Text Available The hydration products of calcium sulfoaluminate (CSA cement are different from those of Portland cement. The degradation of CSA cement subjected to wet-dry cycles in sulfate solution was studied in this paper. The surface corrosion was recorded and the microstructures were examined by scanning electron microscopy (SEM. The results show that SO42-, Na+, Mg2+, and Cl− have an effect on the stability of ettringite. In the initial period of sulfate attack, salt crystallization is the main factor leading to the degradation of CSA cement specimens. The decomposition and the carbonation of ettringite will cause long-term degradation of CSA cement specimens under wet-dry cycles in sulfate solution. The surface spalling and microstructure degradation increase significantly with the increase of wet-dry cycles, sulfate concentration, and water to cement ratio. Magnesium sulfate and sodium chloride reduce the degradation when the concentration of sulfate ions is a constant value.

  11. Molecular investigations into a globally important carbon pool: Permafrost-protected carbon in Alaskan soils

    Science.gov (United States)

    Waldrop, M.P.; Wickland, K.P.; White, Rickie; Berhe, A.A.; Harden, J.W.; Romanovsky, V.E.

    2010-01-01

    The fate of carbon (C) contained within permafrost in boreal forest environments is an important consideration for the current and future carbon cycle as soils warm in northern latitudes. Currently, little is known about the microbiology or chemistry of permafrost soils that may affect its decomposition once soils thaw. We tested the hypothesis that low microbial abundances and activities in permafrost soils limit decomposition rates compared with active layer soils. We examined active layer and permafrost soils near Fairbanks, AK, the Yukon River, and the Arctic Circle. Soils were incubated in the lab under aerobic and anaerobic conditions. Gas fluxes at -5 and 5 ??C were measured to calculate temperature response quotients (Q10). The Q10 was lower in permafrost soils (average 2.7) compared with active layer soils (average 7.5). Soil nutrients, leachable dissolved organic C (DOC) quality and quantity, and nuclear magnetic resonance spectroscopy of the soils revealed that the organic matter within permafrost soils is as labile, or even more so, than surface soils. Microbial abundances (fungi, bacteria, and subgroups: methanogens and Basidiomycetes) and exoenzyme activities involved in decomposition were lower in permafrost soils compared with active layer soils, which, together with the chemical data, supports the reduced Q10 values. CH4 fluxes were correlated with methanogen abundance and the highest CH4 production came from active layer soils. These results suggest that permafrost soils have high inherent decomposability, but low microbial abundances and activities reduce the temperature sensitivity of C fluxes. Despite these inherent limitations, however, respiration per unit soil C was higher in permafrost soils compared with active layer soils, suggesting that decomposition and heterotrophic respiration may contribute to a positive feedback to warming of this eco region. Published 2010. This article is a US Government work and is in the public domain in the

  12. Evolution and environmental degradation of superhydrophobic aspen and black locust leaf surfaces

    Science.gov (United States)

    Tranquada, George Christopher

    The current study is focused on the characterization of four natural leaf species (quaking, bigtooth and columnar european aspen as well as black locust) possessing a unique dual-scale cuticle structure composed of micro- and nano-scale asperities, which are able to effectively resist wetting (superhydrophobic), characteristic of The Lotus Effect. Scanning Electron Microscopy (SEM) was used to track the growth and evolution of their distinctive nano-scale epicuticular wax (ECW) morphologies over one full growing season. In addition, the stability of their superhydrophobic property was tested in various environments. It was determined that the long-term stability of these surfaces is tentatively linked to various environmental stress factors. Specifically, a combination of high temperature and humidity caused the degradation of nanoscale asperities and loss of the superhydrophobic property. The dual-scale surface structure was found to provide a suitable template for the design of future superhydrophobic engineering materials.

  13. Effects of PV Module Soiling on Glass Surface Resistance and Potential-Induced Degradation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter; Burton, Patrick; Hendrickson, Alex; Spartaru, Sergiu; Glick, Stephen; Terwilliger, Kent

    2015-12-03

    The sheet resistance of three soil types (Arizona road dust, soot, and sea salt) on glass were measured by the transmission line method as a function of relative humidity (RH) between 39% and 95% at 60 degrees C. Sea salt yielded a 3.5 order of magnitude decrease in resistance on the glass surface when the RH was increased over this RH range. Arizona road dust showed reduced sheet resistance at lower RH, but with less humidity sensitivity over the range tested. The soot sample did not show significant resistivity change compared to the unsoiled control. Photovoltaic modules with sea salt on their faces were step-stressed between 25% and 95% RH at 60 degrees C applying -1000 V bias to the active cell circuit. Leakage current from the cell circuit to ground ranged between two and ten times higher than that of the unsoiled controls. Degradation rate of modules with salt on the surface increased with increasing RH and time.

  14. Microscopic degradation mechanism of polyimide film caused by surface discharge under bipolar continuous square impulse voltage

    Science.gov (United States)

    Luo, Yang; Wu, Guang-Ning; Liu, Ji-Wu; Peng, Jia; Gao, Guo-Qiang; Zhu, Guang-Ya; Wang, Peng; Cao, Kai-Jiang

    2014-02-01

    Polyimide (PI) film is an important type of insulating material used in inverter-fed motors. Partial discharge (PD) under a sequence of high-frequency square impulses is one of the key factors that lead to premature failures in insulation systems of inverter-fed motors. In order to explore the damage mechanism of PI film caused by discharge, an aging system of surface discharge under bipolar continuous square impulse voltage (BCSIV) is designed based on the ASTM 2275 01 standard and the electrical aging tests of PI film samples are performed above the partial discharge inception voltage (PDIV). The chemical bonds of PI polymer chains are analyzed through Fourier transform infrared spectroscopy (FTIR) and the dielectric properties of unaged and aged PI samples are investigated by LCR testers HIOKI 3532-50. Finally, the micro-morphology and micro-structure changes of PI film samples are observed through scanning electron microscopy (SEM). The results show that the physical and chemical effects of discharge cut off the chemical bonds of PI polymer chains. The fractures of ether bond (C—O—C) and imide ring (C—N—C) on the backbone of a PI polymer chain leads to the decrease of molecular weight, which results in the degradation of PI polymers and the generation of new chemical groups and materials, like carboxylic acid, ketone, aldehydes, etc. The variation of microscopic structure of PI polymers can change the orientation ability of polarizable units when the samples are under an AC electric field, which would cause the dielectric constant ɛ to increase and dielectric loss tan δ to decrease. The SEM images show that the degradation path of PI film is initiated from the surface and then gradually extends to the interior with continuous aging. The injection charge could result in the PI macromolecular chain degradation and increase the trap density in the PI polymer bulk.

  15. The structure optimization of gas-phase surface discharge and its application for dye degradation

    Science.gov (United States)

    Ying, CAO; Jie, LI; Nan, JIANG; Yan, WU; Kefeng, SHANG; Na, LU

    2018-05-01

    A gas-phase surface discharge (GSD) was employed to optimize the discharge reactor structure and investigate the dye degradation. A dye mixture of methylene blue, acid orange and methyl orange was used as a model pollutant. The results indicated that the reactor structure of the GSD system with the ratio of tube inner surface area and volume of 2.48, screw pitch between a high-voltage electrode of 9.7 mm, high-voltage electrode wire diameter of 0.8 mm, dielectric tube thickness of 2.0 mm and tube inner diameter of 16.13 mm presented a better ozone (O3) generation efficiency. Furthermore, a larger screw pitch and smaller wire diameter enhanced the O3 generation. After the dye mixture degradation by the optimized GSD system, 73.21% and 50.74% of the chemical oxygen demand (COD) and total organic carbon removal rate were achieved within 20 min, respectively, and the biochemical oxygen demand (BOD) and biodegradability (BOD/COD) improved.

  16. Thermal stability analysis under embankment with asphalt pavement and cement pavement in permafrost regions.

    Science.gov (United States)

    Junwei, Zhang; Jinping, Li; Xiaojuan, Quan

    2013-01-01

    The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The maximum depth of temperature field under the embankment for concrete pavements and asphalt pavements was also studied by using the finite element method. The results of numerical analysis indicate that there were remarkable seasonal differences of the ground temperatures in superficial layer between asphalt pavement and concrete pavement. The maximum influencing depth of temperature field under the permafrost embankment for every pavement was under the depth of 8 m. The thawed cores under both embankments have close relation with the maximum thawed depth, the embankment height, and the service time. The effective measurements will be proposed to keep the thermal stabilities of highway embankment by the results.

  17. Thermal Stability Analysis under Embankment with Asphalt Pavement and Cement Pavement in Permafrost Regions

    Directory of Open Access Journals (Sweden)

    Zhang Junwei

    2013-01-01

    Full Text Available The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The maximum depth of temperature field under the embankment for concrete pavements and asphalt pavements was also studied by using the finite element method. The results of numerical analysis indicate that there were remarkable seasonal differences of the ground temperatures in superficial layer between asphalt pavement and concrete pavement. The maximum influencing depth of temperature field under the permafrost embankment for every pavement was under the depth of 8 m. The thawed cores under both embankments have close relation with the maximum thawed depth, the embankment height, and the service time. The effective measurements will be proposed to keep the thermal stabilities of highway embankment by the results.

  18. Hydrogeology, chemical and microbial activity measurement through deep permafrost.

    Science.gov (United States)

    Stotler, Randy L; Frape, Shaun K; Freifeld, Barry M; Holden, Brian; Onstott, Tullis C; Ruskeeniemi, Timo; Chan, Eric

    2011-01-01

    Little is known about hydrogeochemical conditions beneath thick permafrost, particularly in fractured crystalline rock, due to difficulty in accessing this environment. The purpose of this investigation was to develop methods to obtain physical, chemical, and microbial information about the subpermafrost environment from a surface-drilled borehole. Using a U-tube, gas and water samples were collected, along with temperature, pressure, and hydraulic conductivity measurements, 420 m below ground surface, within a 535 m long, angled borehole at High Lake, Nunavut, Canada, in an area with 460-m-thick permafrost. Piezometric head was well above the base of the permafrost, near land surface. Initial water samples were contaminated with drill fluid, with later samples <40% drill fluid. The salinity of the non-drill fluid component was <20,000 mg/L, had a Ca/Na ratio above 1, with δ(18) O values ∼5‰ lower than the local surface water. The fluid isotopic composition was affected by the permafrost-formation process. Nonbacteriogenic CH(4) was present and the sample location was within methane hydrate stability field. Sampling lines froze before uncontaminated samples from the subpermafrost environment could be obtained, yet the available time to obtain water samples was extended compared to previous studies. Temperature measurements collected from a distributed temperature sensor indicated that this issue can be overcome easily in the future. The lack of methanogenic CH(4) is consistent with the high sulfate concentrations observed in cores. The combined surface-drilled borehole/U-tube approach can provide a large amount of physical, chemical, and microbial data from the subpermafrost environment with few, controllable, sources of contamination. Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association.

  19. Hydrogeology, chemical and microbial activity measurement through deep permafrost

    Energy Technology Data Exchange (ETDEWEB)

    Stotler, R.L.; Frape, S.K.; Freifeld, B.M.; Holden, B.; Onstott, T.C.; Ruskeeniemi, T.; Chan, E.

    2010-04-01

    Little is known about hydrogeochemical conditions beneath thick permafrost, particularly in fractured crystalline rock, due to difficulty in accessing this environment. The purpose of this investigation was to develop methods to obtain physical, chemical, and microbial information about the subpermafrost environment from a surface-drilled borehole. Using a U-tube, gas and water samples were collected, along with temperature, pressure, and hydraulic conductivity measurements, 420 m below ground surface, within a 535 m long, angled borehole at High Lake, Nunavut, Canada, in an area with 460-m-thick permafrost. Piezometric head was well above the base of the permafrost, near land surface. Initial water samples were contaminated with drill fluid, with later samples <40% drill fluid. The salinity of the non-drill fluid component was <20,000 mg/L, had a Ca/Na ratio above 1, with {delta}{sup 18}O values {approx}5{per_thousand} lower than the local surface water. The fluid isotopic composition was affected by the permafrost-formation process. Nonbacteriogenic CH{sub 4} was present and the sample location was within methane hydrate stability field. Sampling lines froze before uncontaminated samples from the subpermafrost environment could be obtained, yet the available time to obtain water samples was extended compared to previous studies. Temperature measurements collected from a distributed temperature sensor indicated that this issue can be overcome easily in the future. The lack of methanogenic CH{sub 4} is consistent with the high sulfate concentrations observed in cores. The combined surface-drilled borehole/U-tube approach can provide a large amount of physical, chemical, and microbial data from the subpermafrost environment with few, controllable, sources of contamination.

  20. Regional permafrost distribution based on remote sensing data

    Science.gov (United States)

    Prantl, Hannah; Sailer, Rudolf; Stötter, Johann; Nagler, Thomas

    2017-04-01

    The detection of permafrost phenomena and its distribution in mountain environments as well as the monitoring of changes of permafrost with respect to climatic changes is important for alpine risk, infrastructure, natural hazards and climate change studies. It is assumed that in Iceland less than ten percent of the land surface is underlain by permafrost and that most of it may disappear under global warming in the 21st century. In particular regions these changes will cause sincere problems for the society in mountainous regions. But because of the complexity of permafrost detection, the knowledge about its distribution in Iceland is currently not very well evaluated and only based on small-scale observations. As permafrost is at most not directly observable, different indicators, e.g. rock glaciers and perennial snow patches, can be mapped to identify the distribution of permafrost. The study site is situated on the Tröllaskagi peninsula, in Northern Iceland. The peninsula is situated between Skagafjörður and Eyjafjörður and the highest summits reach an altitude of about 1400. For large-scale identification of perennial snow patches (PSP) over the Tröllaskagi peninsula remote sensing techniques are a practicable technique. In our study, we use optical satellite (Landsat-5/7/8 and Sentinel-2B) data in combination with aerial images to map and monitor the spatial distribution of perennial snow patches, indicating a low or negative ground temperature underneath. After an atmospheric correction of the satellite data, pan sharpening of the Landsat data and resampling the Sentinel-2B data, and Normalized Difference Snow Index (NDSI) calculations, the perennial snow patches are classified in i) mainly permafrost, ii) mainly wind and iii) mainly avalanche induced origin. For that purpose, topographic information such as slope angle, aspect and curvature are determined from a DEM of Tröllaskagi peninsula. In a first step a digital elevation model with a grid size

  1. Permafrost carbon-climate feedbacks accelerate global warming.

    Science.gov (United States)

    Koven, Charles D; Ringeval, Bruno; Friedlingstein, Pierre; Ciais, Philippe; Cadule, Patricia; Khvorostyanov, Dmitry; Krinner, Gerhard; Tarnocai, Charles

    2011-09-06

    Permafrost soils contain enormous amounts of organic carbon, which could act as a positive feedback to global climate change due to enhanced respiration rates with warming. We have used a terrestrial ecosystem model that includes permafrost carbon dynamics, inhibition of respiration in frozen soil layers, vertical mixing of soil carbon from surface to permafrost layers, and CH(4) emissions from flooded areas, and which better matches new circumpolar inventories of soil carbon stocks, to explore the potential for carbon-climate feedbacks at high latitudes. Contrary to model results for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), when permafrost processes are included, terrestrial ecosystems north of 60°N could shift from being a sink to a source of CO(2) by the end of the 21st century when forced by a Special Report on Emissions Scenarios (SRES) A2 climate change scenario. Between 1860 and 2100, the model response to combined CO(2) fertilization and climate change changes from a sink of 68 Pg to a 27 + -7 Pg sink to 4 + -18 Pg source, depending on the processes and parameter values used. The integrated change in carbon due to climate change shifts from near zero, which is within the range of previous model estimates, to a climate-induced loss of carbon by ecosystems in the range of 25 + -3 to 85 + -16 Pg C, depending on processes included in the model, with a best estimate of a 62 + -7 Pg C loss. Methane emissions from high-latitude regions are calculated to increase from 34 Tg CH(4)/y to 41-70 Tg CH(4)/y, with increases due to CO(2) fertilization, permafrost thaw, and warming-induced increased CH(4) flux densities partially offset by a reduction in wetland extent.

  2. Active Microwave Satellite Data for High Latitude Pan-Boreal/ Arctic Permafrost Monitoring

    Science.gov (United States)

    Bartsch, A.; Naeimi, V.; Park, S.-E.; Sabel, D.

    2009-11-01

    Circumpolar permafrost monitoring is currently largely based on in-situ measurements and modelling. The capabilities of satellite data with respect to operational monitoring need to be assessed. Within the ESA DUE Permafrost project a wide range of EO datasets will be explored and integrated in an information system with extensive involvement of the permafrost research community. This comprises pan-boreal/arctic to local scale products. This paper discusses the potential of active microwave satellite products (scatterometer and SAR) for permafrost modeling and monitoring on pan-boreal/arctic scale. This includes soil moisture and freeze/thaw. Water in the soil impacts the ground thermal regime. The currently available Metop ASCAT (C-band) data also allow the identification of long term surface wetness anomalies based on ERS as well as the detection of frozen ground status. The possibilities of MetOp ASCAT and ENVISAT ASAR Global Monitoring Mode for the latter application are explored in this paper.

  3. Transfer of glyphosate and its degradate AMPA to surface waters through urban sewerage systems.

    Science.gov (United States)

    Botta, Fabrizio; Lavison, Gwenaëlle; Couturier, Guillaume; Alliot, Fabrice; Moreau-Guigon, Elodie; Fauchon, Nils; Guery, Bénédicte; Chevreuil, Marc; Blanchoud, Hélène

    2009-09-01

    A study of glyphosate and aminomethyl phosphonic acid (AMPA) transfer in the Orge watershed (France) was carried out during 2007 and 2008. Water samples were collected in surface water, wastewater sewer, storm sewer and wastewater treatment plant (WWTP). These two molecules appeared to be the most frequently detected ones in the rivers and usually exceeded the European quality standard concentrations of 0.1microg L(-1) for drinking water. The annual glyphosate estimated load was 1.9 kg year(-1) upstream (agricultural zone) and 179.5 kg year(-1) at the catchment outlet (urban zone). This result suggests that the contamination of this basin by glyphosate is essentially from urban origin (road and railway applications). Glyphosate reached surface water prevalently through storm sewer during rainfall event. Maximum concentrations were detected in storm sewer just after a rainfall event (75-90 microg L(-1)). High concentrations of glyphosate in surface water during rainfall events reflected urban runoff impact. AMPA was always detected in the sewerage system. This molecule reached surface water mainly via WWTP effluent and also through storm sewer. Variations in concentrations of AMPA during hydrological episodes were minor compared to glyphosate variations. Our study highlights that AMPA and glyphosate origins in urban area are different. During dry period, detergent degradation seemed to be the major AMPA source in wastewater.

  4. Hydrological patterns in warming permafrost: comparing results from a control and drained site on a floodplain tundra near Chersky, Northeast Siberia

    Science.gov (United States)

    Boelck, Sandra; Goeckede, Mathias; Hildebrandt, Anke; Vonk, Jorien; Heimann, Martin

    2017-04-01

    Permafrost areas represent a major reservoir for organic carbon. At the same time, permafrost ecosystems are very susceptible to changing climate conditions. The stability of this reservoir, i.e. changes in lateral and vertical carbon fluxes in permafrost ecosystems, largely depends on groundwater level, temperature and vegetation community. Particularly during summer when the soil thaws and a so-called active layer develops, fluctuations in carbon flux rates are often dominantly driven by water availability. Such dry soil conditions are expected to become more frequent in the future due to deepening active layers as a consequence of climate change. This could result in degradation of polygonal tundra landscape properties with channelled water transport pathways. Therefore, water table depth and the associated groundwater fluxes are crucial to understand transport patterns and to quantify the lateral export of carbon through an aquatic system. Consequently, a fundamental understanding of hydrological patterns on ecosystem structure and function is required to close the carbon balance of permafrost ecosystems. This study focuses on small-scale hydrological patterns and its influencing factors, such as topography and precipitation events. Near Chersky, Northeast Siberia, we monitored (i) a control site of floodplain tundra, and (ii) a drained site, characterised by a drainage ring which was constructed in 2004, to study the effects of water availability on the carbon cycle. This experimental disturbance simulates drainage effects following the degradation of ice-rich permafrost ecosystems under future climate change. Continuous monitoring of water table depth in drained and control areas revealed small-scale water table variations. At several key locations, we collected water samples to determine the isotopic composition (δ18O, δD) of surface water, suprapermafrost groundwater and precipitation. Furthermore, a weir at the drainage ditch was constructed to directly

  5. Monitoring cell culture media degradation using surface enhanced Raman scattering (SERS) spectroscopy.

    Science.gov (United States)

    Calvet, Amandine; Ryder, Alan G

    2014-08-20

    The quality of the cell culture media used in biopharmaceutical manufacturing is a crucial factor affecting bioprocess performance and the quality of the final product. Due to their complex composition these media are inherently unstable, and significant compositional variations can occur particularly when in the prepared liquid state. For example photo-degradation of cell culture media can have adverse effects on cell viability and thus process performance. There is therefore, from quality control, quality assurance and process management view points, an urgent demand for the development of rapid and inexpensive tools for the stability monitoring of these complex mixtures. Spectroscopic methods, based on fluorescence or Raman measurements, have now become viable alternatives to more time-consuming and expensive (on a unit analysis cost) chromatographic and/or mass spectrometry based methods for routine analysis of media. Here we demonstrate the application of surface enhanced Raman scattering (SERS) spectroscopy for the simple, fast, analysis of cell culture media degradation. Once stringent reproducibility controls are implemented, chemometric data analysis methods can then be used to rapidly monitor the compositional changes in chemically defined media. SERS shows clearly that even when media are stored at low temperature (2-8°C) and in the dark, significant chemical changes occur, particularly with regard to cysteine/cystine concentration. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Risk assessment associated to possible concrete degradation of a near surface disposal facility

    Directory of Open Access Journals (Sweden)

    Wacquier W.

    2013-07-01

    Full Text Available This article outlines a risk analysis of possible concrete degradation performed in the framework of the preparation of the Safety Report of ONDRAF/NIRAS, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials, for the construction and operation of a near surface disposal facility of category A waste – short-lived low and intermediate level waste – in Dessel. The main degradation mechanism considered is the carbonation of different concrete components over different periods (from the building phase up to 2000 years, which induces corrosion of the rebars. A dedicated methodology mixing risk analysis and numerical modeling of concrete carbonation has been developed to assess the critical risks of the disposal facility at different periods. According to the results obtained, risk mapping was used to assess the impact of carbonation of concrete on the different components at the different stages. The most important risk is related to an extreme situation with complete removal of the earth cover and side embankment.

  7. Surface binding sites (SBSs), mechanism and regulation of enzymes degrading amylopectin and α-limit dextrins

    DEFF Research Database (Denmark)

    Møller, Marie Sofie; Cockburn, Darrell; Nielsen, Jonas W.

    2013-01-01

    Certain enzymes interact with polysaccharides at surface binding sites (SBSs) situated outside of their active sites. SBSs are not easily identified and their function has been discerned in relatively few cases. Starch degradation is a concerted action involving GH13 hydrolases. New insight...... into barley seed α-amylase 1 (AMY1) and limit dextrinase (LD) includes i. kinetics of bi-exponential amylopectin hydrolysis by AMY1, one reaction having low Km (8 μg/mL) and high kcat (57 s-1) and the other high Km (97 μg/mL) and low kcat (23 s-1). β-Cyclodextrin (β-CD) inhibits the first reaction by binding...

  8. MALDI imaging of enzymatic degradation of glycerides by lipase on textile surface

    DEFF Research Database (Denmark)

    Hall-Andersen, Jonatan; Kaasgaard, Svend G; Janfelt, Christian

    2018-01-01

    Most modern laundry detergents contain enzymes such as proteases, amylases, and lipases for more efficient removal of stains containing proteins, carbohydrates, and lipids during wash at low temperature. The function of the lipases is to hydrolyse the hydrophobic triglycerides from fats and oils...... to the more hydrophilic lipids diglycerides, monoglycerides and free fatty acids. Here, we use MALDI imaging to study the effect of enzymatic degradation of triglycerides by lipases directly on the textile surface. Textile samples were created by using swatches of different textile blends, adding a lipid...... stain and simulating washing cycles using well-defined detergents with lipase concentrations ranging between 0 and 0.5ppm. After washing, the textile swatches as well as cryo-sections of the swatches were imaged using MALDI imaging in positive ion mode at pixel sizes of 15-75μm. Similar samples were...

  9. Effects of Kaolin Surface Treatments on the Thermomechanical Properties and on the Degradation of Polypropylene

    Directory of Open Access Journals (Sweden)

    Melia Guessoum

    2012-01-01

    Full Text Available The effects of kaolin content and treatments on the thermal and mechanical properties and on the degradation of polypropylene were examined using mechanical tests, differential scanning calorimetry (DSC, and thermogravimetry (TGA. The weak interactions filler/matrix have been reinforced using a modification with urea then with an ammonium salt and a surface treatment with a silane coupling agent. The XRD results showed that the peak at the d-value of 10.7 Å increases in urea/kaolin complex, but the treatment with the ammonium salt caused the return to the initial state of the clay. FTIR results showed the appearance of new bands characteristic of the interactions between urea and kaolinite and the alkylammonium and kaolinite. The mechanical properties of the composites exhibited important variations while the DSC results showed the decrease of the crystallization temperature as a function of kaolin content. TGA thermograms pointed out the improvement of the composites' thermal stability.

  10. Fresh and composted industrial sludge restore soil functions in surface soil of degraded agricultural land.

    Science.gov (United States)

    Arif, Muhammad Saleem; Riaz, Muhammad; Shahzad, Sher Muhammad; Yasmeen, Tahira; Ashraf, Muhammad; Siddique, Muhammad; Mubarik, Muhammad Salman; Bragazza, Luca; Buttler, Alexandre

    2018-04-01

    A field study was conducted to test the potential of 5-year consecutive application of fresh industrial sludge (FIS) and composted industrial sludge (CIS) to restore soil functions at surface (0-15cm) and subsurface (15-30cm) of the degraded agricultural land. Sludge amendments increased soil fertility parameters including total organic carbon (TOC), soil available nitrogen (SAN), soil available phosphorus (SAP) and soil available potassium (SAK) at 0-15cm depth. Soil enzyme activities i.e. dehydrogenase (DHA), β-glucosidase (BGA) and alkaline phosphatase (ALp) were significantly enhanced by FIS and CIS amendments in surface soil. However, urease activity (UA) and acid phosphatase (ACp) were significantly reduced compared to control soil. The results showed that sludge amendments significantly increased microbial biomass nitrogen (MBN) and microbial biomass phosphorus (MBP) at both soil depth, and soil microbial biomass carbon (MBC) only at 0-15cm depth. Significant changes were also observed in the population of soil culturable microflora (bacteria, fungi and actinomycetes) with CIS amendment in surface soil suggesting persistence of microbial activity owing to the addition of organic matter source. Sludge amendments significantly reduced soil heavy metal concentrations at 0-15cm depth, and the effect was more pronounced with CIS compared to unamended control soil. Sludge amendments generally had no significant impact on soil heavy metal concentrations in subsoil. Agronomic viability test involving maize was performed to evaluate phytotoxicity of soil solution extract at surface and sub-surface soil. Maize seeds grown in solution extract (0-15cm) from sludge treated soil showed a significant increase of relative seed germination (RSG), relative root growth (RRG) and germination index (GI). These results suggested that both sludge amendments significantly improved soil properties, however, the CIS amendment was relatively more effective in restoring soil functions

  11. Proximity effect among cellulose-degrading enzymes displayed on the Saccharomyces cerevisiae cell surface.

    Science.gov (United States)

    Bae, Jungu; Kuroda, Kouichi; Ueda, Mitsuyoshi

    2015-01-01

    Proximity effect is a form of synergistic effect exhibited when cellulases work within a short distance from each other, and this effect can be a key factor in enhancing saccharification efficiency. In this study, we evaluated the proximity effect between 3 cellulose-degrading enzymes displayed on the Saccharomyces cerevisiae cell surface, that is, endoglucanase, cellobiohydrolase, and β-glucosidase. We constructed 2 kinds of arming yeasts through genome integration: ALL-yeast, which simultaneously displayed the 3 cellulases (thus, the different cellulases were near each other), and MIX-yeast, a mixture of 3 kinds of single-cellulase-displaying yeasts (the cellulases were far apart). The cellulases were tagged with a fluorescence protein or polypeptide to visualize and quantify their display. To evaluate the proximity effect, we compared the activities of ALL-yeast and MIX-yeast with respect to degrading phosphoric acid-swollen cellulose after adjusting for the cellulase amounts. ALL-yeast exhibited 1.25-fold or 2.22-fold higher activity than MIX-yeast did at a yeast concentration equal to the yeast cell number in 1 ml of yeast suspension with an optical density (OD) at 600 nm of 10 (OD10) or OD0.1. At OD0.1, the distance between the 3 cellulases was greater than that at OD10 in MIX-yeast, but the distance remained the same in ALL-yeast; thus, the difference between the cellulose-degrading activities of ALL-yeast and MIX-yeast increased (to 2.22-fold) at OD0.1, which strongly supports the proximity effect between the displayed cellulases. A proximity effect was also observed for crystalline cellulose (Avicel). We expect the proximity effect to further increase when enzyme display efficiency is enhanced, which would further increase cellulose-degrading activity. This arming yeast technology can also be applied to examine proximity effects in other diverse fields. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  12. Utilizing Vegetation Indices as a Proxy to Characterize the Stability of a Railway Embankment in a Permafrost Region

    Directory of Open Access Journals (Sweden)

    Priscilla Addison

    2016-11-01

    Full Text Available Degrading permafrost conditions around the world are posing stability issues for infrastructure constructed on them. Railway lines have exceptionally low tolerances for differential settlements associated with permafrost degradation due to the potential for train derailments. Railway owners with tracks in permafrost regions therefore make it a priority to identify potential settlement locations so that proper maintenance or embankment stabilization measures can be applied to ensure smooth and safe operations. The extensive discontinuous permafrost zone along the Hudson Bay Railway (HBR in Northern Manitoba, Canada, has been experiencing accelerated deterioration, resulting in differential settlements that necessitate continuous annual maintenance to avoid slow orders and operational interruptions. This paper seeks to characterize the different permafrost degradation susceptibilities present at the study site. Track geometry exceptions were compared against remotely sensed vegetation indices to establish a relationship between track quality and vegetation density. This relationship was used as a proxy for subsurface condition verified by electrical resistivity tomography. The established relationship was then used to develop a three-level degradation susceptibility chart to indicate low, moderate and high susceptibility regions. The defined susceptibility regions can be used to better allocate the limited maintenance resources and also help inform potentially long-term stabilization measures for the severely affected sections.

  13. Photocatalytic degradation of metoprolol tartrate in suspensions of two TiO{sub 2}-based photocatalysts with different surface area. Identification of intermediates and proposal of degradation pathways

    Energy Technology Data Exchange (ETDEWEB)

    Abramovic, Biljana, E-mail: biljana.abramovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Kler, Sanja, E-mail: sanja.kler@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Sojic, Daniela, E-mail: daniela.sojic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Lausevic, Mila, E-mail: milal@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Radovic, Tanja, E-mail: tradovic@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Vione, Davide, E-mail: davide.vione@unito.it [Dipartimento di Chimica Analitica, Universita di Torino, Via Pietro Giuria 5, 10125 Torino (Italy)

    2011-12-30

    Highlights: Black-Right-Pointing-Pointer Kinetics and efficiency of photocatalytic degradation of the {beta}{sub 1}-blocker metoprolol tartrate (MET). Black-Right-Pointing-Pointer Two TiO{sub 2} specimens employed. Black-Right-Pointing-Pointer Faster degradation of MET, but slower mineralization, obtained with the TiO{sub 2} specimen having lower surface area. Black-Right-Pointing-Pointer Photocatalytic transformation pathways of MET including mineralization. - Abstract: This study investigates the efficiency of the photocatalytic degradation of metoprolol tartrate (MET), a widely used {beta}{sub 1}-blocker, in TiO{sub 2} suspensions of Wackherr's 'Oxyde de titane standard' and Degussa P25. The study encompasses transformation kinetics and efficiency, identification of intermediates and reaction pathways. In the investigated range of initial concentrations (0.01-0.1 mM), the photocatalytic degradation of MET in the first stage of the reaction followed approximately a pseudo-first order kinetics. The TiO{sub 2} Wackherr induced a significantly faster MET degradation compared to TiO{sub 2} Degussa P25 when relatively high substrate concentrations were used. By examining the effect of ethanol as a scavenger of hydroxyl radicals ({center_dot}OH), it was shown that the reaction with {center_dot}OH played the main role in the photocatalytic degradation of MET. After 240 min of irradiation the reaction intermediates were almost completely mineralized to CO{sub 2} and H{sub 2}O, while the nitrogen was predominantly present as NH{sub 4}{sup +}. Reaction intermediates were studied in detail and a number of them were identified using LC-MS/MS (ESI+), which allowed the proposal of a tentative pathway for the photocatalytic transformation of MET as a function of the TiO{sub 2} specimen.

  14. The Aiguille du Midi (Mont Blanc massif): a unique high-Alpine site to study bedrock permafrost

    Science.gov (United States)

    Deline, P.; Coviello, V.; Cremonese, E.; Gruber, S.; Krautblatter, M.; Malet, S. Jaillet (1), E.; Morra di Cella, U.; Noetzli, J.; Pogliotti, P.; Verleysdonk, S.

    2009-04-01

    Permafrost and its change in steep high-Alpine rock walls remain insufficiently understood because of the difficulties of in situ measurements. A large proportion of permafrost studies is mainly based on modelling, with a few existing instrumented sites and a resulting lack of process understanding. Yet, a number of rockfalls that occurred in the last decade in the Alps are likely related to climatically-driven permafrost degradation, as indicated by ice in starting zones, increased air temperature, and modelling studies. Starting off in the framework of the French-Italian PERMAdataROC project and presently under development within the EU co-funded project PermaNET (Permafrost long-term monitoring network: www.permanet-alpinespace.eu), our investigations at the Aiguille du Midi begin in 2005. The summit (3842 m a.s.l) is accessible from Chamonix by a cable car which was built at the end of the 1950s. Half a million tourists visit the site each year. Because of its elevation, geometry, and year-round accessibility to rock slopes of diverse aspects and to galleries, the site was chosen for: - Monitoring of the thermal regime in steep rock walls. Thermistors were installed at depths of 2, 10, 30 and 55 cm, at all aspects and with slope angles in the range 60-90° (determining e.g. the presence and influence of snow). - Measurements of high altitude climatic data (air temperature and humidity, incoming and outgoing solar radiation, wind speed and direction) perpendicular to the rockwall surface, by movable automatic weather stations. Together with the rock temperature measurements, these data (see Morra et al., poster in session CR4.1) can be used for physically-based model validation (see Pogliotti et al., oral presentation in session CR4.1) or statistical models construction of rock temperature distribution and variability in the rock walls. - Making a 3D-high-resolution DEM by long-range (rock walls) and short-range (galleries) terrestrial laser scanning

  15. Biomarker and carbon isotope constraints (δ13C, Δ14C) on sources and cycling of particulate organic matter discharged by large Siberian rivers draining permafrost areas

    International Nuclear Information System (INIS)

    Winterfeld, Maria

    2014-08-01

    consistent with inputs of OM from non-woody angiosperm sources mixed with organic matter derived from woody gymnosperm sources. A simple linear mixing model based on the lignin phenol distributions indicates organic matter in TSM samples from the delta and Buor Khaya Bay surface sediments contain comparable contributions from gymnosperm sources, which are primarily from the taiga forests south of the delta, and angiosperm material typical for tundra vegetation. Considering the small area covered by tundra (∝12% of total catchment), the input of tundra-derived OM input is substantial and likely to increase in a warming Arctic. Radiocarbon compositions (Δ 14 C) of bulk OM in Lena River TSM samples varied from -55 to -391 permille, translating into 14 C ages of 395 to 3920 years BP. Using δ 13 C compositions to estimate the fraction of phytoplankton-derived OM and assuming that this material has a modern 14 C signature, we inferred the Δ 14 C compositions of terrigenous OM in TSM exported by the Lena River to range between -190 and -700 permille. Such variability in the ages of terrigenous OM (i.e. 1640 to 9720 14 C years BP) reflects the heterogeneous composition and residence time of OM in the Lena River catchment soils (Holocene to Pleistocene ages). Lignin phenol and Δ 14 C compositions of surface sediments from the adjacent Buor Khaya Bay suggest that terrestrial OM deposited there is older and more degraded than materials present in river particles and catchment soils. Stronger diagenetic alteration in Lena Delta TSM and marine sediments relative to soils may reflect degradation of more labile components during permafrost thawing and transport. Despite the high natural heterogeneity in catchment soils, the lignin biomarker compositions and radiocarbon ages of terrestrial OM exported by the Lena River reflect catchment characteristics such as vegetation and soil type. Climate warming related changes in the Lena River catchment may be detectable in changing lignin

  16. Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw

    Science.gov (United States)

    Vonk, J. E.; Mann, P. J.; Dowdy, K. L.; Davydova, A.; Davydov, S. P.; Zimov, N.; Spencer, R. G. M.; Bulygina, E. B.; Eglinton, T. I.; Holmes, R. M.

    2013-09-01

    Pleistocene Yedoma permafrost contains nearly a third of all organic matter (OM) stored in circum-arctic permafrost and is characterized by the presence of massive ice wedges. Due to its rapid formation by sediment accumulation and subsequent frozen storage, Yedoma OM is relatively well preserved and highly biologically available (biolabile) upon thaw. A better understanding of the processes regulating Yedoma degradation is important to improve estimates of the response and magnitude of permafrost carbon feedbacks to climate warming. In this study, we examine the composition of ice wedges and the influence of ice wedge thaw on the biolability of Yedoma OM. Incubation assays were used to assess OM biolability, fluorescence spectroscopy to characterize the OM composition, and potential enzyme activity rates to examine the controls and regulation of OM degradation. We show that increasing amounts of ice wedge melt water in Yedoma-leached incubations enhanced the loss of dissolved OM over time. This may be attributed to the presence of low-molecular weight compounds and low initial phenolic content in the OM of ice wedges, providing a readily available substrate that promotes the degradation of Yedoma OC. The physical vulnerability of ice wedges upon thaw (causing irreversible collapse), combined with the composition of ice wedge-engrained OM (co-metabolizing old OM), underlines the particularly strong potential of Yedoma to generate a positive feedback to climate warming relative to other forms of non-ice wedge permafrost.

  17. Interaction of thermal and mechanical processes in steep permafrost rock walls: A conceptual approach

    Science.gov (United States)

    Draebing, D.; Krautblatter, M.; Dikau, R.

    2014-12-01

    Degradation of permafrost rock wall decreases stability and can initiate rock slope instability of all magnitudes. Rock instability is controlled by the balance of shear forces and shear resistances. The sensitivity of slope stability to warming results from a complex interplay of shear forces and resistances. Conductive, convective and advective heat transport processes act to warm, degrade and thaw permafrost in rock walls. On a seasonal scale, snow cover changes are a poorly understood key control of the timing and extent of thawing and permafrost degradation. We identified two potential critical time windows where shear forces might exceed shear resistances of the rock. In early summer combined hydrostatic and cryostatic pressure can cause a peak in shear force exceeding high frozen shear resistance and in autumn fast increasing shear forces can exceed slower increasing shear resistance. On a multiannual system scale, shear resistances change from predominantly rock-mechanically to ice-mechanically controlled. Progressive rock bridge failure results in an increase of sensitivity to warming. Climate change alters snow cover and duration and, hereby, thermal and mechanical processes in the rock wall. Amplified thawing of permafrost will result in higher rock slope instability and rock fall activity. We present a holistic conceptual approach connecting thermal and mechanical processes, validate parts of the model with geophysical and kinematic data and develop future scenarios to enhance understanding on system scale.

  18. Simultaneous degradation of organophosphate and organochlorine pesticides by Sphingobium japonicum UT26 with surface-displayed organophosphorus hydrolase.

    Science.gov (United States)

    Cao, Xiangyu; Yang, Chao; Liu, Ruihua; Li, Qiang; Zhang, Wei; Liu, Jianli; Song, Cunjiang; Qiao, Chuanling; Mulchandani, Ashok

    2013-04-01

    A genetically engineered microorganism (GEM) capable of simultaneously degrading organophosphate and organochlorine pesticides was constructed for the first time by display of organophosphorus hydrolase (OPH) on the cell surface of a hexachlorocyclohexane (HCH)-degrading Sphingobium japonicum UT26. The GEM could potentially be used for removing the two classes of pesticides that may be present in mixtures at contaminated sites. A surface anchor system derived from the truncated ice nucleation protein (INPNC) from Pseudomonas syringae was used to target OPH onto the cell surface of UT26, reducing the potential substrate uptake limitation. The surface localization of INPNC-OPH fusion was verified by cell fractionation, western blot, proteinase accessibility, and immunofluorescence microscopy. Furthermore, the functionality of the surface-exposed OPH was demonstrated by OPH activity assays. Surface display of INPNC-OPH fusion (82 kDa) neither inhibited cell growth nor affected cell viability. The engineered UT26 could degrade parathion as well as γ-HCH rapidly in minimal salt medium. The removal of parathion and γ-HCH by engineered UT26 in sterile and non-sterile soil was also studied. In both soil samples, a mixture of parathion (100 mg kg(-1)) and γ-HCH (10 mg kg(-1)) could be degraded completely within 15 days. Soil treatment results indicated that the engineered UT26 is a promising multifunctional bacterium that could be used for the bioremediation of multiple pesticide-contaminated environments.

  19. Thermo-mechanical processing of austenitic steel to mitigate surface related degradation

    Science.gov (United States)

    Idell, Yaakov Jonathan

    Thermo-mechanical processing plays an important role in materials property optimization through microstructure modification, required by demanding modern materials applications. Due to the critical role of austenitic stainless steels, such as 316L, as structural components in harsh environments, e.g. in nuclear power plants, improved degradation resistance is desirable. A novel two-dimensional plane strain machining process has shown promise achieving significant grain size refinement through severe plastic deformation (SPD) and imparting large strains in the surface and subsurface regions of the substrate in various metals and alloys. The deformation process creates a heavily deformed 20 -- 30 micron thick nanocrystalline surface layer with increased hardness and minimal martensite formation. Post-deformation processing annealing treatments have been applied to assess stability of the refined scale microstructures and the potential for obtaining grain boundary engineered microstructures with increased fraction of low-energy grain boundaries and altered grain boundary network structure. Varying the deformation and heat treatment process parameters, allows for development of a full understanding of the nanocrystalline layer and cross-section of the surface substrate created. Micro-characterization was performed using hardness measurements, magnetometry, x-ray diffraction, scanning and transmission electron microscopy to assess property and microstructural changes. This study provides a fundamental understanding of two-dimensional plane strain machining as a thermo-mechanical processing technique, which may in the future deliver capabilities for creating grain boundary engineered surface modified components, typified by a combination of grain refinement with improved grain boundary network interconnectivity attributes suitable for use in harsh environments, such as those in commercial nuclear power plants where improved resistance to irradiation stress corrosion

  20. Distinguishing between old and modern permafrost sources in the northeast Siberian land–shelf system with compound-specific δ2H analysis

    Directory of Open Access Journals (Sweden)

    J. E. Vonk

    2017-08-01

    Full Text Available Pleistocene ice complex permafrost deposits contain roughly a quarter of the organic carbon (OC stored in permafrost (PF terrain. When permafrost thaws, its OC is remobilized into the (aquatic environment where it is available for degradation, transport or burial. Aquatic or coastal environments contain sedimentary reservoirs that can serve as archives of past climatic change. As permafrost thaw is increasing throughout the Arctic, these reservoirs are important locations to assess the fate of remobilized permafrost OC.We here present compound-specific deuterium (δ2H analysis on leaf waxes as a tool to distinguish between OC released from thawing Pleistocene permafrost (ice complex deposits; ICD and from thawing Holocene permafrost (from near-surface soils. Bulk geochemistry (%OC; δ13C; %total nitrogen, TN was analyzed as well as the concentrations and δ2H signatures of long-chain n-alkanes (C21 to C33 and mid- to long-chain n-alkanoic acids (C16 to C30 extracted from both ICD-PF samples (n =  9 and modern vegetation and O-horizon (topsoil-PF samples (n =  9 from across the northeast Siberian Arctic. Results show that these topsoil-PF samples have higher %OC, higher OC ∕ TN values and more depleted δ13C-OC values than ICD-PF samples, suggesting that these former samples trace a fresher soil and/or vegetation source. Whereas the two investigated sources differ on the bulk geochemical level, they are, however, virtually indistinguishable when using leaf wax concentrations and ratios. However, on the molecular isotope level, leaf wax biomarker δ2H values are statistically different between topsoil PF and ICD PF. For example, the mean δ2H value of C29 n-alkane was −246 ± 13 ‰ (mean ± SD for topsoil PF and −280 ± 12 ‰ for ICD PF. With a dynamic isotopic range (difference between two sources of 34 to 50 ‰; the isotopic fingerprints of individual, abundant, biomarker molecules from leaf waxes can

  1. The degradation behaviour of nine diverse contaminants in urban surface water and wastewater prior to water treatment.

    Science.gov (United States)

    Cormier, Guillaume; Barbeau, Benoit; Arp, Hans Peter H; Sauvé, Sébastien

    2015-12-01

    An increasing diversity of emerging contaminants are entering urban surface water and wastewater, posing unknown risks for the environment. One of the main contemporary challenges in ensuring water quality is to design efficient strategies for minimizing such risks. As a first step in such strategies, it is important to establish the fate and degradation behavior of contaminants prior to any engineered secondary water treatment. Such information is relevant for assessing treatment solutions by simple storage, or to assess the impacts of contaminant spreading in the absence of water treatment, such as during times of flooding or in areas of poor infrastructure. Therefore in this study we examined the degradation behavior of a broad array of water contaminants in actual urban surface water and wastewater, in the presence and absence of naturally occurring bacteria and at two temperatures. The chemicals included caffeine, sulfamethoxazole, carbamazepine, atrazine, 17β-estradiol, ethinylestradiol, diclofenac, desethylatrazine and norethindrone. Little information on the degradation behavior of these pollutants in actual influent wastewater exist, nor in general in water for desethylatrazine (a transformation product of atrazine) and the synthetic hormone norethindrone. Investigations were done in aerobic conditions, in the absence of sunlight. The results suggest that all chemicals except estradiol are stable in urban surface water, and in waste water neither abiotic nor biological degradation in the absence of sunlight contribute significantly to the disappearance of desethylatrazine, atrazine, carbamazepine and diclofenac. Biological degradation in wastewater was effective at transforming norethindrone, 17β-estradiol, ethinylestradiol, caffeine and sulfamethoxazole, with measured degradation rate constants k and half-lives ranging respectively from 0.0082-0.52 d(-1) and 1.3-85 days. The obtained degradation data generally followed a pseudo-first-order-kinetic model

  2. Studies on nitrile rubber degradation in zinc bromide completion fluid and its prevention by surface fluorination

    Science.gov (United States)

    Vega-Cantu, Yadira Itzel

    Poly(acrylonitrile-co-butadiene) or nitrile-butadiene rubber (NBR) is frequently used as an O-ring material in the oil extraction industry due to its excellent chemical properties and resistance to oil. However, degradation of NBR gaskets is known to occur during the well completion and oil extraction process where packers are exposed to completion fluids such as ZnBr2 brine. Under these conditions NBR exhibits accelerated chemical degradation resulting in embrittlement and cracking. Samples of NBR, poly(acrylonitrile) (PAN) and poly(butadiene) (PB) have been exposed to ZnBr2 based completion fluid, and analyzed by ATR and diffuse reflectance IR. Analysis shows the ZnBr2 based completion fluid promotes hydrolysis of the nitrile group to form amides and carboxylic groups. Analysis also shows that carbon-carbon double bonds in NBR are unaffected after short exposure to zinc bromide based completion fluid, but are quickly hydrolyzed in acidic bromide mixtures. Although fluoropolymers have excellent chemical resistance, their strength is less than nitrile rubber and replacing the usual gasket materials with fluoroelastomers is expensive. However, a fluoropolymer surface on a nitrile elastomer can provide the needed chemical resistance while retaining their strength. In this study, we have shown that this can be achieved by direct fluorination, a rather easy and inexpensive process. Samples of NBR O-rings have been fluorinated by exposure to F2 and F2/HF mixtures at various temperatures. Fluorination with F 2 produces the desired fluoropolymer layer; however, fluorination by F2/HF mixtures gave a smoother fluorinated layer at lower temperatures and shorter times. Fluorinated samples were exposed to ZnBr2 drilling fluid and solvents. Elemental analysis shows that the fluorinated layer eliminates ZnBr2 diffusion into the NBR polymeric matrix. It was also found that surface fluorination significantly retards the loss of mechanical properties such as elasticity, tensile

  3. Investigations into the Degradation of PTFE Surface Properties by Accelerated Aging Tests

    Directory of Open Access Journals (Sweden)

    C. Fragassa

    2016-06-01

    Full Text Available This paper describes an accelerate aging procedure used for investigating the surface alteration of PTFE gaskets commercialized by two alternative producers. These gaskets are installed in modern process plants where tires moulds are cleaned inside a multistage ultrasonic process. The surface of gaskets degrades inexplicably under ordinary operative conditions after a relatively short period. Even if these gaskets are exposed to a combination of ultrasonic waves, temperature, humidity and acid attack, the PTFE properties of resistance nominally exclude the possibility of severe erosion phenomena as highlighted during the real utilization. A possible explanation could be represented by the presence of unexpected chemical compounds emerging from the disaggregation of highly reacting elements from the tire composition. In particular, it is believed that the unpredicted combination of fluorides and chlorides could explain the violent chemical attack highlighted on steel tanks and on their gaskets. But no evidence exists. Thus, the experimental characterization of PTFE properties has to follow an appropriate accelerated aging, aiming at actuating the specific mechanics of wearing as in industrial use.

  4. Surface characterization and cathodoluminescence degradation of ZnO thin films

    Science.gov (United States)

    Hasabeldaim, E.; Ntwaeaborwa, O. M.; Kroon, R. E.; Craciun, V.; Coetsee, E.; Swart, H. C.

    2017-12-01

    ZnO thin films were successfully synthesized by the sol-gel method using the spin coater technique. The films were annealed at 600 °C in air for two hours and in Ar/H2(5%) flow for 30 and 60 min, respectively. Structural analysis, surface morphology and characterization, as well as optical analysis (photoluminescence and cathodeluminescence (CL)) were done on the samples and discussed in detail. CL degradation during prolonged electron irradiation on the films was also determined. A preferential orientation of the c-axis perpendicular to the surface was observed from X-ray diffraction data showing the peak from the (002) plane for the films annealed in both the air and in the H2 flow. The film annealed in air exhibited a broad visible emission as well as a strong ultraviolet emission. A single-green emission peak around 511 nm was obtained from the film that was annealed in Ar/H2 flow for 60 min. The CL study revealed that the intensity of the green emission (511 nm) was very stable during electron bombardment for electron doses of more than 160 C/cm2.

  5. Endothelial surface layer degradation by chronic hyaluronidase infusion induces proteinuria in apolipoprotein E-deficient mice.

    Directory of Open Access Journals (Sweden)

    Marijn C Meuwese

    Full Text Available OBJECTIVE: Functional studies show that disruption of endothelial surface layer (ESL is accompanied by enhanced sensitivity of the vasculature towards atherogenic stimuli. However, relevance of ESL disruption as causal mechanism for vascular dysfunction remains to be demonstrated. We examined if loss of ESL through enzymatic degradation would affect vascular barrier properties in an atherogenic model. METHODS: Eight week old male apolipoprotein E deficient mice on Western-type diet for 10 weeks received continuous active or heat-inactivated hyaluronidase (10 U/hr, i.v. through an osmotic minipump during 4 weeks. Blood chemistry and anatomic changes in both macrovasculature and kidneys were examined. RESULTS: Infusion with active hyaluronidase resulted in decreased ESL (0.32±0.22 mL and plasma volume (1.03±0.18 mL compared to inactivated hyaluronidase (0.52±0.29 mL and 1.28±0.08 mL, p<0.05 respectively.Active hyaluronidase increased proteinuria compared to inactive hyaluronidase (0.27±0.02 vs. 0.15±0.01 µg/µg protein/creatinin, p<0.05 without changes in glomerular morphology or development of tubulo-interstitial inflammation. Atherosclerotic lesions in the aortic branches showed increased matrix production (collagen, 32±5 vs. 18±3%; glycosaminoglycans, 11±5 vs. 0.1±0.01%, active vs. inactive hyaluronidase, p<0.05. CONCLUSION: ESL degradation in apoE deficient mice contributes to reduced increased urinary protein excretion without significant changes in renal morphology. Second, the induction of compositional changes in atherogenic plaques by hyaluronidase point towards increased plaque vulnerability. These findings support further efforts to evaluate whether ESL restoration is a valuable target to prevent (micro vascular disease progression.

  6. The Last Glacial Ecosystems of North Siberia: Permafrost-Sealed Evidence from Fossiliferous Cryolithic Formations

    Science.gov (United States)

    Chlachula, Jiri

    2017-04-01

    Multi-proxy palaeoecology and geoarchaeology records released from degrading permafrost in the Yana River Basin and the tributary valleys (66-67°N) confirm the past existence of natural conditions for sustainment of the Pleistocene megafauna as well as the last glacial peopling of this sub-polar area. Well-preserved and taxonomically diverse large fossil fauna skeletal remains sealed in the Pleistocene colluvial and alluvial-plain formations in intact geological positions 10-20 m above the present river and scattered on gravelly river banks after their erosion from the primary geo-contexts attest to a high biotic potential of the Late Pleistocene (MIS 3-2) sub-Arctic forest-tundra. Pollen records from the ancient interstratified boggy sediments and megafauna coprolites (14C-dated to 41-38 ka BP) show a predominance of the Siberian larch, dwarf birch and willow in the local vegetation cover accompanied by grassy communities during the mid-Last Glacial stage not dissimilar from the present northern taiga forest. Articulated and humanly used/worked fauna bones (mammoth, rhinoceros, horse, bison and reindeer among other species) point to co-existence of the large animals with the Upper Palaeolithic people within the mosaic open riverine ecosystems of the late Last Ice Age. The time-trangressive macro-lithic stone industry produced from pre-selected river gravel cobbles document some specific ways of human environmental adjustment to past periglacial settings. Geomorphology and hydrogeology indices of field mappings in congruence with the long-term statistical meteorology data illustrate a steadily increasing annual temperature trend in the broader Yana-Adycha Basins (current MAT -14.5°C) that triggers accelerated permafrost thaw across the Verkhoyansk Region of NE Siberia, particularly the lowlands, similarly as in the Indigirka and Kolyma Basins further East. The regional fluvial discharge is most dynamic during late spring due to the cumulative effects of snow

  7. Phenol degradation on Pr6O11 surface under UV-A light. Synergistic photocatalysis by semiconductors

    International Nuclear Information System (INIS)

    Karunakaran, C.; Dhanalakshmi, R.

    2009-01-01

    Phenol degrades on the surface of Pr 6 O 11 , an insulator, under UV-A light and the degradation rate increases linearly with phenol concentration and photon flux but decreases linearly with pH. The degradation efficiency is higher with UV-C light than with UV-A light. While TiO 2 , Fe 2 O 3 , CuO, ZnO, ZnS, Nb 2 O 5 and CdO particles individually photocatalyze the degradation each semiconductor exhibits synergistic effect, an enhanced photodegradation, when present along with Pr 6 O 11 suggesting hole-transfer from illuminated semiconductors to phenol adsorbed on Pr 6 O 11 during collision

  8. Nitrate and Moisture Content of Broad Permafrost Landscape Features in the Barrow Peninsula: Predicting Evolving NO3 Concentrations in a Changing Arctic

    Science.gov (United States)

    Arendt, C. A.; Heikoop, J. M.; Newman, B. D.; Wales, N. A.; McCaully, R. E.; Wilson, C. J.; Wullschleger, S.

    2017-12-01

    The geochemical evolution of Arctic regions as permafrost degrades, significantly impacts nutrient availability. The release of nitrogen compounds from permafrost degradation fertilizes both microbial decomposition and plant productivity. Arctic warming promotes permafrost degradation, causing geomorphic and hydrologic transitions that have the potential to convert saturated zones to unsaturated zones and subsequently alter the nitrate production capacity of permafrost regions. Changes in Nitrate (NO3-) content associated with shifting moisture regimes are a primary factor determining Arctic fertilization and subsequent primary productivity, and have direct feedbacks to carbon cycling. We have documented a broad survey of co-located soil moisture and nitrate concentration measurements in shallow active layer regions across a variety of topographic features in the expansive continuous permafrost region encompassing the Barrow Peninsula of Alaska. Topographic features of interest are slightly higher relative to surrounding landscapes with drier soils and elevated nitrate, including the rims of low centered polygons, the centers of flat and high centered polygons, the rims of young, old and ancient drain thaw lake basins and drainage slopes that exist across the landscape. With this information, we model the nitrate inventory of the Barrow Peninsula using multiple geospatial approaches to estimate total area cover by unsaturated features of interest and further predict how various drying scenarios increase the magnitude of nitrate produced in degrading permafrost regions across the Arctic. This work is supported by the US Department of Energy Next Generation Ecosystem Experiment, NGEE-Arctic.

  9. A review of published literature on the effects of permafrost on the hydrogeochemistry of bedrock

    International Nuclear Information System (INIS)

    Cascoyne, M.

    2000-06-01

    of seawater, enhanced or depleted sulphate concentrations in certain groundwaters, and lighter isotopic signature of the saline waters caused by the ice-water isotopic fractionation. This review has found that salt-rejection processes undoubtedly will have occurred in groundwaters in the marine sediments and bedrock of the Baltic coast during the Pleistocene. Deeply penetrating permafrost in the bedrock would cause relatively pure water to form as ice in fractures and displace residual saline fluids, under density flow, to greater depths. The process could have occurred to a sufficient extent that large volumes of saline water were generated, some of which may currently remain in the fractured rock. In these waters, loss of sulphate by mirabilite precipitation would be expected to have occurred but, on warming and degradation of the permafrost, lower-salinity meltwaters would re-dissolve the mirabilite, giving rise to a SO 4 -rich groundwater. This may be the origin of groundwater that is currently identified as Litorina Sea water at the Aespoe and Olkiluoto sites. This mechanism differs from that suggested by Israeli workers who propose freezing of open seawater and infiltration of residual brines into the bedrock followed by lateral migration inland. The hypothesis presented here, of formation of saline waters and brines by permafrost aggradation and salt-rejection is more acceptable from a hydrogeological standpoint because the saline waters are formed in situ and need not migrate laterally. Further field evidence, coupled with modelling of depths of permafrost penetration, could be used to assess the volume and concentration of saline groundwater formed as a result of downward advancement of permafrost in the crystalline bedrock. (orig.)

  10. A review of published literature on the effects of permafrost on the hydrogeochemistry of bedrock

    International Nuclear Information System (INIS)

    Gascoyne, M.

    2000-04-01

    , enhanced or depleted sulphate concentrations in certain groundwaters, and lighter isotopic signature of the saline waters caused by the ice-water isotopic fractionation. This review has found that salt-rejection processes undoubtedly will have occurred in groundwaters in the marine sediments and bedrock of the Baltic coast during the Pleistocene. Deeply penetrating permafrost in the bedrock would cause relatively pure water to form as ice in fractures and displace residual saline fluids,under density flow, to greater depths. The process could have occurred to a sufficient extent that large volumes of saline water were generated, some of which may currently remain in the fractured rock. In these waters,loss of sulphate by mirabilite precipitation would be expected to have occurred but, on warming and degradation of the permafrost,lower-salinity meltwaters would re-dissolve the mirabilite, giving rise to a SO 4 -rich groundwater. This may be the origin of groundwater that is currently identified as Litorina Sea water at the Aespoe and Olkiluoto sites. This mechanism differs from that suggested by Israeli workers who propose freezing of open seawater and infiltration of residual brines into the bedrock followed by lateral migration inland. The hypothesis presented here, of formation of saline waters and brines by permafrost aggradation and salt-rejection is more acceptable from a hydrogeological standpoint because the saline waters are formed in situ and need not migrate laterally. Further field evidence, coupled with modelling of depths of permafrost penetration, could be used to assess the volume and concentration of saline groundwater formed as a result of downward advancement of permafrost in the crystalline bedrock

  11. Relevance of mineral-organic associations in cryoturbated permafrost soils

    Science.gov (United States)

    Gentsch, Norman; Mikutta, Robert; Bárta, Jiří; Čapek, Petr; Gittel, Antje; Richter, Andreas; Šantrůčková, Hanna; Schnecker, Jörg; Shibistova, Olga; Urich, Tim; Wild, Birgit; Guggenberger, Georg

    2014-05-01

    Enhanced microbial decomposition of deep buried organic matter (OM) increase the release of CO2and CH4from high latitude ecosystems, thus being an uncertain but potentially crucial positive feedback to global warming. The role of soil minerals as stabilization agents of OM against microbial attack gain in importance as soon abiotic soil conditions will change in permafrost soils. We investigated changes in storage and turnover of soil organic carbon (OC) and total nitrogen (TN) associated with minerals in 27 cryoturbated permafrost soils from the west to the east Siberian Arctic. Furthermore, we studied the mineral composition and the potential of OM to interact with soil minerals via different binding mechanisms. Mineral-associated organic matter (MOM) was separated from particulate plant debris by density fractionation in sodium polytungstate (density cut-off 1.6 g cm-3). Their apparent 14C ages were determined by accelerator mass spectrometry and potential mineralization rates were analyzed in a 180 days incubation experiments at 5 and 15° C. The mineral composition was analyzed by X-ray diffraction and selective extractions. Desorption experiments (stepwise extraction with KCl and NaH2PO4) using the permafrost soils as well as reference soils from temperate regions (three Stagnolsols from Germany) were performed to study OM sorbed to mineral surfaces or complexed with polyvalent metal ions. The proportion of OC associated with minerals (MOC) ranged from 5.1 to 14.9 kg m-2 (average: 11.0 kg m-2), corresponding to ~55% from the total soil OC storage (average: 20.2 ± 8.0 kg m-2) in the first meter of the Cryosols. In contrast to temperate soils, where maximum MOC concentrations are present in topsoils, cambic, or spodic horizons, cryoturbation in permafrost soils leads to high MOC concentrations within the whole solum. Cryoturbated OM-rich pockets in the subsoil store 18% (2.0 ± 1.3 kg m-2) of the MOC while another 34% (3.8 ± 3.5 kg m-2) was located in the

  12. Recent Progress in Mountain Permafrost Modelling using BTS in North America

    Science.gov (United States)

    Bonnaventure, P. P.; Lewkowicz, A. G.

    2009-04-01

    This presentation reports on progress in mapping and modelling mountain permafrost in North America over the past 5 years using the Basal Temperature of Snow (BTS) technique. It describes the methodology and some of the challenges in our current study aimed at modelling permafrost at a resolution of 30 x 30 m, for the entire southern half of the Yukon Territory, an area of 250 x 103 km2. This mountainous region differs from those in Europe and Asia by having a sparse population, very limited base-line information (such as climate data) and relatively low levels of infrastructure. However, major infrastructure projects, such as pipelines, roads, railways and mines are being proposed and climate change is expected to affect permafrost distribution and characteristics, including potentially triggering landslides and other natural hazards. The research involves developing BTS-based models validated using late-summer ground-truthing. Models have been created for three areas and work is currently underway in five other locations in the Yukon with possible future sites in northern British Columbia. Work to date has examined the suitability of the method in differing climatic zones, the interchangeability of models between areas, and the potential effects of climatic change. Current data collection is focused on the potential impact of atmospheric temperature inversions on permafrost distribution: each of the study areas has been equipped with a network of air, ground surface and permafrost surface temperature sensors as well as snow-depth monitoring devices, located within different topographic situations. Another challenge is the interpolation of permafrost probabilities between distant study areas: information developed from a data-base of more than 1500 rock glaciers is expected to help in this regard. The project, which is scheduled for completion within the next 12 months, will provide essential information relating to the spatial attributes and sensitivities of

  13. Monitoring an Induced Permafrost Warming Experiment Using ERT, Temperature, and NMR in Fairbanks, Alaska

    Science.gov (United States)

    Ulrich, C.; Ajo Franklin, J. B.; Ekblaw, I.; Lindsey, N.; Wagner, A. M.; Saari, S.; Daley, T. M.; Freifeld, B. M.

    2016-12-01

    As global temperatures continue to rise, permafrost landscapes will experience more rapid changes than other global climate zones. Permafrost thaw is a result of increased temperatures in arctic settings resulting in surface deformation and subsurface hydrology changes. From an engineering perspective, surface deformation poses a threat to the stability of existing infrastructure such as roads, utility piping, and building structures. Preemptively detecting or monitoring subsurface thaw dynamics presents a difficult challenge due to the long time scales as deformation occurs. Increased subsurface moisture content results from permafrost thaw of which electrical resistivity tomography (ERT), soil temperature, and nuclear magnetic resonance (NMR) are directly sensitive. In this experiment we evaluate spatial and temporal changes in subsurface permafrost conditions (moisture content and temperature) at a experimental heating plot in Fairbanks, AK. This study focuses on monitoring thaw signatures using multiple collocated electrical resistivity (ERT), borehole temperature, and borehole nuclear magnetic resonance (NMR) measurements. Timelapse ERT (sensitive to changes in moisture content) was inverted using collocated temperature and NMR to constrain ERT inversions. Subsurface thermal state was monitored with timelapse thermistors, sensitive to soil ice content. NMR was collected in multiple boreholes and is sensitive to changes in moisture content and pore scale distribution. As permafrost thaws more hydrogen, in the form of water, is available resulting in a changing NMR response. NMR requires the availability of liquid water in order to induce spin of the hydrogen molecule, hence, if frozen water molecules will be undetectable. In this study, the permafrost is poised close to 0oC and is mainly silt with small pore dimensions; this combination makes NMR particularly useful due to the possibility of sub-zero thaw conditions within the soil column. Overall this

  14. The role of climate change in regulating Arctic permafrost peatland hydrological and vegetation change over the last millennium

    Science.gov (United States)

    Zhang, Hui; Piilo, Sanna R.; Amesbury, Matthew J.; Charman, Dan J.; Gallego-Sala, Angela V.; Väliranta, Minna M.

    2018-02-01

    Climate warming has inevitable impacts on the vegetation and hydrological dynamics of high-latitude permafrost peatlands. These impacts in turn determine the role of these peatlands in the global biogeochemical cycle. Here, we used six active layer peat cores from four permafrost peatlands in Northeast European Russia and Finnish Lapland to investigate permafrost peatland dynamics over the last millennium. Testate amoeba and plant macrofossils were used as proxies for hydrological and vegetation changes. Our results show that during the Medieval Climate Anomaly (MCA), Russian sites experienced short-term permafrost thawing and this induced alternating dry-wet habitat changes eventually followed by desiccation. During the Little Ice Age (LIA) both sites generally supported dry-hummock habitats, at least partly driven by permafrost aggradation. However, proxy data suggest that occasionally, MCA habitat conditions were drier than during the LIA, implying that evapotranspiration may create important additional eco-hydrological feedback mechanisms under warm conditions. All sites showed a tendency towards dry conditions as inferred from both proxies starting either from ca. 100 years ago or in the past few decades after slight permafrost thawing, suggesting that recent warming has stimulated surface desiccation rather than deeper permafrost thawing. This study shows links between two important controls over hydrology and vegetation changes in high-latitude peatlands: direct temperature-induced surface layer response and deeper permafrost layer-related dynamics. These data provide important backgrounds for predictions of Arctic permafrost peatlands and related feedback mechanisms. Our results highlight the importance of increased evapotranspiration and thus provide an additional perspective to understanding of peatland-climate feedback mechanisms.

  15. MECHANISTIC STUDIES OF SURFACE CATALYZED H2O2 DECOMPOSITION AND CONTAMINANT DEGRADATION IN THE PRESENCE OF SAND. (R823402)

    Science.gov (United States)

    This study examined the mechanism and kinetics of surface catalyzed hydrogen peroxide decomposition and degradation of contaminants in the presence of sand collected from an aquifer and a riverbed. Batch experiments were conducted using variable sand concentrations (0.2 to 1.0&nb...

  16. Priming-induced Changes in Permafrost Soil Organic Matter Decomposition

    Science.gov (United States)

    Pegoraro, E.; Schuur, E.; Bracho, R. G.

    2015-12-01

    Warming of tundra ecosystems due to climate change is predicted to thaw permafrost and increase plant biomass and litter input to soil. Additional input of easily decomposable carbon can alter microbial activity by providing a much needed energy source, thereby accelerating soil organic matter decomposition. This phenomenon, known as the priming effect, can increase CO2 flux from soil to the atmosphere. However, the extent to which this mechanism can decrease soil carbon stocks in the Arctic is unknown. This project assessed priming effects on permafrost soil collected from a moist acidic tundra site in Healy, Alaska. We hypothesized that priming would increase microbial activity by providing microbes with a fresh source of carbon, thereby increasing decomposition of old and slowly decomposing carbon. Soil from surface and deep layers were amended with multiple pulses of uniformly 13C labeled glucose and cellulose, and samples were incubated at 15° C to quantify whether labile substrate addition increased carbon mineralization. We quantified the proportion of old carbon mineralization by measuring 14CO2. Data shows that substrate addition resulted in higher respiration rates in amended soils; however, priming was only observed in deep layers, where 30% more soil-derived carbon was respired compared to control samples. This suggests that microbes in deep layers are limited in energy, and the addition of labile carbon increases native soil organic matter decomposition, especially in soil with greater fractions of slowly decomposing carbon. Priming in permafrost could exacerbate the effects of climate change by increasing mineralization rates of carbon accumulated over the long-term in deep layers. Therefore, quantifying priming effect in permafrost soils is imperative to understanding the dynamics of carbon turnover in a warmer world.

  17. Monte Carlo Technique Used to Model the Degradation of Internal Spacecraft Surfaces by Atomic Oxygen

    Science.gov (United States)

    Banks, Bruce A.; Miller, Sharon K.

    2004-01-01

    Atomic oxygen is one of the predominant constituents of Earth's upper atmosphere. It is created by the photodissociation of molecular oxygen (O2) into single O atoms by ultraviolet radiation. It is chemically very reactive because a single O atom readily combines with another O atom or with other atoms or molecules that can form a stable oxide. The effects of atomic oxygen on the external surfaces of spacecraft in low Earth orbit can have dire consequences for spacecraft life, and this is a well-known and much studied problem. Much less information is known about the effects of atomic oxygen on the internal surfaces of spacecraft. This degradation can occur when openings in components of the spacecraft exterior exist that allow the entry of atomic oxygen into regions that may not have direct atomic oxygen attack but rather scattered attack. Openings can exist because of spacecraft venting, microwave cavities, and apertures for Earth viewing, Sun sensors, or star trackers. The effects of atomic oxygen erosion of polymers interior to an aperture on a spacecraft were simulated at the NASA Glenn Research Center by using Monte Carlo computational techniques. A two-dimensional model was used to provide quantitative indications of the attenuation of atomic oxygen flux as a function of the distance into a parallel-walled cavity. The model allows the atomic oxygen arrival direction, the Maxwell Boltzman temperature, and the ram energy to be varied along with the interaction parameters of the degree of recombination upon impact with polymer or nonreactive surfaces, the initial reaction probability, the reaction probability dependence upon energy and angle of attack, degree of specularity of scattering of reactive and nonreactive surfaces, and the degree of thermal accommodation upon impact with reactive and non-reactive surfaces to be varied to allow the model to produce atomic oxygen erosion geometries that replicate actual experimental results from space. The degree of

  18. Review article: Inferring permafrost and permafrost thaw in the mountains of the Hindu Kush Himalaya region

    Science.gov (United States)

    Gruber, Stephan; Fleiner, Renate; Guegan, Emilie; Panday, Prajjwal; Schmid, Marc-Olivier; Stumm, Dorothea; Wester, Philippus; Zhang, Yinsheng; Zhao, Lin

    2017-01-01

    The cryosphere reacts sensitively to climate change, as evidenced by the widespread retreat of mountain glaciers. Subsurface ice contained in permafrost is similarly affected by climate change, causing persistent impacts on natural and human systems. In contrast to glaciers, permafrost is not observable spatially and therefore its presence and possible changes are frequently overlooked. Correspondingly, little is known about permafrost in the mountains of the Hindu Kush Himalaya (HKH) region, despite permafrost area exceeding that of glaciers in nearly all countries. Based on evidence and insight gained mostly in other permafrost areas globally, this review provides a synopsis on what is known or can be inferred about permafrost in the mountains of the HKH region. Given the extreme nature of the environment concerned, it is to be expected that the diversity of conditions and phenomena encountered in permafrost exceed what has previously been described and investigated. We further argue that climate change in concert with increasing development will bring about diverse permafrost-related impacts on vegetation, water quality, geohazards, and livelihoods. To better anticipate and mitigate these effects, a deepened understanding of high-elevation permafrost in subtropical latitudes as well as the pathways interconnecting environmental changes and human livelihoods are needed.

  19. Application of a simple first-order, non-linear rainfall-runoff model in watersheds of varying permafrost coverage

    Science.gov (United States)

    Bolton, W. Robert; Hinzman, Larry

    2010-05-01

    The arctic and sub-arctic environments can be characterized as being in the zones continuous and discontinuous permafrost. Although the distribution of permafrost in these regions is site specific, it is the major control on many of the hydrologic processes including stream flow, soil moisture dynamics, and water storage processes. In areas underlain by permafrost, ice-rich soils a the permafrost table inhibit surface water percolation to the deep subsurface soils, resulting in an increased runoff generation during precipitation events (including snow melt), decreased baseflow between precipitation events, and relatively wetter soils compared to permafrost-free areas. Over the course of a summer season, the thawing of the active layer (the thin soil layer above the permafrost that seasonally freezes and thaws) increases the potential water holding capacity of the soil, resulting in a decreasing surface water contribution during precipitation events and a steadily increasing baseflow between precipitation events. The major challenge to hydrologic modeling in permafrost affected environments is accounting for the rapid spatial and temporal changes in the soil storage component with the thawing and freezing of the active layer and distribution of permafrost. Simulation of the storage storage component is further complicated as many of the variables that control the development of the active layer (and permafrost distribution) are not easily measurable beyond the point scale. Examples of these variables include soil material, soil moisture content, soil ice content, snow cover and depth, and surface temperature. Kirchner (2009) describes a method in which the total storage of a watershed can be derived directly from discharge measurements - the only hydrologic process that is easily measured at the watershed scale. Following the general procedure outlined by Kirchner, a simple rainfall-runoff model was developed and applied to basins of various scales and permafrost

  20. Optimization of photocatalytic degradation of real textile dye house wastewater by response surface methodology.

    Science.gov (United States)

    Hosseini, Sayed Mohammad Bagher; Fallah, Narges; Royaee, Sayed Javid

    2016-11-01

    This study evaluates the advanced oxidation process for decolorization of real textile dyeing wastewater containing azo and disperse dye by TiO 2 and UV radiation. Among effective parameters on the photocatalytic process, effects of three operational parameters (TiO 2 concentration, initial pH and aeration flow rate) were examined with response surface methodology. The F-value (136.75) and p-value degradation and subsequent analysis of variance (ANOVA) test using Design Expert software, the concentration of catalyst was found to be the most influential factor, while all the other factors were also significant. To achieve maximum dye removal, optimum conditions were found at TiO 2 concentration of 3 g L -1 , initial pH of 7 and aeration flow rate of 1.50 L min -1 . Under the conditions stated, the percentages of dye and chemical oxygen demand removal were 98.50% and 91.50%, respectively. Furthermore, the mineralization test showed that total organic compounds removal was 91.50% during optimum conditions.

  1. The Influence of Surface Alumina and Silica on the Photocatalytic Degradation of Organic Pollutants

    Directory of Open Access Journals (Sweden)

    Terry A. Egerton

    2013-03-01

    Full Text Available Practical photocatalysis for degradation of organic pollutants must take into account the influence of other chemicals. Significant Al deposition on titania can occur at naturally occurring concentrations of dissolved Al. This paper reviews the author’s work on the influence of deliberately deposited hydrous oxides of aluminium on the behavior of a ~130 m2 g−1 rutile TiO2, and then compares the behavior of deposited alumina with that of deposited silica. On rutile some adsorbed nitrogen is infrared-active. Alumina and silica deposited on the rutile reduce, and ultimately eliminate, this infrared-active species. They also reduce photocatalytic oxidation of both propan-2-ol and dichloroacetate ion and the photocatalytic reduction of diphenyl picryl hydrazine. The surface oxides suppress charge transfer and may also reduce reactant adsorption. Quantitative measurement of TiO2 photogreying shows that the adsorbed inorganics also reduce photogreying, attributed to the capture of photogenerated conduction band electrons by Ti4+ to form Ti3+. The influence of adsorbed phosphate on photocatalysis is briefly considered, since phosphate reduces photocatalytic disinfection. In the context of classical colloid studies, it is concluded that inorganic species in water can significantly reduce photoactivity from the levels that measured in pure water.

  2. Degradation Potential of Bulk Versus Incrementally Applied and Indirect Composites: Color, Microhardness, and Surface Deterioration.

    Science.gov (United States)

    El Gezawi, M; Kaisarly, D; Al-Saleh, H; ArRejaie, A; Al-Harbi, F; Kunzelmann, K H

    This study investigated the color stability and microhardness of five composites exposed to four beverages with different pH values. Composite discs were produced (n=10); Filtek Z250 (3M ESPE) and Filtek P90 (3M ESPE) were applied in two layers (2 mm, 20 seconds), and Tetric N-Ceram Bulk Fill (TetricBF, Ivoclar Vivadent) and SonicFill (Kerr) were applied in bulk (4 mm) and then light cured (40 seconds, Ortholux-LED, 1600 mW/cm 2 ). Indirect composite Sinfony (3M ESPE) was applied in two layers (2 mm) and cured (Visio system, 3M ESPE). The specimens were polished and tested for color stability; ΔE was calculated using spectrophotometer readings. Vickers microhardness (50 g, dwell time=45 seconds) was assessed on the top and bottom surfaces at baseline, 40 days of storage, subsequent repolishing, and 60 days of immersion in distilled water (pH=7.0), Coca-Cola (pH=2.3), orange juice (pH=3.75), or anise (pH=8.5) using scanning electron microscopy (SEM). The materials had similar ΔE values (40 days, p>0.05), but TetricBF had a significantly greater ΔE than P90 or SF (40 days). The ΔE was less for P90 and TetricBF than for Z250, SonicFill, and Sinfony (60 days). Repolishing and further immersion significantly affected the ΔE (pBulk-fill composites differ regarding color-stability and top-to-bottom microhardness changes compared with those of other composites. P90 showed better surface degradation resistance. In conclusion, bulk-fill composites are not promising alternatives to incremental and indirect composites regarding biodegradation.

  3. On the degradation of fuel cell catalyst. From model systems to high surface area catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Arenz, M. [Copenhagen Univ. (Denmark). Dept. of Chemistry

    2010-07-01

    In the presented work, as an alternative accelerated degradation tests in the form of half-cell measurements combined with identical location transmission electron microscopy (IL-TEM){sup 10,} {sup 11} are presented. It is demonstrated that for different catalysts the degradation mechanism can be scrutinized in detail. Thus this approach enables the systematic investigation of fuel cell catalyst degradation in a reduced period of time. (orig.)

  4. Analysing the environmental harms caused by coal mining and its protection measures in permafrost regions of Qinghai–Tibet Plateau

    Directory of Open Access Journals (Sweden)

    Wei Cao

    2017-09-01

    Full Text Available The coal mining has brought a series of ecological problems and environmental problems in permafrost regions. Taking Muli coal-mining area as an example, this article attempts to analyse the environmental harms caused by coal mining and its protection measures in permafrost regions of Qinghai–Tibet Plateau. This article analyses the influence of open mining on the surrounding permafrost around the open pit by using the numerical simulation. The results show that (1 based on the interrelation between coal mining and permafrost environment, these main environmental harm include the permafrost change and the natural environment change in cold regions; (2 once the surface temperature rises due to open mining, the permafrost will disappear with the increase of exploitation life. If considering the solar radiation, the climate conditions and the geological condition around the pit edge, the maximum thaw depth will be more than 2 m; (3 the protection measures are proposed to avoid the disadvantage impact on the permafrost environment caused by coal mining. It will provide a scientific basis for the resource development and environment protection in cold regions.

  5. Daylight-driven photocatalytic degradation of ionic dyes with negatively surface-charged In2S3 nanoflowers: dye charge-dependent roles of reactive species

    Science.gov (United States)

    Ge, Suxiang; Cai, Lejuan; Li, Dapeng; Fa, Wenjun; Zhang, Yange; Zheng, Zhi

    2015-12-01

    Even though dye degradation is a successful application of semiconductor photocatalysis, the roles of reactive species in dye degradation have not received adequate attention. In this study, we systematically investigated the degradation of two cationic dyes (rhodamine B and methylene blue) and two anionic dyes (methyl orange and orange G) over negatively surface-charged In2S3 nanoflowers synthesized at 80 °C under indoor daylight lamp irradiation. It is notable to find In2S3 nanoflowers were more stable in anionic dyes degradation compared to that in cationic dyes removal. The active species trapping experiments indicated photogenerated electrons were mainly responsible for cationic dyes degradation, but holes were more important in anionic dyes degradation. A surface-charge-dependent role of reactive species in ionic dye degradation was proposed for revealing such interesting phenomenon. This study would provide a new insight for preparing highly efficient daylight-driven photocatalyst for ionic dyes degradation.

  6. Surface degradation of glass ceramics after exposure to acidulated phosphate fluoride

    Science.gov (United States)

    CCAHUANA, Vanessa Zulema S.; ÖZCAN, Mutlu; MESQUITA, Alfredo Mikail Melo; NISHIOKA, Renato Sussumo; KIMPARA, Estevão Tomomitsu; BOTTINO, Marco Antonio

    2010-01-01

    Objective This study evaluated the surface degradation effect of acidulated phosphate fluoride (APF) gel exposure on the glassy matrix ceramics as a function of time. Material and methods Disc-shaped ceramic specimens (N = 120, 10/per ceramic material) were prepared in stainless steel molds (inner diameter: 5 mm, height: 2 mm) using 6 dental ceramics: 3 indicated for ceramic-fused-to-metal (Vita Omega 900, Carmen and Vita Titankeramik), 2 for all-ceramic (Vitadur Alpha and Finesse® Low Fusing) and 1 for both types of restorations (IPS d.SIGN). The specimens were wet ground finished, ultrasonically cleaned and auto-glazed. All specimens were subjected to calculation of percentage of mass loss, surface roughness analysis and topographical description by scanning electron microscopy (SEM) before (0 min) and after exposure to 1.23 % APF gel for 4 min and 60 min representing short- and long-term etching effect, respectively. The data were analyzed using two-way ANOVA with repeated measures and Tukey`s test (α=0.05). Results Significant effect of the type of the ceramics (p=0.0000, p=0.0031) and exposure time (p=0.0000) was observed in both surface roughness and percentage of mass loss values, respectively. The interaction factor between both parameters was also significant for both parameters (p=0.0904, p=0.0258). Both 4 min (0.44±0.1 - 0.81±0.2 µm) and 60 min (0.66±0.1 - 1.04±0.3 µm) APF gel exposure created significantly more surface roughness for all groups when compared to the control groups (0.33±0.2 - 0.68±0.2 µm) (p0.05) but at 60 min exposure, IPS d.SIGN showed the highest percentage of mass loss (0.1151±0.11). The mean surface roughness for Vita Titankeramik (0.84±0.2 µm) and Finesse® Low Fusing (0.74.±0.2 µm) was significantly higher than those of the other ceramics (0.59±0.1 µm - 0.49±0.1 µm) and Vita Titankeramik (p<0.05) regardless of the exposure time. A positive correlation was found between surface roughness and percentage of mass

  7. Optimization of phenol degradation by Candida tropicalis Z-04 using Plackett-Burman design and response surface methodology.

    Science.gov (United States)

    Zhou, Jiangya; Yu, Xiaojuan; Ding, Cong; Wang, Zhiping; Zhou, Qianqian; Pao, Hao; Cai, Weimin

    2011-01-01

    Statistical experimental designs were used to optimize the process of phenol degradation by Candida tropicalis Z-04, isolated from phenol-degrading aerobic granules. The most important factors influencing phenol degradation (p Plackett-Burman design with 11 variables, were yeast extract, phenol, inoculum size, and temperature. Steepest ascent method was undertaken to determine the optimal regions of these four significant factors. Central composite design (CCD) and response surface analysis were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum phenol degradation. The analysis results indicated that interactions between yeast extract and temperature, phenol and temperature, inoculum size and temperature affected the response variable (phenol degradation) significantly. The predicted results showed that the maximum removal efficiency of phenol (99.10%) could be obtained under the optimum conditions of yeast extract 0.41 g/L, phenol 1.03 g/L, inoculum size 1.43% (V/V) and temperature 30.04 degrees C. These predicted values were further verified by validation experiments. The excellent correlation between predicted and experimental values confirmed the validity and practicability of this statistical optimum strategy. This study indicated the excellent ability of C. tropicalis Z-04 in degrading high-strength phenol. Optimal conditions obtained in this experiment laid a solid foundation for further use of this microorganism in the treatment of high-strength phenol effluents.

  8. Carbon loss and chemical changes from permafrost collapse in the northern Tibetan Plateau

    Science.gov (United States)

    Mu, Cuicui; Zhang, Tingjun; Zhang, Xiankai; Li, Lili; Guo, Hong; Zhao, Qian; Cao, Lin; Wu, Qingbai; Cheng, Guodong

    2016-07-01

    Permafrost collapse, known as thermokarst, can alter soil properties and carbon emissions. However, little is known regarding the effects of permafrost collapse in upland landscapes on the biogeochemical processes that affect carbon balance. In this study, we measured soil carbon and physiochemical properties at a large thermokarst feature on a hillslope in the northeastern Tibetan Plateau. We categorized surfaces into three different microrelief patches based on type and extent of collapse (control, drape, and exposed areas). Permafrost collapse resulted in substantial decreases of surface soil carbon and nitrogen stocks, with losses of 29.6 ± 4.2% and 28.9 ± 3.1% for carbon and nitrogen, respectively, in the 0-10 cm soil layer. Laboratory incubation experiments indicated that control soil had significantly higher CO2 production rates than that of drapes. The results from Fourier transform infrared spectroscopy analysis showed that exposed soils accumulated some organic matter due to their low position within the feature, which was accompanied by substantial changes in the chemical structure and characteristics of the soil carbon. Exposed soils had higher hydrocarbon and lignin/phenol backbone content than in control and drape soils in the 0-10 cm layer. This study demonstrates that permafrost collapse can cause abundant carbon and nitrogen loss, potentially from mineralization, leaching, photodegradation, and lateral displacement. These results demonstrate that permafrost collapse redistributes the soil organic matter, changes its chemical characteristics, and leads to losses of organic carbon due to the greenhouse gas emission.

  9. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Richard Sigal; Kent Newsham; Thomas Williams; Barry Freifeld; Timothy Kneafsey; Carl Sondergeld; Shandra Rai; Jonathan Kwan; Stephen Kirby; Robert Kleinberg; Doug Griffin

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. The work scope drilled and cored a well The Hot Ice No. 1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report. The Hot Ice No. 1 well was drilled from the surface to a measured depth of 2300 ft. There was almost 100% core recovery from the bottom of surface casing at 107 ft to total depth. Based on the best estimate of the bottom of the methane hydrate stability zone (which used new data obtained from Hot Ice No. 1 and new analysis of data from adjacent wells), core was recovered over its complete range. Approximately 580 ft of porous, mostly frozen, sandstone and 155 of conglomerate were recovered in the Ugnu Formation and approximately 215 ft of porous sandstone were recovered in the West Sak Formation. There were gas shows in the bottom

  10. Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, Benjamin; Jones, Jeremy B.; Schuur, Edward A.; Chapin, F. S.; Bowden, William B.; Bret-Harte, M. Syndonia; Epstein, Howard E.; Flannigan, Michael D.; Harms, Tamara K.; Hollingsworth, Teresa N.; Mack, Michelle; McGuire, A. David; Natali, Susan M.; Rocha, Adrian; Tank, Suzanne E.; Turetsky, Merritt; Vonk, Jorien E.; Wickland, Kimberly P.; Aiken, George R.; Alexander, Heather D.; Amon, Rainer M.; Benscoter, Brian W.; Bergeron, Yves; Bishop, Kevin; Blarquez, Olivier; Bond-Lamberty, Benjamin; Breen, Amy L.; Buffam, Ishi; Cai, Yihua; Carcaillet, Christopher; Carey, Sean K.; Chen, Jing Ming; Chen, Han Y.; Christensen, Torben R.; Cooper, Lee W.; Cornelissen, J Hans C.; de Groot, William J.; DeLuca, Thomas H.; Dorrepaal, Ellen; Fetcher, Ned; Finlay, Jacques C.; Forbes, Bruce C.; French, Nancy H.; Gauthier, Sylvie; Girardin, Martin P.; Goetz, Scott J.; Goldammer, Johann G.; Gough, Laura; Grogan, Paul; Guo, Laodong; Higuera, Philip E.; Hinzman, Larry; Hu, Feng S.; Hugelius, Gustaf; Jafarov, Elchin E.; Jandt, Randi; Johnstone, Jill F.; Karlsson, J.; Kasischke, Eric S.; Kattner, Gerhard; Kelly, Ryan; Keuper, Frida; Kling, George; Kortelainen, Pirkko; Kouki, Jari; Kuhry, Peter; Laudon, Hjalmar; Laurion, Isabelle; Macdonald, Robie W.; Mann, Paul J.; Martikainen, Pertti; McClelland, James W.; Molau, Ulf; Oberbauer, Steven F.; Olefeldt, David; Pare, David; Parisien, Marc-Andre; Payette, Serge; Peng, Changhui; Pokrovesky, Oleg S.; Rastetter, Edward B.; Raymond, Peter A.; Raynolds, Martha K.; Rein, Guillermo; Reynolds, James F.; Robards, Martin; Rogers, Brendan M.; Schadel, Christina; Schaefer, Kevin; Schmidt, Inger K.; Shvidenko, Anatoly; Sky, Jasper; Spencer, Robert G.; Starr, Gregory; Striegl, Robert G.; Teisserenc, Roman; Tranvik, Lars J.; Virtanen, Tarmo; Welker, Jeffrey M.; Zimov, Sergei

    2016-03-07

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

  11. Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment

    Science.gov (United States)

    Benjamin W. Abbott,; Jeremy B. Jones,; Edward A.G. Schuur,; F.S. Chapin, III; Bowden, William B.; M. Syndonia Bret-Harte,; Howard E. Epstein,; Michael D. Flannigan,; Tamara K. Harms,; Teresa N. Hollingsworth,; Mack, Michelle C.; McGuire, A. David; Susan M. Natali,; Adrian V. Rocha,; Tank, Suzanne E.; Merrit R. Turetsky,; Jorien E. Vonk,; Wickland, Kimberly P.; Aiken, George R.

    2016-01-01

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

  12. Permafrost Map of Alaska, USA, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of a geo-referenced digital map and attribute data derived from the publication 'Permafrost map of Alaska'. The map is presented at a scale of...

  13. Permafrost Meta-Omics and Climate Change

    DEFF Research Database (Denmark)

    Mackelprang, Rachel; Saleska, Scott R.; Jacobsen, Carsten Suhr

    2016-01-01

    from thawing permafrost regions. Analysis of nucleic acids and proteins taken directly from permafrost-associated soils has provided new insights into microbial communities and their functions in Arctic environments that are increasingly impacted by climate change. In this article we review current...... carbon produce carbon dioxide and other greenhouse gases, contributing substantially to climate change. Next-generation sequencing and other -omics technologies offer opportunities to discover the mechanisms by which microbial communities regulate the loss of carbon and the emission of greenhouse gases...... information from various molecular -omics studies on permafrost microbial ecology and explore the relevance of these insights to our current understanding of the dynamics of permafrost loss due to climate change....

  14. The Effects of Perchlorates on the Permafrost Methanogens: Implication for Autotrophic Life on Mars.

    Science.gov (United States)

    Shcherbakova, Viktoria; Oshurkova, Viktoria; Yoshimura, Yoshitaka

    2015-09-09

    The terrestrial permafrost represents a range of possible cryogenic extraterrestrial ecosystems on Earth-like planets without obvious surface ice, such as Mars. The autotrophic and chemolithotrophic psychrotolerant methanogens are more likely than aerobes to function as a model for life forms that may exist in frozen subsurface environments on Mars, which has no free oxygen, inaccessible organic matter, and extremely low amounts of unfrozen water. Our research on the genesis of methane, its content and distribution in permafrost horizons of different ages and origin demonstrated the presence of methane in permanently frozen fine-grained sediments. Earlier, we isolated and described four strains of methanogenic archaea of Methanobacterium and Methanosarcina genera from samples of Pliocene and Holocene permafrost from Eastern Siberia. In this paper we study the effect of sodium and magnesium perchlorates on growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. In this paper we study the effect of sodium and magnesium perchlorates on the growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. Furthermore, as shown in the studies strain M2(T) M. arcticum, probably can use perchlorate anion as an electron acceptor in anaerobic methane oxidation. Earth's subzero subsurface environments are the best approximation of environments on Mars, which is most likely to harbor methanogens; thus, a biochemical understanding of these pathways is expected to provide a basis for designing experiments to detect autotrophic methane-producing life forms on Mars.

  15. The Effects of Perchlorates on the Permafrost Methanogens: Implication for Autotrophic Life on Mars

    Directory of Open Access Journals (Sweden)

    Viktoria Shcherbakova

    2015-09-01

    Full Text Available The terrestrial permafrost represents a range of possible cryogenic extraterrestrial ecosystems on Earth-like planets without obvious surface ice, such as Mars. The autotrophic and chemolithotrophic psychrotolerant methanogens are more likely than aerobes to function as a model for life forms that may exist in frozen subsurface environments on Mars, which has no free oxygen, inaccessible organic matter, and extremely low amounts of unfrozen water. Our research on the genesis of methane, its content and distribution in permafrost horizons of different ages and origin demonstrated the presence of methane in permanently frozen fine-grained sediments. Earlier, we isolated and described four strains of methanogenic archaea of Methanobacterium and Methanosarcina genera from samples of Pliocene and Holocene permafrost from Eastern Siberia. In this paper we study the effect of sodium and magnesium perchlorates on growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. In this paper we study the effect of sodium and magnesium perchlorates on the growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. Furthermore, as shown in the studies strain M2T M. arcticum, probably can use perchlorate anion as an electron acceptor in anaerobic methane oxidation. Earth’s subzero subsurface environments are the best approximation of environments on Mars, which is most likely to harbor methanogens; thus, a biochemical understanding of these pathways is expected to provide a basis for designing experiments to detect autotrophic methane-producing life forms on Mars.

  16. Arctic ecosystem reaction on permafrost melting as a result of 40 years anthropogenic impact

    Science.gov (United States)

    Petrzhik, Nataliya; Matyshak, George; Myshonkov, Alexander; Petrov, Dmitry

    2017-04-01

    Arctic ecosystems are sensitive indicators of environmental change. The increasing of anthropogenic impact perturb the natural ecosystems balance, first of all significant changes happen in soil and vegetation. It is necessary to study the permafrost ecosystem response, as the permafrost covers the quarter of the world and more than a half of Russia. Since 1960 the oil and gas industry grows in Russia. The hydrocarbons can be transferred by pipelines only in the heated state. The main effect of construction and operation of pipeline is the heating of soil and permafrost degradation. The goal of this study was to estimate the response of landscapes and permafrost ecosystem of north of West Siberia to the cumulative action of pipelines. The main objective was to investigate the warming impact on the properties and function of the soil along the pipelines in permafrost zone. The studied object was vegetation and soil cover of the north of Western Siberia ecosystems after the action of pipelines. The areas with maximum effect of heat lines were selected by remote sensing. Ten transects of 50 meters in length with sampling points every 5 meters from pipeline to undisturbed background area were selected in three different natural zones. The soil and vegetation cover was described, sampled, active layer of soil and the power of organic horizon were measured, the hydrothermal regime of soils in a layer of 0-10 cm was measured, the emission of greenhouse gas was studied. In the laboratory, the content of labile carbon, microbial biomass carbon, basal and substrate-induced respiration were measured. The main effect of the pipelines impact is the active degradation of permafrost and changes in hydrothermal settings. From background to broken areas the following settings changing: the depth of thawing increase in 10 times; the soil temperature changes from 4 to 10,5 ° C in taiga, from 4.5 to 13,5 ° C in tundra, from 5.5 to 12 ° C in forest-tundra; the soil moisture reduces

  17. Bioavailability of soil organic matter and microbial community dynamics upon permafrost thaw.

    Science.gov (United States)

    Coolen, Marco J L; van de Giessen, Jeroen; Zhu, Elizabeth Y; Wuchter, Cornelia

    2011-08-01

    Amplified Arctic warming could thaw 25% of the permafrost area by 2100, exposing vast amounts of currently fixed organic carbon to microbially mediated decomposition and release of greenhouse gasses through soil organic matter (SOM) respiration. We performed time-series incubation experiments with Holocene permafrost soils at 4°C for up to 11 days to determine changes in exoenzyme activities (EEAs) (i.e. phosphatase, β-glucosidase, aminopeptidase) as a measure for the bioavailability of SOM in response to permafrost thaw. We also profiled SSU rRNA transcripts to follow the qualitative and quantitative changes in viable prokaryotes and eukaryotes during incubation. EEA, amount of rRNA transcripts and microbial community structures differed substantially between the various soil intervals in response to thaw: after 11 days of incubation, the active layer became slightly depleted in C and P and harboured bacterial phyla indicative of more oligotrophic conditions (Acidobacteria). A fast response in phosphatase and β-glucosidase upon thaw, and a predominance of active copiotrophic Bacteroidetes, showed that the upper permafrost plate serves as storage of easily degradable carbon derived from the overlying thawed active layer during summer. EEA profiles and microbial community dynamics furthermore suggest that the deeper and older permafrost intervals mainly contain recalcitrant SOM, and that extracellular soil-bound exoenzymes play a role in the initial cleavage of biopolymers, which could kick-start microbial growth upon thaw. Basidiomycetous fungi and Candidate Subdivision OP5 bacteria were the first to respond in freshly thawed deeper permafrost intervals, and might play an important role in the decomposition of recalcitrant SOM to release more labile substrates to support the major bacterial phyla (β-Proteobacteria, Actinobacteria, Firmicutes), which predominated thereafter. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  18. Metagenomic analysis of a permafrost microbial community reveals a rapid response to thaw

    Science.gov (United States)

    MacKelprang, R.; Waldrop, M.P.; Deangelis, K.M.; David, M.M.; Chavarria, K.L.; Blazewicz, S.J.; Rubin, E.M.; Jansson, J.K.

    2011-01-01

    Permafrost contains an estimated 1672????????Pg carbon (C), an amount roughly equivalent to the total currently contained within land plants and the atmosphere. This reservoir of C is vulnerable to decomposition as rising global temperatures cause the permafrost to thaw. During thaw, trapped organic matter may become more accessible for microbial degradation and result in greenhouse gas emissions. Despite recent advances in the use of molecular tools to study permafrost microbial communities, their response to thaw remains unclear. Here we use deep metagenomic sequencing to determine the impact of thaw on microbial phylogenetic and functional genes, and relate these data to measurements of methane emissions. Metagenomics, the direct sequencing of DNA from the environment, allows the examination of whole biochemical pathways and associated processes, as opposed to individual pieces of the metabolic puzzle. Our metagenome analyses reveal that during transition from a frozen to a thawed state there are rapid shifts in many microbial, phylogenetic and functional gene abundances and pathways. After one week of incubation at 5 ??C, permafrost metagenomes converge to be more similar to each other than while they are frozen. We find that multiple genes involved in cycling of C and nitrogen shift rapidly during thaw. We also construct the first draft genome from a complex soil metagenome, which corresponds to a novel methanogen. Methane previously accumulated in permafrost is released during thaw and subsequently consumed by methanotrophic bacteria. Together these data point towards the importance of rapid cycling of methane and nitrogen in thawing permafrost. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  19. International student Arctic Field School on Permafrost and urban areas study

    Science.gov (United States)

    Suter, L.; Tolmanov, V. A.; Grebenets, V. I.; Streletskiy, D. A.; Shiklomanov, N. I.

    2017-12-01

    related to permafrost degradation. The course represents an ongoing success in international multidisciplinary research through education resulting in building capacity of new generation of scholars with specialization on the Arctic regions.

  20. Application of response surface methodology for degradation of methyl orange with TiO2 sol-gel sulphated Ti

    International Nuclear Information System (INIS)

    Del Angel S, M. T.; Garcia A, R.; Garcia A, P.; Lagunes G, L. M.; Cabrera C, E. G.

    2015-01-01

    In this work we report the implementation of the response surface methodology for the optimization of photo catalytic degradation of methyl orange dye (MO) using as photo catalyst sulphated TiO 2 prepared by sol-gel method. The variables studied were ph of the solution (3-11), catalyst concentration (0.1-1 g/L), and MO concentration (10-30 ppm). The effects of these parameters over the degradation of MO were evaluated according to a Box-Behnken design. The only crystal structure identified by X-ray diffraction was anatase phase. The optimum conditions for the photo catalytic degradation of MO according to the methodology applied were ph 6.0, 17.78 ppm MO concentration at each concentration level of the catalyst. (Author)

  1. Modelling high Arctic deep permafrost temperature sensitivity in Northeast Greenland based on experimental and field observations

    Science.gov (United States)

    Rasmussen, Laura Helene; Zhang, Wenxin; Hollesen, Jørgen; Cable, Stefanie; Hvidtfeldt Christiansen, Hanne; Jansson, Per-Erik; Elberling, Bo

    2017-04-01

    Permafrost affected areas in Greenland are expected to experience a marked temperature increase within decades. Most studies have considered near-surface permafrost sensitivity, whereas permafrost temperatures below the depths of zero annual amplitude is less studied despite being closely related to changes in near-surface conditions, such as changes in active layer thermal properties, soil moisture and snow depth. In this study, we measured the sensitivity of thermal conductivity (TC) to gravimetric water content (GWC) in frozen and thawed permafrost sediments from fine-sandy and gravelly deltaic and fine-sandy alluvial deposits in the Zackenberg valley, NE Greenland. We further calibrated a coupled heat and water transfer model, the "CoupModel", for one central delta sediment site with average snow depth and further forced it with meteorology from a nearby delta sediment site with a topographic snow accumulation. With the calibrated model, we simulated deep permafrost thermal dynamics in four 20-year scenarios with changes in surface temperature and active layer (AL) soil moisture: a) 3 °C warming and AL water table at 0.5 m depth; b) 3 °C warming and AL water table at 0.1 m depth; c) 6 °C warming and AL water table at 0.5 m depth and d) 6 °C warming and AL water table at 0.1 m depth. Our results indicate that frozen sediments have higher TC than thawed sediments. All sediments show a positive linear relation between TC and soil moisture when frozen, and a logarithmic one when thawed. Gravelly delta sediments were highly sensitive, but never reached above 12 % GWC, indicating a field effect of water retention capacity. Alluvial sediments are less sensitive to soil moisture than deltaic (fine and coarse) sediments, indicating the importance of unfrozen water in frozen sediment. The deltaic site with snow accumulation had 1 °C higher mean annual ground temperature than the average snow depth site. Permafrost temperature at the depth of 18 m increased with 1

  2. The effect of permafrost thaw on short- and long-term carbon accumulation in permafrost mires

    Science.gov (United States)

    Olid, Carolina; Klaminder, Jonatan; Monteux, Sylvain; Johansson, Margareta; Dorrepaal, Ellen

    2017-04-01

    Permafrost stores twice as much carbon (C) as is currently present in the atmosphere. During recent years, warmer temperatures in the Arctic has caused rapid thawing of permafrost, which have dramatically altered permafrost C storage by increasing both microbial decomposition and plant productivity. Although current research focuses on the effects of climate change on these two processes, there are still no scientific consensus about the magnitude or even the direction of future C feedbacks from permafrost ecosystems. Field manipulation experiments have been widely used during the last decade to improve our knowledge about the net effects of permafrost thaw in the permafrost C storage. However, due to the slow response (decades) of permafrost ecosystems to environmental changes and the short-time nature of these experiments (usually shorter than 5-9 years), there are still concerns when attempting to extrapolate the results to predict long term effects. In addition, measurements are mostly taken exclusively during the summer season, without taking into account inter-annual variability in C fluxes and underestimating microbial activity throughout the cold season. The need to develop a comprehensive understanding of C fluxes over the entire year and at long temporal scales sets the basis of this study. This study aims to quantify the effects of permafrost thawing in permafrost C fluxes using a 12 years permafrost thaw experiment in northern Sweden. Our aims were to quantify the effect of permafrost thaw in both decomposition and primary production in active layer and newly thawed permafrost, and its implications for the C balance. Based on previous observations, we hypothesized that 1) soil decomposition rates were higher in manipulated thaw plots. However, 2) the observed increase in nutrients availability and the higher presence of vascular plants after thawing stimulate primary production, which compensates to some extent the increased C losses by respiration. To

  3. Spectral Dependent Degradation of the Solar Diffuser on Suomi-NPP VIIRS Due to Surface Roughness-Induced Rayleigh Scattering

    Directory of Open Access Journals (Sweden)

    Xi Shao

    2016-03-01

    Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.

  4. Strong geologic methane emissions from discontinuous terrestrial permafrost in the Mackenzie Delta, Canada.

    Science.gov (United States)

    Kohnert, Katrin; Serafimovich, Andrei; Metzger, Stefan; Hartmann, Jörg; Sachs, Torsten

    2017-07-19

    Arctic permafrost caps vast amounts of old, geologic methane (CH 4 ) in subsurface reservoirs. Thawing permafrost opens pathways for this CH 4 to migrate to the surface. However, the occurrence of geologic emissions and their contribution to the CH 4 budget in addition to recent, biogenic CH 4 is uncertain. Here we present a high-resolution (100 m × 100 m) regional (10,000 km²) CH 4 flux map of the Mackenzie Delta, Canada, based on airborne CH 4 flux data from July 2012 and 2013. We identify strong, likely geologic emissions solely where the permafrost is discontinuous. These peaks are 13 times larger than typical biogenic emissions. Whereas microbial CH 4 production largely depends on recent air and soil temperature, geologic CH 4 was produced over millions of years and can be released year-round provided open pathways exist. Therefore, even though they only occur on about 1% of the area, geologic hotspots contribute 17% to the annual CH 4 emission estimate of our study area. We suggest that this share may increase if ongoing permafrost thaw opens new pathways. We conclude that, due to permafrost thaw, hydrocarbon-rich areas, prevalent in the Arctic, may see increased emission of geologic CH 4 in the future, in addition to enhanced microbial CH 4 production.

  5. A promising tool for subsurface permafrost mapping-An application of airborne geophysics from the Yukon River Basin, Alaska

    Science.gov (United States)

    Abraham, Jared E.

    2011-01-01

    Permafrost is a predominant physical feature of the Earth's Arctic and Subarctic clines and a major consideration encompassing ecosystem structure to infrastructure engineering and placement. Perennially frozen ground is estimated to cover about 85 percent of the state of Alaska where northern reaches are underlain with continuous permafrost and parts of interior Alaska are underlain by areas of discontinuous and (or) sporadic permafrost (fig. 1). The region of Interior Alaska, where permafrost is scattered among unfrozen ground, is a complex mosaic of terrains and habitats. Such diversity creates arrays of lakes and surface-water and groundwater patterns that continental populations of migratory waterfowl and internationally significant fisheries have adapted to over time. A road or pipeline might pass over frozen and unfrozen ground, affecting the types of materials and engineering approaches needed to sustain the infrastructure.

  6. Permafrost in Marine Deposits at Ilulissat Airport in Greenland, Revisited

    DEFF Research Database (Denmark)

    Foged, Niels Nielsen; Ingeman-Nielsen, Thomas

    2008-01-01

    Ilulissat Airport was constructed in 1982 to 1984 after detailed geotechnical investigations as the construction site included up to 12 m thick basins of marine clay deposits. Despite soil temperatures of approx -3oC the soil appeared unfrozen from 4 to 5 m below ground surface due to a high...... residual salt content in the porewater. However, in the less saline top zone massive ice layers was found constituting up to 30 volume%. These formations representing a type example of saline permafrost caused the planned position of the runway to be shifted towards northwest and a removal of the layers...

  7. Mapping surficial geology and assessment of permafrost conditions under the Iqaluit airport, Nunavut, Canada

    Science.gov (United States)

    Mathon-Dufour, V.; Allard, M.; Leblanc, A.; L'Hérault, E.; Oldenborger, G. A.; Sladen, W. E.

    2012-12-01

    Formerly, characterization of permafrost conditions was minimal before the construction of infrastructures. It was assumed that the permafrost would forever remain a solid substrate. Before global warming, transportation infrastructures were not designed, especially in terms of materials and dimensions, to withstand without damage an increased input of heat in the soil. Iqaluit airport, the hub of the eastern Canadian Arctic, is currently affected by thawing permafrost. In fact, the runway, taxiways and apron are affected by differential settlements resulting from the presence of localized ice-rich soils. This study uses a GIS approach that makes up for the absence of appropriate characterization before the construction of the airport during WWII and in the 1950s. Mapping of surficial geology, hydrography and landforms indicative of the presence of ground ice (e.g. tundra polygons) was produced by interpreting aerial photographs dating back from the initial phases of construction (1948) and photographs taken at intervals since then, to the most recent high-resolution satellite images. Subsequent map analysis shows that the original terrain conditions prevailing before the construction of the airport have a significant impact on the current stability of the infrastructure. Data integration allowed us to summarize the main problems affecting the Iqaluit airport which are: 1) Differential settlements associated with pre-construction drainage network 2) Cracking due to thermal contraction, 3) Linear depressions associated with ice wedge degradation and 4) Sink holes. Most of the sectors affected by differential settlements and instabilities are perfectly coincident with the original streams and lakes network that has been filled to increase the size of the runway, taxiways and the apron. In addition, the runway is affected by intense frost cracking. Similarities with nearby natural terrain suggest that the network pattern of the cracks follows pre-existing ice wedges

  8. Future active layer dynamics and carbon dioxide production from thawing permafrost layers in Northeast Greenland

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Elberling, Bo; Jansson, P.E.

    2011-01-01

    from a moist permafrost soil in High-Arctic Greenland with observed heat production and carbon dioxide (CO2) release rates from decomposition of previously frozen organic matter. Observations show that the maximum thickness of the active layer at the end of the summer has increased 1 cm yr-1 since 1996......Thawing permafrost and the resulting mineralization of previously frozen organic carbon (C) is considered an important future feedback from terrestrial ecosystems to the atmosphere. Here, we use a dynamic process oriented permafrost model, the CoupModel, to link surface and subsurface temperatures......–105 cm as a result of a 2–6 °C warming. An additional increase in the maximum active layer thickness of a few centimetres may be expected due to heat production from decomposition of organic matter. Simulated future soil temperatures and water contents are subsequently used with measured basal soil...

  9. Viral impacts on microbial carbon cycling in thawing permafrost soils

    Science.gov (United States)

    Trubl, G. G.; Roux, S.; Bolduc, B.; Jang, H. B.; Emerson, J. B.; Solonenko, N.; Li, F.; Solden, L. M.; Vik, D. R.; Wrighton, K. C.; Saleska, S. R.; Sullivan, M. B.; Rich, V. I.

    2017-12-01

    species. Several identified hosts (e.g. Acidobacterium) are dominant community members that play major roles in C cycling through organic matter degradation. Together these findings show that permafrost viruses play a major role in the fate of soil C through infection of key hosts and metabolic reprogramming using specific C cycling AMGs.

  10. Seed banks in a degraded desert shrubland: Influence of soil surface condition and harvester ant activity on seed abundance

    Science.gov (United States)

    DeFalco, L.A.; Esque, T.C.; Kane, J.M.; Nicklas, M.B.

    2009-01-01

    We compared seed banks between two contrasting anthropogenic surface disturbances (compacted, trenched) and adjacent undisturbed controls to determine whether site condition influences viable seed densities of perennial and annual Mojave Desert species. Viable seeds of perennials were rare in undisturbed areas (3-4 seeds/m2) and declined to importance of litter as an indicator of site degradation and recovery potential in arid lands.

  11. Potential Environmental Factors Affecting Oil-Degrading Bacterial Populations in Deep and Surface Waters of the Northern Gulf of Mexico.

    Science.gov (United States)

    Liu, Jiqing; Bacosa, Hernando P; Liu, Zhanfei

    2016-01-01

    Understanding bacterial community dynamics as a result of an oil spill is important for predicting the fate of oil released to the environment and developing bioremediation strategies in the Gulf of Mexico. In this study, we aimed to elucidate the roles of temperature, water chemistry (nutrients), and initial bacterial community in selecting oil degraders through a series of incubation experiments. Surface (2 m) and bottom (1537 m) waters, collected near the Deepwater Horizon site, were amended with 200 ppm light Louisiana sweet crude oil and bacterial inoculums from surface or bottom water, and incubated at 4 or 24°C for 50 days. Bacterial community and residual oil were analyzed by pyrosequencing and gas chromatography-mass spectrometry (GC-MS), respectively. The results showed that temperature played a key role in selecting oil-degrading bacteria. Incubation at 4°C favored the development of Cycloclasticus, Pseudoalteromonas , Sulfitobacter , and Reinekea , while 24°C incubations enhanced Oleibacter, Thalassobius, Phaeobacter, and Roseobacter. Water chemistry and the initial community also had potential roles in the development of hydrocarbon-degrading bacterial communities. Pseudoalteromonas , Oleibacter , and Winogradskyella developed well in the nutrient-enriched bottom water, while Reinekea and Thalassobius were favored by low-nutrient surface water. We revealed that the combination of 4°C, crude oil and bottom inoculum was a key factor for the growth of Cycloclasticus , while the combination of surface inoculum and bottom water chemistry was important for the growth of Pseudoalteromonas . Moreover, regardless of the source of inoculum, bottom water at 24°C was a favorable condition for Oleibacter. Redundancy analysis further showed that temperature and initial community explained 57 and 19% of the variation observed, while oil and water chemistry contributed 14 and 10%, respectively. Overall, this study revealed the relative roles of temperature, water

  12. Permafrost in the Himalayas: specific characteristics, evolution vs. climate change and impacts on potential natural hazards

    Science.gov (United States)

    Fort, Monique

    2015-04-01

    Mountain environments are very sensitive to climate change, yet assessing the potential impacts of these changes is not easy because of the complexity and diversity of mountain systems. The Himalayan permafrost belt presents three main specificities: (1) it develops in a geodynamically active mountain, which means that the controlling factors are not only temperature but also seismo-tectonic activity; (2) due to the steepness of the southern flank of the Greater Himalaya and potential large scale rock failures, permafrost evidence manifests itself best in the inner valleys and on the northern, arid side of the Himalayas (elevations >4000m); (3) the east-west strike of the mountain range creates large spatial discontinuity in the "cold" belt, mostly related to precipitation nature and availability. Only limited studies have been carried to date, and there is no permanent "field laboratory", nor continuous records but a few local studies. Based on preliminary observations in the Nepal Himalayas (mostly in Mustang and Dolpo districts), and Indian Ladakh, we present the main features indicating the existence of permafrost (either continuous or discontinuous). Rock-glaciers are quite well represented, though their presence may be interpreted as a combined result from both ground ice and large rock collapse. The precise altitudinal zonation of permafrost belt (specifying potential permafrost, probable permafrost, observed permafrost belts) still requires careful investigations in selected areas. Several questions arise when considering the evolution of permafrost in a context of climate change, with its impacts on the development of potential natural hazards that may affect the mountain population. Firstly, permafrost degradation (ground ice melting) is a cause of mountain slope destabilization. When the steep catchments are developed in frost/water sensitive bedrock (shales and marls) and extend to high elevations (as observed in Mustang or Dolpo), it would supply more

  13. Thin, Conductive Permafrost Surrounding Lake Fryxell Indicates Salts From Past Lakes, McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Foley, N.; Tulaczyk, S. M.; Gooseff, M. N.; Myers, K. F.; Doran, P. T.; Auken, E.; Dugan, H. A.; Mikucki, J.; Virginia, R. A.

    2017-12-01

    In the McMurdo Dry Valleys (MDV), permafrost should be thick and liquid water rare. However, despite the well below zero mean annual temperature in this cryospheric desert, liquid water can be found in lakes, summer melt streams, subglacial outflow, and - recent work has shown - underneath anomalously thin permafrost. In part, this niche hydrosphere is maintained by the presence of salts, which depress the freezing point of water to perhaps as cold as -10° Celsius. We detected widespread salty water across the MDV in lakes and at depth using a helicopter-borne Time Domain Electromagnetic (TDEM) sensor. By using the presence of brines to mark the transition from frozen permafrost (near the surface) to unfrozen ground (at depth), we have created a map of permafrost thickness in Lower Taylor Valley (LTV), a large MDV with a complex history of glaciation and occupation by lakes. Our results show that permafrost is thinner ( 200m) than would be expected based on geothermal gradient measurements (up to 1000m), a result of the freezing point depression caused by salt and potentially enhanced by an unfinished transient freezing process. Near Lake Fryxell, a large, brackish lake in the center of LTV, permafrost is very thin (about 30-40m) and notably more electrically conductive than more distal permafrost. This thin ring of conductive permafrost surrounding the lake basin most likely reflects the high presence of salts in the subsurface, preventing complete freezing. These salts may be a remnant of the salty bottom waters of a historic larger lake (LGM glacially dammed Lake Washburn) or the remnant of salty basal water from a past advance of Taylor Glacier, which now sits many km up-valley but is known to contain brines which currently flow onto the surface and directly into the subsurface aquifer.

  14. Microbial communities of the deep unfrozen: Do microbes in taliks increase permafrost carbon vulnerability? (Invited)

    Science.gov (United States)

    Waldrop, M. P.; Blazewicz, S.; Jones, M.; Mcfarland, J. W.; Harden, J. W.; Euskirchen, E. S.; Turetsky, M.; Hultman, J.; Jansson, J.

    2013-12-01

    The vast frozen terrain of northern latitude ecosystems is typically thought of as being nearly biologically inert for the winter period. Yet deep within the frozen ground of northern latitude soils reside microbial communities that can remain active during the winter months. As we have shown previously, microbial communities may remain active in permafrost soils just below the freezing point of water. Though perhaps more importantly, microbial communities persist in unfrozen areas of water, soil, and sediment beneath water bodies the entire year. Microbial activity in taliks may have significant impacts on biogeochemical cycling in northern latitude ecosystems because their activity is not limited by the winter months. Here we present compositional and functional data, including long term incubation data, for microbial communities within permafrost landscapes, in permafrost and taliks, and the implications of these activities on permafrost carbon decomposition and the flux of CO2 and CH4. Our experiment was conducted at the Alaska Peatland Experiment (APEX) within the Bonanza Creek LTER in interior Alaska. Our site consists of a black spruce forest on permafrost that has degraded into thermokarst bogs at various times over the last five hundred years. We assume the parent substrate of the deep (1-1.5m) thermokarst peat was similar to the nearby forest soil and permafrost C before thaw. At this site, flux tower and autochamber data show that the thermokarst bog is a sink of CO2 , but a significant source of CH4. Yet this does not tell the whole story as these data do not fully capture microbial activity within the deep unfrozen talik layer. There is published evidence that within thermokarst bogs, relatively rapid decomposition of old forest floor material may be occurring. There are several possible mechanisms for this pattern; one possible mechanism for accelerated decomposition is the overwintering activities of microbial communities in taliks of thermokarst

  15. Organic carbon biolabilty increases with depth in a yedoma permafrost profile in Interior Alaska

    Science.gov (United States)

    Heslop, J. K.; Walter Anthony, K. M.; Spencer, R.; Winkel, M.; Zhang, M.; Liebner, S.; Podgorski, D. C.; Zito, P.; Kholodov, A. L.

    2017-12-01

    Permafrost organic carbon (OC) biolability is known to be controlled by both the OC molecular composition and redox state and the microbial community structure and its response to permafrost thaw. However, due to their complexity, both these mechanisms remain poorly understood. A substantial portion ( 16%) of global permafrost OC is stored in particularly deep, ice-rich permafrost deposits known as yedoma. We anaerobically incubated sediment from four depths in a 12-m yedoma profile in Interior Alaska with three treatments: control without amendment, inoculated with sediment from an adjacent thermokarst lake, and inoculated with sterilized lake sediment. We quantified CO2 and CH4 as end products of C mineralization, used qPCR to characterize the initial methanogenic communities, and used FT-ICR-MS to characterize the molecular composition of water-extractable organic matter at the beginning and end of the 154-d incubation. Proportions of aliphatics and peptides increased with depth in the permafrost profile, which would be consistent with long-term accumulation of anaerobic fermentation end products in yedoma-type permafrost. Moreover, these compounds positively correlated with anaerobic CO2 and CH4 production and their degradation rates corresponded to high proportions (53.3 ±41.9%) of OC mineralization, suggesting increasing proportions of these compounds with depth correspond to increasing OC quality and increased C mineralization per unit OC. Methanogenic communities were below detection limits in all controls. Following exposure to modern lake sediment microbial communities with detectable methanogens, we observed increases in anaerobic CO2 (65.1% ±75.2%) and CH4 (1,197% ±914%) production. The treatments with sterilized lake sediment did not contain detectable methanogens, and had increased anaerobic CO2 (52.6% ±69.2%) production but decreased CH4 (-74.1% ±33.8%) production. These preliminary results suggest anaerobic CH4 production is limited by ancient

  16. Air duct systems for roadway stabilization over permafrost areas

    Science.gov (United States)

    1984-03-01

    In the discontinuous permafrost regions of Alaska it is not always possible to route roads over non-permafrost ground. For areas like these, highway engineers face a tremendous design challenge in attempting to provide a stable roadway base. Several ...

  17. Circumpolar Active-Layer Permafrost System (CAPS), Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Circumpolar Active-Layer Permafrost System (CAPS) contains over 100 data sets pertaining to permafrost and frozen ground topics. It also contains detailed...

  18. Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes

    DEFF Research Database (Denmark)

    Hultman, Jenni; Waldrop, Mark P.; Mackelprang, Rachel

    2015-01-01

    Over 20% of Earth's terrestrial surface is underlain by permafrost with vast stores of carbon that, once thawed, may represent the largest future transfer of carbon from the biosphere to the atmosphere(1). This process is largely dependent on microbial responses, but we know little about microbia...

  19. Thermal conditions of rock slopes below unstable infrastructure in Alpine permafrost area: the cases of the Cosmiques hut and the Grands Montets cable-car station (Mont Blanc massif)

    Science.gov (United States)

    Duvillard, Pierre-Allain; Magnin, Florence; Mörtl, Christian; Ravanel, Ludovic; Deline, Philip

    2017-04-01

    Thermal state of steep permafrost-affected rock faces is crucial to assess the safety and reliability of mountain infrastructure as current permafrost degradation affects the rock slope stability. In the Mont-Blanc massif, 23 infrastructures are built on such a rock face with 13 of them that are characterized by a high risk of destabilization (Duvillard et al., 2015), including the upper station of the Grands Montets cable car (3325 m a.s.l.) as well as the Cosmiques hut (3613 m a.s.l.) on which we will focus. These two buildings have already been affected by different geomorphological processes. A rockfall event (600 m3) occurred for example on the SE face on the Arête inférieure des Cosmiques on the 21st of August 1998 (Ravanel et al., 2013) and the Grands Montets case shows a slow subsidence of the stairway over the last decade. In order to better assess the role of the permafrost in these processes and to gain insight on possible future geomorphic activity, we characterized the current permafrost conditions and simulated its changes up to the end of the 21st century using two complementary approaches: (i) the result of ERT (Electrical Resistivity Tomography) surveys carried out in October 2016 on the northern and southern faces right below the Cosmiques hut (at the level of the foundations) and at the Aiguilles des Grands Montets; (ii) the modeling of mean annual rock surface temperature for 2016 and at the end of the 21st century (Magnin et al., in rev.). Duvillard P.-A., Ravanel L., Deline P. (2015). Risk assessment of infrastructure destabilisation due to global warming in the high French Alps. Journal of Alpine Research, 103 (2). Magnin F., Josnin J.-Y., Ravanel L., Pergaud J., Pohl B., Deline P. (in rev.). Modelling rock wall permafrost degradation in the Mont Blanc massif from the LIA to the end of the 21st century. The Cryosphere Discuss., doi:10.5194/tc-2016-132. Ravanel L., Deline P., Lambiel C. and Vincent C. (2013). Instability of a high alpine

  20. Assessment of LiDAR and Spectral Techniques for High-Resolution Mapping of Sporadic Permafrost on the Yukon-Kuskokwim Delta, Alaska

    Directory of Open Access Journals (Sweden)

    Matthew A. Whitley

    2018-02-01

    Full Text Available Western Alaska’s Yukon-Kuskokwim Delta (YKD spans nearly 67,200 km2 and is among the largest and most productive coastal wetland ecosystems in the pan-Arctic. Permafrost currently forms extensive elevated plateaus on abandoned floodplain deposits of the outer delta, but is vulnerable to disturbance from rising air temperatures, inland storm surges, and salt-kill of vegetation. As pan-Arctic air and ground temperatures rise, accurate baseline maps of permafrost extent are critical for a variety of applications including long-term monitoring, understanding the scale and pace of permafrost degradation processes, and estimating resultant greenhouse gas dynamics. This study assesses novel, high-resolution techniques to map permafrost distribution using LiDAR and IKONOS imagery, in tandem with field-based parameterization and validation. With LiDAR, use of a simple elevation threshold provided a permafrost map with 94.9% overall accuracy; this approach was possible due to the extremely flat coastal plain of the YKD. The addition of high spatial-resolution IKONOS satellite data yielded similar results, but did not increase model performance. The methods and the results of this study enhance high-resolution permafrost mapping efforts in tundra regions in general and deltaic landscapes in particular, and provide a baseline for remote monitoring of permafrost distribution on the YKD.

  1. Coupling of snow and permafrost processes using the Basic Modeling Interface (BMI)

    Science.gov (United States)

    Wang, K.; Overeem, I.; Jafarov, E. E.; Piper, M.; Stewart, S.; Clow, G. D.; Schaefer, K. M.

    2017-12-01

    We developed a permafrost modeling tool based by implementing the Kudryavtsev empirical permafrost active layer depth model (the so-called "Ku" component). The model is specifically set up to have a basic model interface (BMI), which enhances the potential coupling to other earth surface processes model components. This model is accessible through the Web Modeling Tool in Community Surface Dynamics Modeling System (CSDMS). The Kudryavtsev model has been applied for entire Alaska to model permafrost distribution at high spatial resolution and model predictions have been verified by Circumpolar Active Layer Monitoring (CALM) in-situ observations. The Ku component uses monthly meteorological forcing, including air temperature, snow depth, and snow density, and predicts active layer thickness (ALT) and temperature on the top of permafrost (TTOP), which are important factors in snow-hydrological processes. BMI provides an easy approach to couple the models with each other. Here, we provide a case of coupling the Ku component to snow process components, including the Snow-Degree-Day (SDD) method and Snow-Energy-Balance (SEB) method, which are existing components in the hydrological model TOPOFLOW. The work flow is (1) get variables from meteorology component, set the values to snow process component, and advance the snow process component, (2) get variables from meteorology and snow component, provide these to the Ku component and advance, (3) get variables from snow process component, set the values to meteorology component, and advance the meteorology component. The next phase is to couple the permafrost component with fully BMI-compliant TOPOFLOW hydrological model, which could provide a useful tool to investigate the permafrost hydrological effect.

  2. Simulation of Streamflow in a Discontinuous Permafrost Environment Using a Modified First-order, Nonlinear Rainfall-runoff Model

    Science.gov (United States)

    Bolton, W. R.; Hinzman, L. D.

    2009-12-01

    The sub-arctic environment can be characterized by being located in the zone of discontinuous permafrost. Although the distribution of permafrost in this region is specific, it dominates the response of many of the hydrologic processes including stream flow, soil moisture dynamics, and water storage processes. In areas underlain by permafrost, ice-rich conditions at the permafrost table inhibit surface water percolation to the deep subsurface soils, resulting in an increased runoff generation generation during precipitation events, decreased baseflow between precipitation events, and relatively wetter soils compared to permafrost-free areas. Over the course of a summer season, the thawing of the active layer (the thin soil layer about the permafrost that seasonally freezes and thaws) increases the potential water holding capacity of the soil, resulting in a decreasing surface water contribution during precipitation events and a steadily increasing baseflow contribution between precipitation events. Simulation of stream flow in this region is challenging due to the rapidly changing thermal (permafrost versus non-permafrost, active layer development) and hydraulic (hydraulic conductivity and soil storage capacity) conditions in both time and space (x, y, and z-dimensions). Many of the factors that have a control on both permafrost distribution and the thawing/freezing of active layer (such as soil material, soil moisture, and ice content) are not easily quantified at scales beyond the point measurement. In this study, these issues are addressed through streamflow analysis - the only hydrologic process that is easily measured at the basin scale. Following the general procedure outlined in Kirchner (2008), a simple rainfall-runoff model was applied to three small head-water basins of varying permafrost coverage. A simple, first-order, non-linear differential equation that describes the storage-discharge relationship were derived from three years of stream flow data

  3. Developing a mechanistically consistent picture of permafrost influence on hydrologic response (Invited)

    Science.gov (United States)

    Lyon, S. W.

    2013-12-01

    In regions experiencing permafrost thaw, catchment structure is a dynamic factor mediating hydrologic response. Predicting how this mediation will manifest is difficult since there are myriad potential hydrologic consequences from thawing permafrost such as changes to the connectivity of the aquifer system and the amount of water available for groundwater storage. For example, despite similar climate evolution and permafrost degradation over the past century, contrasting trends can be seen in the magnitude and timing of flood peaks and the mean summer discharge regionally across northern Sweden. Complementing hydrological change information with observations and detailed modeling provides a more mechanistically consistent picture of the hydrologic response impacts due to thawing permafrost. This is particularly relevant with regards to the timing of water flows that control the cycling of Carbon and other biogeochemicals within subarctic environments. As such, there is a clear added value in considering coupled process-functional changes in complement to the absolute hydrologic changes that integrate and, thus, may mask subsystem shifts in hydrologic responses (amount and timing).

  4. Simulation of pollutant transport in mobile water-flow channels in permafrost environment

    Directory of Open Access Journals (Sweden)

    E. I. Debolskaya

    2013-01-01

    Full Text Available A common problem for the Arctic region is pollution by persistent organic compounds and other substances that have accumulated over the years in these areas. With temperature increasing, these substances can get out of the snow, ice, permafrost in the human environment. With climate warming and permafrost degradation the risk of toxic substances from the burial sites of chemical and radioactive waste increases. The work is devoted to research the pollution propagation in the rivers flowing in the permafrost taking into account the possible deformations of the channels caused by the melting of the permafrost with increasing temperature of the river flow water. We also consider the distribution of pollutants released during erosion of the coastal slopes, caused thermal erosion. Numerical experiments confirmed the quantitative assessment obtained from the field observations of the erosion rate increases with increasing temperature. Study the impact of thermal and mechanical erosion of the distribution of impurities led to the conclusion that as a result of the formation of taliks uniform flow conditions are violated, resulting in a non-stationary distribution of impurities. The increase in the volume of the test section of the river due to the appearance of cavities in the coastal slope leads to an increase in impurity concentration. Analysis of the results of modeling the spread of contamination during thawing sources in the frozen shores, demonstrated the relationship in the process of distribution of impurities from the position of the source and allowed to give a preliminary quantitative assessment.

  5. Potential remobilization of belowground permafrost carbon under future global warming

    Science.gov (United States)

    P. Kuhry; E. Dorrepaal; G. Hugelius; E.A.G. Schuur; C. Tarnocai

    2010-01-01

    Research on permafrost carbon has dramatically increased in the past few years. A new estimate of 1672 Pg C of belowground organic carbon in the northern circumpolar permafrost region more than doubles the previous value and highlights the potential role of permafrost carbon in the Earth System. Uncertainties in this new estimate remain due to relatively few available...

  6. Geophysical Investigations of Saline Permafrost at Ilulissat, Greenland

    DEFF Research Database (Denmark)

    Ingeman-Nielsen, Thomas; Foged, Niels Nielsen; Butzbach, Rune

    2008-01-01

    The technical properties and general state of permafrost in Greenland is not well documented. A new coordinated investigation has been initiated, for ground temperature measurements and permafrost mapping in Greenlandic towns in sporadic, discontinuous and continuous permafrost zones. We present...... properties, and the sediments have a limited heat capacity available, should the temperature conditions change....

  7. Biomarker and carbon isotope constraints (δ{sup 13}C, Δ{sup 14}C) on sources and cycling of particulate organic matter discharged by large Siberian rivers draining permafrost areas

    Energy Technology Data Exchange (ETDEWEB)

    Winterfeld, Maria

    2014-08-15

    consistent with inputs of OM from non-woody angiosperm sources mixed with organic matter derived from woody gymnosperm sources. A simple linear mixing model based on the lignin phenol distributions indicates organic matter in TSM samples from the delta and Buor Khaya Bay surface sediments contain comparable contributions from gymnosperm sources, which are primarily from the taiga forests south of the delta, and angiosperm material typical for tundra vegetation. Considering the small area covered by tundra (∝12% of total catchment), the input of tundra-derived OM input is substantial and likely to increase in a warming Arctic. Radiocarbon compositions (Δ{sup 14}C) of bulk OM in Lena River TSM samples varied from -55 to -391 permille, translating into {sup 14}C ages of 395 to 3920 years BP. Using δ{sup 13}C compositions to estimate the fraction of phytoplankton-derived OM and assuming that this material has a modern {sup 14}C signature, we inferred the Δ{sup 14}C compositions of terrigenous OM in TSM exported by the Lena River to range between -190 and -700 permille. Such variability in the ages of terrigenous OM (i.e. 1640 to 9720 {sup 14}C years BP) reflects the heterogeneous composition and residence time of OM in the Lena River catchment soils (Holocene to Pleistocene ages). Lignin phenol and Δ{sup 14}C compositions of surface sediments from the adjacent Buor Khaya Bay suggest that terrestrial OM deposited there is older and more degraded than materials present in river particles and catchment soils. Stronger diagenetic alteration in Lena Delta TSM and marine sediments relative to soils may reflect degradation of more labile components during permafrost thawing and transport. Despite the high natural heterogeneity in catchment soils, the lignin biomarker compositions and radiocarbon ages of terrestrial OM exported by the Lena River reflect catchment characteristics such as vegetation and soil type. Climate warming related changes in the Lena River catchment may be

  8. Effect of denture-coating composite on Candida albicans biofilm and surface degradation after disinfection protocol.

    Science.gov (United States)

    Silva, Matheus Jacobina; de Oliveira, Denise G; Marcillo, Oscar O; Neppelenbroek, Karin H; Lara, Vanessa S; Porto, Vinícius C

    2016-04-01

    Denture stomatitis is the most common pathology affecting denture wearers and its main cause is colonisation of dentures with Candida albicans. This study investigated the effectiveness of two commercial composite surface sealants (Biscover(®) LV and Surface Coat(®)) to reduce C. albicans biofilm colonisation on denture resin, as well as their surface integrity after disinfection cycles with 1% sodium hypochlorite solution. Heat-cured acrylic resin specimens were manufactured (10 mm × 10 mm × 1 mm). The specimen surfaces were mechanically polished to simulate rough or smooth denture surfaces. Four surface-treatment groups were tested: smooth surfaces [0.3 μm of mean roughness (Ra)]; rough surfaces (3 μm of Ra); rough surfaces treated with Biscover(®) LV; and rough surfaces treated with Surface Coat(®). Specimens of each group were randomly divided to undergo immersion in distilled water or 1% sodium hypochlorite for 30 or 90 cycles each. Specimens of all groups in each immersion solution were tested using a crystal violet (CV) staining assay for biofilm quantification and by scanning electron microscopy for visual analyses of surface integrity and biofilm structure. CV assay data were analysed using one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison test (P surface integrity of Biscover(®) LV-treated surfaces were similar to those of smooth surfaces, whereas Surface Coat(®) -treated surfaces presented a similar performance to rough surfaces in all solutions and cycles. These results suggest the possibility of clinical use of Biscover(®) LV for denture coating on surfaces in which mechanical polish is not indicated, such as the fitting surface. © 2016 FDI World Dental Federation.

  9. Surface binding sites in amylase have distinct roles in recognition of starch structure motifs and degradation

    DEFF Research Database (Denmark)

    Cockburn, Darrell; Nielsen, Morten M.; Christiansen, Camilla

    2015-01-01

    degrading enzymes and critically important for their function. The affinity towards a variety of starch granules as well as soluble poly- and oligosaccharides of barley alpha-amylase 1 (AMY1) wild-type and mutants of two SBSs (SBS1 and SBS2) was investigated using Langmuir binding analysis, confocal laser...

  10. Tailoring degradation of AZ31 alloy by surface pre-treatment and electrospun PCL fibrous coating.

    Science.gov (United States)

    Hanas, T; Sampath Kumar, T S; Perumal, Govindaraj; Doble, Mukesh

    2016-08-01

    AZ31 magnesium alloy was coated with polycaprolactone (PCL) nano-fibrous layer using electrospinning technique so as to control degradation in physiological environment. Before coating, the alloy was treated with HNO3 to have good adhesion between the coating and substrate. To elucidate the role of pre-treatment and coating, samples only with PCL coating as well as HNO3 treatment only were prepared for comparison. Best coating adhesion of 4B grade by ASTM D3359-09 tape test was observed for pre-treated samples. The effect of coating on in vitro degradation and biomineralization was studied using supersaturated simulated body fluid (SBF 5×). The weight loss and corrosion results obtained by immersion test showed that the combination of HNO3 pre-treatment and PCL coating is very effective in controlling the degradation rate and improving bioactivity. Cytotoxicity studies using L6 cells showed that PCL coated sample has better cell adhesion and proliferation compared to uncoated samples. Nano-fibrous PCL coating combined with prior acid treatment seems to be a promising method to tailor degradation rate with enhanced bioactivity of Mg alloys. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Tailoring degradation of AZ31 alloy by surface pre-treatment and electrospun PCL fibrous coating

    Energy Technology Data Exchange (ETDEWEB)

    Hanas, T. [Medical Materials Laboratory, Indian Institute of Technology Madras, Chennai 600036 (India); School of Nano Science and Technology, National Institute of Technology Calicut, Calicut, Kerala 673601 (India); Sampath Kumar, T.S., E-mail: tssk@iitm.ac.in [Medical Materials Laboratory, Indian Institute of Technology Madras, Chennai 600036 (India); Perumal, Govindaraj; Doble, Mukesh [Department of Biotechnology - Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036 (India)

    2016-08-01

    AZ31 magnesium alloy was coated with polycaprolactone (PCL) nano-fibrous layer using electrospinning technique so as to control degradation in physiological environment. Before coating, the alloy was treated with HNO{sub 3} to have good adhesion between the coating and substrate. To elucidate the role of pre-treatment and coating, samples only with PCL coating as well as HNO{sub 3} treatment only were prepared for comparison. Best coating adhesion of 4B grade by ASTM D3359–09 tape test was observed for pre-treated samples. The effect of coating on in vitro degradation and biomineralization was studied using supersaturated simulated body fluid (SBF 5 ×). The weight loss and corrosion results obtained by immersion test showed that the combination of HNO{sub 3} pre-treatment and PCL coating is very effective in controlling the degradation rate and improving bioactivity. Cytotoxicity studies using L6 cells showed that PCL coated sample has better cell adhesion and proliferation compared to uncoated samples. Nano-fibrous PCL coating combined with prior acid treatment seems to be a promising method to tailor degradation rate with enhanced bioactivity of Mg alloys. - Highlights: • PCL electrospun coating on HNO{sub 3} pre-treated AZ31 alloy controls biodegradation. • Acid pre-treatment stabilizes the substrate - coating interface. • Electrospun porous coating improves biomineralization. • Coating similar to extracellular matrix enhances cell adhesion.

  12. Frozen Stiff: Cartographic Design and Permafrost Mapping

    Science.gov (United States)

    Nelson, F. E.; Li, J.; Nyland, K. E.

    2016-12-01

    Maps are the primary vehicle used to communicate geographical relationships. Ironically, interest in the formal practice of cartography, the art and science of geographic visualization, has fallen significantly during a period when the sophistication and availability of GIS software has increased dramatically. Although the number of geographically oriented permafrost studies has increased significantly in recent years, little discussion about competing visualization strategies, map accuracy, and the psychophysical impact of cartographic design is evident in geocryological literature. Failure to use the full potential of the tools and techniques that contemporary cartographic and spatial-analytic theory makes possible affects our ability to effectively and accurately communicate the impacts and hazards associated with thawing permafrost, particularly in the context of global climate change. This presentation examines recent permafrost studies involving primarily small-scale (large area) mapping, and suggests cartographic strategies for rectifying existing problems.

  13. Biodegradation of bispyribac sodium by a novel bacterial consortium BDAM: Optimization of degradation conditions using response surface methodology.

    Science.gov (United States)

    Ahmad, Fiaz; Anwar, Samina; Firdous, Sadiqa; Da-Chuan, Yin; Iqbal, Samina

    2018-05-05

    Bispyribac sodium (BS), is a selective, systemic and post emergent herbicide used to eradicate grasses and broad leaf weeds. Extensive use of this herbicide has engendered serious environmental concerns. Hence it is important to develop strategies for bioremediation of BS in a cost effective and environment friendly way. In this study a bacterial consortium named BDAM, comprising three novel isolates Achromobacter xylosoxidans (BD1), Achromobacter pulmonis (BA2), and Ochrobactrum intermedium (BM2), was developed by virtue of its potential for degradation of BS. Different culture conditions (temperature, pH and inoculum size) were optimized for degradation of BS by the consortium BDAM and the mutual interactions of these parameters were analysed using a 2 3 full factorial central composite design (CCD) based on Response Surface Methodology (RSM). The optimal values for temperature, pH and inoculum size were found to be 40 °C, 8 and 0.4 g/L respectively to achieve maximum degradation of BS (85.6%). Moreover, the interactive effects of these parameters were investigated using three dimensional surface plots in terms of maximum fitness function. Importantly, it was concluded that the newly developed consortium is a potential candidate for biodegradation of BS in a safe, cost-effective and environmentally friendly manner. Copyright © 2017. Published by Elsevier B.V.

  14. Permafrost degradation stimulates carbon loss from experimentally warmed tundra

    Science.gov (United States)

    S.M. Natali; E.A.G. Schuur; E. Webb; C.E. Hicks Pries; K.G. Crummer

    2014-01-01

    A large pool of organic carbon (C) has been accumulating in the Arctic for thousands of years because cold and waterlogged conditions have protected soil organic material from microbial decomposition. As the climate warms this vast and frozen C pool is at risk of being thawed, decomposed, and released to the atmosphere as greenhouse gasses. At the same time, some C...

  15. Climate change and the permafrost carbon feedback

    Science.gov (United States)

    Schuur, E.A.G.; McGuire, A. David; Schädel, C.; Grosse, G.; Harden, J.W.; Hayes, D.J.; Hugelius, G.; Koven, C.D.; Kuhry, P.; Lawrence, D.M.; Natali, Susan M.; Olefeldt, David; Romanovsky, V.E.; Schaefer, K.; Turetsky, M.R.; Treat, C.C.; Vonk, J.E.

    2015-01-01

    Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emission from these regions and their impact on climate change remain uncertain. Here we find that current evidence suggests a gradual and prolonged release of greenhouse gas emissions in a warming climate and present a research strategy with which to target poorly understood aspects of permafrost carbon dynamics.

  16. Climate change and the permafrost carbon feedback.

    Science.gov (United States)

    Schuur, E A G; McGuire, A D; Schädel, C; Grosse, G; Harden, J W; Hayes, D J; Hugelius, G; Koven, C D; Kuhry, P; Lawrence, D M; Natali, S M; Olefeldt, D; Romanovsky, V E; Schaefer, K; Turetsky, M R; Treat, C C; Vonk, J E

    2015-04-09

    Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emission from these regions and their impact on climate change remain uncertain. Here we find that current evidence suggests a gradual and prolonged release of greenhouse gas emissions in a warming climate and present a research strategy with which to target poorly understood aspects of permafrost carbon dynamics.

  17. Linear disturbances on discontinuous permafrost: implications for thaw-induced changes to land cover and drainage patterns

    International Nuclear Information System (INIS)

    Williams, Tyler J; Quinton, William L; Baltzer, Jennifer L

    2013-01-01

    Within the zone of discontinuous permafrost, linear disturbances such as winter roads and seismic lines severely alter the hydrology, ecology, and ground thermal regime. Continued resource exploration in this environment has created a need to better understand the processes causing permafrost thaw and concomitant changes to the terrain and ground cover, in order to efficiently reduce the environmental impact of future exploration through the development of best management practices. In a peatland 50 km south of Fort Simpson, NWT, permafrost thaw and the resulting ground surface subsidence have produced water-logged linear disturbances that appear not to be regenerating permafrost, and in many cases have altered the land cover type to resemble that of a wetland bog or fen. Subsidence alters the hydrology of plateaus, developing a fill and spill drainage pattern that allows some disturbances to be hydrologically connected with adjacent wetlands via surface flow paths during periods of high water availability. The degree of initial disturbance is an important control on the extent of permafrost thaw and thus the overall potential recovery of the linear disturbance. Low impact techniques that minimize ground surface disturbance and maintain original surface topography by eliminating windrows are needed to minimize the impact of these linear disturbances. (letter)

  18. In-situ degradation of sulphur mustard and its simulants on the surface of impregnated carbon systems

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Abha [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India); Saxena, Amit [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India); Singh, Beer [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India)]. E-mail: beerbs5@rediffmail.com; Sharma, Mamta [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India); Suryanarayana, Malladi Venkata Satya [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India); Semwal, Rajendra Prasad [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India); Ganeshan, Kumaran [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India); Sekhar, Krishnamurthy [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India)

    2006-05-20

    Bis-2-chloroethyl sulphide (sulphur mustard or HD) is an extremely toxic and persistent chemical warfare agent. For in situ degradation of HD and its analogues (simulants), i.e., dibutyl sulphide (DBS) and ethyl 2-hydroxyethyl sulphide (HEES), different carbon systems such as 11-molybdo-1-vanadophosphoric acid impregnated carbon (V{sub 1}/C), ruthenium chloride impregnated carbon (Ru/C) and combination of these two (V{sub 1}/Ru/C) were prepared. These carbons were characterized for cumulative micropore volume and surface area by N{sub 2} BET. The kinetics of the in situ degradation of HD and its simulants were studied and found to be following the first order kinetics. Kinetic rate constants and t {sub 1/2} values were determined. Products were characterized using NMR, IR and GC-MS. Reaction products were found to be sulphoxide and sulphone. The combined system, i.e., 11-molybdo-1-vanadophosphoric acid plus ruthenium chloride (V{sub 1}/Ru/C) was found to be best for in-situ degradation of HD and its simulants. In-situ degradation by polyoxometalate based system was found to be stoichiometry based while Ru/C oxidized HD in presence of chemisorbed oxygen. In combined system of V{sub 1}/Ru/C ruthenium worked as a catalyst and polyoxometalate acted as a source of oxygen. Effect of moisture was also studied in combined system. Rate of degradation of HD was found to be increasing with increased percentage of moisture content.

  19. A case study of high Arctic anthropogenic disturbance to polar desert permafrost and ecosystems

    Science.gov (United States)

    Becker, M. S.; Pollard, W. H.

    2013-12-01

    One of the indirect impacts of climate change on Arctic ecosystems is the expected increase of industrial development in high latitudes. The scale of terrestrial impacts cannot be known ahead of time, particularly due to a lack of long-term impact studies in this region. With one of the slowest community recovery rates of any ecosystem, the high Artic biome will be under a considerable threat that is exacerbated by a high susceptibility to change in the permafrost thermal balance. One such area that provides a suitable location for study is an old airstrip near Eureka, Ellesmere Island, Nunavut (80.0175°N, 85.7340°W). While primarily used as an ice-runway for winter transport, the airstrip endured a yearly summer removal of vegetation that continued from 1947 until its abandonment in 1951. Since then, significant vegetative and geomorphic differences between disturbed and undisturbed areas have been noted in the literature throughout the decades (Bruggemann, 1953; Beschel, 1963; Couture and Pollard, 2007), but no system wide assessment of both the ecosystem and near-surface permafrost has been conducted. Key to our study is that the greatest apparent geomorphic and vegetative changes have occurred and persisted in areas where underlying ice-wedges have been disturbed. This suggests that the colonizing communities rapidly filled new available thermokarst niches and have produced an alternative ice-wedge stable state than the surrounding polar desert. We hypothesize that disturbed areas will currently have greater depths of thaw (deeper active layers) and degraded ice-wedges, with decreased vegetation diversity but higher abundance due to a changed hydrological balance. To test this a comprehensive set of near-surface active layer and ecosystem measurements were conducted. Permafrost dynamics were characterized using probing and high-frequency Ground Penetrating Radar (500 MHz) to map the near-surface details of ice-wedges and active layer. Vegetation was measured

  20. Degradation of the electrospun silica nanofiber in a biological medium for primary hippocampal neuron – effect of surface modification

    Directory of Open Access Journals (Sweden)

    Feng ZV

    2016-02-01

    Full Text Available Z Vivian Feng,1,* Wen Shuo Chen,2,* Khomson Keratithamkul,1 Michael Stoick,1 Brittany Kapala,3 Eryn Johnson,3 An-Chi Huang,2 Ting Yu Chin,4 Yui Whei Chen-Yang,2 Mong-Lin Yang3 1Chemistry Department, Augsburg College, Minneapolis, MN, USA; 2Department of Chemistry, Center for Nanotechnology, Center for Biomedical Technology, Chung Yuan Christian University, Chung Li, Taiwan, Republic of China; 3Department of Science, Concordia University Saint Paul, Saint Paul, MN, USA; 4Department of Bioscience Technology, Chung Yuan Christian University, Chung Li, Taiwan, Republic of China *These authors contributed equally to this work Abstract: In this work, silica nanofibers (SNFs were prepared by an electrospinning method and modified with poly-D-lysine (PDL or (3-aminopropyl trimethoxysilane (APTS making biocompatible and degradable substrates for neuronal growth. The as-prepared SNF, modified SNF-PDL, and SNF-APTS were evaluated using scanning electron microscopy, nitrogen adsorption/desorption isotherms, contact angle measurements, and inductively coupled plasma atomic emission spectroscopy. Herein, the scanning electron microscopic images revealed that dissolution occurred in a corrosion-like manner by enlarging porous structures, which led to loss of structural integrity. In addition, covalently modified SNF-APTS with more hydrophobic surfaces and smaller surface areas resulted in significantly slower dissolution compared to SNF and physically modified SNF-PDL, revealing that different surface modifications can be used to tune the dissolution rate. Growth of primary hippocampal neuron on all substrates led to a slower dissolution rate. The three-dimensional SNF with larger surface area and higher surface density of the amino group promoted better cell attachment and resulted in an increased neurite density. This is the first known work addressing the degradability of SNF substrate in physiological conditions with neuron growth in vitro, suggesting a

  1. Canadian Geothermal Data Collection: Deep permafrost temperatures and thickness of permafrost, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — Precision temperature measurements have been made in some 150 deep wells and holes drilled in the course of natural resource exploration in the permafrost regions of...

  2. Preparing near-surface heavy oil for extraction using microbial degradation

    Energy Technology Data Exchange (ETDEWEB)

    Busche, Frederick D.; Rollins, John B.; Noyes, Harold J.; Bush, James G.

    2017-05-30

    In one embodiment, the invention provides a system including at least one computing device for enhancing the recovery of heavy oil in an underground, near-surface crude oil extraction environment by performing a method comprising sampling and identifying microbial species (bacteria and/or fungi) that reside in the underground, near-surface crude oil extraction environment; collecting rock and fluid property data from the underground, near-surface crude oil extraction environment; collecting nutrient data from the underground, near-surface crude oil extraction environment; identifying a preferred microbial species from the underground, near-surface crude oil extraction environment that can transform the heavy oil into a lighter oil; identifying a nutrient from the underground, near-surface crude oil extraction environment that promotes a proliferation of the preferred microbial species; and introducing the nutrient into the underground, near-surface crude oil extraction environment.

  3. Surface Soil Preparetion for Leguminous Plants Growing in Degraded Areas by Mining Located in Amazon Forest-Brazil

    Science.gov (United States)

    Irio Ribeiro, Admilson; Hashimoto Fengler, Felipe; Araújo de Medeiros, Gerson; Márcia Longo, Regina; Frederici de Mello, Giovanna; José de Melo, Wanderley

    2015-04-01

    The revegetation of areas degraded by mining usually requires adequate mobilization of surface soil for the development of the species to be implemented. Unlike the traditional tillage, which has periodicity, the mobilization of degraded areas for revegetation can only occur at the beginning of the recovery stage. In this sense, the process of revegetation has as purpose the establishment of local native vegetation with least possible use of inputs and superficial tillage in order to catalyze the process of natural ecological succession, promoting the reintegration of areas and minimizing the negative impacts of mining activities in environmental. In this context, this work describes part of a study of land reclamation by tin exploitation in the Amazon ecosystem in the National Forest Jamari- Rondonia Brazil. So, studied the influence of surface soil mobilization in pit mine areas and tailings a view to the implementation of legumes. The results show that the surface has areas of mobilizing a significant effect on the growth of leguminous plants, areas for both mining and to tailings and pit mine areas.

  4. Limited contribution of permafrost carbon to methane release from thawing peatlands

    Science.gov (United States)

    Cooper, Mark D. A.; Estop-Aragonés, Cristian; Fisher, James P.; Thierry, Aaron; Garnett, Mark H.; Charman, Dan J.; Murton, Julian B.; Phoenix, Gareth K.; Treharne, Rachael; Kokelj, Steve V.; Wolfe, Stephen A.; Lewkowicz, Antoni G.; Williams, Mathew; Hartley, Iain P.

    2017-07-01

    Models predict that thaw of permafrost soils at northern high latitudes will release tens of billions of tonnes of carbon (C) to the atmosphere by 2100 (refs ,,). The effect on the Earth’s climate depends strongly on the proportion of this C that is released as the more powerful greenhouse gas methane (CH4), rather than carbon dioxide (CO2) (refs ,); even if CH4 emissions represent just 2% of the C release, they would contribute approximately one-quarter of the climate forcing. In northern peatlands, thaw of ice-rich permafrost causes surface subsidence (thermokarst) and water-logging, exposing substantial stores (tens of kilograms of C per square meter, ref. ) of previously frozen organic matter to anaerobic conditions, and generating ideal conditions for permafrost-derived CH4 release. Here we show that, contrary to expectations, although substantial CH4 fluxes (>20 g CH4 m-2 yr-1) were recorded from thawing peatlands in northern Canada, only a small amount was derived from previously frozen C (changes in surface wetness and wetland area, rather than the anaerobic decomposition of previously frozen C, may determine the effect of permafrost thaw on CH4 emissions from northern peatlands.

  5. Ground penetrating radar estimates of permafrost ice wedge depth

    Science.gov (United States)

    Parsekian, A.; Slater, L. D.; Nolan, J. T.; Grosse, G.; Walter Anthony, K. M.

    2013-12-01

    Vertical ground ice wedges associated with polygonal patterning in permafrost environments form due to frost cracking of soils under harsh winter conditions and subsequent infilling of cracks with snow melt water. Ice wedge polygon patterns have implications for lowland geomorphology, hydrology, and vulnerability of permafrost to thaw. Ice wedge dimensions may exceed two meters width at the surface and several meters depth, however few studies have addressed the question of ice wedge depth due to challenges related to measuring the vertical dimension below the ground. Vertical exposures where ice wedges maybe observed are limited to rapidly retreating lake, river, and coastal bluffs. Coring though the ice wedges to determine vertical extent is possible, however that approach is time consuming and labor intensive. Many geophysical investigations have noted signal anomalies related to the presence of ice wedges, but no reliable method for extracting wedge dimensions from geophysical data has been yet proposed. Here we present new evidence that ground penetrating radar (GPR) may be a viable method for estimating ice wedge depth. We present three new perspectives on processing GPR data collected over ice wedges that show considerable promise for use as a fast, cost effective method for evaluating ice wedge depth. Our novel approaches include 1) a simple frequency-domain analysis, 2) an S-transform frequency domain analysis and 3) an analysis of the returned signal power as a radar cross section (RCS) treating subsurface ice wedges as dihedral corner retro-reflectors. Our methods are demonstrated and validated using finite-difference time domain FDTD) GPR forward models of synthetic idealized ice wedges and field data from permafrost sites in Alaska. Our results indicate that frequency domain and signal power data provide information that is easier to extract from raw GPR data than similar information in the time domain. We also show that we can simplify the problem by

  6. Degradation and modification of stainless-steel surface using Cl{sub 2}/Ar inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Hanbyeol [Dept. of Control and Instrumentation Engineering, Korea University, 2511 Sejong-Ro (Korea, Republic of); Efremov, Alexander [Dept. of Electronic Devices and Materials Technology, State University of Chemistry and Technology, 7 F. Engels st., 153000 Ivanovo (Russian Federation); Yun, Sun Jin [Electronic and Telecommunications Research Institute, Daejon 305-350 (Korea, Republic of); Yeom, Geun Young [Dept. of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Kyoung Bo [POSCO Global R and D Center, Open Innovation Lab., Incheon 406-840 (Korea, Republic of); Kwon, Kwang-Ho, E-mail: kwonkh@korea.ac.kr [Dept. of Control and Instrumentation Engineering, Korea University, 2511 Sejong-Ro (Korea, Republic of)

    2013-08-15

    The investigations of stainless steel (SS) etching behavior in the Cl{sub 2}/Ar inductively coupled plasma as well as the etched surface characteristics were carried out. It was found that an increase in Ar fraction in the Cl{sub 2}/Ar plasma from 0 to 100% at fixed gas pressure, input power and bias power results in decreasing both etching (degradation) rate of the SS surface (41.3–1.5 nm/min) and mean SS surface roughness (84–20 nm). Plasma diagnostics by Langmuir probes and 0-dimensional plasma modeling provided the data on plasma parameters, steady-state densities and fluxes of active species on the etched surface. It was shown that the maximum changes in mean roughness as well as in both polar and dispersive components of free surface energy correspond to a maximum value of Cl atom flux/ion flux ratio. Also, the linear correlation between free surface energy and mean roughness was obtained.

  7. Isolation, screening, and characterization of surface-active agent-producing, oil-degrading marine bacteria of Mumbai Harbor.

    Science.gov (United States)

    Mohanram, Rajamani; Jagtap, Chandrakant; Kumar, Pradeep

    2016-04-15

    Diverse marine bacterial species predominantly found in oil-polluted seawater produce diverse surface-active agents. Surface-active agents produced by bacteria are classified into two groups based on their molecular weights, namely biosurfactants and bioemulsifiers. In this study, surface-active agent-producing, oil-degrading marine bacteria were isolated using a modified Bushnell-Haas medium with high-speed diesel as a carbon source from three oil-polluted sites of Mumbai Harbor. Surface-active agent-producing bacterial strains were screened using nine widely used methods. The nineteen bacterial strains showed positive results for more than four surface-active agent screening methods; further, these strains were characterized using biochemical and nucleic acid sequencing methods. Based on the results, the organisms belonged to the genera Acinetobacter, Alcanivorax, Bacillus, Comamonas, Chryseomicrobium, Halomonas, Marinobacter, Nesterenkonia, Pseudomonas, and Serratia. The present study confirmed the prevalence of surface-active agent-producing bacteria in the oil-polluted waters of Mumbai Harbor. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Permafrost a změny klimatu

    Czech Academy of Sciences Publication Activity Database

    Mikuláš, Radek

    2005-01-01

    Roč. 84, č. 6 (2005), s. 345-347 ISSN 0042-4544 R&D Projects: GA AV ČR(CZ) KSK3046108 Keywords : permafrost * climate change * Holocene Subject RIV: DB - Geology ; Mineralogy http://www.vesmir.cz/clanek.php3?CID=6314

  9. Permafrost on tropical Maunakea volcano, Hawaii

    Science.gov (United States)

    Leopold, Matthias; Schorghofer, Norbert; Yoshikawa, Kenji

    2017-04-01

    Maunakea volcano on Hawaii Island is known for one of the most unusual occurrences of sporadic permafrost. It was first documented in two cinder cone craters in the 1970's near the summit of the mountain where mean annual air temperatures are currently around +4 deg. Our study investigates the current state of this permafrost, by acquiring multi-year ground temperature data and by applying electrical resistivity tomography and ground penetrating radar techniques along several survey lines. Both of the previously known ice bodies still exist, but one of them has dramatically shrunken in volume. Based on current warming trends it might disappear soon. In addition insolation modelling, temperature probing, and geomorphological indicators were used to prospect for additional permafrost bodies on the wider summit region, however, none was found. It seems that permafrost preferentially appears in the interiors of cinder cones, even though there are exterior slopes that receive less sunlight annually. We hypothesis that snow cover with its high albedo, and a layer of coarse boulders where cold air settles in the pore space during calm nights, play a significant role in cooling the subsurface. Due to the relatively simple setting, the study site is an ideal model system and may also serve as an analogue to Mars.

  10. Climate change and the permafrost carbon feedback

    NARCIS (Netherlands)

    Schuur, E. A G; McGuire, A. D.; Schädel, C.; Grosse, G.; Harden, J. W.; Hayes, D. J.; Hugelius, G.; Koven, C. D.; Kuhry, P.; Lawrence, D. M.; Natali, S. M.; Olefeldt, D.; Romanovsky, V. E.; Schaefer, K.; Turetsky, M. R.; Treat, C. C.; Vonk, J. E.|info:eu-repo/dai/nl/370832833

    2015-01-01

    Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This

  11. Evaluation of Degradation Kinetic of Tomato Paste Color in Heat Processing and Modeling of These Changes by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    M. Ganjeh

    2015-12-01

    Full Text Available Color is an important qualitative factor in tomato products such as tomato paste which is affected by heat processing. The main goal of this study was to evaluate the degradation kinetics of tomato paste color during heat processing by Arrhenius equation and modeling of these changes by response surface methodology (RSM. Considering this purpose, tomato paste was processed at three temperatures of 60, 70 and 80 °C for 25-100 minutes and by three main color indices including L, a and b, a/b ratio, total color difference (TCD, Saturation index (SI and hue angle (HU was analyzed. Degradation kinetics of these parameters was evaluated by Arrhenius equation and their changing trends were modeled by RSM. All parameters except TCA (zero order followed a first order reaction. The b index by highest and TCA and a/b by least activation energies had the maximum and minimum sensitivity to the temperature changes, respectively. Also, TCD and b had the maximum and minimum changing rates, respectively. All responses were influenced by independent parameters (the influence of temperature was more than time and RSM was capable of modeling and predicting these responses. In general, Arrhenius equation was appropriate to evaluate degradation kinetics of tomato paste color changes and RSM was able to estimate independent and interaction effects of time and temperature so that quadratic models were capable to predict these changes by a high accuracy (R2 > 0.95.

  12. CarboPerm: An interdisciplinary Russian-German scientific and technological cooperation project on the formation, turnover and release of carbon in Siberian permafrost landscapes

    Science.gov (United States)

    Zubrzycki, Sebastian

    2014-05-01

    Permafrost-affected soils of the northern hemisphere have accumulated large pools of organic carbon (OC) since continuous low temperatures in the permafrost prevented organic carbon decomposition. According to recent estimates these soils contain 1670 Pg of OC, or about 3-times the carbon within the atmosphere. Rising arctic temperatures will result in increased permafrost thawing resulting in a mobilization of formerly frozen OC. The degradation of the newly available OC will result in an increased formation of trace gases such as methane and carbon dioxide which can be released to the atmosphere. Rising trace gas concentrations due to permafrost thawing would thereby form a positive feedback on climate warming. CarboPerm, a 4.5 million Euro project for scientific and technological cooperation, is a joint German-Russian research project funded by the German Federal Ministry of Education and Research. It comprises multi-disciplinary investigations on the formation, turnover and release of OC in Siberian permafrost. It aims to gain increased understanding of how permafrost-affected landscapes will respond to global warming and how this response will influence the local, regional and global trace gas balance. Permafrost scientists from Russia and Germany will work together at different key sites in the Siberian Arctic. These sites are: the coast and islands at the Dmitry Laptev Strait, the Lena River Delta, and the Kolyma lowlands close to Cherskii. The scientific work packages comprise studies on (i) the origin, properties, and dynamics of fossil carbon, (ii) the age and quality of organic matter, (iii) the recent carbon dynamics in permafrost landscapes, (iv) the microbial transformation of organic carbon in permafrost, and (v) process-driven modeling of soil carbon dynamics in permafrost areas. The coordination will be at the University of Hamburg (scientific), the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research in Potsdam (logistic) and

  13. Characterising in situ activation and degradation of hindered amine light stabilisers using liquid extraction surface analysis-mass spectrometry.

    Science.gov (United States)

    Paine, Martin R L; Barker, Philip J; Blanksby, Stephen J

    2014-01-15

    Changes in the molecular structure of polymer antioxidants such as hindered amine light stabilisers (HALS) is central to their efficacy in retarding polymer degradation and therefore requires careful monitoring during their in-service lifetime. The HALS, bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate (TIN123) and bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate (TIN292), were formulated in different polymer systems and then exposed to various curing and ageing treatments to simulate in-service use. Samples of these coatings were then analysed directly using liquid extraction surface analysis (LESA) coupled with a triple quadrupole mass spectrometer. Analysis of TIN123 formulated in a cross-linked polyester revealed that the polymer matrix protected TIN123 from undergoing extensive thermal degradation that would normally occur at 292°C, specifically, changes at the 1- and 4-positions of the piperidine groups. The effect of thermal versus photo-oxidative degradation was also compared for TIN292 formulated in polyacrylate films by monitoring the in situ conversion of N-CH3 substituted piperidines to N-H. The analysis confirmed that UV light was required for the conversion of N-CH3 moieties to N-H - a major pathway in the antioxidant protection of polymers - whereas this conversion was not observed with thermal degradation. The use of tandem mass spectrometric techniques, including precursor-ion scanning, is shown to be highly sensitive and specific for detecting molecular-level changes in HALS compounds and, when coupled with LESA, able to monitor these changes in situ with speed and reproducibility. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Mercury's Crater-Hosted Hollows: Chalcogenide Pryo-Thermokarst, and Permafrost Analogs on Earth, Mars, and Titan

    Science.gov (United States)

    Kargel, Jeffrey

    2013-04-01

    MESSENGER has acquired stunning images of pitted, light-toned and variegated light/dark terrains located primarily on the floors—probably impact-melt sheets—of many of Mercury's large craters. Termed "hollows", the pitted terrains are geomorphologically similar to some on Mars formed by sublimation of ice-rich permafrost and to lowland thermokarst on Earth formed by permafrost thaw; to "swiss cheese" terrain forming by sublimation of frozen CO2 at the Martian South Pole; and to suspected hydrocarbon thermokarst at Titan's poles. I shall briefly review some analogs on these other worlds. The most plausible explanation for Mercury's hollows is terrain degradation involving melting or sublimation of heterogeneous chalcogenide and sulfosalt mineral assemblages. I refer to these Mercurian features as pyrothermokarst; the etymological redundancy distinguishes the conditions and mineral agents from the ice-related features on Earth and Mars, though some of the physical processes may be similar. Whereas ice and sulfur have long been suspected and ice recently was discovered in permanently shadowed craters of Mercury's polar regions, the hollows occur down to the equator, where neither ice nor sulfur is plausible. The responsible volatiles must be only slightly volatile on the surface and/or in the upper crust of Mercury's low to middle latitudes at 400-800 K, but they must be capable of either melting or sublimating on geologically long time scales. Under prevailing upper crustal and surface temperatures, chalcophile-rich "permafrost" can undergo either desulfidation or melting reactions that could cause migration or volume changes of the permafrost, and hence lead to collapse and pitting. I propose the initial emplacement of crater-hosted chalcogenides, sulfosalts and related chalcophile materials such as pnictides, in impact-melt pools (involving solid-liquid and silicate-sulfide fractionation) and further differentiation by associated dry or humid fumaroles (solid

  15. River Export of Dissolved and Particulate Organic Carbon from Permafrost and Peat Deposits across the Siberian Arctic

    Science.gov (United States)

    Wild, B.; Andersson, A.; Bröder, L.; Vonk, J.; Hugelius, G.; McClelland, J. W.; Raymond, P. A.; Gustafsson, O.

    2017-12-01

    Permafrost and peat deposits of northern high latitudes store more than 1300 Pg of organic carbon. This carbon has been preserved for thousands of years by cold and moist conditions, but is now increasingly mobilized as temperatures rise. While part will be degraded to CO2 and CH4 and amplify global warming, part will be exported by rivers to the Arctic Ocean where it can be degraded or re-buried by sedimentation. We here use the four large Siberian rivers Ob, Yenisey, Lena, and Kolyma as natural integrators of carbon mobilization in their catchments. We apply isotope based source apportionments and Markov Chain Monte Carlo Simulations to quantify contributions of organic carbon from permafrost and peat deposits to organic carbon exported by these rivers. More specifically, we compare the 14C signatures of dissolved and particulate organic carbon (DOC, POC) sampled close to the river mouths with those of five potential carbon sources; (1) recent aquatic and (2) terrestrial primary production, (3) the active layer of permafrost soils, (4) deep Holocene deposits (including thermokarst and peat deposits) and (5) Ice Complex Deposits. 14C signatures of these endmembers were constrained based on extensive literature review. We estimate that the four rivers together exported 2.4-4.5 Tg organic carbon from permafrost and peat deposits per year. While total organic carbon export was dominated by DOC (90%), the export of organic carbon from permafrost and peat deposits was more equally distributed between DOC (56%) and POC (44%). Recent models predict that ca. 200 Pg carbon will be lost as CO2 or CH4 by 2100 (RCP8.5) from the circumarctic permafrost area, of which roughly a quarter is drained by the Ob, Yenisey, Lena, and Kolyma rivers. Our comparatively low estimates of river carbon export thus suggest limited transfer of organic carbon from permafrost and peat deposits to high latitude rivers, or its rapid degradation within rivers. Our findings highlight the importance

  16. Degradation of surface-labeled hepatoma membrane polypeptides: effect of inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Hare, J.F.; Huston, M.

    1984-09-01

    When their membrane proteins were labeled with 125I by lactoperoxidase, dividing hepatoma cells lost radioactivity to the medium in a biphasic manner (T1/2 . 16-26 h, greater than 40 h). Lysosomotropic weak bases, chloroquine, and NH4Cl inhibited the rapid phase by 59%. More than 50% of the radioactivity which accumulates in the media from dividing cells during the first 4 h after labeling was trichloroacetic acid-soluble, and was identified as iodotyrosine. Iodotyrosine release from labeled membrane proteins was 60-71% inhibited by lysosomotropic agents chloroquine and NH4Cl as well as the sodium-proton ionophore, monensin. The inhibitory effect of NH4Cl and monensin was reversible. Inhibitors of microtubule and microfilament function and transglutamination had no effect on release of iodotyrosine to the medium, but trypsin-like protease inhibitors, p-aminobenzamidine, tosyl-L-lysine/chloromethylketone, and phenylmethylsulfonyl fluoride, as well as the cathepsin B inhibitor, leupeptin, inhibited by 21-24%. Iodotyrosine release showed a biphasic Arrhenius plot with an activation energy of 17 kcal/mol above but 27 kcal/mol below 20 degrees C. These results indicate that cell membrane polypeptides require a temperature-limiting event as well as passage through an ion-sensitive compartment prior to their complete degradation to constituent amino acids. In contrast to other lysosomal-mediated events, however, iodinated membrane proteins of dividing cells are degraded in a manner insensitive to agents which disrupt the cytoskeleton.

  17. Effect of chemical degradation followed by toothbrushing on the surface roughness of restorative composites

    Directory of Open Access Journals (Sweden)

    Fernanda Regina Voltarelli

    2010-12-01

    Full Text Available OBJECTIVES: The aim of the present study was to assess the effect of the exposure to food-simulating liquids prior to brushing simulation on the surface roughness of five composite materials (Quixfil, Filtek Supreme, Esthet-X, Filtek Z250, Tetric Ceram. Material and METHODS: Twenty cylinders (5 mm diameter and 4 mm height of each composite were randomly allocated to 4 groups (n=5, according to the food-simulating liquid in which they were immersed for 7 days at 37°C: artificial saliva, heptane, citric acid, and ethanol. After this period, the top surface of composite cylinders was submitted to 7,500 brushing cycles (200 g load. Measurements of the surface roughness (Ra, ¼m were carried out before and after the exposure to the chemicals/brushing simulation. Changes on the morphology of composite surfaces were observed through scanning electron microscopy (SEM. RESULTS: The statistical analysis (ANOVA with cofactor / Tukey's test, α=5% detected a significant interaction between solutions and composite resins. Esthet-X, Filtek Z250 and Tetric Ceram were not affected by the food-simulating liquids/toothbrushing. Citric acid and ethanol increased the surface roughness of Quixfil and Filtek Supreme, respectively. SEM images corroborate the surface roughness findings, demonstrating the negative effect from chemical solutions and mechanical abrasion. CONCLUSIONS: The surface roughness of composite resin materials are differently affected by the food-simulating solutions, depending on the immersion media.

  18. Effect of chemical degradation followed by toothbrushing on the surface roughness of restorative composites

    Science.gov (United States)

    VOLTARELLI, Fernanda Regina; dos SANTOS-DAROZ, Claudia Batitucci; ALVES, Marcelo Corrêa; CAVALCANTI, Andrea Nóbrega; MARCHI, Giselle Maria

    2010-01-01

    Objectives The aim of the present study was to assess the effect of the exposure to food-simulating liquids prior to brushing simulation on the surface roughness of five composite materials (Quixfil, Filtek Supreme, Esthet-X, Filtek Z250, Tetric Ceram). Material and methods Twenty cylinders (5 mm diameter and 4 mm height) of each composite were randomly allocated to 4 groups (n=5), according to the food-simulating liquid in which they were immersed for 7 days at 37ºC: artificial saliva, heptane, citric acid, and ethanol. After this period, the top surface of composite cylinders was submitted to 7,500 brushing cycles (200 g load). Measurements of the surface roughness (Ra, µm) were carried out before and after the exposure to the chemicals/brushing simulation. Changes on the morphology of composite surfaces were observed through scanning electron microscopy (SEM). Results The statistical analysis (ANOVA with cofactor / Tukey's test, α=5%) detected a significant interaction between solutions and composite resins. Esthet-X, Filtek Z250 and Tetric Ceram were not affected by the food-simulating liquids/toothbrushing. Citric acid and ethanol increased the surface roughness of Quixfil and Filtek Supreme, respectively. SEM images corroborate the surface roughness findings, demonstrating the negative effect from chemical solutions and mechanical abrasion. Conclusions The surface roughness of composite resin materials are differently affected by the food-simulating solutions, depending on the immersion media. PMID:21308289

  19. Surface interactions and degradation of a fluoroquinolone antibiotic in the dark in aqueous TiO{sub 2} suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Jonathan W., E-mail: peterson@hope.edu [Department of Geological & Environmental Sciences, Hope College, P.O. Box 9000, Holland, MI 49422-9000 (United States); Gu, Baohua [Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Seymour, Michael D. [Department of Chemistry, Hope College, P.O. Box 9000, Holland, MI 49422-9000 (United States)

    2015-11-01

    Fluoroquinolone antibiotics (FQs) are important drugs used in human and veterinary medicine. Their detection in natural waters and waste water treatment plants, along with increased resistance to FQs among some bacteria, have generated an increased interest in the fate of these drugs in the environment. Partitioning of FQs between an aqueous solution and attendant substrates depends, in part, on the surface reactivity of the adsorbent, commonly a function of particle size, surface charge, and functional groups. This study investigated the surface interactions between the FQ drug ofloxacin (OFL) and titanium oxide (TiO{sub 2}), a common catalyst and widely-observed constituent in many consumer products. Raman and fluorescence spectroscopic techniques, as well as LC/MS, were used to determine the OFL moieties present on TiO{sub 2} surfaces and in attendant solutions. Raman spectra indicate that the C=O (ketone) group of the quinolone core, the NH{sup +} of the piperazinyl ring, and CH{sub 3} of benzoxazine core are the most active in sorption onto the TiO{sub 2} surface. Raman spectra also show that the sorbed benzoxazine–quinolone core and piperazinyl moieties are readily desorbed from the surface by re-suspending samples in water. Importantly, we found that OFL could be degraded by reacting with TiO{sub 2} even in the dark. Complementary LC/MS analysis of the attendant supernatants indicates the presence of de-piperazinylated and de-carboxylated OFL breakdown products in supernatant solutions. Together, both Raman and LC/MS analyses indicate that TiO{sub 2} breaks the compound into piperazinyl and carboxylate groups which attach to the surface, whereas de-carboxylated and hydroxylated quinolone moieties remain in solution. The present study thus identifies the sorption mechanisms and breakdown products of OFL during dark reactions with TiO{sub 2}, which is critically important for understanding the fate and transport of OFL as it enters the soil and aquatic

  20. Comparative investigation on a hexane-degrading strain with different cell surface hydrophobicities mediated by starch and chitosan.

    Science.gov (United States)

    Chen, Dong-Zhi; Jiang, Ning-Xin; Ye, Jie-Xu; Cheng, Zhuo-Wei; Zhang, Shi-Han; Chen, Jian-Meng

    2017-05-01

    Bioremediation usually exhibits low removal efficiency toward hexane because of poor water solubility, which limits the mass transfer rate between the substrate and microorganism. This work aimed to enhance the hexane degradation rate by increasing cell surface hydrophobicity (CSH) of the degrader, Pseudomonas mendocina NX-1. The CSH of P. mendocina NX-1 was manipulated by treatment with starch and chitosan solution of varied concentrations, reaching a maximum hydrophobicity of 52%. The biodegradation of hexane conformed to the Haldane inhibition model, and the maximum degradation rate (ν max ) of the cells with 52% CSH was 0.72 mg (mg cell) -1 ·h -1 in comparison with 0.47 mg (mg cell) -1 ·h -1 for cells with 15% CSH. The production of CO 2 by high CSH cells was threefold higher than that by cells at 15% CSH within 30 h, and the cumulative rates of O 2 consumption were 0.16 and 0.05 mL/h, respectively. High CSH was related to low negative charge carried by the cell surface and probably reduced the repulsive electrostatic interactions between hexane and microorganisms. The FT-IR spectra of cell envelopes demonstrated that the methyl chain was inversely proportional to increasing CSH values, but proteins exhibited a positive effect to CSH enhancement. The ratio of extracellular proteins and polysaccharides increased from 0.87 to 3.78 when the cells were treated with starch and chitosan, indicating their possible roles in increased CSH.

  1. Determination of the mechanism and extent of surface degradation in Ni-based cathode materials after repeated electrochemical cycling

    Directory of Open Access Journals (Sweden)

    Sooyeon Hwang

    2016-09-01

    Full Text Available We take advantage of scanning transmission electron microscopy and electron energy loss spectroscopy to investigate the changes in near-surface electronic structure and quantify the degree of local degradation of Ni-based cathode materials with the layered structure (LiNi0.8Mn0.1Co0.1O2 and LiNi0.4Mn0.3Co0.3O2 after 20 cycles of delithiation and lithiation. Reduction of transition metals occurs in the near-surface region of cathode materials: Mn is the major element to be reduced in the case of relatively Mn-rich composition, while reduction of Ni ions is dominant in Ni-rich materials. The valences of Ni and Mn ions are complementary, i.e., when one is reduced, the other is oxidized in order to maintain charge neutrality. The depth of degradation zone is found to be much deeper in Ni-rich materials. This comparative analysis provides important insights needed for the devising of new cathode materials with high capacity as well as long lifetime.

  2. Phototrophic pigment diversity and picophytoplankton in permafrost thaw lakes

    Science.gov (United States)

    Przytulska, A.; Comte, J.; Crevecoeur, S.; Lovejoy, C.; Laurion, I.; Vincent, W. F.

    2016-01-01

    Permafrost thaw lakes (thermokarst lakes) are widely distributed across the northern landscape, and are known to be biogeochemically active sites that emit large amounts of carbon to the atmosphere as CH4 and CO2. However, the abundance and composition of the photosynthetic communities that fix CO2 have been little explored in this ecosystem type. In order to identify the major groups of phototrophic organisms and their controlling variables, we sampled 12 permafrost thaw lakes along a permafrost degradation gradient in northern Québec, Canada. Additional samples were taken from five rock-basin reference lakes in the region to determine if the thaw lakes differed in limnological properties and phototrophs. Phytoplankton community structure was determined by high-performance liquid chromatography analysis of their photoprotective and photosynthetic pigments, and autotrophic picoplankton concentrations were assessed by flow cytometry. One of the black-colored lakes located in a landscape of rapidly degrading palsas (permafrost mounds) was selected for high-throughput 18S rRNA sequencing to complement conclusions based on the pigment and cytometry analyses. The results showed that the limnological properties of the thaw lakes differed significantly from the reference lakes, and were more highly stratified. However, both waterbody types contained similarly diverse phytoplankton groups, with dominance of the pigment assemblages by fucoxanthin-containing taxa, as well as chlorophytes, cryptophytes and cyanobacteria. Chlorophyll a concentrations (Chl a) were correlated with total phosphorus (TP), and both were significantly higher in the thaw lakes (overall means of 3.3 µg Chl a L-1 and 34 µg TP L-1) relative to the reference lakes (2.0 µg Chl a L-1 and 8.2 µg TP L-1). Stepwise multiple regression of Chl a against the other algal pigments showed that it was largely a function of alloxanthin, fucoxanthin and Chl b (R2 = 0.85). The bottom waters of two of the thaw

  3. Degradation of Perfluorinated Ether Lubricants on Pure Aluminum Surfaces: Semiempirical Quantum Chemical Modeling

    Science.gov (United States)

    Slaby, Scott M.; Ewing, David W.; Zehe, Michael J.

    1997-01-01

    The AM1 semiempirical quantum chemical method was used to model the interaction of perfluoroethers with aluminum surfaces. Perfluorodimethoxymethane and perfluorodimethyl ether were studied interacting with aluminum surfaces, which were modeled by a five-atom cluster and a nine-atom cluster. Interactions were studied for edge (high index) sites and top (low index) sites of the clusters. Both dissociative binding and nondissociative binding were found, with dissociative binding being stronger. The two different ethers bound and dissociated on the clusters in different ways: perfluorodimethoxymethane through its oxygen atoms, but perfluorodimethyl ether through its fluorine atoms. The acetal linkage of perfluorodimeth-oxymethane was the key structural feature of this molecule in its binding and dissociation on the aluminum surface models. The high-index sites of the clusters caused the dissociation of both ethers. These results are consistent with the experimental observation that perfluorinated ethers decompose in contact with sputtered aluminum surfaces.

  4. Threshold sensitivity of shallow Arctic lakes and sublake permafrost to changing winter climate

    Science.gov (United States)

    Arp, Christopher D.; Jones, Benjamin M.; Grosse, Guido; Bondurant, Allen C.; Romanovksy, Vladimir E.; Hinkel, Kenneth M.; Parsekian, Andrew D.

    2016-01-01

    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.

  5. Uranium isotopes and dissolved organic carbon in loess permafrost: Modeling the age of ancient ice

    Science.gov (United States)

    Ewing, Stephanie A.; Paces, James B.; O'Donnell, J.A.; Jorgenson, M.T.; Kanevskiy, M.Z.; Aiken, George R.; Shur, Y.; Harden, Jennifer W.; Striegl, Robert G.

    2015-01-01

    The residence time of ice in permafrost is an indicator of past climate history, and of the resilience and vulnerability of high-latitude ecosystems to global change. Development of geochemical indicators of ground-ice residence times in permafrost will advance understanding of the circumstances and evidence of permafrost formation, preservation, and thaw in response to climate warming and other disturbance. We used uranium isotopes to evaluate the residence time of segregated ground ice from ice-rich loess permafrost cores in central Alaska. Activity ratios of 234U vs. 238U (234U/238U) in water from thawed core sections ranged between 1.163 and 1.904 due to contact of ice and associated liquid water with mineral surfaces over time. Measured (234U/238U) values in ground ice showed an overall increase with depth in a series of five neighboring cores up to 21 m deep. This is consistent with increasing residence time of ice with depth as a result of accumulation of loess over time, as well as characteristic ice morphologies, high segregated ice content, and wedge ice, all of which support an interpretation of syngenetic permafrost formation associated with loess deposition. At the same time, stratigraphic evidence indicates some past sediment redistribution and possibly shallow thaw among cores, with local mixing of aged thaw waters. Using measures of surface area and a leaching experiment to determine U distribution, a geometric model of (234U/238U) evolution suggests mean ages of up to ∼200 ky BP in the deepest core, with estimated uncertainties of up to an order of magnitude. Evidence of secondary coatings on loess grains with elevated (234U/238U) values and U concentrations suggests that refinement of the geometric model to account for weathering processes is needed to reduce uncertainty. We suggest that in this area of deep ice-rich loess permafrost, ice bodies have been preserved from the last glacial period (10–100 ky BP), despite subsequent

  6. Surface engineering of polyester-degrading enzymes to improve efficiency and tune specificity.

    Science.gov (United States)

    Biundo, Antonino; Ribitsch, Doris; Guebitz, Georg M

    2018-04-01

    Certain members of the carboxylesterase superfamily can act at the interface between water and water-insoluble substrates. However, nonnatural bulky polyesters usually are not efficiently hydrolyzed. In the recent years, the potential of enzyme engineering to improve hydrolysis of synthetic polyesters has been demonstrated. Regions on the enzyme surface have been modified by using site-directed mutagenesis in order to tune sorption processes through increased hydrophobicity of the enzyme surface. Such modifications can involve specific amino acid substitutions, addition of binding modules, or truncation of entire domains improving sorption properties and/or dynamics of the enzyme. In this review, we provide a comprehensive overview on different strategies developed in the recent years for enzyme surface engineering to improve the activity of polyester-hydrolyzing enzymes.

  7. Hydrophobic dielectric surface influenced active layer thickness effect on hysteresis and mobility degradation in organic field effect transistors

    Science.gov (United States)

    Padma, N.

    2016-02-01

    Effect of active layer thickness, influenced by the hydrophobic dielectric surface, on the performance of copper phthalocyanine based organic field effect transistors (OFETs) was studied. While charge carrier mobility was found to be highest for an optimum thickness of 30 nm, hysteresis and threshold voltage shift were found to be minimum for 15 nm thick film which is attributed to the excess availability of photogenerated carriers, especially close to the dielectric/semiconductor interface, as this thickness is within the exciton quenching length in organic semiconductors. But prolonged bias stress resulted in larger decay in drain current for higher thickness indicating the dominant role played by the larger grain boundary density in the increased volume. These results were found to be different from that on unmodified SiO2 dielectric with higher surface energy and were suggested to be caused by the 3D growth mode of CuPc films on the hydrophobic surface. Mobility degradation at higher gate voltages also exhibited a dependence on the active layer thickness which was tuned by the hydrophobic surface induced growth mode at the dielectric/semiconductor interface.

  8. The Importance of Permafrost Thaw, Fire and Logging Disturbances as Driving Factors of Historical and Projected Carbon Dynamics in Alaskan Ecosystems

    Science.gov (United States)

    Genet, H.; Zhang, Y.; McGuire, A. D.; He, Y.; Johnson, K. D.; D'Amore, D. V.; Zhou, X.; Bennett, A.; Breen, A. L.; Biles, F. E.; Bliss, N. B.; Euskirchen, E. S.; Kurkowski, T. A.; Pastick, N.; Rupp, S. T.; Wylie, B. K.; Zhu, Z.; Zhuang, Q.

    2014-12-01

    Carbon dynamics of natural ecosystems are influenced by disturbance regimes of various frequencies and magnitudes. With global change, these disturbances are projected to increase in frequency and/or magnitude and may have significant effects on future net carbon balance, especially in high latitude ecosystems where carbon stocks are among the largest on Earth and climate change is substantial. In Alaska, permafrost degradation and fire in the boreal and arctic regions and logging in the southern coastal region are the main disturbances that affect ecosystems. Large uncertainties related to the effects of these disturbances on the capacity of these regions to store carbon still exist mainly due to difficulty in representing permafrost degradation in current ecosystem models. We ran the Terrestrial Ecosystem Model (TEM), which explicitly simulates the carbon cycle and permafrost dynamics, coupled with a disturbance model (the Alaska Frame Based Ecosystem Code, ALFRESCO) to assess the relative importance of permafrost thaw, wildfire, and forest management on historical and projected carbon balance and carbon stocks in Alaska, from 1950 to 2100, at a 1-km resolution. Our simulations showed that the increase in plant productivity in response to warming in boreal and arctic regions is offset by soil carbon loss due to permafrost degradation and wildfire combustion during both historical and future simulations. Fire disturbances act as a catalyst accelerating permafrost degradation and associated soil carbon loss. In addition, our preliminary results for south coastal regions of Alaska indicate that logging of second growth forests could influence carbon dynamics in that region. Overall, these results have implications for land management strategies and illustrate the importance of taking into account multiple types of disturbance regimes in ecosystem models for Alaska.

  9. Cooperative degradation of chitin by extracellular and cell surface-expressed chitinases from Paenibacillus sp. strain FPU-7.

    Science.gov (United States)

    Itoh, Takafumi; Hibi, Takao; Fujii, Yutaka; Sugimoto, Ikumi; Fujiwara, Akihiro; Suzuki, Fumiko; Iwasaki, Yukimoto; Kim, Jin-Kyung; Taketo, Akira; Kimoto, Hisashi

    2013-12-01

    Chitin, a major component of fungal cell walls and invertebrate cuticles, is an exceedingly abundant polysaccharide, ranking next to cellulose. Industrial demand for chitin and its degradation products as raw materials for fine chemical products is increasing. A bacterium with high chitin-decomposing activity, Paenibacillus sp. strain FPU-7, was isolated from soil by using a screening medium containing α-chitin powder. Although FPU-7 secreted several extracellular chitinases and thoroughly digested the powder, the extracellular fluid alone broke them down incompletely. Based on expression cloning and phylogenetic analysis, at least seven family 18 chitinase genes were found in the FPU-7 genome. Interestingly, the product of only one gene (chiW) was identified as possessing three S-layer homology (SLH) domains and two glycosyl hydrolase family 18 catalytic domains. Since SLH domains are known to function as anchors to the Gram-positive bacterial cell surface, ChiW was suggested to be a novel multimodular surface-expressed enzyme and to play an important role in the complete degradation of chitin. Indeed, the ChiW protein was localized on the cell surface. Each of the seven chitinase genes (chiA to chiF and chiW) was cloned and expressed in Escherichia coli cells for biochemical characterization of their products. In particular, ChiE and ChiW showed high activity for insoluble chitin. The high chitinolytic activity of strain FPU-7 and the chitinases may be useful for environmentally friendly processing of chitin in the manufacture of food and/or medicine.

  10. Synthesis of surface plasmon resonance (SPR) triggered Ag/TiO2 photocatalyst for degradation of endocrine disturbing compounds

    International Nuclear Information System (INIS)

    Leong, Kah Hon; Gan, Bee Ling; Ibrahim, Shaliza; Saravanan, Pichiah

    2014-01-01

    Graphical abstract: - Highlights: • Ag/TiO 2 was synthesized with aid of natural photon stimulated photoreduction. • Deposited Ag prompted well the LSPRs, Schottky barrier for visible light utilization. • Photocatalytic activity was evaluated by degrading EDCs under visible light. • 3.0 wt% Ag/TiO 2 resulted with good photocatalytic efficiency over others. - Abstract: Surface deposition of silver nanoparticles (Ag NPs) onto the 100% anatase titania (Ag/TiO 2 ) for evolution of surface plasmon resonance (SPR) was achieved sustainably with the assistance of solar energy. The preparation resulted in Ag/TiO 2 photocatalyst with varied Ag depositions (0.5 wt%, 1.0 wt%, 3.0 wt% and 5.0 wt%). All obtained photocatalysts were characterized for the evolution of SPR via crystalline phase analysis, morphology, lattice fringes, surface area and pore size characteristics, chemical composition with chemical and electronic state, Raman scattering, optical and photoluminescence properties. The deposition of synthesized Ag NPs exhibited high uniformity and homogeneity and laid pathway for effective utilization of the visible region of electromagnetic spectrum through SPR. The depositions also lead for suppressing recombination rates of electron–hole. The photocatalytic evaluation was carried out by adopting two different class of endocrine disturbing compound (EDC) i.e., amoxicillin (pharmaceutical) and 2,4-dichlorophenol (pesticide) excited with artificial visible light source. Ag/TiO 2 with Ag > 0.5 wt% exhibited significant degradation efficiency for both amoxicillin and 2,4-dichlorophenol. Thus synthesized Ag/TiO 2 revealed the implication of plasmonics on TiO 2 for the enhanced visible light photocatalytic activity

  11. Synthesis of surface plasmon resonance (SPR) triggered Ag/TiO{sub 2} photocatalyst for degradation of endocrine disturbing compounds

    Energy Technology Data Exchange (ETDEWEB)

    Leong, Kah Hon; Gan, Bee Ling; Ibrahim, Shaliza [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Saravanan, Pichiah, E-mail: saravananpichiah@um.edu.my [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nanotechnology and Catalysis Research Center (NANOCAT), University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-11-15

    Graphical abstract: - Highlights: • Ag/TiO{sub 2} was synthesized with aid of natural photon stimulated photoreduction. • Deposited Ag prompted well the LSPRs, Schottky barrier for visible light utilization. • Photocatalytic activity was evaluated by degrading EDCs under visible light. • 3.0 wt% Ag/TiO{sub 2} resulted with good photocatalytic efficiency over others. - Abstract: Surface deposition of silver nanoparticles (Ag NPs) onto the 100% anatase titania (Ag/TiO{sub 2}) for evolution of surface plasmon resonance (SPR) was achieved sustainably with the assistance of solar energy. The preparation resulted in Ag/TiO{sub 2} photocatalyst with varied Ag depositions (0.5 wt%, 1.0 wt%, 3.0 wt% and 5.0 wt%). All obtained photocatalysts were characterized for the evolution of SPR via crystalline phase analysis, morphology, lattice fringes, surface area and pore size characteristics, chemical composition with chemical and electronic state, Raman scattering, optical and photoluminescence properties. The deposition of synthesized Ag NPs exhibited high uniformity and homogeneity and laid pathway for effective utilization of the visible region of electromagnetic spectrum through SPR. The depositions also lead for suppressing recombination rates of electron–hole. The photocatalytic evaluation was carried out by adopting two different class of endocrine disturbing compound (EDC) i.e., amoxicillin (pharmaceutical) and 2,4-dichlorophenol (pesticide) excited with artificial visible light source. Ag/TiO{sub 2} with Ag > 0.5 wt% exhibited significant degradation efficiency for both amoxicillin and 2,4-dichlorophenol. Thus synthesized Ag/TiO{sub 2} revealed the implication of plasmonics on TiO{sub 2} for the enhanced visible light photocatalytic activity.

  12. Land Resources of Russia -- Maps of Permafrost and Ground Ice, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes maps of permafrost extent, permafrost temperature, the permafrost boundary, and ground ice thickness for all of Russia. The maps are ESRI...

  13. Influence of mechanical and chemical degradation on surface gloss of resin composite materials

    NARCIS (Netherlands)

    Ardu, S.; Braut, V.; Uhac, I.; Benbachir, N.; Feilzer, A.J.; Krejci, I.

    2009-01-01

    Purpose: To determine the changes in surface gloss of different composite materials after simulation of mechanical and chemical aging mechanisms. Methods: 36 specimens were fabricated for each material and polished with 120-, 220-, 500-, 1200-, 2400- and 4000- grit SiC abrasive paper, respectively.

  14. Effects of photovoltaic module soiling on glass surface resistance and potential-induced degradation

    DEFF Research Database (Denmark)

    Hacke, Peter; Burton, Patrick; Hendrickson, Alexander

    2015-01-01

    The sheet resistance of three soil types (Arizona road dust, soot, and sea salt) on glass were measured by the transmission line method as a function of relative humidity (RH) between 39% and 95% at 60°C. Sea salt yielded a 3.5 orders of magnitude decrease in resistance on the glass surface when ...

  15. Mechanical, Thermal Degradation, and Flammability Studies on Surface Modified Sisal Fiber Reinforced Recycled Polypropylene Composites

    Directory of Open Access Journals (Sweden)

    Arun Kumar Gupta

    2012-01-01

    Full Text Available The effect of surface treated sisal fiber on the mechanical, thermal, flammability, and morphological properties of sisal fiber (SF reinforced recycled polypropylene (RPP composites was investigated. The surface of sisal fiber was modified with different chemical reagent such as silane, glycidyl methacrylate (GMA, and O-hydroxybenzene diazonium chloride (OBDC to improve the compatibility with the matrix polymer. The experimental results revealed an improvement in the tensile strength to 11%, 20%, and 31.36% and impact strength to 78.72%, 77%, and 81% for silane, GMA, and OBDC treated sisal fiber reinforced recycled Polypropylene (RPP/SF composites, respectively, as compared to RPP. The thermogravimetric analysis (TGA, differential scanning calorimeter (DSC, and heat deflection temperature (HDT results revealed improved thermal stability as compared with RPP. The flammability behaviour of silane, GMA, and OBDC treated SF/RPP composites was studied by the horizontal burning rate by UL-94. The morphological analysis through scanning electron micrograph (SEM supports improves surface interaction between fiber surface and polymer matrix.

  16. The impact of oxic degradation on long chain alkyl diol distributions in Arabian Sea surface sediments

    NARCIS (Netherlands)

    Rodrigo-Gámiz, M.; Rampen, S.W.; Schouten, S.; Sinninghe Damsté, J.S.

    2016-01-01

    Oxygen exposure has a large impact on lipid biomarker preservation in surface sediments and may affectthe application of organic proxies used for reconstructing past environmental conditions. To determineits effect on long chain alkyl diol and keto-ol based proxies, the distributions of these lipids

  17. The impact of oxic degradation on long chain alkyl diol distributions in Arabian Sea surface sediments

    NARCIS (Netherlands)

    Rodrigo-Gámiz, M.; Rampen, Sebastiaan W.; Schouten, S.; Sinninghe Damsté, J.S.

    2016-01-01

    Oxygen exposure has a large impact on lipid biomarker preservation in surface sediments and may affect the application of organic proxies used for reconstructing past environmental conditions. To determine its effect on long chain alkyl diol and keto-ol based proxies, the distributions of these

  18. Endothelial surface layer degradation by chronic hyaluronidase infusion induces proteinuria in apolipoprotein e-deficient mice

    NARCIS (Netherlands)

    Meuwese, Marijn C.; Broekhuizen, Lysette N.; Kuikhoven, Mayella; Heeneman, Sylvia; Lutgens, Esther; Gijbels, Marion J. J.; Nieuwdorp, Max; Peutz, Carine J.; Stroes, Erik S. G.; Vink, Hans; van den Berg, Bernard M.

    2010-01-01

    Functional studies show that disruption of endothelial surface layer (ESL) is accompanied by enhanced sensitivity of the vasculature towards atherogenic stimuli. However, relevance of ESL disruption as causal mechanism for vascular dysfunction remains to be demonstrated. We examined if loss of ESL

  19. Semiautomatic mapping of permafrost in the Yukon Flats, Alaska

    Science.gov (United States)

    Gulbrandsen, Mats Lundh; Minsley, Burke J.; Ball, Lyndsay B.; Hansen, Thomas Mejer

    2016-01-01

    Thawing of permafrost due to global warming can have major impacts on hydrogeological processes, climate feedback, arctic ecology, and local environments. To understand these effects and processes, it is crucial to know the distribution of permafrost. In this study we exploit the fact that airborne electromagnetic (AEM) data are sensitive to the distribution of permafrost and demonstrate how the distribution of permafrost in the Yukon Flats, Alaska, is mapped in an efficient (semiautomatic) way, using a combination of supervised and unsupervised (machine) learning algorithms, i.e., Smart Interpretation and K-means clustering. Clustering is used to sort unfrozen and frozen regions, and Smart Interpretation is used to predict the depth of permafrost based on expert interpretations. This workflow allows, for the first time, a quantitative and objective approach to efficiently map permafrost based on large amounts of AEM data.

  20. Guidance proposal for using available DegT50 values for estimation of degradation rates of plant protection products in Dutch surface water and sediment

    NARCIS (Netherlands)

    Boesten, J.J.T.I.; Adriaanse, P.I.; Horst, ter M.M.S.; Tiktak, A.; Linden, van der A.M.A.

    2014-01-01

    The degradation rate of plant protection products and their transformation products in surface water and sediment may influence their concentrations in Dutch surface water. Therefore the estimation of these rates may be an important part of the assessment of the exposure of aquatic organisms. We

  1. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Steve Runyon; Richard Sigal; Bill Liddell; Thomas Williams; George Moridis

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. Hot Ice No. 1 was planned to test the Ugnu and West Sak sequences for gas hydrates and a concomitant free gas accumulation on Anadarko's 100% working interest acreage in section 30 of Township 9N, Range 8E of the Harrison Bay quadrangle of the North Slope of Alaska. The Ugnu and West Sak intervals are favorably positioned in the hydrate-stability zone over an area extending from Anadarko's acreage westward to the vicinity of the aforementioned gas-hydrate occurrences. This suggests that a large, north-to-south trending gas-hydrate accumulation may exist in that area. The presence of gas shows in the Ugnu and West Sak reservoirs in wells situated eastward and down dip of the Hot Ice location indicate that a free-gas accumulation may be trapped by gas hydrates. The Hot Ice No. 1 well was designed to core from the surface to the base of the West Sak interval using the

  2. Data-driven mapping of the potential mountain permafrost distribution.

    Science.gov (United States)

    Deluigi, Nicola; Lambiel, Christophe; Kanevski, Mikhail

    2017-07-15

    Existing mountain permafrost distribution models generally offer a good overview of the potential extent of this phenomenon at a regional scale. They are however not always able to reproduce the high spatial discontinuity of permafrost at the micro-scale (scale of a specific landform; ten to several hundreds of meters). To overcome this lack, we tested an alternative modelling approach using three classification algorithms belonging to statistics and machine learning: Logistic regression, Support Vector Machines and Random forests. These supervised learning techniques infer a classification function from labelled training data (pixels of permafrost absence and presence) with the aim of predicting the permafrost occurrence where it is unknown. The research was carried out in a 588km 2 area of the Western Swiss Alps. Permafrost evidences were mapped from ortho-image interpretation (rock glacier inventorying) and field data (mainly geoelectrical and thermal data). The relationship between selected permafrost evidences and permafrost controlling factors was computed with the mentioned techniques. Classification performances, assessed with AUROC, range between 0.81 for Logistic regression, 0.85 with Support Vector Machines and 0.88 with Random forests. The adopted machine learning algorithms have demonstrated to be efficient for permafrost distribution modelling thanks to consistent results compared to the field reality. The high resolution of the input dataset (10m) allows elaborating maps at the micro-scale with a modelled permafrost spatial distribution less optimistic than classic spatial models. Moreover, the probability output of adopted algorithms offers a more precise overview of the potential distribution of mountain permafrost than proposing simple indexes of the permafrost favorability. These encouraging results also open the way to new possibilities of permafrost data analysis and mapping. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Assessing hazard risk, cost of adaptation and traditional land use activities in the context of permafrost thaw in communities in Yukon and the Northwest Territories, Canada

    Science.gov (United States)

    Benkert, B.; Perrin, A.; Calmels, F.

    2015-12-01

    Together with its partners, the Northern Climate ExChange (NCE, part of the Yukon Research Centre at Yukon College) has been mapping permafrost-related hazard risk in northern communities since 2010. By integrating geoscience and climate project data, we have developed a series of community-scale hazard risk maps. The maps depict hazard risk in stoplight colours for easy interpretation, and support community-based, future-focused adaptation planning. Communities, First Nations, consultants and local regulatory agencies have used the hazard risk maps to site small-scale infrastructure projects, guide land planning processes, and assess suitability of land development applications. However, we know that assessing risk is only one step in integrating the implications of permafrost degradation in societal responses to environmental change. To build on our permafrost hazard risk maps, we are integrating economic principles and traditional land use elements. To assess economic implications of adaptation to permafrost change, we are working with geotechnical engineers to identify adaptation options (e.g., modified building techniques, permafrost thaw mitigation approaches) that suit the risks captured by our existing hazard risk maps. We layer this with an economic analysis of the costs associated with identified adaptation options, providing end-users with a more comprehensive basis upon which to make decisions related to infrastructure. NCE researchers have also integrated traditional land use activities in assessments of permafrost thaw risk, in a project led by Jean Marie River First Nation in the Northwest Territories. Here, the implications of permafrost degradation on food security and land use priorities were assessed by layering key game and gathering areas on permafrost thaw vulnerability maps. Results indicated that close to one quarter of big and small game habitats, and close to twenty percent of key furbearer and gathering areas within the First Nation

  4. Effect of permafrost on the formation of organic carbon pools and their physical-chemical properties in the Eastern Swiss Alps

    Science.gov (United States)

    Pichler, B.; Alewell, C.; Kneisel, C.; Meusburger, K.; Egli, M.

    2012-04-01

    Alpine soils contain a relatively large amount of organic matter (OM) even at elevations above the present-days timberline. Current climatic conditions and the occurrence of discontinuous and sporadic permafrost in the mountains result in a low turnover rate and therefore accumulation of OM. Alpine ecosystems are highly sensitive to environmental changes and therefore may become a potential source of atmospheric carbon dioxide (CO2) due to global warming. The expected changes in thermal and hydrological conditions in permafrost soils will not only influence OM degradation processes within the soil. Especially in alpine regions, soil erosion processes might be affected and potentially promote the mineralization of OM. However, the knowledge about the biogeochemistry and OM-stabilization processes and rates in permafrost soils in alpine regions is scarce, which makes it difficult to predict climate-carbon feedbacks. Our aim is to determine and compare the quantity, allocation and mean residence time of OM and the potential erosion processes in permafrost soils and adjacent unfrozen soils (distance between permafrost/non-permafrost soils max. 200m) at three locations in the Eastern Swiss Alps (Val Bever, Albula). Bulk soil, labile (oxidized by H2O2) and stable fractions (H2O2-resistant) were analyzed for their C-content and characterized using DRIFT (Diffuse Reflection Infrared Fourier Transform). Additionally, selected soil samples were 14C-dated. This approach has been applied for the first time in high alpine regions. To estimate the degree of disturbance, soil erosion has been qualitatively assessed by relating the OM-delta13C values of the soil profiles of interest to undisturbed reference profiles. We found rather well-developed soil profiles and a relatively high amount of OM at both types of sites (permafrost/non-permafrost), leading to the assumption that these soils developed over a certain period under a different (warmer) climate. This fact is supported by

  5. Evaporation and Degradation of a Sessile Droplet of VX on an Impermeable Surface

    Science.gov (United States)

    2017-09-01

    droplets are deposited on the surfaces of materials, they can spread, evaporate, and potentially absorb into the underlying material. Quantifying...Based on auxiliary chemical analysis performed in this work (Fourier transform infrared [ FTIR ] spectroscopy, vial reactor), it is believed that the...ATR accessory (Specac Golden Gate, diamond ATR crystal; Fort Washington, PA) and analyzed on a Thermo-Nicolet 670 FTIR spectrometer (Thermo Scientific

  6. Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites

    International Nuclear Information System (INIS)

    Xue Gang; Liu Huanhuan; Chen Quanyuan; Hills, Colin; Tyrer, Mark; Innocent, Francis

    2011-01-01

    A photocatalyst comprising nano-sized TiO 2 particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO 2 /GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO 2 immobilization. A 99.5% removal efficiency for HA from solution was achieved at an initial concentration of 15 mg/L in a period of 3 h. It was found that degradation of HA on the TiO 2 /GAC composite was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. The fitting of experimental results with the Langmuir-Hinshelwood (L-H) model showed that the reaction rate constant and the adsorption constant values were 0.1124 mg/(L min) and 0.3402 L/mg. The latter is 1.7 times of the calculated value by fitting the adsorption equilibrium data into the Langmuir equation.

  7. An oxygen-insensitive degradable resist for fabricating metallic patterns on highly curved surfaces by UV-nanoimprint lithography.

    Science.gov (United States)

    Hu, Xin; Huang, Shisong; Gu, Ronghua; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng

    2014-10-01

    In this paper, an oxygen-insensitive degradable resist for UV-nanoimprint is designed, com-prising a polycyclic degradable acrylate monomer, 2,10-diacryloyloxymethyl-1,4,9,12-tetraoxa-spiro [4.2.4.2] tetradecane (DAMTT), and a multifunctional thiol monomer pentaerythritol tetra(3-mercaptopropionate) (PETMP). The resist can be quickly UV-cured in the air atmosphere and achieve a high monomer conversion of over 98%, which greatly reduce the adhesion force between the resist and the soft mold. High conversion, in company with an adequate Young's modulus (about 1 GPa) and an extremely low shrinkage (1.34%), promises high nanoimprint resolution of sub-50 nm. The cross-linked resist is able to break into linear molecules in a hot acid solvent. As a result, metallic patterns are fabricated on highly curved surfaces via the lift off process without the assistance of a thermoplastic polymer layer. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Uncertainty in Arctic hydrology projections and the permafrost-carbon feedback

    Science.gov (United States)

    Andresen, C. G.; Lawrence, D. M.; Wilson, C. J.; McGuire, D.

    2017-12-01

    Projected warming is expected to thaw permafrost soils and deepen the permafrost active layer. These changes will affect surface hydrological conditions. Since the soil hydrologic state exerts a strong influence on the rate and pathway of soil organic matter decomposition into CO2 or CH4, there is a strong need to examine and better understand model projections of hydrologic change and how differences in process representation affect projections of wetting and/or drying of changing permafrost landscapes. This study aims to advance understanding of where, when and why arctic will become wetter or drier. We assessed simulations from 8 "permafrost enabled" land models that were run in offline mode from 1960 to 2299 forced with the same projected climate for a high-emissions scenario. Climate models project increased precipitation (P) across most of the Arctic domain and the land models indicate that runoff and evapotranspiration (ET) will also both increase. In general, the water input to the soil (P-ET) also increases, but the models project a contradicting long-term drying of the surface soil. The surface drying in the models can generally be explained by filtration of moisture to deeper soil layers as the active layer deepens or by increased sub-surface drainage where permafrost in a grid cell thaws completely. Though, there is a qualitative agreement in this type of response across the models, the projections vary dramatically in magnitude. Variability among simulations is largely attributed to parameterization and structural differences across the participating models, particularly the diverse representations of evapotranspiration, water table and soil water storage and transmission. A limited set of results from single forcing experiments suggests that the warming effect in the sensitivity analysis was the principal driver of soil drying while CO2 and precipitation effects had a small wetting influence. When compared to observational data, simulations tend to

  9. Data Integration Tool: Permafrost Data Debugging

    Science.gov (United States)

    Wilcox, H.; Schaefer, K. M.; Jafarov, E. E.; Pulsifer, P. L.; Strawhacker, C.; Yarmey, L.; Basak, R.

    2017-12-01

    We developed a Data Integration Tool (DIT) to significantly speed up the time of manual processing needed to translate inconsistent, scattered historical permafrost data into files ready to ingest directly into the Global Terrestrial Network-Permafrost (GTN-P). The United States National Science Foundation funded this project through the National Snow and Ice Data Center (NSIDC) with the GTN-P to improve permafrost data access and discovery. We leverage this data to support science research and policy decisions. DIT is a workflow manager that divides data preparation and analysis into a series of steps or operations called widgets (https://github.com/PermaData/DIT). Each widget does a specific operation, such as read, multiply by a constant, sort, plot, and write data. DIT allows the user to select and order the widgets as desired to meet their specific needs, incrementally interact with and evolve the widget workflows, and save those workflows for reproducibility. Taking ideas from visual programming found in the art and design domain, debugging and iterative design principles from software engineering, and the scientific data processing and analysis power of Fortran and Python it was written for interactive, iterative data manipulation, quality control, processing, and analysis of inconsistent data in an easily installable application. DIT was used to completely translate one dataset (133 sites) that was successfully added to GTN-P, nearly translate three datasets (270 sites), and is scheduled to translate 10 more datasets ( 1000 sites) from the legacy inactive site data holdings of the Frozen Ground Data Center (FGDC). Iterative development has provided the permafrost and wider scientific community with an extendable tool designed specifically for the iterative process of translating unruly data.

  10. Microbial Metabolism in Permafrost and Ice

    Science.gov (United States)

    Price, P. B.; Bramall, N.; Bay, R. C.

    2003-12-01

    Metabolic rates of microbial communities at low temperature have not been systematically studied, despite discoveries of microbes that survive with very little nutrient in ice, permafrost, and deep open-ocean sites, and despite interest in possible life on Mars and Europa. We investigated the temperature-dependence of growth rates kg, maintenance rates km, and survival rates ks, using existing data on kg(T) for permafrost bacteria, on km(T) using radiotracers, and on ks(T) using geochemical methods. Data were collected for temperatures from 28° C to -40° C. The rates for the three modes are consistent with a single activation energy U ≈ 100-110 kJ/mol, and they scale as kg(T):km(T):ks(T) ≈ 107:104:1. The rate ks(T) for survival of a dormant microbial community is found to be roughly that required solely for repairing molecular damage due to amino acid racemization + DNA depurination. We conclude that for living microbes the rate of molecular repair equals the rate of molecular damage. There is no indication of a threshold temperature for metabolism, at least down to -40° C. To assay microbial life in the coldest terrestrial environments (down to -55° C) and in future to search for present or past life on Mars, we have designed a miniaturized biospectral logger that will fit into a 4-cm borehole in ice, permafrost and rock. The logger will use side-directed laser beams at wavelengths 224 and 370 nm to detect autofluorescence of biomolecules and discriminate against mineral autofluorescence. Six channels will map fluorescence spectra and a seventh channel will measure light scattered from dust (in ice) or rock (in permafrost). Fluorescent biomolecules of interest include tryptophan, tyrosine, NADH, FAD, F420, chlorophyll, bacteriorhodopsin, porphyrins, pyoverdin, PAHs, humic acid, and fulvic acid. The logger will be able to detect microbial concentrations as low as 1 cell cm-3 in clean ice.

  11. Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

    Science.gov (United States)

    Vonk, J. E.; Tank, S. E.; Bowden, W. B.; Laurion, I.; Vincent, W. F.; Alekseychik, P.; Amyot, M.; Billet, M. F.; Canário, J.; Cory, R. M.; Deshpande, B. N.; Helbig, M.; Jammet, M.; Karlsson, J.; Larouche, J.; MacMillan, G.; Rautio, M.; Anthony, K. M. Walter; Wickland, K. P.

    2015-12-01

    The Arctic is a water-rich region, with freshwater systems covering about 16 % of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery

  12. Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

    Science.gov (United States)

    Vonk, J.E.; Tank, S.E.; Bowden, W.B.; Laurion, I.; Vincent, W.F.; Alekseychik, P.; Amyot, Y.; Billet, M.F.; Canario, J.; Cory, R.M.; Deshpande, B.N.; Helbig, M.; Jammet, M.; Karlsson, J.; Larouche, J.; MacMillan, G.; Rautio, Milla; Walter Anthony, K.M.; Wickland, Kimberly P.

    2015-01-01

    The Arctic is a water-rich region, with freshwater systems covering about 16 % of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery

  13. Landsat-based trend analysis of lake dynamics across northern permafrost regions

    Science.gov (United States)

    Nitze, Ingmar; Grosse, Guido; Jones, Benjamin M.; Arp, Christopher D.; Ulrich, Mathias; Federov, Alexander; Veremeeva, Alexandra

    2017-01-01

    Lakes are a ubiquitous landscape feature in northern permafrost regions. They have a strong impact on carbon, energy and water fluxes and can be quite responsive to climate change. The monitoring of lake change in northern high latitudes, at a sufficiently accurate spatial and temporal resolution, is crucial for understanding the underlying processes driving lake change. To date, lake change studies in permafrost regions were based on a variety of different sources, image acquisition periods and single snapshots, and localized analysis, which hinders the comparison of different regions. Here we present, a methodology based on machine-learning based classification of robust trends of multi-spectral indices of Landsat data (TM,ETM+, OLI) and object-based lake detection, to analyze and compare the individual, local and regional lake dynamics of four different study sites (Alaska North Slope, Western Alaska, Central Yakutia, Kolyma Lowland) in the northern permafrost zone from 1999 to 2014. Regional patterns of lake area change on the Alaska North Slope (-0.69%), Western Alaska (-2.82%), and Kolyma Lowland (-0.51%) largely include increases due to thermokarst lake expansion, but more dominant lake area losses due to catastrophic lake drainage events. In contrast, Central Yakutia showed a remarkable increase in lake area of 48.48%, likely resulting from warmer and wetter climate conditions over the latter half of the study period. Within all study regions, variability in lake dynamics was associated with differences in permafrost characteristics, landscape position (i.e. upland vs. lowland), and surface geology. With the global availability of Landsat data and a consistent methodology for processing the input data derived from robust trends of multi-spectral indices, we demonstrate a transferability, scalability and consistency of lake change analysis within the northern permafrost region.

  14. Comparison of algorithms and parameterisations for infiltration into organic-covered permafrost soils

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2010-05-01

    Full Text Available Infiltration into frozen and unfrozen soils is critical in hydrology, controlling active layer soil water dynamics and influencing runoff. Few Land Surface Models (LSMs and Hydrological Models (HMs have been developed, adapted or tested for frozen conditions and permafrost soils. Considering the vast geographical area influenced by freeze/thaw processes and permafrost, and the rapid environmental change observed worldwide in these regions, a need exists to improve models to better represent their hydrology.

    In this study, various infiltration algorithms and parameterisation methods, which are commonly employed in current LSMs and HMs were tested against detailed measurements at three sites in Canada's discontinuous permafrost region with organic soil depths ranging from 0.02 to 3 m. Field data from two consecutive years were used to calibrate and evaluate the infiltration algorithms and parameterisations. Important conclusions include: (1 the single most important factor that controls the infiltration at permafrost sites is ground thaw depth, (2 differences among the simulated infiltration by different algorithms and parameterisations were only found when the ground was frozen or during the initial fast thawing stages, but not after ground thaw reaches a critical depth of 15 to 30 cm, (3 despite similarities in simulated total infiltration after ground thaw reaches the critical depth, the choice of algorithm influenced the distribution of water among the soil layers, and (4 the ice impedance factor for hydraulic conductivity, which is commonly used in LSMs and HMs, may not be necessary once the water potential driven frozen soil parameterisation is employed. Results from this work provide guidelines that can be directly implemented in LSMs and HMs to improve their application in organic covered permafrost soils.

  15. Permafrost conditions in peatlands regulate magnitude, timing, and chemical composition of catchment dissolved organic carbon export.

    Science.gov (United States)

    Olefeldt, David; Roulet, Nigel T

    2014-10-01

    Permafrost thaw in peatlands has the potential to alter catchment export of dissolved organic carbon (DOC) and thus influence downstream aquatic C cycling. Subarctic peatlands are often mosaics of different peatland types, where permafrost conditions regulate the hydrological setting of each type. We show that hydrological setting is key to observed differences in magnitude, timing, and chemical composition of DOC export between permafrost and nonpermafrost peatland types, and that these differences influence the export of DOC of larger catchments even when peatlands are minor catchment components. In many aspects, DOC export from a studied peatland permafrost plateau was similar to that of a forested upland catchment. Similarities included low annual export (2-3 g C m(-2) ) dominated by the snow melt period (~70%), and how substantial DOC export following storms required wet antecedent conditions. Conversely, nonpermafrost fens had higher DOC export (7 g C m(-2) ), resulting from sustained hydrological connectivity during summer. Chemical composition of catchment DOC export arose from the mixing of highly aromatic DOC from organic soils from permafrost plateau soil water and upland forest surface horizons with nonaromatic DOC from mineral soil groundwater, but was further modulated by fens. Increasing aromaticity from fen inflow to outlet was substantial and depended on both water residence time and water temperature. The role of fens as catchment biogeochemical hotspots was further emphasized by their capacity for sulfate retention. As a result of fen characteristics, a 4% fen cover in a mixed catchment was responsible for 34% higher DOC export, 50% higher DOC concentrations and ~10% higher DOC aromaticity at the catchment outlet during summer compared to a nonpeatland upland catchment. Expansion of fens due to thaw thus has potential to influence landscape C cycling by increasing fen capacity to act as biogeochemical hotspots, amplifying aquatic C cycling, and

  16. Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia.

    Science.gov (United States)

    Vonk, J E; Sánchez-García, L; van Dongen, B E; Alling, V; Kosmach, D; Charkin, A; Semiletov, I P; Dudarev, O V; Shakhova, N; Roos, P; Eglinton, T I; Andersson, A; Gustafsson, O

    2012-09-06

    The future trajectory of greenhouse gas concentrations depends on interactions between climate and the biogeosphere. Thawing of Arctic permafrost could release significant amounts of carbon into the atmosphere in this century. Ancient Ice Complex deposits outcropping along the ~7,000-kilometre-long coastline of the East Siberian Arctic Shelf (ESAS), and associated shallow subsea permafrost, are two large pools of permafrost carbon, yet their vulnerabilities towards thawing and decomposition are largely unknown. Recent Arctic warming is stronger than has been predicted by several degrees, and is particularly pronounced over the coastal ESAS region. There is thus a pressing need to improve our understanding of the links between permafrost carbon and climate in this relatively inaccessible region. Here we show that extensive release of carbon from these Ice Complex deposits dominates (57 ± 2 per cent) the sedimentary carbon budget of the ESAS, the world’s largest continental shelf, overwhelming the marine and topsoil terrestrial components. Inverse modelling of the dual-carbon isotope composition of organic carbon accumulating in ESAS surface sediments, using Monte Carlo simulations to account for uncertainties, suggests that 44 ± 10 teragrams of old carbon is activated annually from Ice Complex permafrost, an order of magnitude more than has been suggested by previous studies. We estimate that about two-thirds (66 ± 16 per cent) of this old carbon escapes to the atmosphere as carbon dioxide, with the remainder being re-buried in shelf sediments. Thermal collapse and erosion of these carbon-rich Pleistocene coastline and seafloor deposits may accelerate with Arctic amplification of climate warming.

  17. Borehole temperatures from mountain permafrost monitoring, Mongolia, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — Location and description of some geocryological boreholes in Mongolia. Data include latitude, longitude, location, depth of permafrost top and bottom, and mean...

  18. Gas hydrates and permafrost in continental northern West Siberia; Gashydrate und Permafrost im kontinentalen noerdlichen Westsibirien

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, B. [Bundesanstalt fuer Geowissenschaften und Rohstoffe, Hannover (Germany); Braun, A.; Poelchau, H.S. [Forschungszentrum Juelich (Germany). Inst. fuer Erdoel und Organische Geochemie; Littke, R. [RWTH Aachen (Germany). Lehrstuhl fuer Geologie, Geochemie und Lagerstaetten des Erdoels und der Kohle

    1997-12-31

    The largest natural gas pool in the world is located in northern part of the West Siberian Basin. During the Quaternary this reservoir became overlaid with several hundreds of metres of permafrost. The pressure and temperature conditions prevailing under this permafrost zone have led to the development of gas hydrates. As far as is known today there is no genetic relationship between the formation of the gas pool and the development of gas hydrates. The present contribution deals with these questions in detail. (MSK) [Deutsch] Im Nordteil des westsibirischen Beckens liegt die groesste Erdgaslagerstaette der Erde. Darueber hat sich im Quartaer ein mehrere hundert Meter maechtiger Permafrost gebildet. Die unter der Premafrostzone herrschenden Druck-und Temperaturbedingungen ermoeglichten die Bildung von Gashydraten. Nach heutigen Erkenntnisse besteht kein genetischer Zusammenhang zwischen Lagerstaettenbildung und Gashydraten. Im Folgenden werden Einzelheiten geschildert.

  19. Borehole permafrost data, Kumtor and Taragai Valleys, Tienshan, Kazakhstan, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset includes observations of the permafrost temperatures in the Inner Tien Shan were started in 1986 by Kazakhstan Alpine Permafrost Laboratory....

  20. Seasonal dynamics of permafrost carbon emissions: A passive, quasi-continuous 14CO2 sampler

    Science.gov (United States)

    Pedron, S.; Xu, X.; Walker, J. C.; Welker, J. M.; Klein, E. S.; Euskirchen, E. S.; Czimczik, C. I.

    2017-12-01

    Millennia of carbon (C) fixation by tundra vegetation, coupled with low rates of C mineralization by soil microorganisms and preservation in permafrost, have allowed Arctic soils to accumulate vast quantities of organic C (1672 Pg C total). Today, the Arctic is rapidly warming (0.48oC decade-1) and widespread degradation of permafrost may subject permafrost C to microbial mineralization and fluxes to the atmosphere, accelerating climate change. Loss of permafrost C can be quantified in situ by measuring the radiocarbon (14C) content of soil and ecosystem respiration, because permafrost C is older (depleted in 14C) than current plant products and soil C cycling operates on timescales of years to centuries. Here, we use 14C analysis of CO2 respired from graminoid tundra in Arctic Alaska to 1) apportion how plant and microbial respiration contribute to ecosystem respiration in spring, summer, and fall, and 2) elucidate the C sources of microbial respiration throughout the year. We used a novel, passive sampling system, capable of trapping diffusive CO2 throughout the active layer of tussock sedge tundra (n=4, from mineral soil to air) over periods of 2 days to 3 weeks in June 2017. CO2 was collected into various sizes of canisters, ranging from 0.5-32 L, and analyzed for its 14C content at UC Irvine's KCCAMS laboratory. To evaluate the system's efficiency, and quantify the temporal and spatial variability of ecosystem respiration sources, we co-deployed 3 Vaisala Carbocap [CO2] and temperature probes, and traditional chambers (n=6) and gas wells (n=10) for sampling of ecosystem- and soil-respired 14CO2 over 15 min-24 hours. A comparison of traditional methods with our new sampler indicates that the system accurately sampled the expected [CO2] depth gradient. The CO2 sampling rate was positively correlated to soil [CO2] (R2=0.963), equivalent to 1.4*10-3±1.6*10-3 mg C/L/month/ppm (n=8). Gas well and probe concentrations were of the same order of magnitude on the same

  1. Degradation of hydrocarbons in arctic areas

    International Nuclear Information System (INIS)

    Hundahl Pedersen, M.; Grau-Hansen, B.; Watson Nielsen, T.; Jensen, L.

    1999-12-01

    The scope of this project is to examine the natural degradation of a hydrocarbon contamination by investigating a specific location. The investigated location is a former airfield at Marraq situated on the west coast of Greenland, approx. 90 km south of Nuuk. In Autumn 1942 the US Air force established a diversion airfield called 'Teague Airfield' - under the military code name Bluie West-4. However, the location was abandoned in 1948 and accordingly all facilities and equipment were left behind, among these were a large amount of oil barrels, which mainly contained gas oil. In relation to the present investigation a number of disposal sites were found each containing approx. 50-600 oil barrels of 200 litres each. Through the years these barrels have corroded causing a heavy gas oil contamination several places on the site. This contamination is estimated to have taken place for approx. 40-50 years ago. The contamination is of such a severe character that a heavy smell of oil can be determined on site. Furthermore, vegetation mortality was observed around the barrels in connection to disposal sites situated in places covered by plants. Marraq is a peninsula consisting of coarse fluviatile deposits. The geology is relatively homogeneous without permafrost, which combined with a range of local defined contaminations, provide a unique possibility to assess the controlling environmental factors of natural degradation of oil contamination in the Arctic. A conservative estimate of the complete amount of gas oil which has contaminated the location is estimated to approx. 120,000 litres or more. The investigation showed that the extent of the oil degradation was different at the individual deposit sites. Roughly estimated the contamination is degraded on the order of 15 to twice the original oil amount. Assumable the contamination has been degraded due to the weathering process (evaporation and wash-out) and microbial degradation. Complex processes are involved depending

  2. Wetland succession in a permafrost collapse: interactions between fire and thermokarst

    Directory of Open Access Journals (Sweden)

    I. H. Myers-Smith

    2008-09-01

    Full Text Available To determine the influence of fire and thermokarst in a boreal landscape, we investigated peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate ~600 years of vegetation succession with a transition from a terrestrial forest to a sedge-dominated wetland over 100 years ago, and to a Sphagnum-dominated peatland in approximately 1970. The shift from sedge to Sphagnum, and a decrease in the detrended tree-ring width index of black spruce trees adjacent to the collapse coincided with an increase in the growing season temperature record from Fairbanks. This concurrent wetland succession and reduced growth of black spruce trees indicates a step-wise ecosystem-level response to a change in regional climate. In 2001, fire was observed coincident with permafrost collapse and resulted in lateral expansion of the peatland. These observations and the peat profile suggest that future warming and/or increased fire disturbance could promote permafrost degradation, peatland expansion, and increase carbon storage across this landscape; however, the development of drought conditions could reduce the success of both black spruce and Sphagnum, and potentially decrease the long-term ecosystem carbon storage.

  3. Permafrost detection in the headwalls of receding glaciers at the Dachstein Massif, Northern Calcareous Alps, Austria

    Science.gov (United States)

    Rode, Matthias; Gitschthaler, Christoph; Schnepfleitner, Harald; Kellerer-Pirklbauer, Andreas; Sass, Oliver

    2014-05-01

    sites. Interestingly, bedrock permafrost was also detected at an immediate glacier margin which has been ice-free for 2-3 decades at maximum. Possibly the glacier at this site was too thin to have a sufficient insulating effect on the rock and hence was cold-based in this position. Alternatively permafrost aggradation occurred rapidly in the few last decades at this site. A new and innovative method in geomorphology and permafrost research is the use of infrared photography. By using this method the gaps between the punctual temperature sensors and the profile lines of the geoelectric measurements can get closed. By using infrared photography it was possible to visualize patterns and amplitudes of the diurnal variations of the surface temperature. First results showed a faster and deeper cooling of the permafrost areas compared to non-permafrost rocks, which is in accordance with the BTS and ERT data.

  4. Climate hazards caused by thawing permafrost? Background information of the Federal Environmental Agency; Klimagefahr durch tauenden Permafrost? UBA-Hintergrundpapier

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-08-15

    The thawing of permafrost regions is supposed to increase climatic change processes due to the released methane. During the last decades the temperature of permafrost soils has increased by several tenths of degree up to 2 deg C. It is supposed that 10 to 20% of the permafrost regions will thaw during the next 100 years. The southern boundary of the permafrost region will move several hundred kilometers toward the north. Besides the increased risk for the climate system there will also be disadvantageous consequences for the ecosystems. Negative economic consequences are already observed and will be enhanced in the futures with significant cost for the public.

  5. Numerical simulations of permafrost dynamics in the source area of the Yellow River, central-eastern Qinghai-Tibet Plateau

    Science.gov (United States)

    Luo, D.; Marchenko, S. S.; Jin, H.; Romanovsky, V. E.

    2017-12-01

    Elevational permafrost on the Qinghai-Tibet Plateau (QTP) are particularly warm with more than half boreholes owning ground temperatures within -1 and 0 °C, therefore presumably sensitive to climate changes and anthropogenic activities. In the context of more serious climatic warming on the QTP than the global average, deterioration to ecology and damages to engineering projects in permafrost region had been frequently reported. To forecast further degradation of permafrost in the coming decades or centuries, a number of empirical or physical models have been implemented to study it. However, few attentions had been paid to variations of permafrost for the past century. In this study, we utilized the Geophysical Institute Permafrost (GIPL) model to simulate permafrost variations from 1901 to 2015 in the source area of the Yellow River, central-eastern QTP. Monthly air temperatures and precipitation from the CRU TS 4.0 datasets in 1901-2015 were employed as the input upper boundary conditions. Thermo-physical properties and moisture content of subsurface soils collected from the fieldwork and in situ measurements of ground temperatures were employed as initial conditions. An empirical estimated geothermal heat flux for each grid point was applied for the lower boundary conditions. Monthly air temperatures of 1901 were repeated for 50 times to drive the model to obtain thermal equilibrium, and then the measured ground temperatures were utilized to calibrate the soil properties. Results showed that, the mean annual air temperature (MAAT) did not dramatically change by a rate of consistently continuous increasing, but by rates of 0.27 °C·(10a)-1 in 1901-1944, -0.19 °C·(10a)-1 in 1945-1983, and 0.18°C·(10a)-1 in 1984-2015, while the overall trend was 0.02 °C·(10a)-1. During the past centennial periods, variations of permafrost temperatures at different depths resembled the fluctuation of air temperature with an attenuation effect downwards. During the period of

  6. Characterization of Drain Surface Water: Environmental Profile, Degradation Level and Geo-statistic Monitoring

    Directory of Open Access Journals (Sweden)

    Muhammad Waseem Mumtaz

    2015-12-01

    Full Text Available The physico-chemical characterization of the surface water. Samples was carried out collected from nine sampling points of drain passing by the territory of Hafizabad city, Punjab, Pakistan. The water of drain is used by farmers for irrigation purposes in nearby agricultural fields. Twenty water quality parameters were evaluated in three turns and the results obtained were compared with the National Environmental Quality Standards (NEQS municipal and industrial effluents prescribed limits. The highly significant difference (p0.05 was noted for temperature, pH, electrical conductivity, hardness, calcium, sodium, chemical oxygen demand and chloride among water samples from different sampling points. Furthermore, the experimental results of different water quality parameters studied at nine sampling points of the drain were used and interpolated in ArcGIS 9.3 environment system using kriging techniques to obtain calculated values for the remaining locations of the Drain.

  7. Baseline characteristics of climate, permafrost and land cover from a new permafrost observatory in the Lena River Delta, Siberia (1998–2011

    Directory of Open Access Journals (Sweden)

    J. Boike

    2013-03-01

    Full Text Available Samoylov Island is centrally located within the Lena River Delta at 72° N, 126° E and lies within the Siberian zone of continuous permafrost. The landscape on Samoylov Island consists mainly of late Holocene river terraces with polygonal tundra, ponds and lakes, and an active floodplain. The island has been the focus of numerous multidisciplinary studies since 1993, which have focused on climate, land cover, ecology, hydrology, permafrost and limnology. This paper aims to provide a framework for future studies by describing the characteristics of the island's meteorological parameters (temperature, radiation and snow cover, soil temperature, and soil moisture. The land surface characteristics have been described using high resolution aerial images in combination with data from ground-based observations. Of note is that deeper permafrost temperatures have increased between 0.3 to 1.3 °C over the last five years. However, no clear warming of air and active layer temperatures is detected since 1998, though winter air temperatures during recent years have not been as cold as in earlier years. Data related to this article are archived under: http://doi. pangaea.de/10.1594/PANGAEA.806233 .

  8. Four years of UAS Imagery Reveals Vegetation Change Due to Permafrost Thaw

    Science.gov (United States)

    DelGreco, J. L.; Herrick, C.; Varner, R. K.; McArthur, K. J.; McCalley, C. K.; Garnello, A.; Finnell, D.; Anderson, S. M.; Crill, P. M.; Palace, M. W.

    2017-12-01

    Warming trends in sub-arctic regions have resulted in thawing of permafrost which in turn induces change in vegetation across peatlands. Collapse of palsas (i.e. permafrost plateaus) has also been correlated to increases in methane (CH4) emissions to the atmosphere. Vegetation change provides new microenvironments that promote CH4 production and emission, specifically through plant interactions and structure. By quantifying the changes in vegetation at the landscape scale, we will be able to understand the impact of thaw on CH4 emissions in these complex and climate sensitive northern ecosystems. We combine field-based measurements of vegetation composition and high resolution Unmanned Aerial Systems (UAS) imagery to characterize vegetation change in a sub-arctic mire. At Stordalen Mire (1 km x 0.5 km), Abisko, Sweden, we flew a fixed-wing UAS in July of each year between 2014 and 2017. High precision GPS ground control points were used to georeference the imagery. Seventy-five randomized square-meter plots were measured for vegetation composition and individually classified into one of five cover types, each representing a different stage of permafrost degradation. With this training data, each year of imagery was classified by cover type. The developed cover type maps were also used to estimate CH4 emissions across the mire based on average flux CH4 rates from each cover type obtained from flux chamber measurements collected at the mire. This four year comparison of vegetation cover and methane emissions has indicated a rapid response to permafrost thaw and changes in emissions. Estimation of vegetation cover types is vital in our understanding of the evolution of northern peatlands and its future role in the global carbon cycle.

  9. Reducing uncertainty in methane emission estimates from permafrost peatlands

    Science.gov (United States)

    Christensen, Torben R.

    2016-04-01

    surface waters, storms trigger emissions in the East Siberian Sea Shelf. Shallow lakes formed when permafrost thaws can belch methane from decomposing old organic deposits, of which there are huge amounts in the Arctic. All of these potentially important emissions are of a scale that still is in need of being reconciled with the atmospheric record. This presentation will give an overview of our current understanding of how methane emissions from northern natural environments influences the atmosphere and in turn the climate.

  10. Vegetation controls on carbon, water, and energy dynamics with implications for permafrost thaw

    Science.gov (United States)

    Loranty, M. M.; Berner, L. T.

    2013-12-01

    Changes in ecosystem structure and function characterized by climate induced alterations in vegetation communities will exert strong influence on the fate of permafrost carbon via controls on surface energy partitioning. These controls are likely to occur both directly through changes in ground heat fluxes and indirectly through climate feedbacks associated with changes in albedo and evapotranspiration. Larch forests of northeastern Siberia constitute the largest ecosystem type underlain by continuous permafrost and therefore warrant considerable attention in this regard. Here we report observations of carbon, water, and energy fluxes made using the static chamber method for three understory vegetation communities in a mature northeastern Siberian larch forest. We find that carbon and water fluxes tend to increase in magnitude with NDVI, with carbon fluxes exhibiting net uptake during the growing season in vegetation communities dominated by deciduous shrubs. Communities characterized by a combination of evergreen and deciduous shrubs and mosses, or by lichens we find lower water fluxes and carbon neutrality. In the case of lichens, water fluxes are low while surface and soil temperatures as well as thaw depths are relatively high. These results illustrate the potential for vegetation to influence permafrost dynamics through controls on surface energy partitioning. While our results stem from a relatively small spatial scale, they are a relevant analog for large-scale shifts in arctic and boreal vegetation communities as well as changes in successional dynamics associated with changing disturbance regimes, particularly fire.

  11. Strong degradation of palsas and peat plateaus in northern Norway during the last 60 years

    Directory of Open Access Journals (Sweden)

    A. F. Borge

    2017-01-01

    vegetation, wildlife, hydrology and carbon cycle. Firstly, we have systematically mapped the occurrence of palsas and peat plateaus in the northernmost county of Norway (Finnmark, ∼ 50 000 km2 by manual interpretation of aerial images from 2005 to 2014 at a spatial resolution of 250 m. At this resolution, mires and wetlands with palsas or peat plateaus occur in about 850 km2 of Finnmark, with the actual palsas and peat plateaus underlain by permafrost covering a surface area of approximately 110 km2. Secondly, we have quantified the lateral changes of the extent of palsas and peat plateaus for four study areas located along a NW–SE transect through Finnmark by utilizing repeat aerial imagery from the 1950s to the 2010s. The results of the lateral changes reveal a total decrease of 33–71 % in the areal extent of palsas and peat plateaus during the study period, with the largest lateral change rates observed in the last decade. However, the results indicate that degradation of palsas and peat plateaus in northern Norway has been a consistent process during the second half of the 20th century and possibly even earlier. Significant rates of areal change are observed in all investigated time periods since the 1950s, and thermokarst landforms observed on aerial images from the 1950s suggest that lateral degradation was already an ongoing process at this time. The results of this study show that lateral erosion of palsas and peat plateaus is an important pathway for permafrost degradation in the sporadic permafrost zone in northern Scandinavia. While the environmental factors governing the rate of erosion are not yet fully understood, we note a moderate increase in air temperature, precipitation and snow depth during the last few decades in the region.

  12. Modelling the temperature evolution of permafrost and seasonal frost in southern Norway during the 20th and 21st century

    Science.gov (United States)

    Hipp, T.; Etzelmüller, B.; Farbrot, H.; Schuler, T. V.

    2011-03-01

    A heat flow model was used to simulate both past and future ground temperatures of mountain permafrost in Southern Norway. A reconstructed air temperature series back to 1860 was used to evaluate the permafrost evolution since the end of the Little Ice Age in the region. The impact of a changing climate on discontinuous mountain permafrost until 2100 is predicted by using downscaled temperatures from an ensemble of downscaled climate models for the A1B scenario. From 13 borehole locations two consecutive years of ground temperature, air temperature and snow cover data are available for model calibration and validation. The boreholes are located at different elevations and in substrates having different thermal properties. With an increase of air temperature of ~+1.5 °C over 1860-2010 and an additional warming of +2.8 °C towards 2100 in air temperature, we simulate the evolution of ground temperatures for the borehole locations. According to model results, the active-layer thickness has increased since 1860 by about 0.5-5 m and >10 m for the sites Juvvass and Tron, respectively. The simulations also suggest that at an elevation of about 1900 m a.s.l. permafrost will degrade until the end of this century with a likelihood of 55-75% given the chosen A1B scenario.

  13. In situ QCM and TM-AFM investigations of the early stages of degradation of silver and copper surfaces

    International Nuclear Information System (INIS)

    Kleber, Ch.; Hilfrich, U.; Schreiner, M.

    2007-01-01

    The early stages of atmospheric corrosion of pure copper and pure silver specimens were investigated performing in situ tapping mode atomic force microscopy (TM-AFM), in situ quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS). The information obtained by TM-AFM is the change of the topography of the sample surfaces with emphasis on the shape and lateral distribution of the corrosion products grown within the first hours of weathering. The simultaneously performed in situ QCM measurements are indicating the mass changes due to possibly occurring corrosive processes on the surface during weathering and are therefore a valuable tool for the determination of corrosion rates. Investigations were carried out in synthetic air at different levels of relative humidity (RH) with and without addition of 250 ppb SO 2 as acidifying agent. On a polished copper surface the growth of corrosion products could be observed by TM-AFM analysis at 60% RH without any addition of acidifying gases [M. Wadsak, M. Schreiner, T. Aastrup, C. Leygraf, Surf. Sci. 454-456 (2000) 246-250]. On a weathered copper surface the addition of SO 2 to the moist air stream leads to the formation of additional features as already described in the literature [M. Wadsak, M. Schreiner, T. Aastrup, C. Leygraf, Surf. Sci. 454-456 (2000) 246-250; Ch. Kleber, J. Weissenrieder, M. Schreiner, C. Leygraf, Appl. Surf. Sci. 193 (2002) 245-253]. Exposing a silver specimen to humidity leads to the degradation of the surface structure as well as to a formation of corrosion products, which could be detected by in situ QCM measurements. After addition of 250 ppb SO 2 to the moist gas stream an increase of the formed feature's volume on the silver surface could be observed by TM-AFM measurements. The results obtained additionally from the in situ QCM measurements confirm the influence of SO 2 due to a further increase of the mass of the formed corrosion layer (and therefore an increase of the

  14. Characterization of ice Content in Permafrost Soils on the Seward Peninsula, Alaska Using Induced Polarization

    Science.gov (United States)

    Nolan, J.; Parsekian, A.; Slater, L.; Plug, L.; Grosse, G.; Walter, K.

    2008-12-01

    Zones of high ice content are imaged using direct current (DC) and induced polarization (IP) electrical measurements in Permafrost soils on the Northern Seward Peninsula. Variable ice content in near surface permafrost as a result of ice wedge development is a major control on thermokarst erosion rates, making the characterization of distribution important to process modeling. A set of IP and DC resistivity measurements were collected at five locations, four in varying generations of thermokarst lake basins and one where there is no evidence of thermokarst lake basin development. GPR data was also collected using 100 and 200 mHz unsheilded antenna at each line, as well as high precision DGPS measurements, vegetation mapping, active layer thickness measurements, and soil characterization using test pits and nearby outcrops. DC resistivity and GPR results correspond well to the active layer probe and test pits dug to the bottom of the active layer. IP imaging shows the location of elevated ice content as strongly nonpolarizable anomolies which correlate to ice wedge ridges measured with GPS and observed from vegetation patterning. Non-polarizable targets found deeper in the permefrost at the site not yet effected by thermokarst erosion indicates that Pleistocene aged ice wedges are below the Holocene ice wedges expressed at the surface as distinct patterning, confirming that ice content distribution may not be easily estimated from surface patterning alone. These observations are confirmed by nearby exposures of ice wedges. The results show that the IP measurements are useful for characterizing ice content distribution in permafrost soils may be used to link ground based observations with larger scale estimates that are needed for process and carbon balance modeling of permafrost soils.

  15. Magnetic loading of TiO2/SiO2/Fe3O4 nanoparticles on electrode surface for photoelectrocatalytic degradation of diclofenac

    International Nuclear Information System (INIS)

    Hu, Xinyue; Yang, Juan; Zhang, Jingdong

    2011-01-01

    Highlights: ► Magnetic TSF nanoparticles are immobilized on electrode surface with aid of magnet. ► Magnetically attached TSF electrode shows high photoelectrochemical activity. ► Diclofenac is effectively degraded on TSF-loaded electrode by photoelectrocatalysis. ► Photoelectrocatalytic degradation of diclofenac is monitored with voltammetry. - Abstract: A novel magnetic nanomaterials-loaded electrode developed for photoelectrocatalytic (PEC) treatment of pollutants was described. Prior to electrode fabrication, magnetic TiO 2 /SiO 2 /Fe 3 O 4 (TSF) nanoparticles were synthesized and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and FT-IR measurements. The nanoparticles were dispersed in ethanol and then immobilized on a graphite electrode surface with aid of magnet to obtain a TSF-loaded electrode with high photoelectrochemical activity. The performance of the TSF-loaded electrode was tested by comparing the PEC degradation of methylene blue in the presence and absence of magnet. The magnetically attached TSF electrode showed higher PEC degradation efficiency with desirable stability. Such a TSF-loaded electrode was applied to PEC degradation of diclofenac. After 45 min PEC treatment, 95.3% of diclofenac was degraded on the magnetically attached TSF electrode.

  16. Preparation of nitrogen-doped cotton stalk microporous activated carbon fiber electrodes with different surface area from hexamethylenetetramine-modified cotton stalk for electrochemical degradation of methylene blue

    Science.gov (United States)

    Li, Kunquan; Rong, Zhang; Li, Ye; Li, Cheng; Zheng, Zheng

    Cotton-stalk activated carbon fibers (CSCFs) with controllable micropore area and nitrogen content were prepared as an efficient electrode from hexamethylenetetramine-modified cotton stalk by steam/ammonia activation. The influence of microporous area, nitrogen content, voltage and initial concentration on the electrical degradation efficiency of methylene blue (MB) was evaluated by using CSCFs as anode. Results showed that the CSCF electrodes exhibited excellent MB electrochemical degradation ability including decolorization and COD removal. Increasing micropore surface area and nitrogen content of CSCF anode leaded to a corresponding increase in MB removal. The prepared CSCF-800-15-N, which has highest N content but lowest microporous area, attained the best degradation effect with 97% MB decolorization ratio for 5 mg/L MB at 12 V in 4 h, implying the doped nitrogen played a prominent role in improving the electrochemical degradation ability. The electrical degradation reaction was well described by first-order kinetics model. Overall, the aforesaid findings suggested that the nitrogen-doped CSCFs were potential electrode materials, and their electrical degradation abilities could be effectively enhanced by controlling the nitrogen content and micropore surface area.

  17. Is the ancient permafrost bacteria able to keep DNA stable?

    Indian Academy of Sciences (India)

    Navya

    According to the preliminary DNA analysis, bacterial cells collected from the relict permafrost appeared to be Bacillus sp. strains, which are close to modern bacteria at a molecular level. Therefore, a number of question raises. For example, are isolated bacteria as old as the permafrost itself or could contamination with more ...

  18. Contribution of permafrost soils to the global carbon budget

    International Nuclear Information System (INIS)

    Schaphoff, Sibyll; Heyder, Ursula; Ostberg, Sebastian; Gerten, Dieter; Heinke, Jens; Lucht, Wolfgang

    2013-01-01

    Climate warming affects permafrost soil carbon pools in two opposing ways: enhanced vegetation growth leads to higher carbon inputs to the soil, whereas permafrost melting accelerates decomposition and hence carbon release. Here, we study the spatial and temporal dynamics of these two processes under scenarios of climate change and evaluate their influence on the carbon balance of the permafrost zone. We use the dynamic global vegetation model LPJmL, which simulates plant physiological and ecological processes and includes a newly developed discrete layer energy balance permafrost module and a vertical carbon distribution within the soil layer. The model is able to reproduce the interactions between vegetation and soil carbon dynamics as well as to simulate dynamic permafrost changes resulting from changes in the climate. We find that vegetation responds more rapidly to warming of the permafrost zone than soil carbon pools due to long time lags in permafrost thawing, and that the initial simulated net uptake of carbon may continue for some decades of warming. However, once the turning point is reached, if carbon release exceeds uptake, carbon is lost irreversibly from the system and cannot be compensated for by increasing vegetation carbon input. Our analysis highlights the importance of including dynamic vegetation and long-term responses into analyses of permafrost zone carbon budgets. (letter)

  19. Using Measurements of Topography to Infer Rates of Crater Degradation and Surface Evolution on the Moon and Mercury

    Science.gov (United States)

    Fassett, C.; Crowley, M. C.; Leight, C.; Dyar, M. D.; Minton, D.; Hirabayashi, M.; Thomson, B. J.; Watters, W. A.

    2017-12-01

    Observations of how the topography of impact craters vary with age enable estimates for how fast the surface of airless bodies evolve. Fresh simple craters form with a depth/diameter (d/D) ratio of 0.21, sharp rims, and steep interior slopes. These fresh craters then are eroded and infilled, reducing d/D, and topographically muting their appearance. On the Moon and Mercury, the dominant mechanism responsible for this erosion likely includes the cumulative effects of numerous later small primary and secondary impact craters. The resulting topographic evolution can be modeled as a diffusive process, similar to how hillslopes evolve on Earth. However, the topographic diffusivity (κ) forced by impact cratering is dependent on both scale and time, so diffusion is anomalous, rather than classical. A key finding of this study is how the diffusivity and hence erosion rate is different on the Moon and Mercury. On the Moon, based on measurements of >13000 craters in the 800 m ≤ D ≤ 5 km size range on the lunar maria, the average diffusivity at 1 km scale is estimated as 5.5m2/Myr. With this diffusivity, D 1 km craters are reduced to 52% of their original depth over 3 Ga. Larger craters have relative depths that are much less reduced over an equivalent period, and smaller craters are much more eroded, even accounting for some scale-dependence of diffusivity (κ ∝ D0.9). In fact, the smallest craters are sufficiently degraded to become unrecognizable. The rate of topographic diffusion is the critical control on how a crater population reaches saturation equilibrium. On Mercury, d/D for 204 craters with 2.5 km ≤ D ≤ 5 km on the smooth plains were measured with MDIS stereo topography and MLA data. For these craters, the median d/D was 0.13. Craters in this same size range on the lunar maria are much less modified than those on Mercury when measured with the same techniques on data resampled to a resolution equivalent to the Mercury data, and their d/D is nearly

  20. Formation of environmentally persistent free radicals as the mechanism for reduced catechol degradation on hematite-silica surface under UV irradiation.

    Science.gov (United States)

    Li, Hao; Pan, Bo; Liao, Shaohua; Zhang, Di; Xing, Baoshan

    2014-05-01

    Iron is rich in soils, and is recently reported to form stable complexes with organic free radicals, generating environmentally persistent free radicals (EPFRs). The observation may challenge the common viewpoint that iron is an effective catalyst to facilitate the degradation of various organic chemicals. But no study was specifically designed to investigate the possible inhibited degradation of organic chemicals because of the formation of EPFRs in dry environment. We observed that catechol degradation under UV irradiation was decreased over 20% in silica particles coated with 1% hematite in comparison to uncoated silica particles. Stabilized semiquinone or quinine and phenol radicals were involved in HMT-silica system. EPFR formation was thus the reason for the reduced catechol degradation on HMT-silica surface under UV irradiation at ambient temperature. EPFRs should be incorporated in the studies of organic contaminants geochemical behavior, and will be a new input in their environmental fate modeling. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Palaeoclimate characteristics in interior Siberia of MIS 6-2: first insights from the Batagay permafrost mega-thaw slump in the Yana Highlands

    Science.gov (United States)

    Ashastina, Kseniia; Schirrmeister, Lutz; Fuchs, Margret; Kienast, Frank

    2017-07-01

    Syngenetic permafrost deposits formed extensively on and around the arising Beringian subcontinent during the Late Pleistocene sea level lowstands. Syngenetic deposition implies that all material, both mineral and organic, freezes parallel to sedimentation and remains frozen until degradation of the permafrost. Permafrost is therefore a unique archive of Late Pleistocene palaeoclimate. Most studied permafrost outcrops are situated in the coastal lowlands of northeastern Siberia; inland sections are, however, scarcely available. Here, we describe the stratigraphical, cryolithological, and geochronological characteristics of a permafrost sequence near Batagay in the Siberian Yana Highlands, the interior of the Sakha Republic (Yakutia), Russia, with focus on the Late Pleistocene Yedoma ice complex (YIC). The recently formed Batagay mega-thaw slump exposes permafrost deposits to a depth of up to 80 m and gives insight into a climate record close to Verkhoyansk, which has the most severe continental climate in the Northern Hemisphere. Geochronological dating (optically stimulated luminescence, OSL, and 14C ages) and stratigraphic implications delivered a temporal frame from the Middle Pleistocene to the Holocene for our sedimentological interpretations and also revealed interruptions in the deposition. The sequence of lithological units indicates a succession of several distinct climate phases: a Middle Pleistocene ice complex indicates cold stage climate. Then, ice wedge growth stopped due to highly increased sedimentation rates and eventually a rise in temperature. Full interglacial climate conditions existed during accumulation of an organic-rich layer - plant macrofossils reflected open forest vegetation existing under dry conditions during Marine Isotope Stage (MIS) 5e. The Late Pleistocene YIC (MIS 4-MIS 2) suggests severe cold-stage climate conditions. No alas deposits, potentially indicating thermokarst processes, were detected at the site. A detailed comparison

  2. Palaeoclimate characteristics in interior Siberia of MIS 6–2: first insights from the Batagay permafrost mega-thaw slump in the Yana Highlands

    Directory of Open Access Journals (Sweden)

    K. Ashastina

    2017-07-01

    Full Text Available Syngenetic permafrost deposits formed extensively on and around the arising Beringian subcontinent during the Late Pleistocene sea level lowstands. Syngenetic deposition implies that all material, both mineral and organic, freezes parallel to sedimentation and remains frozen until degradation of the permafrost. Permafrost is therefore a unique archive of Late Pleistocene palaeoclimate. Most studied permafrost outcrops are situated in the coastal lowlands of northeastern Siberia; inland sections are, however, scarcely available. Here, we describe the stratigraphical, cryolithological, and geochronological characteristics of a permafrost sequence near Batagay in the Siberian Yana Highlands, the interior of the Sakha Republic (Yakutia, Russia, with focus on the Late Pleistocene Yedoma ice complex (YIC. The recently formed Batagay mega-thaw slump exposes permafrost deposits to a depth of up to 80 m and gives insight into a climate record close to Verkhoyansk, which has the most severe continental climate in the Northern Hemisphere. Geochronological dating (optically stimulated luminescence, OSL, and 14C ages and stratigraphic implications delivered a temporal frame from the Middle Pleistocene to the Holocene for our sedimentological interpretations and also revealed interruptions in the deposition. The sequence of lithological units indicates a succession of several distinct climate phases: a Middle Pleistocene ice complex indicates cold stage climate. Then, ice wedge growth stopped due to highly increased sedimentation rates and eventually a rise in temperature. Full interglacial climate conditions existed during accumulation of an organic-rich layer – plant macrofossils reflected open forest vegetation existing under dry conditions during Marine Isotope Stage (MIS 5e. The Late Pleistocene YIC (MIS 4–MIS 2 suggests severe cold-stage climate conditions. No alas deposits, potentially indicating thermokarst processes, were detected at the

  3. Direct detection of additives and degradation products from polymers by liquid extraction surface analysis employing chip-based nanospray mass spectrometry.

    Science.gov (United States)

    Paine, Martin R L; Barker, Philip J; Maclauglin, Shane A; Mitchell, Todd W; Blanksby, Stephen J

    2012-02-29

    Polymer-based surface coatings in outdoor applications experience accelerated degradation due to exposure to solar radiation, oxygen and atmospheric pollutants. These deleterious agents cause undesirable changes to the aesthetic and mechanical properties of the polymer, reducing its lifetime. The use of antioxidants such as hindered amine light stabilisers (HALS) retards these degradative processes; however, mechanisms for HALS action and polymer degradation are poorly understood. Detection of the HALS TINUVIN®123 (bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate) and the polymer degradation products directly from a polyester-based coil coating was achieved by liquid extraction surface analysis (LESA) coupled to a triple quadrupole QTRAP® 5500 mass spectrometer. The detection of TINUVIN®123 and melamine was confirmed by the characteristic fragmentation pattern observed in LESA-MS/MS spectra that was identical to that reported for authentic samples. Analysis of an unstabilised coil coating by LESA-MS after exposure to 4 years of outdoor field testing revealed the presence of melamine (1,3,5-triazine-2,4,6-triamine) as a polymer degradation product at elevated levels. Changes to the physical appearance of the coil coating, including powder-like deposits on the coating's surface, were observed to coincide with melamine deposits and are indicative of the phenomenon known as polymer 'blooming'. For the first time, in situ detection of analytes from a thermoset polymer coating was accomplished without any sample preparation, providing advantages over traditional extraction-analysis approaches and some contemporary ambient MS methods. Detection of HALS and polymer degradation products such as melamine provides insight into the mechanisms by which degradation occurs and suggests LESA-MS is a powerful new tool for polymer analysis. Copyright © 2012 John Wiley & Sons, Ltd.

  4. Degradation patterns of natural and synthetic textiles on a soil surface during summer and winter seasons studied using ATR-FTIR spectroscopy

    Science.gov (United States)

    Ueland, Maiken; Howes, Johanna M.; Forbes, Shari L.; Stuart, Barbara H.

    2017-10-01

    Textiles are a valuable source of forensic evidence and the nature and condition of textiles collected from a crime scene can assist investigators in determining the nature of the death and aid in the identification of the victim. Until now, much of the knowledge of textile degradation in forensic contexts has been based on the visual inspection of material collected from soil environments. The purpose of the current study was to investigate the potential of a more quantitative approach to the understanding of forensic textile degradation through the application of infrared spectroscopy. Degradation patterns of natural and synthetic textile materials as they were subjected to a natural outdoor environment in Australia were investigated. Cotton, polyester and polyester - cotton blend textiles were placed on a soil surface during the summer and winter seasons and were analysed over periods 1 and 1.5 years, respectively, and examined using attenuated total reflectance (ATR) spectroscopy. Statistical analysis of the spectral data obtained for the cotton material correlated with visual degradation and a difference in the onset of degradation between the summer and winter season was revealed. The synthetic material did not show any signs of degradation either visually or statistically throughout the experimental period and highlighted the importance of material type in terms of preservation. The cotton section from the polyester - cotton blend samples was found to behave in a similar manner to that of the 100% cotton samples, however principal component analysis (PCA) demonstrated that the degradation patterns were less distinct in both the summer and winter trial for the blend samples. These findings indicated that the presence of the synthetic material may have inhibited the degradation of the natural material. The use of statistics to analyse the spectral data obtained for textiles of forensic interest provides a better foundation for the interpretation of the data

  5. Short-chain ubiquitination is associated with the degradation rate of a cell-surface-resident bile salt export pump (BSEP/ABCB11).

    Science.gov (United States)

    Hayashi, Hisamitsu; Sugiyama, Yuichi

    2009-01-01

    The reduced expression of the bile salt export pump (BSEP/ABCB11) at the canalicular membrane is associated with cholestasis-induced hepatotoxicity due to the accumulation of bile acids in hepatocytes. We demonstrated previously that 4-phenylbutyrate (4PBA) treatment, a U.S. Food and Drug Administration-approved drug for the treatment of urea cycle disorders, induces the cell-surface expression of BSEP by prolonging the degradation rate of cell-surface-resident BSEP. On the other hand, BSEP mutations, E297G and D482G, found in progressive familial intrahepatic cholestasis type 2 (PFIC2), reduced it by shortening the degradation rate of cell-surface-resident BSEP. Therefore, to help the development of the medical treatment of cholestasis, we investigated the underlying mechanism by which 4PBA and PFIC2-type mutations affect the BSEP degradation from cell surface, focusing on short-chain ubiquitination. In Madin-Darby canine kidney II (MDCK II) cells expressing BSEP and rat canalicular membrane vesicles, the molecular mass of the mature form of BSEP/Bsep shifted from 170 to 190 kDa after ubiquitin modification (molecular mass, 8 kDa). Ubiquitination susceptibility of BSEP/Bsep was reduced in vitro and in vivo by 4PBA treatment and, conversely, was enhanced by BSEP mutations E297G and D482G. Moreover, biotin-labeling studies using MDCK II cells demonstrated that the degradation of cell-surface-resident chimeric protein fusing ubiquitin to BSEP was faster than that of BSEP itself. In conclusion, BSEP/Bsep is modified with two to three ubiquitins, and its ubiquitination is modulated by 4PBA treatment and PFIC2-type mutations. Modulation of short-chain ubiquitination can regulate the change in the degradation rate of cell-surface-resident BSEP by 4PBA treatment and PFIC2-type mutations.

  6. A dynamic ecosystem process model for understanding interactions between permafrost thawing and vegetation responses in the arctic

    Science.gov (United States)

    Xu, C.; Travis, B. J.; Fisher, R. A.; Wilson, C. J.; McDowell, N.

    2010-12-01

    The arctic is expected to play an important role in the Earth’s future climate due to the large carbon stocks that are stored in permafrost and peatlands, a substantial proportion of which may be released to the atmosphere due to permafrost thawing. There may be positive feedbacks of permafrost thawing on plant growth by releasing stored nitrogen and increasing rooting depth; however, vegetation response to other changing variables such as CO2 and temperature can also modify soil hydrology and energy fluxes, leading to either positive or negative feedbacks on permafrost thawing. Disentangling the interactions between permafrost thawing and vegetation growth is critical for assessing the potential role of arctic regions on current and future global carbon cycling. We have developed a mechanistic, regional, and spatially explicit dynamic ecosystem process model through the integration of a 3-D soil hydrology and biogeochemistry model (Arctic Hydrology, ARCHY) and a dynamic vegetation model (Ecosystem Demography, ED), to quantify the importance of plant-permafrost interactions to soil and plant carbon storage. This model integrates important processes including photosynthesis, transpiration, respiration, 3-D competition for light, 3-D soil hydrology, energy fluxes (ice melting in the soil and solar radiation interception by canopy), nitrogen cycles (microbial decomposition, nitrogen transportation in soil, passive and active nitrogen uptake by plants), species migration, and drought-related mortality. A sensitivity analysis has been implemented to assess the importance of the hydrological cycle, the nitrogen cycle and energy fluxes in regulating the above and below-ground carbon cycles in arctic regions. Our model can fill an important gap between field and global land surface models for assessing plot and regional level hypotheses in the context of global climate.

  7. Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change

    Science.gov (United States)

    Gaglioti, Benjamin V.; Mann, Daniel H.; Jones, Benjamin M.; Pohlman, John W.; Kunz, Michael L.; Wooller, Matthew J.

    2014-01-01

    Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of radiocarbon age-offsets (14C) between the bulk lake sediment and plant macrofossils deposited in an arctic lake as an archive for soil and permafrost OC release over the last 14,500 years. The lake traps and archives OC imported from the watershed and allows us to test whether prior warming events stimulated old carbon release and heightened age-offsets. Today, the age-offset (2 ka; thousand of calibrated years before A.D. 1950) and the depositional rate of ancient OC from the watershed into the lake are relatively low and similar to those during the Younger Dryas cold interval (occurring 12.9–11.7 ka). In contrast, age-offsets were higher (3.0–5.0 ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7–9.0 ka) and Bølling-Allerød periods (14.5–12.9 ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were ~10 times greater than today. Although permafrost OC was vulnerable to climate warming in the past, we suggest surface soil organic horizons and peat are presently limiting summer thaw and carbon release. As a result, the temperature threshold to trigger widespread permafrost OC release is higher than during previous warming events.

  8. The effect of fire and permafrost interactions on soil carbon accumulation in an upland black spruce ecosystem of interior Alaska: Implications for post-thaw carbon loss

    Science.gov (United States)

    O'Donnell, J. A.; Harden, J.W.; McGuire, A.D.; Kanevskiy, M.Z.; Jorgenson, M.T.; Xu, X.

    2011-01-01

    High-latitude regions store large amounts of organic carbon (OC) in active-layer soils and permafrost, accounting for nearly half of the global belowground OC pool. In the boreal region, recent warming has promoted changes in the fire regime, which may exacerbate rates of permafrost thaw and alter soil OC dynamics in both organic and mineral soil. We examined how interactions between fire and permafrost govern rates of soil OC accumulation in organic horizons, mineral soil of the active layer, and near-surface permafrost in a black spruce ecosystem of interior Alaska. To estimate OC accumulation rates, we used chronosequence, radiocarbon, and modeling approaches. We also developed a simple model to track long-term changes in soil OC stocks over past fire cycles and to evaluate the response of OC stocks to future changes in the fire regime. Our chronosequence and radiocarbon data indicate that OC turnover varies with soil depth, with fastest turnover occurring in shallow organic horizons (~60 years) and slowest turnover in near-surface permafrost (>3000 years). Modeling analysis indicates that OC accumulation in organic horizons was strongly governed by carbon losses via combustion and burial of charred remains in deep organic horizons. OC accumulation in mineral soil was influenced by active layer depth, which determined the proportion of mineral OC in a thawed or frozen state and thus, determined loss rates via decomposition. Our model results suggest that future changes in fire regime will result in substantial reductions in OC stocks, largely from the deep organic horizon. Additional OC losses will result from fire-induced thawing of near-surface permafrost. From these findings, we conclude that the vulnerability of deep OC stocks to future warming is closely linked to the sensitivity of permafrost to wildfire disturbance. ?? 2010 Blackwell Publishing Ltd.

  9. Hydrological processes and permafrost regulate magnitude, source and chemical characteristics of dissolved organic carbon export in a peatland catchment of northeastern China

    Science.gov (United States)

    Guo, Yuedong; Song, Changchun; Tan, Wenwen; Wang, Xianwei; Lu, Yongzheng

    2018-02-01

    Permafrost thawing in peatlands has the potential to alter the catchment export of dissolved organic carbon (DOC), thus influencing the carbon balance and cycling in linked aquatic and ocean ecosystems. Peatlands along the southern margins of the Eurasian permafrost are relatively underexplored despite the considerable risks associated with permafrost degradation due to climate warming. This study examined dynamics of DOC export from a permafrost peatland catchment located in northeastern China during the 2012 to 2014 growing seasons. The estimated annual DOC loads varied greatly between 3211 and 19 022 kg yr-1, with a mean DOC yield of 4.7 g m-2 yr-1. Although the estimated DOC yield was in the lower range compared with other permafrost regions, it was still significant for the net carbon balance in the studied catchment. There were strong linkages between daily discharge and DOC concentrations in both wet and dry years, suggesting a transport-limited process of DOC delivery from the catchment. Discharge explained the majority of both seasonal and interannual variations of DOC concentrations, which made annual discharge a good indicator of total DOC load from the catchment. As indicated by three fluorescence indices, DOC source and chemical characteristics tracked the shift of flow paths during runoff processes closely. Interactions between the flow path and DOC chemical characteristics were greatly influenced by the seasonal thawing of the soil active layer. The deepening of the active layer due to climate warming likely increases the proportion of microbial-originated DOC in baseflow discharge.

  10. The International Permafrost Association: current initiatives for cryospheric research

    Science.gov (United States)

    Schollaen, Karina; Lewkowicz, Antoni G.; Christiansen, Hanne H.; Romanovsky, Vladimir E.; Lantuit, Hugues; Schrott, Lothar; Sergeev, Dimitry; Wei, Ma

    2015-04-01

    The International Permafrost Association (IPA), founded in 1983, has as its objectives to foster the dissemination of knowledge concerning permafrost and to promote cooperation among persons and national or international organizations engaged in scientific investigation and engineering work on permafrost. The IPA's primary responsibilities are convening International Permafrost Conferences, undertaking special projects such as preparing databases, maps, bibliographies, and glossaries, and coordinating international field programs and networks. Membership is through adhering national or multinational organizations or as individuals in countries where no Adhering Body exists. The IPA is governed by its Executive Committee and a Council consisting of representatives from 26 Adhering Bodies having interests in some aspect of theoretical, basic and applied frozen ground research, including permafrost, seasonal frost, artificial freezing and periglacial phenomena. This presentation details the IPA core products, achievements and activities as well as current projects in cryospheric research. One of the most important core products is the circumpolar permafrost map. The IPA also fosters and supports the activities of the Global Terrestrial Network on Permafrost (GTN-P) sponsored by the Global Terrestrial Observing System, GTOS, and the Global Climate Observing System, GCOS, whose long-term goal is to obtain a comprehensive view of the spatial structure, trends, and variability of changes in the active layer thickness and permafrost temperature. A further important initiative of the IPA are the biannually competitively-funded Action Groups which work towards the production of well-defined products over a period of two years. Current IPA Action Groups are working on highly topical and interdisciplinary issues, such as the development of a regional Palaeo-map of Permafrost in Eurasia, the integration of multidisciplinary knowledge about the use of thermokarst and permafrost

  11. Visualization of low-contrast surface modifications: Thin films, printed pattern, laser-induced changes, imperfections, impurities, and degradation

    Science.gov (United States)

    Stockmann, J.; Hertwig, A.; Beck, U.

    2017-11-01

    Visualization of surface modifications may be very challenging for coating/substrate systems of either almost identical optical constants, e.g. transparent films on substrates of the same material, or minor film thickness, substance quantity and affected area, e.g. ultra-thin or island films. Methods for visualization are optical microscopy (OM), imaging ellipsometry (IE), and referenced spectroscopic ellipsometry (RSE). Imaging ellipsometry operates at oblique incidence near Brewster angle of the bare, clean or unmodified substrate. In this configuration, reflected intensities are rather weak. However, the contrast to add-on and sub-off features may be superior. Referenced spectroscopic ellipsometry operates in a two-sample configuration but with much higher intensities. In many cases, both ellipsometric techniques reveal and visualize thin films, printed-pattern, laser-induced changes, and impurities better than optical microscopy. In particular for stratified homogeneous modifications, ellipsometric techniques give access to modelling and hence thickness determination. Modifications under investigation are polymer foil residue on silicon, laser-induced changes of ta-C:H coatings on 100Cr6 steel, imperfections of ta-C:H on thermal silicon oxide, degradation of glass, thin film tin oxide pattern on silicon, printed and dried pattern of liquids such as deionized water, cleaning agents, and dissolved silicone.

  12. Degradation of the starch components amylopectin and amylose by barley α-amylase 1: Role of surface binding site 2

    DEFF Research Database (Denmark)

    Nielsen, Jonas Willum; Kramhøft, Birte; Bozonnet, Sophie

    2012-01-01

    Barley α-amylase isozyme 1 (AMY1, EC 3.2.1.1) contains two surface binding sites, SBS1 and SBS2, involved in the degradation of starch granules. The distinct role of SBS1 and SBS2 remains to be fully understood. Mutational analysis of Tyr-380 situated at SBS2 previously revealed that Tyr-380...... is required for binding of the amylose helix mimic, β-cyclodextrin. Also, mutant enzymes altered at position 380 displayed reduced binding to starch granules. Similarly, binding of wild type AMY1 to starch granules was suppressed in the presence of β-cyclodextrin. We investigated the role of SBS2 by comparing...... kinetic properties of the wild type AMY1 and the Y380A mutant enzyme in hydrolysis of amylopectin, amylose and β-limit dextrin, and the inhibition by β-cyclodextrin. Progress curves of the release of reducing ends revealed a bi-exponential hydrolysis of amylopectin and β-limit dextrin, whereas hydrolysis...

  13. Analysis of ERT data of geoelectrical permafrost monitoring on Hoher Sonnblick (Austrian Central Alps)

    Science.gov (United States)

    Pfeiler, Stefan; Schöner, Wolfgang; Reisenhofer, Stefan; Ottowitz, David; Jochum, Birgit; Kim, Jung-Ho; Hoyer, Stefan; Supper, Robert; Heinrich, Georg

    2016-04-01

    In the Alps infrastructure facilities such as roads, routes or buildings are affected by the changes of permafrost, which often cause enormous reparation costs. Investigation on degradation of Alpine Permafrost in the last decade has increased, however, the understanding of the permafrost changes inducing its atmospheric forcing processes is still insufficient. Within the project ATMOperm the application of the geoelectrical method to estimate thawing layer thickness for mountain permafrost is investigated near the highest meteorological observatory of Austria on the Hoher Sonnblick. Therefore, it is necessary to further optimize the transformation of ERT data to thermal changes in the subsurface. Based on an innovative time lapse inversion routine for ERT data (Kim J.-H. et al 2013) a newly developed data analysis software tool developed by Kim Jung-Ho (KIGAM) in cooperation with the Geophysics group of the Geological Survey of Austria allows the statistical analysis of the entire sample set of each and every data point measured by the geoelectrical monitoring instrument. This gives on the one hand of course an enhanced opportunity to separate between „good" and „bad" data points in order to assess the quality of measurements. On the other hand, the results of the statistical analysis define the impact of every single data point on the inversion routine. The interpretation of the inversion results will be supplemented by temperature logs from selected boreholes along the ERT profile as well as climatic parameters. KIM J.-H., SUPPER R., TSOURLOS P. and YI M.-J.: Four-dimensional inversion of resistivity monitoring data through Lp norm minimizations. - Geophysical Journal International, 195(3), 1640-1656, 2013. Doi: 10.1093/gji/ggt324. (No OA) Acknowledgments: The geoelectrical monitoring on Hoher Sonnblick has been installed and is operated in the frame of the project ATMOperm (Atmosphere - permafrost relationship in the Austrian Alps - atmospheric extreme

  14. Electrical and seismic mixing rules for detecting changes in ground ice content in permafrost studies

    Science.gov (United States)

    Hauck, Christian; Hilbich, Christin

    2017-04-01

    Geophysical methods are now widely used in permafrost research to detect and monitor frozen ground and potentially quantify the ground ice content in the soil. Hereby, often a combination of different methods is used to reduce the ambiguities inherent with the indirect nature of geophysical surveys. Geophysical mixing rules and petrophysical relationships originally developed by exploration industry may help to quantitatively relate geophysical variables such as the electrical resistivity or the seismic P-wave velocity to the physical properties of the subsurface. Two of these mixing rules were combined by Hauck et al. (2011) in a so-called 4-phase model to attempt to quantify the ground ice, air- and water content and their changes with time in permafrost environments (e.g. Pellet et al. 2016). However, these mixing rules are often either empirically derived (making use of a large number of borehole samples) or based on a simplified mixing model, i.e. an equal weighting of each phase component (ice, water, soil/rock, air) depending on the actual fractional content of each phase. There is thus no obvious 'best choice' model from the available geophysical approaches. Stimulated by recent theoretical work by Glover (2010), who analysed the relationships between the empirical and theory-derived mixing models, this contribution aims to analyse the applicability of various mixing models for electrical and seismic data sets in the context of detecting and monitoring permafrost degradation. Input data stem from various geophysical surveys around the world and ground truth data for validation is available from corresponding permafrost boreholes from the PERMOS and GTN-P data bases. Glover, P. W. (2010). A generalized Archie's law for n phases. Geophysics, 75(6), E247-E265. Hauck, C., Böttcher, M. and Maurer, H. (2011): A new model for estimating subsurface ice content based on combined electrical and seismic data sets. The Cryosphere, 5, 453-468. Pellet C., Hilbich C

  15. Anaerobic methanotrophic communities thrive in deep submarine permafrost.

    Science.gov (United States)

    Winkel, Matthias; Mitzscherling, Julia; Overduin, Pier P; Horn, Fabian; Winterfeld, Maria; Rijkers, Ruud; Grigoriev, Mikhail N; Knoblauch, Christian; Mangelsdorf, Kai; Wagner, Dirk; Liebner, Susanne

    2018-01-22

    Thawing submarine permafrost is a source of methane to the subsurface biosphere. Methane oxidation in submarine permafrost sediments has been proposed, but the responsible microorganisms remain uncharacterized. We analyzed archaeal communities and identified distinct anaerobic methanotrophic assemblages of marine and terrestrial origin (ANME-2a/b, ANME-2d) both in frozen and completely thawed submarine permafrost sediments. Besides archaea potentially involved in anaerobic oxidation of methane (AOM) we found a large diversity of archaea mainly belonging to Bathyarchaeota, Thaumarchaeota, and Euryarchaeota. Methane concentrations and δ 13 C-methane signatures distinguish horizons of potential AOM coupled either to sulfate reduction in a sulfate-methane transition zone (SMTZ) or to the reduction of other electron acceptors, such as iron, manganese or nitrate. Analysis of functional marker genes (mcrA) and fluorescence in situ hybridization (FISH) corroborate potential activity of AOM communities in submarine permafrost sediments at low temperatures. Modeled potential AOM consumes 72-100% of submarine permafrost methane and up to 1.2 Tg of carbon per year for the total expected area of submarine permafrost. This is comparable with AOM habitats such as cold seeps. We thus propose that AOM is active where submarine permafrost thaws, which should be included in global methane budgets.

  16. Permafrost stores a globally significant amount of mercury

    Science.gov (United States)

    Schuster, Paul F.; Schaefer, Kevin; Aiken, George R.; Antweiler, Ronald C.; DeWild, John F.; Gryziec, Joshua D.; Gusmeroli, Alessio; Hugelius, Gustaf; Jafarov, Elchin E.; Krabbenhoft, David P.; Liu, Lin; Herman-Mercer, Nicole M.; Mu, Cuicui; Roth, David A.; Schaefer, Tim; Striegl, Robert G.; Wickland, Kimberly P.; Zhang, Tingjun

    2018-01-01

    Changing climate in northern regions is causing permafrost to thaw with major implications for the global mercury (Hg) cycle. We estimated Hg in permafrost regions based on in situ measurements of sediment total mercury (STHg), soil organic carbon (SOC), and the Hg to carbon ratio (RHgC) combined with maps of soil carbon. We measured a median STHg of 43 ± 30 ng Hg g soil−1 and a median RHgC of 1.6 ± 0.9 μg Hg g C−1, consistent with published results of STHg for tundra soils and 11,000 measurements from 4,926 temperate, nonpermafrost sites in North America and Eurasia. We estimate that the Northern Hemisphere permafrost regions contain 1,656 ± 962 Gg Hg, of which 793 ± 461 Gg Hg is frozen in permafrost. Permafrost soils store nearly twice as much Hg as all other soils, the ocean, and the atmosphere combined, and this Hg is vulnerable to release as permafrost thaws over the next century. Existing estimates greatly underestimate Hg in permafrost soils, indicating a need to reevaluate the role of the Arctic regions in the global Hg cycle.

  17. Permafrost Stores a Globally Significant Amount of Mercury

    Science.gov (United States)

    Schuster, Paul F.; Schaefer, Kevin M.; Aiken, George R.; Antweiler, Ronald C.; Dewild, John F.; Gryziec, Joshua D.; Gusmeroli, Alessio; Hugelius, Gustaf; Jafarov, Elchin; Krabbenhoft, David P.; Liu, Lin; Herman-Mercer, Nicole; Mu, Cuicui; Roth, David A.; Schaefer, Tim; Striegl, Robert G.; Wickland, Kimberly P.; Zhang, Tingjun

    2018-02-01

    Changing climate in northern regions is causing permafrost to thaw with major implications for the global mercury (Hg) cycle. We estimated Hg in permafrost regions based on in situ measurements of sediment total mercury (STHg), soil organic carbon (SOC), and the Hg to carbon ratio (RHgC) combined with maps of soil carbon. We measured a median STHg of 43 ± 30 ng Hg g soil-1 and a median RHgC of 1.6 ± 0.9 μg Hg g C-1, consistent with published results of STHg for tundra soils and 11,000 measurements from 4,926 temperate, nonpermafrost sites in North America and Eurasia. We estimate that the Northern Hemisphere permafrost regions contain 1,656 ± 962 Gg Hg, of which 793 ± 461 Gg Hg is frozen in permafrost. Permafrost soils store nearly twice as much Hg as all other soils, the ocean, and the atmosphere combined, and this Hg is vulnerable to release as permafrost thaws over the next century. Existing estimates greatly underestimate Hg in permafrost soils, indicating a need to reevaluate the role of the Arctic regions in the global Hg cycle.

  18. Regional atmospheric cooling and wetting effect of permafrost thaw-induced boreal forest loss.

    Science.gov (United States)

    Helbig, Manuel; Wischnewski, Karoline; Kljun, Natascha; Chasmer, Laura E; Quinton, William L; Detto, Matteo; Sonnentag, Oliver

    2016-12-01

    In the sporadic permafrost zone of North America, thaw-induced boreal forest loss is leading to permafrost-free wetland expansion. These land cover changes alter landscape-scale surface properties with potentially large, however, still unknown impacts on regional climates. In this study, we combine nested eddy covariance flux tower measurements with satellite remote sensing to characterize the impacts of boreal forest loss on albedo, eco-physiological and aerodynamic surface properties, and turbulent energy fluxes of a lowland boreal forest region in the Northwest Territories, Canada. Planetary boundary layer modelling is used to estimate the potential forest loss impact on regional air temperature and atmospheric moisture. We show that thaw-induced conversion of forests to wetlands increases albedo: and bulk surface conductance for water vapour and decreases aerodynamic surface temperature. At the same time, heat transfer efficiency is reduced. These shifts in land surface properties increase latent at the expense of sensible heat fluxes, thus, drastically reducing Bowen ratios. Due to the lower albedo of forests and their masking effect of highly reflective snow, available energy is lower in wetlands, especially in late winter. Modelling results demonstrate that a conversion of a present-day boreal forest-wetland to a hypothetical homogeneous wetland landscape could induce a near-surface cooling effect on regional air temperatures of up to 3-4 °C in late winter and 1-2 °C in summer. An atmospheric wetting effect in summer is indicated by a maximum increase in water vapour mixing ratios of 2 mmol mol -1 . At the same time, maximum boundary layer heights are reduced by about a third of the original height. In fall, simulated air temperature and atmospheric moisture between the two scenarios do not differ. Therefore, permafrost thaw-induced boreal forest loss may modify regional precipitation patterns and slow down regional warming trends. © 2016 John Wiley

  19. Using remote sensing and ancillary data to extend airborne electromagnetic resistivity surveys for regional permafrost interpretation

    Science.gov (United States)

    Pastick, N.; Wylie, B. K.; Minsley, B. J.; Jorgenson, T. T.; Ji, L.; Walvoord, M. A.; Smith, B. D.; Abraham, J. D.; Rose, J.

    2011-12-01

    Permafrost has a significant impact on high latitude ecosystems and is spatially heterogeneous. However, only generalized maps of permafrost extent are available. Due to its impacts on subsurface hydrology, lake water levels, vegetation communities, and surface soil deformations, understanding the spatial extents and depth of permafrost are critical. Electrical resistivity increases dramatically as a soil freezes and can be used as a proxy for permafrost presence particularly if the underlying soils and geologic characteristics are understood. An airborne electromagnetic survey (AEM) was conducted over a portion of the Yukon Flats ecoregion in central Alaska with measurements taken in both reconnaissance lines and contiguous block area coverage. The AEM was flown in June 2010 and subsurface resistivity models were derived by inverting the AEM data. Landsat TM at-sensor reflectance, thermal, and spectral index data from late August to early September 2008, Digital Elevation Models (DEM) and derivatives, and other ancillary data were used in a regression tree model to predict near surface electrical resistivity at the 0-1m and the 0-2.6m depth intervals. AEM locations from homogenous landsat 90 m by 90 m windows were randomly separated into a training set for model development (n = 8,848) and an impendent test data set (n = 988) for model accuracy assessment. Model development and independent test accuracies for 0-1 m electric resistivity had training and test R2 values of 0.90 and 0.87, respectively, and for the 0-2.6m electric resistivity training and test R2 values were also 0.90 and 0.87, respectively, which indicated accurate prediction models. Important variables for stratifying the various piecewise regressions were elevation and averaged 2000-2008 ecosystem performance anomalies. Important independent variables used in the multiple regression equations were the Normalized Difference Infrared Index (NDII), NDII7 (NDII using band 7), soil moisture mapped from

  20. Comparing the sensitivity of permafrost and marine gas hydrate to climate warming

    International Nuclear Information System (INIS)

    Taylor, A.E.; Dallimore, S.R.; Hyndman, R.D.; Wright, F.

    2005-01-01

    The sensitivity of Arctic subpermafrost gas hydrate at the Mallik borehole was compared to temperate marine gas hydrate located offshore southwestern Canada. In particular, a finite element geothermal model was used to determine the sensitivity to the end of the ice age, and contemporary climate warming of a 30 m thick methane hydrate layer lying at the base of a gas hydrate stability zone prior to 13.5 kiloannum (ka) before present (BP). It was suggested that the 30 m gas-hydrate-bearing layer would have disappeared by now, according to the thermal signal alone. However, the same gas-hydrate-bearing layer underlying permafrost would persist until at least 4 ka after present, even with contemporary climate warming. The longer time for subpermafrost gas hydrate comes from the thawing pore ice at the base of permafrost, at the expense of dissociation of the deeper gas hydrate. The dissociation of underlying gas hydrate from climate surface warming is buffered by the overlying permafrost

  1. Evaluation of the Committed Carbon Emissions and Global Warming due to the Permafrost Carbon Feedback

    Science.gov (United States)

    Elshorbany, Y. F.; Schaefer, K. M.; Jafarov, E. E.; Yumashev, D.; Hope, C.

    2017-12-01

    We quantify the increase in carbon emissions and temperature due to Permafrost Carbon feedback (PCF), defined as the amplification of anthropogenic warming due to carbon emissions from thawing permafrost (i.e., of near-surface layers to 3 m depth). We simulate the Committed PCF emissions, the cumulative total emissions from thawing permafrost by 2300 for a given global temperature increase by 2100, and investigate the resulting global warming using the Simple Biosphere/Carnegie-Ames-Stanford Approach SiBCASA model. We estimate the committed PCF emissions and warming for the Fifth Assessment Report, Representative Concentration Pathway scenarios 4.5 and 8.5 using two ensembles of five projections. For the 2 °C warming target of the global climate change treaty, committed PCF emissions increase to 24 Gt C by 2100 and 76 Gt C by 2300 and the committed PCF warming is 0.23 °C by 2300. Our calculations show that as the global temperature increase by 2100 approaches 5.8 °C, the entire stock of frozen carbon thaws out, resulting in maximum committed PCF emissions of 560 Gt C by 2300.

  2. Cryopegs as destabilization factor of intra-permafrost gas hydrates

    Science.gov (United States)

    Chuvilin, Evgeny; Bukhanov, Boris; Istomin, Vladimir

    2016-04-01

    A characteristic feature of permafrost soils in the Arctic is widespread intra-permafrost unfrozen brine lenses - cryopegs. They are often found in permafrost horizons in the north part of Western Siberia, in particular, on the Yamal Peninsula. Cryopegs depths in permafrost zone can be tens and hundreds of meters from the top of frozen strata. The chemical composition of natural cryopegs is close to sea waters, but is characterized by high mineralization. They have a sodium-chloride primary composition with a minor amount of sulphate. Mineralization of cryopegs brine is often hundreds of grams per liter, and the temperature is around -6…-8 °C. The formation of cryopegs in permafrost is associated with processes of long-term freezing of sediments and cryogenic concentration of salts and salt solutions in local areas. The cryopegs' formation can take place in the course of permafrost evolution at the sea transgressions and regressions during freezing of saline sea sediments. Very important feature of cryopegs in permafrost is their transformation in the process of changing temperature and pressure conditions. As a result, the salinity and chemical composition are changed and in addition the cryopegs' location can be changed during their migration. The cryopegs migration violates the thermodynamic conditions of existence intra-permafrost gas hydrate formations, especially the relic gas hydrates deposits, which are situated in the shallow permafrost up to 100 meters depth in a metastable state [1]. The interaction cryopegs with gas hydrates accumulations can cause decomposition of intra-permafrost hydrates. Moreover, the increasing of salt and unfrozen water content in sedimentary rocks sharply reduce the efficiency of gas hydrates self-preservation in frozen soils. It is confirmed by experimental investigations of interaction of frozen gas hydrate bearing sediments with salt solutions [2]. So, horizons with elevated pressure can appear, as a result of gas hydrate

  3. Improving permafrost distribution modelling using feature selection algorithms

    Science.gov (United States)

    Deluigi, Nicola; Lambiel, Christophe; Kanevski, Mikhail

    2016-04-01

    The availability of an increasing number of spatial data on the occurrence of mountain permafrost allows the employment of machine learning (ML) classification algorithms for modelling the distribution of the phenomenon. One of the major problems when dealing with high-dimensional dataset is the number of input features (variables) involved. Application of ML classification algorithms to this large number of variables leads to the risk of overfitting, with the consequence of a poor generalization/prediction. For this reason, applying feature selection (FS) techniques helps simplifying the amount of factors required and improves the knowledge on adopted features and their relation with the studied phenomenon. Moreover, taking away irrelevant or redundant variables from the dataset effectively improves the quality of the ML prediction. This research deals with a comparative analysis of permafrost distribution models supported by FS variable importance assessment. The input dataset (dimension = 20-25, 10 m spatial resolution) was constructed using landcover maps, climate data and DEM derived variables (altitude, aspect, slope, terrain curvature, solar radiation, etc.). It was completed with permafrost evidences (geophysical and thermal data and rock glacier inventories) that serve as training permafrost data. Used FS algorithms informed about variables that appeared less statistically important for permafrost presence/absence. Three different algorithms were compared: Information Gain (IG), Correlation-based Feature Selection (CFS) and Random Forest (RF). IG is a filter technique that evaluates the worth of a predictor by measuring the information gain with respect to the permafrost presence/absence. Conversely, CFS is a wrapper technique that evaluates the worth of a subset of predictors by considering the individual predictive ability of each variable along with the degree of redundancy between them. Finally, RF is a ML algorithm that performs FS as part of its

  4. Seepage erosion of Arctic coastal bluffs driven by thawing permafrost in Northwest Alaska

    Science.gov (United States)

    Phillips, C. B.; Jerolmack, D. J.; Crosby, B. T.

    2010-12-01

    On the forefront of transient landscapes is the Arctic. Air and sea surface temperatures have increased significantly in the last 50 years due to anthropogenic warming, and have been blamed for observed accelerations in coastal erosion rates and the formation of thermokarst features. The controls that permafrost exerts on landforms and sediment transport are largely unknown, but may be elucidated by examining landscape response to permafrost thaw. Using current and historical aerial photos of Northwest Alaska we identified an area of coastal bluffs experiencing increased erosion. What makes this portion of the coast unusual is that erosion is not driven by thermomechanical action from waves, however waves are important in the removal of material from the base of the slump. Instead, retrogressive slump failures - which have seen accelerated growth in the 1900s - initiated the growth of headward cutting alcoves that have now penetrated up to a hundred meters inland. Our field topographic surveys reveal that slumps decrease in slope and increase in circularity with increasing size, suggesting a temporal growth progression toward an asymptotic quasi-circular planform shape. Morphometric scaling relationships suggest that groundwater seepage erosion may be driving alcove growth. Junction angles of alcoves, and the trajectories of headcutting measured from repeat aerial photography, also support a model of ground water competition as the primary mechanism of continued growth. Coastal erosion rates do not depend on solar radiation flux; we propose therefore that seepage water is derived from a vertical lowering of the permafrost table, by thaw resulting from increased ambient air temperatures. Slump features such as those observed here are expected to become more