WorldWideScience

Sample records for arctic permafrost soil

  1. Plant-derived compounds stimulate the decomposition of organic matter in arctic permafrost soils

    Science.gov (United States)

    Wild, Birgit; Gentsch, Norman; Čapek, Petr; Diáková, Kateřina; Alves, Ricardo J. Eloy; Bárta, Jiři; Gittel, Antje; Hugelius, Gustaf; Knoltsch, Anna; Kuhry, Peter; Lashchinskiy, Nikolay; Mikutta, Robert; Palmtag, Juri; Schleper, Christa; Schnecker, Jörg; Shibistova, Olga; Takriti, Mounir; Torsvik, Vigdis L.; Urich, Tim; Watzka, Margarete; Šantrůčková, Hana; Guggenberger, Georg; Richter, Andreas

    2016-05-01

    Arctic ecosystems are warming rapidly, which is expected to promote soil organic matter (SOM) decomposition. In addition to the direct warming effect, decomposition can also be indirectly stimulated via increased plant productivity and plant-soil C allocation, and this so called “priming effect” might significantly alter the ecosystem C balance. In this study, we provide first mechanistic insights into the susceptibility of SOM decomposition in arctic permafrost soils to priming. By comparing 119 soils from four locations across the Siberian Arctic that cover all horizons of active layer and upper permafrost, we found that an increased availability of plant-derived organic C particularly stimulated decomposition in subsoil horizons where most of the arctic soil carbon is located. Considering the 1,035 Pg of arctic soil carbon, such an additional stimulation of decomposition beyond the direct temperature effect can accelerate net ecosystem C losses, and amplify the positive feedback to global warming.

  2. Spatial variation in vegetation productivity trends, fire disturbance, and soil carbon across arctic-boreal permafrost ecosystems

    Science.gov (United States)

    Loranty, Michael M.; Liberman-Cribbin, Wil; Berner, Logan T.; Natali, Susan M.; Goetz, Scott J.; Alexander, Heather D.; Kholodov, Alexander L.

    2016-09-01

    In arctic tundra and boreal forest ecosystems vegetation structural and functional influences on the surface energy balance can strongly influence permafrost soil temperatures. As such, vegetation changes will likely play an important role in permafrost soil carbon dynamics and associated climate feedbacks. Processes that lead to changes in vegetation, such as wildfire or ecosystem responses to rising temperatures, are of critical importance to understanding the impacts of arctic and boreal ecosystems on future climate. Yet these processes vary within and between ecosystems and this variability has not been systematically characterized across the arctic-boreal region. Here we quantify the distribution of vegetation productivity trends, wildfire, and near-surface soil carbon, by vegetation type, across the zones of continuous and discontinuous permafrost. Siberian larch forests contain more than one quarter of permafrost soil carbon in areas of continuous permafrost. We observe pervasive positive trends in vegetation productivity in areas of continuous permafrost, whereas areas underlain by discontinuous permafrost have proportionally less positive productivity trends and an increase in areas exhibiting negative productivity trends. Fire affects a much smaller proportion of the total area and thus a smaller amount of permafrost soil carbon, with the vast majority occurring in deciduous needleleaf forests. Our results indicate that vegetation productivity trends may be linked to permafrost distribution, fire affects a relatively small proportion of permafrost soil carbon, and Siberian larch forests will play a crucial role in the strength of the permafrost carbon climate feedback.

  3. Permafrost-Affected Soils of the Russian Arctic and their Carbon Pools

    Science.gov (United States)

    Zubrzycki, S.; Kutzbach, L.; Pfeiffer, E.-M.

    2014-02-01

    Permafrost-affected soils have accumulated enormous pools of organic matter during the Quaternary Period. The area occupied by these soils amounts to more than 8.6 million km2, which is about 27% of all land areas north of 50° N. Therefore, permafrost-affected soils are considered to be one of the most important cryosphere elements within the climate system. Due to the cryopedogenic processes that form these particular soils and the overlying vegetation that is adapted to the arctic climate, organic matter has accumulated to the present extent of up to 1024 Pg (1 Pg = 1015 g = 1 Gt) of soil organic carbon stored within the uppermost three meters of ground. Considering the observed progressive climate change and the projected polar amplification, permafrost-affected soils will undergo fundamental property changes. Higher turnover and mineralization rates of the organic matter are consequences of these changes, which are expected to result in an increased release of climate-relevant trace gases into the atmosphere. As a result, permafrost regions with their distinctive soils are likely to trigger an important tipping point within the global climate system, with additional political and social implications. The controversy of whether permafrost regions continue accumulating carbon or already function as a carbon source remains open until today. An increased focus on this subject matter, especially in underrepresented Siberian regions, could contribute to a more robust estimation of the soil organic carbon pool of permafrost regions and at the same time improve the understanding of the carbon sink and source functions of permafrost-affected soils.

  4. Permafrost thawing in organic Arctic soils accelerated by ground heat production

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn;

    2015-01-01

    Decomposition of organic carbon from thawing permafrost soils and the resulting release of carbon to the atmosphere are considered to represent a potentially critical global-scale feedback on climate change1, 2. The accompanying heat production from microbial metabolism of organic material has been...... organic permafrost soils across Greenland and tested the hypothesis that these soils produce enough heat to reach a tipping point after which internal heat production can accelerate the decomposition processes. Results show that the impact of climate changes on natural organic soils can be accelerated...... by microbial heat production with crucial implications for the amounts of carbon being decomposed. The same is shown to be true for organic middens5 with the risk of losing unique evidence of early human presence in the Arctic....

  5. Priming in permafrost soils: High vulnerability of arctic soil organic carbon to increased input of plant-derived compounds

    Science.gov (United States)

    Wild, Birgit; Gentsch, Norman; Capek, Petr; Diakova, Katerina; Alves, Ricardo; Barta, Jiri; Gittel, Antje; Guggenberger, Georg; Lashchinskiy, Nikolay; Knoltsch, Anna; Mikutta, Robert; Santruckova, Hana; Schnecker, Jörg; Shibistova, Olga; Takriti, Mounir; Urich, Tim; Watzka, Margarete; Richter, Andreas

    2015-04-01

    Arctic ecosystems are warming rapidly, resulting in a stimulation of both plant primary production and soil organic matter (SOM) decomposition. In addition to this direct stimulation, SOM decomposition might also be indirectly affected by rising temperatures mediated by the increase in plant productivity. Higher root litter production for instance might decrease SOM decomposition by providing soil microorganisms with alternative C and N sources ("negative priming"), or might increase SOM decomposition by facilitating microbial growth and enzyme production ("positive priming"). With about 1,700 Pg of organic C stored in arctic soils, and 88% of that in horizons deeper than 30 cm, it is crucial to understand the controls on SOM decomposition in different horizons of arctic permafrost soils, and thus the vulnerability of SOM to changes in C and N availability in a future climate. We here report on the vulnerability of SOM in arctic permafrost soils to an increased input of plant-derived organic compounds, and on its variability across soil horizons and sites. We simulated an increased input of plant-derived compounds by amending soil samples with 13C-labelled cellulose or protein, and compared the mineralization of native, unlabelled soil organic C (SOC) to unamended control samples. Our experiment included 119 individual samples of arctic permafrost soils, covering four sites across the Siberian Arctic, and five soil horizons, i.e., organic topsoil, mineral topsoil, mineral subsoil and cryoturbated material (topsoil material buried in the subsoil by freeze-thaw processes) from the active layer, as well as thawed material from the upper permafrost. Our findings suggest that changes in C and N availability in Arctic soils, such as mediated by plants, have a high potential to alter the decomposition of SOM, but also point at fundamental differences between soil horizons. In the organic topsoil, SOC mineralization increased by 51% after addition of protein, but was not

  6. Input of easily available organic C and N stimulates microbial decomposition of soil organic matter in arctic permafrost soil.

    Science.gov (United States)

    Wild, Birgit; Schnecker, Jörg; Alves, Ricardo J Eloy; Barsukov, Pavel; Bárta, Jiří; Capek, Petr; Gentsch, Norman; Gittel, Antje; Guggenberger, Georg; Lashchinskiy, Nikolay; Mikutta, Robert; Rusalimova, Olga; Santrůčková, Hana; Shibistova, Olga; Urich, Tim; Watzka, Margarete; Zrazhevskaya, Galina; Richter, Andreas

    2014-08-01

    Rising temperatures in the Arctic can affect soil organic matter (SOM) decomposition directly and indirectly, by increasing plant primary production and thus the allocation of plant-derived organic compounds into the soil. Such compounds, for example root exudates or decaying fine roots, are easily available for microorganisms, and can alter the decomposition of older SOM ("priming effect"). We here report on a SOM priming experiment in the active layer of a permafrost soil from the central Siberian Arctic, comparing responses of organic topsoil, mineral subsoil, and cryoturbated subsoil material (i.e., poorly decomposed topsoil material subducted into the subsoil by freeze-thaw processes) to additions of (13)C-labeled glucose, cellulose, a mixture of amino acids, and protein (added at levels corresponding to approximately 1% of soil organic carbon). SOM decomposition in the topsoil was barely affected by higher availability of organic compounds, whereas SOM decomposition in both subsoil horizons responded strongly. In the mineral subsoil, SOM decomposition increased by a factor of two to three after any substrate addition (glucose, cellulose, amino acids, protein), suggesting that the microbial decomposer community was limited in energy to break down more complex components of SOM. In the cryoturbated horizon, SOM decomposition increased by a factor of two after addition of amino acids or protein, but was not significantly affected by glucose or cellulose, indicating nitrogen rather than energy limitation. Since the stimulation of SOM decomposition in cryoturbated material was not connected to microbial growth or to a change in microbial community composition, the additional nitrogen was likely invested in the production of extracellular enzymes required for SOM decomposition. Our findings provide a first mechanistic understanding of priming in permafrost soils and suggest that an increase in the availability of organic carbon or nitrogen, e.g., by increased plant

  7. Relating the Chemical Composition of Dissolved Organic Matter Draining Permafrost Soils to its Photochemical Degradation in Arctic Surface Waters.

    Science.gov (United States)

    Ward, C.; Cory, R. M.

    2015-12-01

    Thawing permafrost soils are expected to shift the chemical composition of DOM exported to and degraded in arctic surface waters. While DOM photo-degradation is an important component of the freshwater C cycle in the Arctic, the molecular controls on DOM photo-degradation remain poorly understood, making it difficult to predict how shifting chemical composition may alter DOM photo-degradation in arctic surface waters. To address this knowledge gap, we quantified the susceptibility of DOM draining the shallow organic mat and the deeper permafrost layer to complete photo-oxidation to CO₂ and partial photo-oxidation to compounds that remain in the DOM pool, and investigated changes in DOM chemical composition following sunlight exposure. DOM leached from the organic mat contained higher molecular weight, more oxidized and unsaturated aromatic species compared to permafrost DOM. Despite significant differences in initial chemical composition, permafrost and organic mat DOM had similar susceptibilities to complete photo-oxidation to CO₂. Concurrent losses of carboxyl moieties and shifts in chemical composition during photo-degradation indicated that carboxyl-rich tannin-like compounds in both DOM sources were likely photo-decarboxylated to CO₂. Permafrost DOM had a higher susceptibility to partial photo-oxidation compared to organic mat DOM, potentially due to a lower abundance of phenolic compounds that act as "antioxidants" and slow the oxidation of DOM. These results demonstrated how chemical composition controls the photo-degradation of DOM in arctic surface waters, and that DOM photo-degradation will likely remain an important component of the freshwater C budget in the Arctic with increased export of permafrost DOM to surface waters.

  8. Storage and transformation of organic matter fractions in cryoturbated permafrost soils across the Siberian Arctic

    Directory of Open Access Journals (Sweden)

    N. Gentsch

    2015-02-01

    Full Text Available In permafrost soils, the temperature regime and the resulting cryogenic processes are decisive for the storage of organic carbon (OC and its small-scale spatial variability. For cryoturbated soils there is a lack in the assessment of pedon-scale heterogeneity in OC stocks and the transformation of functionally different organic matter (OM fractions such as particulate and mineral-associated OM. Therefore, pedons of 28 Turbels across the Siberian Arctic were sampled in five meter wide soil trenches in order to calculate OC and total nitrogen (TN stocks within the active layer and the upper permafrost based on digital profile mapping. Density fractionation of soil samples was performed to distinguish particulate OM (light fraction, LF, −3, mineral associated OM (heavy fraction, HF, >1.6 g cm−3, and a mobilizable dissolved pool (mobilizable fraction, MoF. Mineral-organic associations were characterized by selective extraction of pedogenic Fe and Al oxides and the clay composition was analyzed by X-ray diffraction. Organic matter transformation in bulk soil and density fractions was assessed by the stable carbon isotope ratio (δ13C and element contents (C and N. Across all investigated soil profiles, total OC stocks were calculated to 20.2 ± 8.0 kg m−2 (mean ± SD to 100 cm soil depth. Of this average, 54% of the OC was located in active layer horizons (annual summer thawing layer showing evidence of cryoturbation, and another 35% was present in the permafrost. The HF-OC dominated the overall OC stocks (55% followed by LF-OC (19% in mineral and 13% in organic horizons. During fractionation about 13% of the OC was released as MoF, which likely represents the most bioavailable OM pool. Cryogenic activity combined with an impaired biodegradation in topsoil horizons (O and A horizons were the principle mechanisms to sequester large OC stocks in the subsoil (16.4 ± 8.1 kg m−2; all mineral B, C, and permafrost horizons. About 22% of the subsoil

  9. Carbon monoxide photoproduction: implications for photoreactivity of Arctic permafrost-derived soil dissolved organic matter.

    Science.gov (United States)

    Hong, Jun; Xie, Huixiang; Guo, Laodong; Song, Guisheng

    2014-08-19

    Apparent quantum yields of carbon monoxide (CO) photoproduction (AQY(CO)) for permafrost-derived soil dissolved organic matter (SDOM) from the Yukon River Basin and Alaska coast were determined to examine the dependences of AQY(CO) on temperature, ionic strength, pH, and SDOM concentration. SDOM from different locations and soil depths all exhibited similar AQY(CO) spectra irrespective of soil age. AQY(CO) increased by 68% for a 20 °C warming, decreased by 25% from ionic strength 0 to 0.7 mol L(-1), and dropped by 25-38% from pH 4 to 8. These effects combined together could reduce AQY(CO) by up to 72% when SDOM transits from terrestrial environemnts to open-ocean conditions during summer in the Arctic. A Michaelis-Menten kinetics characterized the influence of SDOM dilution on AQY(CO) with a very low substrate half-saturation concentration. Generalized global-scale relationships between AQY(CO) and salinity and absorbance demostrate that the CO-based photoreactivity of ancient permaforst SDOM is comparable to that of modern riverine DOM and that the effects of the physicochemical variables revealed here alone could account for the seaward decline of AQY(CO) observed in diverse estuarine and coastal water bodies.

  10. Surface exposure to sunlight stimulates CO2 release from permafrost soil carbon in the Arctic.

    Science.gov (United States)

    Cory, Rose M; Crump, Byron C; Dobkowski, Jason A; Kling, George W

    2013-02-26

    Recent climate change has increased arctic soil temperatures and thawed large areas of permafrost, allowing for microbial respiration of previously frozen C. Furthermore, soil destabilization from melting ice has caused an increase in thermokarst failures that expose buried C and release dissolved organic C (DOC) to surface waters. Once exposed, the fate of this C is unknown but will depend on its reactivity to sunlight and microbial attack, and the light available at the surface. In this study we manipulated water released from areas of thermokarst activity to show that newly exposed DOC is >40% more susceptible to microbial conversion to CO(2) when exposed to UV light than when kept dark. When integrated over the water column of receiving rivers, this susceptibility translates to the light-stimulated bacterial activity being on average from 11% to 40% of the total areal activity in turbid versus DOC-colored rivers, respectively. The range of DOC lability to microbes seems to depend on prior light exposure, implying that sunlight may act as an amplification factor in the conversion of frozen C stores to C gases in the atmosphere.

  11. Permafrost thawing in organic Arctic soils accelerated by ground heat production

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Matthiesen, Henning; Moller, Anders Bjorn;

    2015-01-01

    Decomposition of organic carbon from thawing permafrost soils and the resulting release of carbon to the atmosphere are considered to represent a potentially critical global-scale feedback on climate change1, 2. The accompanying heat production from microbial metabolism of organic material has been...... recognized as a potential positive-feedback mechanism that would enhance permafrost thawing and the release of carbon3, 4. This internal heat production is poorly understood, however, and the strength of this effect remains unclear3. Here, we have quantified the variability of heat production in contrasting...... organic permafrost soils across Greenland and tested the hypothesis that these soils produce enough heat to reach a tipping point after which internal heat production can accelerate the decomposition processes. Results show that the impact of climate changes on natural organic soils can be accelerated...

  12. Permafrost Soils Database for Northern Alaska 2014

    Data.gov (United States)

    Arctic Landscape Conservation Cooperative — This database contains soil and permafrost stratigraphy for northern Alaska compiled from numerous project data files and reports. The Access Database has main data...

  13. The Impact of Climate Change on Microbial Communities and Carbon Cycling in High Arctic Permafrost Soil from Spitsbergen, Northern Norway

    Science.gov (United States)

    de Leon, K. C.; Schwery, D.; Yoshikawa, K.; Christiansen, H. H.; Pearce, D.

    2014-12-01

    Permafrost-affected soils are among the most fragile ecosystems in which current microbial controls on organic matter decomposition are changing as a result of climate change. Warmer conditions in the high Arctic will lead to a deepening of the seasonal active layer of permafrost, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. The viable and non-viable fractions of the microbial community in a permafrost soil from Adventdalen, Spitsbergen, Norway were subjected to a comprehensive investigation using culture-dependent and culture-independent methods. Molecular analyses using FISH (with CTC-DAPI) and amplified rDNA restriction analysis (ARDRA) on a 257cm deep core, revealed the presence of all major microbial soil groups, with the active layer having more viable cells, and a higher microbial community diversity. Carbon dioxide (CO2) and methane (CH4) flux measurements were performed to show the amount of C stored in the sample. We demonstrated that the microbial community composition from the soil in the center of the core was most likely influenced by small scale variations in environmental conditions. Community structure showed distinct shift of presence of bacterial groups along the vertical temperature gradient profile and microbial counts and diversity was found to be highest in the surface layers, decreasing with depth. It was observed that soil properties driving microbial diversity and functional potential varied across the permafrost table. Data on the variability of CO2 and CH4 distribution described in peat structure heterogeneity are important for modeling emissions on a larger scale. Furthermore, linking microbial biomass to gas distribution may elucidate the cause of peak CO2 and CH4 and their changes in relation to environmental change and peat composition.

  14. Permafrost soils and carbon cycling

    OpenAIRE

    Ping, C. L.; J. D. Jastrow; Jorgenson, M. T.; G. J. Michaelson; Y. L. Shur

    2015-01-01

    Knowledge of soils in the permafrost region has advanced immensely in recent decades, despite the remoteness and inaccessibility of most of the region and the sampling limitations posed by the severe environment. These efforts significantly increased estimates of the amount of organic carbon stored in permafrost-region soils and improved understanding of how pedogenic processes unique to permafrost environments built enormous organic carbon stocks during the Quaternary. This...

  15. Surface towed electromagnetic system for mapping of subsea Arctic permafrost

    Science.gov (United States)

    Sherman, Dallas; Kannberg, Peter; Constable, Steven

    2017-02-01

    Sea level has risen globally since the late Pleistocene, resulting in permafrost-bearing coastal zones in the Arctic being submerged and subjected to temperature induced degradation. Knowing the extent of permafrost and how it changes over time is important for climate change predictions and for planning engineering activities in the Arctic environment. We developed a controlled source electromagnetic (CSEM) method to obtain information on the depth, thickness, and lateral extent of marine permafrost. To operate in shallow water we used a surface towed electric dipole-dipole CSEM system suitable for deployment from small boats. This system was used to map permafrost on the Arctic shelf offshore Prudhoe Bay, Alaska. Our results show significant lateral variability in the presence of permafrost, with the thickest layers associated with a large river outflow where freshwater influx seems to have a preserving effect on relict subsea permafrost.

  16. Beaded streams of Arctic permafrost landscapes

    Directory of Open Access Journals (Sweden)

    C. D. Arp

    2014-07-01

    Full Text Available Beaded streams are widespread in permafrost regions and are considered a common thermokarst landform. However, little is known about their distribution, how and under what conditions they form, and how their intriguing morphology translates to ecosystem functions and habitat. Here we report on a Circum-Arctic inventory of beaded streams and a watershed-scale analysis in northern Alaska using remote sensing and field studies. We mapped over 400 channel networks with beaded morphology throughout the continuous permafrost zone of northern Alaska, Canada, and Russia and found the highest abundance associated with medium- to high-ice content permafrost in moderately sloping terrain. In the Fish Creek watershed, beaded streams accounted for half of the drainage density, occurring primarily as low-order channels initiating from lakes and drained lake basins. Beaded streams predictably transition to alluvial channels with increasing drainage area and decreasing channel slope, although this transition is modified by local controls on water and sediment delivery. Comparison of one beaded channel using repeat photography between 1948 and 2013 indicate relatively stable form and 14C dating of basal sediments suggest channel formation may be as early as the Pleistocene–Holocene transition. Contemporary processes, such as deep snow accumulation in stream gulches effectively insulates river ice and allows for perennial liquid water below most beaded stream pools. Because of this, mean annual temperatures in pool beds are greater than 2 °C, leading to the development of perennial thaw bulbs or taliks underlying these thermokarst features. In the summer, some pools stratify thermally, which reduces permafrost thaw and maintains coldwater habitats. Snowmelt generated peak-flows decrease rapidly by two or more orders of magnitude to summer low flows with slow reach-scale velocity distributions ranging from 0.1 to 0.01 m s−1, yet channel runs still move water

  17. Methane emissions proportional to permafrost carbon thawed in Arctic lakes since the 1950s

    Science.gov (United States)

    Walter Anthony, Katey; Daanen, Ronald; Anthony, Peter; Schneider von Deimling, Thomas; Ping, Chien-Lu; Chanton, Jeffrey P.; Grosse, Guido

    2016-09-01

    Permafrost thaw exposes previously frozen soil organic matter to microbial decomposition. This process generates methane and carbon dioxide, and thereby fuels a positive feedback process that leads to further warming and thaw. Despite widespread permafrost degradation during the past ~40 years, the degree to which permafrost thaw may be contributing to a feedback between warming and thaw in recent decades is not well understood. Radiocarbon evidence of modern emissions of ancient permafrost carbon is also sparse. Here we combine radiocarbon dating of lake bubble trace-gas methane (113 measurements) and soil organic carbon (289 measurements) for lakes in Alaska, Canada, Sweden and Siberia with numerical modelling of thaw and remote sensing of thermokarst shore expansion. Methane emissions from thermokarst areas of lakes that have expanded over the past 60 years were directly proportional to the mass of soil carbon inputs to the lakes from the erosion of thawing permafrost. Radiocarbon dating indicates that methane age from lakes is nearly identical to the age of permafrost soil carbon thawing around them. Based on this evidence of landscape-scale permafrost carbon feedback, we estimate that 0.2 to 2.5 Pg permafrost carbon was released as methane and carbon dioxide in thermokarst expansion zones of pan-Arctic lakes during the past 60 years.

  18. Microbial Carbon Cycling in Permafrost-Affected Soils

    Energy Technology Data Exchange (ETDEWEB)

    Vishnivetskaya, T. [University of Tennessee, Knoxville (UTK); Liebner, Susanne [University of Tromso, Norway; Wilhelm, Ronald [McGill University, Montreal, Quebec; Wagner, Dirk [Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany

    2011-01-01

    The Arctic plays a key role in Earth s climate system as global warming is predicted to be most pronounced at high latitudes and because one third of the global carbon pool is stored in ecosystems of the northern latitudes. In order to improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosystems, present studies concentrate on investigations of microbial controls of greenhouse gas fluxes, on the activity and structure of the involved microbial communities, and on their response to changing environmental conditions. Permafrost-affected soils can function as both a source and a sink for carbon dioxide and methane. Under anaerobic conditions, caused by flooding of the active layer and the effect of backwater above the permafrost table, the mineralization of organic matter can only be realized stepwise by specialized microorganisms. Important intermediates of the organic matter decomposition are hydrogen, carbon dioxide and acetate, which can be further reduced to methane by methanogenic archaea. Evolution of methane fluxes across the subsurface/atmosphere boundary will thereby strongly depend on the activity of anaerobic methanogenic archaea and obligately aerobic methane oxidizing proteobacteria, which are known to be abundant and to significantly reduce methane emissions in permafrost-affected soils. Therefore current studies on methane-cycling microorganisms are the object of particular attention in permafrost studies, because of their key role in the Arctic methane cycle and consequently of their significance for the global methane budget.

  19. 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

  20. Sensitivity of Arctic Permafrost Carbon in the Mackenzie River Basin: A substrate addition and incubation experiment

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    Hedgpeth, A.; Beilman, D.; Crow, S. E.

    2014-12-01

    Arctic soil organic matter (SOM) mineralization processes are fundamental to the functioning of high latitude soils in relation to nutrients, stability, and feedbacks to atmospheric CO2 and climate. The arctic permafrost zone covers 25% of the northern hemisphere and contains 1672Pg of soil carbon (C). 88% of this C currently resides in frozen soils that are vulnerable to environmental change. For instance, arctic growing seasons may be lengthened, resulting in an increase in plant productivity and rate of below ground labile C inputs as root exudates. Understanding controls on Arctic SOM dynamics requires recognition that labile C inputs have the potential to significantly affect mineralization of previously stable SOM, also known as 'priming effects'. We conducted a substrate addition incubation experiment to quantify and compare respiration in highly organic (42-48 %C) permafrost soils along a north-south transect in western Canada. Near surface soils (10-20 cm) were collected from permafrost peatland sites in the Mackenzie River Basin from 69.2-62.6°N. The surface soils are fairly young (Δ14C values > -140.0) and can be assumed to contain relatively reactive soil carbon. To assess whether addition of labile substrate alters SOM decomposition dynamics, 4.77-11.75 g of permafrost soil were spiked with 0.5 mg D-glucose g-1 soil and incubated at 5°C. A mass balance approach was used to determin substrate-induced respiration and preliminary results suggest a potential for positive priming in these C-rich soils. Baseline respiration rates from the three sites were similar (0.067-0.263 mg CO2 g-1 soil C) yet show some site-specific trends. The rate at which added substrate was utilized within these soils suggests that other factors besides temperature and soil C content are controlling substrate consumption and its effect on SOM decomposition. Microbial activity can be stimulated by substrate addition to such an extent that SOM turnover is enhanced, suggesting that

  1. 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.

  2. 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

  3. Complete and Partial Photo-oxidation of Dissolved Organic Matter Draining Permafrost Soils.

    Science.gov (United States)

    Ward, Collin P; Cory, Rose M

    2016-04-05

    Photochemical degradation of dissolved organic matter (DOM) to carbon dioxide (CO2) and partially oxidized compounds is an important component of the carbon cycle in the Arctic. Thawing permafrost soils will change the chemical composition of DOM exported to arctic surface waters, but the molecular controls on DOM photodegradation remain poorly understood, making it difficult to predict how inputs of thawing permafrost DOM may alter its photodegradation. To address this knowledge gap, we quantified the susceptibility of DOM draining the shallow organic mat and the deeper permafrost layer of arctic soils to complete and partial photo-oxidation and investigated changes in the chemical composition of each DOM source following sunlight exposure. Permafrost and organic mat DOM had similar lability to photomineralization despite substantial differences in initial chemical composition. Concurrent losses of carboxyl moieties and shifts in chemical composition during photodegradation indicated that photodecarboxylation could account for 40-90% of DOM photomineralized to CO2. Permafrost DOM had a higher susceptibility to partial photo-oxidation compared to organic mat DOM, potentially due to a lower abundance of phenolic moieties with antioxidant properties. These results suggest that photodegradation will likely continue to be an important control on DOM fate in arctic freshwaters as the climate warms and permafrost soils thaw.

  4. Seasonal fluxes and age of particulate organic carbon exported from Arctic catchments impacted by localized permafrost slope disturbances

    Science.gov (United States)

    Lamoureux, Scott F.; Lafrenière, Melissa J.

    2014-04-01

    Projected warming is expected to alter the Arctic permafrost regime with potential impacts on hydrological fluxes of particulate organic carbon (POC) and sediment. Previous work has focused on large Arctic basins and revealed the important contribution of old carbon in river POC, but little is known about POC fluxes from smaller coastal watersheds, particularly where widespread postglacial raised marine sediments represent a potential source of old soil carbon that could be mobilized by permafrost disturbance. To evaluate these processes, the characteristics of POC, particulate nitrogen (PN) and suspended sediment transport from paired small coastal Arctic watersheds subject to recent permafrost disturbance were investigated at the Cape Bounty Arctic Watershed Observatory (CBAWO) in the Canadian High Arctic. Approximately 2% of the total suspended sediment load from both watersheds was composed of POC and the majority of the sediment and POC fluxes occurred during the spring snowmelt period. Radiocarbon analysis of POC indicates recent permafrost disturbances deliver substantially older POC to the aquatic system. Localized permafrost slope disturbances have a measurable influence on downstream POC age and dominate (estimated up to 78% of POC) sediment fluxes during summer baseflow. The elevation of disturbances and Holocene emergence data show limited age sensitivity of POC to the location of disturbance and suggest slope failures are likely to deliver carbon with a relatively similar age range to the aquatic system, regardless of landscape location.

  5. Climate Change, Degradation of Permafrost, and Hazards to Infrastructure in the Circumpolar Arctic.

    Science.gov (United States)

    Anisimov, O.

    2001-12-01

    Warming, thawing and disappearance of permafrost have accelerated in recent decades damaging engineered structures and raising public concerns. By the middle of the 21st century anthropogenic climate change may cause 2 to 3 C warming of the frozen ground, 10% to 16% reduction of the total permafrost area, 30% to 50% deepening of the active-layer thickness, and shifts between the permafrost zones due to cumulative effect of changing surface temperature, soil moisture, and vegetation. Such changes will have important implications for northern engineering and infrastructure built upon permafrost. The foundations supporting engineered structures are designed for the constant climatic conditions with construction-specific safety factor, which in the practice of the cold-region engineering varies typically from 5% to 60% with respect to the bearing capacity. In the zone of discontinuous permafrost a 2.0 C rise in air temperature may decrease the bearing capacity of frozen ground under buildings by more than a half. This may have important consequences for the infrastructure and particularly for residential buildings constructed in the permafrost zone between 1950 and 1990 in northern Russian cities Vorkuta, Yakytsk, Norylsk, and Magadan. Many of them are already weakened or damaged, which may in part be attributed to the effect of climate change. Susceptibility of permafrost to environmental hazards associated with thermokarst, ground settlement, and other destructive cryogenic processes may be crudely evaluated using the geocryological hazard index, which is the combination of the predicted for the future climate relative change in the active-layer thickness and the ground ice content. Predictive maps constructed for scenarios of climate change indicated that several population centers (Barrow, Inuvik), river terminals on the arctic coast of Russia (Salekhard, Igarka, Dudinka, Tiksi), and gas production complexes with associated infrastructure in northwest Siberia fall

  6. Landscape controls and vertical variability of soil organic carbon storage in permafrost-affected soils of the Lena River Delta

    DEFF Research Database (Denmark)

    Siewert, Matthias Benjamin; Hugelius, Gustaf; Heim, Birgit

    2016-01-01

    To project the future development of the soil organic carbon (SOC) storage in permafrost environments, the spatial and vertical distribution of key soil properties and their landscape controls needs to be understood. This article reports findings from the Arctic Lena River Delta where we sampled ...

  7. Effect of snow cover on pan-Arctic permafrost thermal regimes

    Science.gov (United States)

    Park, Hotaek; Fedorov, Alexander N.; Zheleznyak, Mikhail N.; Konstantinov, Pavel Y.; Walsh, John E.

    2015-05-01

    This study quantitatively evaluated how insulation by snow depth (SND) affected the soil thermal regime and permafrost degradation in the pan-Arctic area, and more generally defined the characteristics of soil temperature (TSOIL) and SND from 1901 to 2009. This was achieved through experiments performed with the land surface model CHANGE to assess sensitivity to winter precipitation as well as air temperature. Simulated TSOIL, active layer thickness (ALT), SND, and snow density were generally comparable with in situ or satellite observations at large scales and over long periods. Northernmost regions had snow that remained relatively stable and in a thicker state during the past four decades, generating greater increases in TSOIL. Changes in snow cover have led to changes in the thermal state of the underlying soil, which is strongly dependent on both the magnitude and the timing of changes in snowfall. Simulations of the period 2001-2009 revealed significant differences in the extent of near-surface permafrost, reflecting differences in the model's treatment of meteorology and the soil bottom boundary. Permafrost loss was greater when SND increased in autumn rather than in winter, due to insulation of the soil resulting from early cooling. Simulations revealed that TSOIL tended to increase over most of the pan-Arctic from 1901 to 2009, and that this increase was significant in northern regions, especially in northeastern Siberia where SND is responsible for 50 % or more of the changes in TSOIL at a depth of 3.6 m. In the same region, ALT also increased at a rate of approximately 2.3 cm per decade. The most sensitive response of ALT to changes in SND appeared in the southern boundary regions of permafrost, in contrast to permafrost temperatures within the 60°N-80°N region, which were more sensitive to changes in snow cover. Finally, our model suggests that snow cover contributes to the warming of permafrost in northern regions and could play a more important role

  8. 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.

  9. 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, M.; 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

  10. 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

  11. Reviews and Syntheses: Effects of permafrost thaw on arctic aquatic ecosystems

    Directory of Open Access Journals (Sweden)

    J. E. Vonk

    2015-07-01

    Full Text Available The Arctic is a water-rich region, with freshwater systems covering 16 % of the northern permafrost landscape. The thawing of this permafrost 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 and lotic 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 variables determine the degree to which permafrost thaw manifests as thermokarst, whether thermokarst leads to slumping or the formation of thermokarst lakes, and 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 variables 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 systems is also likely to change, with thaw-impacted lakes and streams having unique microbiological communities, and showing 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

  12. Strategizing a Comprehensive Laboratory Protocol to Determine the Decomposability of Soil Organic Matter in Permafrost

    Science.gov (United States)

    Schaedel, C.; Ernakovich, J. G.; Harden, J. W.; Natali, S.; Richter, A.; Schuur, E.; Treat, C. C.

    2015-12-01

    Soil organic matter decomposition depends on physical, chemical, and biological factors, such as the amount and quality of the organic matter stored, abiotic conditions (such as soil temperature and moisture), microbial community dynamics, and physical protection by soil minerals. Soils store immense amounts of carbon with 1330-1580 Pg of carbon in the permafrost region alone. Increasing temperatures in the Arctic will thaw large amounts of previously frozen organic carbon making it available for decomposition. The rate at which carbon is being released from permafrost soils is crucial for understanding future changes in permafrost carbon storage and carbon flux to the atmosphere. The potential magnitude and form of carbon release (carbon dioxide or methane) from permafrost can be investigated using soil incubation studies. Over the past 20 years, many incubation studies have been published with soils from the permafrost zone and three recent syntheses have summarized current findings from aerobic and anaerobic incubation studies. However, the breadth of the incubation synthesis projects was hampered by incomplete meta-data and the use of different methods. Here, we provide recommendations to improve and standardize future soil incubation studies (which are not limited to permafrost soils) to make individual studies useful for inclusion in syntheses and meta-analyses, which helps to broaden their impact on our understanding of organic matter cycling. Additionally, we identify gaps in the understanding of permafrost carbon decomposability, that, when coupled with emerging knowledge from field observations and experiments, can be implemented in future studies to gain a better overview of the overall decomposability of permafrost carbon.

  13. 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

    As Arctic regions warm and frozen soils thaw, the large organic carbon pool stored in permafrost becomes increasingly vulnerable to decomposition or transport. The transfer of newly mobilized carbon to the atmosphere and its potential influence upon climate change will largely depend on the degradability of carbon delivered to aquatic ecosystems. Dissolved organic carbon (DOC) is a key regulator of aquatic metabolism, yet knowledge of the mechanistic controls on DOC biodegradability is currently poor due to a scarcity of long-term data sets, limited spatial coverage of available data, and methodological diversity. Here, we performed parallel biodegradable DOC (BDOC) experiments at six Arctic sites (16 experiments) using a standardized incubation protocol to examine the effect of methodological differences commonly used in the literature. We also synthesized results from 14 aquatic and soil leachate BDOC studies from across the circum-arctic permafrost region to examine pan-arctic trends in BDOC.An increasing extent of permafrost across the landscape resulted in higher DOC losses in both soil and aquatic systems. We hypothesize that the unique composition of (yedoma) permafrost-derived DOC combined with limited prior microbial processing due to low soil temperature and relatively short flow path lengths and transport times, contributed to a higher overall terrestrial and freshwater DOC loss. Additionally, we found that the fraction of BDOC decreased moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly biodegradable DOC is lost in headwater streams. We also observed a seasonal (January–December) decrease in BDOC in large streams and rivers, but saw no apparent change in smaller streams or soil leachates. We attribute this seasonal change to a combination of factors including shifts in carbon source, changing DOC residence time related to increasing thaw-depth, increasing water temperatures later

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

    Science.gov (United States)

    Vonk, J. E.; Tank, S. E.; Mann, P. J.; Spencer, R. G. M.; Treat, C. C.; Striegl, R. G.; Abbott, B. W.; Wickland, K. P.

    2015-12-01

    As Arctic regions warm and frozen soils thaw, the large organic carbon pool stored in permafrost becomes increasingly vulnerable to decomposition or transport. The transfer of newly mobilized carbon to the atmosphere and its potential influence upon climate change will largely depend on the degradability of carbon delivered to aquatic ecosystems. Dissolved organic carbon (DOC) is a key regulator of aquatic metabolism, yet knowledge of the mechanistic controls on DOC biodegradability is currently poor due to a scarcity of long-term data sets, limited spatial coverage of available data, and methodological diversity. Here, we performed parallel biodegradable DOC (BDOC) experiments at six Arctic sites (16 experiments) using a standardized incubation protocol to examine the effect of methodological differences commonly used in the literature. We also synthesized results from 14 aquatic and soil leachate BDOC studies from across the circum-arctic permafrost region to examine pan-arctic trends in BDOC. An increasing extent of permafrost across the landscape resulted in higher DOC losses in both soil and aquatic systems. We hypothesize that the unique composition of (yedoma) permafrost-derived DOC combined with limited prior microbial processing due to low soil temperature and relatively short flow path lengths and transport times, contributed to a higher overall terrestrial and freshwater DOC loss. Additionally, we found that the fraction of BDOC decreased moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly biodegradable DOC is lost in headwater streams. We also observed a seasonal (January-December) decrease in BDOC in large streams and rivers, but saw no apparent change in smaller streams or soil leachates. We attribute this seasonal change to a combination of factors including shifts in carbon source, changing DOC residence time related to increasing thaw-depth, increasing water temperatures later

  15. Carbon Cycling in Alpine and Arctic watersheds affected by permafrost degradation: An insight from Sweden

    Science.gov (United States)

    Roehm, C. L.; Giesler, R.; Karlsson, J.

    2009-05-01

    Linking the processes and dynamics acting within and between terrestrial and aquatic ecosystems is crucial in order to understand the impacts of environmental change on the re-distribution and transformation of energy within watersheds. Nearly 1300 Pg of carbon are stored in permafrost soils in boreal and arctic ecosystems. Permafrost degradation can result in the loss of significant amounts of terrestrial carbon, both through the release to the atmosphere in the form of carbon dioxide and methane, or through export downstream to lakes and rivers. The fate and effects of this carbon in lake ecosystems is poorly understood. We investigated the capacity of lake bacteria to utilize carbon from different adjacent mire soils in a discontinuous permafrost region of northern Sweden. We, additionally, studied other lake ecosystems by using organic matter quality as a proxy for the state of permafrost degradation within the watershed. Finally, we propose simple predictive models for the bioavailability of soils to aquatic bacteria. Our study identified three distinctive time sensitive pools of bacterial respiration whose carbon availability varied according to chemical characteristics. Soil dissolved organic carbon (DOC) was rapidly consumed by lake bacteria with nearly 85% consumed within the first 24 hours. Bacterial production was higher in the soil bioassays and increased in a lag fashion relative to bacterial respiration, resulting in increasing bacterial growth efficiencies over time as a function of C pool and soil type. The mean DOC consumption by lake bacteria was 0.087 mg C L-1 d-1 and varied between 0.382 mg L-1 d-1 and 0.491 mg L-1 d-1 when supplied with terrestrial DOC. The lake water bacterial respiration could explain a varying degree of pCO2 saturation in lakes as a function of both carbon quality and course. Carbon quality and end members can be used as proxies for the degree of permafrost degradation within the watershed. The data clearly show that export

  16. Biodegradability of dissolved organic carbon in permafrost soils and waterways: a meta-analysis

    Science.gov (United States)

    Vonk, J. E.; Tank, S. E.; Mann, P. J.; Spencer, R. G. M.; Treat, C. C.; Striegl, R. G.; Abbott, B. W.; Wickland, K. P.

    2015-06-01

    As Arctic regions warm, the large organic carbon pool stored in permafrost becomes increasingly vulnerable to thaw and decomposition. The transfer of newly mobilized carbon to the atmosphere and its potential influence upon climate change will largely depend on the reactivity and subsequent fate of carbon delivered to aquatic ecosystems. Dissolved organic carbon (DOC) is a key regulator of aquatic metabolism and its biodegradability will determine the extent and rate of carbon release from aquatic ecosystems to the atmosphere. Knowledge of the mechanistic controls on DOC biodegradability is however currently poor due to a scarcity of long-term data sets, limited spatial coverage of available data, and methodological diversity. Here, we performed parallel biodegradable DOC (BDOC) experiments at six Arctic sites (16 experiments) using a standardized incubation protocol to examine the effect of methodological differences used as common practice in the literature. We further synthesized results from 14 aquatic and soil leachate BDOC studies from across the circum-arctic permafrost region to examine pan-Arctic trends in BDOC. An increasing extent of permafrost across the landscape resulted in higher BDOC losses in both soil and aquatic systems. We hypothesize that the unique composition of permafrost-derived DOC combined with limited prior microbial processing due to low soil temperature and relatively shorter flow path lengths and transport times, resulted in higher overall terrestrial and freshwater BDOC loss. Additionally, we found that the fraction of BDOC decreased moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly biodegradable DOC is lost in headwater streams. We also observed a seasonal (January-December) decrease in BDOC losses in large streams and rivers, but no apparent change in smaller streams and soil leachates. We attribute this seasonal change to a combination of factors including

  17. The Lena River Delta Observatory, Arctic Siberia: a Contribution to the ESA DUE Permafrost Project

    Science.gov (United States)

    Heim, Birgit; Boike, Julia; Moritz, Langer; Annett, Bartsch; Sina, Muster; Jennifer, Sobiech; Konstanze, Piel; Günter, Stoof; Anne, Morgenstern; Mathias, Ulrich

    2010-05-01

    The major task of the ESA Data User Element DUE PERMAFROST is to develop and use Earth Observation services specifically for monitoring and modelling of permafrost. In order to setup the required information services, a target area approach with specified case study regions is used. Long-term ground data series and multidisciplinary ongoing projects make the Lena River delta (Arctic Siberia) a prime study region for evaluation and validation of the DUE PERMAFROST remote sensing products. The Lena River Delta located in the zone of continuous permafrost is a key region for Arctic system science. Since 1998, the Alfred Wegener Institute for Polar and Marine Research AWI in collaboration with the Lena Delta Reserve in Tiksi has operated the German-Russian research station Samoylov. Relevant ground-based data (air temperature, radiation, snow, albedo, soil temperature and moisture) are collected continuously. The high landscape heterogeneity (wet polygonal centres, dry polygonal rims, ponds and lakes) challenges all ground data observations. Match-up data sets of ground data and remote sensing products coincident in time and location are being built up. Exclusion and selection criteria will be based on experience, especially the knowledge on parameter variability in time and space. The main focus are the remote sensing products ‘surface temperature', ‘surface moisture', ‘albedo', ‘vegetation' and ‘water'. Statistical and contextural methods will be used for the upscaling from the plot to the meso-scale. Problems will have to be identified such as process-dependent scales and the water body ratio within the pixel.

  18. 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.

  19. The transcriptional response of microbial communities in thawing Alaskan permafrost soils.

    Science.gov (United States)

    Coolen, Marco J L; Orsi, William D

    2015-01-01

    Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gasses, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throughput Illumina HiSeq sequencing of reverse transcribed messenger RNA to obtain a detailed overview of active metabolic pathways and responsible organisms in up to 70 cm deep permafrost soils at a moist acidic tundra location in Arctic Alaska. The transcriptional response of the permafrost microbial community was compared before and after 11 days of thaw. In general, the transcriptional profile under frozen conditions suggests a dominance of stress responses, survival strategies, and maintenance processes, whereas upon thaw a rapid enzymatic response to decomposing soil organic matter (SOM) was observed. Bacteroidetes, Firmicutes, ascomycete fungi, and methanogens were responsible for largest transcriptional response upon thaw. Transcripts indicative of heterotrophic methanogenic pathways utilizing acetate, methanol, and methylamine were found predominantly in the permafrost table after thaw. Furthermore, transcripts involved in acetogenesis were expressed exclusively after thaw suggesting that acetogenic bacteria are a potential source of acetate for acetoclastic methanogenesis in freshly thawed permafrost. Metatranscriptomics is shown here to be a useful approach for inferring the activity of permafrost microbes that has potential to improve our understanding of permafrost SOM bioavailability and biogeochemical mechanisms contributing to greenhouse gas emissions as a result of permafrost thaw.

  20. The transcriptional response of microbial communities in thawing Alaskan permafrost soils

    Directory of Open Access Journals (Sweden)

    M J L Coolen

    2015-03-01

    Full Text Available Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gases, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throughput Illumina HiSeq sequencing of reverse transcribed messenger RNA to obtain a detailed overview of active metabolic pathways and responsible organisms in up to 70 cm deep permafrost soils at a moist acidic tundra location in Arctic Alaska. The transcriptional response of the permafrost microbial community was compared before and after eleven days of thaw. In general, the transcriptional profile under frozen conditions suggests a dominance of stress responses, survival strategies, and maintenance processes, whereas upon thaw a rapid enzymatic response to decomposing soil organic matter (SOM was observed. Bacteroidetes, Firmicutes, ascomycete fungi, and methanogens were responsible for largest transcriptional response upon thaw. Transcripts indicative of heterotrophic methanogenic pathways utilizing acetate, methanol, and methylamine were found predominantly in the permafrost table after thaw. Furthermore, transcripts involved in acetogenesis were expressed exclusively after thaw suggesting that acetogenic bacteria are a potential source of acetate for acetoclastic methanogenesis in freshly thawed permafrost. Metatranscriptomics is shown here to be a useful approach for inferring the activity of permafrost microbes that has potential to improve our understanding of permafrost SOM bioavailability and biogeochemical mechanisms contributing to greenhouse gas emissions as a result of permafrost thaw.

  1. Reviews and syntheses : Effects of permafrost thaw on Arctic aquatic ecosystems

    NARCIS (Netherlands)

    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.; Walter Anthony, K. M.; Wickland, K. 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 st

  2. Nonlinear thermal and moisture dynamics of high Arctic wetland polygons following permafrost disturbance

    Directory of Open Access Journals (Sweden)

    E. Godin

    2015-07-01

    Full Text Available Low-centre polygonal terrain developing within gentle sloping surfaces and lowlands in the high Arctic have a potential to retain snowmelt water in their bowl-shaped centre and as such are considered high latitude wetlands. Such wetlands in the continuous permafrost regions have an important ecological role in an otherwise generally arid region. In the valley of the glacier C-79 on Bylot Island (Nunavut, Canada, thermal erosion gullies are rapidly eroding the permafrost along ice wedges affecting the integrity of the polygons by breaching and collapsing the surrounding rims. While intact polygons were characterized by a relative homogeneity (topography, snow cover, maximum active layer thaw depth, ground moisture content, vegetation cover, eroded polygons had a non-linear response for the same elements following their perturbation. The heterogeneous nature of disturbed terrains impacts active layer thickness, ground ice aggradation in the upper portion of permafrost, soil moisture and vegetation dynamics, carbon storage and terrestrial green-house gas emissions.

  3. Aliphatic side chains of proteins as potential geomarkers of NOM liberated from the melting permafrost and discharged to the Arctic Ocean by the Kolyma River run off

    Science.gov (United States)

    Dubinenkov, I. V.; Perminova, I.; Kononikhin, A.; Nikolaev, E.; Hertkorn, N.; Bulygina, E. B.; Holmes, R. M.

    2011-12-01

    The Arctic ecosystem is highly sensitive to climate change. Global warming might have considerable effects on regional carbon cycling due to permafrost melting. Permafrost in the Arctic region represents an extremely large organic carbon reservoir mostly stored in the permafrost. Mobilization of just a small portion of carbon stored in Arctic soils will have considerable impacts on the flux of organic carbon from land to the Arctic Ocean, which can affect the Arctic environment. The Kolyma River watershed is one of the Arctic Ocean's largest. It is dominated by continuous permafrost which is underlain with rich organic soils susceptible to increased fluvial transport. The goal of the work was to analyze the structure of isolated natural organic matter from different fresh water environments of the Kolyma river basin. NOM was isolated from the Kolyma River main stream, its tributaries, a thermokarst lake, a floodplain stream and the permafrost. Solid phase extraction technique was used with Bond Elute PPL cartridges. Nuclear magnetic resonance spectroscopy (NMR) and Fourier Transform Ion Cyclotron Resonance Mass Spectroscopy (FTICRMS) was used for structural studies because of unsurpassed molecular level structural information provided by these high resolution magnetic resonance techniques. The NOM samples from the Kolyma River showed high contents of non-substituted aliphatic structures with a low content of aromatics and carbohydrates. Aliphatic nature may indicate a microbial source of NOM in the form of degraded terpenoids and hopanols. It was shown that almost all NOM samples from the rivers had similar molecular composition enriched with aliphatic units. The samples from permafrost mud streams were significantly different and contained sharp peptide signatures. In general, permafrost NOM contained much less degraded peptide residuest as compared to riverine samples. Identification of these residues showed the presence of branched amino acids (valine, alanine

  4. Estimation of permafrost thawing rates in a sub-arctic catchment using recession flow analysis

    Directory of Open Access Journals (Sweden)

    S. W. Lyon

    2009-05-01

    Full Text Available Permafrost thawing is likely to change the flow pathways taken by water as it moves through arctic and sub-arctic landscapes. The location and distribution of these pathways directly influence the carbon and other biogeochemical cycling in northern latitude catchments. While permafrost thawing due to climate change has been observed in the arctic and sub-arctic, direct observations of permafrost depth are difficult to perform at scales larger than a local scale. Using recession flow analysis, it may be possible to detect and estimate the rate of permafrost thawing based on a long-term streamflow record. We demonstrate the application of this approach to the sub-arctic Abiskojokken catchment in northern Sweden. Based on recession flow analysis, we estimate that permafrost in this catchment may be thawing at an average rate of about 0.9 cm/yr during the past 90 years. This estimated thawing rate is consistent with direct observations of permafrost thawing rates, ranging from 0.7 to 1.3 cm/yr over the past 30 years in the region.

  5. Potential Arctic tundra vegetation shifts in response to changing temperature, precipitation and permafrost thaw

    Science.gov (United States)

    van der Kolk, Henk-Jan; Heijmans, Monique M. P. D.; van Huissteden, Jacobus; Pullens, Jeroen W. M.; Berendse, Frank

    2016-11-01

    Over the past decades, vegetation and climate have changed significantly in the Arctic. Deciduous shrub cover is often assumed to expand in tundra landscapes, but more frequent abrupt permafrost thaw resulting in formation of thaw ponds could lead to vegetation shifts towards graminoid-dominated wetland. Which factors drive vegetation changes in the tundra ecosystem are still not sufficiently clear. In this study, the dynamic tundra vegetation model, NUCOM-tundra (NUtrient and COMpetition), was used to evaluate the consequences of climate change scenarios of warming and increasing precipitation for future tundra vegetation change. The model includes three plant functional types (moss, graminoids and shrubs), carbon and nitrogen cycling, water and permafrost dynamics and a simple thaw pond module. Climate scenario simulations were performed for 16 combinations of temperature and precipitation increases in five vegetation types representing a gradient from dry shrub-dominated to moist mixed and wet graminoid-dominated sites. Vegetation composition dynamics in currently mixed vegetation sites were dependent on both temperature and precipitation changes, with warming favouring shrub dominance and increased precipitation favouring graminoid abundance. Climate change simulations based on greenhouse gas emission scenarios in which temperature and precipitation increases were combined showed increases in biomass of both graminoids and shrubs, with graminoids increasing in abundance. The simulations suggest that shrub growth can be limited by very wet soil conditions and low nutrient supply, whereas graminoids have the advantage of being able to grow in a wide range of soil moisture conditions and have access to nutrients in deeper soil layers. Abrupt permafrost thaw initiating thaw pond formation led to complete domination of graminoids. However, due to increased drainage, shrubs could profit from such changes in adjacent areas. Both climate and thaw pond formation

  6. The Arctic CH4 sink and its implications for the permafrost carbon feedbacks to the global climate system

    Science.gov (United States)

    Juncher Jørgensen, Christian; Christiansen, Jesper; Mariager, Tue; Hugelius, Gustaf

    2016-04-01

    Using atmospheric methane (CH4), certain soil microbes are able to sustain their metabolism, and in turn remove this powerful greenhouse gas from the atmosphere. While the process of CH4 oxidation is a common feature in most natural and unmanaged ecosystems in temperate and boreal ecosystems, the interactions between soil physical properties and abiotic process drivers, net landscape exchange and spatial patterns across Arctic drylands remains highly uncertain. Recent works show consistent CH4 comsumption in upland dry tundra soils in Arctic and High Arctic environments (Christiansen et al., 2014, Biogeochemistry 122; Jørgensen et al., 2015, Nature Geoscience 8; Lau et al., 2015, The ISME Journal 9). In these dominantly dry or barren soil ecosystems, CH4 consumption has been observed to significantly exceed the amounts of CH4 emitted from adjacent wetlands. These observations point to a potentially important but largely overlooked component of the global soil-climate system interaction and a counterperspective to the conceptual understanding of the Arctic being a only a source of CH4. However, due to our limited knowledge of spatiotemporal occurrence of CH4 consumption across a wider range of the Arctic landscape we are left with substantial uncertainites and an overall unconstrained range estimate of this terrestrial CH4 sink and its potential effects on permafrost carbon feedback to the atmospheric CH4 concentration. To address this important knowledge gap and identify the most relevant spatial scaling parameters, we studied in situ CH4 net exchange across a large landscape transect on West Greenland. The transect representated soils formed from the dominant geological parent materials of dry upland tundra soils found in the ice-free land areas of Western Greenland, i.e. 1) granitic/gneissic parent material, 2) basaltic parent material and 3) sedimentary deposits. Results show that the dynamic variations in soil physical properties and soil hydrology exerts an

  7. New permafrost is forming around shrinking Arctic lakes, but will it last?

    Science.gov (United States)

    Briggs, Martin A.; Walvoord, Michelle A.; McKenzie, Jeffrey M.; Voss, Clifford I.; Day-Lewis, Frederick D.; Lane, Jr., John W.

    2014-01-01

    Widespread lake shrinkage in cold regions has been linked to climate warming and permafrost thaw. Permafrost aggradation, however, has been observed within the margins of recently receded lakes, in seeming contradiction of climate warming. Here permafrost aggradation dynamics are examined at Twelvemile Lake, a retreating lake in interior Alaska. Observations reveal patches of recently formed permafrost within the dried lake margin, colocated with discrete bands of willow shrub. We test ecological succession, which alters shading, infiltration, and heat transport, as the driver of aggradation using numerical simulation of variably saturated groundwater flow and heat transport with phase change (i.e., freeze-thaw). Simulations support permafrost development under current climatic conditions, but only when net effects of vegetation on soil conditions are incorporated, thus pointing to the role of ecological succession. Furthermore, model results indicate that permafrost aggradation is transitory with further climate warming, as new permafrost thaws within seven decades.

  8. Identifying active methane-oxidizers in thawed Arctic permafrost by proteomics

    Science.gov (United States)

    Lau, C. M.; Stackhouse, B. T.; Chourey, K.; Hettich, R. L.; Vishnivetskaya, T. A.; Pfiffner, S. M.; Layton, A. C.; Mykytczuk, N. C.; Whyte, L.; Onstott, T. C.

    2012-12-01

    The rate of CH4 release from thawing permafrost in the Arctic has been regarded as one of the determining factors on future global climate. It is uncertain how indigenous microorganisms would interact with such changing environmental conditions and hence their impact on the fate of carbon compounds that are sequestered in the cryosol. Multitudinous studies of pristine surface cryosol (top 5 cm) and microcosm experiments have provided growing evidence of effective methanotrophy. Cryosol samples corresponding to active layer were sampled from a sparsely vegetated, ice-wedge polygon at the McGill Arctic Research Station at Axel Heiberg Island, Nunavut, Canada (N79°24, W90°45) before the onset of annual thaw. Pyrosequencing of 16S rRNA gene indicated the occurrence of methanotroph-containing bacterial families as minor components (~5%) in pristine cryosol including Bradyrhizobiaceae, Methylobacteriaceae and Methylocystaceae within alpha-Proteobacteria, and Methylacidiphilaceae within Verrucomicrobia. The potential of methanotrophy is supported by preliminary analysis of metagenome data, which indicated putative methane monooxygenase gene sequences relating to Bradyrhizobium sp. and Pseudonocardia sp. are present. Proteome profiling in general yielded minute traces of proteins, which likely hints at dormant nature of the soil microbial consortia. The lack of specific protein database for permafrost posted additional challenge to protein identification. Only 35 proteins could be identified in the pristine cryosol and of which 60% belonged to Shewanella sp. Most of the identified proteins are known to be involved in energy metabolism or post-translational modification of proteins. Microcosms amended with sodium acetate exhibited a net methane consumption of ~65 ngC-CH4 per gram (fresh weight) of soil over 16 days of aerobic incubation at room temperature. The pH in microcosm materials remained acidic (decreased from initial 4.7 to 4.5). Protein extraction and

  9. Landscape and Hydrological Transformation in the Canadian High Arctic: Climate Change and Permafrost Degradation As Drivers of Change

    Science.gov (United States)

    Lamoureux, S. F.; Lafreniere, M. J.

    2014-12-01

    Recent climate warming and landscape instability arising from permafrost degradation in the Canadian High Arctic have resulted in significant changes to the hydrological system. We have undertaken an integrated watershed and permafrost research program at the Cape Bounty Arctic Watershed Observatory (75°N, 109°W) in paired watershed-lake systems to assess the impact of these changes. Research has captured hydrological changes resulting from exceptional warmth, and permafrost degradation and disturbance. Results highlight the contrasting effect of thermal (deeper soil thaw) versus physical perturbation (slope failures and permafrost degradation). Thermal perturbation applies to most of the landscape, and results indicate that ground ice melt alters flow and mobilizes solutes for a number of years following a single warm year. These effects are measureable at the slope-catchment scale, especially during baseflow. By contrast, physical disturbance is highly localized and produces high sediment and particulate carbon erosion from slopes, but downstream particulate delivery is dependent on surface connectivity. Recovery from disturbances appears to occur rapidly, and continued geomorphic change and new slope channels result in sustained delivery of particulates to channels. The result is increased long term landscape heterogeneity with respect to erosion compared to the pre-disturbance condition. Downstream channel response to particulate loading further dampens the response to physical disturbance through channel storage of material. Hence, at the larger watershed scale, the effect of physical perturbation is minimal in the initial years of recovery. These results point to a landscape that has been substantially impacted by recent hydrological and permafrost changes. Understanding and distinguishing these impacts provides a basis for systematically evaluating biogeochemical cycling and ecosystem responses in aquatic settings.

  10. The Role of Explicitly Modeling Bryophytes in Simulating Carbon Exchange and Permafrost Dynamics of an Arctic Coastal Tundra at Barrow, Alaska

    Science.gov (United States)

    Yuan, F.; Thornton, P. E.; McGuire, A. D.; Oechel, W. C.; Yang, B.; Tweedie, C. E.; Rogers, A.; Norby, R. J.

    2013-12-01

    Bryophyte cover is greater than 50% in many Arctic tundra ecosystems. In regions of the Arctic where shrubs are expanding it is expected that bryophyte cover will be substantially reduced. Such a loss in cover could influence the hydrological, biogeochemical, and permafrost dynamics of Arctic tundra ecosystems. The explicit representation of bryophyte physiological and biophysical processes in large-scale ecological and land surface models is rare, and we hypothesize that the representation of bryophytes has consequences for estimates of the exchange of water, energy, and carbon by these models. This study explicitly represents the effects of bryophyte function and structure on the exchange of carbon (e.g., summer photosynthesis effects) and energy (e.g., summer insulation effects) with the atmosphere in the Community Land Model (CLM-CN). The modified model was evaluated for its ability to simulate C exchange, soil temperature, and soil moisture since the 1970s at Barrow, Alaska through comparison with data from AmeriFlux sites, USDA Soil Climate Networks observation sites at Barrow, and other sources. We also compare the outputs of the CLM-CN simulations with those of the recently developed Dynamical Organic Soil coupled Terrestrial Ecosystem Model (DOS-TEM). Overall, our evaluation indicates that bryophytes are important contributors to land-atmospheric C exchanges in Arctic tundra and that they play an important role to permafrost thermal and hydrological processes which are critical to permafrost stability. Our next step in this study is to examine the climate system effects of explicitly representing bryophyte dynamics in the land surface model. Key Words: Bryophytes, Arctic coastal tundra, Vegetation composition, Net Ecosystem Exchange, Permafrost, Land Surface Model, Terrestrial Ecosystem Model

  11. Relationship between Methane Content in Siberian Permafrost and Soil Properties

    Science.gov (United States)

    Brouchkov, A.; Fukuda, M.

    2004-05-01

    Methane is one of the greenhouse gases among other gases, and it is important to identify sources of methane. Permafrost deposits in Siberia contain large amounts of methane in air bubbles, and there is a high possibility of permafrost thawing due to climatic warming. However, distribution of methane in frozen deposits is still poorly known. It should be related to soil content and properties. Therefore, present knowledge of permafrost soils collected by a number of studies can be a key to understanding of methane distribution; the subject was never discussed before. Air bubbles from frozen soil and ice were sampled at the uppermost layers of permafrost from the depth up to 5 and more m in Eastern Siberia. The major study site was located in valley of Lena River. The permafrost samples were obtained by shallow borehole drilling. Soil composition, density and water content were also measured as well as the concentration of gases in the air bubbles. Total number of air samples was about 200. Air from soils was analyzed by gas chromatograph. No certain relationship between methane concentration and depth was found. Highly concentrated methane occurs in permafrost at different depths. Ice wedges contain less methane than frozen soils in general. There no obvious tendencies between water contents and values of concentrations of both methane and carbon dioxide were found. Methane content increases in general with water content increase, and carbon dioxide content becomes lower; however, in some cases the tendency is opposite, if the concentration is high (up to 70 ppt). Data collected on ion (salt) content is limited, but methane content rises with salinization increase. Low methane content and low salinization in the same time could be connected to possible thawing of permafrost when soil could be washed. Frozen soils containing large amounts of methane and being thawed have average pH about 7-9. The more density and age of frozen soil the more methane content; it could

  12. Dissolved organic matter composition of Arctic rivers: Linking permafrost and parent material to riverine carbon

    Science.gov (United States)

    O'Donnell, Jonathan A.; Aiken, George R.; Swanson, David K.; Panda, Santosh; Butler, Kenna D.; Baltensperger, Andrew P.

    2016-12-01

    Recent climate change in the Arctic is driving permafrost thaw, which has important implications for regional hydrology and global carbon dynamics. Permafrost is an important control on groundwater dynamics and the amount and chemical composition of dissolved organic matter (DOM) transported by high-latitude rivers. The consequences of permafrost thaw for riverine DOM dynamics will likely vary across space and time, due in part to spatial variation in ecosystem properties in Arctic watersheds. Here we examined watershed controls on DOM composition in 69 streams and rivers draining heterogeneous landscapes across a broad region of Arctic Alaska. We characterized DOM using bulk dissolved organic carbon (DOC) concentration, optical properties, and chemical fractionation and classified watersheds based on permafrost characteristics (mapping of parent material and ground ice content, modeling of thermal state) and ecotypes. Parent material and ground ice content significantly affected the amount and composition of DOM. DOC concentrations were higher in watersheds underlain by fine-grained loess compared to watersheds underlain by coarse-grained sand or shallow bedrock. DOC concentration was also higher in rivers draining ice-rich landscapes compared to rivers draining ice-poor landscapes. Similarly, specific ultraviolet absorbance (SUVA254, an index of DOM aromaticity) values were highest in watersheds underlain by fine-grained deposits or ice-rich permafrost. We also observed differences in hydrophobic organic acids, hydrophilic compounds, and DOM fluorescence across watersheds. Both DOC concentration and SUVA254 were negatively correlated with watershed active layer thickness, as determined by high-resolution permafrost modeling. Together, these findings highlight how spatial variations in permafrost physical and thermal properties can influence riverine DOM.

  13. Nutrient Limitation of Microbial Mediated Decomposition and Arctic Soil Chronology

    Science.gov (United States)

    Melle, C. J.; Darrouzet-Nardi, A.; Wallenstein, M. D.

    2012-12-01

    Soils of northern permafrost regions currently contain twice as much carbon as the entire Earth's atmosphere. Traditionally, environmental constraints have limited microbial activity resulting in restricted decomposition of soil organic matter in these systems and accumulation of massive amounts of soil organic carbon (SOC), however climate change is reducing the constraints of decomposition in arctic permafrost regions. Carbon cycling in nutrient poor, arctic ecosystems is tightly coupled to other biogeochemical cycles. Several studies have suggested strong nitrogen limitations of primary productivity and potentially warm-season microbial activity in these nutrient deficient soils. Nitrogen is required for microbial extracellular enzyme production which drives the decomposition of soil organic matter (SOM). Nitrogen limited arctic soils may also experience limitation via labile carbon availability despite the SOM rich environment due to low extracellular enzyme production. Few studies have directly addressed nutrient induced microbial limitation in SOC rich arctic tundra soils, and even less is known about the potential for nutrient co-limitation. Additionally, through the process of becoming deglaciated, sites within close proximity to one another may have experienced drastic differences in their effective soil ages due to the varied length of their active histories. Many soil properties and nutrient deficiencies are directly related to soil age, however this chronology has not previously been a focus of research on nutrient limitation of arctic soil microbial activity. Understanding of nutrient limitations, as well as potential co-limitation, on arctic soil microbial activity has important implications for carbon cycling and the ultimate fate of the current arctic SOC reservoir. Analyses of nutrient limitation on soils of a single site are not adequate for fully understanding the controls on soil microbial activity across a vast land mass with large variation in

  14. The Influence of Vegetation Canopy Structure on Active Layer Thaw Within the Sub-Arctic Discontinuous Permafrost Zone

    Science.gov (United States)

    Chasmer, L.; Quinton, W.; Hopkinson, C.; Petrone, R.; Whittington, P.

    2009-05-01

    Much of the sub-arctic discontinuous permafrost zone is dominated by a range in peatland ecosystems, each with their own characteristic soil frost dynamics. Soil thaw within the discontinuous permafrost zones of the Canadian sub-arctic is driven by the surface energy balance. The following study examines the influence of canopy structure on frost table (FT) depth and rates of thaw by: 1. relating measurements of FT depth to canopy structure using airborne scanning light detection and ranging (lidar) and hemispherical photographs taken below vegetated canopies; and 2. quantifying the spatial influences of canopy structural characteristics on the radiation balance (direct and diffuse incident radiation) within raised peat plateaus, connected bogs, fens, and isolated bogs. The results of this study indicate that peat plateaus, being characterised by greater vegetation fractional cover, typically have shallower FT depths (r2 = 0.5, p = 0.03) than locations with lower biomass. Further, average ground surface elevation and canopy height are related to rates of FT thaw (r2 = 0.73, p indicates that rates of thaw at the edges of peat plateaus and areas surrounding isolated bogs will be exacerbated by increased incident radiation and less shadowing by the canopy, leading to the conversion of peat plateaus to fens or bogs. This hypothesis is tested by comparing the change in peat plateau area coverage in 2000 and 2008 using classified IKONOS imagery (2000) and airborne lidar (2008).

  15. Arctic cities and climate change: climate-induced changes in stability of Russian urban infrastructure built on permafrost

    Science.gov (United States)

    Shiklomanov, Nikolay; Streletskiy, Dmitry; Swales, Timothy

    2014-05-01

    Planned socio-economic development during the Soviet period promoted migration into the Arctic and work force consolidation in urbanized settlements to support mineral resources extraction and transportation industries. These policies have resulted in very high level of urbanization in the Soviet Arctic. Despite the mass migration from the northern regions during the 1990s following the collapse of the Soviet Union and the diminishing government support, the Russian Arctic population remains predominantly urban. In five Russian Administrative regions underlined by permafrost and bordering the Arctic Ocean 66 to 82% (depending on region) of the total population is living in Soviet-era urban communities. The political, economic and demographic changes in the Russian Arctic over the last 20 years are further complicated by climate change which is greatly amplified in the Arctic region. One of the most significant impacts of climate change on arctic urban landscapes is the warming and degradation of permafrost which negatively affects the structural integrity of infrastructure. The majority of structures in the Russian Arctic are built according to the passive principle, which promotes equilibrium between the permafrost thermal regime and infrastructure foundations. This presentation is focused on quantitative assessment of potential changes in stability of Russian urban infrastructure built on permafrost in response to ongoing and future climatic changes using permafrost - geotechnical model forced by GCM-projected climate. To address the uncertainties in GCM projections we have utilized results from 6 models participated in most recent IPCC model inter-comparison project. The analysis was conducted for entire extent of Russian permafrost-affected area and on several representative urban communities. Our results demonstrate that significant observed reduction in urban infrastructure stability throughout the Russian Arctic can be attributed to climatic changes and that

  16. Effects of permafrost aggradation on peat properties as determined from a pan-Arctic synthesis of plant macrofossils

    Science.gov (United States)

    Treat, C.C.; Jones, Miriam C.; Camill, P.; Gallego-Sala, A.; Garneau, M.; Harden, Jennifer W.; Hugelius, G.; Klein, E.S.; Kokfelt, U.; Kuhry, P.; Loisel, J.; Mathijssen, J.H.; O'Donnell, J.A.; Oksanen, P.O.; Ronkainen, T.M.; Sannel, A.B.K.; Talbot, J. J.; Tarnocal, C.M.; Valiranta, M.

    2016-01-01

    Permafrost dynamics play an important role in high-latitude peatland carbon balance and are key to understanding the future response of soil carbon stocks. Permafrost aggradation can control the magnitude of the carbon feedback in peatlands through effects on peat properties. We compiled peatland plant macrofossil records for the northern permafrost zone (515 cores from 280 sites) and classified samples by vegetation type and environmental class (fen, bog, tundra and boreal permafrost, and thawed permafrost). We examined differences in peat properties (bulk density, carbon (C), nitrogen (N) and organic matter content, and C/N ratio) and C accumulation rates among vegetation types and environmental classes. Consequences of permafrost aggradation differed between boreal and tundra biomes, including differences in vegetation composition, C/N ratios, and N content. The vegetation composition of tundra permafrost peatlands was similar to permafrost-free fens, while boreal permafrost peatlands more closely resembled permafrost-free bogs. Nitrogen content in boreal permafrost and thawed permafrost peatlands was significantly lower than in permafrost-free bogs despite similar vegetation types (0.9% versus 1.5% N). Median long-term C accumulation rates were higher in fens (23 g C m−2 yr−1) than in permafrost-free bogs (18 g C m−2 yr−1) and were lowest in boreal permafrost peatlands (14 g C m−2 yr−1). The plant macrofossil record demonstrated transitions from fens to bogs to permafrost peatlands, bogs to fens, permafrost aggradation within fens, and permafrost thaw and reaggradation. Using data synthesis, we have identified predominant peatland successional pathways, changes in vegetation type, peat properties, and C accumulation rates associated with permafrost aggradation.

  17. Changing Arctic ecosystems: sea ice decline, permafrost thaw, and benefits for geese

    Science.gov (United States)

    Flint, Paul; Whalen, Mary; Pearce, John M.

    2014-01-01

    Through the Changing Arctic Ecosystems (CAE) initiative, the U.S. Geological Survey (USGS) strives to inform resource management decisions for Arctic Alaska by providing scientific information on current and future ecosystem response to a warming climate. A key area for the USGS CAE initiative has been the Arctic Coastal Plain of northern Alaska. This region has experienced a warming trend over the past 30 years, leading to reductions in sea ice and thawing of permafrost. Loss of sea ice has increased ocean wave action, leading to erosion and salt water inundation of coastal habitats. Saltwater tolerant plants are now thriving in these areas and this appears to be a positive outcome for geese in the Arctic. This finding is contrary to the deleterious effects that declining sea ice is having on habitats of ice-dependent animals, such as polar bear and walrus.

  18. Pan-Arctic ice-wedge degradation in warming permafrost and its influence on tundra hydrology

    Science.gov (United States)

    Liljedahl, Anna K.; Boike, Julia; Daanen, Ronald P.; Fedorov, Alexander N.; Frost, Gerald V.; Grosse, Guido; Hinzman, Larry D.; Iijma, Yoshihiro; Jorgenson, Janet C.; Matveyeva, Nadya; Necsoiu, Marius; Raynolds, Martha K.; Romanovsky, Vladimir E.; Schulla, Jörg; Tape, Ken D.; Walker, Donald A.; Wilson, Cathy J.; Yabuki, Hironori; Zona, Donatella

    2016-04-01

    Ice wedges are common features of the subsurface in permafrost regions. They develop by repeated frost cracking and ice vein growth over hundreds to thousands of years. Ice-wedge formation causes the archetypal polygonal patterns seen in tundra across the Arctic landscape. Here we use field and remote sensing observations to document polygon succession due to ice-wedge degradation and trough development in ten Arctic localities over sub-decadal timescales. Initial thaw drains polygon centres and forms disconnected troughs that hold isolated ponds. Continued ice-wedge melting leads to increased trough connectivity and an overall draining of the landscape. We find that melting at the tops of ice wedges over recent decades and subsequent decimetre-scale ground subsidence is a widespread Arctic phenomenon. Although permafrost temperatures have been increasing gradually, we find that ice-wedge degradation is occurring on sub-decadal timescales. Our hydrological model simulations show that advanced ice-wedge degradation can significantly alter the water balance of lowland tundra by reducing inundation and increasing runoff, in particular due to changes in snow distribution as troughs form. We predict that ice-wedge degradation and the hydrological changes associated with the resulting differential ground subsidence will expand and amplify in rapidly warming permafrost regions.

  19. Temperature Effects on Microbial CH4 and CO2 Production in Permafrost-Affected Soils From the Barrow Environmental Observatory

    Science.gov (United States)

    Graham, D. E.; Roy Chowdhury, T.; Zheng, J.; Moon, J. W.; Yang, Z.; Gu, B.; Wullschleger, S. D.

    2015-12-01

    Warmer Arctic temperatures are increasing the annual soil thaw depth and prolonging the thaw season in Alaskan permafrost zones. This change exposes organic matter buried in the soils and permafrost to microbial degradation and mineralization to form CO2 and CH4. The proportion and fluxes of these greenhouse gases released into the atmosphere control the global feedback on warming. To improve representations of these biogeochemical processes in terrestrial ecosystem models we compared soil properties and microbial activities in core samples of polygonal tundra from the Barrow Environmental Observatory. Measurements of soil water potential through the soil column characterized water binding to the organic and mineral components. This suction combines with temperature to control freezing, gas diffusion and microbial activity. The temperature-dependence of CO2 and CH4 production from anoxic soil incubations at -2, +4 or +8 °C identified a significant lag in methanogenesis relative to CO2 production by anaerobic respiration and fermentation. Changes in the abundance of methanogen signature genes during incubations indicate that microbial population shifts caused by thawing and warmer temperatures drive changes in the mixtures of soil carbon degradation products. Comparisons of samples collected across the microtopographic features of ice-wedge polygons address the impacts of water saturation, iron reduction and organic matter content on CH4 production and oxidation. These combined measurements build process understanding that can be applied across scales to constrain key response factors in models that address Arctic soil warming.

  20. Archaeal communities of Arctic methane-containing permafrost.

    Science.gov (United States)

    Shcherbakova, Victoria; Yoshimura, Yoshitaka; Ryzhmanova, Yana; Taguchi, Yukihiro; Segawa, Takahiro; Oshurkova, Victoria; Rivkina, Elizaveta

    2016-10-01

    In the present study, we used culture-independent methods to investigate the diversity of methanogenic archaea and their distribution in five permafrost samples collected from a borehole in the Kolyma River Lowland (north-east of Russia). Total DNA was extracted from methane-containing permafrost samples of different age and amplified by PCR. The resulting DNA fragments were cloned. Phylogenetic analysis of the sequences showed the presence of archaea in all studied samples; 60%-95% of sequences belonged to the Euryarchaeota. Methanogenic archaea were novel representatives of Methanosarcinales, Methanomicrobiales, Methanobacteriales and Methanocellales orders. Bathyarchaeota (Miscellaneous Crenarchaeota Group) representatives were found among nonmethanogenic archaea in all the samples studied. The Thaumarchaeota representatives were not found in the upper sample, whereas Woesearchaeota (formerly DHVEG-6) were found in the three deepest samples. Unexpectedly, the greatest diversity of archaea was observed at a depth of 22.3 m, probably due to the availability of the labile organic carbon and/or due to the migration of the microbial cells during the freezing front towards the bottom.

  1. 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.

  2. Geologic methane seeps along boundaries of Arctic permafrost thaw and melting glaciers

    Science.gov (United States)

    Walter Anthony, Katey M.; Anthony, Peter; Grosse, Guido; Chanton, Jeffrey

    2012-06-01

    Methane, a potent greenhouse gas, accumulates in subsurface hydrocarbon reservoirs, such as coal beds and natural gas deposits. In the Arctic, permafrost and glaciers form a `cryosphere cap' that traps gas leaking from these reservoirs, restricting flow to the atmosphere. With a carbon store of over 1,200Pg, the Arctic geologic methane reservoir is large when compared with the global atmospheric methane pool of around 5Pg. As such, the Earth's climate is sensitive to the escape of even a small fraction of this methane. Here, we document the release of 14C-depleted methane to the atmosphere from abundant gas seeps concentrated along boundaries of permafrost thaw and receding glaciers in Alaska and Greenland, using aerial and ground surface survey data and in situ measurements of methane isotopes and flux. We mapped over 150,000 seeps, which we identified as bubble-induced open holes in lake ice. These seeps were characterized by anomalously high methane fluxes, and in Alaska by ancient radiocarbon ages and stable isotope values that matched those of coal bed and thermogenic methane accumulations. Younger seeps in Greenland were associated with zones of ice-sheet retreat since the Little Ice Age. Our findings imply that in a warming climate, disintegration of permafrost, glaciers and parts of the polar ice sheets could facilitate the transient expulsion of 14C-depleted methane trapped by the cryosphere cap.

  3. 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.

  4. Permafrost: It's a gas

    Science.gov (United States)

    Christensen, Torben R.

    2016-09-01

    Climate change is causing widespread permafrost thaw in the Arctic. Measurements at 33 Arctic lakes show that old carbon from thawing permafrost is being emitted as methane, though emission rates have not changed during the past 60 years.

  5. Slope Edge Deformation and Permafrost Dynamics Along the Arctic Shelf Edge, Beaufort Sea, Canada

    Science.gov (United States)

    Paull, C. K.; Dallimore, S.; Caress, D. W.; Gwiazda, R.; Lundsten, E. M.; Anderson, K.; Riedel, M.; Melling, H.

    2015-12-01

    The shelf of the Canadian Beaufort Sea is underlain by relict offshore permafrost that formed in the long intervals of terrestrial exposure during glacial periods. At the shelf edge the permafrost thins rapidly and also warms. This area has a very distinct morphology that we attribute to both the formation and degradation of ice bearing permafrost. Positive relief features include circular to oval shaped topographic mounds, up to 10 m high and ~50 m in diameter which occur at a density of ~6 per km2. Intermixed are circular topographic depressions up to 20 m deep. This topography was investigated using an autonomous underwater vehicle that provides 1 m horizontal resolution bathymetry and chirp profiles, a remotely operated vehicle to document seafloor textures, and sediment cores to sample pore waters. A consistent down-core freshening at rates of 14 to 96 mM Cl- per meter was found in these pore waters near the shelf edge. Downward extrapolation of these trends indicates water with ≤335 mM Cl- should occur at 2.3 to 22.4 m sub-seafloor depths within this shelf edge deformation band. Pore water with 335 mM Cl- or less freezes at -1.4°C. As bottom water temperatures in this area are persistently (<-1.4°C) cold and ground ice was observed in some core samples, we interpret the volume changes associated with mound formation are in part due to pore water freezing. Thermal models (Taylor et al., 2014) predict brackish water along the shelf edge may be sourced in relict permafrost melting under the adjacent continental shelf. Buoyant brackish water is hypothesized to migrate along the base of the relict permafrost, to emerge at the shelf edge and then refreeze when it encounters the colder seafloor. Expansion generated by the formation of ice-bearing permafrost generates the positive relief mounds and ridges. The associated negative relief features may be related to permafrost dynamics also. Permafrost dynamics may have geohazard implications that are unique to the

  6. Modeling the evolution of climate-sensitive Arctic subsea permafrost in regions of extensive gas expulsion at the West Yamal shelf

    Science.gov (United States)

    Portnov, Alexey; Mienert, Jurgen; Serov, Pavel

    2014-11-01

    Thawing subsea permafrost controls methane release from the Russian Arctic shelf having a considerable impact on the climate-sensitive Arctic environment. Expulsions of methane from shallow Russian Arctic shelf areas may continue to rise in response to intense degradation of relict subsea permafrost. Here we show modeling of the permafrost evolution from the Late Pleistocene to present time at the West Yamal shelf. Modeling results suggest a highly dynamic permafrost system that directly responds to even minor variations of lower and upper boundary conditions, e.g., geothermal heat flux from below and/or bottom water temperature changes from above permafrost. Scenarios of permafrost evolution show a potentially nearest landward modern extent of the permafrost at the West Yamal shelf limited by ~17 m isobaths, whereas its farthest seaward extent coincides with ~100 m isobaths. The model also predicts seaward tapering of relict permafrost with a maximal thickness of 275-390 m near the shoreline. Previous field observations detected extensive emissions of free gas into the water column at the transition zone between today's shallow water permafrost (20 m). The model adapts well to corresponding heat flux and ocean temperature data, providing crucial information about the modern permafrost conditions. It shows current locations of upper and lower permafrost boundaries and evidences for possible release of methane from the seabed to the hydrosphere in a warming Arctic.

  7. Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

    Directory of Open Access Journals (Sweden)

    Corina Dörfer

    Full Text Available The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA and continuous permafrost (site Wudaoliang, WUD. Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (1.6 g cm(-3 of mineral associated organic matter (MOM. The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1. Higher SOC contents (320 g kg(-1 were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1. Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA and 22% (WUD to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth account for 10.4 kg m(-2, compared to 3.4 kg m(-2 in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

  8. Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

    Science.gov (United States)

    Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

    2013-01-01

    The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (organic matter (FPOM) and occluded particulate organic matter (OPOM), plus a heavy fraction (>1.6 g cm(-3)) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1). Higher SOC contents (320 g kg(-1)) were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1)). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth) account for 10.4 kg m(-2), compared to 3.4 kg m(-2) in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

  9. Radiation budget and soil heat fluxes in different Arctic tundra vegetation types

    Science.gov (United States)

    Juszak, Inge; Iturrate Garcia, Maitane; Gastellu-Etchegorry, Jean-Philippe; Schaepman, Michael E.; Schaepman-Strub, Gabriela

    2016-04-01

    While solar radiation is one of the primary energy sources for warming and thawing permafrost soil, the amount of shortwave radiation reaching the soil is reduced by vegetation shading. Climate change has led to greening, shrub expansion and encroachment in many Arctic tundra regions and further changes are anticipated. These vegetation changes feed back to the atmosphere and permafrost as they modify the surface energy budget. However, canopy transmittance of solar radiation has rarely been measured or modelled for a variety of tundra vegetation types. We assessed the radiation budget of the most common vegetation types at the Kytalyk field site in North-East Siberia (70.8°N, 147.5°E) with field measurements and 3D radiative transfer modelling and linked it to soil heat fluxes. Our results show that Arctic tundra vegetation types differ in canopy albedo and transmittance as well as in soil heat flux and active layer thickness. Tussock sedges transmitted on average 56% of the incoming light and dwarf shrubs 27%. For wet sedges we found that the litter layer was very important as it reduced the average transmittance to only 6%. Model output indicated that both, albedo and transmittance, also depend on the spatial aggregation of vegetation types. We found that permafrost thaw was more strongly related to soil properties than to canopy shading. The presented radiative transfer model allows quantifying effects of the vegetation layer on the surface radiation budget in permafrost areas. The parametrised model can account for diverse vegetation types and variation of properties within types. Our results highlight small scale radiation budget and permafrost thaw variability which are indicated and partly caused by vegetation. As changes in species composition and biomass increase can influence thaw rates, small scale patterns should be considered in assessments of climate-vegetation-permafrost feedbacks.

  10. Chemical indicators of cryoturbation and microbial processing throughout an alaskan permafrost soil depth profile

    Science.gov (United States)

    Although permafrost soils contain vast stores of carbon, we know relatively little about the chemical composition of their constituent organic matter. Soil organic matter chemistry is an important predictor of decomposition rates, especially in the initial stages of decomposition. Permafrost, organi...

  11. A pan-Arctic synthesis of CH4 and CO2 production from anoxic soil incubations

    Science.gov (United States)

    Treat, C.C.; Natali, Susan M.; Ernakovich, Jessica; Iverson, Colleen M.; Lupasco, Massimo; McGuire, Anthony; Norby, Richard J.; Roy Chowdhury, Taniya; Richter, Andreas; Šantrůčková, Hana; Schädel, C.; Schuur, Edward A.G.; Sloan, Victoria L.; Turetsky, Merritt R.; Waldrop, Mark P.

    2015-01-01

    Permafrost thaw can alter the soil environment through changes in soil moisture, frequently resulting in soil saturation, a shift to anaerobic decomposition, and changes in the plant community. These changes, along with thawing of previously frozen organic material, can alter the form and magnitude of greenhouse gas production from permafrost ecosystems. We synthesized existing methane (CH4) and carbon dioxide (CO2) production measurements from anaerobic incubations of boreal and tundra soils from the geographic permafrost region to evaluate large-scale controls of anaerobic CO2 and CH4 production and compare the relative importance of landscape-level factors (e.g., vegetation type and landscape position), soil properties (e.g., pH, depth, and soil type), and soil environmental conditions (e.g., temperature and relative water table position). We found fivefold higher maximum CH4 production per gram soil carbon from organic soils than mineral soils. Maximum CH4 production from soils in the active layer (ground that thaws and refreezes annually) was nearly four times that of permafrost per gram soil carbon, and CH4 production per gram soil carbon was two times greater from sites without permafrost than sites with permafrost. Maximum CH4 and median anaerobic CO2 production decreased with depth, while CO2:CH4 production increased with depth. Maximum CH4 production was highest in soils with herbaceous vegetation and soils that were either consistently or periodically inundated. This synthesis identifies the need to consider biome, landscape position, and vascular/moss vegetation types when modeling CH4 production in permafrost ecosystems and suggests the need for longer-term anaerobic incubations to fully capture CH4 dynamics. Our results demonstrate that as climate warms in arctic and boreal regions, rates of anaerobic CO2 and CH4 production will increase, not only as a result of increased temperature, but also from shifts in vegetation and increased

  12. Autotrophic and heterotrophic components of soil respiration in permafrost zone.

    Science.gov (United States)

    Udovenko, Maria; Goncharova, Olga

    2016-04-01

    Soil carbon dioxide emissions production is an important integral indicator of soil biological activity and it includes several components: the root respiration and microbial decomposition of organic matter. Separate determination of the components of soil respiration is necessary for studying the balance of carbon in the soil and to assessment its potential as a sink or source of carbon dioxide. The aim of this study was testing field methods of separate determination of root and microbial respiration in soils of north of West Siberia. The research took place near the town Nadym, Yamalo-Nenets Autonomous District (north of West Siberia).The study area was located in the northern taiga with sporadic permafrost. Investigations were carried out at two sites: in forest and in frozen peatland. 3 methods were tested for the separation of microbial and root respiration. 1) "Shading"; 2) "Clipping"(removing the above-ground green plant parts); 3)a modified method of roots exclusion (It is to compare the emission of soils of "peat spots", devoid of vegetation and roots, and soils located in close proximity to the spots on which there is herbaceous vegetation and moss). For the experiments on methods of "Shading" and "Clipping" in the forest and on the frozen peatland ware established 12 plots, 1 x 1 m (3 plots in the forest and at 9 plots on frozen peatland; 4 of them - control).The criterions for choosing location sites were the similarity of meso- and microrelief, the same depth of permafrost, the same vegetation. Measurement of carbon dioxide emissions (chamber method) was carried out once a day, in the evening, for a week. Separation the root and microbial respiration by "Shading" showed that in the forest the root respiration contribution is 5%, and microbial - 95%. On peatlands root respiration is 41%, 59% of the microbial. In the experiment "Clipping" in peatlands root respiration is 56%, the microbial respiration - 44%, in forest- root respiration is 17%, and

  13. Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes

    Science.gov (United States)

    Arp, Christopher D.; Whitman, Matthew S.; Jones, Benjamin M.; Grosse, Guido; Gaglioti, Benjamin V.; Heim, Kurt C.

    2015-01-01

    Beaded streams are widespread in permafrost regions and are considered a common thermokarst landform. However, little is known about their distribution, how and under what conditions they form, and how their intriguing morphology translates to ecosystem functions and habitat. Here we report on a Circum-Arctic survey of beaded streams and a watershed-scale analysis in northern Alaska using remote sensing and field studies. We mapped over 400 channel networks with beaded morphology throughout the continuous permafrost zone of northern Alaska, Canada, and Russia and found the highest abundance associated with medium- to high- ground ice content permafrost in moderately sloping terrain. In the Fish Creek watershed, beaded streams accounted for half of the drainage density, occurring primarily as low-order channels initiating from lakes and drained lake basins. Beaded streams predictably transition to alluvial channels with increasing drainage area and decreasing channel slope, although this transition is modified by local controls on water and sediment delivery. Comparison of one beaded channel using repeat photography between 1948 and 2013 indicate a relatively stable landform and 14C dating of basal sediments suggest channel formation may be as early as the Pleistocene-Holocene transition. Contemporary processes, such as deep snow accumulation in riparian zones effectively insulates channel ice and allows for perennial liquid water below most beaded stream pools. Because of this, mean annual temperatures in pool beds are greater than 2°C, leading to the development of perennial thaw bulbs or taliks underlying these thermokarst features. In the summer, some pools thermally stratify, which reduces permafrost thaw and maintains coldwater habitats. Snowmelt generated peak-flows decrease rapidly by two or more orders of magnitude to summer low flows with slow reach-scale velocity distributions ranging from 0.1 to 0.01 m/s, yet channel runs still move water rapidly

  14. 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.

  15. Trace metal distribution in pristine permafrost-affected soils of the Lena River Delta and its Hinterland, Northern Siberia, Russia

    Directory of Open Access Journals (Sweden)

    I. Antcibor

    2013-02-01

    Full Text Available Soils are an important compartment of ecosystems and have the ability to immobilize chemicals preventing their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since the Arctic ecosystems are considered to be very sensitive to climatic changes as well as to chemical contamination. This study characterizes background levels of trace metals in permafrost-affected soils of the Lena River Delta and its hinterland in northern Siberia (73.5° N–69.5° N representing a remote region far from evident anthropogenic trace metal sources. Investigations on total element contents of iron (Fe, arsenic (As, manganese (Mn, zinc (Zn, nickel (Ni, copper (Cu, lead (Pb, cadmium (Cd, cobalt (Co and mercury (Hg in different soil types developed in different geological parent materials have been carried out. The highest concentrations of the majority of the measured elements were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex in the Lena River Delta region. Correlation analyses of trace metal concentrations and soil chemical and physical properties at a Holocene estuarine terrace and two modern floodplain levels in the southern-central Lena River Delta (Samoylov Island showed that the main factors controlling the trace metal distribution in these soils are organic matter content, soil texture and contents of iron and manganese-oxides. Principal Component Analysis (PCA revealed that soil oxides play a significant role in trace metal distribution in both top and bottom horizons. Occurrence of organic matter contributes to Cd binding in top soils and Cu binding in bottom horizons. Observed ranges of the background concentrations of the majority of trace elements were

  16. The growth of shrubs on high Arctic tundra at Bylot Island: impact on snow physical properties and permafrost thermal regime

    Science.gov (United States)

    Domine, Florent; Barrere, Mathieu; Morin, Samuel

    2016-12-01

    With climate warming, shrubs have been observed to grow on Arctic tundra. Their presence is known to increase snow height and is expected to increase the thermal insulating effect of the snowpack. An important consequence would be the warming of the ground, which will accelerate permafrost thaw, providing an important positive feedback to warming. At Bylot Island (73° N, 80° W) in the Canadian high Arctic where bushes of willows (Salix richardsonii Hook) are growing, we have observed the snow stratigraphy and measured the vertical profiles of snow density, thermal conductivity and specific surface area (SSA) in over 20 sites of high Arctic tundra and in willow bushes 20 to 40 cm high. We find that shrubs increase snow height, but only up to their own height. In shrubs, snow density, thermal conductivity and SSA are all significantly lower than on herb tundra. In shrubs, depth hoar which has a low thermal conductivity was observed to grow up to shrub height, while on herb tundra, depth hoar only developed to 5 to 10 cm high. The thermal resistance of the snowpack was in general higher in shrubs than on herb tundra. More signs of melting were observed in shrubs, presumably because stems absorb radiation and provide hotspots that initiate melting. When melting was extensive, thermal conductivity was increased and thermal resistance was reduced, counteracting the observed effect of shrubs in the absence of melting. Simulations of the effect of shrubs on snow properties and on the ground thermal regime were made with the Crocus snow physics model and the ISBA (Interactions between Soil-Biosphere-Atmosphere) land surface scheme, driven by in situ and reanalysis meteorological data. These simulations did not take into account the summer impact of shrubs. They predict that the ground at 5 cm depth at Bylot Island during the 2014-2015 winter would be up to 13 °C warmer in the presence of shrubs. Such warming may however be mitigated by summer effects.

  17. The role of snow cover and soil freeze/thaw cycles affecting boreal-arctic soil carbon dynamics

    Directory of Open Access Journals (Sweden)

    Y. Yi

    2015-07-01

    Full Text Available Northern Hemisphere permafrost affected land areas contain about twice as much carbon as the global atmosphere. This vast carbon pool is vulnerable to accelerated losses through mobilization and decomposition under projected global warming. Satellite data records spanning the past 3 decades indicate widespread reductions (∼ 0.8–1.3 days decade−1 in the mean annual snow cover extent and frozen season duration across the pan-Arctic domain, coincident with regional climate warming trends. How the soil carbon pool responds to these changes will have a large impact on regional and global climate. Here, we developed a coupled terrestrial carbon and hydrology model framework with detailed 1-D soil heat transfer representation to investigate the sensitivity of soil organic carbon stocks and soil decomposition to changes in snow cover and soil freeze/thaw processes in the Pan-Arctic region over the past three decades (1982–2010. Our results indicate widespread soil active layer deepening across the pan-Arctic, with a mean decadal trend of 6.6 ± 12.0 (SD cm, corresponding with widespread warming and lengthening non-frozen season. Warming promotes vegetation growth and soil heterotrophic respiration, particularly within surface soil layers (≤ 0.2 m. The model simulations also show that seasonal snow cover has a large impact on soil temperatures, whereby increases in snow cover promote deeper (≥ 0.5 m soil layer warming and soil respiration, while inhibiting soil decomposition from surface (≤ 0.2 m soil layers, especially in colder climate zones (mean annual T ≤ −10 °C. Our results demonstrate the important control of snow cover in affecting northern soil freeze/thaw and soil carbon decomposition processes, and the necessity of considering both warming, and changing precipitation and snow cover regimes in characterizing permafrost soil carbon dynamics.

  18. Vulnerability of Permafrost Soil Carbon to Climate Warming: Evaluating Controls on Microbial Community Composition

    Science.gov (United States)

    Abstract: Despite the fact that permafrost soils contain up to half of the carbon (C) in terrestrial pools, we have a poor understanding of the controls on decomposition in thawed permafrost. Global climate models assume that decomposition increases linearly with temperature, yet decomposition in th...

  19. Buried glacier ice in permafrost, a window to the past: examples from Bylot Island, Canadian Arctic

    Science.gov (United States)

    Fortier, D.; Coulombe, S.; Kanevskiy, M. Z.; Paquette, M.; Shur, Y.; Stephani, E.

    2011-12-01

    Bylot Island is located north of Baffin Island (73°N, 80°W) and is extensively covered by an ice cap and its outlet glaciers flowing towards the arctic lowland of the Lancaster formation. During summers of 2009 and 2011 several active-layer detachment slides exposed large massive ice bodies and other types of debris-rich ice that were interpreted as buried glacier ice. The upper part of the massive ice and debris-rich ice were usually in contact with various types of ice-contact or glacio-fluvial sediments and in some cases they were covered by mass wasting/colluvial deposits. This suggests that their preservation was likely related to burial of the ice and refreezing of the overlying sediments following permafrost aggradation. A preliminary analysis of the ice facies and ice crystals revealed the presence of four distinct types of ice: 1) clear-ice bodies with very few sediment and no organic inclusions. The ice crystals were large (cm), randomly oriented and air bubbles were observed at the junction of crystals. These characteristics could potentially indicate an englacial (snow-neve metamorphism) origin for these clear ice bodies; 2) large, meter thick, clear ice layers with no sediment, nor organics. The ice crystals were large (cm), several cm long, oriented in the same direction, and vertically aligned. These characteristics could potentially point to water that refroze in a tunnel incised in englacial ice; 3) Successive, mm to cm thick, ice layers, separated by undulating sand and gravel bands also containing cobles to boulder size rock fragments. These characteristics could potentially represent regelation ice formed at the base of glaciers and incorporated to the glacier sole; 4) mm to cm suspended aggregate of fine-grained sediments in clear ice. These micro-suspended and suspended cryostructures were sometimes deformed and aligned in the form of thin (mm) undulating layers. These micro-structures were very similar to basal ice facies, presumably

  20. Microbes residing in young organic rich Alaskan soils contain older carbon than those residing in old mineral high Arctic soils

    Science.gov (United States)

    Ziolkowski, L. A.; Slater, G. F.; Onstott, T. C.; Whyte, L.; Townsend-Small, A.

    2013-12-01

    Arctic soils range from very organic rich to low carbon and mineral-dominated soils. At present, we do not yet fully understand if all carbon in the Arctic is equally vulnerable to mineralization in a warmer climate. Many studies have demonstrated that ancient carbon is respired when permafrost has thawed, yet our understanding of the active layer and permafrost carbon dynamics is still emerging. In an effort to remedy this disconnect between our knowledge of surface fluxes and below ground processes, we used radiocarbon to examine the microbial carbon dynamics in soil cores from organic rich soils near Barrow, Alaska and mineral soils from the Canadian high Arctic. Specifically, we compared the microbial community using lipid biomarkers, the inputs of carbon using n-alkanes and measured the 14C of both the bulk organic carbon and of the microbial lipids. In theory, the microbial lipids (phospholipid fatty acids, PLFA) represent the viable microbial community, as these lipids are hydrolyzed quickly after cell death. Variations in the PLFA distributions suggested that different microbial communities inhabit organic rich Alaskan soils and those of the Canadian high Arctic. When the PLFA concentrations were converted to cellular concentration, they were within the same order of magnitude (1 to 5 x 108 cells/g dry soil) with slightly higher cell concentrations in the organic rich Alaskan soils. When these cellular concentrations were normalized to the organic carbon content, the Canadian high Arctic soils contained a greater proportion of microbes. Although bulk organic carbon 14C of Alaskan soils indicated more recent carbon inputs into the soil than the Canadian high Arctic soils, the 14C of the PLFA revealed the opposite. For corresponding depth horizons, microbes in Alaskan soils were consuming carbon 1000 to 1500 years older than those in the Canadian high Arctic. Differences between the 14C content of bulk organic carbon and the microbial lipids were much smaller

  1. Viable Species of Flamella (Amoebozoa: Variosea) Isolated from Ancient Arctic Permafrost Sediments.

    Science.gov (United States)

    Shmakova, Lyubov; Bondarenko, Natalya; Smirnov, Alexey

    2016-02-01

    Six viable strains of amoebae belonging to the genus Flamella (Amoebozoa, Variosea) were isolated from permafrost sediments sampled in the Russian Arctic region. Two of them are from late Pleistocene permafrost in North-East Siberia, and four--from Holocene and late Pleistocene in North-West Siberia. Light- and electron-microscopic study and molecular phylogeny show that these isolates represent two new species belonging to the genus Flamella. Both species are cyst-forming. This is a remarkable case of high resistance of protozoan cysts, allowing them to survive and recover an amoebae population after a very long, geologically significant period of rest; a "snapshot" of evolution in time. This study directly shows for the first time that amoeba cysts can be conserved not only for years and decades but for many thousand years and then recover, contributing to the formation of an active microbial community. We propose to name the new species as Flamella pleistocenica n.sp. and Flamella beringiania n.sp. Phylogenetic analysis shows that the genus Flamella is a robust and potentially species-rich group of Variosea.

  2. Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic.

    Science.gov (United States)

    Tanski, George; Lantuit, Hugues; Ruttor, Saskia; Knoblauch, Christian; Radosavljevic, Boris; Strauss, Jens; Wolter, Juliane; Irrgang, Anna M; Ramage, Justine; Fritz, Michael

    2017-03-01

    The changing climate in the Arctic has a profound impact on permafrost coasts, which are subject to intensified thermokarst formation and erosion. Consequently, terrestrial organic matter (OM) is mobilized and transported into the nearshore zone. Yet, little is known about the fate of mobilized OM before and after entering the ocean. In this study we investigated a retrogressive thaw slump (RTS) on Qikiqtaruk - Herschel Island (Yukon coast, Canada). The RTS was classified into an undisturbed, a disturbed (thermokarst-affected) and a nearshore zone and sampled systematically along transects. Samples were analyzed for total and dissolved organic carbon and nitrogen (TOC, DOC, TN, DN), stable carbon isotopes (δ(13)C-TOC, δ(13)C-DOC), and dissolved inorganic nitrogen (DIN), which were compared between the zones. C/N-ratios, δ(13)C signatures, and ammonium (NH4-N) concentrations were used as indicators for OM degradation along with biomarkers (n-alkanes, n-fatty acids, n-alcohols). Our results show that OM significantly decreases after disturbance with a TOC and DOC loss of 77 and 55% and a TN and DN loss of 53 and 48%, respectively. C/N-ratios decrease significantly, whereas NH4-N concentrations slightly increase in freshly thawed material. In the nearshore zone, OM contents are comparable to the disturbed zone. We suggest that the strong decrease in OM is caused by initial dilution with melted massive ice and immediate offshore transport via the thaw stream. In the mudpool and thaw stream, OM is subject to degradation, whereas in the slump floor the nitrogen decrease is caused by recolonizing vegetation. Within the nearshore zone of the ocean, heavier portions of OM are directly buried in marine sediments close to shore. We conclude that RTS have profound impacts on coastal environments in the Arctic. They mobilize nutrients from permafrost, substantially decrease OM contents and provide fresh water and nutrients at a point source.

  3. The role of watershed characteristics, permafrost thaw, and wildfire on dissolved organic carbon biodegradability and water chemistry in Arctic headwater streams

    Directory of Open Access Journals (Sweden)

    J. R. Larouche

    2015-03-01

    Full Text Available In the Alaskan Arctic, rapid climate change is increasing the frequency of disturbance including wildfire and permafrost collapse. These pulse disturbances may influence the delivery of dissolved organic carbon (DOC to aquatic ecosystems, however the magnitude of these effects compared to the natural background variability of DOC at the watershed scale is not well known. We measured DOC quantity, composition, and biodegradability from 14 river and stream reaches (watershed sizes ranging from 1.5–167 km2 some of which were impacted by permafrost collapse (thermokarst and fire. We found that region had a significant impact on quantity and biodegradability of DOC, likely driven by landscape and watershed characteristics such as lithology, soil and vegetation type, elevation, and glacial age. However, contrary to our hypothesis, we found that streams disturbed by thermokarst and fire did not contain significantly altered labile DOC fractions compared to adjacent reference waters, potentially due to rapid ecosystem recovery after fire and thermokarst as well as the limited spatial extent of thermokarst. Overall, biodegradable DOC ranged from 4 to 46% and contrary to patterns of DOC biodegradability in large Arctic rivers, seasonal variation in DOC biodegradability showed no clear pattern between sites, potentially related to stream geomorphology and position along the river network. While thermokarst and fire can alter DOC quantity and biodegradability at the scale of the feature, we conclude that tundra ecosystems are resilient to these types of disturbance.

  4. Methane and Root Dynamics in Arctic Soil

    DEFF Research Database (Denmark)

    D'Imperio, Ludovica

    on the global climate. We investigated two aspects of arctic ecosystem dynamics which are not well represented in climatic models: i) soil methane (CH4) oxidation in dry heath tundra and barren soils and ii) root dynamics in wetlands. Field measurements were carried out during the growing season in Disko Island...

  5. THE CURRENT DYNAMICS OF THE SUBMARINE PERMAFROST AND METHANE EMISSION ON THE SHELF OF THE EASTERN ARCTIC SEAS

    Directory of Open Access Journals (Sweden)

    O. A. Anisimov

    2012-01-01

    Full Text Available We study the methane emission over the East Siberian Arctic Shelf (ESAS under the changing sub-aquatic permafrost conditions from the time of inundation 9–6 thousand years BP to present and further until the end of the millennium. The study is based on the full-physics model of hydrothermal regime of soil. Our results indicate that the current elevated methane emission from ESAS is responsible for 0.01 ºС global air temperature rise. Even under the hypothetic climate scenario that overestimates the range of near-bottom water temperature rise, projected by the end of the millennium thawing of the bottom sediments is likely to be about90 mand will thus not reach the upper limit of the methane hydrate stability zone that is located 100–140 munderneath the sea bottom. The results of the study do not support the so called «methane bomb» hypothesis that is widely discussed in the scientific literature and in the media.

  6. Establishing Permafrost Temperature Data Reanalysis

    Science.gov (United States)

    Romanovsky, V. E.; Sazonova, T. S.; Tipenko, G. S.

    2003-12-01

    permafrost temperature data that were obtained during the 1950s and early 1960s by Max Brewer of USGS in Barrow region. Those measurements were of very high quality, with a precision of generally 0.01oC. A specific numerical model for the Barrow permafrost temperature regime was developed in 1997 at the GI Permafrost Lab. The model was calibrated using data from shallow (down to one meter) soil temperatures obtained by Ken Hinkel at a Barrow site with surface conditions similar to the Brewer site. No data from the Brewer sites were used for the calibration. The daily air temperatures and snow cover thickness during the entire period of measurements (1924-2001) at the Barrow meteorological station were used as input data for this calibrated model. As a result, a time series of daily ground temperatures for the depths between 0 and 200 meters were obtained. To compare calculated temperatures with measured data, we used the time interval between September 1951 and October 1952, when weekly measurements were available. The results of this comparison were much better than expected. For the entire period, which covers more than one year, the differences between calculated and measured permafrost temperatures were typically smaller than 0.3oC in the depth interval between 2 and 18 meters. They practically never exceeded 1oC in the upper two meters of soil and permafrost. The same approach of permafrost temperature data reanalysis was used for many other sites in Alaska and in the Russian Arctic and Sub-Arctic. The results of reconstruction of the permafrost temperature dynamics in 20th century and forecasts for the 21st century based on this approach for the Fairbanks, Barrow, Yakutsk, Tiksi, and Vorkuta sites will be presented.

  7. Identifying the main drivers of soil carbon response to climate change in arctic and boreal Alaska.

    Science.gov (United States)

    Genet, H.; McGuire, A. D.; He, Y.; Johnson, K.; Wylie, B. K.; Pastick, N. J.; Zhuang, Q.; Zhu, Z.

    2015-12-01

    Boreal and arctic regions represent the largest reservoir of carbon among terrestrial biomes. Most of this carbon is stored deep in the soil in permafrost where frozen organic matter is protected from decomposition. The vulnerability of soil carbon stocks to a changing climate in high latitudes depends on a number of physical and ecological processes. The importance of these processes in controlling the dynamics of soil carbon stocks vary across regions because of variability in vegetation composition, drainage condition, and permafrost characteristics. To better understand the main drivers of the vulnerability of soil carbon stocks to climate change in Alaska, we ran a process-based ecosystem model, the Terrestrial Ecosystem Model. This model explicitly simulates interactions between the carbon cycle and permafrost dynamics and was coupled with a disturbance model and a model of biogenic methane dynamics to assess historical and projected soil carbon dynamics in Alaska, from 1950 to 2100. The uncertainties related to climate, fire regime and atmospheric CO2projections on soil carbon dynamics were quantified by running simulations using climate projections from 2 global circulation models, 3 fossil fuel emission scenarios and 3 alternative fire management scenarios. During the historical period [1950-2009], soil carbon stocks increased by 4.7 TgC/yr in Alaska. Soil carbon stocks decreased in boreal Alaska due to substantial fire activity in the early 2000's. This loss was offset by carbon accumulation in the arctic. Changes in soil carbon stocks from 2010 to 2099 ranged from 8.9 to 25.6 TgC/yr, depending on the climate projections. Soil carbon accumulation was slower in lowlands than in uplands and slower in the boreal than in the arctic regions because of the negative effect of fire activity on soil carbon stocks. Tundra ecosystems were more vulnerable to carbon loss from fire than forest ecosystems because of a lower productivity. As a result, the increase in

  8. Evaluating climate variables, indexes and thresholds governing Arctic urban sustainability: case study of Russian permafrost regions

    Science.gov (United States)

    Anisimov, O. A.; Kokorev, V.

    2013-12-01

    Addressing Arctic urban sustainability today forces planners to deal with the complex interplay of multiple factors, including governance and economic development, demography and migration, environmental changes and land use, changes in the ecosystems and their services, and climate change. While the latter can be seen as a factor that exacerbates the existing vulnerabilities to other stressors, changes in temperature, precipitation, snow, river and lake ice, and the hydrological regime also have direct implications for the cities in the North. Climate change leads to reduced demand for heating energy, on one hand, and heightened concerns about the fate of the infrastructure built upon thawing permafrost, on the other. Changes in snowfall are particularly important and have direct implications for the urban economy, as together with heating costs, expenses for snow removal from streets, airport runways, roofs and ventilation corridors underneath buildings erected on pile foundations on permafrost constitute the bulk of the city's maintenance budget. Many cities are located in river valleys and are prone to flooding that leads to enormous economic losses and casualties, including human deaths. The severity of the northern climate has direct implications for demographic changes governed by regional migration and labor flows. Climate could thus be viewed as an inexhaustible public resource that creates opportunities for sustainable urban development. Long-term trends show that climate as a resource is becoming more readily available in the Russian North, notwithstanding the general perception that globally climate change is one of the challenges facing humanity in the 21st century. In this study we explore the sustainability of the Arctic urban environment under changing climatic conditions. We identify key governing variables and indexes and study the thresholds beyond which changes in the governing climatic parameters have significant impact on the economy

  9. Molecular profiling of permafrost soil organic carbon composition and degradation

    Science.gov (United States)

    Gu, B.; Mann, B.

    2014-12-01

    Microbial degradation of soil organic matter (SOM) is a key process for terrestrial carbon (C) cycling, though the dynamics of these transformations remain unclear at the molecular level. This study reports the application of ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) to profile molecular components of Arctic SOM collected from the surface water and the mineral horizon of a low-centered polygon soil at Barrow Environmental Observatory (BEO), Barrow, Alaska. Soil samples were subjected to anaerobic warming experiments for a period of 40 days, and the SOM was extracted before and after the incubation to determine the components of organic C that were degraded over the course of the study. A CHO index based on molecular composition data was utilized to codify SOM components according to their observed degradation potential. Carbohydrate- and lignin-like compounds in the water-soluble fraction (WSF) demonstrated a high degradation potential, while structures with similar stoichiometries in the base-soluble fraction (BSF) were not readily degraded. The WSF of SOM also shifted to a wider range of measured molecular masses including an increased prevalence of larger compounds, while the size distribution of compounds in the BSF changed little over the same period. Additionally, the molecular profiling data indicated an apparently ordered incorporation of organic nitrogen in the BSF immobilized as primary and secondary amines, possibly as components of N-heterocycles, which may provide insight into nitrogen immobilization or mobilization processes in SOM. Our study represents an important step forward for studying Arctic SOM with improved understanding of the molecular properties of soil organic C and the ability to represent SOM in climate models that will predict the impact of climate change on soil C and nutrient cycling.

  10. The functional potential of high Arctic permafrost revealed by metagenomic sequencing, qPCR and microarray analyses.

    Science.gov (United States)

    Yergeau, Etienne; Hogues, Hervé; Whyte, Lyle G; Greer, Charles W

    2010-09-01

    The fate of the carbon stocked in permafrost following global warming and permafrost thaw is of major concern in view of the potential for increased CH(4) and CO(2) emissions from these soils. Complex carbon compound degradation and greenhouse gas emissions are due to soil microbial communities, but no comprehensive study has yet addressed their composition and functional potential in permafrost. Here, a 2-m deep permafrost sample and its overlying active layer soil were subjected to metagenomic sequencing, quantitative PCR (qPCR) and microarray analyses. The active layer soil and the 2-m permafrost microbial community structures were very similar, with Actinobacteria being the dominant phylum. The two samples also possessed a highly similar spectrum of functional genes, especially when compared with other already published metagenomes. Key genes related to methane generation, methane oxidation and organic matter degradation were highly diverse for both samples in the metagenomic libraries and some (for example, pmoA) showed relatively high abundance in qPCR assays. Genes related to nitrogen fixation and ammonia oxidation, which could have important roles following climatic change in these nitrogen-limited environments, showed low diversity but high abundance. The 2-m permafrost showed lower abundance and diversity for all the assessed genes and taxa. Experimental biases were also evaluated using qPCR and showed that the whole-community genome amplification technique used caused representational biases in the metagenomic libraries by increasing the abundance of Bacteroidetes and decreasing the abundance of Actinobacteria. This study describes for the first time the detailed functional potential of permafrost-affected soils.

  11. 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

  12. Variability in Canopy Transpiration with Atmospheric Drivers and Permafrost Thaw Depth in an Arctic Siberian Larch Forest

    Science.gov (United States)

    Loranty, M. M.; Berner, L. T.; Alexander, H. D.; Davydov, S. P.

    2014-12-01

    Arctic ecosystems are experiencing rapid change associated with amplified rates of climate warming. A general increase in vegetation productivity has been among the expected responses for terrestrial ecosystems in the Arctic. However, recent evidence from satellite derived productivity metrics has revealed a high degree of spatial heterogeneity in the magnitude, and even the direction, of productivity trends in recent decades. Declines in productivity may seem counterintuitive in what are traditionally thought to be temperature limited ecosystems. However a warmer and drier atmosphere in conjunction with changing permafrost conditions may impose hydrologic stresses on vegetation as well. Many Siberian ecosystems receive annual precipitation inputs characteristics of arid and semiarid regions. Boreal forests persist because permafrost acts as an aquatard trapping water near the surface and because historically cool growing season temperatures have kept atmospheric evaporative demand relatively low. As climate change simultaneously warms the atmosphere and deepens the active layer it is likely that vegetation will experience a higher degree of hydrologic limitation, perhaps necessitating the reallocation of resources. Here we use sap flux observations of canopy transpiration to understand the influence of atmospheric and permafrost conditions on the function of an arctic boreal forest in northeastern Siberia. We find that individual trees exhibit stronger responses to atmospheric vapor pressure deficit (D) as the growing season progresses. Further, the magnitude of this response appears to be positively correlated with changes in the depth of permafrost thaw. These results imply that arctic boreal forests will need to adapt to increasing hydrologic stress in order to benefit from what are typically thought of as increasingly favorable growing conditions with continued climate change.

  13. Potential carbon emissions dominated by carbon dioxide from thawed permafrost soils

    Science.gov (United States)

    Schädel, Christina; Bader, Martin K.-F.; Schuur, Edward A. G.; Biasi, Christina; Bracho, Rosvel; Čapek, Petr; de Baets, Sarah; Diáková, Kateřina; Ernakovich, Jessica; Estop-Aragones, Cristian; Graham, David E.; Hartley, Iain P.; Iversen, Colleen M.; Kane, Evan; Knoblauch, Christian; Lupascu, Massimo; Martikainen, Pertti J.; Natali, Susan M.; Norby, Richard J.; O'Donnell, Jonathan A.; Chowdhury, Taniya Roy; Šantrůčková, Hana; Shaver, Gaius; Sloan, Victoria L.; Treat, Claire C.; Turetsky, Merritt R.; Waldrop, Mark P.; Wickland, Kimberly P.

    2016-10-01

    Increasing temperatures in northern high latitudes are causing permafrost to thaw, making large amounts of previously frozen organic matter vulnerable to microbial decomposition. Permafrost thaw also creates a fragmented landscape of drier and wetter soil conditions that determine the amount and form (carbon dioxide (CO2), or methane (CH4)) of carbon (C) released to the atmosphere. The rate and form of C release control the magnitude of the permafrost C feedback, so their relative contribution with a warming climate remains unclear. We quantified the effect of increasing temperature and changes from aerobic to anaerobic soil conditions using 25 soil incubation studies from the permafrost zone. Here we show, using two separate meta-analyses, that a 10 °C increase in incubation temperature increased C release by a factor of 2.0 (95% confidence interval (CI), 1.8 to 2.2). Under aerobic incubation conditions, soils released 3.4 (95% CI, 2.2 to 5.2) times more C than under anaerobic conditions. Even when accounting for the higher heat trapping capacity of CH4, soils released 2.3 (95% CI, 1.5 to 3.4) times more C under aerobic conditions. These results imply that permafrost ecosystems thawing under aerobic conditions and releasing CO2 will strengthen the permafrost C feedback more than waterlogged systems releasing CO2 and CH4 for a given amount of C.

  14. Comparison of algorithms and parameterisations for infiltration into organic-covered permafrost soils

    Science.gov (United States)

    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 v...

  15. Selective preservation of old organic carbon fluvially released from sub-Arctic soils

    Science.gov (United States)

    Vonk, Jorien E.; van Dongen, Bart E.; Gustafsson, Örjan

    2010-06-01

    Amplified climate warming in the Arctic may cause thaw-remobilization of its large soil organic carbon (SOC) pool. Here we assess the remobilization and preservation of old SOC by the watershed-integrated radiocarbon signature of molecular SOC markers released from northernmost Scandinavia. The radiocarbon analyses revealed a remarkable fractionation for identical vascular plant markers (˜420‰ or ˜6000 14C years) upon settling from surface water to the underlying sediments. From this, we infer fluvial export of two SOC pools; a young surface peat component, and an old deep mineral soil component. The young pool exists as an easily degradable humic suspension, while the old pool is matrix protected from degradation and ballasted for preferential settling. The two soil types with highest OC in Arctic permafrost evidently exhibit different susceptibilities to degradation. Hence, a significant part of the thaw-released OC may simply be fluvially relocated to sediments instead of being emitted to the atmosphere.

  16. Temperature regimes of northern taiga soils in the isolated permafrost zone of Western Siberia

    Science.gov (United States)

    Goncharova, O. Yu.; Matyshak, G. V.; Bobrik, A. A.; Moskalenko, N. G.; Ponomareva, O. E.

    2015-12-01

    Soil temperature regimes were studied in three ecosystems of the north of Western Siberia in the zone of isolated permafrost: the forest ecosystem with gleyic loamy sandy podzol (Stagnic Albic Podzol), the flat-topped peat mound ecosystem with humus-impregnated loamy sandy to light loamy peat cryozem (Histic Oxyaquic Turbic Cryosol (Arenic)), and the peat mound (palsa) ecosystem with oligotrophic destructive permafrost-affected peat soil (Cryic Histosol). Annual temperature measurements in the soil profiles demonstrated that these soils function under different temperature regimes: very cold permafrost regime and cold nonpermafrost regime. The following annual temperature characteristics proved to be informative for the studied soils: sums of above-zero temperatures at the depths of 10 and 20 cm, the maximum depth of penetration of temperatures above 10°C, and the number of days with daily soil temperatures above (or below) 0°C at the depth of 20 cm. On the studied territory, the insulating effect of the snow cover in winter was at least two times more pronounced than the insulating effect of the vegetation cover in summer. Cryogenic soils of the studied region are characterized by the high buffering towards changing climatic parameters. This is explained by the presence of the litter and peat horizons with a very low thermal diffusivity and by the presence of permafrost at a relatively shallow depth with temperature gradients preventing penetration of heat to the permafrost table.

  17. Permafrost carbon-climate feedback is sensitive to deep soil carbon decomposability but not deep soil nitrogen dynamics.

    Science.gov (United States)

    Koven, Charles D; Lawrence, David M; Riley, William J

    2015-03-24

    Permafrost soils contain enormous amounts of organic carbon whose stability is contingent on remaining frozen. With future warming, these soils may release carbon to the atmosphere and act as a positive feedback to climate change. Significant uncertainty remains on the postthaw carbon dynamics of permafrost-affected ecosystems, in particular since most of the carbon resides at depth where decomposition dynamics may differ from surface soils, and since nitrogen mineralized by decomposition may enhance plant growth. Here we show, using a carbon-nitrogen model that includes permafrost processes forced in an unmitigated warming scenario, that the future carbon balance of the permafrost region is highly sensitive to the decomposability of deeper carbon, with the net balance ranging from 21 Pg C to 164 Pg C losses by 2300. Increased soil nitrogen mineralization reduces nutrient limitations, but the impact of deep nitrogen on the carbon budget is small due to enhanced nitrogen availability from warming surface soils and seasonal asynchrony between deeper nitrogen availability and plant nitrogen demands. Although nitrogen dynamics are highly uncertain, the future carbon balance of this region is projected to hinge more on the rate and extent of permafrost thaw and soil decomposition than on enhanced nitrogen availability for vegetation growth resulting from permafrost thaw.

  18. Distribution of glacial deposits, soils, and permafrost in Taylor Valley, Antarctica

    Science.gov (United States)

    Bockheim, James G.; Prentice, M.L.; McLeod, M.

    2008-01-01

    We provide a map of lower and central Taylor Valley, Antarctica, that shows deposits from Taylor Glacier, local alpine glaciers, and grounded ice in the Ross Embayment. From our electronic database, which includes 153 sites from the coast 50 km upvalley to Pearse Valley, we show the distribution of permafrost type and soil subgroups according to Soil Taxonomy. Soils in eastern Taylor Valley are of late Pleistocene age, cryoturbated due to the presence of ground ice or ice-cemented permafrost within 70 cm of the surface, and classified as Glacic and Typic Haploturbels. In central Taylor Valley, soils are dominantly Typic Anhyorthels of mid-Pleistocene age that have dry-frozen permafrost within the upper 70 cm. Salt-enriched soils (Salic Anhyorthels and Petrosalic Anhyorthels) are of limited extent in Taylor Valley and occur primarily on drifts of early Pleistocene and Pliocene age. Soils are less developed in Taylor Valley than in nearby Wright Valley, because of lesser salt input from atmospheric deposition and salt weathering. Ice-cemented permafrost is ubiquitous on Ross Sea, pre-Ross Sea, and Bonney drifts that occur within 28 km of the McMurdo coast. In contrast, dry-frozen permafrost is prevalent on older (???115 ky) surfaces to the west. ?? 2008 Regents of the University of Colorado.

  19. Effects of Conversion from Boreal Forest to Arctic Steppe on Soil Communities and Ecosystem Carbon Pools

    Science.gov (United States)

    Han, P. D.; Natali, S.; Schade, J. D.; Zimov, N.; Zimov, S. A.

    2014-12-01

    The end of the Pleistocene marked the extinction of a great variety of arctic megafauna, which, in part, led to the conversion of arctic grasslands to modern Siberian larch forest. This shift may have increased the vulnerability of permafrost to thawing because of changes driven by the vegetation shift; the higher albedo of grassland and low insulation of snow trampled by animals may have decreased soil temperatures and reduced ground thaw in the grassland ecosystem, resulting in protection of organic carbon in thawed soil and permafrost. To test these hypothesized impacts of arctic megafauna, we examined an experimental reintroduction of large mammals in northeast Siberia, initiated in 1988. Pleistocene Park now contains 23 horses, three musk ox, one bison, and several moose in addition to the native fauna. The park is 16 square km with a smaller enclosure (animals spend most of their time and our study was focused. We measured carbon-pools in forested sites (where scat surveys showed low animal use), and grassy sites (which showed higher use), within the park boundaries. We also measured thaw depth and documented the soil invertebrate communities in each ecosystem. There was a substantial difference in number of invertebrates per kg of organic soil between the forest (600 ± 250) and grassland (300 ± 250), though these differences were not statistically significant they suggest faster nutrient turnover in the forest or a greater proportion of decomposition by invertebrates than other decomposers. While thaw depth was deeper in the grassland (60 ± 4 cm) than in the forest (40 ± 6 cm), we did not detect differences in organic layer depth or percent organic matter between grassland and forest. However, soil in the grassland had higher bulk density, and higher carbon stocks in the organic and mineral soil layers. Although deeper thaw depth in the grassland suggests that more carbon is available to microbial decomposers, ongoing temperature monitoring will help

  20. Potential microbial contamination during sampling of permafrost soil assessed by tracers

    Science.gov (United States)

    Bang-Andreasen, Toke; Schostag, Morten; Priemé, Anders; Elberling, Bo; Jacobsen, Carsten S.

    2017-01-01

    Drilling and handling of permanently frozen soil cores without microbial contamination is of concern because contamination e.g. from the active layer above may lead to incorrect interpretation of results in experiments investigating potential and actual microbial activity in these low microbial biomass environments. Here, we present an example of how microbial contamination from active layer soil affected analysis of the potentially active microbial community in permafrost soil. We also present the development and use of two tracers: (1) fluorescent plastic microspheres and (2) Pseudomonas putida genetically tagged with Green Fluorescent Protein production to mimic potential microbial contamination of two permafrost cores. A protocol with special emphasis on avoiding microbial contamination was developed and employed to examine how far microbial contamination can penetrate into permafrost cores. The quantity of tracer elements decreased with depth into the permafrost cores, but the tracers were detected as far as 17 mm from the surface of the cores. The results emphasize that caution should be taken to avoid microbial contamination of permafrost cores and that the application of tracers represents a useful tool to assess penetration of potential microbial contamination into permafrost cores. PMID:28230151

  1. Potential microbial contamination during sampling of permafrost soil assessed by tracers

    Science.gov (United States)

    Bang-Andreasen, Toke; Schostag, Morten; Priemé, Anders; Elberling, Bo; Jacobsen, Carsten S.

    2017-02-01

    Drilling and handling of permanently frozen soil cores without microbial contamination is of concern because contamination e.g. from the active layer above may lead to incorrect interpretation of results in experiments investigating potential and actual microbial activity in these low microbial biomass environments. Here, we present an example of how microbial contamination from active layer soil affected analysis of the potentially active microbial community in permafrost soil. We also present the development and use of two tracers: (1) fluorescent plastic microspheres and (2) Pseudomonas putida genetically tagged with Green Fluorescent Protein production to mimic potential microbial contamination of two permafrost cores. A protocol with special emphasis on avoiding microbial contamination was developed and employed to examine how far microbial contamination can penetrate into permafrost cores. The quantity of tracer elements decreased with depth into the permafrost cores, but the tracers were detected as far as 17 mm from the surface of the cores. The results emphasize that caution should be taken to avoid microbial contamination of permafrost cores and that the application of tracers represents a useful tool to assess penetration of potential microbial contamination into permafrost cores.

  2. Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire

    DEFF Research Database (Denmark)

    Abbott, Benjamin W.; Jones, Jeremy B.; Schuur, Edward A. G.

    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......-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...... 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...

  3. 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.

  4. Vertical electric sounding of selected Arctic and Antarctic soils: advances in express field investigation of the Cryosols

    Science.gov (United States)

    Abakumov, Evgeny

    2016-04-01

    Physical properties of the soils of the cold environments are underestimated. Soil and permafrost border and active layer thickness are the key classification indicators for the polar soils. That is why electrophysical research has been conducted with aim to determine the soil-permafrost layer heterogeneity and the depth of the uppermost permafrost layer on examples of selected plots in Antarctic region and Russian Arctic. The electric resistivity (ER) was measured directly in the soil profiles using the vertical electrical sounding (VERS) method, which provides data on the changes in the electrical resistivity throughout the profile from the soil surface without digging pits or drilling. This method allows dividing the soil layer vertically into genetic layers, which are different on main key properties and characteristics Different soil layers have different ER values, that is why the sharp changes in ER values in soil profile can be interpreted as results of transition of one horizon to another. In our study, the resistivity measurements were performed using four-electrode (AB + MN) arrays of the AMNB configuration with use of the Schlumberger geometry. A Landmapper ERM-03 instrument (Landviser, USA) was used for the VES measurements in this study. Electrodes were situated on the soil surface, distance between M and N was fixes, while distance from A to B were changed during the sounding. Vertical Electrical Resistivity Soundings (VERS) using Schlumberger array were carried out at stations, situated on the different plots of terrestrial ecosystems of Arctic and Antarctic. The resistance readings at every VERS point were automatically displayed on the digital readout screen and then written down on the field note book. The soils had been 'sounded' thoroughly and found to vary between 5 cm and 3-5 m in A-B distances. It was shown that use of VES methodology in soil survey is quite useful for identification of the permafrost depth without digging of soil pit. This

  5. Nitrogen and phosphorus in Yedoma soils of Northeast Siberia: stocks, fluxes and the ecosystem consequences of nutrient release from permafrost thaw

    Science.gov (United States)

    Mack, M. C.; Finlay, J. C.; Demarco, J.; Chapin, F.; Schuur, E. A.; Neff, J. C.; Zimov, S. A.

    2010-12-01

    About 1,672 Pg of organic carbon (C) reside in the permafrost soils and sediments of Arctic and Boreal regions. Because this stock is more than twice the size of the atmospheric C pool, there has been considerable interest in understanding how the C balance of permafrost ecosystems will respond to observed and predicted climate warming. One factor that may strongly influence landscape carbon balance in these ecosystems is the release of nutrients from thawing permafrost. Because both terrestrial and freshwater aquatic productivity are limited by the availability of nitrogen (N) and/or phosphorus (P) in high latitude systems, release of these nutrients upon thaw could increase plant nutrient availability, stimulate primary productivity and offset emissions of permafrost C. Here we report the results of a combined field and laboratory study to determine the potential importance of nutrient release from thawing Yedoma permafrost soils, which contain about 30% of the global permafrost C pool. At field sites near Cherskiy, Russia, we assessed evidence for nutrient limitation of primary production in upland forests. We also transported permafrost soils to the lab, where we measured concentration, release upon thaw, and production of N and P over a one-year incubation. Initial CO2 respired during this incubation had a radiocarbon age between 21-25 ka BP, confirming that these soils had been frozen since the late Pleistocene. Evidence from upland plant communities suggested that N constrains plant productivity. Across multiple plant functional types, foliar N concentrations and N:P ratios were low relative to pan-arctic averages. The efficiency of N retranslocation at leaf senescence was four times higher than P retranslocation, and post-senescence litter N concentrations were substantially lower than global averages. In the laboratory incubation, Yedoma soils produced 250 ± 107 ug N g soil-1yr-1 (mean ± 1 SE) and 70 ± 4 ug P g soil-1yr-1. Of this amount, 39 ± 3% of

  6. Climate change and the permafrost carbon feedback

    Science.gov (United States)

    Schuur, E.A.G.; McGuire, Anthony; 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.

  7. Improved quantification of microbial CH4 oxidation efficiency in Arctic wetland soils using carbon isotope fractionation

    Directory of Open Access Journals (Sweden)

    E.-M. Pfeiffer

    2012-12-01

    Full Text Available Permafrost-affected tundra soils are significant sources of the climate-relevant trace gas methane (CH4. The observed accelerated warming of the Arctic will cause a deeper permafrost thawing followed by increased carbon mineralization and CH4 formation in water saturated tundra soils which might cause a positive feedback to climate change. Aerobic CH4 oxidation is regarded as the key process reducing CH4 emissions from wetlands, but quantification of turnover rates has remained difficult so far. The application of carbon stable isotope fractionation enables the in situ quantification of CH4 oxidation efficiency in arctic wetland soils. The aim of the current study is to quantify CH4 oxidation efficiency in permafrost-affected tundra soils in Russia's Lena River Delta based on stable isotope signatures of CH4. Therefore, depth profiles of CH4 concentrations and δ13CH4-signatures were measured and the fractionation factors for the processes of oxidation (αox and diffusion (αdiff were determined. Most previous studies employing stable isotope fractionation for the quantification of CH4 oxidation in soils of other habitats (e.g. landfill cover soils have assumed a gas transport dominated by advection (αtrans = 1. In tundra soils, however, diffusion is the main gas transport mechanism, aside from ebullition. Hence, diffusive stable isotope fractionation has to be considered. For the first time, the stable isotope fractionation of CH4 diffusion through water-saturated soils was determined with an αdiff = 1.001 ± 0.000 (n = 3. CH4 stable isotope fractionation during diffusion through air-filled pores of the investigated polygonal tundra soils was αdiff = 1.013 ± 0.003 (n = 18. Furthermore, it was found that αox differs widely between sites and horizons (mean αox, = 1.017 ± 0.009 and needs to be determined individually. The impact of both fractionation factors on the quantification of CH4 oxidation was analyzed by considering both the

  8. A Numerical Study of Pore Fluid and Gas Migration Patterns Within Arctic Shelf Sediments Associated With Relict Off-Shore Permafrost

    Science.gov (United States)

    Frederick, J. M.; Buffett, B. A.

    2012-12-01

    Permafrost-associated methane hydrate deposits along the shallow Arctic continental shelf are thought to be a relict of glacial periods, when a large volume of Earth's water was locked up in polar ice and sea levels were lower, exposing the continental shelves to sub-freezing temperatures. Because of the cold surface temperatures, hydrate deposits are potentially stable here at unusually shallow depths, creating an extensive near-surface carbon reservoir. However, re-submergence of the shelf due to rising sea levels since the last glacial maximum 18 kyr ago has brought a temperature change of roughly +18C to the surface sediments. The evolution of permafrost-associated methane hydrate deposits is potentially complex, and an understanding of the temperature field alone is not sufficient. Salt, which is concentrated in pore fluids when permafrost forms, substantially changes the growth and decay of both permafrost and methane hydrate. The permafrost, in particular, has a strong influence on the mobility of gas within the shelf sediments. In order to quantify these complex interactions we have developed a two-dimensional, finite-volume model for two-phase flow of pore fluid and methane gas within Arctic shelf sediments. We track the evolution of temperature, salinity, and pressure fields with prescribed boundary conditions, and account for latent heat of water ice formation during growth or decay of permafrost. The permeability structure of the sediments is coupled to changes in permafrost. The model can be run over several glacial cycles to simulate the natural environment in which Arctic hydrate deposits form, while also allowing us to explore the consequences of addition warming due to anthropogenic forcing. Preliminary results show that pore fluid and gas migration is strongly influenced by the permeability variations imposed by the overlying permafrost. When permafrost grows, high salinity pore fluids form as salt is excluded from ice. Increasing salinity

  9. Soil surface organic layers in Arctic Alaska: Spatial distribution, rates of formation, and microclimatic effects

    Science.gov (United States)

    Baughman, Carson A.; Mann, Daniel H.; Verbyla, David L.; Kunz, Michael L.

    2015-06-01

    Organic layers of living and dead vegetation cover the ground surface in many permafrost landscapes and play important roles in ecosystem processes. These soil surface organic layers (SSOLs) store large amounts of carbon and buffer the underlying permafrost and its contained carbon from changes in aboveground climate. Understanding the dynamics of SSOLs is a prerequisite for predicting how permafrost and carbon stocks will respond to warming climate. Here we ask three questions about SSOLs in a representative area of the Arctic Foothills region of northern Alaska: (1) What environmental factors control the thickness of SSOLs and the carbon they store? (2) How long do SSOLs take to develop on newly stabilized point bars? (3) How do SSOLs affect temperature in the underlying ground? Results show that SSOL thickness and distribution correlate with elevation, drainage area, vegetation productivity, and incoming solar radiation. A multiple regression model based on these correlations can simulate spatial distribution of SSOLs and estimate the organic carbon stored there. SSOLs develop within a few decades after a new, sandy, geomorphic surface stabilizes but require 500-700 years to reach steady state thickness. Mature SSOLs lower the growing season temperature and mean annual temperature of the underlying mineral soil by 8 and 3°C, respectively. We suggest that the proximate effects of warming climate on permafrost landscapes now covered by SSOLs will occur indirectly via climate's effects on the frequency, extent, and severity of disturbances like fires and landslides that disrupt the SSOLs and interfere with their protection of the underlying permafrost.

  10. Soil surface organic layers in Arctic Alaska: spatial distribution, rates of formation, and microclimatic effects

    Science.gov (United States)

    Baughman, Carson A.; Mann, Daniel H.; Verbyla, David L.; Kunz, Michael L.

    2015-01-01

    Organic layers of living and dead vegetation cover the ground surface in many permafrost landscapes and play important roles in ecosystem processes. These soil surface organic layers (SSOLs) store large amounts of carbon and buffer the underlying permafrost and its contained carbon from changes in aboveground climate. Understanding the dynamics of SSOLs is a prerequisite for predicting how permafrost and carbon stocks will respond to warming climate. Here we ask three questions about SSOLs in a representative area of the Arctic Foothills region of northern Alaska: (1) What environmental factors control the thickness of SSOLs and the carbon they store? (2) How long do SSOLs take to develop on newly stabilized point bars? (3) How do SSOLs affect temperature in the underlying ground? Results show that SSOL thickness and distribution correlate with elevation, drainage area, vegetation productivity, and incoming solar radiation. A multiple regression model based on these correlations can simulate spatial distribution of SSOLs and estimate the organic carbon stored there. SSOLs develop within a few decades after a new, sandy, geomorphic surface stabilizes but require 500–700 years to reach steady state thickness. Mature SSOLs lower the growing season temperature and mean annual temperature of the underlying mineral soil by 8 and 3°C, respectively. We suggest that the proximate effects of warming climate on permafrost landscapes now covered by SSOLs will occur indirectly via climate's effects on the frequency, extent, and severity of disturbances like fires and landslides that disrupt the SSOLs and interfere with their protection of the underlying permafrost.

  11. Comparison of algorithms and parameterisations for infiltration into organic-covered permafrost soils

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2009-09-01

    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 15–30 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 and can be directly implemented in LSMs and HMs to improve their application in organic covered permafrost soils.

  12. 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.

  13. Soil organic carbon stabilization by iron in permafrost regions of the Qinghai-Tibet Plateau

    Science.gov (United States)

    Mu, C. C.; Zhang, T. J.; Zhao, Q.; Guo, H.; Zhong, W.; Su, H.; Wu, Q. B.

    2016-10-01

    A close relationship exists between soil organic carbon (SOC) and reactive iron; however, little is known about the role of iron in SOC preservation in permafrost regions. We determined the amount of SOC associated with reactive iron phases (OC-Fe) in the permafrost regions of the Qinghai-Tibetan Plateau (QTP). The results showed that the percentage of OC-Fe ranged between 0.9% and 59.5% in the upper 30 cm of soil and that the OC-Fe represented 19.5 ± 12.3% of the total SOC pool. No clear vertical distribution pattern in OC-Fe was present in the upper 1 m of soil. Throughout the year, the OC-Fe accounted for relatively stable proportions of the total SOC pool. This study suggests that approximately 20% of SOC is a potential rusty OC pool in the permafrost regions of the QTP. Biogeochemical processes related to the reaction of iron may play important roles in soil carbon cycles in permafrost regions.

  14. Diversity Analysis of Bacterial Community from Permafrost Soil of Mo-he in China.

    Science.gov (United States)

    Dan, Dong; Zhang, Dian-Peng; Liu, Wei-Cheng; Lu, Cai-Ge; Zhang, Tao-Tao

    2014-03-01

    The permafrost soil of Mo-he in Northeast China presents a typical cold environment colonized by psychrophilic microorganisms. This study is aimed at assessing the bacterial communities of permafrost soil of Mo-he in China by sequencing the 16S rRNA genes and Mothur analysis. PCR products with universal 16S rRNA gene primers were cloned and partially sequenced, and bacterial identification at the species was performed by comparative analysis with the GenBank/EMBL/DDBJ database. A total of 266 clones were obtained with the average length of 1,050 bp. Mothur analysis showed that the coverage value of clone library was 53.78 %, Shannon diversity (H) was 4.03, Simpson diversity value was 0.018, and 74 operational taxonomic units were generated. Through phylogenetic assignment using BLASTN by more than 97 % similarity, a total of 87 tentative taxa were identified. The majority of bacterial sequences recovered in this study belonged to the Acidobacteria, Proteobacteria, Verrucomicrobia, Bacteroidetes, Chloroflexi and Chlorobi. Among them, Acidobacteria are dominant community, accounting for 30.1 % of total bacteria, followed by Proteobacteria which accounted for 22.2 %. This result reflected the acidic characteristics of the permafrost soil of which pH value was 6.0. Our study indicated that the permafrost soil of Mo-he in China has a high diversity of bacteria and represents a vast potential resource of novel bacteria. As far as we knew, this is the first report on bacterial diversity of permafrost soil of Mo-he in China.

  15. The suitability of using ASTER GDEM2 for terrain-based extraction of stream channel networks in a lowland Arctic permafrost catchment

    Directory of Open Access Journals (Sweden)

    Anna Maria Trofaier

    2015-03-01

    Full Text Available Seasonally inundated areas and water-saturated soils are common features of lowland Arctic and sub-Arctic permafrost environments. With the onset of snow melt, and water percolation down through the snowpack, a principal factor controlling stream channel flow, aside from active layer depth, is topography. This paper investigates stream channel networks derived from the advanced spaceborne thermal emission and reflection radiometer (ASTER global digital elevation model (GDEM version 2 in a static terrain-based GIS-model. The suitability of using the ASTER GDEM2 for modelling the drainage network over a low-relief terrain is assessed. The aim is to use GDEM2 for the analysis of the stream channel network and to establish the network’s connectivity to previously observed spring flood patterns over the Yamal peninsula. As such, there are two parts to this study: 1 DEM validation and 2 stream channel network analysis. The results of the DEM validation study show that the root mean square error (RMSE of the GDEM2 and reference data is approx. 10 m when compared to both reference data sets (RMSE = 12.17 m, N = 86 and RMSE = 9.64, N = 506,877, implying that the GDEM2 is sufficiently accurate for terrain-based modelling. The low connectivity between the stream channel network and seasonal inundation suggests that topographic controls play a less important role compared to the possible overbanking of lakes and basin overflow. However, drainage densities for investigated drainage basins were significantly lower than those expected from typical Arctic basins. Both more sophisticated modelling techniques as well as higher spatial resolution DEMs are needed to extract the stream channel network more accurately and hence establish a more comprehensive link between the drainage network and seasonally inundated areas.

  16. Low soil organic carbon storage in a subarctic alpine permafrost environment

    Directory of Open Access Journals (Sweden)

    M. Fuchs

    2014-07-01

    Full Text Available This study investigates the soil organic carbon (SOC storage in Tarfala Valley, Northern Sweden. Field inventories upscaled based on land cover show that this alpine permafrost environment does not store large amounts of SOC, with an estimate mean of 0.9 ± 0.2 kg C m−2 for the upper meter of soil. This is one to two orders of magnitude lower than what has been reported for lowland permafrost terrain. The SOC storage varies for different land cover classes and ranges from 0.05 kg C m−2 for stone-dominated to 8.4 kg C m−2 for grass-dominated areas. No signs of organic matter burial through cryoturbation or slope processes were found and radiocarbon dated SOC is generally of recent origin (−2. Under future climate warming an upward shift of vegetation zones may lead to a net ecosystem C uptake from increased biomass and soil development. As a consequence, alpine permafrost environments could act as a net carbon sink in the future, as there is no loss of older or deeper SOC from thawing permafrost.

  17. 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

  18. Thermokarst dynamics and soil organic matter characteristics controlling initial carbon release from permafrost soils in the Siberian Yedoma region

    Science.gov (United States)

    Weiss, Niels; Blok, Daan; Elberling, Bo; Hugelius, Gustaf; Jørgensen, Christian Juncher; Siewert, Matthias Benjamin; Kuhry, Peter

    2016-07-01

    This study relates soil organic matter (SOM) characteristics to initial soil incubation carbon release from upper permafrost samples in Yedoma region soils of northeastern Siberia, Russia. Carbon (C) and nitrogen (N) content, carbon to nitrogen ratios (C:N), δ13C and δ15N values show clear trends that correspond with SOM age and degree of decomposition. Incubation results indicate that older and more decomposed soil material shows higher C respiration rates per unit incubated C than younger and less decomposed samples with higher C content. This is important as undecomposed material is often assumed to be more reactive upon thawing. Large stocks of SOM and their potential decomposability, in combination with complex landscape dynamics that include one or more events of Holocene thaw in most of the landscape, are of consequence for potential greenhouse gas release from permafrost soils in the Yedoma region.

  19. Thermokarst dynamics and soil organic matter characteristics controlling initial carbon release from permafrost soils in the Siberian Yedoma region

    DEFF Research Database (Denmark)

    Weiss, Niels; Blok, Daan; Elberling, Bo;

    2016-01-01

    This study relates soil organic matter (SOM) characteristics to initial soil incubation carbon release from upper permafrost samples in Yedoma region soils of northeastern Siberia, Russia. Carbon (C) and nitrogen (N) content, carbon to nitrogen ratios (C:N), δ13C and δ15N values show clear trends...... that correspond with SOM age and degree of decomposition. Incubation results indicate that older and more decomposed soil material shows higher C respiration rates per unit incubated C than younger and less decomposed samples with higher C content. This is important as undecomposed material is often assumed...... to be more reactive upon thawing. Large stocks of SOM and their potential decomposability, in combination with complex landscape dynamics that include one or more events of Holocene thaw in most of the landscape, are of consequence for potential greenhouse gas release from permafrost soils in the Yedoma...

  20. Environmental factors influencing trace house gas production in permafrost-affected soils

    Science.gov (United States)

    Walz, Josefine; Knoblauch, Christian; Böhme, Luisa; Pfeiffer, Eva-Maria

    2016-04-01

    The permafrost-carbon feedback has been identified as a major feedback mechanism to climate change. Soil organic matter (SOM) decomposition in the active layer and thawing permafrost is an important source of atmospheric carbon dioxide (CO2) and methane (CH4). Decomposability and potential CO2 and CH4 production are connected to the quality of SOM. SOM quality varies with vegetation composition, soil type, and soil depth. The regulating factors affecting SOM decomposition in permafrost landscapes are not well understood. Here, we incubated permafrost-affected soils from a polygonal tundra landscape in the Lena Delta, Northeast Siberia, to examine the influence of soil depth, oxygen availability, incubation temperature, and fresh organic matter addition on trace gas production. CO2 production was always highest in topsoil (0 - 10 cm). Subsoil (10 - 50 cm) and permafrost (50 - 90 cm) carbon did not differ significantly in their decomposability. Under anaerobic conditions, less SOM was decomposed than under aerobic conditions. However, in the absence of oxygen, CH4 can also be formed, which has a substantially higher warming potential than CO2. But, within the four-month incubation period (approximate period of thaw), methanogenesis played only a minor role with CH4 contributing 1-30% to the total anaerobic carbon release. Temperature and fresh organic matter addition had a positive effect on SOM decomposition. Across a temperature gradient (1, 4, 8°C) aerobic decomposition in topsoil was less sensitive to temperature than in subsoil or permafrost. The addition of labile plant organic matter (13C-labelled Carex aquatilis, a dominant species in the region) significantly increased overall CO2 production across different depths and temperatures. Partitioning the total amount of CO2 in samples amended with Carex material into SOM-derived CO2 and Carex-derived CO2, however, revealed that most of the additional CO2 could be assigned to the organic carbon from the amendment

  1. 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; William B. Bowden,; M. Syndonia Bret-Harte,; Howard E. Epstein,; Michael D. Flannigan,; Tamara K. Harms,; Teresa N. Hollingsworth,; Michelle Mack,; McGuire, Anthony; Susan M. Natali,; Adrian V. Rocha,; Suzanne E. Tank,; 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.

  2. 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.

  3. Numerical investigations of the fluid flows at deep oceanic and arctic permafrost-associated gas hydrate deposits

    Science.gov (United States)

    Frederick, Jennifer Mary

    older than the host sediment. Old pore fluid age may reflect complex flow patterns, such a fluid focusing, which can cause significant lateral migration as well as regions where downward flow reverses direction and returns toward the seafloor. Longer pathlines can produce pore fluid ages much older than that expected with a one-dimensional compaction model. For steady-state models with geometry representative of Blake Ridge (USA), a well-studied hydrate province, pore fluid ages beneath regions of topography and within fractured zones can be up to 70 Ma old. Results suggest that the measurements of 129-I/127-I reflect a mixture of new and old pore fluid. However, old pore fluid need not originate at great depths. Methane within pore fluids can travel laterally several kilometers, implying an extensive source region around the deposit. Iodine age measurements support the existence of fluid focusing beneath regions of seafloor topography at Blake Ridge, and suggest that the methane source at Blake Ridge is likely shallow. The response of methane hydrate reservoirs to warming is poorly understood. The great depths may protect deep oceanic hydrates from climate change for the time being because transfer of heat by conduction is slow, but warming will eventually be felt albeit in the far future. On the other hand, unique permafrost-associated methane hydrate deposits exist at shallow depths within the sediments of the circum-Arctic continental shelves. Arctic hydrates are thought to be a relict of cold glacial periods, aggrading when sea levels are much lower and shelf sediments are exposed to freezing air temperatures. During interglacial periods, rising sea levels flood the shelf, bringing dramatic warming to the permafrost- and hydrate-bearing sediments. Permafrost-associated methane hydrate deposits have been responding to warming since the last glacial maximum ~18 kaBP as a consequence of these natural glacial cycles. This `experiment,' set into motion by nature itself

  4. Denitrifying and diazotrophic community responses to artificial warming in permafrost and tallgrass prairie soils.

    Science.gov (United States)

    Penton, Christopher R; St Louis, Derek; Pham, Amanda; Cole, James R; Wu, Liyou; Luo, Yiqi; Schuur, E A G; Zhou, Jizhong; Tiedje, James M

    2015-01-01

    Increasing temperatures have been shown to impact soil biogeochemical processes, although the corresponding changes to the underlying microbial functional communities are not well understood. Alterations in the nitrogen (N) cycling functional component are particularly important as N availability can affect microbial decomposition rates of soil organic matter and influence plant productivity. To assess changes in the microbial component responsible for these changes, the composition of the N-fixing (nifH), and denitrifying (nirS, nirK, nosZ) soil microbial communities was assessed by targeted pyrosequencing of functional genes involved in N cycling in two major biomes where the experimental effect of climate warming is under investigation, a tallgrass prairie in Oklahoma (OK) and the active layer above permafrost in Alaska (AK). Raw reads were processed for quality, translated with frameshift correction, and a total of 313,842 amino acid sequences were clustered and linked to a nearest neighbor using reference datasets. The number of OTUs recovered ranged from 231 (NifH) to 862 (NirK). The N functional microbial communities of the prairie, which had experienced a decade of experimental warming were the most affected with changes in the richness and/or overall structure of NifH, NirS, NirK and NosZ. In contrast, the AK permafrost communities, which had experienced only 1 year of warming, showed decreased richness and a structural change only with the nirK-harboring bacterial community. A highly divergent nirK-harboring bacterial community was identified in the permafrost soils, suggesting much novelty, while other N functional communities exhibited similar relatedness to the reference databases, regardless of site. Prairie and permafrost soils also harbored highly divergent communities due mostly to differing major populations.

  5. Methane release from the East Siberian Arctic Shelf: The role of subsea permafrost and other controlling factors as inferred from decadal observational and modeling efforts

    Science.gov (United States)

    Shakhova, N. E.

    2015-12-01

    Sustained methane (CH4) release from thawing Arctic permafrost to atmosphere may be a positive, major feedback to climate warming. East Siberian Arctic Shelf (ESAS) atmospheric CH4 venting was reported as on par with flux from Arctic tundra. Unlike release when ancient carbon in thawed on-land permafrost is mobilized, ESAS CH4 release is not determined by modern methanogenesis. Pre-formed CH4 largely stems from seabed deposits. Our investigation, including observational studies using hydrological, biogeochemical, geophysical, geo-electrical, microbiological, and isotopic methods, and modeling efforts to assess current subsea permafrost state and the ESAS' contribution to the regional CH4 budget, have clarified processes driving ESAS CH4 emissions. Subsea permafrost state is a major emission determinant; rates vary by 3-5 orders of magnitude. Outer ESAS CH4 emission rates, where subsea permafrost is predicted to be degraded due to long submergence by seawater, in places are similar to near-shore rates, where deep/open taliks can form due to combined heating effects of seawater, river runoff, geothermal flux, and pre-existing thermokarst. Progressive subsea permafrost thawing and decreasing ice extent could significantly increase ESAS CH4 emissions. Subsea permafrost drilling results reveal modern recently submerged subsea permafrost degradation rates, contradicting previous hypotheses that thousands of years required to form escape paths for permafrost-preserved gas. We used a decadal observational ESAS water column and atmospheric boundary layer (ABL) data set to define the minimum source strength required to explain observed seasonally-increased ABL CH4 concentration. Modeling results agree with estimates from in-situ sonar data. In <10 m shallow water ≤72% of CH4 remains in surfacing bubbles. Dissolved CH4 fate largely depends on 3 factors: dissolved CH4 water column turnover time, water column stability against vertical mixing, and turbulent diffusion and

  6. Morphology and properties of the soils of permafrost peatlands in the southeast of the Bol'shezemel'skaya tundra

    Science.gov (United States)

    Kaverin, D. A.; Pastukhov, A. V.; Lapteva, E. M.; Biasi, C.; Marushchak, M.; Martikainen, P.

    2016-05-01

    The morphology and properties of the soils of permafrost peatlands in the southeast of the Bol'shezemel'skaya tundra are characterized. The soils developing in the areas of barren peat circles differ from oligotrophic permafrost-affected peat soils (Cryic Histosols) of vegetated peat mounds in a number of morphological and physicochemical parameters. The soils of barren circles are characterized by the wellstructured surface horizons, relatively low exchangeable acidity, and higher rates of decomposition and humification of organic matter. It is shown that the development of barren peat circles on tops of peat mounds is favored by the activation of erosional and cryogenic processes in the topsoil. The role of winter wind erosion in the destruction of the upper peat and litter horizons is demonstrated. A comparative analysis of the temperature regime of soils of vegetated peat mounds and barren peat circles is presented. The soil-geocryological complex of peat mounds is a system consisting of three major layers: seasonally thawing layer-upper permafrost-underlying permafrost. The upper permafrost horizons of peat mounds at the depth of 50-90 cm are morphologically similar to the underlying permafrost. However, these layers differ in their physicochemical properties, especially in the composition and properties of their organic matter.

  7. 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

  8. Effect of soil property uncertainties on permafrost thaw projections: a calibration-constrained analysis

    Science.gov (United States)

    Harp, D. R.; Atchley, A. L.; Painter, S. L.; Coon, E. T.; Wilson, C. J.; Romanovsky, V. E.; Rowland, J. C.

    2016-02-01

    The effects of soil property uncertainties on permafrost thaw projections are studied using a three-phase subsurface thermal hydrology model and calibration-constrained uncertainty analysis. The null-space Monte Carlo method is used to identify soil hydrothermal parameter combinations that are consistent with borehole temperature measurements at the study site, the Barrow Environmental Observatory. Each parameter combination is then used in a forward projection of permafrost conditions for the 21st century (from calendar year 2006 to 2100) using atmospheric forcings from the Community Earth System Model (CESM) in the Representative Concentration Pathway (RCP) 8.5 greenhouse gas concentration trajectory. A 100-year projection allows for the evaluation of predictive uncertainty (due to soil property (parametric) uncertainty) and the inter-annual climate variability due to year to year differences in CESM climate forcings. After calibrating to measured borehole temperature data at this well-characterized site, soil property uncertainties are still significant and result in significant predictive uncertainties in projected active layer thickness and annual thaw depth-duration even with a specified future climate. Inter-annual climate variability in projected soil moisture content and Stefan number are small. A volume- and time-integrated Stefan number decreases significantly, indicating a shift in subsurface energy utilization in the future climate (latent heat of phase change becomes more important than heat conduction). Out of 10 soil parameters, ALT, annual thaw depth-duration, and Stefan number are highly dependent on mineral soil porosity, while annual mean liquid saturation of the active layer is highly dependent on the mineral soil residual saturation and moderately dependent on peat residual saturation. By comparing the ensemble statistics to the spread of projected permafrost metrics using different climate models, we quantify the relative magnitude of soil

  9. Soil Physical and Environmental Conditions Controlling Patterned-Ground Variability at a Continuous Permafrost Site, Svalbard

    DEFF Research Database (Denmark)

    Watanabe, Tatsuya; Matsuoka, Norikazu; Christiansen, Hanne Hvidtfeldt

    2017-01-01

    This study examines soil physical and environmental conditions controlling patterned-ground variability on an alluvial fan in a continuous permafrost landscape, at Adventdalen, Svalbard. On-site monitoring of ground temperature, soil moisture and snow depth, laboratory analyses of soil physical...... properties and principal component analysis indicate that the distribution of patterned ground depends primarily on soil texture, soil moisture and the winter ground thermal regime associated with snow cover. Mudboils and composite patterns (mudboils surrounded by small polygons) occupy well-drained areas...... composed of clay-rich aeolian sediments. Compared to mudboils, composite patterns show a sharper contrast in soil texture between barren centres and vegetated rims. Hummocks filled with organic materials develop on poorly drained lowlands associated with a shallow water table. Ice-wedge polygons...

  10. 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

  11. Changing Permafrost in the Arctic and its Global Effects in the 21st Century (PAGE21): A very large international and integrated project to measure the impact of permafrost degradation on the climate system

    Science.gov (United States)

    Lantuit, Hugues; Boike, Julia; Dahms, Melanie; Hubberten, Hans-Wolfgang

    2013-04-01

    The northern permafrost region contains approximately 50% of the estimated global below-ground organic carbon pool and more than twice as much as is contained in the current atmos-pheric carbon pool. The sheer size of this carbon pool, together with the large amplitude of predicted arctic climate change im-plies that there is a high potential for global-scale feedbacks from arctic climate change if these carbon reservoirs are desta-bilized. Nonetheless, significant gaps exist in our current state of knowledge that prevent us from producing accurate assess-ments of the vulnerability of the arctic permafrost to climate change, or of the implications of future climate change for global greenhouse gas (GHG) emissions. Specifically: • Our understanding of the physical and biogeochemical processes at play in permafrost areas is still insuffi-cient in some key aspects • Size estimates for the high latitude continental carbon and nitrogen stocks vary widely between regions and research groups. • The representation of permafrost-related processes in global climate models still tends to be rudimentary, and is one reason for the frequently poor perform-ances of climate models at high latitudes. The key objectives of PAGE21 are: • to improve our understanding of the processes affect-ing the size of the arctic permafrost carbon and nitro-gen pools through detailed field studies and monitor-ing, in order to quantify their size and their vulnerability to climate change, • to produce, assemble and assess high-quality datasets in order to develop and evaluate representations of permafrost and related processes in global models, • to improve these models accordingly, • to use these models to reduce the uncertainties in feed-backs from arctic permafrost to global change, thereby providing the means to assess the feasibility of stabili-zation scenarios, and • to ensure widespread dissemination of our results in order to provide direct input into the ongoing debate on

  12. Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

    Science.gov (United States)

    Juszak, Inge; Eugster, Werner; Heijmans, Monique M. P. D.; Schaepman-Strub, Gabriela

    2016-07-01

    Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0.15 ± 0.01, for sedges it was higher (0.17 ± 0.02). Dwarf shrub transmittance was 0.36 ± 0.07 on average, and sedge transmittance was 0.28 ± 0.08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17 cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and

  13. Response of soil heat-water processes to vegetation cover on the typical permafrost and seasonally frozen soil in the headwaters of the Yangtze and Yellow Rivers

    Institute of Scientific and Technical Information of China (English)

    HU HongChang; WANG GenXu; WANG YiBo; LIU GuangSheng; LI TaiBing; REN DongXing

    2009-01-01

    The response of soil temperature and moisture to vegetative cover in the active layer of permafrost and seasonally frozen soil were assessed and compared. Soil temperature and moisture, under a range of vegetation covers (92%, 65% and 30%) in the permafrost and vegetation covers (95%, 70%-80%, 40%-50% and 10%) in the seasonally frozen soil, were measured on a daily basis. A decline in vege-tation cover led to e decrease in the integral of freezing depth of active permafrost layer, but an in-crease in seasonally frozen soil. The maximum invasion depth and duration of the negative isotherm during the frozen period and of the positive isotherm during the non-frozen period clearly increased when vegetation cover declined. With a reduction of vegetation cover, the soil moisture in the active layer of the permafrost decreased for depths of 0.20-0.60 m, but increased for depths of 0.60-0.80 m, while for seasonally frozen soil, soil moisture of the entire profile (0.10-1.20 m) increased. Variation in vegetation cover alters soil heat-water processes, but the response to it is different between permafrost and seasonally frozen soil.

  14. Priming of soil organic matter decomposition in cryoturbated Arctic soils

    Science.gov (United States)

    Richter, A.; Wild, B.; Schnecker, J.; Rusalimova, O.

    2012-12-01

    The Arctic is subjected to particularly high rates of warming, with profound consequences for the carbon cycle: on the one hand plant productivity and C storage in plant biomass have been shown to increase strongly in many parts of the Arctic, on the other hand, increasing rates of soil organic matter (SOM) decomposition have been reported. One of the possibilities that could reconcile these observations is, that increased plant growth may lead to increased root exudation rates, which are known to stimulate microbial turnover of organic matter under certain circumstances, in a process termed "priming" of SOM. Two mechanisms have been brought forward that may be responsible for priming: first, easily assimilable material exuded by plant roots may help microbes to overcome their energy limitation and second, this input of labile carbon could lead to a nitrogen limitation of the microbial community and lead to nitrogen mining, i.e. decomposition of N-rich SOM. We here report on an incubation study with arctic soil investigating potential priming of SOM decomposition in organic topsoil horizons, cryoturbated organic matter and subsoil mineral horizons of tundra soil from the Taymyr peninsula in Siberia. We used arctic soils, that are characterized by cryoturbation (mixing of soil layers due to freezing and thawing), for this study. Turbated cryosols store more than 580 Gt C globally, a significant proportion of which is stored in the cryoturbated organic matter. We hypothesized that an increased availability of labile compounds would increase SOM decomposition rates, and that this effect would be strongest in horizons with a low natural availability of labile C, i.e. in the mineral subsoil. We amended soils with 13C labelled glucose, cellulose, amino acids or proteins, and measured the mineralization of SOM C as well as microbial community composition and potential activities of extracellular enzymes. Our results demonstrate that topsoil organic, cryoturbated and

  15. Remote sensing of freeze-thaw transitions in Arctic soils using the complex resistivity method

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuxin [Lawrence Berkeley National Laboratory (LBNL); Hubbard, Susan S [Lawrence Berkeley National Laboratory (LBNL); Ulrich, Craig [Lawrence Berkeley National Laboratory (LBNL); Wullschleger, Stan D [ORNL

    2013-01-01

    Our ability to monitor freeze - thaw transitions is critical to developing a predictive understanding of biogeochemical transitions and carbon dynamics in high latitude environments. In this study, we conducted laboratory column experiments to explore the potential of the complex resistivity method for monitoring the freeze - thaw transitions of the arctic permafrost soils. Samples for the experiment were collected from the upper active layer of Gelisol soils at the Barrow Environmental Observatory, Barrow Alaska. Freeze - thaw transitions were induced through exposing the soil column to controlled temperature environments at 4 C and -20 C. Complex resistivity and temperature measurements were collected regularly during the freeze - thaw transitions using electrodes and temperature sensors installed along the column. During the experiments, over two orders of magnitude of resistivity variations were observed when the temperature was increased or decreased between -20 C and 0 C. Smaller resistivity variations were also observed during the isothermal thawing or freezing processes that occurred near 0 C. Single frequency electrical phase response and imaginary conductivity at 1 Hz were found to be exclusively related to the unfrozen water in the soil matrix, suggesting that these geophysical 24 attributes can be used as a proxy for the monitoring of the onset and progression of the freeze - thaw transitions. Spectral electrical responses and fitted Cole Cole parameters contained additional information about the freeze - thaw transition affected by the soil grain size distribution. Specifically, a shift of the observed spectral response to lower frequency was observed during isothermal thawing process, which we interpret to be due to sequential thawing, first from fine then to coarse particles within the soil matrix. Our study demonstrates the potential of the complex resistivity method for remote monitoring of freeze - thaw transitions in arctic soils. Although

  16. Hydrological and Biogeochemical Trajectories Change in Response to Permafrost Thaw in Arctic and Subarctic Regions

    Science.gov (United States)

    Striegl, R. G.; Walvoord, M. A.

    2012-12-01

    High latitude regions are particularly susceptible to changes in hydrology, carbon and nutrient biogeochemistry, and ecosystem dynamics in response to climate warming. However, these regions are vast, have few historical data, and are difficult to study because of their remoteness. Large-scale studies of water and materials exports by river systems inform on changes that are occurring on the basin scale, but provide limited process level information. Conversely, process studies in small watersheds and catchments provide bounds on responses to environmental change, but have limited value in scaling to larger systems, unless the variability of controlling conditions has been adequately captured and the distribution of these conditions is known. Regional process-based models that accurately account for spatial and temporal variability can inform on the potential location and intensity of change in a basin or region. We use the Yukon River basin of Alaska USA and NW Canada as a model for understanding the trajectories of hydrologic and carbon cycle changes in permafrost-dominated landscapes. Early measurements of carbon exports by the Yukon River suggested that recent changes in hydrology were affecting C exports; this was confirmed by historical analyses of change in groundwater contributions to river flow. Since all carbon cycling processes are directly linked to water distribution, availability, and movement, we recognized the need for implementing hydrologic models to quantify the role of permafrost on water flow and distribution and to accurately project hydrologic conditions, based on historical hydrologic information, current and projected land surface and subsurface information, and current and projected climatic information. Coupling of hydrologic projections with source, sink, and other process understanding of carbon biogeochemistry resulted in improved basin scale understanding of current and future carbon dynamics in permafrost-dominated landscapes.

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

    OpenAIRE

    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 ...

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

    OpenAIRE

    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 ...

  19. Permafrost and the International Polar Year

    Science.gov (United States)

    Brown, J.; Boelhouwers, J.; Rachold, V.; Christiansen, H. H.

    2005-12-01

    Three permafrost projects are in the planning stages for 2007-2008 IPY. (1) The Permafrost Observatory Project: A Contribution to the Thermal State of Permafrost (TSP) will obtain a "snapshot" of permafrost temperatures in existing and new boreholes throughout both hemispheres. The project is a field campaign of the existing Global Terrestrial Network on Permafrost (GTN-P) that also includes the Circumpolar Active Layer Monitoring (CALM) project. (2) The Antarctic and sub-Antarctic Permafrost, Periglacial and Soil Environments project (ANTPAS) is aimed at integrating existing and new data on the distribution, thickness, age, history and physical and geochemical properties of permafrost, soils and the active-layer on the Antarctic continent and sub-Antarctic islands. A monitoring network, a regional subset of GTN-P and consisting of borehole temperatures, active-layer thickness, and periglacial and soil observations, will be established along selected environmental gradients. (3) The Arctic Circum-Polar Coastal Observatory Network (ACCO-Net) proposes to investigate approximately 20 key coastal sites including deltas and estuaries of major Siberian and North American rivers at which physical, ecological, biochemical and socio-economic changes will be observed. Both educational outreach and data management activities are key elements in the three projects and will contribute to the overall IPY goals and its legacy. Our Permafrost Legacy is to create the basis for a new generation of researcher and the "snapshot" of existing conditions as a baseline for future change assessment. The Joint Committee of the IPY has approved the three projects that include approximately 150 individuals from the 25- member International Permafrost Association (IPA). The IPA is coordinating these projects in cooperation with the International Union of Geological Sciences (IUGS), the Scientific Committee for Antarctic Research (SCAR), the Land-Ocean Interactions in the Coastal Zone (LOICZ

  20. Bioremediation treatment of hydrocarbon-contaminated Arctic soils: influencing parameters.

    Science.gov (United States)

    Naseri, Masoud; Barabadi, Abbas; Barabady, Javad

    2014-10-01

    The Arctic environment is very vulnerable and sensitive to hydrocarbon pollutants. Soil bioremediation is attracting interest as a promising and cost-effective clean-up and soil decontamination technology in the Arctic regions. However, remoteness, lack of appropriate infrastructure, the harsh climatic conditions in the Arctic and some physical and chemical properties of Arctic soils may reduce the performance and limit the application of this technology. Therefore, understanding the weaknesses and bottlenecks in the treatment plans, identifying their associated hazards, and providing precautionary measures are essential to improve the overall efficiency and performance of a bioremediation strategy. The aim of this paper is to review the bioremediation techniques and strategies using microorganisms for treatment of hydrocarbon-contaminated Arctic soils. It takes account of Arctic operational conditions and discusses the factors influencing the performance of a bioremediation treatment plan. Preliminary hazard analysis is used as a technique to identify and assess the hazards that threaten the reliability and maintainability of a bioremediation treatment technology. Some key parameters with regard to the feasibility of the suggested preventive/corrective measures are described as well.

  1. The VULCAN Project: Toward a better understanding of the vulnerability of soil organic matter to climate change in permafrost ecosystems

    Science.gov (United States)

    Plaza, C.; Schuur, E.; Maestre, F. T.

    2015-12-01

    Despite much recent research, high uncertainty persists concerning the extent to which global warming influences the rate of permafrost soil organic matter loss and how this affects the functioning of permafrost ecosystems and the net transfer of C to the atmosphere. This uncertainty continues, at least in part, because the processes that protect soil organic matter from decomposition and stabilize fresh plant-derived organic materials entering the soil are largely unknown. The objective of the VULCAN (VULnerability of soil organic CArboN to climate change in permafrost and dryland ecosystems) project is to gain a deeper insight into these processes, especially at the molecular level, and to explore potential implications in terms of permafrost ecosystem functioning and feedback to climate change. We will capitalize on a globally unique ecosystem warming experiment in Alaska, the C in Permafrost Experimental Heating Research (CiPEHR) project, which is monitoring soil temperature and moisture, thaw depth, water table depth, plant productivity, phenology, and nutrient status, and soil CO2 and CH4 fluxes. Soil samples have been collected from the CiPEHR experiment from strategic depths, depending on thaw depth, and allow us to examine effects related to freeze/thaw, waterlogging, and organic matter relocation along the soil profile. We will use physical fractionation methods to separate soil organic matter pools characterized by different preservation mechanisms of aggregation and mineral interaction. We will determine organic C and total N content, transformation rates, turnovers, ages, and structural composition of soil organic matter fractions by elemental analysis, stable and radioactive isotope techniques, and nuclear magnetic resonance tools. Acknowledgements: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 654132. Web site: http://vulcan.comule.com

  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. Soil data from fire and permafrost-thaw chronosequences in upland Picea mariana stands near Hess Creek and Tok, interior Alaska

    Science.gov (United States)

    O'Donnell, Jonathan A.; Harden, Jennifer W.; Manies, Kristen L.; Jorgenson, M. Torre; Kanevskiy, Mikhail; Xu, Xiaomei

    2013-01-01

    Soils of the Northern Circumpolar Permafrost region harbor 1,672 petagrams (Pg) (1 Pg = 1,000,000,000 kilograms) of organic carbon (OC), nearly 50 percent of the global belowground OC pool (Tarnocai and others, 2009). Of that soil OC, nearly 88 percent is presently stored in perennially frozen ground. Recent climate warming at northern latitudes has resulted in warming and thawing of permafrost in many regions (Osterkamp, 2007), which might mobilize OC stocks from associated soil reservoirs via decomposition, leaching, or erosion. Warming also has increased the magnitude and severity of wildfires in the boreal region (Turetsky and others, 2011), which might exacerbate rates of permafrost degradation relative to warming alone. Given the size and vulnerability of the soil OC pool in permafrost soils, permafrost thaw will likely function as a strong positive feedback to the climate system (Koven and others, 2011; Schaefer and others, 2011). In this report, we report soil OC inventories from two upland fire chronosequences located near Hess Creek and Tok in Interior Alaska. We sampled organic and mineral soils in the top 2 meters (m) across a range of stand ages to evaluate the effects of wildfire and permafrost thaw on soil C dynamics. These data were used to parameterize a simple process-based fire-permafrost-carbon model, which is described in detail by O’Donnell and others (2011a, b). Model simulations examine long-term changes in soil OC storage in response to fire, permafrost thaw, and climate change. These data also have been used in other papers, including Harden and others (2012), which examines C recovery post-fire, and Johnson and others (2011), which synthesizes data within the Alaska Soil Carbon Database. Findings from these studies highlight the importance of climate and disturbance (wildfire, permafrost thaw) on soil C storage, and loss of soil C from high-latitude ecosystems.

  4. Due Permafrost: a Circumpolar Remote Sensing Service for Permafrost - Evaluation and Application Case Studies

    Science.gov (United States)

    Heim, B.; Bartsch, A.; Elger, K. K.; Rinke, A.; Gellhorn, C.; Matthes, H.; Buchhorn, M.; Klehmet, K.; Soliman, A. S.; Duguay, C.; Hachem, S.; Schwamborn, G.; Muster, S.; Langer, M.; Boike, J.; Lantuit, H.; Herzschuh, U.; Seifert, F.

    2012-12-01

    The task of the ESA Data User Element DUE Permafrost project is to build up a Remote Sensing Service for permafrost applications. The DUE Permafrost remote sensing products are land temperature, soil moisture, frozen/thawed surface status, terrain parameters, land cover, and surface waters. The DUE Permafrost products are freely available for download under http://www.ipf.tuwien.ac.at/permafrost/. The products are also published at the world data centre PANGAEA (doi:10.1594/PANGAEA.780111, 2012: ESA Data User Element Permafrost), Snow parameters (snow extent and snow water equivalent) can be derived from the ESA DUE project GlobSnow. A major component is the evaluation of the DUE Permafrost products to test their scientific validity for high-latitudinal permafrost landscapes. The primary programme providing ground data is the Global Terrestrial Network for Permafrost (GTN-P) initiated by the International Permafrost Association (IPA). The involvement of scientific stakeholders and the IPA, and the ongoing evaluation of the remote sensing derived products make the DUE Permafrost products accepted by the scientific community. We show evaluation case studies of DUE Permafrost remote sensing products using GTN-P in-situ data in Alaska and Siberia. The Helmholtz Climate Initiative REKLIM (Regionale Klimaänderungen/Regional climate change) is a climate research program where regional observations and process studies are innovatively coupled with model simulations (http://www.reklim.de/en/home/). Within the REKLIM framework we spatio-temporally compare the geophysical surface parameters derived from regional climate modelling with the DUE Permafrost and DUE GlobSnow remote sensing products. The case studies are: i) spatio-temporal comparison of the ESA GlobSnow satellite-derived snow-water equivalent data with the output from the regional climate model COSMO-CLM for Central Siberia for 1987-2010. ii) circum-arctic spatio-temporal comparison of the ESA DUE Permafrost

  5. The soil carbon/nitrogen ratio and moisture affect microbial community structures in alkaline permafrost-affected soils with different vegetation types on the Tibetan plateau.

    Science.gov (United States)

    Zhang, Xinfang; Xu, Shijian; Li, Changming; Zhao, Lin; Feng, Huyuan; Yue, Guangyang; Ren, Zhengwei; Cheng, Guogdong

    2014-01-01

    In the Tibetan permafrost region, vegetation types and soil properties have been affected by permafrost degradation, but little is known about the corresponding patterns of their soil microbial communities. Thus, we analyzed the effects of vegetation types and their covariant soil properties on bacterial and fungal community structure and membership and bacterial community-level physiological patterns. Pyrosequencing and Biolog EcoPlates were used to analyze 19 permafrost-affected soil samples from four principal vegetation types: swamp meadow (SM), meadow (M), steppe (S) and desert steppe (DS). Proteobacteria, Acidobacteria, Bacteroidetes and Actinobacteria dominated bacterial communities and the main fungal phyla were Ascomycota, Basidiomycota and Mucoromycotina. The ratios of Proteobacteria/Acidobacteria decreased in the order: SM>M>S>DS, whereas the Ascomycota/Basidiomycota ratios increased. The distributions of carbon and nitrogen cycling bacterial genera detected were related to soil properties. The bacterial communities in SM/M soils degraded amines/amino acids very rapidly, while polymers were degraded rapidly by S/DS communities. UniFrac analysis of bacterial communities detected differences among vegetation types. The fungal UniFrac community patterns of SM differed from the others. Redundancy analysis showed that the carbon/nitrogen ratio had the main effect on bacteria community structures and their diversity in alkaline soil, whereas soil moisture was mainly responsible for structuring fungal communities. Thus, microbial communities and their functioning are probably affected by soil environmental change in response to permafrost degradation.

  6. Methane release from the East-Siberian Arctic Shelf and its connection with permafrost and hydrate destabilization: First results and potential future developments

    Science.gov (United States)

    Shakhova, N.; Semiletov, I.

    2012-04-01

    The East Siberian Arctic Shelf (ESAS) is home to the world's largest hydrocarbon stocks, which consist of natural gas, coal bed methane (CH4), and shallow Arctic hydrates. Until recently, the ESAS was not considered a CH4 source due to the supposed impermeability of sub-sea permafrost, which was thought to completely isolate the CH4 beneath from modern biogeochemical cycles. However, the ESAS represents an enormous potential CH4 source that could be responsive to ongoing global warming. Such response could occur in substantially shorter time than that of terrestrial Arctic ecosystems, because sub-sea permafrost has experienced long-lasting destabilization initiated by its inundation during the Holocene ocean transgression. ESAS permafrost stability and integrity is key to whether sequestered ancient carbon escapes as the potent greenhouse gas CH4. Recent data suggest the sub-sea permafrost is currently experiencing significant changes in its thermal regime. For example, our recent data obtained in the ESAS during the drilling expedition of 2011 showed no frozen sediments at all within the 53 m long drilling core at water temperatures varying from -0.6°C to -1.3°C. Unfrozen sediments provide multiple potential CH4 migration pathways. We suggest that open taliks have formed beneath the areas underlain or influenced by the nearby occurrence of fault zones, under paleo-valleys, and beneath thaw lakes submerged several thousand years ago during the ocean transgression. Temporary gas migration pathways might occur subsequent to seismic and tectonic activity in an area, due to sediment settlement and subsidence; hydrates could destabilize due to development of thermokarst-related features or ice-scouring. Recently obtained geophysical data identified numerous gas seeps, mostly above prominent reflectors, and the ubiquitous occurrence of shallow gas-charged sediments containing numerous gas chimneys, underscoring the likelihood that the ability of sub-sea permafrost to

  7. ESA Data User Element PERMAFROST: a spaceborne permafrost monitoring and information system

    Science.gov (United States)

    Bartsch, A.; Heim, B.; Boike, J.; Elger, K.; Muster, S.; Langer, M.; Westermann, S.; Sobiech, J.

    2010-12-01

    Permafrost is a subsurface phenomenon whose ground thermal regime is mainly influenced by air temperature, land cover, soil and rock properties and snow parameters. Many spaceborne applications are potentially indicative for the thermal state of Permafrost, such as ‘land surface temperature’, ‘surface moisture’, ‘freeze/thaw’, ‘terrain’, ‘vegetation’ and ‘changes of surface waters’. The major task of the ESA Data User Element Permafrost project is to develop circumarctic/-boreal Earth Observation services of these parameters with extensive involvement of the permafrost research community The DUE PERMAFROST datasets will be processed in the EO-PERMAFROST Information System and provided via a WebGIS-interface. Further information is available at www.ipf.tuwien.ac.at/ permafrost. In order to set up the required validation tasks and information services, a target area approach with specified case study regions is used. Most of the foreseen DUE PERMAFROST remote sensing applications are well established and can optimally become operational. The goal of DUE PERMAFROST is to lend confidence in their scientific utility for high-latitude permafrost landscapes. Therefore, a major component is the evaluation of the DUE PERMAFROST products. Ground measurements in the high-latitude landscapes involve challenging logistics and are networked on multidisciplinary and circum-arctic level by the Permafrost community. The International Permafrost Association (IPA) has built up the Global Terrestrial Network for Permafrost (GTN-P) that is a network of the Circumpolar Active Layer Monitoring (CALM) and the Thermal State of Permafrost (TSP) projects. A major part of the DUE PERMAFROST core User group is contributing to GTN-P. Additional members of these programs and circum-arctic networks have also been involved in the consulting process and ground data providing process. Match-up data sets of ground data and remote sensing products coincident in time and

  8. Texture and geochemistry of surface horizons of Arctic soils from a non-glaciated catchment, SW Spitsbergen

    Directory of Open Access Journals (Sweden)

    Szymański Wojciech

    2016-09-01

    Full Text Available Physical and chemical properties of Arctic soils and especially the properties of surface horizons of the soils are very important because they are responsible for the rate and character of plant colonization, development of vegetation cover, and influence the rate and depth of thawing of soils and development of active layer of permafrost during summer. The main aim of the present study is to determine and explain the spatial diversity of selected physical and chemical properties of surface horizons of Arctic soils from the non-glaciated Fuglebekken catchment located in the Hornsund area (SW Spitsbergen by means of geostatistical approach. Results indicate that soil surface horizons in the Fuglebekken catchment are characterized by highly variable physical and chemical properties due to a heterogeneous parent material (marine sediments, moraine, rock debris, tundra vegetation types, and non-uniform influence of seabirds. Soils experiencing the strongest influence of seabird guano have a lower pH than other soils. Soils developed on the lateral moraine of the Hansbreen glacier have the highest pH due to the presence of carbonates in the parent material and a lack or presence of a poorly developed and discontinuous A horizon. The soil surface horizons along the coast of the Hornsund exhibit the highest content of the sand fraction and SiO2. The surface of soils occurring at the foot of the slope of Ariekammen Ridge is characterized by the highest content of silt and clay fractions as well as Al2O3, Fe2O3, and K2O. Soils in the central part of the Fuglebekken catchment are depleted in CaO, MgO, and Na2O in comparison with soils in the other sampling sites, which indicates the highest rate of leaching in this part of the catchment.

  9. Northern Alaska Landscape/Permafrost GIS Data

    Data.gov (United States)

    Arctic Landscape Conservation Cooperative — This data set represents an updated Ecological Subsection Map for Northern Alaska. This update includes permafrost mapping to include the following new layers:...

  10. Comparison of CO2 fluxes in a larch forest on permafrost and a pine forest on non-permafrost soils in Central Siberia

    Science.gov (United States)

    Zyryanov, V.; Tchebakova, N. M.; Nakai, Y.; Zyryanova, O.; Parfenova, E. I.; Matsuura, Y.; Vygodskaya, N.

    2013-12-01

    Inter-annual and seasonal variations of energy, water and carbon fluxes and associated climate variables in a middle taiga pine (Pinus sylvestris) forest on warm sandy soils and a northern taiga larch (Larix gmelini) forest on permafrost in Central Siberia were studied from eddy covariance measurements obtained during growing seasons of 1998-2000 and 2004-2008 (except 2006) respectively. Both naturally regenerated after fire forests grew in different environments and differed by their tree stand characteristics. The pure Gmelin larch stand was 105 yr old, stem density of living trees was about 5480 trees/ha, LAI was 0.6 m2/m2, biomass (dry weight) was 0.0044 kg/m2, with average diameter of the trees at breast height 7.1 cm and mean tree height 6.8 m. The pure Scots pine stand was 215 yr old, stand structure was relatively homogenous with a stem density of 468 living trees/ha, LAI was 1.5 m2/m2, biomass (dry weight) was 10.7 kg/m2, with average diameter of the trees at breast height 28 cm and mean tree height 23 m. The climatic and soil conditions of these ecosystems were very distinctive. The habitat of the larch forest was much colder and dryer than that of the pine forest: the growing season was 1 month shorter and growing-degree days 200°C less and winters were about one month longer and colder with January temperature -37°C versus -23°C; annual precipitation was 400 mm in the larch versus 650 mm in the pine forest and maximal snow pack was 40 cm vs 70 cm. The soils were Gelisols with permafrost table within the upper 1 m in the larch stand and Pergelic Cryochrept, alluvial sandy soil with no underlying permafrost. Average daily net ecosystem exchange (NEE) was significantly smaller in the larch ecosystem - (-3-6) μmol/m2s compared to that in the pine forest (-7-8) μmol/m2s, however daily maximal NEE was about the same. Seasonal NEE in the larch forest on continuous permafrost varied from -53 to -107 and in the pine forest on non-permafrost from -180 to

  11. Seasonal and spatial variation in soil chemistry and anaerobic processes in an Arctic ecosystem

    Science.gov (United States)

    Lipson, D.; Mauritz, M.; Bozzolo, F.; Raab, T. K.; Santos, M. J.; Friedman, E. F.; Rosenbaum, M.; Angenent, L.

    2009-12-01

    Drained thaw lake basins (DTLB) are the dominant landform in the Arctic coastal plain near Barrow, Alaska. Our previous work in a DTLB showed that Fe(III) and humic substances are important electron acceptors in anaerobic respiration, and play a significant role in the C cycle of these organic-rich soils. In the current study, we investigated seasonal and spatial patterns of availability of electron acceptors and labile substrate, redox conditions and microbial activity. Landscapes within DTLB contain complex, fine-scale topography arising from ice wedge polygons, which produce raised and lowered areas. One goal of our study was to determine the effects of microtopographic variation on the potential for Fe(III) reduction and other anaerobic processes. Additionally, the soil in the study site has a complex vertical structure, with an organic peat layer overlying a mineral layer, overlying permafrost. We described variations in soil chemistry across depth profiles into the permafrost. Finally, we installed an integrated electrode/potentiostat system to electrochemically monitor microbial activity in the soil. Topographically low areas differed from high areas in most of the measured variables: low areas had lower oxidation-reduction potential, higher pH and electrical conductivity. Soil pore water from low areas had higher concentrations of Fe(III), Fe(II), dissolved organic C (DOC), and aromaticity (UV absorbance at 260nm, “A260”). Low areas also had higher concentrations of dissolve CO2 and CH4 in soil pore water. Laboratory incubations of soil showed a trend toward higher potentials for Fe(III) reduction in topographically low areas. Clearly, ice wedge-induced microtopography exerts a strong control on microbial processes in this DTLB landscape, with increased anaerobic activity occurring in the wetter, depressed areas. Soil water extracted from 5-15 cm depth had higher concentrations of Fe(III), Fe(II), A260, and DOC compared to soil water sampled from 0-5cm

  12. Evaluation Case Studies and Intercomparison with Regional Climate Model Simulations based on the DUE PERMAFROST Circumpolar Remote Sensing Service for Permafrost

    Science.gov (United States)

    Heim, Birgit; Bartsch, Annett; Elger, Kirsten; Rinke, Annette; Matthes, Heidrun; Zhou, Xu; Klehmet, Katharina; Buchhorn, Marcel; Duguay, Claude

    2014-05-01

    Permafrost is a subsurface phenomenon. However, monitoring from Earth Observation (EO) platforms can provide spatio-temporal data sets on permafrost-related indicators and geophysical parameters used in modelling and monitoring. The ESA Data User Element (DUE) Permafrost project (2009-2012) developed a suite of EO satellite-derived products: Land Surface Temperature (LST), Surface Soil Moisture (SSM), Surface Frozen and Thawed State (Freeze/Thaw), Terrain, Land Cover, and Surface Water. The satellite-derived products are weekly and monthly averages of the bio- and geophysical terrestrial parameters and static circum-Arctic maps. The final DUE Permafrost products cover the years 2007 to 2011 with a circum-Arctic coverage (north of 50°N). The products were released in 2012, and updated in 2013. Further information is available at geo.tuwien.ac.at/permafrost/. The remote sensing service also supports the EU-FP7 funded project PAGE21 - Changing Permafrost in the Arctic and its Global Effects in the 21st Century (www.page21.eu). The Global Terrestrial Network for Permafrost (GTN-P), initiated by the International Permafrost Association (IPA), is the prime program concerned with monitoring of permafrost. It provides an important database for the evaluation of EO-derived products and climate and permafrost models. GTN-P ground data ranges from air-, ground-, and borehole temperature data to active layer monitoring, soil moisture measurements, and the description of landform and vegetation. The involvement of scientific stakeholders and the IPA, and the ongoing evaluation of the satellite-derived products make the DUE Permafrost products relevant to the scientific community. The Helmholtz Climate Initiative REKLIM (Regionale KlimaAnderungen/Regional Climate Change) is a climate research program where regional observations and process studies are coupled with model simulations (http://www.reklim.de/en/home/). ESA DUE Permafrost User workshops initiated the use of EO

  13. ESA Data User Element DUE PERMAFROST Circumpolar Remote Sensing Service for Permafrost - Evaluation Case Studies and Intercomparison with Regional Climate Model Simulations

    Science.gov (United States)

    Heim, Birgit; Bartsch, Annett; Elger, Kirsten; Rinke, Annette; Matthes, Heidrun; Zhou, Xu; Klehmet, Katharina; Rockel, Burkhardt; Lantuit, Hugues; Duguay, Claude

    2015-04-01

    Permafrost is a subsurface phenomenon. However, monitoring from Earth Observation (EO) platforms can provide spatio-temporal data sets on permafrost-related indicators and quantities used in modelling and monitoring. The ESA Data User Element (DUE) Permafrost project (2009-2012) developed a suite of EO satellite-derived products: Land Surface Temperature (LST), Surface Soil Moisture (SSM), Surface Frozen and Thawed State (Freeze/Thaw), Terrain, Land Cover, and Surface Water. The satellite-derived products are weekly and monthly averages of the bio- and geophysical terrestrial parameters and static circum-Arctic maps. The final DUE Permafrost products cover the years 2007 to 2011, some products up to 2013, with a circum-Arctic coverage (north of 50°N). The products were released in 2012, and updated in 2013 and 2014. Further information is available at geo.tuwien.ac.at/permafrost/. The remote sensing service also supports the EU-FP7 funded project PAGE21 - Changing Permafrost in the Arctic and its Global Effects in the 21st Century (www.page21.eu). The Global Terrestrial Network for Permafrost (GTN-P), initiated by the International Permafrost Association (IPA), is the prime program concerned with monitoring of permafrost. It provides an important database for the evaluation of EO-derived products and climate and permafrost models. GTN-P ground data ranges from air-, ground-, and borehole temperature data to active layer monitoring, soil moisture measurements, and the description of landform and vegetation. The involvement of scientific stakeholders and the IPA, and the ongoing evaluation of the satellite-derived products make the DUE Permafrost products relevant to the scientific community. The Helmholtz Climate Initiative REKLIM (Regionale KlimaAnderungen/Regional Climate Change) is a climate research program where regional observations and process studies are coupled with model simulations (http://www.reklim.de/en/home/). ESA DUE Permafrost User workshops

  14. Fate of organic matter released from permafrost to the East Siberian Arctic Shelf: burial vs lateral transport

    Science.gov (United States)

    Bröder, Lisa; Tesi, Tommaso; Dudarev, Oleg; Semiletov, Igor; Gustafsson, Örjan

    2015-04-01

    Ongoing global warming may trigger the remobilization of old terrigenous organic carbon (TerrOC) pools into the modern carbon cycle, which could then provide a potential positive feedback for global warming. A better understanding of the fate of such material, released from thawing permafrost via rivers and coastal erosion into the Arctic shelves seas, is therefore crucial for anticipating its influence on putative carbon-climate couplings. The main goal of this study is therefore to explore how sources and degradation status of TerrOC on the East Siberian Arctic Shelf (ESAS) vary both spatially and over time. To compare processes occurring during the cross-shelf transport and after burial we analyzed a suite of well-known terrestrial and marine biomarkers as well as source-diagnostic bulk carbon isotopes (δ13C, Δ14C) in sediments from the vast ESAS. Sediments were collected at increasing distances from the main river outlets (Kolyma and Lena rivers) while sediment cores encompassed over a century of accumulation. Our results show that TerrOC concentrations vary noticeably more during cross-shelf transport than during burial in sediments. The concentrations of lignin phenols and cutin acids (tracers of vascular plants) do not display clear changes down-core, whereas they decrease over one order of magnitude along the transect. From the molecular-based degradation proxies for TerrOC (CPI of HMW lipids, the HMW acids/alkanes ratio and the acid/aldehyde ratio of lignin phenols) no clear picture arises for down-core changes. With increasing distance from the coast there appears to be a trend to more degraded TerrOC. Furthermore, across the shelf bulk parameters indicate growing relative importance of marine organic matter at the expense of TerrOC. Strongly decreasing marine biomarker concentrations over time confirm the lability of this fresh marine material towards degradation. Overall, we infer that two different key processes affect the TerrOC cycling on this

  15. Fungal palaeodiversity revealed using high-throughput metabarcoding of ancient DNA from arctic permafrost.

    Science.gov (United States)

    Bellemain, Eva; Davey, Marie L; Kauserud, Håvard; Epp, Laura S; Boessenkool, Sanne; Coissac, Eric; Geml, Jozsef; Edwards, Mary; Willerslev, Eske; Gussarova, Galina; Taberlet, Pierre; Haile, James; Brochmann, Christian

    2013-04-01

    The taxonomic and ecological diversity of ancient fungal communities was assessed by combining next generation sequencing and metabarcoding of DNA preserved in permafrost. Twenty-six sediment samples dated 16 000-32 000 radiocarbon years old from two localities in Siberia were analysed for fungal ITS. We detected 75 fungal OTUs from 21 orders representing three phyla, although rarefaction analyses suggested that the full diversity was not recovered despite generating an average of 6677 ± 3811 (mean ± SD) sequences per sample and that preservation bias likely has considerable effect on the recovered DNA. Most OTUs (75.4%) represented ascomycetes. Due to insufficient sequencing depth, DNA degradation and putative preservation biases in our samples, the recovered taxa probably do not represent the complete historic fungal community, and it is difficult to determine whether the fungal communities varied geographically or experienced a composition shift within the period of 16 000-32 000 bp. However, annotation of OTUs to functional ecological groups provided a wealth of information on the historic communities. About one-third of the OTUs are presumed plant-associates (pathogens, saprotrophs and endophytes) typical of graminoid- and forb-rich habitats. We also detected putative insect pathogens, coprophiles and keratinophiles likely associated with ancient insect and herbivore faunas. The detection of putative insect pathogens, mycoparasites, aquatic fungi and endophytes broadens our previous knowledge of the diversity of fungi present in Beringian palaeoecosystems. A large group of putatively psychrophilic/psychrotolerant fungi was also detected, most likely representing a modern, metabolically active fungal community.

  16. Ice Complex permafrost of MIS5 age in the Dmitry Laptev Strait coastal region (East Siberian Arctic)

    Science.gov (United States)

    Wetterich, Sebastian; Tumskoy, Vladimir; Rudaya, Natalia; Kuznetsov, Vladislav; Maksimov, Fedor; Opel, Thomas; Meyer, Hanno; Andreev, Andrei A.; Schirrmeister, Lutz

    2016-09-01

    Ice Complex deposits (locally known as the Buchchagy Ice Complex) are exposed at both coasts of the East Siberian Dmitry Laptev Strait and preserved below the Yedoma Ice Complex that formed during MIS3 and MIS2 (Marine Isotope Stage) and lateglacial-Holocene thermokarst deposits (MIS1). Radioisotope disequilibria (230Th/U) of peaty horizons date the Buchchagy Ice Complex deposition to 126 + 16/-13 kyr and 117 + 19/-14 kyr until 98 ± 5 kyr and 89 ± 5 kyr. The deposit is characterised by poorly-sorted medium-to-coarse silts with cryogenic structures of horizontal ice bands, lens-like, and lens-like reticulated segregation ice. Two peaty horizons within the Buchchagy Ice Complex and syngenetic ice wedges (2-4 m wide, up to 10 m high) are striking. The isotopic composition (δ18O, δD) of Buchchagy ice-wedge ice indicates winter conditions colder than during the MIS3 interstadial and warmer than during MIS2 stadial, and similar atmospheric winter moisture sources as during the MIS2 stadial. Buchchagy Ice Complex pollen spectra reveal tundra-steppe vegetation and harsher summer conditions than during the MIS3 interstadial and rather similar vegetation as during the MIS2 stadial. Short-term climatic variability during MIS5 is reflected in the record. Even though the regional chronostratigraphic relationship of the Buchchagy Ice Complex to the Last Interglacial remains unclear because numerical dating is widely lacking, the present study indicates permafrost (Ice Complex) formation during MIS5 sensu lato, and its preservation afterwards. Palaeoenvironmental insights into past climate and the periglacial landscape dynamics of arctic lowlands in eastern Siberia are deduced from the record.

  17. Tumebacillus permanentifrigoris gen. nov., sp. nov., an aerobic, spore-forming bacterium isolated from Canadian high Arctic permafrost.

    Science.gov (United States)

    Steven, Blaire; Chen, Min Qun; Greer, Charles W; Whyte, Lyle G; Niederberger, Thomas D

    2008-06-01

    A Gram-positive, aerobic, rod-shaped bacterium (strain Eur1 9.5(T)) was isolated from a 9-m-deep permafrost sample from the Canadian high Arctic. Strain Eur1 9.5(T) could not be cultivated in liquid medium and grew over the temperature range 5-37 degrees C; no growth was observed at 42 degrees C and only slow growth was observed at 5 degrees C following 1 month of incubation. Eur1 9.5(T) grew over the pH range 5.5-8.9 and tolerated NaCl concentrations of 0-0.5 % (w/v). Eur1 9.5(T) grew heterotrophically on complex carbon substrates and chemolithoautotrophically on inorganic sulfur compounds, as demonstrated by growth on sodium thiosulfate and sulfite as sole electron donors. Eur1 9.5(T) contained iso-C(15 : 0) as the major cellular fatty acid and menaquinone 7 (MK-7) as the major respiratory quinone. The cell-wall peptidoglycan was of type A1gamma. The DNA G+C content was 53.1 mol%. The 16S rRNA gene sequence of strain Eur1 9.5(T) was only distantly related (

  18. Permafrost carbon: Catalyst for deglaciation

    Science.gov (United States)

    MacDougall, Andrew H.

    2016-09-01

    The sources contributing to the deglacial rise in atmospheric CO2 concentrations are unclear. Climate model simulations suggest thawing permafrost soils were the initial source, highlighting the vulnerability of modern permafrost carbon stores.

  19. 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.

  20. Interactive effects of wildfire and permafrost on microbial communities and soil processes in an Alaskan black spruce forest

    Science.gov (United States)

    Waldrop, M.P.; Harden, J.W.

    2008-01-01

    Boreal forests contain significant quantities of soil carbon that may be oxidized to CO2 given future increases in climate warming and wildfire behavior. At the ecosystem scale, decomposition and heterotrophic respiration are strongly controlled by temperature and moisture, but we questioned whether changes in microbial biomass, activity, or community structure induced by fire might also affect these processes. We particularly wanted to understand whether postfire reductions in microbial biomass could affect rates of decomposition. Additionally, we compared the short-term effects of wildfire to the long-term effects of climate warming and permafrost decline. We compared soil microbial communities between control and recently burned soils that were located in areas with and without permafrost near Delta Junction, AK. In addition to soil physical variables, we quantified changes in microbial biomass, fungal biomass, fungal community composition, and C cycling processes (phenol oxidase enzyme activity, lignin decomposition, and microbial respiration). Five years following fire, organic surface horizons had lower microbial biomass, fungal biomass, and dissolved organic carbon (DOC) concentrations compared with control soils. Reductions in soil fungi were associated with reductions in phenol oxidase activity and lignin decomposition. Effects of wildfire on microbial biomass and activity in the mineral soil were minor. Microbial community composition was affected by wildfire, but the effect was greater in nonpermafrost soils. Although the presence of permafrost increased soil moisture contents, effects on microbial biomass and activity were limited to mineral soils that showed lower fungal biomass but higher activity compared with soils without permafrost. Fungal abundance and moisture were strong predictors of phenol oxidase enzyme activity in soil. Phenol oxidase enzyme activity, in turn, was linearly related to both 13C lignin decomposition and microbial respiration

  1. Role of Siderophores in Dissimilatory Iron Reduction in Arctic Soils : Effect of Direct Amendment of Siderophores to Arctic Soil

    Science.gov (United States)

    Srinivas, A. J.; Dinsdale, E. A.; Lipson, D.

    2014-12-01

    Dissimilatory iron reduction (DIR), where ferric iron (Fe3+) is reduced to ferrous iron (Fe2+) anaerobically, is an important respiratory pathway used by soil bacteria. DIR contributes to carbon dioxide (CO2) efflux from the wet sedge tundra biome in the Arctic Coastal Plain (ACP) in Alaska, and could competitively inhibit the production of methane, a stronger greenhouse gas than CO2, from arctic soils. The occurrence of DIR as a dominant anaerobic process depends on the availability of substantial levels of Fe3+ in soils. Siderophores are metabolites made by microbes to dissolve Fe3+ from soil minerals in iron deficient systems, making Fe3+ soluble for micronutrient uptake. However, as the ACP is not iron deficient, siderophores in arctic soils may play a vital role in anaerobic respiration by dissolving Fe3+ for DIR. We studied the effects of direct siderophore addition to arctic soils through a field study conducted in Barrow, Alaska, and a laboratory incubation study conducted at San Diego State University. In the field experiment, 50μM deferroxamine mesylate (a siderophore), 50μM trisodium nitrilotriacetate (an organic chelator) or an equal volume of water was added to isolated experimental plots, replicated in clusters across the landscape. Fe2+ concentrations were measured in soil pore water samples collected periodically to measure DIR over time in each. In the laboratory experiment, frozen soil samples obtained from drained thaw lake basins in the ACP, were cut into cores and treated with the above-mentioned compounds to the same final concentrations. Along with measuring Fe2+ concentrations, CO2 output was also measured to monitor DIR over time in each core. Experimental addition of siderophores to soils in both the field and laboratory resulted in increased concentrations of soluble Fe3+ and a sustained increase in Fe2+concentrations over time, along with increased respiration rates in siderophore-amended cores. These results show increased DIR in

  2. Changes in Hydrologic Conditions and Greenhouse Gas Emissions in Circumpolar Regions due to Climate Change-Induced Permafrost Retreat

    Science.gov (United States)

    Whiticar, M. J.; Bhatti, J.; Startsev, N.

    2012-12-01

    Thawing permafrost peatlands influence northern ecosystems by changing the regional hydrology and mobilizing the vast carbon (C) reserves that results in increased greenhouse gas (GHGs) emissions to the atmosphere. With permafrost distribution controlled largely by topography and climate, our IPY study intensively monitored the local C cycling processes and GHG fluxes associated with different hydrologic and permafrost environments at 4 sites along a latitudinal climatic gradient of Boreal, Subarctic and Arctic ecoclimatic regions that extend south-north from the Isolated Patches Permafrost Zone (northern Alberta), to the Continuous Permafrost Zone (Inuvik, NWT). Each site encompasses a local hydrologic gradient from upland forest and peat plateau to collapse scar. Our multi-year measurements of peatland profiles and flux chambers for CH4 and CO2 concentrations and stable isotope ratios indicate processes, including methanogenesis, methanotrophy, transport and emission that control the distribution of these GHGs. These relationships are modulated by fluctuating local soil water and corresponding ecosystem conditions. The gas geochemistry shows that significant surface CH4 production occurs by both hydrogenotrophic and methyl-fermentative methanogenesis in submerged, anaerobic peats, e.g., collapse scars, whereas methane oxidation is restricted to aerobic, drier environments, e.g., upland sites and peat-atmosphere interface. The most active methanogenesis and emissions are in areas of actively thawing permafrost contrasting with sites under continuous permafrost. This degree of methanogenesis is being amplified by the increased rate of Arctic warming and the rapid retreat of permafrost in Canada's Arctic (ca. 2.5 km/yr).

  3. Stabilization Techniques for Road Lower Structure and Roadbed Constructed on Permafrost Soil

    Directory of Open Access Journals (Sweden)

    Vorontsov Vyacheslav

    2016-01-01

    Full Text Available The perspective development of Yamal-Nenets Autonomous District, which is rich in mineral resources is impossible without creation of the road network for communication between settlements, oil and gas fields and transport hubs. Yamal-Nenets Autonomous District is characterized by complex engineering-geological conditions where different geological and geocryological phenomena and processes are being developed causing specific approaches to design and construction of engineering structures to be used. In this regard, an urgent task is to develop constructional solutions making it possible to stabilize the road lower structure and the roadbed, prolong periods between repairs on individual sections and improve operational reliability of roads in general. The paper describes the proposed and implemented constructional and technological solutions to stabilize the road lower structure and the roadbed constructed on permafrost soils. The results of two-year geotechnical monitoring of the road sections with implemented solutions are given.

  4. Thermal regimes and degradation modes of permafrost along the Qinghai-Tibet Highway

    Institute of Scientific and Technical Information of China (English)

    JIN; Huijun; ZHAO; Lin; WANG; Shaoling

    2006-01-01

    Permafrost on the Qinghai-Tibet Plateau (QTP) is widespread, thin, and thermally unstable. Under a warming climate during the past few decades, it has been degrading extensively with generally rising ground temperatures, the deepening of the maximum summer thaw, and with lessening of the winter frost penetration. The permafrost has degraded downward, upward and laterally.Permafrost has thinned or, in some areas, has totally disappeared. The modes of permafrost degradation have great significance in geocryology, in cold regions engineering and in cold regions environmental management. Permafrost in the interior of the QTP is well represented along the Qing-hal-Tibet Highway (QTH), which crosses the Plateau through north to south and traverses 560 km of permafrost-impacted ground. Horizontally, the degradation of permafrost occurs more visibly in the sporadic permafrost zone in the vicinity of the lower limit of permafrost (LLP), along the margins of taliks, and around permafrost islands. Downward degradation develops when the maximum depth of seasonal thaw exceeds the maximum depth of seasonal frost, and it generally results in the formation of a layered talik disconnecting the permafrost from the seasonal frost layer. The downward degradation is divided into four stages: 1) initial degradation, 2) accelerated degradation, 3) layered talik and 4)finally the conversion of permafrost to seasonally frozen ground (SFG). The upward degradation occurs when the geothermal gradient in permafrost drops to less than the geothermal gradients in the underlying thawed soil layers. Three types of permafrost temperature curves (stable, degrading, and phase-changing transitory permafrost) illustrate these modes. Although strong differentiations in local conditions and permafrost types exist, the various combinations of the three degradation modes will ultimately transform permafrost into SFG. Along the QTH, the downward degradation has been proceeding at annual rates of 6 to 25 cm

  5. Annual CO2 budget and seasonal CO2 exchange signals at a high Arctic permafrost site on Spitsbergen, Svalbard archipelago

    DEFF Research Database (Denmark)

    Luërs, J.; Westermann, Signe; Piel, K.;

    2014-01-01

    The annual variability of CO2 exchange in most ecosystems is primarily driven by the activities of plants and soil microorganisms. However, little is known about the carbon balance and its controlling factors outside the growing season in Arctic regions dominated by soil freeze/thaw processes, lo...

  6. Effects of bryophyte and lichen cover on permafrost soil temperature at large scale

    Science.gov (United States)

    Porada, Philipp; Ekici, Altug; Beer, Christian

    2016-09-01

    Bryophyte and lichen cover on the forest floor at high latitudes exerts an insulating effect on the ground. In this way, the cover decreases mean annual soil temperature and can protect permafrost soil. Climate change, however, may change bryophyte and lichen cover, with effects on the permafrost state and related carbon balance. It is, therefore, crucial to predict how the bryophyte and lichen cover will react to environmental change at the global scale. To date, current global land surface models contain only empirical representations of the bryophyte and lichen cover, which makes it impractical to predict the future state and function of bryophytes and lichens. For this reason, we integrate a process-based model of bryophyte and lichen growth into the global land surface model JSBACH (Jena Scheme for Biosphere-Atmosphere Coupling in Hamburg). The model simulates bryophyte and lichen cover on upland sites. Wetlands are not included. We take into account the dynamic nature of the thermal properties of the bryophyte and lichen cover and their relation to environmental factors. Subsequently, we compare simulations with and without bryophyte and lichen cover to quantify the insulating effect of the organisms on the soil. We find an average cooling effect of the bryophyte and lichen cover of 2.7 K on temperature in the topsoil for the region north of 50° N under the current climate. Locally, a cooling of up to 5.7 K may be reached. Moreover, we show that using a simple, empirical representation of the bryophyte and lichen cover without dynamic properties only results in an average cooling of around 0.5 K. This suggests that (a) bryophytes and lichens have a significant impact on soil temperature in high-latitude ecosystems and (b) a process-based description of their thermal properties is necessary for a realistic representation of the cooling effect. The advanced land surface scheme, including a dynamic bryophyte and lichen model, will be the basis for an improved

  7. Soil moisture data for the validation of permafrost models using direct and indirect measurement approaches at three alpine sites

    Directory of Open Access Journals (Sweden)

    Cécile ePellet

    2016-01-01

    Full Text Available In regions affected by seasonal and permanently frozen conditions soil moisture influences the thermal regime of the ground as well as its ice content, which is one of the main factors controlling the sensitivity of mountain permafrost to climate changes. In this study, several well established soil moisture monitoring techniques were combined with data from geophysical measurements to assess the spatial distribution and temporal evolution of soil moisture at three high elevation sites with different ground properties and thermal regimes. The observed temporal evolution of measured soil moisture is characteristic for sites with seasonal freeze/thaw cycles and consistent with the respective site-specific properties, demonstrating the general applicability of continuous monitoring of soil moisture at high elevation areas. The obtained soil moisture data were then used for the calibration and validation of two different model approaches in permafrost research in order to characterize the lateral and vertical distribution of ice content in the ground. Calibration of the geophysically based four-phase model (4PM with spatially distributed soil moisture data yielded satisfactory two dimensional distributions of water-, ice- and air content. Similarly, soil moisture time series significantly improved the calibration of the one-dimensional heat and mass transfer model COUP, yielding physically consistent soil moisture and temperature data matching observations at different depths.

  8. Perturbation of an arctic soil microbial community by metal nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Niraj [Department of Biology, Queen' s University, Kingston, Ontario K7L 3N6 (Canada); Shah, Vishal [Department of Biology, Dowling College, Oakdale, NY 11769 (United States); Walker, Virginia K., E-mail: walkervk@queensu.ca [Department of Biology, Queen' s University, Kingston, Ontario K7L 3N6 (Canada); Department of Biology, School of Environmental Studies and Department of Microbiology and Immunology, Queen' s University, Kingston, Ontario K7L 3N6 (Canada)

    2011-06-15

    Highlights: {yields} Silver, copper and silica nanoparticles had an impact on arctic soil {yields} A microbial community toxicity indicator was developed {yields} Community surveys using pyrosequencing confirmed a shift in bacterial biodiversity {yields} Troublingly, silver nanoparticles were highly toxic to a plant beneficial bacterium - Abstract: Technological advances allowing routine nanoparticle (NP) manufacture have enabled their use in electronic equipment, foods, clothing and medical devices. Although some NPs have antibacterial activity, little is known about their environmental impact and there is no information on the influence of NPs on soil in the possibly vulnerable ecosystems of polar regions. The potential toxicity of 0.066% silver, copper or silica NPs on a high latitude (>78{sup o}N) soil was determined using community level physiological profiles (CLPP), fatty acid methyl ester (FAME) assays and DNA analysis, including sequencing and denaturing gradient gel electrophoresis (DGGE). The results of these different investigations were amalgamated in order to develop a community toxicity indicator, which revealed that of the three NPs examined, silver NPs could be classified as highly toxic to these arctic consortia. Subsequent culture-based studies confirmed that one of the community-identified plant-associating bacteria, Bradyrhizobium canariense, appeared to have a marked sensitivity to silver NPs. Thus, NP contamination of arctic soils particularly by silver NPs is a concern and procedures for mitigation and remediation of such pollution should be a priority for investigation.

  9. Exploring Viral Mediated Carbon Cycling in Thawing Permafrost Microbial Communities

    Science.gov (United States)

    Trubl, G. G.; Solonenko, N.; Moreno, M.; Sullivan, M. B.; Rich, V. I.

    2014-12-01

    Viruses are the most abundant biological entities on Earth and their impact on carbon cycling in permafrost habitats is poorly understood. Arctic C cycling is particularly important to interpret due to the rapid climate change occurring and the large amount of C stockpiled there (~1/3 of global soil C is stored in permafrost). Viruses of microbes (i.e. phages) play central roles in C cycling in the oceans, through cellular lysis (phage drive the largest ocean C flux about 150 Gt yr-1, dwarfing all others by >5-fold), production of associated DOC, as well as transport and expression during infection (1029 transduction events day-1). C cycling in thawing permafrost systems is critical in understanding the climate trajectory and phages may be as important for C cycling here as they are in the ocean. The thawed C may become a food source for microbes, producing CO2 and potentially CH4, both potent greenhouse gases. To address the potential role of phage in C cycling in these dynamic systems, we are examining phage from an arctic permafrost thaw gradient in northern Sweden. We have developed a protocol for successfully extracting phage from peat soils and are quantifying phage in 15 peat and 2 lake sediment cores, with the goal of sequencing viromes. Preliminary data suggest that phage are present at 109 g-1 across the permafrost thaw gradient (compared to the typical marine count ~105 ml-1), implying a potentially robust phage-host interaction web in these changing environments. We are examining phage from 11 depth intervals (covering the active and permafrost layer) in the cores to assess phage-host community dynamics. Phage morphology and abundance for each layer and environment are being determined using qTEM and EFM. Understanding the phage that infect bacteria and archaea in these rapidly changing habitats will provide insight into the controls on current and future CH4 and CO2 emissions in permafrost habitats.

  10. ADAPT: building conceptual models of the physical and biological processes across permafrost landscapes

    Science.gov (United States)

    Allard, M.; Vincent, W. F.; Lemay, M.

    2012-12-01

    Fundamental and applied permafrost research is called upon in Canada in support of environmental protection, economic development and for contributing to the international efforts in understanding climatic and ecological feedbacks of permafrost thawing under a warming climate. The five year "Arctic Development and Adaptation to Permafrost in Transition" program (ADAPT) funded by NSERC brings together 14 scientists from 10 Canadian universities and involves numerous collaborators from academia, territorial and provincial governments, Inuit communities and industry. The geographical coverage of the program encompasses all of the permafrost regions of Canada. Field research at a series of sites across the country is being coordinated. A common protocol for measuring ground thermal and moisture regime, characterizing terrain conditions (vegetation, topography, surface water regime and soil organic matter contents) is being applied in order to provide inputs for designing a general model to provide an understanding of transfers of energy and matter in permafrost terrain, and the implications for biological and human systems. The ADAPT mission is to produce an 'Integrated Permafrost Systems Science' framework that will be used to help generate sustainable development and adaptation strategies for the North in the context of rapid socio-economic and climate change. ADAPT has three major objectives: to examine how changing precipitation and warming temperatures affect permafrost geosystems and ecosystems, specifically by testing hypotheses concerning the influence of the snowpack, the effects of water as a conveyor of heat, sediments, and carbon in warming permafrost terrain and the processes of permafrost decay; to interact directly with Inuit communities, the public sector and the private sector for development and adaptation to changes in permafrost environments; and to train the new generation of experts and scientists in this critical domain of research in Canada

  11. The effect of permafrost on soil erosion using meteoric 10Be, 137Cs and 239+240Pu in the Eastern Swiss Alps

    Science.gov (United States)

    Pichler, Barbara; Brandovà, Dagmar; Alewell, Christine; Ivy-Ochs, Susan; Kubik, Peter W.; Kneisel, Christof; Meusburger, Katrin; Ketterer, Michael; Egli, Markus

    2013-04-01

    Permafrost ecosystems are highly sensitive to climate warming. The expected changes in the thermal and hydrological soil regime might have crucial consequences on soil erosion processes. Therefore, the determination of erosional activities on the long- (since the beginning of soil formation) and mid-term (last 50-60 yr) using cosmogenic and anthropogenic radionuclides can provide important information on past and ongoing processes. Permafrost soils in the Alps and their behaviour with climate change are only rarely studied. The expected new insights will lead to a better understanding of the processes of high mountain soils and are a further step towards improving climate-related modelling of fast warming scenarios and increasing system disequilibria. Our aim is to quantify soil erosion processes in permafrost soils and nearby unfrozen soils in the Alpine (sites at 2700 m asl) and the sub-Alpine (sites 1800 m asl) range of the Swiss Alps (Upper Engadine). We hypothesise that permafrost soils differ distinctly in their long- and mid-term soil erosion rates due to different water retention capacities. Long-term soil erosion was assessed using meteoric 10Be. Meteoric 10Be in a soil profile was estimated assuming that it is has been deposited as a function of precipitation and adsorbed in the fine earth fraction (

  12. 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......, Kangerlussuaq, Sisimiut and Nuuk. They are situated in continuous, discontinuous and sporadic permafrost zones. We will show examples of detoriation of permafrost related to present local scale climate observations and large scale climate and permafrost simulations modeled numerically with the GIPL model driven...... by HIRHAM climate projections for Greenland up to 2075. The engineering modelling is based on a risk assessment methodology based on a flow diagram which classify the risk of permafrost degradation causing settlement and stability problems for buildings and infrastructures based on relatively simple...

  13. Soil data for a thermokarst bog and the surrounding permafrost plateau forest, located at Bonanza Creek Long Term Ecological Research Site, Interior Alaska

    Science.gov (United States)

    Manies, Kristen L.; Fuller, Christopher C.; Jones, Miriam C.; Waldrop, Mark P.; McGeehin, John P.

    2017-01-19

    Peatlands play an important role in boreal ecosystems, storing a large amount of soil organic carbon. In northern ecosystems, collapse-scar bogs (also known as thermokarst bogs) often form as the result of ground subsidence following permafrost thaw. To examine how ecosystem carbon balance changes with the loss of permafrost, we measured carbon and nitrogen storage within a thermokarst bog and the surrounding forest, which continues to have permafrost. These sites are a part of the Bonanza Creek Long Term Ecological Research (LTER) site and are located within Interior Alaska. Here, we report on methods used for core collection analysis as well as the cores’ physical, chemical, and descriptive properties.

  14. The Influence of Earth Temperature on the Dynamic Characteristics of Frozen Soil and the Parameters of Ground Motion on Sites of Permafrost

    Institute of Scientific and Technical Information of China (English)

    Wang Lanmin; Zhang Dongli; Wu Zhijian; Ma Wei; Li Xiaojun

    2004-01-01

    Earth temperature is one of the most important factors influencing the mechanical properties of frozen soil. Based on the field investigation of the characteristics of ground deformation and ground failure caused by the Ms8.1 earthquake in the west of the Kuniun Mountain Pass,China, the influence of temperature on the dynamic constitutive relationship, dynamic elastic modulus, damping ratio and dynamic strength of frozen soil was quantitatively studied by means of the dynamic triaxial test. Moreover, the characteristics of ground motion on a permafrost site under different temperatures were analyzed for the four profiles of permafrost along the Qinghai-Xizang (Tibet) Railway using the time histories of ground motion acceleration with 3 exceedance probabilities of the Kunlun Mountains area. The influences of temperature on the seismic displacement, velocity, acceleration and response spectrum on permafrost ground were studied quantitatively. A scientific basis was presented for earthquake disaster mitigation for engineering foundations, highways and underground engineering in permafrost areas.

  15. BVOC fluxes in Eastern Siberian larch forest growing on permafrost soils

    Science.gov (United States)

    Holst, Thomas; Kajos, Maija K.; Hakola, Hannele; Rinne, Janne; Maximov, Ayal; Maximov, Trofim; Arneth, Almut

    2010-05-01

    Emissions of biogenic volatile organic compounds (BVOC) from the boreal forest biome contribute a large precursor source for formation and growth of secondary organic aerosol, with unknown but potentially substantial effects on atmosphere and climate. However, variation in the BVOC source distribution across the boreal forests and over the course of a growing season is poorly quantified, based on a very limited number of short-term studies in northern Europe and northern America. In eastern Siberia, Larix gmelinni forests dominate an area of ca. 28 X 106ha, one quarter of the entire Eurasian boreal forest. So far, no observations of leaf or ecosystem BVOC fluxes have been reported although it has been argued that larch is a substantial emitter of monoterpenes and sesquiterpenes. We will present first results from a number of measurement campaigns performed at the Spasskaya Pad flux station (ca. 40km to the northeast of Yakutsk, 62o15'18.4''N, 129o37'07.9''E) from a larch forest growing on permafrost soils. The forest was a substantial source of monoterpenes and of methanol with maximum rates observed during warm summer periods, when temperatures at this continental location could exceed 30oC. Leaf measurements also identified substantial sesquiterpene emissions; these compounds have a low atmospheric lifetime and could not be detected with the above-canopy flux measurements. Applying measured emission factors for the entire region suggest that the Siberian larch biome is a much larger source of monoterpenes than previously thought.

  16. Impacts of climate change on infrastructure in permafrost regions

    Science.gov (United States)

    Beloloutskaia, M.; Anisimov, O.

    2003-04-01

    There is a growing evidence of enhanced warming over the permafrost regions, and significant impacts on natural and human systems are expected. Changes in the temperature, distribution, and depth of seasonal thawing of permafrost will have direct and immediate implications for the infrastructure built upon it. The mechanical strength of permafrost decreases with warming, resulting in damage to and possible failure of buildings, pipelines, and transportation facilities. Extensive infrastructure was developed in the Arctic largely in association with the extraction and transportation industries. Several large cities in Russia with few hundred thousand population are of particular concern since many buildings there have already been affected by the changes in permafrost properties. Detrimental changes in permafrost conditions are often not abrupt. Instead, they evolve gradually and can be predicted and monitored, allowing avoidance of catastrophic events and mitigation of negative consequences. Climate-induced threats to infrastructure in permafrost regions may be evaluated using a numerical "settlement" index, Iset, which allows to classify modern permafrost with respect to its potential for thermokarst development: Iset = dZ * W, where dZ is the relative change in the depth of seasonal thawing predicted by permafrost model for the conditions of the future climate and W is the volumetric proportion of near surface soil occupied by ground ice. Permafrost model of intermediate complexity (Koudriavtcev's model) was used with selected GCM-based scenarios of climate change to construct predictive maps of "settlement" index for the mid-21st century. Circumpolar permafrost area was partitioned into zones of high, moderate, and low hazard potential. Despite discrepancies in details, all scenarios yield a zone in the high-risk category distributed discontinuously around the margins of the Arctic Ocean, indicating high potential for coastal erosion. Several population centers

  17. The microbial ecology of permafrost.

    Science.gov (United States)

    Jansson, Janet K; Taş, Neslihan

    2014-06-01

    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 features and between sites. Some microorganisms are even active at subzero temperatures in permafrost. An emerging concern is the impact of climate change and the possibility of subsequent permafrost thaw promoting microbial activity in permafrost, resulting in increased potential for greenhouse-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.

  18. Crude Oil Treatment Leads to Shift of Bacterial Communities in Soils from the Deep Active Layer and Upper Permafrost along the China-Russia Crude Oil Pipeline Route

    OpenAIRE

    Sizhong Yang; Xi Wen; Liang Zhao; Yulan Shi; Huijun Jin

    2014-01-01

    The buried China-Russia Crude Oil Pipeline (CRCOP) across the permafrost-associated cold ecosystem in northeastern China carries a risk of contamination to the deep active layers and upper permafrost in case of accidental rupture of the embedded pipeline or migration of oil spills. As many soil microbes are capable of degrading petroleum, knowledge about the intrinsic degraders and the microbial dynamics in the deep subsurface could extend our understanding of the application of in-situ biore...

  19. Site- and horizon-specific patterns of microbial community structure and enzyme activities in permafrost-affected soils of Greenland.

    Science.gov (United States)

    Gittel, Antje; Bárta, Jiří; Kohoutová, Iva; Schnecker, Jörg; Wild, Birgit; Capek, Petr; Kaiser, Christina; Torsvik, Vigdis L; Richter, Andreas; Schleper, Christa; Urich, Tim

    2014-01-01

    Permafrost-affected soils in the Northern latitudes store huge amounts of organic carbon (OC) that is prone to microbial degradation and subsequent release of greenhouse gasses to the atmosphere. In Greenland, the consequences of permafrost thaw have only recently been addressed, and predictions on its impact on the carbon budget are thus still highly uncertain. However, the fate of OC is not only determined by abiotic factors, but closely tied to microbial activity. We investigated eight soil profiles in northeast Greenland comprising two sites with typical tundra vegetation and one wet fen site. We assessed microbial community structure and diversity (SSU rRNA gene tag sequencing, quantification of bacteria, archaea and fungi), and measured hydrolytic and oxidative enzyme activities. Sampling site and thus abiotic factors had a significant impact on microbial community structure, diversity and activity, the wet fen site exhibiting higher potential enzyme activities and presumably being a hot spot for anaerobic degradation processes such as fermentation and methanogenesis. Lowest fungal to bacterial ratios were found in topsoils that had been relocated by cryoturbation ("buried topsoils"), resulting from a decrease in fungal abundance compared to recent ("unburied") topsoils. Actinobacteria (in particular Intrasporangiaceae) accounted for a major fraction of the microbial community in buried topsoils, but were only of minor abundance in all other soil horizons. It was indicated that the distribution pattern of Actinobacteria and a variety of other bacterial classes was related to the activity of phenol oxidases and peroxidases supporting the hypothesis that bacteria might resume the role of fungi in oxidative enzyme production and degradation of phenolic and other complex substrates in these soils. Our study sheds light on the highly diverse, but poorly-studied communities in permafrost-affected soils in Greenland and their role in OC degradation.

  20. Effects of Permafrost Degradation on Soil Hydrological Processes in Alpine Steppe on the Qinghai-Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    Yin Zhifang; Ouyang Hua; Yang Zhaoping

    2012-01-01

    Permafrost degradation is prevalent on the Qinghai-Ti-bet Plateau. This may lead to changes in water and heat transition in soils and thus affect the structure and function of ecosystems. In this paper, using the measured data of alpine steppe in Wud- aoliang assessed the model performance in simulating soil freezing and thawing processes. Comparison of the simulated results by simultaneous heat and water (SHAW) model to the measured data showed that SHAW model performed satisfactorily. Based on analyzing the simulated and predicted results, two points were obtained: (1) freezing and thawing of the active layer proceeded both from the soil surface downward. Compared with the freezing process, the thawing process was slower. The freezing period persisted in the surface layer (4 cm depth) for about 5 months; (2) in the next 50 years, frozen period would be shorten about 20 days in the top 100 cm depth while the thawing would start earlier 40 days than present. Soil water storage in the 0-60 cm would de- crease by 22% averagely, especially from June to August when the vegetation is at the dominating water consumed stage. Therefore, this kind of permafrost degradation as active layer freezing and thawing processes changes will reduce soil water content and thus influence those ecosystems above it.

  1. DUE PERMAFROST: A Circumpolar Remote Sensing Service for Permafrost - Evaluation Case Studies and Intercomparison with Regional Climate Model Simulations

    Science.gov (United States)

    Heim, B.; Bartsch, A.; Elger, K. K.; Rinke, A.; Matthes, H.; Zhou, X.; Klehmet, K.; Buchhorn, M.; Soliman, A. S.; Duguay, C. R.

    2013-12-01

    The objective of the ESA Data User Element DUE Permafrost project (https://www.ipf.tuwien.ac.at/permafrost/) was to establish a Remote Sensing Service for permafrost applications. Permafrost has been addressed as one of the Essential Climate Variables (ECVs) in the Global Climate Observing System (GCOS). Permafrost is a subground phenomenon but Earth Observation can provide permafrost-related indicators and geophysical parameters used in modelling and monitoring. Climate and permafrost modelers as well as field investigators are associated users including the International Permafrost Association (IPA). http://www.page21.eu/ The ESA DUE Permafrost project (2009-2012) developed a suite of remote sensing products indicative for the subsurface phenomenon permafrost: Land Surface Temperature (LST), Surface Soil Moisture (SSM), Surface Frozen and Thawed State (Freeze/Thaw), Terrain, Land Cover, and Surface Water. Snow parameters (Snow Extent and Snow Water Equivalent) are being developed through the DUE GlobSnow project (Global Snow Monitoring for Climate Research, 2008-2011). The final DUE Permafrost remote sensing products cover the years 2007 to 2011 with a circumpolar coverage (north of 50°N). The products were released in 2012, to be used to analyze the temporal dynamics and map the spatial patterns of permafrost indicators. Further information is available at www.ipf.tuwien.ac.at/ permafrost. The remote sensing service also supports the FP7 funded project PAGE21 - Changing Permafrost in the Arctic and its Global Effects in the 21st Century, http://www.page21.eu/. The primary programme providing various ground data for the evaluation is the Global Terrestrial Network for Permafrost (GTN-P) initiated by the International Permafrost Association (IPA). Ground data ranges from active layer- and snow depths, to air-, ground-, and borehole temperature data as well as soil moisture measurements and the description of landform and vegetation. The involvement of scientific

  2. 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....

  3. Permafrost collapse after shrub removal shifts tundra ecosystem to a methane source

    DEFF Research Database (Denmark)

    Nauta, Ake L.; Heijmans, Monique P.D.; Blok, Daan;

    2015-01-01

    Arctic tundra ecosystems are warming almost twice as fast as the global average1. Permafrost thaw and the resulting release of greenhouse gases from decomposing soil organic carbon have the potential to accelerate climate warming2,3. In recent decades, Arctic tundra ecosystems have changed rapidly4......, including expansion of woody vegetation5,6, in response to changing climate conditions. How such vegetation changes contribute to stabilization or destabilization of the permafrost is unknown. Here we present six years of field observations in a shrub removal experiment at a Siberian tundra site. Removing...... the shrub part of the vegetation initiated thawing of ice-rich permafrost, resulting in collapse of the originally elevated shrub patches into waterlogged depressions within five years. This thaw pond development shifted the plots from a methane sink into a methane source. The results of our field...

  4. Biodegradation of aliphatic vs. aromatic hydrocarbons in fertilized arctic soils

    Science.gov (United States)

    Braddock, J.F.

    1999-01-01

    A study was carried out to test a simple bioremediation treatment strategy in the Arctic and analyze the influence of fertilization the degradation of aliphatic and aromatic hydrocarbons, e.g., pristine, n-tetradecane, n-pentadecane, 2-methylnaphthalene, naphthalene, and acenaphthalene. The site was a coarse sand pad that once supported fuel storage tanks. Diesel-range organics concentrations were 250-860 mg/kg soil at the beginning of the study. Replicate field plots treated with fertilizer yielded final concentrations of 0, 50, 100, or 200 mg N/kg soil. Soil pH and soil-water potentials decreased due to fertilizer application. The addition of fertilizer considerably increased soil respiration potentials, but not the populations of microorganisms measured. Fertilizer addition also led to ??? 50% loss of measured aliphatic and aromatic hydrocarbons in surface and subsurface soils. For fertilized plots, hydrocarbon loss was not associated with the quantity of fertilizer added. Losses of aliphatic hydrocarbons were ascribed to biotic processes, while losses of aromatic hydrocarbons were due to biotic and abiotic processes.

  5. Indexing Permafrost Soil Organic Matter Degradation Using High-Resolution Mass Spectrometry.

    Science.gov (United States)

    Mann, Benjamin F; Chen, Hongmei; Herndon, Elizabeth M; Chu, Rosalie K; Tolic, Nikola; Portier, Evan F; Roy Chowdhury, Taniya; Robinson, Errol W; Callister, Stephen J; Wullschleger, Stan D; Graham, David E; Liang, Liyuan; Gu, Baohua

    2015-01-01

    Microbial degradation of soil organic matter (SOM) is a key process for terrestrial carbon cycling, although the molecular details of these transformations remain unclear. This study reports the application of ultrahigh resolution mass spectrometry to profile the molecular composition of SOM and its degradation during a simulated warming experiment. A soil sample, collected near Barrow, Alaska, USA, was subjected to a 40-day incubation under anoxic conditions and analyzed before and after the incubation to determine changes of SOM composition. A CHO index based on molecular C, H, and O data was utilized to codify SOM components according to their observed degradation potentials. Compounds with a CHO index score between -1 and 0 in a water-soluble fraction (WSF) demonstrated high degradation potential, with a highest shift of CHO index occurred in the N-containing group of compounds, while similar stoichiometries in a base-soluble fraction (BSF) did not. Additionally, compared with the classical H:C vs O:C van Krevelen diagram, CHO index allowed for direct visualization of the distribution of heteroatoms such as N in the identified SOM compounds. We demonstrate that CHO index is useful not only in characterizing arctic SOM at the molecular level but also enabling quantitative description of SOM degradation, thereby facilitating incorporation of the high resolution MS datasets to future mechanistic models of SOM degradation and prediction of greenhouse gas emissions.

  6. Indexing Permafrost Soil Organic Matter Degradation Using High-Resolution Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Mann, Benjamin F.; Chen, Hong-Mei; Herndon, Elizabeth M.; Chu, Rosalie K.; Tolic, Nikola; Portier, Evan; Chowdhury, Taniya R.; Robinson, Errol W.; Callister, Stephen J.; Wullschleger, Stan D.; Graham, David E.; Liang, Liyuan; Gu, Baohua

    2015-06-12

    Microbial degradation of soil organic matter (SOM) is a key process for terrestrial carbon cycling, although the molecular details of these transformations remain unclear. This study reports the application of ultrahigh resolution mass spectrometry to profile the molecular composition of SOM and its degradation during a simulated warming experiment. A soil sample, collected near Barrow, Alaska, USA, was subjected to a 40-day incubation under anoxic conditions and analyzed before and after the incubation to determine changes of SOM composition. A CHO index based on molecular C, H, and O data was utilized to codify SOM components according to their observed degradation potentials. Compounds with a CHO index score between –1 and 0 in a water-soluble fraction (WSF) demonstrated high degradation potential, with a highest shift of CHO index occurred in the N-containing group of compounds, while similar stoichiometries in a base-soluble fraction (BSF) did not. Additionally, compared with the classical H:C vs O:C van Krevelen diagram, CHO index allowed for direct visualization of the distribution of heteroatoms such as N in the identified SOM compounds. We demonstrate that CHO index is useful not only in characterizing arctic SOM at the molecular level but also enabling quantitative description of SOM degradation, thereby facilitating incorporation of the high resolution MS datasets to future mechanistic models of SOM degradation and prediction of greenhouse gas emissions.

  7. Indexing Permafrost Soil Organic Matter Degradation Using High-Resolution Mass Spectrometry.

    Directory of Open Access Journals (Sweden)

    Benjamin F Mann

    Full Text Available Microbial degradation of soil organic matter (SOM is a key process for terrestrial carbon cycling, although the molecular details of these transformations remain unclear. This study reports the application of ultrahigh resolution mass spectrometry to profile the molecular composition of SOM and its degradation during a simulated warming experiment. A soil sample, collected near Barrow, Alaska, USA, was subjected to a 40-day incubation under anoxic conditions and analyzed before and after the incubation to determine changes of SOM composition. A CHO index based on molecular C, H, and O data was utilized to codify SOM components according to their observed degradation potentials. Compounds with a CHO index score between -1 and 0 in a water-soluble fraction (WSF demonstrated high degradation potential, with a highest shift of CHO index occurred in the N-containing group of compounds, while similar stoichiometries in a base-soluble fraction (BSF did not. Additionally, compared with the classical H:C vs O:C van Krevelen diagram, CHO index allowed for direct visualization of the distribution of heteroatoms such as N in the identified SOM compounds. We demonstrate that CHO index is useful not only in characterizing arctic SOM at the molecular level but also enabling quantitative description of SOM degradation, thereby facilitating incorporation of the high resolution MS datasets to future mechanistic models of SOM degradation and prediction of greenhouse gas emissions.

  8. Indexing Permafrost Soil Organic Matter Degradation Using High-Resolution Mass Spectrometry

    Science.gov (United States)

    Herndon, Elizabeth M.; Chu, Rosalie K.; Tolic, Nikola; Portier, Evan F.; Roy Chowdhury, Taniya; Robinson, Errol W.; Callister, Stephen J.; Wullschleger, Stan D.; Graham, David E.; Liang, Liyuan; Gu, Baohua

    2015-01-01

    Microbial degradation of soil organic matter (SOM) is a key process for terrestrial carbon cycling, although the molecular details of these transformations remain unclear. This study reports the application of ultrahigh resolution mass spectrometry to profile the molecular composition of SOM and its degradation during a simulated warming experiment. A soil sample, collected near Barrow, Alaska, USA, was subjected to a 40-day incubation under anoxic conditions and analyzed before and after the incubation to determine changes of SOM composition. A CHO index based on molecular C, H, and O data was utilized to codify SOM components according to their observed degradation potentials. Compounds with a CHO index score between –1 and 0 in a water-soluble fraction (WSF) demonstrated high degradation potential, with a highest shift of CHO index occurred in the N-containing group of compounds, while similar stoichiometries in a base-soluble fraction (BSF) did not. Additionally, compared with the classical H:C vs O:C van Krevelen diagram, CHO index allowed for direct visualization of the distribution of heteroatoms such as N in the identified SOM compounds. We demonstrate that CHO index is useful not only in characterizing arctic SOM at the molecular level but also enabling quantitative description of SOM degradation, thereby facilitating incorporation of the high resolution MS datasets to future mechanistic models of SOM degradation and prediction of greenhouse gas emissions. PMID:26068586

  9. Western Arctic Coastal Plain, IFSAR-derived, Digital Surface Model. University of Alaska Fairbanks, Geophysical Institute Permafrost Laboratory (2013).

    Data.gov (United States)

    Arctic Landscape Conservation Cooperative — This dataset consists of a mosaic created from an Interferometric Synthetic Aperture Radar (IfSAR) derived digital surface model (DSM) acquired over the National...

  10. Using ground data of the Global Terrestrial Network of Permafrost (GTN-P) for the evaluation of ESA Data User Element (DUE) Permafrost remote sensing derived products

    Science.gov (United States)

    Elger, K.; Heim, B.; Bartsch, A.; Paulik, Ch.; Duguay, C.; Hachem, S.; Soliman, A.; Boike, J.; Langer, M.; Lantuit, H.

    2012-04-01

    Permafrost is one of the essential climate variables addressed by the Global Terrestrial Observing System (GCOS). Remote sensing data provide area-wide monitoring of e.g. surface temperatures or soil surface status (frozen or thawed state) in the Arctic and Subarctic, where ground data collection is difficult and restricted to local measurements at few monitoring sites. The task of the ESA Data User Element (DUE) Permafrost project is to build-up an Earth observation service for northern high-latitudinal permafrost applications with extensive involvement of the international permafrost research community (www.ipf.tuwien.ac.at/permafrost). The satellite-derived DUE Permafrost products are Land Surface Temperature, Surface Soil Moisture, Surface Frozen and Thawed State, Digital Elevation Model (locally as remote sensing product and circumpolar as non-remote sensing product) and Subsidence, and Land Cover. Land Surface Temperature, Surface Soil Moisture, and Surface Frozen and Thawed State will be provided for the circumpolar permafrost area north of 55° N with 25 km spatial resolution. In addition, regional products with higher spatial resolution were developed for five case study regions in different permafrost zones of the tundra and taiga (Laptev Sea [RU], Central Yakutia [RU], Western Siberia [RU], Alaska N-S transect, [US] Mackenzie River and Valley [CA]). This study shows the evaluation of two DUE Permafrost regional products, Land Surface Temperature and Surface Frozen and Thawed State, using freely available ground truth data from the Global Terrestrial Network of Permafrost (GTN-P) and monitoring data from the Russian-German Samoylov research station in the Lena River Delta (Central Siberia, RU). The GTN-P permafrost monitoring sites with their position in different permafrost zones are highly qualified for the validation of DUE Permafrost remote sensing products. Air and surface temperatures with high-temporal resolution from eleven GTN-P sites in Alaska

  11. Transpiration response of boreal forest plants to permafrost thaw

    Science.gov (United States)

    Cable, J.; Ogle, K.; Welker, J. M.

    2011-12-01

    Shifts in the rate and patterns of evapotranspiration with permafrost thaw, vegetation change, and altered climatic conditions are unknown in boreal systems. Specifically, the response of transpiration is not well understood but critical to quantify given its non-linear response to climate. We asked: what is the effect of permafrost thaw on the transpiration dynamics of sub-Arctic boreal plants? We utilized a Bayesian analysis approach to quantify the responses of plants located in areas with and without stable permafrost to current and antecedent vapor pressure deficit, soil moisture, soil temperature, and the prior year's soil temperature. We measured stomatal conductance (gs) on six species of plants over two summers. For the analysis, the plants were grouped into three functional types: deciduous shrubs, evergreen sub-shrubs, and black spruce trees. The model we constructed includes a VPD (current and antecedent) sensitivity term modeled as a function of soil moisture (current and antecedent), and a "base" gs term modeled as a function of current soil temperature (at different depths), thaw depth, and the prior growing season's soil temperature (for each month, May - September). Current VPD was more important early in the growing season, but antecedent VPD was more important later in the growing season. The memory of gs for antecedent VPD was ~ three weeks in the past. The daily trends were less resolved for the site with degrading permafrost. Deeper thaw resulted in higher sensitivity to VPD and higher gs, particularly at the site with stable permafrost. Deciduous shrubs showed the strongest effect. At the site with thawing permafrost, soil water positively affected the sensitivity of gs to VPD for the deciduous shrubs but had a negative effect on black spruce. Current soil moisture was important early in the growing season but antecedent moisture was important at the end. The site with thawing permafrost had a longer memory (two weeks) for antecedent moisture

  12. Thawing permafrost increases old soil and autotrophic respiration in tundra: partitioning ecosystem respiration using δ(13) C and ∆(14) C.

    Science.gov (United States)

    Hicks Pries, Caitlin E; Schuur, Edward A G; Crummer, Kathryn G

    2013-02-01

    Ecosystem respiration (Reco ) is one of the largest terrestrial carbon (C) fluxes. The effect of climate change on Reco depends on the responses of its autotrophic and heterotrophic components. How autotrophic and heterotrophic respiration sources respond to climate change is especially important in ecosystems underlain by permafrost. Permafrost ecosystems contain vast stores of soil C (1672 Pg) and are located in northern latitudes where climate change is accelerated. Warming will cause a positive feedback to climate change if heterotrophic respiration increases without corresponding increases in primary production. We quantified the response of autotrophic and heterotrophic respiration to permafrost thaw across the 2008 and 2009 growing seasons. We partitioned Reco using Δ(14) C and δ(13) C into four sources-two autotrophic (above - and belowground plant structures) and two heterotrophic (young and old soil). We sampled the Δ(14) C and δ(13) C of sources using incubations and the Δ(14) C and δ(13) C of Reco using field measurements. We then used a Bayesian mixing model to solve for the most likely contributions of each source to Reco . Autotrophic respiration ranged from 40 to 70% of Reco and was greatest at the height of the growing season. Old soil heterotrophic respiration ranged from 6 to 18% of Reco and was greatest where permafrost thaw was deepest. Overall, growing season fluxes of autotrophic and old soil heterotrophic respiration increased as permafrost thaw deepened. Areas with greater thaw also had the greatest primary production. Warming in permafrost ecosystems therefore leads to increased plant and old soil respiration that is initially compensated by increased net primary productivity. However, barring large shifts in plant community composition, future increases in old soil respiration will likely outpace productivity, resulting in a positive feedback to climate change.

  13. The effect of vegetation type and fire on permafrost thaw: An empirical test of a process based model

    Science.gov (United States)

    Thierry, Aaron; Estop-Aragones, Cristian; Fisher, James; Hartley, Iain; Murton, Julian; Phoenix, Gareth; Street, Lorna; Williams, Mathew

    2015-04-01

    As conditions become more favourable for plant growth in the high latitudes, most models predict that these areas will take up more carbon during the 21st century. However, vast stores of carbon are frozen in boreal and arctic permafrost, and warming may result in some of this carbon being released to the atmosphere. The recent inclusion of permafrost thaw in large-scale model simulations has suggested that the permafrost feedback could potentially substantially reduce the predicted global net uptake of carbon by terrestrial ecosystems, with major implications for the rate of climate change. However, large uncertainties remain in predicting rates of permafrost thaw and in determining the impacts of thaw in contrasting ecosystems, with many of the key processes missing from carbon-climate models. The role that different plant communities play in insulating soils and protecting permafrost is poorly quantified, with key groups such as mosses absent in many models. But it is thought that they may play a key role in determining permafrost resilience. In order to test the importance of these ecological processes we use a new specially acquired dataset from sites in the Canadian arctic to develop, parameterise and evaluate a detailed process-based model of vegetation-soil-permafrost interactions which includes an insulating moss understory. We tested the sensitivity of modelled active layer depth to a series of factors linked to fire disturbance, which is common in boreal permafrost areas. We show how simulations of active layer depth (ALD) respond to removals of (i) vascular vegetation, (ii) moss cover, and (iii) organic soil layers. We compare model responses to observed patterns from Canada. We also describe the sensitivity of our modelled ALD to changes in temperature and precipitation. We found that four parameters controlled most of the sensitivity in the modelled ALD, linked to conductivity of organic soils and mosses.

  14. Soil bacterial community composition altered by increased nutrient availability in Arctic tundra soils

    Directory of Open Access Journals (Sweden)

    Akihiro eKoyama

    2014-10-01

    Full Text Available The pool of soil organic carbon (SOC in the Arctic is disproportionally large compared to those in other biomes. This large quantity of SOC accumulated over millennia due to slow rates of decomposition relative to net primary productivity. Decomposition is constrained by low temperatures and nutrient concentrations, which limit soil microbial activity. We investigated how nutrients limit bacterial and fungal biomass and community composition in organic and mineral soils within moist acidic tussock tundra ecosystems. We sampled two experimental arrays of moist acidic tussock tundra that included fertilized and non-fertilized control plots. One array included plots that had been fertilized annually since 1989 and the other since 2006. Fertilization significantly altered overall bacterial community composition and reduced evenness, to a greater degree in organic than mineral soils, and in the 1989 compared to the 2006 site. The relative abundance of copiotrophic α-proteobacteria and β-proteobacteria was higher in fertilized than control soils, and oligotrophic Acidobacteria were less abundant in fertilized than control soils at the 1989 site. Fungal community composition was less sensitive to increased nutrient availability, and fungal responses to fertilization were not consistent between soil horizons and sites. We detected two ectomycorrhizal genera, Russula and Cortinarius spp., associated with shrubs. Their relative abundance was not affected by fertilization despite increased dominance of their host plants in the fertilized plots. Our results indicate that fertilization, which has been commonly used to simulate warming in Arctic tundra, has limited applicability for investigating fungal dynamics under warming.

  15. An underestimated methane sink in Arctic mineral soils

    Science.gov (United States)

    Oh, Y.; Medvigy, D.; Stackhouse, B. T.; Lau, M.; Onstott, T. C.; Jørgensen, C. J.; Elberling, B.; Emmerton, C. A.; St Louis, V. L.; Moch, J.

    2015-12-01

    Atmospheric methane has more than doubled since the industrial revolution, yet the sources and sinks are still poorly constrained. Though soil methane oxidation is the largest terrestrial methane sink, it is inadequately represented in current models. We have conducted laboratory analysis of mineral cryosol soils from Axel Heiberg Island in the Canadian high arctic. Microcosm experiments were carried out under varying environmental conditions and used to parameterize methane oxidation models. One-meter long intact soil cores were also obtained from Axel Heiberg Island and analyzed in the laboratory. A controlled core thawing experiment was carried out, and observed methane fluxes were compared to modeled methane fluxes. We find that accurate model simulation of methane fluxes needs to satisfy two requirements:(1) microbial biomass needs to be dynamically simulated, and (2) high-affinity methanotrophs need to be represented. With these 2 features, our model is able to reproduce observed temperature and soil moisture sensitivities of high affinity methanotrophs, which are twice as sensitive to temperature than the low affinity methanotrophs and are active under saturated moisture conditions. The model is also able to accurately reproduce the time rate of change of microbial oxidation of atmospheric methane. Finally, we discuss the remaining biases and uncertainties in the model, and the challenges of extending models from the laboratory scale to the landscape scale.

  16. Thermal state of permafrost in North America: A contribution to the international polar year

    Science.gov (United States)

    Smith, S.L.; Romanovsky, V.E.; Lewkowicz, A.G.; Burn, C.R.; Allard, M.; Clow, G.D.; Yoshikawa, K.; Throop, J.

    2010-01-01

    A snapshot of the thermal state of permafrost in northern North America during the International Polar Year (IPY) was developed using ground temperature data collected from 350 boreholes. More than half these were established during IPY to enhance the network in sparsely monitored regions. The measurement sites span a diverse range of ecoclimatic and geological conditions across the continent and are at various elevations within the Cordillera. The ground temperatures within the discontinuous permafrost zone are generally above -3°C, and range down to -15°C in the continuous zone. Ground temperature envelopes vary according to substrate, with shallow depths of zero annual amplitude for peat and mineral soils, and much greater depths for bedrock. New monitoring sites in the mountains of southern and central Yukon suggest that permafrost may be limited in extent. In concert with regional air temperatures, permafrost has generally been warming across North America for the past several decades, as indicated by measurements from the western Arctic since the 1970s and from parts of eastern Canada since the early 1990s. The rates of ground warming have been variable, but are generally greater north of the treeline. Latent heat effects in the southern discontinuous zone dominate the permafrost thermal regime close to 0°C and allow permafrost to persist under a warming climate. Consequently, the spatial diversity of permafrost thermal conditions is decreasing over time.

  17. The Impact of Global Warming on the Carbon Cycle of Arctic Permafrost: An Experimental and Field Based Study

    Energy Technology Data Exchange (ETDEWEB)

    Onstott, Tullis C [Princeton University; Pffifner, Susan M; Chourey, Karuna [Oak Ridge National Laboratory

    2014-11-07

    Our results to date indicate that CO2 and CH4 fluxes from organic poor, Arctic cryosols on Axel Heiberg Island are net CH4 sinks and CO2 emitters in contrast to organic-rich peat deposits at sub-Arctic latitudes. This is based upon field observations and a 1.5 year long thawing experiment performed upon one meter long intact cores. The results of the core thawing experiments are in good agreement with field measurements. Metagenomic, metatranscriptomic and metaproteomic analyses indicate that high affinity aerobic methanotrophs belong to the uncultivated USCalpha are present in <1% abundance in these cryosols are are active in the field during the summer and in the core thawing experiments. The methanotrophs are 100 times more abundant than the methanogens. As a result mineral cryosols, which comprise 87% of Arctic tundra, are net methane sinks. Their presence and activity may account for the discrepancies observed between the atmospheric methane concentrations observed in the Arctic predicted by climate models and the observed seasonal fluctuations and decadal trends. This has not been done yet.

  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. Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire

    DEFF Research Database (Denmark)

    Abbott, Benjamin W.; Jones, Jeremy B.; Schuur, Edward A. G.;

    2016-01-01

    -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...

  20. Plants impact structure and function of bacterial communities in Arctic soils

    NARCIS (Netherlands)

    Kumar, Manoj; Mannisto, Minna K.; van Elsas, Jan Dirk; Nissinen, Riitta M.

    2016-01-01

    Microorganisms are prime drivers of ecosystem functions in the Arctic, and they are essential for vegetation succession. However, very little is known about the phylogenetic and functional diversities of the bacterial communities associated with Arctic plants, especially in low organic matter soils.

  1. High biolability of ancient permafrost carbon upon thaw

    NARCIS (Netherlands)

    Vonk, Jorien E.; Mann, Paul J.; Davydov, Sergey; Davydova, Anna; Spencer, Robert G. M.; Schade, John; Sobczak, William V.; Zimov, Nikita; Zimov, Sergei; Bulygina, Ekaterina; Eglinton, Timothy I.; Holmes, Robert M.

    2013-01-01

    Ongoing climate warming in the Arctic will thaw permafrost and remobilize substantial terrestrial organic carbon (OC) pools. Around a quarter of northern permafrost OC resides in Siberian Yedoma deposits, the oldest form of permafrost carbon. However, our understanding of the degradation and fate of

  2. Estimation and extrapolation of soil properties in the Siberian tundra, using field spectroscopy

    NARCIS (Netherlands)

    Bartholomeus, H.; Schaepman-Strub, G.; Blok, D.; Udaltsov, S.; Sofronov, R.

    2010-01-01

    The Siberian tundra is a complex and sensitive ecosystem. Predicted global warming will be highest in the Arctic and will severely affect permafrost environments. Due to its large spatial extent and large stocks of soil organic carbon, changes to the carbon fluxes in the Arctic will have significant

  3. A microbial functional group-based module for simulating methane production and consumption: Application to an incubated permafrost soil

    Science.gov (United States)

    Xu, Xiaofeng; Elias, Dwayne A.; Graham, David E.; Phelps, Tommy J.; Carroll, Sue L.; Wullschleger, Stan D.; Thornton, Peter E.

    2015-07-01

    Accurately estimating methane (CH4) flux in terrestrial ecosystems is critically important for investigating and predicting biogeochemistry-climate feedbacks. Improved simulations of CH4 flux require explicit representations of the microbial processes that account for CH4 dynamics. A microbial functional group-based module was developed, building on the decomposition subroutine of the Community Land Model 4.5. This module considers four key mechanisms for CH4 production and consumption: methanogenesis from acetate or from single-carbon compounds and CH4 oxidation using molecular oxygen or other inorganic electron acceptors. Four microbial functional groups perform these processes: acetoclastic methanogens, hydrogenotrophic methanogens, aerobic methanotrophs, and anaerobic methanotrophs. This module was used to simulate dynamics of carbon dioxide (CO2) and CH4 concentrations from an incubation experiment with permafrost soils. The results show that the model captures the dynamics of CO2 and CH4 concentrations in microcosms with top soils, mineral layer soils, and permafrost soils under natural and saturated moisture conditions and three temperature conditions of -2°C, 3°C, and 5°C (R2 > 0.67 P temperature conditions. Sensitivity analysis confirmed the importance of acetic acid's direct contribution as substrate and indirect effects through pH feedback on CO2 and CH4 production and consumption. This study suggests that representing the microbial mechanisms is critical for modeling CH4 production and consumption; it is urgent to incorporate microbial mechanisms into Earth system models for better predicting trace gas dynamics and the behavior of the climate system.

  4. International Field School on Permafrost, Polar Urals, 2012

    Science.gov (United States)

    Streletskiy, D. A.; Grebenets, V.; Ivanov, M.; Sheinkman, V.; Shiklomanov, N. I.; Shmelev, D.

    2012-12-01

    The international field school on permafrost was held in the Polar Urals region from June, 30 to July 9, 2012 right after the Tenth International Conference on Permafrost which was held in Salekhard, Russia. The travel and accommodation support generously provided by government of Yamal-Nenets Autonomous Region allowed participation of 150 permafrost young research scientists, out of which 35 students from seven countries participated in the field school. The field school was organized under umbrella of International Permafrost Association and Permafrost Young Research Network. The students represented diverse educational backgrounds including hydrologists, engineers, geologists, soil scientists, geocryologists, glaciologists and geomorphologists. The base school camp was located near the Harp settlement in the vicinity of Polar Urals foothills. This unique location presented an opportunity to study a diversity of cryogenic processes and permafrost conditions characteristic for mountain and plain regions as well as transition between glacial and periglacial environments. A series of excursions was organized according to the following topics: structural geology of the Polar Urals and West Siberian Plain (Chromite mine "Centralnaya" and Core Storage in Labitnangy city); quaternary geomorphology (investigation of moraine complexes and glacial conditions of Ronamantikov and Topographov glaciers); principles of construction and maintains of structures built on permafrost (Labitnangy city and Obskaya-Bovanenkovo Railroad); methods of temperature and active-layer monitoring in tundra and forest-tundra; cryosols and soil formation in diverse landscape condition; periglacial geomorphology; types of ground ice, etc. Every evening students and professors gave a series of presentations on climate, vegetation, hydrology, soil conditions, permafrost and cryogenic processes of the region as well as on history, economic development, endogenous population of the Siberia and the

  5. Inferred gas hydrate and permafrost stability history models linked to climate change in the Beaufort-Mackenzie Basin, Arctic Canada

    Directory of Open Access Journals (Sweden)

    J. Majorowicz

    2012-03-01

    Full Text Available Atmospheric methane from episodic gas hydrate (GH destabilization, the "clathrate gun" hypothesis, is proposed to affect past climates, possibly since the Phanerozoic began or earlier. In the terrestrial Beaufort-Mackenzie Basin (BMB, GHs occur commonly below thick ice-bearing permafrost (IBP, but they are rare within it. Two end-member GH models, where gas is either trapped conventionally (Case 1 or where it is trapped dynamically by GH formation (Case 2, were simulated using profile (1-D models and a 14 Myr ground surface temperature (GST history based on marine isotopic data, adjusted to the study setting, constrained by deep heat flow, sedimentary succession conductivity, and observed IBP and Type I GH contacts in Mallik wells. Models consider latent heat effects throughout the IBP and GH intervals. Case 1 GHs formed at ~0.9 km depth only ~1 Myr ago by in situ transformation of conventionally trapped natural gas. Case 2 GHs begin to form at ~290–300 m ~6 Myr ago in the absence of lithological migration barriers. During glacial intervals Case 2 GH layers expand both downward and upward as the permafrost grows downward through and intercalated with GHs. The distinctive model results suggest that most BMB GHs resemble Case 1 models, based on the observed distinct and separate occurrences of GHs and IBP and the lack of observed GH intercalations in IBP. Case 2 GHs formed >255 m, below a persistent ice-filled permafrost layer that is as effective a seal to upward methane migration as are Case 1 lithological seals. All models respond to GST variations, but in a delayed and muted manner such that GH layers continue to grow even as the GST begins to increase. The models show that the GH stability zone history is buffered strongly by IBP during the interglacials. Thick IBP and GHs could have persisted since ~1.0 Myr ago and ~4.0 Myr ago for Cases 1 and 2, respectively. Offshore BMB IBP and GHs formed terrestrially during Pleistocene sea level low

  6. The impacts of recent permafrost thaw on land-atmosphere greenhouse gas exchange

    Science.gov (United States)

    Hayes, Daniel J.; Kicklighter, David W.; McGuire, Anthony; Chen, Min; Zhuang, Qianlai; Yuan, Fengming; Melillo, Jerry M.; Wullschleger, Stan D.

    2014-01-01

    Permafrost thaw and the subsequent mobilization of carbon (C) stored in previously frozen soil organic matter (SOM) have the potential to be a strong positive feedback to climate. As the northern permafrost region experiences as much as a doubling of the rate of warming as the rest of the Earth, the vast amount of C in permafrost soils is vulnerable to thaw, decomposition and release as atmospheric greenhouse gases. Diagnostic and predictive estimates of high-latitude terrestrial C fluxes vary widely among different models depending on how dynamics in permafrost, and the seasonally thawed 'active layer' above it, are represented. Here, we employ a process-based model simulation experiment to assess the net effect of active layer dynamics on this 'permafrost carbon feedback' in recent decades, from 1970 to 2006, over the circumpolar domain of continuous and discontinuous permafrost. Over this time period, the model estimates a mean increase of 6.8 cm in active layer thickness across the domain, which exposes a total of 11.6 Pg C of thawed SOM to decomposition. According to our simulation experiment, mobilization of this previously frozen C results in an estimated cumulative net source of 3.7 Pg C to the atmosphere since 1970 directly tied to active layer dynamics. Enhanced decomposition from the newly exposed SOM accounts for the release of both CO2 (4.0 Pg C) and CH4 (0.03 Pg C), but is partially compensated by CO2 uptake (0.3 Pg C) associated with enhanced net primary production of vegetation. This estimated net C transfer to the atmosphere from permafrost thaw represents a significant factor in the overall ecosystem carbon budget of the Pan-Arctic, and a non-trivial additional contribution on top of the combined fossil fuel emissions from the eight Arctic nations over this time period.

  7. Quantifying the effect of lichen and bryophyte cover on permafrost soil within a global land surface model

    Science.gov (United States)

    Porada, Philipp; Ekici, Altug; Beer, Christian

    2016-04-01

    Vegetation near the surface, such as bryophytes and lichens, has an insulating effect on the soil at high latitudes and it can therefore protect permafrost conditions. Warming due to climate change, however, may change the average surface coverage of bryophytes and lichens. This can result in permafrost thawing associated with a release of soil carbon to the atmosphere, which may lead to a positive feedback on atmospheric CO2. Thus, it is important to predict how the bryophyte and lichen cover at high latitudes will react to environmental change. However, current global land surface models so far contain mostly empirical approaches to represent bryophytes and lichens, which makes it impractical to predict their future state and function. For this reason, we integrate a process-based model of bryophyte and lichen growth into the global land surface model JSBACH. We explicitly represent dynamic thermal properties of the bryophyte and lichen cover and their relation to climate. Subsequently, we compare simulations with and without bryophyte and lichen cover to quantify the insulating effect. We estimate an annual average cooling effect of the bryophyte and lichen cover of 2.7 K on topsoil temperature for the northern high latitudes under current climate. Locally, the cooling may reach up to 5.7 K. Moreover, we show that neglecting dynamic properties of the bryophyte and lichen cover by using a simple, empirical scheme only results in an average cooling of around 0.5 K. This suggests that bryophytes and lichens have a significant impact on soil temperature in high-latitude ecosystems and also that a process-based description of their thermal properties is necessary for a realistic representation of the cooling effect.

  8. Terrestrial Permafrost Models of Martian Habitats and Inhabitants

    Science.gov (United States)

    Gilichinsky, D.

    2011-12-01

    Martian permafrost is still 100 times older. Only one terrestrial environment is close to Mars in age - volcanoes in permafrost areas. The age of volcanic deposits frozen after eruption is much younger than the age of surrounding permafrost. Culture- and culture-independent methods show the presence of viable thermophiles and their genes within pyroclastic frozen material on Deception Island, Antarctica and Kamchatka peninsula. These bacteria and archeae have not been found in permafrost outside the volcanic areas. The only way for thermophiles to get into frozen soil is through deposition during eruption, i.e. the catastrophic geological events transport microbes from the depths to the surface and they survive at subzero temperatures. The past activity of Martian volcanoes periodically burned through the frozen strata and products of eruptions rose from the depths to the surface and froze. Images taken by the Stereo Camera on board the Mars Express discovered volcanoes 2-15Myr old that date back to ages close to permafrost on Earth. Terrestrial communities might serve as a model of inhabitants for these young volcanoes. 3. The only opportunity for free water on Mars is the overcooled water brines, and halo/psychrophilc community of Arctic cryopegs, sandwiched within permafrost, represents a plausible prototype for Martian microbial life.

  9. Transformation Pathways through the Land-water Geosphere in Permafrost Regions

    Science.gov (United States)

    Destouni, G.

    2014-12-01

    Arctic land-water undergoes and participates in multiple climate-driven and other (natural and direct human-driven) environmental exchanges and changes (Figure 1). A bits-and-pieces approach to these may miss essential aspects of change propagation and transformation by land-water across its multiple components (soil water, groundwater, hyporheic water, streams/rivers, wetlands and lakes) and from/to other geospheres (atmosphere and its climate change drivers, cryosphere and its permafrost segment, as well as the anthroposphere/technosphere, geosphere/pedosphere, marine hydrosphere and biosphere). This paper synthesizes results from recent modeling and observational studies of land-water flow and dissolved carbon transport in permafrost regions, departing from a new conceptualization of the land-water geosphere as a scale-free catchment-wise organized system (Figure 1), emphasizing several key new system aspects compared to traditional hydrosphere/water cycle view. Among these new aspects, we particularly investigate here the role of land-water flow and transport pathways as system coupling agents, with focus on their variability and change with varying permafrost conditions and permafrost thaw in a warming climate. Utilizing the conceptualization of land-water as a continuous yet structured geosphere, following the proposed flow-transport pathways of change propagation-transformation, we identify patterns of permafrost-related and other changes in Arctic hydrology.

  10. Can We Avoid the Permafrost Carbon Tipping Point?

    Science.gov (United States)

    Schaefer, K. M.; Zhang, T.; Bruhwiler, L.; Barrett, A. P.; Li, Z.

    2011-12-01

    If we reduce fossil fuel emissions and slow the Arctic warming rate, can we delay or even avoid the permafrost carbon tipping point? Permafrost currently contains about 1466 Gt of carbon frozen during or since the last ice age. The permafrost carbon tipping point occurs when the release of carbon from thawing permafrost overpowers enhanced uptake due to warmer temperatures. The tipping point indicates when the Arctic irreversibly changes from a carbon sink to a source relative to the atmosphere and marks the start of the Permafrost Carbon Feedback. The tipping point is irreversible because once the carbon thaws and decays into the atmosphere, there is no way to put the carbon back into the permafrost. Projections based on the A1B IPCC scenario indicate that the PCF tipping point will occur between 2020 and 2030, with a total of 190±64 Gt of carbon released into the atmosphere by 2300. We ran a series of model projections out to 2300 based on the A1B scenario, but capped emissions at various levels, each representing a different overall Arctic warming. We present the area of permafrost lost, the permafrost carbon tipping point, and total permafrost carbon flux as a function of Arctic temperature increase. We show the maximum allowed Arctic temperature increase before initiating the permafrost carbon feedback.

  11. A new data set for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region

    Science.gov (United States)

    Hugelius, G.; Bockheim, J.G.; Camill, P.; Elberling, B.; Grosse, G.; Harden, J.W.; Johnson, K.; Jorgenson, T.; Koven, C.D.; Kuhry, P.; Michaelson, G.; Mishra, U.; Palmtag, J.; Ping, C.-L.; O'Donnell, J.; Schirrmeister, L.; Schuur, E.A.G.; Sheng, Y.; Smith, L.C.; Strauss, J.; Yu, Z.

    2013-01-01

    High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of 18.7 × 106 km2). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to calculate SOC storage to the reference depths 0–30 cm and 0–100 cm (based on 1778 pedons). It has been shown that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100–300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m-2) in deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100–200 cm (524 pedons) and 200–300 cm (356 pedons) depth ranges. These pedons have been grouped into the North American and Eurasian sectors and the mean SOC storage for different soil taxa (subdivided into Gelisols including the sub-orders Histels, Turbels, Orthels, permafrost-free Histosols, and permafrost-free mineral soil orders) has been added to the updated NCSCDv2. The updated version of the data set is freely available online in different file formats and spatial resolutions that enable spatially explicit applications in GIS mapping and terrestrial ecosystem models. While this newly compiled data set adds to our knowledge of SOC in the 100–300 cm depth range, it also reveals that large uncertainties remain. Identified data gaps include spatial coverage of deep (> 100 cm) pedons in many regions as well as the spatial extent of areas

  12. Permafrost and gas hydrate related methane release in the Arctic and its impact on climate change - European cooperation for long-term monitoring: COST Action PERGAMON (www.cost-pergamon.eu)

    Science.gov (United States)

    Greinert, Jens; Treude, Tina; Members, Pergamon

    2010-05-01

    The Arctic is a key area in our warming world as massive releases of terrestrial and oceanic methane could increase atmospheric methane concentrations much faster than expected. The vast Arctic shelf might become a major emitter of methane in the future. Only a few projects are engaged in research on methane seepage in this area. The exchange of information about ongoing and planned activities in the Arctic with respect to gas hydrate destabilization and permafrost thawing is low within the EU and almost non-existent at an international level. The aim of the COST Action PERGAMON is to promote networking internationally within the EU and beyond: data integration of terrestrial studies from wetlands and permafrost regions marine research on gas release from seeps due to decomposing gas hydrate and/or permafrost melting and atmospheric investigations carried out by monitoring stations and via satellite is urgently needed to achieve a better understanding of methane emission processes in high latitude areas. The "official" main objective of PERGAMON is to quantify the methane input from marine and terrestrial sources into the atmosphere in the Arctic region, and ultimately to evaluate the impact of Arctic methane seepage on the global climate. This will be achieved by studying the origin and type of occurrence (dissolved/free gas, gas hydrate) of different methane sources (both on land and in the sub-seabed) as well as methane migration mechanisms, biogeochemical turnover, release mechanisms, and finally by quantifying the flux into the atmosphere. Biannual meetings and open workshops/conferences that will be announced throughout the scientific community serve as a platform to exchange and proliferate knowledge on methane in the Arctic. At present, fourteeen European countries are partners in PERGAMON, several non-COST country institutions are currently applying to participate (e.g. the US and Russia). PERGAMON aims to be open for new members, suggestions and input at

  13. Nearing the cold-arid limits of microbial life in permafrost of an upper dry valley, Antarctica.

    Science.gov (United States)

    Goordial, Jacqueline; Davila, Alfonso; Lacelle, Denis; Pollard, Wayne; Marinova, Margarita M; Greer, Charles W; DiRuggiero, Jocelyn; McKay, Christopher P; Whyte, Lyle G

    2016-07-01

    Some of the coldest and driest permafrost soils on Earth are located in the high-elevation McMurdo Dry Valleys (MDVs) of Antarctica, but little is known about the permafrost microbial communities other than that microorganisms are present in these valleys. Here, we describe the microbiology and habitable conditions of highly unique dry and ice-cemented permafrost in University Valley, one of the coldest and driest regions in the MDVs (1700 m above sea level; mean temperature -23 °C; no degree days above freezing), where the ice in permafrost originates from vapour deposition rather than liquid water. We found that culturable and total microbial biomass in University Valley was extremely low, and microbial activity under ambient conditions was undetectable. Our results contrast with reports from the lower-elevation Dry Valleys and Arctic permafrost soils where active microbial populations are found, suggesting that the combination of severe cold, aridity, oligotrophy of University Valley permafrost soils severely limit microbial activity and survival.

  14. Changing Export of Dissolved Black Carbon from Arctic Rivers

    Science.gov (United States)

    Stubbins, A.; Spencer, R. G.; Mann, P. J.; Dittmar, T.; Niggemann, J.; Holmes, R. M.; McClelland, J. W.

    2014-12-01

    Arctic rivers carry black carbon (BC) from Arctic soils to the ocean, linking two of the largest carbon stores on Earth. Wildfires have charred biomass since land plants emerged. BC, a refractory component of char, has accumulated in soils. In the oceans, dissolved BC (DBC) has also accumulated. Here we use samples and data collected as part of the long-term, high temporal resolution Arctic Great Rivers Observatory to model export of DBC from the six largest Arctic Rivers. Scaling to the pan-Arctic catchment, we report that ~3 million tons of DBC are delivered to the Arctic Ocean each year, which is ~8% of dissolved organic carbon loads to the Arctic Ocean. We suggest the transfer of Arctic river DBC to areas of deep water formation is a major source of DBC to the deep ocean carbon store. As the Arctic warms, greater wildfire occurrence is expected to produce more BC and changing hydrology and permafrost thaw to promote DBC export. Thus, the transfer of BC from Arctic soils to the ocean is predicted to increase.

  15. Estimating the near-surface permafrost-carbon feedback on global warming

    Directory of Open Access Journals (Sweden)

    T. Schneider von Deimling

    2012-02-01

    Full Text Available Thawing of permafrost and the associated release of carbon constitutes a positive feedback in the climate system, elevating the effect of anthropogenic GHG emissions on global-mean temperatures. Multiple factors have hindered the quantification of this feedback, which was not included in climate carbon-cycle models which participated in recent model intercomparisons (such as the Coupled Carbon Cycle Climate Model Intercomparison Project – C4MIP . There are considerable uncertainties in the rate and extent of permafrost thaw, the hydrological and vegetation response to permafrost thaw, the decomposition timescales of freshly thawed organic material, the proportion of soil carbon that might be emitted as carbon dioxide via aerobic decomposition or as methane via anaerobic decomposition, and in the magnitude of the high latitude amplification of global warming that will drive permafrost degradation. Additionally, there are extensive and poorly characterized regional heterogeneities in soil properties, carbon content, and hydrology. Here, we couple a new permafrost module to a reduced complexity carbon-cycle climate model, which allows us to perform a large ensemble of simulations. The ensemble is designed to span the uncertainties listed above and thereby the results provide an estimate of the potential strength of the feedback from newly thawed permafrost carbon. For the high CO2 concentration scenario (RCP8.5, 33–114 GtC (giga tons of Carbon are released by 2100 (68 % uncertainty range. This leads to an additional warming of 0.04–0.23 °C. Though projected 21st century permafrost carbon emissions are relatively modest, ongoing permafrost thaw and slow but steady soil carbon decomposition means that, by 2300, about half of the potentially vulnerable permafrost carbon stock in the upper 3 m of soil layer (600–1000 GtC could be released as CO2, with an extra 1–4 % being released as methane. Our results also

  16. Demequina lutea sp. nov., isolated from a high Arctic permafrost soil

    DEFF Research Database (Denmark)

    Finster, Kai; Herbert, Rodney Andrew; Kjeldsen, Kasper Urup

    2009-01-01

    up to 2 % NaCl (w/v) in the growth medium. Growth under anaerobic conditions was slow and weak. The peptidoglycan of both isolates was of the A4β type with L-ornithine as the diamino acid and serine as a component of the interpeptide bridge with either D-aspartate (SV45T) or D-glutamate (SV47...... the name Demequina lutea sp. nov. is proposed. The type strain is SV45T (=LMG 24795T =DSM 19970T)....

  17. Functional characterization of bacteria isolated from ancient arctic soil exposes diverse resistance mechanisms to modern antibiotics.

    Science.gov (United States)

    Perron, Gabriel G; Whyte, Lyle; Turnbaugh, Peter J; Goordial, Jacqueline; Hanage, William P; Dantas, Gautam; Desai, Michael M

    2015-01-01

    Using functional metagenomics to study the resistomes of bacterial communities isolated from different layers of the Canadian high Arctic permafrost, we show that microbial communities harbored diverse resistance mechanisms at least 5,000 years ago. Among bacteria sampled from the ancient layers of a permafrost core, we isolated eight genes conferring clinical levels of resistance against aminoglycoside, β-lactam and tetracycline antibiotics that are naturally produced by microorganisms. Among these resistance genes, four also conferred resistance against amikacin, a modern semi-synthetic antibiotic that does not naturally occur in microorganisms. In bacteria sampled from the overlaying active layer, we isolated ten different genes conferring resistance to all six antibiotics tested in this study, including aminoglycoside, β-lactam and tetracycline variants that are naturally produced by microorganisms as well as semi-synthetic variants produced in the laboratory. On average, we found that resistance genes found in permafrost bacteria conferred lower levels of resistance against clinically relevant antibiotics than resistance genes sampled from the active layer. Our results demonstrate that antibiotic resistance genes were functionally diverse prior to the anthropogenic use of antibiotics, contributing to the evolution of natural reservoirs of resistance genes.

  18. Food and soil-borne Penicillia in Arctic environments: Chemical diversity

    DEFF Research Database (Denmark)

    Frisvad, Jens Christian

    Penicillia are very common inhabitants of cold environments, including arctic soil, plants, animals, and foods. We have investigated the mycobiota of Greenland inland ice and soil, and found a very unique and pronounced diversity among the Penicillia. Nearly all species were new to science....... The species found in inland ice were both of the soil-borne type, and Penicillia that grow and sporulate well at 25°C. The latter group of Penicillia have been found earlier in refrigerated foods, including P. nordicum, and in glacier ice and melting water from Svalbard (se Sonjak et al., this conference......). This “food-borne group” of arctic fungi also contained some new species, but not as many as in arctic soil. The chemical diversity of the Penicillium species was remarkably high and in most cases even larger than the chemical diversity of Penicillia in the tropics. Several new secondary metabolites were...

  19. Permafrost in Space: first results of experiment "EXOBIOFROST"

    Science.gov (United States)

    Spirina, Elena; Rivkina, Elizaveta; Shmakova, Lubov; Mironov, Vasiliy; Shatilovich, Anastasiya

    Experiment "EXOBIOFROST" was conducted as part of BION-M project of Russian Space Agency. We investigated a response of microbial complexes, including the pure cultures of microorganisms isolated from permafrost and the initial permafrost samples of different origin and age on space conditions. Duration of experiment was 1 month, from April, 19 to May, 19, 2013. All samples were investigated before and after the space flight. For the experiment we selected five samples of permafrost soil from Kolyma-Indigirka Lowland and Antarctica, and also the cultures of microorganisms: Exiguobacterium sibiricum - gram negative bacteria; Colpoda Steinii and Exocolpoda augustini — ciliates, and two strains of Acanthamoeba castelliane. Studies have revealed differences in structure and composition of microbial communities in control and in post-flight samples. All Arctic samples were characterized by a significant, 3-5 orders of magnitude, increase in the number of microorganisms compared to the control samples. However, there is a marked reduction in the amount of extracted DNA in post-flight permafrost samples. Post-flight analysis of ciliates, Colpoda Steinii and Exocolpoda augustini, revealed that 70-97% of cysts are damaged. In general, the primary post-flight analysis and a comparison with the control samples showed that the modern tundra colpoda more resistant to space conditions than they from the ancient permafrost sediments and strain of Colpoda steinii more resistant than the strain Exocolpoda augustini. Post-flight analysis of Acanthamoeba castelliane showed presence of viable cysts capable of excystation. Thus, we can conclude that the experiment "EXOBIOFROST" conducted in open space on the apparatus BION-M №1 does not prove fatal to permafrost microorganisms.

  20. The Global Terrestrial Network for Permafrost Database: metadata statistics and prospective analysis on future permafrost temperature and active layer depth monitoring site distribution

    Directory of Open Access Journals (Sweden)

    B. K. Biskaborn

    2015-03-01

    Full Text Available The Global Terrestrial Network for Permafrost (GTN-P provides the first dynamic database associated with the Thermal State of Permafrost (TSP and the Circumpolar Active Layer Monitoring (CALM programs, which extensively collect permafrost temperature and active layer thickness data from Arctic, Antarctic and Mountain permafrost regions. The purpose of the database is to establish an "early warning system" for the consequences of climate change in permafrost regions and to provide standardized thermal permafrost data to global models. In this paper we perform statistical analysis of the GTN-P metadata aiming to identify the spatial gaps in the GTN-P site distribution in relation to climate-effective environmental parameters. We describe the concept and structure of the Data Management System in regard to user operability, data transfer and data policy. We outline data sources and data processing including quality control strategies. Assessment of the metadata and data quality reveals 63% metadata completeness at active layer sites and 50% metadata completeness for boreholes. Voronoi Tessellation Analysis on the spatial sample distribution of boreholes and active layer measurement sites quantifies the distribution inhomogeneity and provides potential locations of additional permafrost research sites to improve the representativeness of thermal monitoring across areas underlain by permafrost. The depth distribution of the boreholes reveals that 73% are shallower than 25 m and 27% are deeper, reaching a maximum of 1 km depth. Comparison of the GTN-P site distribution with permafrost zones, soil organic carbon contents and vegetation types exhibits different local to regional monitoring situations on maps. Preferential slope orientation at the sites most likely causes a bias in the temperature monitoring and should be taken into account when using the data for global models. The distribution of GTN-P sites within zones of projected temperature change

  1. The Global Terrestrial Network for Permafrost Database: metadata statistics and prospective analysis on future permafrost temperature and active layer depth monitoring site distribution

    Science.gov (United States)

    Biskaborn, B. K.; Lanckman, J.-P.; Lantuit, H.; Elger, K.; Streletskiy, D. A.; Cable, W. L.; Romanovsky, V. E.

    2015-03-01

    The Global Terrestrial Network for Permafrost (GTN-P) provides the first dynamic database associated with the Thermal State of Permafrost (TSP) and the Circumpolar Active Layer Monitoring (CALM) programs, which extensively collect permafrost temperature and active layer thickness data from Arctic, Antarctic and Mountain permafrost regions. The purpose of the database is to establish an "early warning system" for the consequences of climate change in permafrost regions and to provide standardized thermal permafrost data to global models. In this paper we perform statistical analysis of the GTN-P metadata aiming to identify the spatial gaps in the GTN-P site distribution in relation to climate-effective environmental parameters. We describe the concept and structure of the Data Management System in regard to user operability, data transfer and data policy. We outline data sources and data processing including quality control strategies. Assessment of the metadata and data quality reveals 63% metadata completeness at active layer sites and 50% metadata completeness for boreholes. Voronoi Tessellation Analysis on the spatial sample distribution of boreholes and active layer measurement sites quantifies the distribution inhomogeneity and provides potential locations of additional permafrost research sites to improve the representativeness of thermal monitoring across areas underlain by permafrost. The depth distribution of the boreholes reveals that 73% are shallower than 25 m and 27% are deeper, reaching a maximum of 1 km depth. Comparison of the GTN-P site distribution with permafrost zones, soil organic carbon contents and vegetation types exhibits different local to regional monitoring situations on maps. Preferential slope orientation at the sites most likely causes a bias in the temperature monitoring and should be taken into account when using the data for global models. The distribution of GTN-P sites within zones of projected temperature change show a high

  2. The role of permafrost and soil water in distribution of alpine grassland and its NDVI dynamics on the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Wang, Xiaoyun; Yi, Shuhua; Wu, Qingbai; Yang, Kun; Ding, Yongjian

    2016-12-01

    Soil temperature and soil water are two important factors controlling vegetation growth. Climate warming and associated permafrost degradation might change these soil conditions and affect alpine grassland on the Qinghai-Tibetan Plateau. However, our current understanding of the role of soil temperature and water at the plateau scale is inadequate. In this study, we used plateau scale soil water content, frozen soil type, vegetation index and land surface temperature datasets to investigate the spatial distribution, limiting factors of vegetation growth and normalized difference vegetation index (NDVI) changing trends in two major alpine grasslands, alpine meadow and alpine steppe, in relation to soil temperature and soil water conditions. Our results showed that: 1) alpine meadow is mainly distributed in seasonal frozen soil areas (55.90% of alpine meadow) with a soil water content between 0.15 and 0.25 m3/m3 and alpine steppe is mainly found in seasonal frozen and sub-stable permafrost areas (69.38% of alpine steppe) with a soil water content between 0.05 and 0.20 m3/m3; 2) at the plateau scale, there were 35.6% (more in colder regions) of alpine meadow pixels and 33.6% (more in wetter regions) of alpine steppe pixels having increase NDVI changing trends during 1982-2012, respectively; and the values having decrease NDVI changing trends are 7.3% and 9.7%, respectively; and 3) the vegetation growth of alpine meadow is mainly limited by soil temperature, while that of alpine steppe is limited by both soil temperature and soil water. We also find the limiting factors of temperature or water can only explain models to consider other factors, such as grazing, erosion and soil texture, among others, in addition to soil temperature and water to make proper projections when simulating the responses of vegetation growth to climate warming in alpine grasslands with different hydro-thermal conditions.

  3. Collaboration in Education: International Field Class on Permafrost

    Science.gov (United States)

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

    2011-12-01

    Field work is a dominant research component in the earth sciences. Understanding and proper use of field methods can enhance the quality of research, while lack of understanding in acquiring data can lead to misleading interpretation of results. Early involvement in field work helps students to bridge the gap between theoretical knowledge and practical applications and to be better prepared for future jobs. However, many University curriculums lack adequate, required field methods courses. Presented are results of collaboration between the George Washington and Moscow State Universities in organization of field courses on Arctic physical and social environments. The latest field course took place in summer 2011 in the Central Siberian region and is a part of the International Permafrost Association education and outreach effort initiated during International Polar Year. The 25 day course involved fifteen Russian and US students who traveled from Moscow to Krasnoyarsk, and then along Yenisey river to Norilsk. This route was chosen as having diversity of natural conditions and variety of economic, engineering, and demographic problems associated with development. The main goal of the class was to investigate permafrost conditions of Central Siberia; dynamics of upper permafrost due to changing climate and under anthropogenic influence; and to understand factors responsible for the diversity of permafrost conditions in the region. The students and instructors were required to make presentations on a variety of topics focusing on the region or research methods, such as climate, vegetation, hydrology, history of development, economics, remote sensing, etc. The emphasis in the field was made on understanding permafrost in relation to other components of the natural system. For example, landscape conditions (including microclimatic, biogeographic and pedologic conditions) were described at every site located in natural settings. Sites located in settlements were evaluated

  4. Simulation of permafrost and seasonal thaw depth in the JULES land surface scheme

    Directory of Open Access Journals (Sweden)

    R. Dankers

    2011-04-01

    Full Text Available Land surface models (LSMs need to be able to simulate realistically the dynamics of permafrost and frozen ground. In this paper we evaluate the performance of the LSM JULES (Joint UK Land Environment Simulator, the stand-alone version of the land surface scheme used in Hadley Centre climate models, in simulating the large-scale distribution of surface permafrost. In particular we look at how well the model is able to simulate the seasonal thaw depth or active layer thickness (ALT. We performed a number of experiments driven by observation-based climate datasets. Visually there is a very good agreement between areas with permafrost in JULES and known permafrost distribution in the Northern Hemisphere, and the model captures 97% of the area where the permafrost coverage is at least 50% of the grid cell. However, the model overestimates the total extent as it also simulates permafrost where it occurs sporadically or only in isolated patches. Consistent with this we find a cold bias in the simulated soil temperatures, especially in winter. However, when compared with observations on end-of-season thaw depth from around the Arctic, the ALT in JULES is generally too deep. Additional runs at three sites in Alaska demonstrate how uncertainties in the precipitation input affect the simulation of soil temperatures by affecting the thickness of the snowpack and therefore the thermal insulation in winter. In addition, changes in soil moisture content influence the thermodynamics of soil layers close to freezing. We also present results from three experiments in which the standard model setup was modified to improve physical realism of the simulations in permafrost regions. Extending the soil column to a depth of 60 m and adjusting the soil parameters for organic content had relatively little effect on the simulation of permafrost and ALT. A higher vertical resolution improves the simulation of ALT, although a considerable bias still remains. Future model

  5. Simulation of permafrost and seasonal thaw depth in the JULES land surface scheme

    Directory of Open Access Journals (Sweden)

    R. Dankers

    2011-09-01

    Full Text Available Land surface models (LSMs need to be able to simulate realistically the dynamics of permafrost and frozen ground. In this paper we evaluate the performance of the LSM JULES (Joint UK Land Environment Simulator, the stand-alone version of the land surface scheme used in Hadley Centre climate models, in simulating the large-scale distribution of surface permafrost. In particular we look at how well the model is able to simulate the seasonal thaw depth or active layer thickness (ALT. We performed a number of experiments driven by observation-based climate datasets. Visually there is a very good agreement between areas with permafrost in JULES and known permafrost distribution in the Northern Hemisphere, and the model captures 97% of the area where the spatial coverage of the permafrost is at least 50%. However, the model overestimates the total extent as it also simulates permafrost where it occurs sporadically or only in isolated patches. Consistent with this we find a cold bias in the simulated soil temperatures, especially in winter. However, when compared with observations on end-of-season thaw depth from around the Arctic, the ALT in JULES is generally too deep. Additional runs at three sites in Alaska demonstrate how uncertainties in the precipitation input affect the simulation of soil temperatures by affecting the thickness of the snowpack and therefore the thermal insulation in winter. In addition, changes in soil moisture content influence the thermodynamics of soil layers close to freezing. We also present results from three experiments in which the standard model setup was modified to improve physical realism of the simulations in permafrost regions. Extending the soil column to a depth of 60 m and adjusting the soil parameters for organic content had relatively little effect on the simulation of permafrost and ALT. A higher vertical resolution improves the simulation of ALT, although a considerable bias still remains. Future model

  6. Growth kinetics of microorganisms isolated from Alaskan soil and permafrost in solid media frozen down to -35 degrees C.

    Science.gov (United States)

    Panikov, Nicolai S; Sizova, Maria V

    2007-02-01

    We developed a procedure to culture microorganisms below freezing point on solid media (cellulose powder or plastic film) with ethanol as the sole carbon source without using artificial antifreezes. Enrichment from soil and permafrost obtained on such frozen solid media contained mainly fungi, and further purification resulted in isolation of basidiomycetous yeasts of the genera Mrakia and Leucosporidium as well as ascomycetous fungi of the genus Geomyces. Contrary to solid frozen media, the enrichment of liquid nutrient solutions at 0 degrees C or supercooled solutions stabilized by glycerol at -1 to -5 degrees C led to the isolation of bacteria representing the genera Polaromonas, Pseudomonas and Arthrobacter. The growth of fungi on ethanol-microcrystalline cellulose media at -8 degrees C was exponential with generation times of 4.6-34 days, while bacteria displayed a linear or progressively declining curvilinear dynamic. At -17 to -0 degrees C the growth of isolates and entire soil community on 14C-ethanol was continuous and characterized by yields of 0.27-0.52 g cell C (g of C-substrate)(-1), similar to growth above the freezing point. The 'state of maintenance,' implying measurable catabolic activity of non-growing cells, was not confirmed. Below -18 to -35 degrees C, the isolated organisms were able to grow only transiently for 3 weeks after cooling with measurable respiratory and biosynthetic (14CO2 uptake) activity. Then metabolic activity declined to zero, and microorganisms entered a state of reversible dormancy.

  7. ESA DUE Permafrost: Evaluation of remote sensing derived products using ground data from the Global Terrestrial Network of Permafrost (GTN-P)

    Science.gov (United States)

    Elger, K. K.; Heim, B.; Lantuit, H.; Boike, J.; Bartsch, A.; Paulik, C.; Duguay, C. R.; Hachem, S.; Soliman, A. S.

    2011-12-01

    The task of the ESA DUE Permafrost project is to build up an Earth observation service for high-latitudinal permafrost applications with extensive involvement of the permafrost research community. The DUE Permafrost products derived from remote sensing are land surface temperature (LST), surface soil moisture (SSM), surface frozen and thawed state (freeze/ thaw), terrain, land cover, and surface waters. Weekly and monthly averages for most of the DUE Permafrost products will be made available for the years 2007-2010. The DUE Permafrost products are provided for the circumpolar permafrost area (north of 55°N) with 25 km spatial resolution. In addition, regional products with higher spatial resolution (300-1000 m/ pixel) were developed for five case study regions. These regions are: (1) the Laptev Sea and Eastern Siberian Sea Region (RU, continuous very cold permafrost/ tundra), (2) the Yakutsk Region (RU, continuous cold permafrost/ taiga), (3) the Western Siberian transect including Yamal Peninsula and Ob Region (RU, continuous to discontinuous/ taiga-tundra), (4) the Alaska Highway Transect (US, continuous to discontinuous/ taiga-tundra), and (5) the Mackenzie Delta and Valley Transect (CA, continuous to discontinuous/ taiga-tundra). The challenge of the programme is to adapt remote sensing products that are well established and tested in agricultural low and mid-latitudinal areas for highly heterogeneous taiga/ tundra permafrost landscapes in arctic regions. Ground data is essential for the evaluation of DUE Permafrost products and is provided by user groups and global networks. A major part of the DUE Permafrost core user group is contributing to GTN-P, the Global Terrestrial Network of Permafrost. Its main programmes, the Circumpolar Active Layer Monitoring (CALM) and the Thermal State of Permafrost (TSP) have been thoroughly overhauled during the last International Polar Year (2007-2008). Their spatial coverage has been extended to provide a true circumpolar

  8. Airborne electromagnetic imaging of discontinuous permafrost

    Science.gov (United States)

    Minsley, Burke J.; Abraham, Jared D.; Smith, Bruce D.; Cannia, James C.; Voss, Clifford I.; Jorgenson, M. Torre; Walvoord, Michelle A.; Wylie, Bruce K.; Anderson, Lesleigh; Ball, Lyndsay B.; Deszcz-Pan, Maryla; Wellman, Tristan P.; Ager, Thomas A.

    2012-01-01

    The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering ˜1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past ˜4 million years and the configuration of permafrost to depths of ˜100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the boundary between continuous permafrost to the north and discontinuous permafrost to the south, making it an important location for examining permafrost dynamics. Our results not only provide a detailed snapshot of the present-day configuration of permafrost, but they also expose previously unseen details about potential surface - groundwater connections and the thermal legacy of surface water features that has been recorded in the permafrost over the past ˜1,000 years. This work will be a critical baseline for future permafrost studies aimed at exploring the connections between hydrogeologic, climatic, and ecological processes, and has significant implications for the stewardship of Arctic environments.

  9. Impact processes, permafrost dynamics, and climate and environmental variability in the terrestrial Arctic as inferred from the unique 3.6 Myr record of Lake El'gygytgyn, Far East Russia - A review

    Science.gov (United States)

    Wennrich, Volker; Andreev, Andrei A.; Tarasov, Pavel E.; Fedorov, Grigory; Zhao, Wenwei; Gebhardt, Catalina A.; Meyer-Jacob, Carsten; Snyder, Jeffrey A.; Nowaczyk, Norbert R.; Schwamborn, Georg; Chapligin, Bernhard; Anderson, Patricia M.; Lozhkin, Anatoly V.; Minyuk, Pavel S.; Koeberl, Christian; Melles, Martin

    2016-09-01

    Lake El'gygytgyn in Far East Russia is a 3.6 Myr old impact crater lake. Located in an area that has never been affected by Cenozoic glaciations nor desiccation, the unique sediment record of the lake represents the longest continuous sediment archive of the terrestrial Arctic. The surrounding crater is the only impact structure on Earth developed in mostly acid volcanic rocks. Recent studies on the impactite, permafrost, and sediment sequences recovered within the framework of the ICDP "El'gygytgyn Drilling Project" and multiple pre-site surveys yielded new insight into the bedrock origin and cratering processes as well as permafrost dynamics and the climate and environmental history of the terrestrial Arctic back to the mid-Pliocene. Results from the impact rock section recovered during the deep drilling clearly confirm the impact genesis of the El'gygytgyn crater, but indicate an only very reduced fallback impactite sequence without larger coherent melt bodies. Isotope and element data of impact melt samples indicate a F-type asteroid of mixed composition or an ordinary chondrite as the likely impactor. The impact event caused a long-lasting hydrothermal activity in the crater that is assumed to have persisted for c. 300 kyr. Geochemical and microbial analyses of the permafrost core indicate a subaquatic formation of the lower part during lake-level highstand, but a subaerial genesis of the upper part after a lake-level drop after the Allerød. The isotope signal and ion compositions of ground ice is overprinted by several thaw-freeze cycles due to variations in the talik underneath the lake. Modeling results suggest a modern permafrost thickness in the crater of c. 340 m, and further confirm a pervasive character of the talik below Lake El'gygytgyn. The lake sediment sequences shed new leight into the Pliocene and Pleistocene climate and environmental evolution of the Arctic. During the mid-Pliocene, significantly warmer and wetter climatic conditions in

  10. Investigation of Soil and Vegetation Characteristics in Discontinuous Permafrost Landscapes Near Fairbanks, Alaska

    Science.gov (United States)

    2015-08-01

    1986. Methods of Soil Analysis: Part 1—Physical and Mineralogical Methods. 3rd ed. Madison, WI: Soil Science Society of America Press. Lichvar...Madison, WI: Soil Science Society of America , Inc. IBM Corp. 2011. IBM SPSS for Windows, Version 20.0. Armonk, NY: IBM Corp. Stow, D. A., A. Hope... Science Society of America Journal 53 (3): 883– 890. Fisher, J. P., C. Estop-Aragones, G. Xenakis, I. P. Hartley, J. Murton, D. Charman, and G. K

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

    Directory of Open Access Journals (Sweden)

    E. E. Jafarov

    2012-01-01

    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. Input parameters to the model are spatial datasets of mean monthly air temperature and precipitation, prescribed thermal properties of the multilayered soil column, and water content which 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 preliminary modeling results based on input of 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 CALM active layer monitoring stations. Calibrated model was used to address possible ground temperature changes for the 21st century. The model simulation results show the widespread permafrost degradation in Alaska could begin in 2040–2099 time frame within the vast area southward from the Brooks Range except for the high altitudes of the Alaska Range and Wrangell Mountains.

  12. 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.

  13. Western Arctic Coastal Plain, IfSAR DSM-derived coastline and coastal features. University of Alaska Fairbanks, Geophysical Institute Permafrost Laboratory (2012).

    Data.gov (United States)

    Arctic Landscape Conservation Cooperative — This dataset consists of a polyline depicting the coast and coastal features of the western Arctic Coastal Plain as derived from a mosaic created from an...

  14. Sphingomonas qilianensis sp. nov., Isolated from Surface Soil in the Permafrost Region of Qilian Mountains, China.

    Science.gov (United States)

    Piao, Ai-Lian; Feng, Xiao-Min; Nogi, Yuichi; Han, Lu; Li, Yonghong; Lv, Jie

    2016-04-01

    A Gram-stain-negative, strictly aerobic, non-motile and rod-shaped bacterial strain, designated X1(T), was isolated from the permafrost region of Qilian Mountains in northwest of China. Phylogenetic analyses of 16S rRNA gene sequence revealed that strain X1(T) was a member of the genus Sphingomonas and shared the highest 16S rRNA gene sequence similarity with Sphingomonas oligophenolica JCM 12082(T) (96.9%), followed by Sphingomonas glacialis CGMCC 1.8957(T) (96.7%) and Sphingomonas alpina DSM 22537(T) (96.4%). Strain X1(T) was able to grow at 15-30 °C, pH 6.0-10.0 and with 0-0.3% NaCl (w/v). The DNA G+C content of the isolate was 64.8 mol%. Strain X1(T)-contained Q-10 as the dominant ubiquinone and C(18:1)ω7c, C(16:1)ω7c, C(16:0) and C(14:0) 2-OH as the dominant fatty acids. The polar lipid profile of strain XI(T)-contained sphingoglycolipid, phosphatidylglycerol, phosphatidylethanolamine, one unidentified glycolipid and two unidentified phospholipid. Due to the phenotypic and genetic distinctiveness and other characteristic studied in this article, we consider X1(T) as a novel species of the genus Sphingomonas and propose to name it Sphingomonas qilianensis sp. nov. The type strain is X1(T) (=CGMCC 1.15349(T) = KCTC 42862(T)).

  15. Soil Temperature Station Data from Permafrost Regions of Russia (Selection of Five Stations), 1880s - 2000

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set includes soil temperature data from boreholes located at five stations in Russia: Yakutsk, Verkhoyansk, Pokrovsk, Isit', and Churapcha. The data have...

  16. Herbivore impact on moss depth, soil temperature and arctic plant growth

    NARCIS (Netherlands)

    van der Wal, R; Loonen, MJJE

    2001-01-01

    We provide evidence for a mechanism by which herbivores may influence plant abundance in arctic ecosystems, These systems are commonly dominated by mosses, the thickness of which influences the amount of heat reaching the soil surface. Herbivores can reduce the thickness of the moss layer by means o

  17. Survival of rapidly fluctuating natural low winter temperatures by High Arctic soil invertebrates

    DEFF Research Database (Denmark)

    Convey, Peter; Abbandonato, Holly; Bergan, Frode;

    2015-01-01

    experienced at microhabitat level, few studies have explicitly set out to link field conditions experienced by natural multispecies communities with the more detailed laboratory ecophysiological studies of a small number of 'representative' species. This is particularly the case during winter, when snow cover...... microhabitats. To assess survival of natural High Arctic soil invertebrate communities contained in soil and vegetation cores to natural winter temperature variations, the overwintering temperatures they experienced were manipulated by deploying cores in locations with varying snow accumulation: No Snow...

  18. The role of organic soil layer on the fate of Siberian larch forest and near-surface permafrost under changing climate: A simulation study

    Science.gov (United States)

    SATO, H.; Iwahana, G.; Ohta, T.

    2013-12-01

    Siberian larch forest is the largest coniferous forest region in the world. In this vast region, larch often forms nearly pure stands, regenerated by recurrent fire. This region is characterized by a short and dry growing season; the annual mean precipitation for Yakutsk was only about 240 mm. To maintain forest ecosystem under such small precipitation, underlying permafrost and seasonal soil freezing-thawing-cycle have been supposed to play important roles; (1) frozen ground inhibits percolation of soil water into deep soil layers, and (2) excess soil water at the end of growing season can be carried over until the next growing season as ice, and larch trees can use the melt water. As a proof for this explanation, geographical distribution of Siberian larch region highly coincides with continuous and discontinuous permafrost zone. Recent observations and simulation studies suggests that existences of larch forest and permafrost in subsurface layer are co-dependent; permafrost maintains the larch forest by enhancing water use efficiency of trees, while larch forest maintains permafrost by inhibiting solar radiation and preventing heat exchanges between soil and atmosphere. Owing to such complexity and absence of enough ecosystem data available, current-generation Earth System Models significantly diverse in their prediction of structure and key ecosystem functions in Siberian larch forest under changing climate. Such uncertainty should in turn expand uncertainty over predictions of climate, because Siberian larch forest should have major role in the global carbon balance with its huge area and vast potential carbon pool within the biomass and soil, and changes in boreal forest albedo can have a considerable effect on Northern Hemisphere climate. In this study, we developed an integrated ecosystem model, which treats interactions between plant-dynamics and freeze-thaw cycles. This integrated model contains a dynamic global vegetation model SEIB-DGVM, which simulates

  19. Permafrost thawing and increased winter discharge in Northern Norway - is there a connection?

    Science.gov (United States)

    Westermann, S.; Etzelmuller, B.

    2013-12-01

    Trends of increasing winter river discharge have been observed in many areas in the Arctic. Spatially distributed modeling of the ground thermal regime in conjunction with multi-decadal time series of discharge measurements provides the opportunity to investigate the role of permafrost thaw as contributing factor to such changes. In Northern Norway, there exist a number of gauged watersheds in permafrost regions for which 30- to 100-year records of discharge measurements are available. Numerical simulations of the evolution of the ground temperature regime have been performed at 1km resolution with the transient permafrost model CryoGrid 2 (Westermann et el. 2013) for the last 50 years for an area of approximately 55,000km2. As an example, we present the Iesjohka watershed, located at 69.5°N with a size of approximately 2000 km2. It extends across the boundary between permafrost-free coastal regions and more continental plains dominated by discontinuous permafrost, and features a variety of landcover types including organic-rich palsa mires. During summer, the Iesjohka has an average discharge of 20 to 50 m3/s, while the typical winter discharge is on the order of a few m3/s. Since the beginning of measurements in 1974, the average discharge in the winter months November to February and the annual minimum discharge have more than doubled, while CryoGrid 2 simulations show that permafrost has crossed the thawing threshold in a large part of the watershed between 1980 and 2010. In 2013, degradation of palsas and collapses of peat plateaus have been observed at many places along a 50 km transect through the watershed, transforming comparatively dry areas underlain by permafrost in permafrost-free water-saturated mires. Similar increases of the winter discharge have been observed for other permafrost watersheds in Northern Norway, thus suggesting a causal relationship between permafrost thaw and increased winter discharge. To further investigate this hypothesis, we

  20. The Frozen Ground Data Center: New Data for the International Permafrost Community

    Science.gov (United States)

    Parsons, M. A.; Zhang, T.

    2002-12-01

    Permafrost and seasonally frozen ground regions occupy about 24 percent and 60 percent, respectively, of the exposed land surface in the Northern Hemisphere. Data and information on frozen ground collected over many decades and in the future are critical for fundamental process understanding, environmental change detection and impact assessment, model validation, and engineering application in seasonal frost and permafrost regions. However, many of these data sets and information remain widely dispersed and relatively unavailable to the national and international science and engineering community, and some are in danger of being lost permanently. The International Permafrost Association (IPA) has long recognized the inherent and lasting value of data and information and has worked to prioritize and assess permafrost data requirements and to identify critical data sets for scientific and engineering purposes. At the Seventh International Conference on Permafrost in 1998 in Yellowknife, Canada, the first Circumpolar Active-Layer Permafrost System (CAPS) CD-ROM was published and delivered to the Conference delegates. To continue the IPA strategy for data and information management and to meet the requirements by cold regions science, engineering, and modeling community, the World Data Center (WDC) for Glaciology, Boulder in collaboration with the International Arctic Research Center (IARC) has initiated a new Frozen Ground Data Center (FGDC) as a key node in the IPA's Global Geocryological Data (GGD) system. The FGDC has expanded access to the 1998 CAPS data, is expanding data holdings, and is creating a new version of the CD to be distributed at the July 2003 IPA conference in Zurich. The FGDC has improved access to existing data through an online search and order system and availability in the Global Change Master Directory. The FGDC has also expanded and updated current holdings with global and regional permafrost, soil temperature, and soil classification maps in

  1. Biogeochemistry: Long-term effects of permafrost thaw

    Science.gov (United States)

    Zona, Donatella

    2016-09-01

    Carbon emissions from the Arctic tundra could increase drastically as global warming thaws permafrost. Clues now obtained about the long-term effects of such thawing on carbon dioxide emissions highlight the need for more data.

  2. The new database of the Global Terrestrial Network for Permafrost (GTN-P)

    Science.gov (United States)

    Biskaborn, B. K.; Lanckman, J.-P.; Lantuit, H.; Elger, K.; Streletskiy, D. A.; Cable, W. L.; Romanovsky, V. E.

    2015-09-01

    The Global Terrestrial Network for Permafrost (GTN-P) provides the first dynamic database associated with the Thermal State of Permafrost (TSP) and the Circumpolar Active Layer Monitoring (CALM) programs, which extensively collect permafrost temperature and active layer thickness (ALT) data from Arctic, Antarctic and mountain permafrost regions. The purpose of GTN-P is to establish an early warning system for the consequences of climate change in permafrost regions and to provide standardized thermal permafrost data to global models. In this paper we introduce the GTN-P database and perform statistical analysis of the GTN-P metadata to identify and quantify the spatial gaps in the site distribution in relation to climate-effective environmental parameters. We describe the concept and structure of the data management system in regard to user operability, data transfer and data policy. We outline data sources and data processing including quality control strategies based on national correspondents. Assessment of the metadata and data quality reveals 63 % metadata completeness at active layer sites and 50 % metadata completeness for boreholes. Voronoi tessellation analysis on the spatial sample distribution of boreholes and active layer measurement sites quantifies the distribution inhomogeneity and provides a potential method to locate additional permafrost research sites by improving the representativeness of thermal monitoring across areas underlain by permafrost. The depth distribution of the boreholes reveals that 73 % are shallower than 25 m and 27 % are deeper, reaching a maximum of 1 km depth. Comparison of the GTN-P site distribution with permafrost zones, soil organic carbon contents and vegetation types exhibits different local to regional monitoring situations, which are illustrated with maps. Preferential slope orientation at the sites most likely causes a bias in the temperature monitoring and should be taken into account when using the data for global

  3. Permafrost monitoring K12 outreach program

    Science.gov (United States)

    Yoshikawa, K.; Saito, T.; Romanovsky, V.

    2007-12-01

    The objective of this project is to establish long-term permafrost monitoring sites adjacent to schools along the circum polar permafrost region. Permafrost will be one of the important indicators for monitoring climatic change in the future. Change in permafrost conditions also affects local ecosystems, hydrological regimes and natural disasters. The purpose of the long-term permafrost observation is fitting for future science objectives, and can also benefit students and teachers in remote village schools. Most remote villages depend on a subsistence lifestyle and will be directly affected by changing climate and permafrost condition. Monitoring the permafrost temperature in the arctic for a better understanding of the spatial distribution of permafrost and having students participate to collect the data is an ideal IPY project. Our outreach project involves drilling boreholes at village schools and installing the micro data logger with temperature sensors to measure hourly air and permafrost temperatures. Trained teachers help students download data several times a year and discuss the results in class. The data gathered from these stations is shared and can be viewed by anyone through the Internet (http://www.uaf.edu/permafrost). Using the Internet teachers can also compare their data with data form other monitoring stations. This project is becoming an useful science project for these remote villages, which tends to have limited exposure to science, despite the changing surroundings that they're daily lives depend on. NSF (EPSCoR) funded the previous seeding outreach program. Currently NSF/NASA and the International Polar Year (IPY) program support this project. In the 2006 field season, thirty-one schools participated in installing the monitoring stations. In 2007 we propose the expansion of this project to involve an additional 100 villages along the arctic. The broader impacts of this project are 1). This project will provide opportunities for field

  4. Bacterial community composition and diversity of five different permafrost-affected soils of Northeast Greenland.

    Science.gov (United States)

    Ganzert, Lars; Bajerski, Felizitas; Wagner, Dirk

    2014-08-01

    Greenland is one of the regions of interest with respect to climate change and global warming in the Northern Hemisphere. Little is known about the structure and diversity of the terrestrial bacterial communities in ice-free areas in northern Greenland. These soils are generally poorly developed and usually carbon- and nitrogen-limited. Our goal was to provide the first insights into the soil bacterial communities from five different sites in Northeast Greenland using culture-independent and culture-dependent methods. The comparison of environmental and biological data showed that the soil bacterial communities are diverse and significantly pH-dependent. The most frequently detected OTUs belonged to the phyla Acidobacteria, Bacteroidetes and (Alpha-, Beta-, Delta-) Proteobacteria. Low pH together with higher nitrogen and carbon concentrations seemed to support the occurrence of (Alpha-, Beta-, Delta-) Proteobacteria (at the expense of Acidobacteria), whereas Bacteroidetes were predominant at higher values of soil pH. Our study indicates that pH is the main factor for shaping bacterial community, but carbon and nitrogen concentrations as well may become important, especially for selecting oligotrophic microorganisms.

  5. Crude oil treatment leads to shift of bacterial communities in soils from the deep active layer and upper permafrost along the China-Russia Crude Oil Pipeline route.

    Science.gov (United States)

    Yang, Sizhong; Wen, Xi; Zhao, Liang; Shi, Yulan; Jin, Huijun

    2014-01-01

    The buried China-Russia Crude Oil Pipeline (CRCOP) across the permafrost-associated cold ecosystem in northeastern China carries a risk of contamination to the deep active layers and upper permafrost in case of accidental rupture of the embedded pipeline or migration of oil spills. As many soil microbes are capable of degrading petroleum, knowledge about the intrinsic degraders and the microbial dynamics in the deep subsurface could extend our understanding of the application of in-situ bioremediation. In this study, an experiment was conducted to investigate the bacterial communities in response to simulated contamination to deep soil samples by using 454 pyrosequencing amplicons. The result showed that bacterial diversity was reduced after 8-weeks contamination. A shift in bacterial community composition was apparent in crude oil-amended soils with Proteobacteria (esp. α-subdivision) being the dominant phylum, together with Actinobacteria and Firmicutes. The contamination led to enrichment of indigenous bacterial taxa like Novosphingobium, Sphingobium, Caulobacter, Phenylobacterium, Alicylobacillus and Arthrobacter, which are generally capable of degrading polycyclic aromatic hydrocarbons (PAHs). The community shift highlighted the resilience of PAH degraders and their potential for in-situ degradation of crude oil under favorable conditions in the deep soils.

  6. Crude oil treatment leads to shift of bacterial communities in soils from the deep active layer and upper permafrost along the China-Russia Crude Oil Pipeline route.

    Directory of Open Access Journals (Sweden)

    Sizhong Yang

    Full Text Available The buried China-Russia Crude Oil Pipeline (CRCOP across the permafrost-associated cold ecosystem in northeastern China carries a risk of contamination to the deep active layers and upper permafrost in case of accidental rupture of the embedded pipeline or migration of oil spills. As many soil microbes are capable of degrading petroleum, knowledge about the intrinsic degraders and the microbial dynamics in the deep subsurface could extend our understanding of the application of in-situ bioremediation. In this study, an experiment was conducted to investigate the bacterial communities in response to simulated contamination to deep soil samples by using 454 pyrosequencing amplicons. The result showed that bacterial diversity was reduced after 8-weeks contamination. A shift in bacterial community composition was apparent in crude oil-amended soils with Proteobacteria (esp. α-subdivision being the dominant phylum, together with Actinobacteria and Firmicutes. The contamination led to enrichment of indigenous bacterial taxa like Novosphingobium, Sphingobium, Caulobacter, Phenylobacterium, Alicylobacillus and Arthrobacter, which are generally capable of degrading polycyclic aromatic hydrocarbons (PAHs. The community shift highlighted the resilience of PAH degraders and their potential for in-situ degradation of crude oil under favorable conditions in the deep soils.

  7. Trace element fractionation and transport in boreal rivers and soil porewaters of permafrost-dominated basaltic terrain in Central Siberia

    Science.gov (United States)

    Pokrovsky, O. S.; Schott, J.; Dupré, B.

    2006-07-01

    The chemical status of ˜40 major and trace elements (TE) and organic carbon (OC) in pristine boreal rivers draining the basaltic plateau of Central Siberia (Putorana) and interstitial solutions of permafrost soils was investigated. Water samples were filtered in the field through progressively decreasing pore size (5 μm → 0.22 μm → 0.025 μm → 10 kDa → 1 kDa) using cascade frontal filtration technique. Most rivers and soil porewaters exhibit 2-5 times higher than the world average concentration of dissolved (i.e., Ultrafiltration revealed strong relationships between concentration of TE and that of colloidal Fe and Al. According to their partition during filtration and association with colloids, two groups of elements can be distinguished: (i) those weakly dependent on ultrafiltration and that are likely to be present as truly dissolved inorganic species (Li, Na, K, Si, Mn, Mo, Rb, Cs, As, Sb) or, partially (20-30%) associated with small size Fe- and Al-colloids (Ca, Mg, Sr, Ba) and to small (complexes (Co, Ni, Cu, Zn), and (ii) elements strongly associated with colloidal iron and aluminum in all ultrafiltrates largely present in 1-100 kDa fraction (Ga, Y, REEs, Pb, V, Cr, Ti, Ge, Zr, Th, U). TE concentrations and partition coefficients did not show any detectable variations between different colloidal fractions for soil porewaters, suprapermafrost flow and surface streams. TE concentration measurements in river suspended particles demonstrated significant contribution (i.e., ⩾30%) of conventionally dissolved (<0.22 μm) forms for usually "immobile" elements such as divalent transition metals, Cd, Pb, V, Sn, Y, REEs, Zr, Hf, Th. The Al-normalized accumulation coefficients of TE in vegetation litter compared to basalts achieve 10-100 for B, Mn, Zn, As, Sr, Sn, Sb, and the larch litter degradation is able to provide the major contribution to the annual dissolved flux of most trace elements. It is hypothesized that the decomposition of plant litter in the

  8. Fate of permafrost-released organic matter in the Laptev Sea: What is its lateral transport time along the transect from the Lena delta area to the deep sea of the Arctic interior?

    Science.gov (United States)

    Bröder, L.; Tesi, T.; Bruchert, V.; Dudarev, O.; Semiletov, I. P.; Gustafsson, O.

    2015-12-01

    Ongoing global warming may cause an increasing supply of permafrost-derived organic carbon through both river discharge and coastal erosion to the Arctic shelves where it can be either degraded to CO2 and outgassed, buried in sediments or transported to the deep sea. Here we assess the balance between burial and lateral transport on the fate of terrestrial organic carbon (TerrOC) by exploring how it changes in concentration, composition and degradation status during both cross-shelf transport and burial. We analyzed a suite of terrestrial biomarkers as well as source-diagnostic bulk carbon isotopes (δ13C, Δ14C) in sediments from the wide Siberian Arctic Shelf and found contrasting trends for the operationally-defined carbon pools. TerrOC concentrations and degradation status vary noticeably more during cross-shelf transport than after burial. The concentrations of lignin phenols, cutin acids and high-molecular weight (HMW) wax lipids (tracers of vascular plants) do not display clear changes over time during sediment accumulation, while they significantly decrease along the transect. Molecular-based degradation proxies for TerrOC (e.g., CPI of HMW lipids, the HMW acids/alkanes ratio and the acid/aldehyde ratio of lignin phenols) do not suggest extensive down-core mineralization, but there appears to be a trend to more degraded TerrOC with increasing distance from the coast. We infer that the degree of degradation of permafrost-derived TerrOC is a function of the time spent under oxic conditions (oxygen exposure time, OET). Specifically, one possible explanation for these patterns could be protracted OETs during cross-shelf transport compared to rather short in situ OETs after burial. To test this hypothesis we estimate lateral transport times using compound-specific radiocarbon analysis for terrestrial OC biomarkers (HMW fatty acids) and compare these with in situ OETs calculated from measured oxygen penetration depths and 210Pb-derived sedimentation rates.

  9. Nitrous oxide production and emission in high arctic soils of NW Greenland

    Science.gov (United States)

    Stills, A.; Lupascu, M.; Czimczik, C. I.; Sharp, E. D.; Welker, J. M.; Schaeffer, S. M.

    2010-12-01

    Nitrous oxide (N2O) is a potent ozone depleting greenhouse gas with a global warming potential 298 times larger than carbon dioxide (CO2 on a 100-year time scale. Recent studies identified arctic soils undergoing thawing and changes in drainage as potentially large sources of N2O to the atmosphere. More in situ2O production in and emission from arctic soils are needed to understand ecosystem feedbacks to climate change in high arctic tundra, and the role of high latitudes in the global N2O budget. We monitored the concentration of N2O in soils and emissions of N2O to the atmosphere from prostrate shrub tundra in NW Greenland under current and future climate conditions. Measurements were made monthly from June to August 2010 at a long-term climate change experiment started in 2003 consisting of +2oC warming (T1), +4oC warming (T2), +50% summer precipitation (W), +4oC × +50% summer precipitation (T2W), and control (C). In each treatment, N2O was monitored from vegetated and barren soils. In addition, we quantified nitrogen (N) mineralization rates. The concentration of N2O in soils was measured by sampling air from permanent wells ranging from 20 to 90 cm soil depth. N2O emissions were measured every 15 minutes for one hour using opaque, static chambers. Nitrous oxide samples were collected manually with syringes and stored in pre-evacuated glass vials with butyl rubber septa and aluminum crimp. The vials were sealed with silicon, shipped to UC Irvine, and analyzed by GC-ECD (Shimadzu GC-2014). To determine soil N mineralization rates, resin bags were installed under PVC cores from 8 to 10 cm in early spring in all treatments. Bags were removed at peak season. A second set was installed to capture end-of-season mineralization rates. Resin bags were extracted for future analysis of total accumulated ammonium and nitrate. Soil cores concurrently collected with resin bag installation and removal will be analyzed for % C and N, and were extracted for future analysis of

  10. Rapid Arctic Changes due to Infrastructure and Climate (RATIC) in the Russian North

    Science.gov (United States)

    Walker, D. A.; Kofinas, G.; Raynolds, M. K.; Kanevskiy, M. Z.; Shur, Y.; Ambrosius, K.; Matyshak, G. V.; Romanovsky, V. E.; Kumpula, T.; Forbes, B. C.; Khukmotov, A.; Leibman, M. O.; Khitun, O.; Lemay, M.; Allard, M.; Lamoureux, S. F.; Bell, T.; Forbes, D. L.; Vincent, W. F.; Kuznetsova, E.; Streletskiy, D. A.; Shiklomanov, N. I.; Fondahl, G.; Petrov, A.; Roy, L. P.; Schweitzer, P.; Buchhorn, M.

    2015-12-01

    The Rapid Arctic Transitions due to Infrastructure and Climate (RATIC) initiative is a forum developed by the International Arctic Science Committee (IASC) Terrestrial, Cryosphere, and Social & Human working groups for developing and sharing new ideas and methods to facilitate the best practices for assessing, responding to, and adaptively managing the cumulative effects of Arctic infrastructure and climate change. An IASC white paper summarizes the activities of two RATIC workshops at the Arctic Change 2014 Conference in Ottawa, Canada and the 2015 Third International Conference on Arctic Research Planning (ICARP III) meeting in Toyama, Japan (Walker & Pierce, ed. 2015). Here we present an overview of the recommendations from several key papers and posters presented at these conferences with a focus on oil and gas infrastructure in the Russian north and comparison with oil development infrastructure in Alaska. These analyses include: (1) the effects of gas- and oilfield activities on the landscapes and the Nenets indigenous reindeer herders of the Yamal Peninsula, Russia; (2) a study of urban infrastructure in the vicinity of Norilsk, Russia, (3) an analysis of the effects of pipeline-related soil warming on trace-gas fluxes in the vicinity of Nadym, Russia, (4) two Canadian initiatives that address multiple aspects of Arctic infrastructure called Arctic Development and Adaptation to Permafrost in Transition (ADAPT) and the ArcticNet Integrated Regional Impact Studies (IRIS), and (5) the effects of oilfield infrastructure on landscapes and permafrost in the Prudhoe Bay region, Alaska.

  11. Thermal erosion of ice-wedge polygon terrains changes fluxes of energy and matter of permafrost geosystems

    Science.gov (United States)

    Fortier, D.; Godin, E.; Lévesque, E.; Veillette, A.; Lamarque, L.

    2015-12-01

    Subsurface thermal erosion is triggered by convective heat transfers between flowing water and permafrost. Heat advection due to infiltration of run-off in the massive ice wedges and the ice-rich upper portion of permafrost creates sink holes and networks of interconnected tunnels in the permafrost. Mass movements such as collapse of tunnel's roof, retrogressive thaw-slumping and active layer detachment slides lead to the development of extensive gully networks in the landscape. These gullies drastically change the hydrology of ice-wedge polygon terrains and the fluxes of heat, water, sediment, nutrients and carbon within the geosystem. Exportation of sediments out of gullies are positive mechanical feed-back that keep channels active for decades. Along gully margins, drainage of disturbed polygons and ponds, slope drainage, soil consolidation, gully walls colonization by vegetation and wet to mesic plant succession change the thermal properties of the active layer and create negative feedback effects that stabilize active erosion processes and promote permafrost recovery in gully slopes and adjacent disturbed polygons. On Bylot Island (Nunavut), over 40 gullies were monitored to characterize gully geomorphology, thermal and mechanical processes of gully erosion, rates of gully erosion over time within different sedimentary deposits, total volume of eroded permafrost at the landscape scale and gully hydrology. We conducted field and laboratory experiments to quantify heat convection processes and speed of ice wedge ablation in order to derive empirical equations to develop model of permafrost thermal erosion. We used data, collected over 10 years, of geomorphological gully monitoring and regional climate scenarios to evaluate the potential response of ice-wedge polygon terrains to changes in snow, permafrost thermal regime and hydrological conditions over the coming decades and its implication for the short and long term dynamics of arctic permafrost geosystems.

  12. Role of mineralogy and particle-size distribution on patterned ground genesis in no-permafrost soils. Majella massif (Italy) and English Lake District (United Kingdom)

    Science.gov (United States)

    Cioci, C.; Basili, M.; Cocco, S.; Agnelli, A.; Warburton, J.; Corti, G.

    2009-04-01

    Patterned ground soils form by self-organization thanks to soil heaving caused by seasonal variation of ice table, but also in no-permafrost affected soils thanks to diurnal or seasonal freeze/thaw cycles. The genesis of the superficial soil pattern is thought to be due to cryo-selection of the skeletal particles, which is induced by freezing/thawing cycles of the water present in the saturated active soil layer. Other conditions required for the formation of a patterned ground are: moderate to null slope, scarce vegetation and the presence of a sufficient amount of fine materials (fines). If all this attains, the stones are easily pushed out the freezing area, so producing sorted features where skeleton and fines are rather segregated. Patterned ground soils were described in a wide range of no-permafrost affected environments. Here, we report on the role of soil mineralogy and particle-size distribution in the genesis of patterned ground in two sites where permafrost is some meters deep (Majella massif, Central Italy) or absent (English Lake District, North West England). Majella massif (Monte Amaro, 2793 m a.s.l.) is at 42° North of latitude and is mainly composed by limestone, while English Lake District (Scafell Pike, 978 m a.s.l.) is at 54° North of latitude and is mainly composed by laminated mudstone and siltstone. Patterned ground soils described on the Majella massif are smaller than those at English Lake: the sorted circles of Majella massif have a diameter of about 5-7 cm while those of the English Lake have a diameter of about 15-20 cm. In each site several soil profiles were dug till about 1 m of depth, described and sampled according to the recognized horizons. All the soils are well drained thanks to high skeleton content (60 to 80%), which is also responsible of preventing soil saturation. The results of mineralogical and particles-size analysis show that the formation of a saturated active layer is possible thanks to the formation of an

  13. Erodibility of permafrost exposures in the coasts of Eastern Chukotka

    Science.gov (United States)

    Maslakov, Alexey; Kraev, Gleb

    2016-09-01

    Coastal retreat caused by coastal erosion decreases the territory of Russia by 50 km2 annually. Erosion of the Arctic coasts composed by fine-grained permafrost turns coastlines into badlands dozens of meters wide and is harmful to the coastal infrastructure. Regional-level variations in the coastal retreat rate in the Arctic tend to follow the climate change dynamics and its consequences, mainly the shrinkage of the perennial sea ice area. This study considers the lower level local-scale variability linked to permafrost features, lithology, and morphology of the coasts in the remote region on the western shore of the Bering Sea within Lorino settlement (Chukotka, Russia). The coastal dynamics was tracked by means of geodesy and remote sensing in 2012-14, and the archival engineering survey data available since 1967. We have derived the erodibility of sediments from the conventional soil properties measured by engineers, and linked the coastal retreat rates to erodibility of the sediments, so that it could be extrapolated to other coastal areas of Eastern Chukotka with similar sediment structure.

  14. Development of bearing capacity of fine grained permafrost deposits in western greenland urban areas subject to soil temperature changes

    DEFF Research Database (Denmark)

    Agergaard, Frederik Ancker; Ingeman-Nielsen, Thomas

    2012-01-01

    by 2-3 °C during the 21st century. This paper presents a relation between undrained shear strength and temperature based on a series triaxial tests of fine-grained permafrost in the interval from -3 °C to -1 °C. Moderately ice-rich permafrost and excess ice free refrozen active-layer were retrieved...... with increasing temperature. Both excess ice free and moderately ice-rich samples show a strength decrease of 21 %/°C from -3 °C to -1 °C. Other authors’ data suggest the same trend for moderately ice-rich samples, whereas it is suggested that further studies are conducted to validate the trend for excess ice....... The established trends could provide a valuable tool for foundation design in fine-grained permafrost areas....

  15. Permafrost and climate in Europe: monitoring and modelling thermal, geomorphological and geotechnical responses

    OpenAIRE

    2009-01-01

    We present a review of the changing state of European permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of Svalbard and the discontinuous high altitude mountain permafrost of Iceland, Fennoscandia and the Alps. The paper focuses on methodological developments and data collection over the last decade or so, including research associated with the continent-scale network of instrumented permafrost boreholes established between 1998 and 2001 under the E...

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

    Science.gov (United States)

    Swindles, Graeme T.; Morris, Paul J.

    2016-04-01

    High-latitude permafrost peatlands contain globally important amounts of soil organic carbon, owing to cold conditions which suppress anaerobic decomposition. However, there is much concern that climate warming and subsequent 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. Unfortunately, field monitoring campaigns only span the last few decades and therefore provide an incomplete picture of permafrost peatland response to rapid warming in the twentieth century. Here we use a high-resolution palaeoecological approach to understand the longer-term response of peatlands in Subarctic Sweden 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 in response to climatic warming, culminating in collapse of the peat domes. Commonalities between study sites lead us to propose a five-phase model for permafrost peatland response to climatic warming. This model suggests a shared ecohydrological trajectory towards a common end point: inundated Arctic fen. Although carbon accumulation is rapid in such sites, and thus peatland ecosystem services are resumed, saturated soil conditions are likely to cause elevated methane emissions that have implications for climate-feedback mechanisms. We outline our plans to test the model published in Swindles et al. (2015) using the same methodological approach in other high-latitude locations, including zones of continuous and discontinuous permafrost. Reference: Swindles, G.T., Morris, P.J., Mullan, D., Watson, E.J., Turner, T.E., Roland, T., Amesbury, M.J., Kokfelt, U., Schoning, K., Pratte, S., Gallego-Sala, A., Charman, D.J., Sanderson, N., Garneau, M., Carrivick, J.L., Woulds, C

  17. A Two-dimensional Heat Transfer Model for Atmosphere-land System in the Lake-dominated Alaskan Arctic

    Institute of Scientific and Technical Information of China (English)

    LING Feng; ZHANG Ting-jun

    2002-01-01

    Understanding lake ice growth and its sensitivity to climate change is vital to understand the thermal regime of thaw lake systems and predict their response to climate change. In this paper, a physically-based, two-dimensional, non-steady mathematical model is developed for studying the role of shallow tundra lakes in the Alaskan Arctic. Both the radiation absorption in lake water and the phasechange in permafrost are considerd in the model. The materials the model includes are snow, ice, water, unfrozen and frozen soil (peat, silt,sand and gravel). The basic inputs to the model observed mean daily air temperature and snow depth. The ability of this model to simulate lake ice growth and thickness variation, lake water temperature distribution, the thermal regime of permafrost and talik dynamics beneath lakes, and thawing rate of permafrost below and adjacent to shallow thaw lakes offers the potential to describe the effects of climate change in the Alaskan Arctic.

  18. The Frozen Ground Data Center: A Continuing Task for the International Permafrost Community

    Science.gov (United States)

    Parsons, M. A.; Zhang, T.; Barry, R. G.; Brown, J.

    2001-12-01

    Permafrost and seasonally frozen ground underlie about 24% and 60% of the surface of the Northern Hemisphere respectively. Data and information on frozen ground collected over many decades and in the future are critical for fundamental process understanding, environmental change detection, impact assessment, model validation, and engineering applications. However, many of these data sets and information remain widely dispersed and relatively unavailable to the science and engineering community, and some are in danger of being lost permanently. The International Permafrost Association (IPA) has long recognized the inherent and lasting value of data and information, and has developed a strategy for data and information management to meet the requirements of the cold regions science, engineering, and modeling community. NSIDC has played an active role in implementing this strategy by developing and distributing the first Circumpolar Active-Layer Permafrost System (CAPS) CD-ROM including the Global Geocryological Database (GGD). Now, NSIDC, in collaboration with the International Arctic Research Center (IARC), seeks to expand the CAPS data holdings, update the GGD, and improve frozen ground data access and utility through a new web-based "Frozen Ground Data Center." NSIDC plans to reformat several existing data sets and create value-added products such as gridded fields for model validation and analysis. We also plan to acquire and distribute certain key data sets, including data from: (1) the Global Terrestrial Network for Permafrost (GTN-P) and its Borehole and updated Circumpolar Active Layer Monitoring (CALM) components (Burgess et al 2000), (2) the Arctic Coastal Dynamics project, (3) the Cryosol database and maps, and (4) various permafrost maps and soil temperature time series for Russia and China. NSIDC seeks the help of the frozen ground research community through data contributions and suggestions on data acquisition, management and distribution. The IPA

  19. Methane emission from sub-sea permafrost in the East Siberian Arctic shelf: model-based evaluation of potential impact on global climate

    Science.gov (United States)

    Anisimov, O. A.; Lavrov, S. A.; Borzenkova, I. I.

    2011-12-01

    Several recent publications suggest that the observed high concentration of methane over the East Siberian Shelf (ESS) may be attributed to thawing and increased gas permeability (through taliks) of the sub-sea permafrost. Methane is released from unstable gas hydrates and propagates through newly formed taliks in the bottom sediments to the water and further to the atmosphere. Under sustained warming in the following decades it may have potentially dramatic effect on global climate. In this study we examine this hypothesis using comprehensive modelling approach. Direct observations indicate that since the mid-1980s bottom waters over the ESS warmed by ca. 2.1°C. We used the model to examine whether such changes may have caused substantial degradation of methane bearing sub-sea permafrost and CH4 supersaturation of the ESS sea waters. The model is based on the heat transfer equation and explicitly accounts for the effect of salt diffusion in the bottom sediments by coupling the thermal and mass fluxes. We forced the model by the prescribed seasonal bottom water temperature and salinity to calculate changes in the thermal state of permafrost after the inundation of the ESS, and to predict the changes in the following 1000 years. We used a climate scenario suggesting that at the time of inundation (ca 8 Ky BP) the top sediment layer warmed by ca. 12 °C from -13.5 °C (mean annual air temperature) to -1.5 °C (bottom water temperature). Afterwards temperature remained unchanged until 1985. Since then in accord with modern observations we imposed 0.09°C/year trend until 2100, and prescribed temperature to constant value of 11.5 °C afterwards. The rate of temperature change in the 21st century in this highly schematic scenario by far exceeds all IPCC projections. We did it intentionally to explore the most extreme pathway for potential sub-see permafrost degradation underneath the ESS. Model results indicated ca 1 m deepening of the upper sub-sea permafrost boundary

  20. Diversity and composition of bacterial community in soils and lake sediments from an Arctic lake area

    Directory of Open Access Journals (Sweden)

    Nengfei Wang

    2016-07-01

    Full Text Available This study assessed the diversity and composition of bacterial communities within soils and lake sediments from an Arctic lake area (London Island, Svalbard. A total of 2,987 operational taxonomic units (OTUs were identified by high throughput sequencing, targeting bacterial 16S rRNA. The samples from four sites (three samples in each site were significantly different in geochemical properties and bacterial community composition. Proteobacteria and Acidobacteria were abundant phyla in the nine soil samples, whereas Proteobacteria and Bacteroidetes were abundant phyla in the three sediment samples. Furthermore, Actinobacteria, Chlorobi, Chlorofiexi, Elusimicrobia, Firmicutes, Gemmatimonadetes, Nitrospirae, Planctomycetes, Proteobacteria significantly varied in their abundance among the four sampling sites. Additionally, members of the dominant genera, such as Clostridium, Luteolibacter, Methylibium, Rhodococus, and Rhodoplanes, were significantly different in their abundance among the four sampling sites. Besides, distance-based redundancy analysis revealed that pH (p < 0.001, water content (p < 0.01, ammonium nitrogen (NH4--N, p < 0.01, silicate silicon (SiO42--Si, p < 0.01, nitrite nitrogen (NO2--N, p < 0.05, organic carbon (p < 0.05, and organic nitrogen (p < 0.05 were the most significant factors that correlated with the bacterial community composition. The results suggest soils and sediments from a lake area in the Arctic harbor a high diversity of bacterial communities, which are influenced by many geochemical factors of Arctic environments.

  1. Biogenic volatile organic compound emissions along a high arctic soil moisture gradient.

    Science.gov (United States)

    Svendsen, Sarah Hagel; Lindwall, Frida; Michelsen, Anders; Rinnan, Riikka

    2016-12-15

    Emissions of biogenic volatile organic compounds (BVOCs) from terrestrial ecosystems are important for the atmospheric chemistry and the formation of secondary organic aerosols, and may therefore influence the climate. Global warming is predicted to change patterns in precipitation and plant species compositions, especially in arctic regions where the temperature increase will be most pronounced. These changes are potentially highly important for the BVOC emissions but studies investigating the effects are lacking. The aim of this study was to investigate the quality and quantity of BVOC emissions from a high arctic soil moisture gradient extending from dry tundra to a wet fen. Ecosystem BVOC emissions were sampled five times in the July-August period using a push-pull enclosure technique, and BVOCs trapped in absorbent cartridges were analyzed using gas chromatography-mass spectrometry. Plant species compositions were estimated using the point intercept method. In order to take into account important underlying ecosystem processes, gross ecosystem production, ecosystem respiration and net ecosystem production were measured in connection with chamber-based BVOC measurements. Highest emissions of BVOCs were found from vegetation communities dominated by Salix arctica and Cassiope tetragona, which had emission profiles dominated by isoprene and monoterpenes, respectively. These results show that emissions of BVOCs are highly dependent on the plant cover supported by the varying soil moisture, suggesting that high arctic BVOC emissions may affect the climate differently if soil water content and plant cover change.

  2. An eddy covariance derived annual carbon budget for an arctic terrestrial ecosystem (Disko, Greenland)

    Science.gov (United States)

    McConnell, Alistair; Lund, Magnus; Friborg, Thomas

    2016-04-01

    Ecosystems with underlying permafrost cover nearly 25% of the ice-free land area in the northern hemisphere and store almost half of the global soil carbon. Future climate changes are predicted to have the most pronounced effect in northern latitudes. These Arctic ecosystems are therefore subject to dramatic changes following thawing of permafrost, glacial retreat, and coastal erosion. The most dramatic effect of permafrost thawing is the accelerated decomposition and potential mobilization of organic matter stored in the permafrost. This will impact global climate through the mobilization of carbon and nitrogen accompanied by release of greenhouses gases, including carbon dioxide. This study presents the initial findings and first full annual carbon (CO2) budget, derived from eddy covariance measurements, for an Arctic landscape in West Greenland. The study site, a terrestrial Arctic maritime climate, is located at Østerlien, near Qeqertarsuaq, on the southern coast of Disko Island in central West Greenland (69° 15' N, 53° 34' W) within the transition zone from continuous to discontinuous permafrost. The mean annual air temperature is -5 C and the annual precipitation as rain is 150-200 mm. Arctic ecosystem feedback mechanisms and processes interact on micro, local and regional scales. This is further complicated by several potential feedback mechanisms likely to occur in permafrost-affected ecosystems, involving the interactions of microorganisms, vegetation and soil. The eddy covariance method allows us to interrogate the processes and drivers of land-atmosphere carbon exchange at extremely high temporary frequency (10 Hz), providing landscape-scale measurements of CO2, H2O and heat fluxes for the site, which are processed to derive daily, monthly and now, annual carbon fluxes. We discuss the scientific methodology, challenges, and analysis, as well as the practical and logistic challenges of working in the Arctic, and present an annual carbon budget

  3. Recent Trends in Permafrost Temperature From North American Sites Contributing to the Global Terrestrial Network for Permafrost

    Science.gov (United States)

    Smith, S.; Burgess, M.; Romanovsky, V.; Clow, G.; Brown, J.

    2004-05-01

    The Global Terrestrial Network for Permafrost (GTN-P) was established in 1999 to provide long-term field observations of active layer and permafrost thermal state that are required to determine the present permafrost conditions and to detect changes in permafrost stability. The data supplied by this network enhances our ability to predict the consequences of permafrost degradation associated with climate warming and to develop adaptation strategies to respond to these changes. The GTN-P contributes to the World Meteorological Organization's Global Climate Observing System and Global Terrestrial Observing System. This paper focuses on the thermal monitoring component of the GTN-P. To date, over 300 thermal monitoring sites have been identified from 16 countries for inclusion in the GTN-P. Site descriptions (metadata) and summary data are disseminated through the GTN-P web site (www.gtnp.org). Plans are being developed for a GTN-P contribution to the International Polar Year which will involve a collection of data from all monitoring sites if possible in 2006 and 2007. This paper reports initial results from North American sites. The results show that although recent warming of permafrost has been observed across the North American permafrost zone, the magnitude and timing of this warming varies. For example, warming has been observed since the early to mid 1980s in the western North American Arctic. Warming however in the Canadian eastern and high Arctic occurred in the late 1990s with cooler permafrost temperature generally occurring in the 1980s and early 1990s. These trends in permafrost temperature are consistent with air temperature trends observed since the 1970s in the Canadian Arctic. Variability in snow cover especially in the high Arctic, is also an important factor influencing the spatial and temporal trends in permafrost temperature.

  4. 表生风化作用下多年冻土土壤的理论粒径分布%Theoretical Grain Size Distribution of Permafrost Soils as a Generalized Consequence of Hypergene Processes

    Institute of Scientific and Technical Information of China (English)

    Igor E. Guryanov

    2004-01-01

    The paper discusses the distinctive features of grain size distribution of permafrost soils formed under conditions of continental lithogenesis and cryogenic weathering of rocks. As a functional consequence of surface erosion of mineral particles, the log-normal distribution of the density function of grain size is derived confirmed for any conditions and sediment types.

  5. Collaborative efforts to solve problems in permafrost science and engineering

    Science.gov (United States)

    Hinzman, Larry D.; Hinkel, Kenneth M.; Romanovsky, Vladimir E.

    2012-10-01

    Tenth International Conference on Permafrost; Salekhard, Russia, 25-29 June 2012 To recognize permafrost's growing significance in the Earth climate system, to stimulate interaction among the scientific communities, and to share results of the increasing numbers of permafrost investigations and discoveries currently taking place, the Tenth International Conference on Permafrost (TICOP) was held in late June in Salekhard, a town in the Yamal-Nenets autonomous district of Russia that is situated precisely on the Arctic Circle and underlain by discontinuous permafrost. TICOP marked the tenth iteration of the long-running conference series, which started in 1963, and is the conference's first return to Russia since the Second International Conference on Permafrost in 1973.

  6. 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

    2016-12-01

    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.

  7. 黄河源区冻土分布制图及其热稳定性特征模拟%Mapping Frozen Soil Distribution and Modeling Permafrost Stability in the Source Area of the Yellow River

    Institute of Scientific and Technical Information of China (English)

    李静; 盛煜; 吴吉春; 冯子亮; 宁作君; 胡晓莹; 张秀敏

    2016-01-01

    The source area of the Yellow River (SAYR) is located in the eastern-to-medium part of the Qing-hai-Tibet Plateau. Permafrost in the SAYR experienced remarkable degradation in the past. Taking distribution patterns of frozen soil and permafrost stability as research object, the characteristics of permafrost development and distribution patterns at various terrains and land covers were analyzed based on a large amount of field in-vestigations and the measurements. In addition, thermal features of permafrost were analyzed based on the mea-sured ground temperatures at various depths. The effects of the geological and geographic factors on permafrost distribution and thermal stability were discussed. It was indicated that:1) Permafrost was occasionally devel-oped in the various fluvial and proluvial plains with elevation generally lower than 4300 m;2) Permafrost was widely distributed in the mountains higher than 4350 m except for the sunny slope terrain, where local terrain played an important role in permafrost development and distribution;3) The combinations of local terrain, surfi-cial vegetation, soil wetness and moisture conditions all contributed to the formation and distribution of perma-frost in the low hills and mountains where elevation ranged in 4300-4350 m.Taking the annual mean ground temperature (MAGT) as the basis, an experiential-statistical MAGT-based model was constructed, of which lati-tude, longitude and elevation were set up as independent variables. Together with DEM data, permafrost MAGTs were primarily modeled using the statistically regression model. And then, the modeled results in the south-facing areas were slightly adjusted, and a secondly model was constructed to model permafrost distribu-tion in the shady areas. Thirdly, the combined modeling results were locally adjusted using the measurements. The frozen soil map in the SAYR was thus compiled. Taking 0oC as the boundary between permafrost and sea-sonally frozen soil, it was indicated

  8. Arctic soil development on a series of marine terraces on central Spitsbergen, Svalbard: a combined geochronology, fieldwork and modelling approach

    NARCIS (Netherlands)

    Meij, van der W.M.; Temme, A.J.A.M.; Kleijn, de Christian; Reimann, T.; Heuvelink, G.B.M.; Zwoliński, Zbigniew; Rachlewicz, Grzegorz; Rymer, Krzysztof; Sommer, Michael

    2016-01-01

    Soils in Arctic regions currently enjoy attention because of their sensitivity to climate change. It is therefore important to understand the natural processes and rates of development of these soils. Specifically, there is a need to quantify the rates and interactions between various landscape- and

  9. Massive remobilization of permafrost carbon during post-glacial warming

    Science.gov (United States)

    Tesi, T.; Muschitiello, F.; Smittenberg, R. H.; Jakobsson, M.; Vonk, J. E.; Hill, P.; Andersson, A.; Kirchner, N.; Noormets, R.; Dudarev, O.; Semiletov, I.; Gustafsson, Ö.

    2016-11-01

    Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming. However, direct physical indications for such PF-C release have so far been absent. Here we use the Laptev Sea (Arctic Ocean) as an archive to investigate PF-C destabilization during the last glacial-interglacial period. Our results show evidence for massive supply of PF-C from Siberian soils as a result of severe active layer deepening in response to the warming. Thawing of PF-C must also have brought about an enhanced organic matter respiration and, thus, these findings suggest that PF-C may indeed have been an important source of CO2 across the extensive permafrost domain. The results challenge current paradigms on the post-glacial CO2 rise and, at the same time, serve as a harbinger for possible consequences of the present-day warming of PF-C soils.

  10. Permafrost and organic layer interactions over a climate gradient in a discontinuous permafrost zone

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kristopher D [University of Alaska, Fairbanks; Harden, Jennifer [United States Geological Service (USGS), Menlo Park; McGuire, A. David [University of Alaska; Clark, Mark [United Stated Department of Agriculture (USDA), Natural Resources Conservation Service; Yuan, Fengming [ORNL; Finley, Andrew [Michigan State University, East Lansing

    2013-01-01

    Permafrost is tightly coupled to the organic layer, an interaction that mediates permafrost degradation in response to regional warming. We analyzed changes in permafrost occurrence (PF) and organic layer thickness (OLT) in more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships between PF, OLT, and other topographic factors were investigated using structural equation modeling in a multi-group analysis. Groups were defined by slope, soil texture type, and shallow v. deep organic layers. Permafrost probability sharply increased by 0.32 for every 10-cm OLT increase in shallow OLT soils (OLTs) due to an insulation effect, but PF decreased in deep OLT soils (OLTd) by 0.06 for every 10-cm increase. As temperature warmed, sandy soils varied little in PF or OLT, but PF in loamy and sandy soils decreased substantially. The change in OLT was more heterogeneous across soil types in some there was no change while in others OLTs soils thinned and/or OLTd soils thickened as temperature warmed. Furthermore, the rate of thickening with warming for OLTd soils was on average almost 4 times greater than the rate of thinning for OLTs soils across all soil types. If soils follow a trajectory of warming that mimics the spatial gradients found today, then heterogeneities of permafrost degradation and organic layer thinning and thickening should be considered in the regional carbon balance.

  11. 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.

  12. Development of a Coupled Framework for Simulating Interactive Effects of Frozen Soil Hydrological Dynamics in Permafrost Regions

    Science.gov (United States)

    2013-11-01

    Army Engineer Research and Development Center 3909 Halls Ferry Road Vicksburg, MS 39180-6199 Sergei Marchenko and Anna Liljedahl Geophysical ...The model is the result of coupling the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model with the Geophysical Institute Permafrost...simulates two dimensional groundwater flow and one-dimensional vadose zone flow. These two models were combined by incorporating the GIPL model into the

  13. Deeper snow alters soil nutrient availability and leaf nutrient status in high Arctic tundra

    DEFF Research Database (Denmark)

    Semenchuk, Philipp R.; Elberling, Bo; Amtorp, Cecilie;

    2015-01-01

    Nitrogen (N) mineralization, nutrient availability, and plant growth in the Arctic are often restricted by low temperatures. Predicted increases of cold-season temperatures may be important for plant nutrient availability and growth, given that N mineralization is also taking place during the cold...... season. Changing nutrient availability may be reflected in plant N and chlorophyll content and lead to increased photosynthetic capacity, plant growth, and ultimately carbon (C) assimilation by plants. In this study, we increased snow depth and thereby cold-season soil temperatures in high Arctic......, Bistorta vivipara, and Luzula arcuata at peak season. Nutrient availability was significantly higher with increased snow depth in the two mesic meadow vegetation types, but not in the drier heath vegetation. Nitrogen concentrations and delta N-15 values of Salix leaves were significantly higher in all...

  14. Metabolic and growth characteristics of novel diverse microbes isolated from deep cores collected at the Next Generation Ecosystem Experiment (NGEE)-Arctic site in Barrow, Alaska

    Science.gov (United States)

    Chakraborty, R.; Pettenato, A.; Tas, N.; Hubbard, S. S.; Jansson, J.

    2013-12-01

    The Arctic is characterized by vast amounts of carbon stored in permafrost and is an important focal point for the study of climate change as increasing temperature may accelerate microbially mediated release of Carbon stored in permafrost into the atmosphere as CO2 and CH4. Yet surprisingly, very little is known about the vulnerability of permafrost and response of microorganisms in the permafrost to their changing environment. This deficiency is largely due to the difficulty in study of largely uncultivated and unknown permafrost microbes. As part of the U.S. Department of Energy (DOE) Next Generation Ecosystem Experiment (NGEE) in the Arctic, we collected permafrost cores in an effort to isolate resident microbes. The cores were from the Barrow Environmental Observatory (BEO), located at the northern most location on the Alaskan Arctic Coastal Plain near Barrow, AK, and up to 3m in depth. In this location, permafrost starts from 0.5m in depth and is characterized by variable water content and higher pH than surface soils. Enrichments for heterotrophic bacteria were initiated at 4°C and 1°C in the dark in several different media types, under both aerobic and anaerobic conditions. Positive enrichments were identified by an increase in optical density and cell counts after incubation period ranging from two to four weeks. After serial transfers into fresh media, individual colonies were obtained on agar surface. Several strains were isolated that include Firmicutes such as Bacillus, Clostridium, Sporosarcina, and Paenibacillus species and Iron-reducing Betaproteobacteria such as Rhodoferax species. In addition, methanogenic enrichments continue to grow and produce methane gas at 2°C. In this study, we present the characterization, carbon substrate utilization, pH, temperature and osmotic tolerance, as well as the effect of increasing climate change parameters on the growth rate and respiratory gas production from these permafrost isolates.

  15. Arctic and subarctic environmental analyses utilizing ERTS-1 imagery. [permafrost sediment transport, snow cover, ice conditions, and water runoff in Alaska

    Science.gov (United States)

    Anderson, D. M.; Mckim, H. L.; Haugen, R. K.; Gatto, L. W.; Slaughter, C. W.; Marlar, T. L. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Physiognomic landscape features were used as geologic and vegetative indicators in preparation of a surficial geology, vegetation, and permafrost map at a scale of 1:1 million using ERTS-1 band 7 imagery. The detail from this map compared favorably with USGS maps at 1:250,000 scale. Physical boundaries mapped from ERTS-1 imagery in combination with ground truth obtained from existing small maps and other sources resulted in improved and more detailed maps of permafrost terrain and vegetation for the same area. ERTS-1 imagery provides for the first time, a means of monitoring the following regional estuarine processes: daily and periodic surface water circulation patterns; changes in the relative sediment load of rivers discharging into the inlet; and, several local patterns not recognized before, such as a clockwise back eddy offshore from Clam Gulch and a counterclockwise current north of the Forelands. Comparison of ERTS-1 and Mariner imagery has revealed that the thermokarst depressions found on the Alaskan North Slope and polygonal patterns on the Yukon River Delta are possible analogs to some Martian terrain features.

  16. Remediation of oil-contaminated soil in Arctic Climate

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland; Fritt-Rasmussen, Janne; Rodrigo, Ana;

    Oil spill is a problem in towns in Greenland, where oil is used for heating and transport. The problem may increase in the future with expected oil exploitation in Greenlandic marine areas and related terrestrial activities. Oil undergoes natural microbial degradation in which nutrients, temperat....... Experiments have been made with excavated oil-contaminated soil from the Greenlandic town Sisimiut to study different low-tech and low-cost solutions for remediation of oil-contamination...

  17. Remediation of oil-contaminated soil in Arctic Climate

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland; Fritt-Rasmussen, Janne; Rodrigo, Ana P.;

    Oil spill is a problem in towns in Greenland, where oil is used for heating and transport. The problem may increase in the future with expected oil exploitation in Greenlandic marine areas and related terrestrial activities. Oil undergoes natural microbial degradation in which nutrients, temperat...... have been made with excavated oil-contaminated soil from the Greenlandic town Sisimiut to study different low-tech and low-cost solutions for remediation of oil-contamination....

  18. Metagenomic analysis of the bioremediation of diesel-contaminated Canadian high arctic soils.

    Directory of Open Access Journals (Sweden)

    Etienne Yergeau

    Full Text Available As human activity in the Arctic increases, so does the risk of hydrocarbon pollution events. On site bioremediation of contaminated soil is the only feasible clean up solution in these remote areas, but degradation rates vary widely between bioremediation treatments. Most previous studies have focused on the feasibility of on site clean-up and very little attention has been given to the microbial and functional communities involved and their ecology. Here, we ask the question: which microorganisms and functional genes are abundant and active during hydrocarbon degradation at cold temperature? To answer this question, we sequenced the soil metagenome of an ongoing bioremediation project in Alert, Canada through a time course. We also used reverse-transcriptase real-time PCR (RT-qPCR to quantify the expression of several hydrocarbon-degrading genes. Pseudomonas species appeared as the most abundant organisms in Alert soils right after contamination with diesel and excavation (t = 0 and one month after the start of the bioremediation treatment (t = 1m, when degradation rates were at their highest, but decreased after one year (t = 1y, when residual soil hydrocarbons were almost depleted. This trend was also reflected in hydrocarbon degrading genes, which were mainly affiliated with Gammaproteobacteria at t = 0 and t = 1m and with Alphaproteobacteria and Actinobacteria at t = 1y. RT-qPCR assays confirmed that Pseudomonas and Rhodococcus species actively expressed hydrocarbon degradation genes in Arctic biopile soils. Taken together, these results indicated that biopile treatment leads to major shifts in soil microbial communities, favoring aerobic bacteria that can degrade hydrocarbons.

  19. Cryostratigraphy and Main Physical Properties of Active Layer Soils and Upper Horizon of Permafrost at the Barrow Environmental Observatory Research Site.

    Science.gov (United States)

    Kholodov, A. L.; Liljedahl, A.; Romanovsky, V. E.; Cable, W.

    2014-12-01

    Complete understanding of the results of geophysical survey, microbiological and biogeochemical analyzes of soil cores in the Arctic environment impossible without detail description of the frozen soil and its physical properties determination. Cryostratigraphyc features i.e. total ice content and forms of ice patterns reflects the important processes such as water migration due to freezing in frozen active layer soils and history of sedimentation and freezing in underlying perennially frozen deposits. That plays significant role in biogeochemical processes that take place in the Arctic ecosystem. Current research was based on description and analyzing of 8 cores taken during 2012 and 2013 coring campaigne had been done at the Barrow Environmental Observatory research site. Cores were taken from different types of polygons and analyzed on lithological composition, soil density, ice content and thermal conductivity. Volumetric ice content within the active layer composed by organic soil consists of 70 to 80% and within silt one - less than 60%. Ice content of underlying syncryogenic perennial frozen deposits is about 70%. No clear evidences of soil moisture redistribution due to freezing of active layer were noticed in the cores composed by the organic soil. Organic soil does not have any clear cryogenic structures. Ice usually fills the pores and follows the plants fibers. Mineral soil has recticulated cryogenic structure (ice forms grid like patterns with vertically oriented cells) with some thin (up to 2 cm thick) layers of soil particles and aggregates suspended in ice. Thermal conductivity of frozen samples varies in the range from 1.5 to 2.8 W/(m*°K). It has a positive correlation with soil density and negative with gravimetric ice content (see figure below). Mineral soils have a higher bulk density and average thermal conductivity in the range 2.15 W/(m*°K), organic soils have a lower density and average thermal conductivity about 2 W/(m*°K). Samples

  20. Consequences of artic ground squirrels on soil carbon loss from Siberian tundra

    Science.gov (United States)

    Golden, N. A.; Natali, S.; Zimov, N.

    2014-12-01

    A large pool of organic carbon (C) has been accumulating in the Arctic for thousands of years. Much of this C has been frozen in permafrost and unavailable for microbial decomposition. As the climate warms and permafrost thaws, the fate of this large C pool will be driven not only by climatic conditions, but also by ecosystem changes brought about by arctic animal populations. In this project we studied arctic ground squirrels (Spermophilus parryii), which are widely-distributed throughout the Arctic. These social mammals create subterranean burrows that mix soil layers, increase aeration, alter soil moisture and temperature, and redistribute soil nutrients, all of which may impact microbial decomposition. We examined the effects of arctic ground squirrel activity on soil C mineralization in dry heath tundra underlain by continuous permafrost in the Kolyma River watershed in northeast Siberia, Russia. Vegetation cover was greatly reduced on the ground squirrel burrows (80% of ground un-vegetated), compared to undisturbed sites (35% of ground un-vegetated). Soils from ground squirrel burrows were also significantly dryer and warmer. To examine effects of ground squirrel activity on microbial respiration, we conducted an 8-day incubation of soil fromburrows and from adjacent undisturbed tundra. In addition, we assessed the impact of nutrient addition by including treatments with low and high levels of nitrogen addition. Microbial respiration (per gram soil) was three-fold higher in incubated soils from the undisturbed sites compared to soils collected from the burrows. The lower rates of respiration from the disturbed soils may have been a result of lower carbon quality or low soil moisture. High nitrogen addition significantly increased respiration in the undisturbed soils, but not in the disturbed burrow soils, which suggests that microbial respiration in the burrow soils was not primarily limited by nitrogen. These results demonstrate the importance of wildlife

  1. Scaling Issues Between Plot and Satellite Radiobrightness Observations of Arctic Tundra

    Science.gov (United States)

    Kim, Edward J.; England, Anthony W.; Judge, Jasmeet; Zukor, Dorothy J. (Technical Monitor)

    2000-01-01

    Data from generation of satellite microwave radiometer will allow the detection of seasonal to decadal changes in the arctic hydrology cycle as expressed in temporal and spatial patterns of moisture stored in soil and snow This nw capability will require calibrated Land Surface Process/Radiobrightness (LSP/R) model for the principal terrains found in the circumpolar Arctic. These LSP/R models can than be used in weak constraint. Dimensional Data Assimilation (DDA)of the daily satellite observation to estimate temperature and moisture profiles within the permafrost in active layer.

  2. 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.

  3. Potential changes in arctic seasonality and plant communities may impact tundra soil chemistry and carbon dynamics

    Science.gov (United States)

    Crow, S.; Cooper, E.; Beilman, D.; Filley, T.; Reimer, P.

    2009-04-01

    On the Svalbard archipelago, as in other high Arctic regions, tundra soil organic matter (SOM) is primarily plant detritus that is largely stabilized by cold, moist conditions and low nitrogen availability. However, the resistance of SOM to decomposition is also influenced by the quality of organic matter inputs to soil. Different plant communities are likely to give different qualities to SOM, especially where lignin-rich woody species encroach into otherwise graminoid and bryophyte-dominated regions. Arctic woody plant species are particularly sensitive to changes in temperature, snow cover, and growing season length. In a changing environment, litter chemistry may emerge as an important control on tundra SOM stabilization. In summer 2007, we collected plant material and soil from the highly-organic upper horizon (appx. 0-5 cm) and the mineral-dominated lower horizon (appx. 5-10cm) from four locations in the southwest facing valleys of Svalbard, Norway. The central goal of the ongoing experiment is to determine whether a greater abundance of woody plants could provide a negative feedback to warming impacts on the carbon (C) balance of Arctic soils. Towards this, we used a combination of plant biopolymer analyses (cupric oxide oxidation and quantification of lignin-derived phenols and cutin/suberin-derived aliphatics) and radiocarbon-based estimates of C longevity and mean residence time (MRT) to characterize potential links between plant type and soil C pools. We found that graminoid species regenerate above- and belowground tissue each year, whereas woody species (Cassiope tetragona and Dryas octopetala) regenerated only leaves yearly. In contrast, C within live branches and roots persisted for 15-18 yr on average. Leaves from woody species remained nearly intact in surface litter for up to 20 yr without being incorporated into the upper soil horizon. Leaves from both graminoid and woody species were concentrated in lignin-derived phenols relative to roots, but

  4. 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).

  5. Arctic soil development on a series of marine terraces on central Spitsbergen, Svalbard: a combined geochronology, fieldwork and modelling approach

    Science.gov (United States)

    van der Meij, W. Marijn; Temme, Arnaud J. A. M.; de Kleijn, Christian M. F. J. J.; Reimann, Tony; Heuvelink, Gerard B. M.; Zwoliński, Zbigniew; Rachlewicz, Grzegorz; Rymer, Krzysztof; Sommer, Michael

    2016-06-01

    Soils in Arctic regions currently enjoy attention because of their sensitivity to climate change. It is therefore important to understand the natural processes and rates of development of these soils. Specifically, there is a need to quantify the rates and interactions between various landscape- and soil-forming processes. Soil chronosequences are ideal natural experiments for this purpose. In this contribution, we combine field observations, luminescence dating and soil-landscape modelling to improve and test our understanding of Arctic soil formation. The field site is a Holocene chronosequence of gravelly raised marine terraces in central Spitsbergen. Field observations show that soil-landscape development is mainly driven by weathering, silt translocation, aeolian deposition and rill erosion. Spatial soil variation is mainly caused by soil age, morphological position within a terrace and depth under the surface. Luminescence dating confirmed existing radiocarbon dating of the terraces, which are between ˜ 1.5 and ˜ 13.3 ka old. The soil-landscape evolution model LORICA was used to test our hypothesis that the field-observed processes indeed dominate soil-landscape development. Model results additionally indicated the importance of aeolian deposition as a source of fine material in the subsoil for both sheltered and vegetated trough positions and barren ridge positions. Simulated overland erosion was negligible. Consequently, an un-simulated process must be responsible for creating the observed erosion rills. Dissolution and physical weathering both play a major role. However, using present-day soil observations, the relative contribution of physical and chemical weathering could not be disentangled. Discrepancies between field and model results indicate that soil formation is non-linear and driven by spatially and temporally varying boundary conditions which were not included in the model. To conclude, Arctic soil and landscape development appears to be more

  6. Soil fauna communities and microbial respiration in high Arctic tundra soils at Zackenberg, Northeast Greenland

    DEFF Research Database (Denmark)

    Sørensen, Louise I.; Holmstrup, Martin; Maraldo, Kristine;

    2006-01-01

    densities (naked amoeba and heterotrophic flagellates) were equal. Respiration rate of unamended soil was similar in soil from the three plots. However, a higher respiration rate increase in carbon + nutrient amended soil and the higher densities of soil fauna (with the exception of mites and protozoa...

  7. Permafrost and organic layer interactions over a climate gradient in a discontinuous permafrost zone

    Science.gov (United States)

    Johnson, Kristofer D.; Harden, Jennifer W.; McGuire, A. David; Clark, Mark; Yuan, Fengming; Finley, Andrew O.

    2013-01-01

    Permafrost is tightly coupled to the organic soil layer, an interaction that mediates permafrost degradation in response to regional warming. We analyzed changes in permafrost occurrence and organic layer thickness (OLT) using more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships between permafrost probability (PF), OLT, and other topographic factors were investigated using structural equation modeling in a multi-group analysis. Groups were defined by slope, soil texture type, and shallow (<28 cm) versus deep organic (≥28 cm) layers. The probability of observing permafrost sharply increased by 0.32 for every 10-cm OLT increase in shallow OLT soils (OLTs) due to an insulation effect, but PF decreased in deep OLT soils (OLTd) by 0.06 for every 10-cm increase. Across the MAT gradient, PF in sandy soils varied little, but PF in loamy and silty soils decreased substantially from cooler to warmer temperatures. The change in OLT was more heterogeneous across soil texture types—in some there was no change while in others OLTs soils thinned and/or OLTd soils thickened at warmer locations. Furthermore, when soil organic carbon was estimated using a relationship with thickness, the average increase in carbon in OLTd soils was almost four times greater compared to the average decrease in carbon in OLTs soils across all soil types. If soils follow a trajectory of warming that mimics the spatial gradients found today, then heterogeneities of permafrost degradation and organic layer thinning and thickening should be considered in the regional carbon balance.

  8. Geodynamics, Seismicity, Minerageny and Ecology of Arctic Regions

    Science.gov (United States)

    Kutinov, Y. G.

    The researches of Arctic region is necessary for beginning from delimitation of Arctic. Geographically concept "Arctic" uncertain enough. There is a set of approach to definition of its borders and set the variants of these borders (eternal permafrost, boreal tayga, drifting ice, temperature, etc.). Most correct the point of view of Ecology is realization of Arctic borders on borders of the Arctic geo - depression. Such approach allows to consider in a complex migration of natural substance and polluting substance from orogenes to deep-water hollows of Arctic Ocean. On other hand, it is necessary to take into account natural power flows from zone of Mid-Arctic ridge system at Arctic Ocean to continental land, that is opposition direction process. The certificates of such influence at different levels of Earth's crust already has collected enough (speed of seismic wave on Moho discontinuity; modern vertical movement of Earth's crust; distribution of temperature on depth; structure of basement, etc.). During the last 250 million years the Arctic geo-depression has been developing as an autonomous region with circumpolar zonality, and mass-and-energy transfer in its bowlers as well as shitting of lithospheric plates and expansion of the ocean are caused by rotational forces under conditions of an expanding planet. Four types of geoecological structures have been recorded on the basis of deep structures, position in the over-all structures of regions, place in geological history of its evolution, time of appearance, geodynamic regimes , seismicity, structural-morphological features, specific form of appearance and composition of magmatic and sedimentary formations, compositions of soil, specific metallogenic nature, types of human activity, etc. It is tectonic Segments of Earth, as geoecological global structures; the continental marginal perioceanic zones; the branches of continental marginal perioceanic zones; the mineragenic province. The main criteria of ecological

  9. Evidence of in situ microbial activity and sulphidogenesis in perennially sub-0 °C and hypersaline sediments of a high Arctic permafrost spring.

    Science.gov (United States)

    Lamarche-Gagnon, Guillaume; Comery, Raven; Greer, Charles W; Whyte, Lyle G

    2015-01-01

    The lost hammer (LH) spring perennially discharges subzero hypersaline reducing brines through thick layers of permafrost and is the only known terrestrial methane seep in frozen settings on Earth. The present study aimed to identify active microbial communities that populate the sediments of the spring outlet, and verify whether such communities vary seasonally and spatially. Microcosm experiments revealed that the biological reduction of sulfur compounds (SR) with hydrogen (e.g., sulfate reduction) was potentially carried out under combined hypersaline and subzero conditions, down to -20 °C, the coldest temperature ever recorded for SR. Pyrosequencing analyses of both 16S rRNA (i.e., cDNA) and 16S rRNA genes (i.e., DNA) of sediments retrieved in late winter and summer indicated fairly stable bacterial and archaeal communities at the phylum level. Potentially active bacterial and archaeal communities were dominated by clades related to the T78 Chloroflexi group and Halobacteria species, respectively. The present study indicated that SR, hydrogenotrophy (possibly coupled to autotrophy), and short-chain alkane degradation (other than methane), most likely represent important, previously unaccounted for, metabolic processes carried out by LH microbial communities. Overall, the obtained findings provided additional evidence that the LH system hosts active communities of anaerobic, halophilic, and cryophilic microorganisms despite the extreme conditions in situ.

  10. 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. T......). The results showed that the use of a reflective surface (white paint) will reduce the thickness of the active layer and avoid permafrost degradation underneath the embankment. This should promote the interest in the development and use of light-colored asphalt pavement materials....

  11. 多年冻土地区建筑物地基的热稳定性技术%Technique for Thermal Stabilization of Soils at Bases of Structures in Permafrost Regions

    Institute of Scientific and Technical Information of China (English)

    Refik M. Bayasan; Anatoly G. Korotchenko; Anatoly D. Lobanov; Grigory P. Pustovoit

    2004-01-01

    Thermal stabilization of soils (including freezing of thawed soils and cooling of permafrost) is known to be the effective method providing stable support for buildings and structures in cold regions.Seasonal thermo-stabilizers (STS) are mainly used in construction. The predicted climate warming because of natural and man-caused factors determines wide application of STS in permafrost regions. A STS transfers heat from its underground part (evaporator) to the aerial part (condenser) owing to natural temperature difference between them during a cold season. We have been working out and manufacturing different types of two-phase, vapor-liquid STS. Aluminum alloys are used in our STS to prevent corrosion and to increase their efficiency. They are successfully used in the northern regions of Western Siberia, in particular, at the railway Obskaya Bovanenkovo. The paper presents some technical parameters of new STS, the results of their experimental study and computer simulation, as well as experience features.

  12. Soil pH is a Key Determinant of Soil Fungal Community Composition in the Ny-Ålesund Region, Svalbard (High Arctic).

    Science.gov (United States)

    Zhang, Tao; Wang, Neng-Fei; Liu, Hong-Yu; Zhang, Yu-Qin; Yu, Li-Yan

    2016-01-01

    This study assessed the fungal community composition and its relationships with properties of surface soils in the Ny-Ålesund Region (Svalbard, High Arctic). A total of thirteen soil samples were collected and soil fungal community was analyzed by 454 pyrosequencing with fungi-specific primers targeting the rDNA internal transcribed spacer (ITS) region. The following eight soil properties were analyzed: pH, organic carbon (C), organic nitrogen (N), ammonium nitrogen (NH4 (+)-N), silicate silicon (SiO4 (2-)-Si), nitrite nitrogen (NO2 (-)-N), phosphate phosphorus (PO4 (3-)-P), and nitrate nitrogen (NO3 (-)-N). A total of 57,952 reads belonging to 541 operational taxonomic units (OTUs) were found. of these OTUs, 343 belonged to Ascomycota, 100 to Basidiomycota, 31 to Chytridiomycota, 22 to Glomeromycota, 11 to Zygomycota, 10 to Rozellomycota, whereas 24 belonged to unknown fungi. The dominant orders were Helotiales, Verrucariales, Agaricales, Lecanorales, Chaetothyriales, Lecideales, and Capnodiales. The common genera (>eight soil samples) were Tetracladium, Mortierella, Fusarium, Cortinarius, and Atla. Distance-based redundancy analysis (db-rda) and analysis of similarities (ANOSIM) revealed that soil pH (p = 0.001) was the most significant factor in determining the soil fungal community composition. Members of Verrucariales were found to predominate in soils of pH 8-9, whereas Sordariales predominated in soils of pH 7-8 and Coniochaetales predominated in soils of pH 6-7. The results suggest the presence and distribution of diverse soil fungal communities in the High Arctic, which can provide reliable data for studying the ecological responses of soil fungal communities to climate changes in the Arctic.

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

    NARCIS (Netherlands)

    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.

    2013-01-01

    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 an

  14. Effects of Temperature Changes on Biodegradation of Petroleum Hydrocarbons in Contaminated Soils from an Arctic Site

    Science.gov (United States)

    Chang, W.; Klemm, S.; Whyte, L.; Ghoshal, S.

    2009-05-01

    Bioremediation is being considered as a cost-effective and a minimally disruptive remedial option at remote sites in the Arctic and sub-Arctic impacted by petroleum NAPL contamination. The implementation of on-site bioremediation in cold environments has been generally limited in the short, non-freezing summer months since ground remains frozen for 8-9 months of the year. This study evaluates the effect of different temperature regimes on petroleum hydrocarbon biodegradation rates and extent, as well as on the microbial activity. A series of pilot-scale landfarming bioremediation experiments (1 m×0.6 m×0.35 m soil tank dimension) was performed using aged, petroleum fuel-contaminated soils shipped from Resolution Island, Nunavut, Canada. These experiments were conducted under the following temperature conditions: (1) variable daily average field temperatures (1 to 10°C) representative of summers at the site; (2) constant mean temperature-mode with 6°C, representing typical stable laboratory incubation; and (3) under seasonal freeze-thaw conditions (-8°C to 10°C). Data to be presented include changes with time of petroleum hydrocarbons concentration fractionated by C-lengths, soil moisture (unfrozen water) contents, O2 and CO2 concentrations in soil pore gas, microbial population size and community composition in nutrient- amended and untreated landfarms. Hydrocarbon biodegradation and heterotrophic respiration activity was more rapid under the variable temperature cycle (1 to 10°C) than at a constant average temperature of 6°C, and total petroleum hydrocarbon (TPH) concentrations were reduced by 55% due to biodegradation over a 60 day test period under the variable temperature regime, compared to only 21% in soil tanks which were subjected to a constant temperature of 6°C. Shifts in microbial community were clearly observed in the both temperature modes using PCR-DGGE analyses and the emergence of a hydrocarbon-degrading population, Alkanindiges, was

  15. Coupled Northern Hemisphere permafrost-ice sheet evolution over the last glacial cycle

    Directory of Open Access Journals (Sweden)

    M. Willeit

    2015-02-01

    Full Text Available Permafrost influences a number of processes which are relevant for local and global climate. For example, it is well known that permafrost plays an important role in global carbon and methane cycles. Less is known about the interaction between permafrost and ice sheets. In this study a permafrost module is included in the Earth system model CLIMBER-2 and the coupled Northern Hemisphere (NH permafrost-ice sheet evolution over the last glacial cycle is explored. The model performs generally well at reproducing present-day permafrost extent and thickness. Modelled permafrost thickness is sensitive to the values of ground porosity, thermal conductivity and geothermal heat flux. Permafrost extent at the last glacial maximum (LGM agrees well with reconstructions and previous modelling estimates. Present-day permafrost thickness is far from equilibrium over deep permafrost regions. Over Central Siberia and the Arctic Archipelago permafrost is presently up to 200–500 m thicker than it would be at equilibrium. In these areas, present-day permafrost depth strongly depends on the past climate history and simulations indicate that deep permafrost has a memory of surface temperature variations going back to at least 800 kya. Over the last glacial cycle permafrost has a relatively modest impact on simulated NH ice sheet volume except at LGM, when including permafrost increases ice volume by about 15 m sea level equivalent. This is explained by a delayed melting of the ice base from below by the geothermal heat flux when the ice sheet sits on a porous sediment layer and permafrost has to be melted first. Permafrost affects ice sheet dynamics only when ice extends over areas covered by thick sediments, which is the case at LGM.

  16. Non-linear CO2 flux response to seven years of experimentally induced permafrost thaw.

    Science.gov (United States)

    Mauritz, Marguerite; Bracho, Rosvel; Celis, Gerardo; Hutchings, Jack; Natali, Susan M; Pegoraro, Elaine; Salmon, Verity G; Schädel, Christina; Webb, Elizabeth E; Schuur, Edward A G

    2017-02-16

    Rapid Arctic warming is expected to increase global greenhouse gas concentrations as permafrost thaw exposes immense stores of frozen carbon (C) to microbial decomposition. Permafrost thaw also stimulates plant growth, which could offset C loss. Using data from seven years of experimental Air and Soil warming in moist acidic tundra, we show that Soil warming had a much stronger effect on CO2 flux than Air warming. Soil warming caused rapid permafrost thaw and increased ecosystem respiration (Reco), gross primary productivity (GPP), and net summer CO2 storage (NEE). Over seven years Reco, GPP, and NEE also increased in Control (i.e., ambient plots), but this change could be explained by slow thaw in Control areas. In the initial stages of thaw, Reco , GPP, and NEE increased linearly with thaw across all treatments, despite different rates of thaw. As thaw in Soil warming continued to increase linearly, ground surface subsidence created saturated micro-sites, and suppressed Reco , GPP, and NEE. However Reco and GPP remained high in areas with large Eriophorum vaginatum biomass. In general NEE increased with thaw, but was more strongly correlated with plant biomass than thaw, indicating that higher Reco in deeply thawed areas during summer months was balanced by GPP. Summer CO2 flux across treatments fit a single quadratic relationship that captured the functional response of CO2 flux to thaw, water table depth, and plant biomass. These results demonstrate the importance of indirect thaw effects on CO2 flux: plant growth and water table dynamics. Non-summer Reco models estimated that the area was an annual CO2 source during all years of observation. Non-summer CO2 loss in warmer, more deeply thawed soils exceeded the increases in summer GPP, and thawed tundra was a net annual CO2 source. This article is protected by copyright. All rights reserved.

  17. Integrated metagenomics and field measurements of polygon features at the NGEE-Arctic Barrow site

    Science.gov (United States)

    Tas, N.; Wu, Y.; Smith, L. J.; Ulrich, C.; Kneafsey, T. J.; Torn, M. S.; Hubbard, S. S.; Wullschleger, S. D.; Jansson, J.

    2013-12-01

    Arctic soils contain an estimated 12-42% of terrestrial carbon, most of which is sequestered in permafrost. High latitudes have experienced the greatest regional warming in recent decades and observations suggest that permafrost degradation is now commonly observed in the region. With increasing global temperatures, permafrost soils are becoming a potential source of greenhouse gas (GHG) emissions. Because of widespread permafrost thaw much of the soil organic matter may be available for rapid mineralization by microorganisms in the soil. Yet little is known about the vulnerability of permafrost and the potential response of soil microorganisms to availability of new carbon sources. On the Alaskan North Slope the collapse and rise of soil due to formation of ice wedges and permafrost thaw create distinct features called polygons. As part of the U.S. Department of Energy (DOE) Next Generation Ecosystem Experiment (NGEE) in the Arctic, we aimed to determine the distribution of microbial populations across a range of polygon features and to correlate the microbial data to GHG flux data. To determine the microbial community distribution and metabolic potential, we collected seasonally thawed active layer soil samples along two polygon transects (Site 0 and AB), including high-centered, transitional and low-centered polygons. Illumina HiSeq technology was used to sequence 16SrRNA genes and metagenomes from these active layer soils. The sequence data was correlated to GHG flux measurements and to environmental data from the site, including geophysical and geochemical soil characteristics. Both the microbial communities and the flux measurements varied along the polygon transect. Each polygon had a distinct microbial community structure; however, these microbial communities shared many metabolic capabilities. For example, many genes involved in degradation of chitin could be found all three polygons. Functional genes involved in methanogenesis and CH4-flux measurements

  18. Bioremediation of weathered petroleum hydrocarbon soil contamination in the Canadian High Arctic: laboratory and field studies.

    Science.gov (United States)

    Sanscartier, David; Laing, Tamsin; Reimer, Ken; Zeeb, Barbara

    2009-11-01

    The bioremediation of weathered medium- to high-molecular weight petroleum hydrocarbons (HCs) in the High Arctic was investigated. The polar desert climate, contaminant characteristics, and logistical constraints can make bioremediation of persistent HCs in the High Arctic challenging. Landfarming (0.3 m(3) plots) was tested in the field for three consecutive years with plots receiving very little maintenance. Application of surfactant and fertilizers, and passive warming using a greenhouse were investigated. The field study was complemented by a laboratory experiment to better understand HC removal mechanisms and limiting factors affecting bioremediation on site. Significant reduction of total petroleum HCs (TPH) was observed in both experiments. Preferential removal of compounds nC16 occurred, whereas in the field, TPH reduction was mainly limited to removal of compounds nC16 was observed in the fertilized field plots only. The greenhouse increased average soil temperatures and extended the treatment season but did not enhance bioremediation. Findings suggest that temperature and low moisture content affected biodegradation of HCs in the field. Little volatilization was measured in the laboratory, but this process may have been predominant in the field. Low-maintenance landfarming may be best suited for remediation of HCs compounds

  19. Modelling unfrozen water content in a silty clay permafrost deposit

    DEFF Research Database (Denmark)

    Agergaard, Frederik Ancker; Ingeman-Nielsen, Thomas

    2011-01-01

    The mechanical properties of both unfrozen soils and permafrost soils are influenced by the amount of unfrozen water in the pore space. When dealing with foundation engineering in permafrost areas it is essential to estimate the unfrozen water content (wu). This paper deals with the establishing...... of a calibration equation for determining the unfrozen water content of a Greenlandic silty clay permafrost deposit. Calibration experiments have been conducted for water contents in the interval 0 – 10 % at both 5 °C and 22 °C. Calibration equations are verified against permittivity data from a permafrost core...... of material properties similar to the test soil. The calibration for 5°C is seen to make a good fit to the permafrost core data. Further experiments should be performed in order to extend the range of water contents tested and hence the range of validity of the calibration equation....

  20. Islands of the Arctic

    Science.gov (United States)

    Overpeck, Jonathan

    2004-02-01

    Few environments on Earth are changing more dramatically than the Arctic. Sea ice retreat and thinning is unprecedented in the period of the satellite record. Surface air temperatures are the warmest in centuries. The biology of Arctic lakes is changing like never before in millennia. Everything is pointing to the meltdown predicted by climate model simulations for the next 100 years. At the same time, the Arctic remains one of the most pristine and beautiful places on Earth. For both those who know the Arctic and those who want to know it, this book is worth its modest price. There is much more to the Arctic than its islands, but there's little doubt that Greenland and the major northern archipelagos can serve as a great introduction to the environment and magnificence of the Arctic. The book uses the islands of the Arctic to give a good introduction to what the Arctic environment is all about. The first chapter sets the stage with an overview of the geography of the Arctic islands, and this is followed by chapters that cover many key aspects of the Arctic: the geology (origins), weather and climate, glaciers, ice sheets, sea ice, permafrost and other frozen ground issues, coasts, rivers, lakes, animals, people, and environmental impacts. The material is pitched at a level well suited for the interested layperson, but the book will also appeal to those who study the science of the Arctic.

  1. Review of methane mitigation technologies with application to rapid release of methane from the Arctic.

    Science.gov (United States)

    Stolaroff, Joshuah K; Bhattacharyya, Subarna; Smith, Clara A; Bourcier, William L; Cameron-Smith, Philip J; Aines, Roger D

    2012-06-19

    Methane is the most important greenhouse gas after carbon dioxide, with particular influence on near-term climate change. It poses increasing risk in the future from both direct anthropogenic sources and potential rapid release from the Arctic. A range of mitigation (emissions control) technologies have been developed for anthropogenic sources that can be developed for further application, including to Arctic sources. Significant gaps in understanding remain of the mechanisms, magnitude, and likelihood of rapid methane release from the Arctic. Methane may be released by several pathways, including lakes, wetlands, and oceans, and may be either uniform over large areas or concentrated in patches. Across Arctic sources, bubbles originating in the sediment are the most important mechanism for methane to reach the atmosphere. Most known technologies operate on confined gas streams of 0.1% methane or more, and may be applicable to limited Arctic sources where methane is concentrated in pockets. However, some mitigation strategies developed for rice paddies and agricultural soils are promising for Arctic wetlands and thawing permafrost. Other mitigation strategies specific to the Arctic have been proposed but have yet to be studied. Overall, we identify four avenues of research and development that can serve the dual purposes of addressing current methane sources and potential Arctic sources: (1) methane release detection and quantification, (2) mitigation units for small and remote methane streams, (3) mitigation methods for dilute (methane streams, and (4) understanding methanotroph and methanogen ecology.

  2. Different shapes of constructions and their effects on permafrost

    Science.gov (United States)

    Vaganova, Nataliia; Filimonov, M. Yu.

    2016-12-01

    A heat transfer model of thermal fields in permafrost soil as a result of operation of different constructions is considered. Some positions(shapes) of engineering objects are compared in view to estimate its reliability and decrease the thermal influence on permafrost.

  3. Limnological characteristics of 56 lakes in the Central Canadian Arctic Treeline Region

    Directory of Open Access Journals (Sweden)

    John P. SMOL

    2003-02-01

    Full Text Available Measured environmental variables from 56 lakes across the Central Canadian Treeline Region exhibited clear limnological differences among subpolar ecozones, reflecting strong latitudinal changes in biome characteristics (e.g. vegetation, permafrost, climate. Principal Components Analysis (PCA clearly separated forested sites from tundra sites based on distinct differences in limnological characteristics. Increases in major ions and related variables (e.g. dissolved inorganic carbon, DIC were higher in boreal forest sites in comparison to arctic tundra sites. The higher values recorded in the boreal forest lakes may be indirectly related to differences in climatic factors in these zones, such as the degree of permafrost development, higher precipitation and runoff, duration of ice-cover on the lakes, and thicker and better soil development. Similar to trends observed in DIC, substantially higher values for dissolved organic carbon (DOC were measured in boreal forest lakes than in arctic tundra lakes. This was likely due to higher amounts of catchment-derived DOC entering the lakes from coniferous leaf litter sources. Relative to arctic tundra lakes, boreal forest lakes had higher nutrient concentrations, particularly total nitrogen (TN, likely due to warmer conditions, a longer growing season, and higher precipitation, which would enhance nutrient cycling and primary productivity. Results suggest that modern aquatic environments at opposite sides of the central Canadian arctic treeline (i.e. boreal forest and arctic tundra exhibit distinct differences in water chemistry and physical conditions. These limnological trends may provide important information on possible future changes with additional warming.

  4. Bacterial communities involved in soil formation and plant establishment triggered by pyrite bioweathering on arctic moraines.

    Science.gov (United States)

    Mapelli, Francesca; Marasco, Ramona; Rizzi, Agostino; Baldi, Franco; Ventura, Stefano; Daffonchio, Daniele; Borin, Sara

    2011-02-01

    In arctic glacier moraines, bioweathering primed by microbial iron oxidizers creates fertility gradients that accelerate soil development and plant establishment. With the aim of investigating the change of bacterial diversity in a pyrite-weathered gradient, we analyzed the composition of the bacterial communities involved in the process by sequencing 16S rRNA gene libraries from different biological soil crusts (BSC). Bacterial communities in three BSC of different morphology, located within 1 m distance downstream a pyritic conglomerate rock, were significantly diverse. The glacier moraine surrounding the weathered site showed wide phylogenetic diversity and high evenness with 15 represented bacterial classes, dominated by Alphaproteobacteria and pioneer Cyanobacteria colonizers. The bioweathered area showed the lowest diversity indexes and only nine bacterial families, largely dominated by Acidobacteriaceae and Acetobacteraceae typical of acidic environments, in accordance with the low pH of the BSC. In the weathered BSC, iron-oxidizing bacteria were cultivated, with counts decreasing along with the increase of distance from the rock, and nutrient release from the rock was revealed by environmental scanning electron microscopy-energy dispersive X-ray analyses. The vegetated area showed the presence of Actinomycetales, Verrucomicrobiales, Gemmatimonadales, Burkholderiales, and Rhizobiales, denoting a bacterial community typical of developed soils and indicating that the lithoid substrate of the bare moraine was here subjected to an accelerated colonization, driven by iron-oxidizing activity.

  5. Source, transport and fate of soil organic matter inferred from microbial biomarker lipids on the East Siberian Arctic Shelf

    Science.gov (United States)

    Bischoff, Juliane; Sparkes, Robert B.; Doğrul Selver, Ayça; Spencer, Robert G. M.; Gustafsson, Örjan; Semiletov, Igor P.; Dudarev, Oleg V.; Wagner, Dirk; Rivkina, Elizaveta; van Dongen, Bart E.; Talbot, Helen M.

    2016-09-01

    The Siberian Arctic contains a globally significant pool of organic carbon (OC) vulnerable to enhanced warming and subsequent release by both fluvial and coastal erosion processes. However, the rate of release, its behaviour in the Arctic Ocean and vulnerability to remineralisation is poorly understood. Here we combine new measurements of microbial biohopanoids including adenosylhopane, a lipid associated with soil microbial communities, with published glycerol dialkyl glycerol tetraethers (GDGTs) and bulk δ13C measurements to improve knowledge of the fate of OC transported to the East Siberian Arctic Shelf (ESAS). The microbial hopanoid-based soil OC proxy R'soil ranges from 0.0 to 0.8 across the ESAS, with highest values nearshore and decreases offshore. Across the shelf R'soil displays a negative linear correlation with bulk δ13C measurements (r2 = -0.73, p = balance between delivery and removal of OC from different sources. The good correlation between the hopanoid and bulk terrestrial signal suggests a broad range of hopanoid sources, both fluvial and via coastal erosion, whilst GDGTs appear to be primarily sourced via fluvial transport. Analysis of ice complex deposits (ICDs) revealed an average R'soil of 0.5 for the Lena Delta, equivalent to that of the Buor-Khaya Bay sediments, whilst ICDs from further east showed higher values (0.6-0.85). Although R'soil correlates more closely with bulk OC than the BIT, our understanding of the endmembers of this system is clearly still incomplete, with variations between the different East Siberian Arctic regions potentially reflecting differences in environmental conditions (e.g. temperature, pH), but other physiological controls on microbial bacteriohopanepolyol (BHP) production under psychrophilic conditions are as yet unknown.

  6. Comparative Metagenomic Analysis Of Microbial Communities From Active Layer And Permafrost After Short-Term Thaw

    Science.gov (United States)

    Vishnivetskaya, T. A.; Chauhan, A.; Saarunya, G.; Murphy, J.; Williams, D.; Layton, A. C.; Pfiffner, S. M.; Stackhouse, B. T.; Sanders, R.; Lau, C. M.; myneni, S.; Phelps, T. J.; Fountain, A. G.; Onstott, T. C.

    2012-12-01

    .Permafrost areas occupy 20-25% of the Earth and extend of 1 km depths. The total number of prokaryotes and their biomass in cold regions are estimated to be 1 x 1030 cells and 140 x1015 g of C, respectively. Thus these environments serve as a reservoir of microbial and biogeochemical activity, which is likely to increase upon thawing. We are currently performing long-term thawing experiments at 4o C on 18, geochemically well-characterized, 1 meter long, intact cores consisting of active-layer (0-70 cm depth) and permafrost, collected from a 7 meter diameter ice-wedge polygon located at the McGill Arctic Research Station on Axel Heiberg Island, Nunavut, Canada. The organic carbon content of these cores averages ~1% at depth but increases to 5.4% in the top 10 cm. The cores were subdivided into four treatment groups: saturated cores (thawed while receiving artificial rain), drained cores (being thawed under natural hydrological conditions), dark cores (thawed under natural hydrological conditions with no light input) and control cores (maintain permafrost table at 70 cm depth). Over the course of 10 weeks the cores were progressively thawed from -4oC to 4oC from the top down to simulate spring thaw conditions in the Arctic. The temperatures at 5 cm, 35 cm, 65 cm, and below the permafrost table in the core were recorded continuously. Pore water and gas samples from 4 depths in each core were collected every two weeks and analyzed for pH, anions, cations, H2, CH4, CO, O2, N2, CO2 and δ13C of CO2. Headspace gas samples were collected weekly and analyzed for the same gases as the pore gases. Sediment sub-samples from the 4 depths were collected and total community genomic DNA (gDNA) was isolated using FastDNA SPIN kit followed by Qiagen column purification. The average yield of gDNA was ~3.5 μg/g of soil for the upper 5 cm active layers and decreased to ~1.5 μg/g of soil in the permafrost. The bacterial 16S copy numbers estimated by real-time quantitative PCR

  7. Survival of rapidly fluctuating natural low winter temperatures by High Arctic soil invertebrates.

    Science.gov (United States)

    Convey, Peter; Abbandonato, Holly; Bergan, Frode; Beumer, Larissa Teresa; Biersma, Elisabeth Machteld; Bråthen, Vegard Sandøy; D'Imperio, Ludovica; Jensen, Christina Kjellerup; Nilsen, Solveig; Paquin, Karolina; Stenkewitz, Ute; Svoen, Mildrid Elvik; Winkler, Judith; Müller, Eike; Coulson, Stephen James

    2015-12-01

    The extreme polar environment creates challenges for its resident invertebrate communities and the stress tolerance of some of these animals has been examined over many years. However, although it is well appreciated that standard air temperature records often fail to describe accurately conditions experienced at microhabitat level, few studies have explicitly set out to link field conditions experienced by natural multispecies communities with the more detailed laboratory ecophysiological studies of a small number of 'representative' species. This is particularly the case during winter, when snow cover may insulate terrestrial habitats from extreme air temperature fluctuations. Further, climate projections suggest large changes in precipitation will occur in the polar regions, with the greatest changes expected during the winter period and, hence, implications for the insulation of overwintering microhabitats. To assess survival of natural High Arctic soil invertebrate communities contained in soil and vegetation cores to natural winter temperature variations, the overwintering temperatures they experienced were manipulated by deploying cores in locations with varying snow accumulation: No Snow, Shallow Snow (30 cm) and Deep Snow (120 cm). Air temperatures during the winter period fluctuated frequently between +3 and -24 °C, and the No Snow soil temperatures reflected this variation closely, with the extreme minimum being slightly lower. Under 30 cm of snow, soil temperatures varied less and did not decrease below -12 °C. Those under deep snow were even more stable and did not decline below -2 °C. Despite these striking differences in winter thermal regimes, there were no clear differences in survival of the invertebrate fauna between treatments, including oribatid, prostigmatid and mesostigmatid mites, Araneae, Collembola, Nematocera larvae or Coleoptera. This indicates widespread tolerance, previously undocumented for the Araneae, Nematocera or Coleoptera, of

  8. Arctic hydrology and meteorology

    Energy Technology Data Exchange (ETDEWEB)

    Kane, D.L.

    1988-01-01

    The behavior of arctic ecosystems is directly related to the ongoing physical processes of heat and mass transfer. Furthermore, this system undergoes very large fluctuations in the surface energy balance. The buffering effect of both snow and the surface organic soils can be seen by looking at the surface and 40 cm soil temperatures. The active layer, that surface zone above the permafrost table, is either continually freezing or thawing. A large percentage of energy into and out of a watershed must pass through this thin veneer that we call the active layer. Likewise, most water entering and leaving the watershed does so through the active layer. To date, we have been very successful at monitoring the hydrology of Imnavait Creek with special emphasis on the active layer processes. The major contribution of this study is that year-round hydrologic data are being collected. An original objective of our study was to define how the thermal and moisture regimes within the active layer change during an annual cycle under natural conditions, and then to define how the regime will be impacted by some imposed terrain alteration. Our major analysis of the hydrologic data sets for Imnavait Creek have been water balance evaluations for plots during snowmelt, water balance for the watershed during both rainfall and snowmelt, and the application of a hydrologic model to predict the Imnavait Creek runoff events generated by both snowmelt and rainfall.

  9. 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.

  10. Biogeochemical modeling of CO2 and CH4 production in anoxic Arctic soil microcosms

    Science.gov (United States)

    Tang, Guoping; Zheng, Jianqiu; Xu, Xiaofeng; Yang, Ziming; Graham, David E.; Gu, Baohua; Painter, Scott L.; Thornton, Peter E.

    2016-09-01

    Soil organic carbon turnover to CO2 and CH4 is sensitive to soil redox potential and pH conditions. However, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximately describe the observed pH evolution without additional parameterization. Although Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. The equilibrium speciation predicts a substantial increase in CO2 solubility as pH increases, and taking into account CO2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO2 production from closed microcosms can be substantially underestimated based on headspace CO2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions.

  11. Soil formation in high elevation and permafrost areas in the Qinghai Plateau (China Edafogénesis en zonas elevadas y con permafrost en el Plateau Qunghai (China Formação do solo em áreas de elevada altitude e em ambientes"permafrost" do planalto de Qinghai Plateau (China

    Directory of Open Access Journals (Sweden)

    Joselito Arocena

    2012-07-01

    Full Text Available

    Soil systems continuously gain and lose matter and energy even in areas where climate is too harsh to support the higher plants such as in high elevations and in permafrost environments. The purpose of this paper was to elucidate soil formation at 4 700 m asl in the Kunlun Mountains of the Qinghai (Tibet Plateau, China. We collected twenty-six samples from three pedons developed on carbonate-rich slate and quartzitic-sandstone materials. The samples were analyzed for routine physical, chemical and mineralogical properties. Our results indicate that soil-forming processes are barely taking place in the study site as shown by pH > 7.0 reflecting limited decarbonation, biological activity (< 1.0% total C and < 0.05% total N, podzolization (<1 g Fep+Alp kg-1 soil and lessivage. The relative amounts of mica and kaolinite show no apparent change with depth suggesting minimal transformation and translocation of phyllosilicates. The most noticeable mineral transformation resulted in micaceous “flakes” and feldspathic “fragments” possibly due to thermal stress. Calcite is also observed coating the slate fragments. The soils are classified as Cryosols in the World Reference Base system and Gelisols in the Soil Taxonomy with ochric epipedon as the only diagnostic horizon indicating recent development of soils due to cold and arid environment. The results of this study show that soil-forming processes in harsh environments are manifested in the mechanical breakdown of minerals such as mica and feldspars.

    Los sistemas edáficos ganan y pierden continuamente materia y energía incluso en zonas donde el clima es demasiado severo como para permitir el desarrollo de plantas superiores, como son las zonas de elevada altitud o los ambientes con permafrost. El objetivo de este trabajo es analizar la formación del suelo a una altitud de 4 700 m en las Monta

  12. International Field School on Permafrost: Yenisei, Russian Federation - 2013

    Science.gov (United States)

    Nyland, K. E.; Streletskiy, D. A.; Grebenets, V. I.

    2013-12-01

    The International Field School on Permafrost was established in Russia as part of International Polar Year activities. The first course was offered in 2007 in Northwestern Siberia and attracted students from Russia, Germany, and the United States. Over the past seven years undergraduate and graduate students representing eight different countries in North America, Europe, and Asia have participated in the field school. This annual summer field course visits different regions of the Russian Arctic each year, but the three course foci remain consistent, which are to make in depth examinations of, 1) natural permafrost characteristics and conditions, 2) field techniques and applications, and 3) engineering practices and construction on permafrost. During these field courses students participate in excursions to local museums and exhibitions, meet with representatives from local administrations, mining and construction industries, and learn field techniques for complex permafrost investigations, including landscape and soil descriptions, temperature monitoring, active-layer measurements, cryostratigraphy, and more. During these courses students attend an evening lecture series by their professors and also give presentations on various regionally oriented topics of interest, such as the local geology, climate, or historical development of the region. This presentation will relate this summer's (July 2013) field course which took place in the Yenisei River region of central Siberia. The course took place along a bioclimatic transect from south to north along the Yenisei River and featured extended stays in the cities of Igarka and Noril'sk. This year's students (undergraduate, masters, and one PhD student) represented universities in the United States, Canada, and the Russian Federation. The organization of this course was accomplished through the cooperation of The George Washington University's Department of Geography and the Lomonosov Moscow State University

  13. Permafrost and periglacial research in Antarctica: New results and perspectives

    Science.gov (United States)

    Guglielmin, Mauro; Vieira, Gonçalo

    2014-11-01

    In the last two years the research within the Antarctic Permafrost, Periglacial Environments and Soils (ANTPAS) Expert Group of the Scientific Committee on Antarctic Research (SCAR) and Working Group of the International Permafrost Association (IPA) provided new results on the dynamics of periglacial environments both in Maritime and Continental Antarctica. In continental Antarctica despite the absence of air warming, in the last 15 years an active layer thickening and acceleration of permafrost degradation erosional phenomena were reported, these being mainly related to the increase of solar radiation. On the other hand, in Maritime Antarctica, with a dramatic air warming, permafrost degradation has been observed, but the role of snow cover on the ground energy balance and consequently on permafrost and active layer has been underlined. Moreover, many contributions on the knowledge on the characteristics of the Antarctic soils were carried out in several areas along a wide latitudinal range.

  14. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

    Energy Technology Data Exchange (ETDEWEB)

    Lipson, David A.; Raab, Theodore K.; Parker , Melanie; Kelley , Scott T.; Brislawn, Colin J.; Jansson, Janet K.

    2015-08-01

    Summary This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes,

  15. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

    Energy Technology Data Exchange (ETDEWEB)

    Lipson, David A.; Raab, Theodore K.; Parker , Melanie; Kelley , Scott T.; Brislawn, Colin J.; Jansson, Janet K.

    2015-07-21

    This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska, and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography, but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes, dominated by fermenters (Bacteroidetes and Firmicutes).

  16. Natural Radioactivity Accumulated in the Arctic from Long-range Atmospheric Transport - Observations in Canadian Monitoring Stations

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jing; Zhang, Weihua [Radiation Protection Bureau, Health Canada, 775 Brookfield Road, Ottawa K1A 1C1 (Canada)

    2014-07-01

    In the environment, the main sources of naturally occurring radionuclides come from radionuclides in the uranium decay series. Activity concentrations of uranium decay series radionuclides may vary considerably from place to place depending on the geological characteristics at the location. Their releases to the atmosphere are mainly through radon ({sup 222}Rn), a radioactive noble gas occurring naturally as an indirect decay product of uranium in soils and rocks. Due to the abundance of uranium, radon continuously emanates from continental land masses. With radon as the main source of naturally occurring radioactivity in the environment, one would think that the Arctic should be an area of low background radiation, because a considerable area of the Arctic is covered by glaciers and permafrost, and radon emanation rate has been reported to be negligible from those glacier and permafrost areas. However, available data have shown the opposite. The elevated level of naturally occurring radioactivity in the Arctic is due to natural sources outside of the Arctic, mainly through long-range atmospheric transport of radon and radon progeny. In some cases, natural radioactivity can accumulate to relatively high levels and become a health concern or a limiting factor of country food consumption. By definition, contaminants are undesirable substances which can cause harm to the environment, the biota, and humans. We can call these naturally accumulating radiological burdens to the Arctic 'natural contaminants' to distinguish them from the traditional meaning of contamination, the 'artificial contaminants' which are attributable to industrial or man-made sources. This paper reviews information available in the literature, analyses long-term atmospheric monitoring data in the Canadian high Arctic, sub-Arctic and mid-latitude sites, and provides discussion on research needed to address questions, such as how heavily the Arctic has been impacted by the

  17. Biodiversity of cryopegs in permafrost.

    Science.gov (United States)

    Gilichinsky, David; Rivkina, Elizaveta; Bakermans, Corien; Shcherbakova, Viktoria; Petrovskaya, Lada; Ozerskaya, Svetlana; Ivanushkina, Natalia; Kochkina, Galina; Laurinavichuis, Kyastus; Pecheritsina, Svetlana; Fattakhova, Rushania; Tiedje, James M

    2005-06-01

    This study describes the biodiversity of the indigenous microbial community in the sodium-chloride water brines (cryopegs) derived from ancient marine sediments and sandwiched within permafrost 100-120,000 years ago after the Arctic Ocean regression. Cryopegs remain liquid at the in situ temperature of -9 to -11 degrees C and make up the only habitat on the Earth that is characterized by permanently subzero temperatures, high salinity, and the absence of external influence during geological time. From these cryopegs, anaerobic and aerobic, spore-less and spore-forming, halotolerant and halophilic, psychrophilic and psychrotrophic bacteria, mycelial fungi and yeast were isolated and their activity was detected below 0 degrees C.

  18. Thermal State Of Permafrost In Urban Environment Under Changing Climatic Conditions

    Science.gov (United States)

    Streletskiy, D. A.; Grebenets, V. I.; Kerimov, A. G.; Kurchatova, A.; Andruschenko, F.; Gubanov, A.

    2015-12-01

    Risks and damage, caused by deformation of building and constructions in cryolithozone, are growing for decades. Worsening of cryo-ecological situation and loss of engineering-geocryological safety are induced by both technogenic influences on frozen basement and climate change. In such towns on permafrost as Vorkuta, Dixon more than 60% of objects are deformed, in Yakutsk, Igarka- nearly 40%, in Norilsk, Talnakh, Mirnij 35%, in old indigenous villages - approximately 100%; more than 80% ground dams with frozen cores are in poor condition. This situation is accompanied by activation of dangerous cryogenic processes. For example in growing seasonally-thaw layer is strengthening frost heave of pipeline foundation: only on Yamburg gas condensate field (Taz Peninsula) are damaged by frost heave and cut or completely replaced 3000 - 5000 foundations of gas pipelines. Intensity of negative effects strongly depends on regional geocryology, technogenic loads and climatic trends, and in Arctic we see a temperature rise - warming, which cause permafrost temperature rise and thaw). In built areas heat loads are more diverse: cold foundations (under the buildings with ventilated cellars or near termosyphons) are close to warm areas with technogenic beddings (mainly sandy), that accumulate heat, close to underground collectors for communications, growing thaw zones around, close to storages of snows, etc. Note that towns create specific microclimate with higher air temperature. So towns are powerful technogenic (basically, thermal) presses, placed on permafrost; in cooperation with climate changes (air temperature rise, increase of precipitation) they cause permafrost degradation. The analysis of dozens of urban thermal fields, formed in variable cryological and soil conditions, showed, that nearly 70% have warming trend, 20% - cooling and in 10% of cases the situation after construction is stable. Triggered by warming of climate changes of vegetation, depth and temperature of

  19. A permafrost glacial hypothesis – Permafrost carbon might help explaining the Pleistocene ice ages

    Directory of Open Access Journals (Sweden)

    Roland Zech

    2012-05-01

    Full Text Available Over the past several ~100 ka glacial-interglacial cycles, the concentration of atmospheric CO2 was closely coupled to global temperature, which indicates the importance of CO2 as a greenhouse gas. The reasons for changes in atmospheric CO2 have mainly been sought in the ocean, but remain elusive. Moreover, the mid-Pleistocene transition from the ‘41 ka world’ during the early Pleistocene before ~0.7 Ma to the ~100 ka ice age cycles is poorly understood. The classical Milankovitch theory of summer insolation forcing at high northern latitudes can not fully explain the Pleistocene ice age rhythm. Based on the recent findings that the amount of soil organic carbon stored in high-latitude permafrost regions has been greatly underestimated and the simple logic that permafrost regions and respective carbon pools were likely much larger during glacials than during interglacials, a ‘permafrost glacial hypothesis’ is proposed: (i Gradual sequestration of CO2 in permafrost soils during coolings and rapid release of CO2 and methane during terminations, respectively, provide important positive feedbacks for the climate. (ii Integrated annual insolation at the southern and thus most sensitive permafrost boundary may act as a trigger for global climate changes. (iii The mid-Pleistocene transition might be readily explained with permafrost extents reaching ~45°N during the long-term Pleistocene cooling, resulting in a transition from high-latitude obliquity (~41 ka to mid-latitude eccentricity (~100 ka forcing.

  20. Can Plant Community Turnover Mitigate Permafrost Thaw Feedbacks to the Climate System?

    Science.gov (United States)

    Hough, M.; Garnello, A.; Finnell, D.; Palace, M. W.; Rich, V. I.; Saleska, S. R.

    2014-12-01

    In many parts of the Arctic, permafrost thaw due to rising temperatures results in the conversion of dry tundra to wetland bog and fen ecosystems. Such increases in anaerobic environments may have substantial feedbacks to the rate of climate change through the increased production of CH4, a greenhouse gas an order of magnitude more potent than the CO2 respired from aerobic soils. However, the total emission rates of CH4 and CO2 alone cannot predict the magnitude of feedback to the climate system since this will also depend on the ecosystem's overall carbon balance and the source of carbon (new vs old) producing the emissions. Thus, building detailed carbon budgets is essential to understanding the potential climate feedbacks of habitat changes due to permafrost thaw. We studied above-ground plant biomass and its carbon content in order to calculate the inputs of new carbon to the soil along a permafrost thaw gradient with previously well-quantified CO2 and CH4 fluxes in northern Sweden. In order to account for within-season plant community turnover, we monitored plant percent cover over the course of a growing season in three communities: areas underlain by permafrost dominated by E. vaginatum, and E. nigrum, recently thawed sphagnum dominated areas, and more established E. angustifolium dominated fen communities. Additionally, we calculated end of season biomass and percent carbon for each species and compared our findings to previously published community composition assessments from 1972/1973 and 2000. We tied our ground-based measurements to aerial remote sensing images to extrapolate biomass and percent carbon across the mire based on community type. These results allow us to calculate total carbon inputs to the mire from new above-ground biomass. By coupling these measurements with flux rates from each habitat we will be able to assess the degree to which increased biomass production might offset the increase in CH4 released from soils as a result of plant

  1. Impact of permafrost degradation on embankment deformation of Qinghai-Tibet Highway in permafrost regions

    Institute of Scientific and Technical Information of China (English)

    彭惠; 马巍; 穆彦虎; 金龙

    2015-01-01

    Based on long-term monitoring data, the relationships between permafrost degradation and embankment deformation are analyzed along the Qinghai−Tibet Highway (QTH). Due to heat absorbing effect of asphalt pavement and climate warming, permafrost beneath asphalt pavement experienced significant warming and degradation. During the monitoring period, warming amplitude of the soil at depth of 5 m under asphalt ranged from 0.21 °C at the XD1 site to 0.5 °C at the KL1 site. And at depth of 10 m, the increase amplitude of ground temperature ranged from 0.47 °C at the NA1 site to 0.07 °C at the XD1 site. Along with ground temperature increase, permafrost table beneath asphalt pavement decline considerably. Amplitude of permafrost table decline varied from 0.53 m at the KL1 site to 3.51 m at the NA1 site, with mean amplitude of 1.65 m for 8 monitoring sites during the monitoring period. Due to permafrost warming and degradation, the embankment deformation all performed as settlement at these sites. At present, those settlements still develop quickly and are expected to continue to increase in the future. The embankment deformations can be divided into homogeneous deformation and inhomogeneous deformation. Embankment longitudinal inhomogeneous deformation causes the wave deformations and has adverse effects on driving comfort and safety, while lateral inhomogeneous deformation causes longitudinal cracks and has an adverse effect on stability. Corresponding with permafrost degradation processes, embankment settlement can be divided into four stages. For QTH, embankment settlement is mainly comprised of thawing consolidation of ice-rich permafrost and creep of warming permafrost beneath permafrost table.

  2. Movement of trichloroethene in a discontinuous permafrost zone.

    Science.gov (United States)

    Carlson, Andrea E; Barnes, David L

    2011-06-01

    At a site with discontinuous permafrost in Fairbanks, Alaska, releases of trichloroethene (TCE), an industrial solvent, have caused contamination of the groundwater. The objective of this study was to investigate the relationship between the migration pathway of the TCE groundwater plume and the distribution of the discontinuous permafrost at the site. The TCE plume configuration is substantially different than what regional hydrology trends would predict. Using GIS, we conducted a geostatistical analysis of field data collected during soil-boring installations and groundwater monitoring well sampling. With the analysis results, we constructed maps of the permafrost-table elevation (top of permafrost) and of the groundwater gradients and TCE concentrations from multiyear groundwater sampling events. The plume concentrations and groundwater gradients were overlain on the permafrost map to correlate permafrost locations with groundwater movement and the spatial distribution of TCE moving with groundwater. Correlation of the overlay maps revealed converging and diverging groundwater flow in response to the permafrost-table distribution, the absence of groundwater contamination in areas with a high permafrost-table elevation, and channeling of contaminants and water between areas of permafrost. In addition, we measured groundwater elevations in nested wells to quantify vertical gradients affecting TCE migration. At one set of nested wells down gradient from an area of permafrost we measured an upward vertical gradient indicating recharge of groundwater from the subpermafrost region of the aquifer causing dilution of the plume. The study indicates that the variable distribution of the permafrost is affecting the way groundwater and TCE move through the aquifer. Consequently, changes to the permafrost configuration due to thawing would likely affect both groundwater movement and TCE migration, and areas that were contaminant-free may become susceptible to contamination.

  3. Global Policy Implications of Thawing Permafrost

    Science.gov (United States)

    Schaefer, K. M.; Zhang, T.; Bruhwiler, L.; Barrett, A. P.; Li, Z.

    2011-12-01

    Global treaties to reduce fossil fuel emissions should include a 15% allocation for permafrost carbon emissions or we will overshoot our target CO2 concentration and end up with a warmer climate than planned. Arctic permafrost currently contains 1466 Gt of carbon frozen since the last ice age, roughly double the amount of carbon in the atmosphere. We estimate 190±64 Gt of this carbon will thaw out, decay, and end up in the atmosphere by 2300, potentially increasing atmospheric CO2 concentrations by 87±29 ppm. A carbon release of this magnitude is equal to 15% of the total allowed emissions to hit a target CO2 concentration of 700 ppm. Global targets for fossil fuel emissions must be reduced an additional 15% to account for the release of carbon from thawing permafrost. Current treaty negotiations do not include a 15% allocation for permafrost carbon emissions. We present the scientific basis for our results and summarize our successes and failures in trying to influence international treaty negotiations to reduce fossil fuel emissions.

  4. Diversity of soil organisms in alpine and arctic soils in Europe. Review an research needs

    Directory of Open Access Journals (Sweden)

    Broll, Gabrielle

    1998-12-01

    Full Text Available The diversity of soil organisms and soil ecological processes in different mountain regions of Europe are reviewed. Detailed taxonomic studies on soil organisms have been made in the Alps and in Northern Europe since the end of the last century, however, there is a paucity of data from Southern Europe. Future studies could include the re-sampling of historic study sites to assess if there has been a change in the soil fauna and microorganisms. The role of key abiotic processes such as cryoturbation should be quantified and further research should focus on identifying indicator organisms, keystone species and functional groups. In addition, studies on soil organic matter and particularly on humus forms, the products of soil ecological processes should be encouraged. Ecotones, where the influence of spatial heterogeneity on soil biodiversity is likely to be particularly pronounced, appear to be the most rewarding for such studies.

    [fr] La diversité des organismes du sol et les différents processus écologiques ayant lié dans les diverses régions de montagne en Europe sont détaillés. Des études approfondies sur la taxonomie des organismes du sol ont été développées dans les Alpes et en Europe du Nord depuis la fin du siècle dernier, mais par contre il y a peu de données sur l'Europe du Sud. Dans l'avenir on pourrait re-étudier les sites bien connus de façon à savoir s'il y a eu de changements dans la faune et les microorganismes du sol. Il faudrait quantifier le rôle des processus abiotiques comme la cryoturbation, identifier les organismes indicateurs, les espèces-clé et les groupes fonctionnels. Il est aussi indispensable de développer les études sur la matière organique et en particulier les types d'humus, en tant que résultat des processus écologiques du sol. Les ecotones, dans lesquels l'influence de l’heterogeneité spatiale sur la biodiversité du sol est particulièrement prononcée, semblent les plus

  5. Above- and belowground responses of Arctic tundra ecosystems to altered soil nutrients and mammalian herbivory.

    Science.gov (United States)

    Gough, Laura; Moore, John C; Shaver, Gauis R; Simpson, Rodney T; Johnson, David R

    2012-07-01

    Theory and observation indicate that changes in the rate of primary production can alter the balance between the bottom-up influences of plants and resources and the top-down regulation of herbivores and predators on ecosystem structure and function. The exploitation ecosystem hypothesis (EEH) posited that as aboveground net primary productivity (ANPP) increases, the additional biomass should support higher trophic levels. We developed an extension of EEH to include the impacts of increases in ANPP on belowground consumers in a similar manner as aboveground, but indirectly through changes in the allocation of photosynthate to roots. We tested our predictions for plants aboveground and for phytophagous nematodes and their predators belowground in two common arctic tundra plant communities subjected to 11 years of increased soil nutrient availability and/or exclusion of mammalian herbivores. The less productive dry heath (DH) community met the predictions of EEH aboveground, with the greatest ANPP and plant biomass in the fertilized plots protected from herbivory. A palatable grass increased in fertilized plots while dwarf evergreen shrubs and lichens declined. Belowground, phytophagous nematodes also responded as predicted, achieving greater biomass in the higher ANPP plots, whereas predator biomass tended to be lower in those same plots (although not significantly). In the higher productivity moist acidic tussock (MAT) community, aboveground responses were quite different. Herbivores stimulated ANPP and biomass in both ambient and enriched soil nutrient plots; maximum ANPP occurred in fertilized plots exposed to herbivory. Fertilized plots became dominated by dwarf birch (a deciduous shrub) and cloudberry (a perennial forb); under ambient conditions these two species coexist with sedges, evergreen dwarf shrubs, and Sphagnum mosses. Phytophagous nematodes did not respond significantly to changes in ANPP, although predator biomass was greatest in control plots. The

  6. 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

    Circumpolar permafrost soils store about half of the global soil organic carbon pool. These huge amounts of organic matter (OM) could accumulate due to low temperatures and water saturated soil conditions over the course of millennia. Currently most of this OM remains frozen and therefore does not take part in the active carbon cycle, making permafrost soils a globally important carbon sink. Over the last decades mean annual air temperatures in the Arctic increased stronger than the global mean and this trend is projected to continue. As a result the permafrost carbon pool is under climate pressure possibly creating a positive climate feedback due to the thaw-induced release of greenhouse gases to the atmosphere. Arctic warming will lead to increased annual permafrost thaw depths and Arctic river runoff likely resulting in enhanced mobilization and export of old, previously frozen soil-derived OM. Consequently, the great arctic rivers play an important role in global biogeochemical cycles by connecting the large permafrost carbon pool of their hinterlands with the arctic shelf seas and the Arctic Ocean. The first part of this thesis deals with particulate organic matter (POM) from the Lena Delta and adjacent Buor Khaya Bay. The Lena River in central Siberia is one of the major pathways translocating terrestrial OM from its southernmost reaches near Lake Baikal to the coastal zone of the Laptev Sea. The permafrost soils from the Lena catchment area store huge amounts of pre-aged OM, which is expected to be remobilized due to climate warming. To characterize the composition and vegetation sources of OM discharged by the Lena River, the lignin phenol and carbon isotopic composition (δ{sup 13}C and Δ{sup 14}C) in total suspended matter (TSM) from surface waters, surface sediments from the Buor Khaya Bay along with soils from the Lena Delta's first (Holocene) and third terraces (Pleistocene ice complex) were analyzed. The lignin compositions of these samples are

  7. Assessment of permafrost distribution maps in the Hindu Kush Himalayan region using rock glaciers mapped in Google Earth

    Science.gov (United States)

    Schmid, M.-O.; Baral, P.; Gruber, S.; Shahi, S.; Shrestha, T.; Stumm, D.; Wester, P.

    2015-11-01

    The extent and distribution of permafrost in the mountainous parts of the Hindu Kush Himalayan (HKH) region are largely unknown. A long tradition of permafrost research, predominantly on rather gentle relief, exists only on the Tibetan Plateau. Two permafrost maps are available digitally that cover the HKH and provide estimates of permafrost extent, i.e., the areal proportion of permafrost: the manually delineated Circum-Arctic Map of Permafrost and Ground Ice Conditions (Brown et al., 1998) and the Global Permafrost Zonation Index, based on a computer model (Gruber, 2012). This article provides a first-order assessment of these permafrost maps in the HKH region based on the mapping of rock glaciers. Rock glaciers were used as a proxy, because they are visual indicators of permafrost, can occur near the lowermost regional occurrence of permafrost in mountains, and can be delineated based on high-resolution remote sensing imagery freely available on Google Earth. For the mapping, 4000 square samples (~ 30 km2) were randomly distributed over the HKH region. Every sample was investigated and rock glaciers were mapped by two independent researchers following precise mapping instructions. Samples with insufficient image quality were recorded but not mapped. We use the mapping of rock glaciers in Google Earth as first-order evidence for permafrost in mountain areas with severely limited ground truth. The minimum elevation of rock glaciers varies between 3500 and 5500 m a.s.l. within the region. The Circum-Arctic Map of Permafrost and Ground Ice Conditions does not reproduce mapped conditions in the HKH region adequately, whereas the Global Permafrost Zonation Index does so with more success. Based on this study, the Permafrost Zonation Index is inferred to be a reasonable first-order prediction of permafrost in the HKH. In the central part of the region a considerable deviation exists that needs further investigations.

  8. Impact of interactive vegetation phenology on the simulated pan-Arctic land surface state

    Science.gov (United States)

    Teufel, Bernardo; Sushama, Laxmi

    2016-04-01

    The pan-Arctic land surface is undergoing rapid changes in a warming climate, with near-surface permafrost projected to degrade significantly during the 21st century. This can have important impacts on the regional climate and hydrology through various feedbacks, including vegetation-related feedbacks. In this study, the impact of interactive phenology on the land surface state, including near-surface permafrost, is assessed by comparing two simulations of the Canadian Land Surface Scheme (CLASS) - one with interactive phenology, modelled using the Canadian Terrestrial Ecosystem Model (CTEM), and the other with prescribed phenology. These simulations are performed for the 1979-2012 period, using atmospheric forcing from ECMWF's ERA-Interim reanalysis. The impact of interactive phenology on projected changes to the land surface state are also assessed by comparing two simulations of CLASS (with and without interactive phenology), spanning the 1961-2100 period, driven by atmospheric forcing 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 with available observational estimates of plant area index, primary productivity, spatial distribution of permafrost and active layer thickness suggests that the model captures reasonably well the general distribution of vegetation and permafrost. Significant differences in evapotranspiration, leading to differences in runoff, soil temperature and active layer thickness are noted when comparing CLASS simulations with and without interactive phenology. Furthermore, the CLASS simulations with and without interactive phenology for RCP8.5 show extensive near-surface permafrost degradation by the end of the 21st century, with slightly accelerated degradation of permafrost in the simulation with interactive phenology, pointing towards a positive feedback of changes in

  9. Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes

    Directory of Open Access Journals (Sweden)

    A. Ekici

    2014-09-01

    Full Text Available Modelling soil thermal dynamics at high latitudes and altitudes requires representations of specific physical processes such as snow insulation, soil freezing/thawing, as well as subsurface conditions like soil water/ice content and soil texture type. We have compared six different land models (JSBACH, ORCHIDEE, JULES, COUP, HYBRID8, LPJ-GUESS at four different sites with distinct cold region landscape types (i.e. Schilthorn-Alpine, Bayelva-high Arctic, Samoylov-wet polygonal tundra, Nuuk-non permafrost Arctic to quantify the importance of physical processes in capturing observed temperature dynamics in soils. This work shows how a range of models can represent distinct soil temperature regimes in permafrost and non-permafrost soils. Snow insulation is of major importance for estimating topsoil conditions and must be combined with accurate subsoil temperature dynamics to correctly estimate active layer thicknesses. Analyses show that land models need more realistic surface processes (such as detailed snow dynamics and moss cover with changing thickness/wetness as well as better representations of subsoil thermal dynamics (i.e. soil heat transfer mechanism and correct parameterization of heat conductivity/capacities.

  10. Site- and horizon-specific patterns of microbial community structure and enzyme activities in permafrost-affected soils of Greenland

    DEFF Research Database (Denmark)

    Gittel, Antje; Barta, Jiri; Kohoutova, Iva;

    2014-01-01

    that the distribution pattern of Actinobacteria and a variety of other bacterial classes was related to the activity of phenol oxidases and peroxidases supporting the hypothesis that bacteria might resume the role of fungi in oxidative enzyme production and degradation of phenolic and other complex substrates...... on its impact on the carbon budget are thus still highly uncertain. However, the fate of OC is not only determined by abiotic factors, but closely tied to microbial activity. We investigated eight soil profiles in northeast Greenland comprising two sites with typical tundra vegetation and one wet fen...

  11. Climate-sensitive subsea permafrost and related gas expulsions on the South Kara Sea shelf. Field studies and modeling results.

    Science.gov (United States)

    Portnov, Alexey; Mienert, Jurgen; Serov, Pavel

    2015-04-01

    Thawing subsea permafrost controls methane release bearing a considerable impact on the climate-sensitive Arctic environment. Significant expulsion of methane into shallow Russian shelf areas may continue to rise into the atmosphere on the Arctic shelves in response to intense degradation of relict subsea permafrost. The release of formerly trapped gas, essentially methane, is linked to the permafrost evolution. Modeling of the permafrost at the West Yamal shelf allowed describing its evolution from the Late Pleistocene to Holocene. During the previous work we detected extensive emissions of free gas into the water column at the boundary between today's shallow water permafrost and deeper water non-permafrost areas. These gas expulsions formed seismic and hydro-acoustic anomalies on the high-resolution seismic records. We supposed that in the water depths modeling results of relict permafrost distributions with these field data from the South Kara Sea. Modeling results suggest a highly-dynamic permafrost system that directly responds to even minor variations of lower and upper boundary conditions, e.g. heat flux from below and/or bottom water temperature changes from above. We present several scenarios of permafrost evolution and show that potentially minimal modern extent of the permafrost at the West Yamal shelf is limited by ~17 m isobaths, whereas maximal probable extent coincides with ~100 m isobaths. The model also predicts seaward tapering of relict permafrost with its maximal thickness 275-390 m near the shore line. We also present sensitivity analysis which define the wider range of modeling results depending on the changing input parameters (e.g. geothermal heat flux, bottom water temperature, porosity of the sediments). The model adapts well to corresponding field data, providing crucial information about the modern permafrost conditions, current location of the upper and lower permafrost boundaries and its possible impact on both the hydrosphere and

  12. Simulations of permafrost evolution at Olkiluoto

    Energy Technology Data Exchange (ETDEWEB)

    Hartikainen, J. [Aalto Univ., Espoo (Finland)

    2013-07-15

    This report provides numerical estimations of the evolution of permafrost and perennially frozen ground at Olkiluoto on time-scales of 60,000 and 125,000 years using Olkiluoto's site-specific information on time histories of ground level temperatures, ice sheet thickness, basal conditions, shoreline migration, soil and vegetation cover as well as heat generation from the spent fuel at a depth of 420 metres. When considering environmental conditions akin to the last glacial cycle for a 125,000 years long period, the maximum permafrost depth over the repository area can exceed the depth of 300 m and the maximum depth of perennially frozen ground the depth of 270 m. If Olkiluoto, after a 50,000 years long temperate phase of boreal climate, was subjected to a 10,000 years long periglacial period with air temperature decreased between -5 deg C and -10 deg C, the maximum permafrost depth would range between 60 and 240 m and the maximum depth of perennially frozen ground between 50 and 220 m. Furthermore, permafrost would reach the repository depth in 10,000 years, if the air temperature was lowered down to -15 deg C and the ground surface had a very thin vegetation and snow cover. Alternatively, if Olkiluoto experienced a 125,000 years long glacial cycle with a very long periglacial periods of low air temperatures and thin vegetation and snow cover and without any ice sheet development, permafrost would reach the depth of 400 m in 98,000 years and perennially frozen ground in 101,000 years. The areal distribution of permafrost and perennially frozen ground are broadly affected by the snow cover, lakes and the peat areas, especially when an extensive peat growth occurs. The lack of snow cover can enhance the evolution of the maximum depth of permafrost and perennially frozen ground by over 50 %. In addition, ground thermal conditions and the heat generation from the spent fuel modify the spatial and temporal development of permafrost and perennially frozen ground. A

  13. CMIP5 permafrost degradation projection:A comparison among different regions

    Science.gov (United States)

    Guo, Donglin; Wang, Huijun

    2016-05-01

    concentration pathway (RCP)4.5, permafrost retreats toward the Arctic, and the thaw in every region mainly occurs at the southern edge of the permafrost area. Under RCP8.5, almost no permafrost is expected to remain in China, the United States, and the Tibetan Plateau. Permafrost in Russia will remain mainly in the western part of the east Siberian Mountains, and permafrost in Canada will retreat to the north of 65°N. Possible uncertainties in this study are primarily attributed to the climate model's coarse horizontal resolution. The results of the present study will be useful for understanding future permafrost degradation from the regional perspective.

  14. Isotopic insights into methane production, oxidation, and emissions in Arctic polygon tundra.

    Science.gov (United States)

    Vaughn, Lydia J S; Conrad, Mark E; Bill, Markus; Torn, Margaret S

    2016-10-01

    Arctic wetlands are currently net sources of atmospheric CH4 . Due to their complex biogeochemical controls and high spatial and temporal variability, current net CH4 emissions and gross CH4 processes have been difficult to quantify, and their predicted responses to climate change remain uncertain. We investigated CH4 production, oxidation, and surface emissions in Arctic polygon tundra, across a wet-to-dry permafrost degradation gradient from low-centered (intact) to flat- and high-centered (degraded) polygons. From 3 microtopographic positions (polygon centers, rims, and troughs) along the permafrost degradation gradient, we measured surface CH4 and CO2 fluxes, concentrations and stable isotope compositions of CH4 and DIC at three depths in the soil, and soil moisture and temperature. More degraded sites had lower CH4 emissions, a different primary methanogenic pathway, and greater CH4 oxidation than did intact permafrost sites, to a greater degree than soil moisture or temperature could explain. Surface CH4 flux decreased from 64 nmol m(-2)  s(-1) in intact polygons to 7 nmol m(-2)  s(-1) in degraded polygons, and stable isotope signatures of CH4 and DIC showed that acetate cleavage dominated CH4 production in low-centered polygons, while CO2 reduction was the primary pathway in degraded polygons. We see evidence that differences in water flow and vegetation between intact and degraded polygons contributed to these observations. In contrast to many previous studies, these findings document a mechanism whereby permafrost degradation can lead to local decreases in tundra CH4 emissions.

  15. Subsea Permafrost Climate Modeling - Challenges and First Results

    Science.gov (United States)

    Rodehacke, C. B.; Stendel, M.; Marchenko, S. S.; Christensen, J. H.; Romanovsky, V. E.; Nicolsky, D.

    2015-12-01

    Recent observations indicate that the East Siberian Arctic Shelf (ESAS) releases methane, which stems from shallow hydrate seabed reservoirs. The total amount of carbon within the ESAS is so large that release of only a small fraction, for example via taliks, which are columns of unfrozen sediment within the permafrost, could impact distinctly the global climate. Therefore it is crucial to simulate the future fate of ESAS' subsea permafrost with regard to changing atmospheric and oceanic conditions. However only very few attempts to address the vulnerability of subsea permafrost have been made, instead most studies have focused on the evolution of permafrost since the Late Pleistocene ocean transgression, approximately 14000 years ago.In contrast to land permafrost modeling, any attempt to model the future fate of subsea permafrost needs to consider several additional factors, in particular the dependence of freezing temperature on water depth and salt content and the differences in ground heat flux depending on the seabed properties. Also the amount of unfrozen water in the sediment needs to be taken into account. Using a system of coupled ocean, atmosphere and permafrost models will allow us to capture the complexity of the different parts of the system and evaluate the relative importance of different processes. Here we present the first results of a novel approach by means of dedicated permafrost model simulations. These have been driven by conditions of the Laptev Sea region in East Siberia. By exploiting the ensemble approach, we will show how uncertainties in boundary conditions and applied forcing scenarios control the future fate of the sub sea permafrost.

  16. 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

    landscapes, and defining permafrost research priorities - a roadmap for the future. The latter project is a joint effort with the Climate and Cryosphere initiative (CliC) and a contribution to the upcoming International Conference on Arctic Research Planning III (ICARP III). The product stemming from the effort will consist of a journal publication listing permafrost research priorities and putting them into context. In all of these activities, the IPA emphasizes the involvement of young researchers (especially through the Permafrost Young Researchers Network and APECS) as well as its collaboration with international partner organizations such as IASC, SCAR, CliC, IACS, IUGS and WMO.

  17. Permafrost-associated gas hydrate: is it really approximately 1% of the global system?

    Science.gov (United States)

    Ruppel, Carolyn

    2015-01-01

    Permafrost-associated gas hydrates are often assumed to contain ∼1 % of the global gas-in-place in gas hydrates based on a study26 published over three decades ago. As knowledge of permafrost-associated gas hydrates has grown, it has become clear that many permafrost-associated gas hydrates are inextricably linked to an associated conventional petroleum system, and that their formation history (trapping of migrated gas in situ during Pleistocene cooling) is consistent with having been sourced at least partially in nearby thermogenic gas deposits. Using modern data sets that constrain the distribution of continuous permafrost onshore5 and subsea permafrost on circum-Arctic Ocean continental shelves offshore and that estimate undiscovered conventional gas within arctic assessment units,16 the done here reveals where permafrost-associated gas hydrates are most likely to occur, concluding that Arctic Alaska and the West Siberian Basin are the best prospects. A conservative estimate is that 20 Gt C (2.7·1013 kg CH4) may be sequestered in permafrost-associated gas hydrates if methane were the only hydrate-former. This value is slightly more than 1 % of modern estimates (corresponding to 1600 Gt C to 1800 Gt C2,22) for global gas-in-place in methane hydrates and about double the absolute estimate (11.2 Gt C) made in 1981.26

  18. Morphology and physical properties of soil material in cryogenic cracks of permafrost-affected meadow-chernozemic soils of the Trans-Baikal Region

    Science.gov (United States)

    Tsybenov, Yu. B.; Chimitdorzhieva, G. D.; Chimitdorzhieva, E. O.; Egorova, R. A.; Mil'kheev, E. Yu.; Davydova, T. V.; Korsunova, Ts. D.-Ts.

    2016-08-01

    Meadow-chernozemic soils (Turbic Chernozems Molliglossic) in the western Trans-Baikal Region are dissected by large cryogenic cracks penetrating to the depth of 100-120 cm and filled with humified material. The depth of humus pockets is 50-80 cm, and their width in the upper part is 50-90 cm. The lower boundary of most of the humus pockets lies at the depth of 60-70 cm. The development of cryogenic cracks proceeded due to their penetration into the frozen ground, which is evidenced by their sharply narrowing lower part. The fraction of physical clay (humus content in this material. The contents of humus and adsorbed bases sharply decrease down through the soil profile in the soil mass between the cracks and remain relatively stable in the material filling the cracks. The soil mass in humus pockets is less compact that that in the background soil mass at the same depth, which is explained by the higher humus content in the pockets. Humified soil material in the pockets is also characterized by a higher porosity and, hence, higher water permeability than the surrounding soil mass.

  19. Assessment of permafrost distribution maps in the Hindu Kush-Himalayan region using rock glaciers mapped in Google Earth

    Science.gov (United States)

    Schmid, M.-O.; Baral, P.; Gruber, S.; Shahi, S.; Shrestha, T.; Stumm, D.; Wester, P.

    2014-10-01

    The extent and distribution of permafrost in the mountainous parts of the Hindu Kush-Himalayan (HKH) region have barely been investigated and are largely unknown. Only on the Tibetan Plateau a long tradition of permafrost research on rather gentle relief exists. Two permafrost maps are available that cover the HKH and provide estimates of permafrost extent, i.e. the areal proportion of permafrost: the manually delineated Circum-Arctic Map of Permafrost and Ground Ice Conditions (Brown et al., 1998) and the Global Permafrost Zonation Index, based on a computer model (Gruber, 2012). This article provides first-order assessment of permafrost maps of the HKH region based on the mapping of rock glaciers. Rock glaciers were used as a proxy, because they are visual indicators of permafrost, often occurring near the lowermost regional occurrence of permafrost in mountains, and because they can be delineated based on high-resolution remote sensing imagery freely available on Google Earth. For the mapping 4000 square samples (approx. 30 km2) were randomly distributed over the HKH region. Every sample was investigated and rock glaciers were mapped by two independent researchers following precise mapping instructions. Samples with insufficient image quality were recorded but not mapped. It is shown that mapping of rock glaciers in Google Earth can be used as first-order evidence for permafrost in mountain areas with severely limited ground truth. The minimum elevation of rock glaciers varies between 3500 and 5500 m a.s.l. within the region. The Circum-Arctic Map of Permafrost and Ground Ice Conditions does not reproduce mapped conditions in the HKH region adequately, whereas the Global Permafrost Zonation Index appears to be a reasonable first-order prediction of permafrost in the HKH. Only in the central part of the region a considerable deviation exists that needs further investigations.

  20. The Role of Disturbance in Arctic Ecosystem Response to a Changing Climate

    Science.gov (United States)

    Hinzman, L. D.

    2014-12-01

    Wildfires in the tundra regions and the boreal forest project an immediate effect upon the surface energy and water budget by drastically altering the surface albedo, roughness, infiltration rates, and moisture absorption capacity in organic soils. Although fires create a sudden and drastic change to the landcover, it is only the beginning of a long process of recovery and perhaps a shift to a different successional pathway. In permafrost regions, these effects become part of a process of long-term (20-50 years) cumulative impacts. Burn severity may largely determine immediate impacts and long-term disturbance trajectories. As transpiration decreases or ceases, soil moisture increases markedly, remaining quite wet throughout the year. Because the insulating quality of the organic layer is removed during fires, permafrost begins to thaw near the surface and warm to greater depths. Within a few years, it may thaw to the point where it can no longer completely refreeze every winter, creating a permanently thawed layer in the soil called a talik. After formation of a talik, soils can drain internally throughout the year. At this point, soils may become quite dry, as the total precipitation received annually in the Arctic is quite low. The local ecological community must continuously adapt to the changing soil thermal and moisture regimes. The wet soils found over shallow permafrost favor black spruce forests. After a fire creates a deeper permafrost table (thicker active layer) the invading tree species tend to be birch or alder. The hydrologic and thermal regime of the soil is the primary factor controlling these vegetation trajectories and the subsequent changes in surface mass and energy fluxes. The complexities of a changing climate accentuate these processes of change and complicate predictions of the resulting vegetation trajectories. Understanding these shifts in vegetative communities and quantifying the consequences of thawing permafrost can only be

  1. Accumulation of carbon and nitrogen in vegetation and soils of deglaciated area in Ellesmere Island, high-Arctic Canada

    Science.gov (United States)

    Osono, Takashi; Mori, Akira S.; Uchida, Masaki; Kanda, Hiroshi

    2016-09-01

    The amount of biomass, carbon (C), and nitrogen (N) in vegetation and soil were measured at two spatial scales in the high Arctic. At the scale of proglacial landscape, the amount of C and N in aboveground and belowground parts of vegetation, surface litter, and soil were significantly affected by the habitat (moraines vs hummocks), the relative age of the terrain after the deglaciation, and/or the vegetation. At another scale, we focused on mudboils as an agent of local disturbance in the vegetation and soil of the glacier foreland. The biomass and the amount of C and N in aboveground vegetation, surface litter, biological soil crust, and soil were generally increased with the stage of mudboils' inactivation. Biomass, C, and N in aboveground vegetation and surface litter were generally greater at moraine than at hummock, whereas those in biological soil crust and soil were greater at hummock. Principal component analysis identified two pathways, xeric and mesic ones on moraines and hummocks, respectively, of C and N accumulation both at the two spatial scales. These results suggested that the C and N accumulation was not linearly related to the time since deglaciation and that moisture condition, vegetation, and mudboil activity were locally important.

  2. Great challenges of and innovative solutions to the unstable permafrost in Central and High Asia under a warming climate-the first Asian Conference on Permafrost

    Institute of Scientific and Technical Information of China (English)

    Huijun Jin; Jerry Brown

    2007-01-01

    @@ The first Asian Conference on Permafrost (ACOP) was co-sponsored by the State Key Laboratory of Frozen Soils Engineering(SKLFSE) of the Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI), the Geographical Society of China (GSA), and the Intema-tional Permafrost Association (IPA), and cochaired by Academician Guodong Cheng,President of the Chinese Academy of Sci-ences Lanzhou Branch, and Professor Jerry Brown, President, International Permafrost Association.

  3. Climatic change and permafrost. Record from surficial deposits

    Science.gov (United States)

    Carter, L. David

    1990-01-01

    The physical and chemical characteristics of surficial deposits and the floral and faunal remains they contain provide information that is useful for interpreting both paleoclimatic and past permafrost conditions. Surficial deposits thus provide a record of climatic change and permafrost history. This record suggests that initiation of permafrost in lowland areas of the Southern Arctic Archipelago and continents of the northern hemisphere may have occurred about 2,400,000 years ago during the pronounced cooling that led to the first major glaciation of late Cenozoic time. Since then, climate has been relatively cold but cyclically variable, characterized by the growth and shrinkage of large, continental ice sheets. Permafrost has expanded and contracted in response to these climatic changes, and we can expect the present permafrost conditions to change in response to future climatic changes. To predict the response of permafrost and the landscape to future climatic change we should: (1) Define relations between climate and the modern landscape; (2) establish long-term records of past climatic change and landscape response; and (3) determine the paleoenvironments of past warm periods as possible analogs for future global warming.

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

    Science.gov (United States)

    Brown, J.

    2003-12-01

    . Cryosol (Antarctic soil map, soil database). 4. Glacier and Permafrost Hazards in High Mountains (interaction of ice and permafrost on slopes). 5. Isotopes and Geochemistry of Permafrost (paleo-reconstruction, modern processes). 6. Mapping and Modelling of Mountain Permafrost (standardize map legends and maps, multi-dimensional models). 7. Periglacial Processes and Environments (past and present processes, field manual of measurements). 8. Permafrost and Climate (monitoring, impact assessments, inter-comparisons of models). 9. Permafrost Astrobiology (survivability of life on planets and analogous Earth environments). 10. Permafrost Engineering (case studies, climate impacts on infrastructure). The Data Committee facilitates recovery of data, web access, and CD data production. These activities will provide added insight into past, present and future occurrences and responses of permafrost to climate change. They can contribute to activities of the International Polar Year. Results will be reported at the Ninth ICOP in Fairbanks, Alaska, in summer 2008. Current information is available on the IPA web site and in annual issues of Frozen Ground.

  5. Technical-Environmental Permafrost Observatories (TEPO) of northern West Siberia

    Science.gov (United States)

    Kurchatova, A. N.; Griva, G. I.; Osokin, A. B.; Smolov, G. K.

    2005-12-01

    During the last decade one of the most developed topics in environmental studies was the effect of global climate change. This has been shown to be especially pronounced in northern regions, having an important influence on the subsequent transformation of frozen soil distribution and potential permafrost degradation. In West Siberia such studies are especially important with the prospect of plans for development of oil-gas fields (Yamal, Gydan and Kara Sea shelf). Presently the enterprises independently determine the necessary research for ecological control of the territory. Therefore, the Tyumen State Oil and Gas University (TSOGU) together with one of the leading gas enterprises "Nadymgasprom" started to create an observational network along the meridian transect of northern West Siberia (Yamal-Nenets administrative district). Observational network consists from a number of monitoring sites - Technical-Environmental permafrost Observatories (TEPO). The research complex includes temperature observations in boreholes (depths of 30) equipped with automatic systems for registration and data collection; seasonal field investigations on spatial distribution and temporal variability of the snow cover and vegetation and soil distribution. TSOGU and "Nadymgasprom" plan for the realization of long-term monitoring to obtain representative results on permafrost-climate interaction. At present there are three monitoring observatories located in the main landscape types and gas fields in use since 1972 (Medvezhye), 1992 (Yubileynoe) and in development (Harasavey). The next contribution to International Polar Year (2007-2008) will be renewal of one of the former monitoring sites (established in 1972) with a long-term period of observation and creation of a new site at the Yamal peninsula (Arctic tundra zone). At the last site the installation of an automatic Climate-Soil Station is being planned in the framework of the INTAS Infrastructure Action project with cooperation of

  6. Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic: 14C characteristics of sedimentary carbon components and their environmental controls

    Science.gov (United States)

    Feng, Xiaojuan; Gustafsson, Örjan; Holmes, R. Max; Vonk, Jorien E.; Dongen, Bart E.; Semiletov, Igor P.; Dudarev, Oleg V.; Yunker, Mark B.; Macdonald, Robie W.; Wacker, Lukas; Montluçon, Daniel B.; Eglinton, Timothy I.

    2015-11-01

    Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. Through molecular 14C measurements, including novel analyses of suberin- and/or cutin-derived diacids (DAs) and hydroxy fatty acids (FAs), we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers (including plant wax lipids, cutin, suberin, lignin, and hydroxy phenols) in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial OC pools across the pan-Arctic. Terrestrial lipids, including suberin-derived longer-chain DAs (C24,26,28), plant wax FAs (C24,26,28), and n-alkanes (C27,29,31), incorporated significant inputs of aged carbon, presumably from deeper soil horizons. Mobilization and translocation of these "old" terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions. By contrast, shorter-chain (C16,18) DAs and lignin phenols (as well as hydroxy phenols in rivers outside eastern Eurasian Arctic) were much more enriched in 14C, suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers. Furthermore, the radiocarbon content of terrestrial markers is heavily influenced by specific OC sources and degradation status. Overall, multitracer molecular 14C analysis sheds new light on the mobilization of terrestrial OC from arctic watersheds. Our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial OC pools in the face of increasing arctic permafrost thaw.

  7. Subsurface Thermal Erosion Of Ice-Wedge Polygon Terrains: Implications For Arctic Geosystem In Transition

    Science.gov (United States)

    Fortier, D.; Godin, E.; Lévesque, E.; Veillette, A.

    2014-12-01

    Subsurface thermal erosion is triggered by convective heat transfers between flowing water and permafrost. For inland ice-wedge polygon terrains, heat advection due to infiltration of run-off in the massive ice wedges and the ice-rich upper portion of permafrost creates sink holes and networks of interconnected tunnels in the permafrost. Mass movements such as collapse of tunnel's roof, retrogressive thaw-slumping along exposed permafrost and active layer detachment slides lead to the development of extensive gully networks in the landscape. These gullies drastically change the hydrology of ice-wedge polygon terrains and the fluxes of heat, water, sediment and carbon within the permafrost geosystem. Exportation of sediments by fluvial processes within gullies are positive mechanical feed-back effects that keep gully channels active over decades. Along gully margins, drainage of disturbed polygons and ponds, slope drainage, soil consolidation, plant colonization of disturbed gully slopes and wet to mesic plant succession of drained polygons change the thermal properties of the active layer and create negative feedback effects that stabilize active erosion processes and promote permafrost recovery in gully slopes and adjacent disturbed polygons. On Bylot Island (Nunavut), over 40 gullies were mapped and monitored to characterize gully geomorphology, thermal and mechanical processes of gully erosion, rates of gully erosion over time within different sedimentary deposits, total volume of eroded permafrost at the landscape scale and gully hydrology. We conducted field and laboratory experiments to quantify heat convection processes and speed of ice wedge ablation in order to derive empirical equations to develop a numerical, fully-coupled, heat and mass (water) transfer model of ice-wedge thermal erosion. We used data collected over 10 years of geomorphological gully monitoring, regional climate scenarios, our physics-based numerical thermal erosion model and our field

  8. 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.

  9. Mapping ice-bonded permafrost with electrical methods in Sisimiut, West Greenland

    DEFF Research Database (Denmark)

    Ingeman-Nielsen, Thomas

    2006-01-01

    Permafrost delineation and thickness determination is of great importance in engineering related projects in arctic areas. In this paper, 2D geoelectrical measurements are applied and evaluated for permafrost mapping in an area in West Greenland. Multi-electrode resistivity profiles (MEP) have been...... collected and are compared with borehole information. It is shown that the permafrost thickness in this case is grossly overestimated by a factor of two to three. The difference between the inverted 2D resistivity sections and the borehole information is explained by macro-anisotropy due to the presence...... of horizontal ice-lenses in the frozen clay deposits. It is concluded that where the resistivity method perform well for lateral permafrost mapping, great care should be taken in evaluating permafrost thickness based on 2D resistivity profiles alone. Additional information from boreholes or other geophysical...

  10. Temporal Behavior of Lake Size-Distribution in a Thawing Permafrost Landscape in Northwestern Siberia

    Directory of Open Access Journals (Sweden)

    Johanna Mård Karlsson

    2014-01-01

    Full Text Available Arctic warming alters regional hydrological systems, as permafrost thaw increases active layer thickness and in turn alters the pathways of water flow through the landscape. Further, permafrost thaw may change the connectivity between deeper and shallower groundwater and surface water altering the terrestrial water balance and distribution. Thermokarst lakes and wetlands in the Arctic offer a window into such changes as these landscape elements depend on permafrost and are some of the most dynamic and widespread features in Arctic lowland regions. In this study we used Landsat remotely sensed imagery to investigate potential shifts in thermokarst lake size-distributions, which may be brought about by permafrost thaw, over three distinct time periods (1973, 1987–1988, and 2007–2009 in three hydrological basins in northwestern Siberia. Results revealed fluctuations in total area and number of lakes over time, with both appearing and disappearing lakes alongside stable lakes. On the whole basin scales, there is no indication of any sustained long-term change in thermokarst lake area or lake size abundance over time. This statistical temporal consistency indicates that spatially variable change effects on local permafrost conditions have driven the individual lake changes that have indeed occurred over time. The results highlight the importance of using multi-temporal remote sensing data that can reveal complex spatiotemporal variations distinguishing fluctuations from sustained change trends, for accurate interpretation of thermokarst lake changes and their possible drivers in periods of climate and permafrost change.

  11. PAST Gateways (Palaeo-Arctic Spatial and Temporal Gateways): Introduction and overview

    OpenAIRE

    O Cofaigh, Colm; Briner, Jason; Kirchner, Nina; Lucchi, R. G.; Meyer, Hanno; Kaufman, Darrell S.

    2016-01-01

    This special issue relates to the Second International Conference of the PAST Gateways (Palaeo-Arctic Spatial and Temporal Gateways) network which was held in Trieste, Italy in 2014. Twenty five papers are included and they address topics under four main themes: (1) The growth and decay of Arctic ice sheets; (2) Arctic sea ice and palaeoceanography; (3) Terrestrial Arctic environments and permafrost change; and (4) Holocene Arctic environmental change. Geographically the focus is circum-Arcti...

  12. GIPL1.3 simulated mean annual ground temperature (MAGT) in Celsius averaged for particular decade for the entire Alaskan permafrost domain. NAD83, Alaska Albers projection

    Data.gov (United States)

    Arctic Landscape Conservation Cooperative — This raster, created in 2010, is output from the Geophysical Institute Permafrost Lab (GIPL) model and represents simulated mean annual ground temperature (MAGT) in...

  13. GIPL1.3 simulated maximum active layer thickness (ALT) in meters averaged for particular decade for the entire Alaskan permafrost domain. NAD83, Alaska Albers projection

    Data.gov (United States)

    Arctic Landscape Conservation Cooperative — This raster, created in 2010, is output from the Geophysical Institute Permafrost Lab (GIPL) model and represents simulated active layer thickness (ALT) in meters...

  14. Vulnerability of permafrost carbon research coordination network

    Science.gov (United States)

    Schädel, C.; Schuur, E. A. G.; McGuire, A. D.; Canadell, J. G.; Harden, J.; Kuhry, P.; Romanovsky, V. E.; Turetsky, M. R.

    2012-04-01

    Approximately 1700 Pg of soil carbon are stored in the northern circumpolar permafrost zone, more than twice as much carbon than currently contained in the atmosphere. Permafrost thaw, and the microbial decomposition of previously frozen organic carbon, is considered one of the most likely positive feedbacks from terrestrial ecosystems to the atmosphere in a warmer world. Yet, the rate and form of release is highly uncertain but crucial for predicting the strength and timing of this carbon cycle feedback this century and beyond. Here we report on the first products of a new research coordination network (RCN) whose objective is to link biological C cycle research with well-developed networks in the physical sciences focused on the thermal state of permafrost. We found that published literature in the Science Citation Index identified with the search terms 'permafrost' and 'carbon' have increased dramatically in the last decade. Of total publications including those keywords, 86% were published since 2000, 65% since 2005, and 36% since 2008. The first RCN activity consisted of an expert elicitation that revealed the total effect of carbon release from permafrost zone soils in climate is expected to be up to 30-46 Pg C over the next three decades, reaching 242-324 Pg C by 2100 and potentially up to 551-710 Pg C over the next several centuries under the strongest warming scenario presented to the group. These values, expressed in billions of tons of C in CO2 equivalents, combine the effect of C released both as CO2 and as CH4 by accounting for the greater heat-trapping capacity of CH4. However, the higher global warming potential of CH4 means that almost half of the effect of future permafrost zone carbon emissions on climate forcing was expected by this group to be a result of CH4 emissions from wetlands, lakes, and other oxygen-limited environments where organic matter will be decomposing. These results demonstrate the vulnerability of organic C stored in near

  15. Technological monitoring of subgrade construction on high-temperature permafrost

    Institute of Scientific and Technical Information of China (English)

    Svyatoslav Ya. Lutskiy; Taisia V. Shepitko; Alexander M. Cherkasov

    2015-01-01

    Three stages of complex technological monitoring for the increase of high-temperature-permafrost soil bearing capacity are described. The feasibility of process monitoring to improve the targeted strength properties of subgrade bases on frozen soils is demonstrated. The rationale for the necessity of predictive modeling of freeze-thaw actions during the subgrade construction period is provided.

  16. Unmanned Platforms Monitor the Arctic Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    de Boer, Gijs; Ivey, Mark D.; Schmid, Beat; McFarlane, Sally A.; Petty, Rickey C.

    2016-02-22

    In the Arctic, drones and tethered balloons can make crucial atmospheric measurement to provide a unique perspective on an environment particularly vulnerable to climate change. Climate is rapidly changing all over the globe, but nowhere is that change faster than in the Arctic. The evidence from recent years is clear: Reductions in sea ice (Kwok and Unstersteiner, 2011) and permafrost (Romanovsky et al., 2002), in addition to modification of the terriestrial ecosystem through melting permafrost and shifting vegetation zones (burek et al., 2008; Sturm, et al., 2001), all point to a rapidly evolving.

  17. In situ petroleum hydrocarbon bioremediation in the Canadian Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Greer, C.; Bell, T.; Lee, K.; Delisle, S.; Kovanen, D.; Craig, D.; Juck, D. [National Research Council of Canada, Montreal, PQ (Canada). Biotechnology Research Inst.

    2010-07-01

    This presentation reported on the in-situ bioremediation of diesel contaminated soils at the Canadian Forces Station CFS-Alert, in the Arctic. The soil was amended with monoammonium phosphate (MAP). The operation was designed to take place in a 2 month period during the brief thaw season. This presentation described the installation of the bioventing stacks, the turning of soil, and the application of an oxygen release compound (ORC) at the surface of the permafrost. A significant decrease in petroleum hydrocarbons (PC) was noted over 2 months. The effect of MAP amendment was a slight decrease in biomass in the pristine environment and a significant increase in biomass in the contaminated environment. The alkB gene was found to be important in the biodegradation of alkanes. Stable isotope probing (SIP) was used to identify active organisms. This bioremediation study showed that even in harsh Arctic climates, soils that are moderately contaminated with petroleum hydrocarbons can be remediated effectively and economically via biodegradation. tabs., figs.

  18. The effect of misleading surface temperature estimations on the sensible heat fluxes at a high Arctic site – the Arctic turbulence experiment 2006 on Svalbard (ARCTEX-2006

    Directory of Open Access Journals (Sweden)

    J. Bareiss

    2009-08-01

    Full Text Available The observed rapid climate warming in the Arctic requires improvements in permafrost and carbon cycle monitoring, accomplished by setting up long-term observation sites with high-quality in-situ measurements of turbulent heat, water and carbon fluxes as well as soil physical parameters in an Arctic landscape. But accurate quantification and well adapted parameterizations of turbulent fluxes in polar environments presents fundamental problems in soil-snow-ice-vegetation-atmosphere interaction studies. One of these problems is the accurate estimation of the surface or aerodynamic temperature T(0 required to force most of the bulk aerodynamic formula currently used. Results from the Arctic-Turbulence-Experiment (ARCTEX-2006 performed on Svalbard during the winter/spring transition 2006 helped to better understand the physical exchange and transport processes of energy. The existence of an untypical temperature profile close to the surface in the Arctic spring at Svalbard could be proven to be one of the major issues hindering estimation of the appropriate surface temperature. Thus, it is essential to adjust the set-up of measurement systems carefully when applying flux-gradient methods that are commonly used to force atmosphere-ocean/land-ice models. The results of a comparison of different sensible heat-flux parameterizations with direct measurements indicate that only the use of a hydrodynamic three-layer temperature-profile model achieves enough accuracy for heat flux calculations as it reliably reproduces the temporal variability of the surface temperature.

  19. The effect of misleading surface temperature estimations on the sensible heat fluxes at a high Arctic site – the Arctic Turbulence Experiment 2006 on Svalbard (ARCTEX-2006

    Directory of Open Access Journals (Sweden)

    J. Lüers

    2010-01-01

    Full Text Available The observed rapid climate warming in the Arctic requires improvements in permafrost and carbon cycle monitoring, accomplished by setting up long-term observation sites with high-quality in-situ measurements of turbulent heat, water and carbon fluxes as well as soil physical parameters in Arctic landscapes. But accurate quantification and well adapted parameterizations of turbulent fluxes in polar environments presents fundamental problems in soil-snow-ice-vegetation-atmosphere interaction studies. One of these problems is the accurate estimation of the surface or aerodynamic temperature T(0 required to force most of the bulk aerodynamic formulae currently used. Results from the Arctic-Turbulence-Experiment (ARCTEX-2006 performed on Svalbard during the winter/spring transition 2006 helped to better understand the physical exchange and transport processes of energy. The existence of an atypical temperature profile close to the surface in the Arctic spring at Svalbard could be proven to be one of the major issues hindering estimation of the appropriate surface temperature. Thus, it is essential to adjust the set-up of measurement systems carefully when applying flux-gradient methods that are commonly used to force atmosphere-ocean/land-ice models. The results of a comparison of different sensible heat-flux parameterizations with direct measurements indicate that the use of a hydrodynamic three-layer temperature-profile model achieves the best fit and reproduces the temporal variability of the surface temperature better than other approaches.

  20. Soil Warming and Fertilization Effects on Growth Ring Widths of Arctic Shrubs - Application of a Novel Dendroecological Approach.

    Science.gov (United States)

    Iturrate Garcia, M.; Heijmans, M.; Schweingruber, F. H.; Niklaus, P. A.; Schaepman-Strub, G.

    2015-12-01

    Climate warming is suggested as the main driver of shrub expansion in arctic tundra regions. Shrub expansion may have consequences on biodiversity and climate, especially through its feedbacks with the energy budget. A better understanding of shrub expansion mechanisms, including growth rate patterns and stem anatomy changes, and their sensitivity to climate is needed in order to quantify related feedbacks. We present a novel dendroecological approach to determine the response of three arctic shrub species to increased soil temperature and nutrients. A full factorial block-design experiment was run for four years with a total of thirty plots. Six individuals of each species were sampled from each plot to test for treatment effects on growth rate and stem anatomy. We compared the ring width of the four years of experiment with the one of the four previous years. The preliminary results for Betula nana and Salix pulchra suggest a significant effect of the treatments on the growth ring width. The response is stronger in Salix pulchra than in Betula nana individuals. And, while Salix pulchra is more sensitive to the combined soil warming and fertilization treatment, Betula nana is to the fertilization treatment. We could not observe an effect of treatment on the stem anatomy, likely because bark thickness co-varies with age. We found significant positive correlations of cork, cortex and phloem thickness with xylem thickness (used as a proxy of age), and a significant difference in stem anatomy between species. The results suggest species-specific growth sensitivity to soil warming and nutrient enhancement. The use of experimental dendroecology by manipulating environmental conditions according to future climate scenarios and testing effects on shrub anatomy and annual growth will increase our understanding on shrub expansion mechanisms. Ongoing plant trait analysis and consecutive application in a 3D radiative transfer model will allow to quantify the feedback of

  1. Environmental and physical controls on northern terrestrial methane emissions across permafrost zones.

    Science.gov (United States)

    Olefeldt, David; Turetsky, Merritt R; Crill, Patrick M; McGuire, A David

    2013-02-01

    Methane (CH4 ) emissions from the northern high-latitude region represent potentially significant biogeochemical feedbacks to the climate system. We compiled a database of growing-season CH4 emissions from terrestrial ecosystems located across permafrost zones, including 303 sites described in 65 studies. Data on environmental and physical variables, including permafrost conditions, were used to assess controls on CH4 emissions. Water table position, soil temperature, and vegetation composition strongly influenced emissions and had interacting effects. Sites with a dense sedge cover had higher emissions than other sites at comparable water table positions, and this was an effect that was more pronounced at low soil temperatures. Sensitivity analysis suggested that CH4 emissions from ecosystems where the water table on average is at or above the soil surface (wet tundra, fen underlain by permafrost, and littoral ecosystems) are more sensitive to variability in soil temperature than drier ecosystems (palsa dry tundra, bog, and fen), whereas the latter ecosystems conversely are relatively more sensitive to changes of the water table position. Sites with near-surface permafrost had lower CH4 fluxes than sites without permafrost at comparable water table positions, a difference that was explained by lower soil temperatures. Neither the active layer depth nor the organic soil layer depth was related to CH4 emissions. Permafrost thaw in lowland regions is often associated with increased soil moisture, higher soil temperatures, and increased sedge cover. In our database, lowland thermokarst sites generally had higher emissions than adjacent sites with intact permafrost, but emissions from thermokarst sites were not statistically higher than emissions from permafrost-free sites with comparable environmental conditions. Overall, these results suggest that future changes to terrestrial high-latitude CH4 emissions will be more proximately related to changes in moisture, soil

  2. Microbes in thawing permafrost: the unknown variable in the climate change equation

    Energy Technology Data Exchange (ETDEWEB)

    Graham, David E [ORNL; Wallenstein, Matthew D [Colorado State University, Fort Collins; Vishnivetskaya, T. [University of Tennessee, Knoxville (UTK); Waldrop, Mark P. [U.S. Geological Survey, Menlo Park, CA; Phelps, Tommy Joe [ORNL; Pfiffner, Susan M. [University of Tennessee, Knoxville (UTK); Onstott, T. C. [Princeton University; Whyte, Lyle [McGill University, Montreal, Quebec; Rivkina, Elizaveta [Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences; Gilichinsky, David A [Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences; Elias, Dwayne A [ORNL; Mackelprang, Rachel [U.S. Department of Energy, Joint Genome Institute; Verberkmoes, Nathan C [ORNL; Hettich, Robert {Bob} L [ORNL; Wagner, Dirk [Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany; Wullschleger, Stan D [ORNL; Jansson, Janet [Lawrence Berkeley National Laboratory (LBNL)

    2012-01-01

    Considering that 25% of Earth s terrestrial surface is underlain by permafrost (ground that has been continuously frozen for at least 2 years), our understanding of the diversity of microbial life in this extreme habitat is surprisingly limited. Taking into account the total mass of perennially frozen sediment (up to several hundred meters deep), permafrost contains a huge amount of buried, ancient organic carbon (Tarnocai et al., 2009). In addition, permafrost is warming rapidly in response to global climate change (Romanovsky et al., 2010), potentially leading to widespread thaw and a larger, seasonally thawed soil active layer. This concern has prompted the question: will permafrost thawing lead to the release of massive amounts of carbon dioxide (CO2) and methane (CH4) into the atmosphere? This question can only be answered by understanding how the microbes residing in permafrost will respond to thaw, through processes such as respiration, fermentation, methanogenesis and CH4 oxidation (Schuur et al., 2009). Predicting future carbon fluxes is complicated by the diversity of permafrost environments, ranging from high mountains, southern boreal forests, frozen peatlands and Pleistocene ice complexes (yedoma) up to several hundred meters deep, which vary widely in soil composition, soil organic matter (SOM) quality, hydrology and thermal regimes (Figure 1). Permafrost degradation can occur in many forms: thaw can progress downward from seasonally-thawed active layer soils in warming climates or laterally because of changes in surface or groundwater flow paths (Grosse et al., 2011). Permafrost degradation can sometimes lead to dramatic changes in ecosystem structure and function

  3. 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.

  4. Circumpolar assessment of permafrost C quality and its vulnerability over time using long-term incubation data

    DEFF Research Database (Denmark)

    Schädel, Christina; Schuur, Edward A.G.; Bracho, Rosvel;

    2014-01-01

    High-latitude ecosystems store approximately 1700 Pg of soil carbon (C), which is twice as much C as is currently contained in the atmosphere. Permafrost thaw and subsequent microbial decomposition of permafrost organic matter could add large amounts of C to the atmosphere, thereby influencing...... the global C cycle. The rates at which C is being released from the permafrost zone at different soil depths and across different physiographic regions are poorly understood but crucial in understanding future changes in permafrost C storage with climate change. We assessed the inherent decomposability of C...... from the permafrost zone by assembling a database of long-term (>1 year) aerobic soil incubations from 121 individual samples from 23 high-latitude ecosystems located across the northern circumpolar permafrost zone. Using a three-pool (i.e., fast, slow and passive) decomposition model, we estimated...

  5. 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...

  6. National Atlas of Arctic: structure and creation approaches

    Directory of Open Access Journals (Sweden)

    N. S. Kasimov

    2015-01-01

    Full Text Available On the instructions of President and Government of the Russian Federation, works for development of National Atlas of Arctic are started in the country. In this article the authors present their ideas from viewpoint of geographers who are well experienced in the field of cartographic works. A structure of future Atlas and lines of approaches to its development are proposed. The totality of experiences of preparation of other geographical atlases in both, the USSR and Russia, as well as the latest achievements of cartography, aerospace sources and GIS-technologies are recommended to be used. The National Atlas of Arctic is understood as a collection of knowledge of spatial-temporal information about geographical, ecological, economic, historical-ethnographic, cultural and social features of the Arctic. This cartographic model of the territory is designed for using in a wide range of scientific, managing, economic, defensive and social activities. A hard copy of the atlas is intended to be used as scientific-reference publication while its electronic version will make it possible to renovate its content and to improve it by means of actualization according to various directions of its practical use 16 sections proposed in a draft of the Atlas content are as follows: introductory, geological structure, relief, mineral resources, environment evolution, climate, land waters, seas, seashores, snow cover, glaciers, permafrost, soils, flora and fauna, state of the environment and the Nature protection, population, economics, and prospects for future. The popular-scientific edition of the Atlas is intended for use by wide circle of readers and also as a textbook for all levels of education. Presentation of material in the Atlas should combine a high scientific level and accessible language. In a popular form it will clarify traditions of careful treatment to the Nature and the nature-protective ethics of religious confessions of local people

  7. Arctic Freshwater Ice and Its Climatic Role

    OpenAIRE

    Prowse, Terry; Alfredsen, Knut; Beltaos, Spyros; Bonsal, Barrie; Duguay, Claude; Korhola, Atte; McNamara, Jim; Vincent, Warwick F.; Vuglinsky, Valery; Weyhenmeyer, Gesa A.

    2011-01-01

    Freshwater ice dominates the Arctic terrestrial environment and significantly impacts bio-physical and socio-economic systems. Unlike other major cryospheric components that either blanket large expanses (e.g., snow, permafrost, sea ice) or are concentrated in specific locations, lake and river ice are interwoven into the terrestrial landscape through major flow and storage networks. For instance, the headwaters of large ice-covered rivers extend well beyond the Arctic while many northern lak...

  8. Acidobacteria dominate the active bacterial communities of Arctic tundra with widely divergent winter-time snow accumulation and soil temperatures.

    Science.gov (United States)

    Männistö, Minna K; Kurhela, Emilia; Tiirola, Marja; Häggblom, Max M

    2013-04-01

    The timing and extent of snow cover is a major controller of soil temperature and hence winter-time microbial activity and plant diversity in Arctic tundra ecosystems. To understand how snow dynamics shape the bacterial communities, we analyzed the bacterial community composition of windswept and snow-accumulating shrub-dominated tundra heaths of northern Finland using DNA- and RNA-based 16S rRNA gene community fingerprinting (terminal restriction fragment polymorphism) and clone library analysis. Members of the Acidobacteria and Proteobacteria dominated the bacterial communities of both windswept and snow-accumulating habitats with the most abundant phylotypes corresponding to subdivision (SD) 1 and 2 Acidobacteria in both the DNA- and RNA-derived community profiles. However, different phylotypes within Acidobacteria were found to dominate at different sampling dates and in the DNA- vs. RNA-based community profiles. The results suggest that different species within SD1 and SD2 Acidobacteria respond to environmental conditions differently and highlight the wide functional diversity of these organisms even within the SD level. The acidic tundra soils dominated by ericoid shrubs appear to select for diverse stress-tolerant Acidobacteria that are able to compete in the nutrient poor, phenolic-rich soils. Overall, these communities seem stable and relatively insensitive to the predicted changes in the winter-time snow cover.

  9. Seeing the risks of multiple Arctic amplifying feedbacks.

    Science.gov (United States)

    Carter, P.

    2014-12-01

    There are several potentially very large sources of Arctic amplifying feedbacks that have been identified. They present a great risk to the future as they could become self and inter-reinforcing with uncontrollable knock-on, or cascading risks. This has been called a domino effect risk by Carlos Duarte. Because of already committed global warming and the millennial duration of global warming, these are highly policy relevant. These Arctic feedback processes are now all operant with emissions of carbon dioxide methane and nitrous oxide detected. The extent of the risks from these feedback sources are not obvious or easy to understand by policy makers and the public. They are recorded in the IPCC AR5 as potential tipping points, as is the irreversibility of permafrost thaw. Some of them are not accounted for in the IPCC AR5 global warming projections because of quantitative uncertainty. UNEP issued a 2012 report (Policy Implications of Thawing Permafrost) advising that by omitting carbon feedback emissions from permafrost, carbon budget calculations by err on the low side. There is the other unassessed issue of a global warming safety limit for preventing uncontrollable increasing Arctic feedback emissions. Along with our paper, we provide illustrations of the Arctic feedback sources and processes from satellite imagery and flow charts that allows for their qualitative consideration. We rely on the IPCC assessments, the 2012 paper Possible role of wetlands permafrost can methane hydrates in the methane cycle under future climate change; a review, by Fiona M. O'Connor et al., and build on the WWF 2009 Arctic Climate Feedbacks: Global Implications. The potential sources of Arctic feedback processes identified include: Arctic and Far North snow albedo decline, Arctic summer sea ice albedo decline, Greenland summer ice surface melting albedo loss, albedo decline by replacement of Arctic tundra with forest, tundra fires, Boreal forest fires, Boreal forest die

  10. 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

    Science.gov (United States)

    Ci, Zhijia; Peng, Fei; Xue, Xian; Zhang, Xiaoshan

    2016-11-01

    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 in the QTP.

  11. Processes and modes of permafrost degradation on the Qinghai-Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Climate warming must lead the mainly air temperature controlled permafrost to degrade.Based on the numerical simulation,the process of permafrost degradation can be divided into five stages,i.e.,starting stage,temperature rising stage,zero geothermal gradient stage,talic layers stage,and disappearing stage,according to the shape of ground temperature profile.Permafrost on the Qinghai-Tibet Plateau (QTP) is generally considered a relic from late Pleistocene,and has been degenerating as a whole during Holocene.According to spatial-temporal compensation,the present thermal state discrepancy of permafrost in different areas on the QTP may correspond with their degradation stages.On the QTP,permafrost in the high and middle mountains belongs to temperature rising stage,the permafrost thermal state is transiting from late rising temperature stage to zero geothermal gradient stage that is distributed in the middle-low-mountains.Permafrost that is in a zero gradient stage mainly appears in the high plateau and valley,whereas the transition from zero gradient stage to talic layers stage of permafrost is located in the vicinity of the lower limit of permafrost,and permafrost is disappearing from margin of perennially frozen ground.There are two modes of perennially frozen ground thawing,thawing from top to bottom and thawing from bottom to top respectively.During the temperature rising stage,when the heat flux in the perennially frozen soil layer is less than that in the unfrozen soil underlying frozen soil layer,the geothermal flux is partly used to thaw the base of permafrost,and permafrost thaws from bottom to top.With the decrease of thermal gradient in the perennially frozen ground,the heat that is used to thaw permafrost base increases,and geothermal heat will be entirely consumed to thaw the base of permafrost until the temperature gradient reaches zero thermal gradient state.On the other hand,the disappearance of permafrost may be delayed by "thermal offset" and

  12. Preservation of labile organic matter in soils of drained thaw lakes in Northern Alaska

    Science.gov (United States)

    Mueller, Carsten W.; Rethemeyer, Janet; Kao-Kniffin, Jenny; Löppmann, Sebastian; Hinkel, Kenneth; Bockheim, James

    2014-05-01

    A large number of studies predict changing organic matter (OM) dynamics in arctic soils due to global warming. In contrast to rather slowly altering bulk soil properties, single soil organic matter (SOM) fractions can provide a more detailed picture of the dynamics of differently preserved SOM pools in climate sensitive arctic regions. By the study of the chemical composition of such distinctive SOM fractions using nuclear magnetic resonance spectroscopy (NMR) together with radiocarbon analyses it is possible to evaluate the stability of the major OM pools. Approximately 50-75% of Alaska's Arctic Coastal Plain is covered with thaw lakes and drained thaw lakes that follow a 5,000 yr cycle of development (between creation and final drainage), thus forming a natural soil chronosequence. The drained thaw lakes offer the possibility to study SOM dynamics affected by permafrost processes over millennial timescales. In April 2010 we sampled 16 soil cores (including the active and permanent layer) reaching from young drained lakes (0-50 years since drainage) to ancient drained lakes (3000-5500 years since drainage). Air dried soil samples from soil horizons of the active and permanent layer were subjected to density fractionation in order to differentiate particulate OM and mineral associated OM. The chemical composition of the SOM fractions was analyzed by 13C CPMAS NMR spectroscopy. For a soil core of a young and an ancient drained thaw lake basin we also analyzed the 14C content. For the studied soils we can show that up to over 25 kg OC per square meter are stored mostly as labile, easily degradable organic matter rich in carbohydrates. In contrast only 10 kg OC per square meter were sequestered as presumably more stable mineral associated OC dominated by aliphatic compounds. Comparable to soils of temperate regions, we found small POM (organo-mineral interfaces in the studied permafrost soils.

  13. Structure of Syngenetic Permafrost: New Data from the CRREL Permafrost Tunnel, Fox, Alaska

    Science.gov (United States)

    Kanevskiy, M.; Fortier, D.; Cysewski, M.; Shur, Y.; Jorgenson, T.

    2006-12-01

    Syngenetic permafrost formation is a complex process related to sedimentation in cold conditions when the base of the active layer rises up step by step in phase with the accumulation of deposits of various origin (alluvial, slope, aeolian, lacustrine, etc.) at the surface. Syngenetically frozen sediments usually have high silt particles content (up to 70-80%); slightly decomposed rootlets and buried organic-rich horizons; high ice content; ice wedges with big vertical length; rhythmically organized cryogenic structure specific for syngenetic permafrost. The well-known CRREL Permafrost Tunnel near Fairbanks Alaska offers excellent exposures of syngenetic permafrost. The section of Late Pleistocene deposits in the Tunnel is comprised mostly of syngenetically frozen aeolian and fluvial silts with sand lenses, partly reworked by thermal erosion which proceeded mainly along the large ice wedges. Gullies and underground channels cut in the Late Pleistocene permafrost were filled with ice and soils of different origins and cryogenic structures. The Permafrost Tunnel consists of a main shaft and an inclined winze. The former has been extensively studied during the last 40 years. However the permafrost in the winze has not been studied thoroughly even though the Late Wisconsinian syngenetic permafrost is better preserved there than in the main shaft. The main objective of our work was to map the cryostratigraphy (scale 1:20) of the winze. The results show the prevalence of syngenetic permafrost with a micro-lenticular cryostructure. The gravimetric moisture content of such sediments is very high and varies from 100 to 240%. The sediments which were formed in the tunnels cut in the permafrost and in the filled gullies are mostly stratified silts with lenses of sands and (sometimes) gravel. The gravimetric moisture content of these sediments varies from 70 to100% which is smaller than the water content of the Late Wisconsinian syngenetic permafrost. In the upper part of the

  14. Microbial populations in Antarctic permafrost: biodiversity, state, age, and implication for astrobiology.

    Science.gov (United States)

    Gilichinsky, D A; Wilson, G S; Friedmann, E I; McKay, C P; Sletten, R S; Rivkina, E M; Vishnivetskaya, T A; Erokhina, L G; Ivanushkina, N E; Kochkina, G A; Shcherbakova, V A; Soina, V S; Spirina, E V; Vorobyova, E A; Fyodorov-Davydov, D G; Hallet, B; Ozerskaya, S M; Sorokovikov, V A; Laurinavichyus, K S; Shatilovich, A V; Chanton, J P; Ostroumov, V E; Tiedje, J M

    2007-04-01

    Antarctic permafrost soils have not received as much geocryological and biological study as has been devoted to the ice sheet, though the permafrost is more stable and older and inhabited by more microbes. This makes these soils potentially more informative and a more significant microbial repository than ice sheets. Due to the stability of the subsurface physicochemical regime, Antarctic permafrost is not an extreme environment but a balanced natural one. Up to 10(4) viable cells/g, whose age presumably corresponds to the longevity of the permanently frozen state of the sediments, have been isolated from Antarctic permafrost. Along with the microbes, metabolic by-products are preserved. This presumed natural cryopreservation makes it possible to observe what may be the oldest microbial communities on Earth. Here, we describe the Antarctic permafrost habitat and biodiversity and provide a model for martian ecosystems.

  15. Optimization in the use of Air Convection Embankments for Protection of Underlying Permafrost

    DEFF Research Database (Denmark)

    Jørgensen, Anders Stuhr; Ingeman-Nielsen, Thomas

    2012-01-01

    Since the beginning of the 1990s a significant increase in the mean annual air temperatures has been recorded all over the arctic regions. This has lead to a degrading of permafrost, which is now threatening the stability of airport and road embankments. To minimize the damages caused by thaw set...

  16. A Quantification of Climate Feedback from Permafrost Degradation, Thermokarst-Lake Expansion, and Subsequent Methane Emission Under Climate Policy and Uncertainty

    Science.gov (United States)

    Schlosser, C. A.; Gao, X.; Sokolov, A. P.; Walter Anthony, K.

    2011-12-01

    A direct consequence of climate warming in the Arctic will be the likelihood of widespread permafrost degradation. Subsequent subsidence of the landscape and hydrologic changes would then support the expansion of saturated areas such as thermokarst lakes and wetlands. These conditions over regions of carbon-rich, yedoma soils present a strong potential for increased methane emissions. In this study, we quantify the future changes in the high latitude near-surface permafrost and methane emission from thermokarst lake regions from climate projections of the 21st century. For the model simulations, we use the MIT Integrated Global System Model (IGSM) framework, which considers the full range of plausible transient climate response (TCR), emissions uncertainty with or without greenhouse gas stabilization targets, as well as a provision for uncertainty in regional climate changes. To account for this regional climate-change uncertainty, we modify the geographic shifts in precipitation, temperature and radiation conditioned by results from general circulation models (GCMs) of the Intergovernmental Panel on Climate Change (IPCC) archive. The numerical experiments with the IGSM indicate that the Arctic undergoes widespread and nearly complete degradation of the (near-surface) permafrost under a "No Policy" case. The uncertainties in TCR, emissions, and regional climate change have little effect on this end-of-century outcome, but affect the dynamic response. Under an aggressive greenhouse stabilization target and the full range of uncertainties, the IGSM simulations substantially reduce the permafrost degradation extent. Subsequent to the permafrost degradation, the simulated expanse of saturated areas can be large (up to 50%), but the uncertainties in TCR and the regional climate response have a large impact in both the dynamic and the end-of-century response. The corresponding, inferred increases in methane emission rates by the end of the century from thermokarst lakes

  17. Nitrogen availability increases in a tundra ecosystem during five years of experimental permafrost thaw.

    Science.gov (United States)

    Salmon, Verity G; Soucy, Patrick; Mauritz, Marguerite; Celis, Gerardo; Natali, Susan M; Mack, Michelle C; Schuur, Edward A G

    2016-05-01

    Perennially frozen soil in high latitude ecosystems (permafrost) currently stores 1330-1580 Pg of carbon (C). As these ecosystems warm, the thaw and decomposition of permafrost is expected to release large amounts of C to the atmosphere. Fortunately, losses from the permafrost C pool will be partially offset by increased plant productivity. The degree to which plants are able to sequester C, however, will be determined by changing nitrogen (N) availability in these thawing soil profiles. N availability currently limits plant productivity in tundra ecosystems but plant access to N is expected improve as decomposition increases in speed and extends to deeper soil horizons. To evaluate the relationship between permafrost thaw and N availability, we monitored N cycling during 5 years of experimentally induced permafrost thaw at the Carbon in Permafrost Experimental Heating Research (CiPEHR) project. Inorganic N availability increased significantly in response to deeper thaw and greater soil moisture induced by Soil warming. This treatment also prompted a 23% increase in aboveground biomass and a 49% increase in foliar N pools. The sedge Eriophorum vaginatum responded most strongly to warming: this species explained 91% of the change in aboveground biomass during the 5 year period. Air warming had little impact when applied alone, but when applied in combination with Soil warming, growing season soil inorganic N availability was significantly reduced. These results demonstrate that there is a strong positive relationship between the depth of permafrost thaw and N availability in tundra ecosystems but that this relationship can be diminished by interactions between increased thaw, warmer air temperatures, and higher levels of soil moisture. Within 5 years of permafrost thaw, plants actively incorporate newly available N into biomass but C storage in live vascular plant biomass is unlikely to be greater than losses from deep soil C pools.

  18. New high through put approach to study ancient microbial phylogenetic diversity in permafrost

    Science.gov (United States)

    Spirina, E.; Cole, J.; Chai, B.; Gilichinksy, D.; Tiedje, J.

    2003-04-01

    The study of microbial diversity in the deep ancient permafrost can help to answer many questions: (1) what kind of mechanisms keeps microbial cells alive, (2) how many of phylogenetic groups exist in situ and never had been cultivated, (3) what is the difference between modern and ancient microorganisms? From this point, distinct environments were examined: Arctic and Antarctic modern soil and permafrost. 16S rDNA genes were amplified from genomic DNA extracted from both original frozen samples and the same samples incubated at 10oC for 8 weeks under both aerobic and anaerobic conditions to determine those capable to grow. High throughput DNA sequencing was performed on the cloned PCR products to obtain partial 16S rDNA gene sequences. The unique script was written to automatically compare over 2,000 partial sequences with those rrn sequences in the Ribosomal Database Project (RDP) release 8.1 using the SEQUENCE MATCH. Sequences were grouped into categories from the RDPs phylogenetic hierarchy based on the closest database matches. Investigation revealed significant microbial diversity; two phylogenetic groups were predominant in all samples: Proteobacteria and Gram Positive Bacteria. Microbial community composition within those groups is different from sample to sample. However, similar genera, such as Arthrobacter, Bacillus, Citrobacter, Caulobacter, Comamonas, Flavobacterium, Nocardioides, Pseudomonas, Rhodocyclus, Rhodococcus, Sphingobacterium, Sphingomonas, Streptococcus, Terrabacter appeared in both polar regions. The greatest microbial diversity was detected in Arctic surface samples. According to RDPs phylogenetic hierarchy those organisms are related to Proteobacteria_SD, Gram Positive Bacteria_SD, Leptospirillum-Nitrospira, Nitrospina_SD, Flexibacter-Cytophaga-Bacteroides, Planctomyces and Relatives. Both the aerobic and anaerobic low temperatures soil incubation yielded some microbes not detected in the original samples. It should be possible, using

  19. Methane dynamics regulated by microbial community response to permafrost thaw.

    Science.gov (United States)

    McCalley, Carmody K; Woodcroft, Ben J; Hodgkins, Suzanne B; Wehr, Richard A; Kim, Eun-Hae; Mondav, Rhiannon; Crill, Patrick M; Chanton, Jeffrey P; Rich, Virginia I; Tyson, Gene W; Saleska, Scott R

    2014-10-23

    Permafrost contains about 50% of the global soil carbon. It is thought that the thawing of permafrost can lead to a loss of soil carbon in the form of methane and carbon dioxide emissions. The magnitude of the resulting positive climate feedback of such greenhouse gas emissions is still unknown and may to a large extent depend on the poorly understood role of microbial community composition in regulating the metabolic processes that drive such ecosystem-scale greenhouse gas fluxes. Here we show that changes in vegetation and increasing methane emissions with permafrost thaw are associated with a switch from hydrogenotrophic to partly acetoclastic methanogenesis, resulting in a large shift in the δ(13)C signature (10-15‰) of emitted methane. We used a natural landscape gradient of permafrost thaw in northern Sweden as a model to investigate the role of microbial communities in regulating methane cycling, and to test whether a knowledge of community dynamics could improve predictions of carbon emissions under loss of permafrost. Abundance of the methanogen Candidatus 'Methanoflorens stordalenmirensis' is a key predictor of the shifts in methane isotopes, which in turn predicts the proportions of carbon emitted as methane and as carbon dioxide, an important factor for simulating the climate feedback associated with permafrost thaw in global models. By showing that the abundance of key microbial lineages can be used to predict atmospherically relevant patterns in methane isotopes and the proportion of carbon metabolized to methane during permafrost thaw, we establish a basis for scaling changing microbial communities to ecosystem isotope dynamics. Our findings indicate that microbial ecology may be important in ecosystem-scale responses to global change.

  20. 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; Chen, Guangsheng; Chen, Xiaodong; Delire, Christine; Jafarov, Elchin; MacDougall, Andrew H.; Marchenko, Sergey; Nicolsky, Dmitry; 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

    2016-07-01

    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 CO2 and 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-1 between 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 jointly develop data sets

  1. 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.

  2. High Methylmercury in Arctic and Subarctic Ponds is Related to Nutrient Levels in the Warming Eastern Canadian Arctic.

    Science.gov (United States)

    MacMillan, Gwyneth A; Girard, Catherine; Chételat, John; Laurion, Isabelle; Amyot, Marc

    2015-07-01

    Permafrost thaw ponds are ubiquitous in the eastern Canadian Arctic, yet little information exists on their potential as sources of methylmercury (MeHg) to freshwaters. They are microbially active and conducive to methylation of inorganic mercury, and are also affected by Arctic warming. This multiyear study investigated thaw ponds in a discontinuous permafrost region in the Subarctic taiga (Kuujjuarapik-Whapmagoostui, QC) and a continuous permafrost region in the Arctic tundra (Bylot Island, NU). MeHg concentrations in thaw ponds were well above levels measured in most freshwater ecosystems in the Canadian Arctic (>0.1 ng L(-1)). On Bylot, ice-wedge trough ponds showed significantly higher MeHg (0.3-2.2 ng L(-1)) than polygonal ponds (0.1-0.3 ng L(-1)) or lakes (waters of Subarctic thaw ponds near Kuujjuarapik (0.1-3.1 ng L(-1)). High water MeHg concentrations in thaw ponds were strongly correlated with variables associated with high inputs of organic matter (DOC, a320, Fe), nutrients (TP, TN), and microbial activity (dissolved CO2 and CH4). Thawing permafrost due to Arctic warming will continue to release nutrients and organic carbon into these systems and increase ponding in some regions, likely stimulating higher water concentrations of MeHg. Greater hydrological connectivity from permafrost thawing may potentially increase transport of MeHg from thaw ponds to neighboring aquatic ecosystems.

  3. Symbiosis of Marshes and Permafrost in Da and Xiao Hinggan Mountains in Northeastern China

    Institute of Scientific and Technical Information of China (English)

    JIN Huijun; SUN Guangyou; YU Shaopeng; JIN Rui; HE Ruixia

    2008-01-01

    Recently, the degradation of permafrost and marsh environments in the Da and Xiao Hinggan Mountainshas become a great concern as more human activities and pronounced climate warming were observed during the past30 years and projected for the near future. The distribution patterns and development mechanisms of the permafrostand marshes have been examined both in theories and in field observations, in order to better understand the symbiosisof permafrost and marshes. The permafrost and marshes in the Da and Xiao Hinggan Mountains display discerniblezonations in latitude and elevation. The marsh vegetation canopy, litter and peat soil have good thermal insulationproperties for the underlying permafrost, resulting in a thermal offset of 3℃ to 4℃ and subsequently suppressing soiltemperature, In addition, the much higher thermal conductivity of frozen and ice-rich peat in the active layer is condu-cive to the development or in favor of the protection of permafrost due to the semi-conductor properties of the soilsoverlying the permafrost. On the other hand, because permafrost is almost impervious, the osmosis of water in marshsoils can be effectively reduced, timely providing water supplies for helophytes growth or germination in spring. In theDa and Xiao Hinggan Mountains, the permafrost degradation has been accelerating due to the marked climate warming,ever increasing human activities, and the resultant eco-environmental changes. Since the permafrost and marsh envi-ronments are symbiotic and interdependent, they need to be managed or protected in a well-coordinated and integratedway.

  4. Stability and biodegradability of organic matter from Arctic soils of Western Siberia: Insights from 13C-NMR spectroscopy and elemental analysis

    Science.gov (United States)

    Ejarque, Elisabet; Abakumov, Evgeny

    2016-04-01

    Arctic soils contain large amounts of organic matter which, globally, exceed the amount of carbon stored in vegetation biomass and in the atmosphere. Recent studies emphasize the potential sensitivity for this soil organic matter (SOM) to be mineralised when faced with increasing ambient temperatures. In order to better refine the predictions about the response of SOM to climate warming, there is a need to increase the spatial coverage of empirical data on SOM quantity and quality in the Arctic area. This study provides, for the first time, a characterisation of SOM from the Gydan Peninsula in the Yamal Region, Western Siberia, Russia. On the one hand, soil humic acids and their humification state were characterised by measuring the elemental composition and diversity of functional groups using solid-state 13C-NMR spectroscopy. Also, the total mineralisable carbon was measured. Our results show that there is a predominance of aliphatic carbon structures, with a distribution of functional groups that has a minimal variation both regionally and within soil depth. Such vertical homogeneity and low level of aromaticity reflects the accumulation in soil of lowly decomposed organic matter due to cold temperatures. Mineralisation rates were found to be independent of SOM quality, and to be mainly explained solely by the total carbon content. Overall, our results provide further evidence on the sensitivity that the soils of Western Siberia may have to increasing ambient temperatures and highlight the important role that this region can play in the global carbon balance under the effects of climate warming.

  5. Quantifying Net Carbon Exchanges Between the Atmosphere and Terrestrial Biosphere in the Arctic: What Have We Learned through Decade Regional Modeling Studies?

    Science.gov (United States)

    Zhuang, Q.

    2014-12-01

    Observed Arctic warming has been projected to continue in this century. Permafrost degradation is thus expected to continue, exposing large amounts of carbon for decomposition. Dynamics of Arctic landscape and hydrology are complicated due to changing climate and thawing permafrost, affecting the carbon biogeochemical cycling in the region. Further, human activities together with changing climate transform the regional land use and land cover, including wildfires, logging, and agricultural land conversion. This presentation will review the effects of factors, controls, and processes as well as landscape types (e.g., forests vs. lakes) on carbon biogeochemistry based on regional modeling studies and observations. Specific effects on carbon dynamics to be discussed will include: 1) thawing permafrost; 2) fire disturbances; 2) atmospheric carbon dioxide; 3) inorganic and organic nitrogen uptake by plants; 4) priming; 5) aerobic and anaerobic organic matter decomposition; and 6) various complexities of microbial physiology of soils. Partitioning the contribution of these processes to regional carbon dynamics shall help us improve the terrestrial biogeochemistry models, an important component of Earth System Models that are used to project our future climate.

  6. 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.

  7. Forests on thawing permafrost: fragmentation, edge effects, and net forest loss.

    Science.gov (United States)

    Baltzer, Jennifer L; Veness, Tyler; Chasmer, Laura E; Sniderhan, Anastasia E; Quinton, William L

    2014-03-01

    Much of the world's boreal forest occurs on permafrost (perennially cryotic ground). As such, changes in permafrost conditions have implications for forest function and, within the zone of discontinuous permafrost (30-80% permafrost in areal extent), distribution. Here, forested peat plateaus underlain by permafrost are elevated above the surrounding permafrost-free wetlands; as permafrost thaws, ground surface subsidence leads to waterlogging at forest margins. Within the North American subarctic, recent warming has produced rapid, widespread permafrost thaw and corresponding forest loss. Although permafrost thaw-induced forest loss provides a natural analogue to deforestation occurring in more southerly locations, we know little about how fragmentation relates to subsequent permafrost thaw and forest loss or the role of changing conditions at the edges of forested plateaus. We address these knowledge gaps by (i) examining the relationship of forest loss to the degree of fragmentation in a boreal peatland in the Northwest Territories, Canada; and (ii) quantifying associated biotic and abiotic changes occurring across forest-wetland transitions and extending into the forested plateaus (i.e., edge effects). We demonstrate that the rate of forest loss correlates positively with the degree of fragmentation as quantified by perimeter to area ratio of peat plateaus (edge : area). Changes in depth of seasonal thaw, soil moisture, and effective leaf area index (LAIe ) penetrated the plateau forests by 3-15 m. Water uptake by trees was sevenfold greater in the plateau interior than at the edges with direct implications for tree radial growth. A negative relationship existed between LAIe and soil moisture, suggesting that changes in vegetation physiological function may contribute to changing edge conditions while simultaneously being affected by these changes. Enhancing our understanding of mechanisms contributing to differential rates of permafrost thaw and associated

  8. Methane from the East Siberian Arctic shelf

    DEFF Research Database (Denmark)

    Petrenko...[], Vasilii V.; Etheridge, David M.

    2010-01-01

    that the release of Arctic CH4 was implied in previous climate shifts as well as in the recently renewed rise in atmospheric CH4. These claims are not supported by all the literature they cite. Their reference 5 (1) presents measurements of emissions only of carbon dioxide, not CH4. Their reference 8 (2), a study......In their Report “Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf” (5 March, p. 1246), N. Shakhova et al. write that methane (CH4) release resulting from thawing Arctic permafrost “is a likely positive feedback to climate warming.” They add...

  9. Arctic hydrology and meteorology. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Kane, D.L.

    1988-12-31

    The behavior of arctic ecosystems is directly related to the ongoing physical processes of heat and mass transfer. Furthermore, this system undergoes very large fluctuations in the surface energy balance. The buffering effect of both snow and the surface organic soils can be seen by looking at the surface and 40 cm soil temperatures. The active layer, that surface zone above the permafrost table, is either continually freezing or thawing. A large percentage of energy into and out of a watershed must pass through this thin veneer that we call the active layer. Likewise, most water entering and leaving the watershed does so through the active layer. To date, we have been very successful at monitoring the hydrology of Imnavait Creek with special emphasis on the active layer processes. The major contribution of this study is that year-round hydrologic data are being collected. An original objective of our study was to define how the thermal and moisture regimes within the active layer change during an annual cycle under natural conditions, and then to define how the regime will be impacted by some imposed terrain alteration. Our major analysis of the hydrologic data sets for Imnavait Creek have been water balance evaluations for plots during snowmelt, water balance for the watershed during both rainfall and snowmelt, and the application of a hydrologic model to predict the Imnavait Creek runoff events generated by both snowmelt and rainfall.

  10. Calculation of thawing of the soil foundations with the surface basements of a low-rise buildings in permafrost%多年冻土区低层建筑地下室土基的解冻计算

    Institute of Scientific and Technical Information of China (English)

    Terenty A.Kornilov; Igor I.Rozhin; Ekaterina A.Kononova; Dmitry A.Grigoriev; Ayyna N.Danilova

    2014-01-01

    Thawing of permafrost soil foundations of low-rise buildings with surface basements has been studied by the methods of mathematical modeling .The model takes into account air temperature changes , total solar radiation , surface albedo , thickness of snow cover and changes of coefficient of heat transfer between atmosphere and the Earth surface during a year .The influence of building dimensions , thermal resistance of plinth panel and thermal conditions of soil on dynamics of thawed bowl have been investiga -ted in the computational experiment .Comparative assessment of the results of calculation of the depth of thawing revealed that the depth of thaw calculated by existing standards , is considerably underestimated and does not depend on the thermal resistance of plinth panel .Moreover the standards do not take into account initial thermal conditions of soil and annual changes of atmospheric temperature .%对多年冻土区低层建筑地下室的解冻可通过数学建模的方法研究。该模型考虑了空气温度的变化、太阳总辐射、地表反照率以及一年中大气和地球表面之间的热传递系数的变化。建筑尺寸影响的研究,是基于基座面板的热阻和热条件土壤解冻动力学计算实验进行的。比较评估的计算融化深度结果显示,现有的解冻深度的标准,大大低估了和不依赖于基座面板的热阻。此外,该标准不考虑初始土壤热状况和大气温度的年际变化。

  11. Assessing climate impacts and risks of ocean albedo modification in the Arctic

    Science.gov (United States)

    Mengis, N.; Martin, T.; Keller, D. P.; Oschlies, A.

    2016-05-01

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

  12. Methane Emissions from Permafrost Regions using Low-Power Eddy Covariance Stations

    Science.gov (United States)

    Burba, G.; Sturtevant, C.; Schreiber, P.; Peltola, O.; Zulueta, R.; Mammarella, I.; Haapanala, S.; Rinne, J.; Vesala, T.; McDermitt, D.; Oechel, W.

    2012-04-01

    Methane is an important greenhouse gas with a warming potential 23 times that of carbon dioxide over a 100-year cycle. The permafrost regions of the world store significant amounts of organic materials under anaerobic conditions, leading to large methane production and accumulation in the upper layers of bedrock, soil and ice. These regions are currently undergoing dramatic change in response to warming trends, and may become a significant potential source of global methane release under a warming climate over the coming decades and centuries. Presently, most measurements of methane fluxes in permafrost regions have been made with static chamber techniques, and very few were done with the eddy covariance approach using closed-path analyzers. Although chambers and closed-path analyzers have advantages, both techniques have significant limitations, especially for permafrost research. Static chamber measurements are discrete in time and space, and particularly difficult to use over polygonal tundra with highly non-uniform micro-topography and active water layer. They also may not capture the dynamics of methane fluxes on varying time scales (hours to annual estimates). In addition, placement of the chamber may disturb the surface integrity causing a significant over-estimation of the measured flux. Closed-path gas analyzers for measuring methane eddy fluxes employ advanced technologies such as TDLS (Tunable Diode Laser Spectroscopy), ICOS (Integrated Cavity Output Spectroscopy), WS-CRDS (wavelength scanned cavity ring-down spectroscopy), but require high flow rates at significantly reduced optical cell pressures to provide adequate response time and sharpen absorption features. Such methods, when used with the eddy covariance technique, require a vacuum pump and a total of 400-1500 Watts of grid power for the pump and analyzer system. The weight of such systems often exceeds 100-200 lbs, restricting practical applicability for remote or portable field studies. As a

  13. Hydrology modifies ecosystem responses to warming through interactions between soil, leaf and canopy processes in a high Arctic ecosystem

    Science.gov (United States)

    Maseyk, K. S.; Welker, J. M.; Lett, C.; Czimczik, C. I.; Lupascu, M.; Seibt, U. H.

    2013-12-01

    Arctic ecosystems are experiencing temperature increases more strongly than the global average, and increases in precipitation are also expected amongst the climate impacts on this region in the future. These changes are expected to strongly influence both plant physiology and soil biogeochemistry, and therefore ecosystem carbon balance, hydrology and nutrient cycling. We have investigated the effects of a long-term (10 years) increase in temperature (T2), soil water (W) and the combination of both (T2W) on leaf-level structure and function and ecosystem CO2 and water fluxes in a tundra ecosystem at a field manipulation experiment in NW Greenland. Leaf-level gas exchange, chlorophyll fluorescence, carbon (C), nitrogen (N) and morphology were measured on Salix arctica plants in treatment and control plots in June-July 2011, and continuous measurements of net ecosystem fluxes of carbon and water were made using automatic chambers coupled to a trace gas analyzer. Contrasting responses to the treatments were observed between leaf-level and net ecosystem fluxes. Plants in the elevated temperature treatment had the highest leaf-level photosynthetic capacity in terms of net CO2 assimilation rates and photosystem II efficiencies, and lowest rates of non-photochemical energy dissipation during photosynthesis. The plants in the plots with both elevated temperatures and additional water had the lowest photosystem II efficiencies and the highest rates of non-photochemical energy dissipation. However, net photosynthetic rates remained similar to control plants with additional water, due in part to higher stomatal conductance (W) and lower dark respiration rates (T2W). In contrast, net ecosystem CO2 and water fluxes were highest in the T2W plots, due largely to a 35% increase in leaf area. Total growing season C accumulation was 3-5 times greater, water fluxes were 1.5-2 times higher, and water use efficiency was about 3 times higher in the combined treatment than the control

  14. Remediation of hydrocarbon contaminated soils in the Canadian Arctic with land farms

    Energy Technology Data Exchange (ETDEWEB)

    Paudyn, K.; Poland, J.S.; Rutter, A.; Rowe, R.K. [Queen' s Univ., Kingston, ON (Canada)

    2005-07-01

    Land farming is a process where petroleum contaminated soils are spread out in a layer 0.3-0.5 cm thick. Nutrients are added and the soils are mixed periodically, as both oxygen and water are necessary for aerobic petroleum hydrocarbon degradation. This paper discusses a trial land farm established at Resolution Island, Nunavut. Three truckloads of contaminated soil were excavated from 2 areas and displaced to a previously leveled area. Heavy equipment was used to homogenize the soil and evenly distribute material to each of four test plots, measuring 5 by 5 metres with a depth of 0.3 metres. Rock material was removed manually throughout the lifetime of the farm. Each plot was subjected to a different regime: a control plot with no action except soil collection; daily rototilling; rototilling every 4 days; and rototilling every 4 days with the addition of fertilizer. Plots were re-sampled after 16, 32, 17, 349, and 369 days. Nitrogen and phosphorus were added to the plot in the form of granular agricultural fertilizers. Results in all 4 plots showed a dramatic decrease in contaminant levels with time, possibly because disturbance of the soil in the creation of the land farm created conditions that promoted loss. Levels were calculated using chromatograms of extracted soil samples. For the 3 plots with no fertilizer, levels indicated that no measurable bioremediation was taking place. The addition of fertilizer is low maintenance and economical. However, the fertilized plot was also rototilled, so it is not yet known how important soil aeration is in assisting bioremediation. Laboratory experiments and the construction of a large scale land farm in 2004 should lead to the development of an optimal land farm operation protocol. 4 refs., 2 figs.

  15. Remediation of PCB contaminated soils in the Canadian Arctic: excavation and surface PRB technology.

    Science.gov (United States)

    Kalinovich, Indra; Rutter, Allison; Poland, John S; Cairns, Graham; Rowe, R Kerry

    2008-12-15

    The site BAF-5 is located on the summit of Resolution Island, Nunavut, just southeast of Baffin Island at 61 degrees 35'N and 60 degrees 40'W. The site was part of a North American military defense system established in the 1950s that became heavily contaminated with PCBs during and subsequent, its operational years. Remediation through excavation of the PCB contaminated soil at Resolution Island began in 1999 and at its completion in 2006 approximately 5 tonnes of pure PCBs in approximately 20,000 m3 of soil were remediated. Remediation strategies were based on both quantity of soil and level of contamination in the soil. Excavation removed 96% of the PCB contaminated soil on site. In 2003, a surface funnel-and-gate permeable reactive barrier was design and constructed to treat the remaining contamination left in rock crevices and inaccessible areas of the site. Excavation had destabilized contaminated soil in the area, enabling contaminant migration through erosion and runoff pathways. The barrier was designed to maximize sedimentation through settling ponds. This bulk removal enabled the treatment of highly contaminated fines and water through a permeable gate. The increased sediment loading during excavation required both modifications to the funnel and a shift to a more permeable, granular system. Granulated activated charcoal was chosen for its ability to both act as a particle retention filter and adsorptive filter. The reduction in mass of PCB and volume of soils trapped by the funnel of the barrier indicate that soils are re-stabilizing. In 2007, nonwoven geotextiles were re-introduced back into the filtration system as fine filtering could be achieved without clogging. Monitoring sites downstream indicate that the barrier system is effective. This paper describes the field progress of PCB remediation at Resolution Island.

  16. Potentiostatically Poised Electrodes Mimic Iron Oxide and Interact with Soil Microbial Communities to Alter the Biogeochemistry of Arctic Peat Soils

    Directory of Open Access Journals (Sweden)

    Largus T. Angenent

    2013-09-01

    Full Text Available Dissimilatory metal-reducing bacteria are ubiquitous in soils worldwide, possess the ability to transfer electrons outside of their cell membranes, and are capable of respiring with various metal oxides. Reduction of iron oxides is one of the more energetically favorable forms of anaerobic respiration, with a higher energy yield than both sulfate reduction and methanogenesis. As such, this process has significant implications for soil carbon balances, especially in the saturated, carbon-rich soils of the northern latitudes. However, the dynamics of these microbial processes within the context of the greater soil microbiome remain largely unstudied. Previously, we have demonstrated the capability of potentiostatically poised electrodes to mimic the redox potential of iron(III- and humic acid-compounds and obtain a measure of metal-reducing respiration. Here, we extend this work by utilizing poised electrodes to provide an inexaustable electron acceptor for iron- and humic acid-reducing microbes, and by measuring the effects on both microbial community structure and greenhouse gas emissions. The application of both nonpoised and poised graphite electrodes in peat soils stimulated methane emissions by 15%–43% compared to soils without electrodes. Poised electrodes resulted in higher (13%–24% methane emissions than the nonpoised electrodes. The stimulation of methane emissions for both nonpoised and poised electrodes correlated with the enrichment of proteobacteria, verrucomicrobia, and bacteroidetes. Here, we demonstrate a tool for precisely manipulating localized redox conditions in situ (via poised electrodes and for connecting microbial community dynamics with larger ecosystem processes. This work provides a foundation for further studies examining the role of dissimilatory metal-reducing bacteria in global biogeochemical cycles.

  17. Arctic River organic matter transport

    Science.gov (United States)

    Raymond, Peter; Gustafsson, Orjan; Vonk, Jorien; Spencer, Robert; McClelland, Jim

    2016-04-01

    Arctic Rivers have unique hydrology and biogeochemistry. They also have a large impact on the Arctic Ocean due to the large amount of riverine inflow and small ocean volume. With respect to organic matter, their influence is magnified by the large stores of soil carbon and distinct soil hydrology. Here we present a recap of what is known of Arctic River organic matter transport. We will present a summary of what is known of the ages and sources of Arctic River dissolved and particulate organic matter. We will also discuss the current status of what is known about changes in riverine organic matter export due to global change.

  18. Communicating Arctic Change (Invited)

    Science.gov (United States)

    Serreze, M.

    2009-12-01

    Nowhere on the planet are emerging signals of climate change more visible than in the Arctic. Rapid warming, a quickly shrinking summer sea ice cover, and thawing permafrost, will have impacts that extend beyond the Arctic and may reverberate around the globe. The National Snow and Ice Data Center (NSIDC) of the University of Colorado has taken a leading role in trying to effectively communicate the science and importance of Arctic change. Our popular “Sea Ice News and Analysis” web site tracks the Arctic’s shrinking ice cover and provides scientific analysis with language that is accurate yet accessible to a wide audience. Our Education Center provides accessible information on all components of the Earth’s cryosphere, the changes being seen, and how scientists conduct research. A challenge faced by NSIDC is countering the increasing level of confusion and misinformation regarding Arctic and global change, a complex problem that reflects the low level of scientific literacy by much of the public, the difficulties many scientists face in communicating their findings in accurate but understandable terms, and efforts by some groups to deliberately misrepresent and distort climate change science. This talk will outline through examples ways in which NSIDC has been successful in science communication and education, as well as lessons learned from failures.

  19. Coupled thermo-geophysical inversion for high-latitude permafrost monitoring - assessment of the method and practical considerations

    Science.gov (United States)

    Tomaskovicova, Sonia; Paamand, Eskild; Ingeman-Nielsen, Thomas; Bauer-Gottwein, Peter

    2013-04-01

    difference between the synthetic and the measured apparent resistivities is minimized in a least-squares inversion procedure by adjusting the thermal parameters of the heat model. A site-specific calibration is required since the relation between unfrozen water content and temperature is strongly dependent on the grain size of the soil. We present details of an automated permanent field measurement setup that has been established to collect the calibration data in Ilulissat, West Greenland. Considering the station location in high latitude environment, this setup is unique of its kind since the installation of automated geophysical stations in the Arctic conditions is a challenging task. The main issues are related to availability of adapted equipment, high demand on robustness of the equipment and method due to the harsh environment, remoteness of the field sites and related powering issues of such systems. By showing the results from the new-established geoelectrical station over the freezing period in autumn 2012, we prove the 2D time lapse resistivity tomography to be an effective method for permafrost monitoring in high latitudes. We demonstrate the effectivity of time lapse geoelectrical signal for petrophysical relationship calibration, which is enhanced comparing to sparse measurements.

  20. Dissolved organic matter photolysis in Canadian arctic thaw ponds

    Science.gov (United States)

    Laurion, Isabelle; Mladenov, Natalie

    2013-09-01

    The abundant thaw lakes and ponds in the circumarctic receive a new pool of organic carbon as permafrost peat soils degrade, which can be exposed to significant irradiance that potentially increases as climate warms and ice cover shortens. Exposure to sunlight is known to accelerate the transformation of dissolved organic matter (DOM) into molecules that can be more readily used by microbes. We sampled the water from two common classes of ponds found in the ice-wedge system of continuous permafrost regions of Canada, polygonal and runnel ponds, and followed the transformation of DOM over 12 days by looking at dissolved organic carbon (DOC) concentration and DOM absorption and fluorescence properties. The results indicate a relatively fast decay of color (3.4 and 1.6% loss d-1 of absorption at 320 nm for the polygonal and runnel pond, respectively) and fluorescence (6.1 and 8.3% loss d-1 of total fluorescent components, respectively) at the pond surface, faster in the case of humic-like components, but insignificant losses of DOC over the observed period. This result indicates that direct DOM mineralization (photochemical production of CO2) is apparently minor in thaw ponds compared to the photochemical transformation of DOM into less chromophoric and likely more labile molecules with a greater potential for microbial mineralization. Therefore, DOM photolysis in arctic thaw ponds can be considered as a catalytic mechanism, accelerating the microbial turnover of mobilized organic matter from thawing permafrost and the production of greenhouse gases, especially in the most shallow ponds. Under a warming climate, this mechanism will intensify as summers lengthen.

  1. Soil and Plant Mercury Concentrations and Pools in the Arctic Tundra of Northern Alaska by Hedge Christine, Obrist Daniel, Agnan Yannick, Moore Christopher, Biester Harald, Helmig Detlev

    Science.gov (United States)

    Hedge, C.; Agnan, Y.

    2015-12-01

    We present vegetation, soil and runoff mercury (Hg) concentrations and pool sizes in vegetation and soils at several arctic tundra sites, an area that represents <7 x 106 km2 of land surface globally. The primary measurement location is at Toolik Field Station (TFS, 68° 38' N) in northern Alaska, with additional samples collected along a transect from TFS to the Arctic Ocean, and in Noatak National Preserve to be collected in August 2015. Soil and vegetation samples from all sites will be analyzed for total Hg concentration, pH, soil texture, bulk density, soil moisture content, organic and total carbon (C), nitrogen, along with major and trace elements. Initial results already obtained from TFS (characterized as moist to wet tundra with Typic Aquiturbel soils) show Hg concentrations in tundra vegetation (112±15 μg kg-1) and organic soil (140±8 μg kg-1) similar to those found in temperate sites. Calculation of plant-based Hg deposition rates by litterfall of 17.3 μg kg-1 yr-1 were surprisingly high, exceeding all other Hg deposition fluxes at this site. Hg concentrations in mineral soils (95±3 μg kg-1) were 2-3 times higher than those found at temperate sites. Hg concentrations showed weak relationships to organic C concentrations contrasting patterns from temperate soils where concentrations typically decline with depth following lower organic carbon contents. In fact, vertical mass profiles of Hg showed a strong increase with depth, with mineral layers storing over 90% (200-500 g ha-1) of Hg within these soils. A principle component analysis including major and trace elements indicated that soil Hg was not of lithogenic origin but from atmospheric sources, possibly by long-range transport. Carbon-14 dating results showed over 7,000 years old organic carbon in mineral soils of the active layer where highest concentrations of soil Hg were observed, suggesting long term retention of atmospheric Hg. These patterns suggest vertical translocation of Hg from the

  2. Reassessment of the Genesis of "Thaw Lakes" on the Arctic Coastal Plain in Northern Alaska

    Science.gov (United States)

    Shur, Y.; Jorgenson, M. T.

    2004-12-01

    Oriented lakes and drained lake basins on the Arctic Coastal Plain in northern Alaska have been the subject of numerous studies for more than 50 years. From the beginning, the waterbodies have been described as "thaw lakes" and since then a thermokarst genesis for the lakes has been accepted without any quantitative analysis of the initial permafrost conditions and thaw-susceptibility of the upper permafrost. We initially sought to quantify ground ice changes in support of this concept through detailed permafrost and terrain studies in the northeastern NPRA, an area with thick deposits of loamy sand and abundant lakes. During 2001-2004 we conducted detailed terrain analyses that included field surveys, permafrost investigations, and photogrammetry. A terrain-unit approach was used to relate soil and ground ice properties to surficial deposits related to lake development. Cryogenic structures, ice volumes, and properties of upper permafrost were described from borehole cores taken from every stage of lake-basin development and in surrounding areas. Ground ice also was described and sampled at 20 exposures at lake and riverbanks. We classified stages of drained basin development and quantified their permafrost characteristics. The primary stage of lake development is usually described as degradation of ice-wedges at their intersections. A thaw bulb then develops under the deep water and the thaw lakes expand laterally through both mechanical and thermal erosion. Although we observed numerous ponds at ice-wedge crossings we did not observe later sequential stages of thaw lake development. Instead, we observed that initial shallow ponds were soon colonized by vegetation, which halted thermokarst. In addition, ice volumes and thaw settlement properties of soils were insufficient to allow thaw lake development. Under the standard concept of lake development, the formation of ice wedges raises the surface and allows the development of new thermokarst, and thus creates a

  3. Cold season soil respiration in response to grazing and warming in the High Arctic Svalbard

    DEFF Research Database (Denmark)

    Strebel, Ditte; Elberling, Bo; Morgner, Elke;

    2010-01-01

    ) and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Results reveal variations in soil carbon cycling, with significant seasonal trends controlled by temperature, water content and snow. Experimental warming (OTCs) increased near-surface temperatures in the growing season, resulting......The influence of goose grazing intensity and open-topped chambers (OTCs) on near-surface quantities and qualities of soil organic carbon (SOC) was evaluated in wet and mesic ecosystems in Svalbard. This study followed up a field experiment carried out in 2003-05 (part of the project Fragility...

  4. Effects of large herbivores on biodiversity of vegetation and soil microarthropods in low Arctic Greenland

    DEFF Research Database (Denmark)

    Aastrup, Peter; Raundrup, Katrine; Feilberg, Jon;

    This report summarizes the results of a project that aims at documenting long term effects of grazing by comparing baseline data inside and outside exclosures. We collected data on vascular plants, mosses, lichens, microarthropod abundance and food-web structure, soil nutrients, decomposition......, and soil temperature. Data provide a significant basis for understanding the interaction between large herbivores and vegetation in Greenland. The report contains documentation of data collected in 2009 and 2012 as well as documentation of data from 1984-2004 made available by Jon Feilberg....

  5. Numerical modeling of seasonally freezing ground and permafrost

    Science.gov (United States)

    Nicolsky, Dmitry J.

    2007-12-01

    This thesis represents a collection of papers on numerical modeling of permafrost and seasonally freezing ground dynamics. An important problem in numerical modeling of temperature dynamics in permafrost and seasonally freezing ground is related to parametrization of already existing models. In this thesis, a variation data assimilation technique is presented to find soil properties by minimizing the discrepancy between in-situ measured temperatures and those computed by the models. The iterative minimization starts from an initial approximation of the soil properties that are found by solving a sequence of simple subproblems. In order to compute the discrepancy, the temperature dynamics is simulated by a new implementation of the finite element method applied to the heat equation with phase change. Despite simplifications in soil physics, the presented technique was successfully applied to recover soil properties, such as thermal conductivity, soil porosity, and the unfrozen water content, at several sites in Alaska. The recovered properties are used in discussion on soil freezing/thawing and permafrost dynamics in other parts of this thesis. Another part of this thesis concerns development of a numerical thermo-mechanical model of seasonal soil freezing on the lateral scale of several meters. The presented model explains observed differential frost heave occurring in non-sorted circle ecosystems north of the Brooks Range in the Alaskan tundra. The model takes into account conservation principles for energy, linear momentum and mass of three constituents: liquid water, ice and solid particles. The conservation principles are reduced to a computationally convenient system of coupled equations for temperature, liquid water pressure, porosity, and the velocity of soil particles in a three-dimensional domain with cylindrical symmetry. Despite a simplified rheology, the model simulates the ground surface motion, temperature, and water dynamics in soil and explains

  6. Land Cover and Permafrost Change Mapping Using Dense Time Stacks of Landsat and Quickbird Imagery

    Science.gov (United States)

    Nyland, K. E.; Streletskiy, D. A.; Shiklomanov, N. I.

    2014-12-01

    Climate change is especially pronounced in the Arctic, and regions on permafrost are at the frontier of these changes. Increasing air temperatures affect the extent, type, and characteristics of permafrost which is critical to many natural phenomena and northern infrastructure. In areas of discontinuous permafrost certain land cover types are indicative of permafrost conditions making satellite imagery an important tool for assessing environmental change in these remote areas. In arctic environments remote sensing can be particularly challenging due to consistently high cloud cover, data gaps, and landscape heterogeneity. However, there has been success at dealing with such challenges in lower latitude regions using the emerging dense time stack methodology. In place of using an anniversary date for land cover comparisons from different years, this methodology includes scenes from all seasons in addition to imagery normally rejected due to data gaps and high amounts of cloud cover. The incorporation of all available data creates a "dense time stack" which provides both a more complete dataset and more nuanced spectral signatures for classification. This work applied the dense time stack method to mapping five drainage basins in the close vicinity of the city of Igarka, Russia using both Landsat and Quickbird satellite imagery. The resulting map series proved this method to be effective within the Arctic for multiscalar mapping both temporally (annual and seasonal) and spatially (at the resolutions of Landsat and Quickbird). The time series of observed land cover changes produced allowed areas of permafrost degradation to be identified. These maps will be applied in the future to ongoing hydrological research in the region investigating the sources of increased run off and its relation to permafrost degradation.

  7. Expert assessment of vulnerability of permafrost carbon to climate change

    Science.gov (United States)

    Schuur, E.A.G.; Abbott, B.W.; Bowden, W.B.; Brovkin, V.; Camill, P.; Canadell, J.G.; Chanton, J.P.; Chapin, F. S.; Christensen, T.R.; Ciais, P.; Crosby, B.T.; Czimczik, C.I.; Grosse, G.; Harden, J.; Hayes, D.J.; Hugelius, G.; Jastrow, J.D.; Jones, J.B.; Kleinen, T.; Koven, C.D.; Krinner, G.; Kuhry, P.; Lawrence, D.M.; McGuire, A.D.; Natali, Susan M.; O'Donnell, J. A.; Ping, C.-L.; Riley, W.J.; Rinke, A.; Romanovsky, V.E.; Sannel, A.B.K.; Schädel, C.; Schaefer, K.; Sky, J.; Subin, Z.M.; Tarnocai, C.; Turetsky, M.R.; Waldrop, M.P.; Anthony, K.M. Walter; Wickland, K.P.; Wilson, C.J.; Zimov, S.A.

    2013-01-01

    Approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafrost zone, more than twice as much C than in the atmosphere. The overall amount, rate, and form of C released to the atmosphere in a warmer world will influence the strength of the permafrost C feedback to climate change. We used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change. Experts were asked to provide quantitative estimates of permafrost change in response to four scenarios of warming. For the highest warming scenario (RCP 8.5), experts hypothesized that C release from permafrost zone soils could be 19–45 Pg C by 2040, 162–288 Pg C by 2100, and 381–616 Pg C by 2300 in CO2 equivalent using 100-year CH4 global warming potential (GWP). These values become 50 % larger using 20-year CH4 GWP, with a third to a half of expected climate forcing coming from CH4 even though CH4 was only 2.3 % of the expected C release. Experts projected that two-thirds of this release could be avoided under the lowest warming scenario (RCP 2.6). These results highlight the potential risk from permafrost thaw and serve to frame a hypothesis about the magnitude of this feedback to climate change. However, the level of emissions proposed here are unlikely to overshadow the impact of fossil fuel burning, which will continue to be the main source of C emissions and climate forcing.

  8. Soil-frost-enabled soil-moisture-precipitation feedback over northern high latitudes

    Science.gov (United States)

    Hagemann, Stefan; Blome, Tanja; Ekici, Altug; Beer, Christian

    2016-07-01

    Permafrost or perennially frozen ground is an important part of the terrestrial cryosphere; roughly one quarter of Earth's land surface is underlain by permafrost. The currently observed global warming is most pronounced in the Arctic region and is projected to persist during the coming decades due to anthropogenic CO2 input. This warming will certainly have effects on the ecosystems of the vast