April 2012 Permafrost Alert
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12047444 Arthur, E. (Aarhus University, Department of Agroecology, Tjele, Denmark); Schjonning, P.; Moldrup, P. and de Jonge, L. W. Soil resistance and resilience to mechanical stresses for three differently managed sandy loam soils: Geoderma, 173-174, p. 50-60, illus. incl. 4 tables, 52 ref., March 2012.
To improve our understanding of how clay-organic carbon dynamics affect soil aggregate strength and physical resilience, we selected three nearby soils (MFC, Mixed Forage Cropping; MCC, Mixed Cash Cropping; CCC, Cereal Cash Cropping) with identical clay content and increasing contents of organic carbon (CCC<MCC<MFC). The objective was to assess the resistance and resilience of the three soils to compaction using air permeability (ka), void ratio (e) and air-filled porosity (e) as functional indicators and to characterize aggregate stability, strength and friability. Aggregate tensile strength measurements were done at -1000hPa and in the air dried state. Soil cores were subjected to uniaxial confined compression (200kPa) followed by a period of natural recovery and wet-dry or freeze-thaw cycles. The MFC soil displayed greater tensile strength, specific rupture energy and friability at both soil-water potentials than the MCC and CCC soils possibly due to higher biotic binding of soil particles by the greater organic carbon content. The water dispersible clay was negatively correlated with the level of clay saturation by organic carbon. The resistance of the soils to compaction, quantified by both the compression index and a proposed functional index, was significantly greater for the MFC soil compared to the other two soils. The change in compression index with initial void ratio was significantly less for the MFC than the other soils. Plastic reorganization of the soil particles immediately after compaction, prior to removal of the load, was greatest for the high organic soil. Physical resilience after natural recovery followed the organic carbon gradient (MFC>MCC>CCC). After wet-dry cycles, the MFC soil showed a significantly greater resilience for all three indicators (ka, e and e). Resilience (ka, and e) after freeze-thaw cycles was significantly lower for the CCC soil than the MFC and MCC soils. A significant positive correlation between resistance and resilience was observed for ka and e but not for e. Resilience to compaction was found to be independent of the soil properties monitored.
12047472 Kjaergaard, Charlotte (Aarhus University, Department of Agroecology, Tjele, Denmark); Heiberg, Lisa; Jensen, Henning S. and Hansen, Hans Christian B. Phosphorus mobilization in rewetted peat and sand at variable flow rate and redox regimes: Geoderma, 173-174, p. 311-321, illus. incl. 6 tables, 60 ref., March 2012.
Despite the high priority of wetland restoration as the primary measure to reduce agricultural nutrient loads, it is also widely recognized that wetlands restored on former agricultural land could potentially release accumulated phosphorus (P) and become a source of eutrophication. Simulating the upward percolation of groundwater with variable O2 content and flow rate, we investigated the hydro-biogeochemical Fe and P dynamics in intact cores of a carbon rich peat and carbon poor sand. Percolation of deionized water with high, low or no O2 supply at 10°C caused markedly different in situ redox regimes in the two soils during 21 or 67 days of continuous percolation at either 1 or 4mmh-1. Anoxic conditions occurred in the peat soil at both low oxygen supply and anoxic infiltration, causing reductive Fe(III) dissolution with high Fe(II) and P effluent concentrations and total P (TP) release rates from 7.6 to 11mgPm-2day-1. Organic or particulate P contributed to 40-45% of total P losses from the peat. In contrast, the high O2 supply during high flow rate kept the peat oxic and lowered TP release rates to 6.7mgPm-2day-1. The carbon poor sand demonstrated that this soil type is not exposed to reducing conditions, unless the soil is actually infiltrated by anoxic water, causing an increase in TP release rates from 5.8 (oxic) to 7.6 (anoxic) mgPm-2day-1. Hydrology turned out as a major factor controlling TP release, as a four-fold increase in flow rate increased the P release rate in the sand from 5.8 to 24mgPm-2day-1. Thus, oxic conditions caused the sand to be the most critical soil in terms of P release with diffusion-limited desorption as the major mechanism, while at anoxic conditions P release following reductive Fe(III) dissolution in the peat soil was quantitatively most important. Effluent Fe(II):PO4-P molar ratios ranged between 10 and 40 (peat) and <3 (sand). Phosphorus release rates and soil P fractions indicate that both of these soils can potentially release P for several decades, however, reoxidation and readsorption of P at the redox boundary should be considered in terms of actual environmental impact.
12047441 Li Ruiping (Inner Mongolia Agricultural University, College of Water Conservancy and Civil Engineering, Huhhot, China); Shi Haibin; Flerchinger, G. N.; Akae, Takeo and Wang Changsheng. Simulation of freezing and thawing soils in Inner Mongolia Hetao irrigation district, China: Geoderma, 173-174, p. 28-33, illus. incl. 3 tables, sketch map, 32 ref., March 2012.
Inner Mongolia Hetao irrigation district, in north of China, is typical of seasonal frozen soil areas in the region. Irrigation in autumn is required to leach soil salt and to provide a reserve of soil water for the next year's crop. However, improper autumn irrigation results in the secondary salinization of soil. The objective of this study is to simulate soil water and heat dynamics during winter period with the one-dimensional Simultaneous Heat And Water (SHAW) model to assess its capability for simulating overwinter water storage. SHAW model soil parameters were calibrated by data of 1995-1996 and 2002-2004 and validated by data of 1996-2001 and 2005-2006 using field measured soil water contents and temperatures during freezing and thawing periods. Using calibrated and validated soil parameters, the paper simulates the process of soil freezing-thawing, and the dynamic variation of moisture-heat transfer, including soil water content, temperature, frost depth, soil evaporation, and water flux in the seasonal freezing-thawing period. These are useful to determine proper autumn irrigation management, and can be used in future research to address overwinter solute migration to reduce soil secondary salinization.
12043476 Pimentel, E. (ETH Zurich, Zurich, Switzerland); Papakonstatinou, S. and Anagnostou, G. Numerical interpretation of temperature distributions from three ground freezing applications in urban tunnelling: Tunnelling and Underground Space Technology, 28, p. 57-69, illus. incl. 2 tables, 20 ref., March 2012.
12041685 Pronost, Julie (Université Laval, Département de Géologie et Génie Géologique, Quebec City, QC, Canada); Beaudoin, Georges; Lemieux, Jean-Michel; Hébert, Réjean; Constantin, Marc; Marcouiller, Simon; Klein, Matthieu; Duchesne, Josée; Molson, John W.; Larachi, Faical and Maldague, Xavier. CO2-depleted warm air venting from chrysotile milling waste (Thetford Mines, Canada); evidence for in-situ carbon capture from the atmosphere: Geology (Boulder), 40(3), p. 275-278, illus., 18 ref., March 2012.
We have discovered diffuse warm air vents at the surface of a chrysotile milling waste heap at the Black Lake mine, Thetford Mines, Quebec, Canada. The venting areas are inconspicuous, except in winter when the vents form snow-free areas of unfrozen ground, each with a surface area of 1-15 m2. The temperature and chemical composition of the warm air vents have been monitored from March 2009 to July 2010. The temperature of the warm air and ground surface at the venting sites ranged from 6.6 to 20.0 °C, whereas that of the ambient air ranged from -13.2 to 20.0 °C. The difference between atmospheric and vent air temperatures is greater in cold-weather months. The warm air has low CO2 content, but has otherwise normal atmospheric gas composition. Warm air volumetric flow varies from 2.1 to 19.9 L/m2/s in winter, when it contains between <10 and 18 ppm CO2. In summer, the venting areas are more diffuse, with volumetric flow rates ranging from 0.5 to 1.5 L/m2/s, and are less depleted in CO2 (260-370 ppm). Frozen ground is likely focusing airflow in winter compared to summer. We present a conceptual model in which air enters the steep flanks of the chrysotile milling waste heap, into which CO2 reacts with Mg-rich minerals, stripping CO2 from air by exothermic mineral carbonation reactions. Considering the surface area of summer and winter venting areas, flow rates, and concentration of CO2 in warm air vents, we estimate that the Black Lake mine heap passively captures at least 0.6 kt CO2 per year.
12047439 Rasa, Kimmo (University of Helsinki, Department of Food and Environmental Sciences, Helsinki, Finland); Eickhorst, Thilo; Tippkötter, Rolf and Yli-Halla, Markku. Structure and pore system in differently managed clayey surface soil as described by micromorphology and image analysis: Geoderma, 173-174, p. 10-18, illus. incl. 5 tables, 46 ref., March 2012.
Water infiltration is a crucial process for functioning of vegetated buffer zones (BZ). Structure of a clayey surface soil of three differently managed BZs, i.e., 1) natural with no treatment, 2) harvested once a year and 3) grazed by cattle was investigated in this study. Soil macro pores (>50mm) were characterized by qualitative description and quantitative image analysis of soil thin sections in order to assess their capability to water infiltration. Less than 10% f the macro pores consisted of rounded and irregular pores smaller than 300mm indicating root activity. Instead, macro porosity was clearly dominated by elongated pores characterized by irregularity, expressing the complexity of the pore system. This pore pattern appeared in thin sections as weak or moderate ped separation suggesting good water infiltration when initially dry. Partial accommodation of pores may result in decrease of hydraulic conductivity, as these pores tend to close upon wetting and swelling. In the grazed site a platy structure was observed due to hoof pressure, which may further impair the hydraulic properties of soil. Moisture and temperature related processes (shrink-swell, freeze-thaw, and water saturation) are thought to be conducive to the aggregation and rearrangement of soil structure around the year, resulting in a complex pore system with low intra-aggregate porosity. In addition, wet periods typical of boreal soils result in clay dispersion and formation of aggregate-related pedofeatures of dense infillings, described as fine clay intrusions.
12039774 Algeo, Thomas (University of Cincinnati, Department of Geology, Cincinnati, OH); Henderson, Charles M.; Ellwood, Brooks B.; Rowe, Harry; Elswick, Erika; Bates, Steven; Lyons, Timothy W.; Hower, James C.; Smith, Christina; Maynard, Barry; Hays, Lindsay E.; Summons, Roger E.; Fulton, James and Freeman, Katherine H. Evidence for a diachronous Late Permian marine crisis from the Canadian Arctic region: Geological Society of America Bulletin, Pre-Issue Publication, illus. incl. sects., strat. cols., 2 plates, sketch map, 190 ref., February 6, 2012. WWW. With GSA Data Repository Item 2012072; accessed on March 29, 2012. IGCP Project No. 572.
A high-resolution chemostratigraphic study of a 24-m-thick section at West Blind Fiord on Ellesmere Island (Canadian Arctic) documents stepwise environmental deterioration in the marine Sverdrup Basin during the late Changhsingian (late Late Permian) as a result of volcanic disturbances to surrounding landmasses. A horizon within the upper Lindstrom Formation (datum A) is characterized by increased Fe-oxyhydroxide fluxes and weathering intensity as well as modest shifts toward more reducing water-mass conditions and higher marine productivity, recording an initial disturbance that washed soils into the marine environment. The contact between chert of the Lindstrom Formation and silty shale of the overlying Blind Fiord Formation, which is 1.6 m higher and ~50 k.y. younger than datum A, records a large increase in detrital sediment flux, more strongly enhanced marine productivity, and a regional extinction of siliceous sponges, herein termed the "Arctic extinction event." The horizon equivalent to the latest Permian mass extinction of Tethyan shallow-marine sections is 5.6 m higher and ~100 k.y. younger than the Arctic extinction event, demonstrating the diachronous nature of the marine biotic and environmental crisis at a global scale; it is associated with intensified anoxia and possible changes in phytoplankton community composition in the study section. Marine environmental deterioration in the Sverdrup Basin, probably triggered by terrestrial ecosystem deterioration and elevated detrital sediment fluxes, was under way by the early part of the late Changhsingian, well before the onset of main-stage Siberian Traps flood basalt volcanism. The event sequence at West Blind Fiord may record the deleterious effects of early-stage explosive silicic eruptions that affected the Boreal region, possibly through deposition of toxic gas and ash within a restricted latitudinal band, while having little impact on marine ecosystems in the peri-equatorial Tethyan region.
12037498 Amin, M. G. Mostofa (Aarhus University, Department of Agroecology, Tjele, Denmark); Petersen, Soren O. and Laegdsmand, Mette. Sorption of 17b-estradiol to pig slurry separates and soil in the soil-slurry environment: Journal of Environmental Quality, 41(1), p. 179-187, illus. incl. 4 tables, 48 ref., February 2012.
Contamination of freshwater by estrogens from manure applied to agricultural land is of grave concern because of the potentially harmful effects on aquatic life and human health. Recent developments in liquid manure (slurry) management include partial removal of particulate slurry dry matter (PSDM) by separation technologies, which may also remove parts of the estrogens and enhance infiltration of the slurry on field application and hence the interaction between estrogens and the soil matrix. This study investigated how 17b-estradiol (E2), a natural estrogen commonly found in pig manure, sorbs to agricultural soils, to different size fractions of pig slurry separates, and to soils amended with each size fraction to simulate conditions in the soil-slurry environment. A crude fiber fraction (SSI) was prepared by sieving (<500 mm)the solids removed by an on-farm separation process. Three other size fractions (SS2>SS3>SS4) were prepared from the liquid fraction of the separated slurry by sedimentation and centrifugation. Sorption experiments were conducted in 0.01 mol L-1 CaCl2 and in natural pig urine matrix. Sorption in 0.01 mol L-1 CaCl2 was higher than that in pig urine for all solids used. Sorption of E2 to soil increased with its organic carbon content for both liquid phases. The solid-liquid partition coefficients of slurry separates were 10 to 30 times higher than those of soils, but the organic carbon normalized partition coefficient values, reflecting sorption per unit organic carbon, were lower for slurry separates. Mixing slurry separates with soil increased the sorption of E2 to the solid phase significantly in the order: SS1<SS3<SS2 for both liquid phases. In contrast, SS4 reduced the sorption of E2 to the solid phase by increasing the sorption to suspended or dissolved organic matter. The study suggested that potentially 50 to 75% of E2 in slurry can be removed from the liquid fraction of slurry by physical separation.
12047412 Fritz, Michael (Alfred Wegener Institute for Polar and Marine Research, Department of Periglacial Research, Potsdam, Germany); Wetterich, Sebastian; Schirrmeister, Lutz; Meyer, Hanno; Lantuit, Hugues; Preusser, Frank and Pollard, Wayne H. Eastern Beringia and beyond; late Wisconsinan and Holocene landscape dynamics along the Yukon Coastal Plain, Canada: Palaeogeography, Palaeoclimatology, Palaeoecology, 319-320, p. 28-45, illus. incl. 6 tables, sects., sketch maps, 126 ref., February 15, 2012. Supplemental information/data is available in the online version of this article.
Terrestrial permafrost archives along the Yukon Coastal Plain (northwest Canada) have recorded landscape development and environmental change since the late Wisconsinan at the interface of unglaciated Beringia (i.e. Komakuk Beach) and the northwestern limit of the Laurentide Ice Sheet (i.e. Herschel Island). The objective of this paper is to compare the late glacial and Holocene landscape development on both sides of the former ice margin based on permafrost sequences and ground ice. Analyses at these sites involved a multi-proxy approach including: sedimentology, cryostratigraphy, paleoecology of ostracods, stable water isotopes in ground ice, hydrochemistry, and AMS radiocarbon and infrared stimulated luminescence (IRSL) dating. AMS and IRSL age determinations yielded full glacial ages at Komakuk Beach that is the northeastern limit of ice-free Beringia. Herschel Island to the east marks the late Wisconsinan limit of the northwest Laurentide Ice Sheet and is composed of ice-thrust sediments containing plant detritus as young as 16.2calkaBP that might provide a maximum age on ice arrival. Late Wisconsinan ice wedges with sediment-rich fillings on Herschel Island are depleted in heavy oxygen isotopes (mean d18O of -29.1ppm); this, together with low d-excess values, indicates colder-than-modern winter temperatures and probably reduced snow depths. Grain-size distribution and fossil ostracod assemblages indicate that deglaciation of the Herschel Island ice-thrust moraine was accompanied by alluvial, proluvial, and eolian sedimentation on the adjacent unglaciated Yukon Coastal Plain until ~11calkaBP during a period of low glacio-eustatic sea level. The late glacial-Holocene transition was marked by higher-than-modern summer temperatures leading to permafrost degradation that began no later than 11.2calkaBP and caused a regional thaw unconformity. Cryostructures and ice wedges were truncated while organic matter was incorporated and soluble ions were leached in the thaw zone. Thermokarst activity led to the formation of ice-wedge casts and deposition of thermokarst lake sediments. These were subsequently covered by rapidly accumulating peat during the early Holocene Thermal Maximum. A rising permafrost table, reduced peat accumulation, and extensive ice-wedge growth resulted from climate cooling starting in the middle Holocene until the late 20th century. The reconstruction of paleolandscape dynamics on the Yukon Coastal Plain and the eastern Beringian edge contributes to unraveling the linkages between ice sheet, ocean, and permafrost that have existed since the late Wisconsinan.
12047416 Meyer, Michael C. (Universität Innsbruck, Institut für Geologie und Paläontologie, Innsbruck, Austria); Spötl, Christoph; Mangini, Augusto and Tessadri, Richard. Speleothem deposition at the glaciation threshold; an attempt to constrain the age and paleoenvironmental significance of a detrital-rich flowstone sequence from Entrische Kirche Cave (Austria): Palaeogeography, Palaeoclimatology, Palaeoecology, 319-320, p. 93-106, illus. incl. 3 tables, sketch maps, 91 ref., February 15, 2012.
Proxy records from high-altitude locations predating the Last Glacial Maximum are rare but could provide invaluable insights into the response of alpine catchments to the rapid climate fluctuations which characterized the last glacial period. Here we present a detrital-rich flowstone record from Entrische Kirche Cave, an inneralpine cave situated close to the accumulation area of the Pleistocene ice-stream network of the European Alps that expanded repeatedly into the lowlands during glacial maxima. U-Th dating of this calcite is challenging due to high detrital Th. However, petrographic and stable isotope analyses in conjunction with associated clastic cave sediments provide useful insights into the climatic boundary conditions during speleothem formation and into the paleoenvironmental processes which operated in the ~2000m-high catchment above the cave. Our data show that millennial-scale temperature fluctuations had a first-order control on the periglacial activity and vegetation in the catchment which strongly influenced the formation and infiltration of detritus into the karst aquifer. The brown laminated and brown dendritic fabrics that compose much of the detrital-rich flowstone succession reflect these environmental processes. The temperature-dependence of periglacial and permafrost processes allows to constrain the amount of cooling relative to the present-day mean annual air temperature that is required to initiate detrital-rich calcite formation in Entrische Kirche Cave, i.e. -2.5°C (minimum) to -6°C (maximum), respectively. White inclusion-poor calcite that is intercalated with the detrital-rich calcite indicates warm (interstadial) conditions and geomorphological stability in the catchment area. One such phase has been U-Th dated to 88.3 ± 6.9ka (i.e. Greenland Interstadial 21 or 22).
12043193 Andersson, Malin (Geological Survey of Norway, Trondheim, Norway); Ottesen, Rolf Tore; Jartun, Morten; Eggen, Ola and Enqvist, Ann-Christine. PCB contamination from sampling equipment and packaging: Applied Geochemistry, 27(1), p. 146-150, illus. incl. 3 tables, 6 ref., January 2012.
Work reported in this paper suggests that there are cases of contamination of soil and water samples by polychlorinated biphenyls (PCB) from paper and plastic packaging. Soil samples, which have been stored in paper bags for more than 20 years, share a similar congener distribution as the bags. Analyses showed a predominance of light congeners. PCB-analyses of water also indicate that water samples could be contaminated by plastic packaging. All analytical results of solid material packaging, as well as soil stored in the packaging, show a high relative amount of light weight PCB congeners. The paper bags that were analysed are made of strong paper and very popular among geochemists because of their watertight quality. These paper bags were manufactured more than 20 years ago. The plastic packaging that was analysed was produced in 1997 and 2008. The analyses of plastic and paper show that the raw material that has been used in the production at different times contains a wide concentration range of PCB. Re-sealable plastic bags, which contained the highest levels of PCB of the plastic material, are used by researchers world-wide as sampling bags for soils and sediments. This paper raises an important issue that packaging may potentially contaminate the samples that they hold.
12043280 Cockell, Charles S. (University of Edinburgh, School of Physics and Astronomy, Edinburgh, United Kingdom); Balme, Matt; Bridges, John C.; Davila, Alfonso and Schwenzer, Susanne P. Uninhabited habitats on Mars: Icarus, 217(1), p. 184-193, illus., 136 ref., January 2012.
12047369 DeRoin, Nichole (University of Alaska, Fairbanks, Geophysical Institute, Fairbanks, AK) and McNutt, Stephen R. Rockfalls at Augustine Volcano, Alaska; the influence of eruption precursors and seasonal factors on occurrence patterns 1997-2009: Journal of Volcanology and Geothermal Research, 211-212, p. 61-75, illus. incl. sketch map, 36 ref., January 15, 2012. Includes appendices.
Rockfalls have been recorded in seismic data at Augustine Volcano from 1997 to the present. Typical events last about 30 s and have frequencies >4 Hz on stations within 5 km of the summit. Many rockfalls are well recorded on summit seismic stations, suggesting that they originate from the steep summit dome. Typical background years such as 2003 or 2004 had several dozen events in the summer and fall (June to November) that were strong enough to trigger an automatic event detection system. For example, 17 rockfalls were recorded in 2003; mostly in late summer when air temperatures were warm and rainfall rates were highest, and 28 events were recorded in 2004, also in late summer. In 2005, about eight months before the onset of the eruption of Augustine in January 2006, there was a significant increase in the number of rockfalls detected. This increase of surface rockfall activity occurred at nearly the same time as precursory earthquake activity increased beneath Augustine. Overall there were more than 340 rockfalls in 2005, consisting of both short (less than 30 s) and long (greater than 30 s) duration events. The high rate of rockfalls in 2005 constitutes a new class of precursory signal that needs to be incorporated into long-term monitoring strategies at Augustine and elsewhere. During the eruption, numerous rockfalls continued to occur, and block-and-ash flows dominated the seismic records when the volcano began a phase of dome growth and collapse. The high rates of rockfalls continued after the eruption ended, due the new unstable lava dome and adjacent tephra at the summit. As of 2009 the rockfall rates are still high, but are declining steadily.
12041219 Wen Zhi (Chinese Academy of Sciences, CAREERI, Laboratory of Frozen Soil Engineering, Gansu, China); Zhang Tingjun; Sheng Yu; Ma Wei; Wu Qingbai; Feng Wenjie and Sun Zhizhong. Managing ice-rich permafrost exposed during cutting excavation along Qinghai-Tibetan railway; experiences and implementation: Engineering Geology, 122(3-4), p. 316-327, illus., October 10, 2011. Based on Publisher-supplied data.
There is widespread ice-rich permafrost over Qinghai-Tibetan plateau. The exposure and subsequently thawing of ice-rich permafrost result in serious engineering and environmental consequences. However, it is often inevitable to expose ice-rich permafrost during the construction of railway, highway, or any engineering structures in permafrost regions. In this paper, we described the hazards induced from ice-rich permafrost exposure including slope instability, thermal slumping, soil erosion, frost heave and thaw settlement along Qinghai-Tibetan railway. The leading factors resulting in the occurrence of hazards were reviewed. Various remedial measures applied during the construction of Qinghai-Tibetan railway were introduced. The operation effects on avoiding failure or minimizing the damage consequence were discussed. The results show that ice-rich permafrost exposure generally causes cutting failure unless proper countermeasures are applied. Slope instability is the most serious damage for ice-rich permafrost cutting. Frost heaving and thaw settlement tend to damage the surface treatments and have lesser effects on railway operation. Experience shows that Coarse-grain soil replacement with insulation and drainage system are the most common measures to be applied. Cement concrete framework measure is more popular than turf covering and insulation covering due to its construction convenience and less cost. The results indicate that the treatment of turf covering is more suitable for ice-rich permafrost exposure than insulation covering due to high long-term performance rating and surface deformation adaptability. Retaining wall is an effective remedial measure to prevent slope failure of deep cut in permafrost regions. The field investigation shows that design and construction methods to deal with the exposure and thawing of ice-rich permafrost along Qinghai-Tibetan railway are efficient and these experiences are helpful for other projects in cold regions.
12036330 Abramov, A. A. (Rossiyskaya Akademiya Nauk, Institut Fiziko-Khimicheskikh i Biologicheskikh Problem Pochvovedeniya, Pushchino, Russian Federation); Sletten, R. S.; Rivkina, Ye. M.; Mironov, V. A. and Gilichinskiy, D. A. Geokriologicheskiye usloviya Antarktidy [Geocryological conditions in Antarctica]: Kriosfera Zemli, 15(3), p. 3-19 (English sum.), illus. incl. 4 tables, sketch maps, 79 ref., September 2011.
The review of the geocryological conditions of Antarctica and results obtained during our studies in collaboration with USA Antarctic Expedition (1995-1999) and Russian Antarctic Expedition within the framework of International Polar Year (2007/08) are presented. The severity of geocryological conditions increases in the following sequence: sub-Antarctic islands (Bellinsgausen station)--Bunger Hills (Oasis II station)--Schrimacher Hills (Novolazarevskaya station)--Laesemann Hills (Progress station)--Thala Hills (Molodezhnaya station)--Marie Byrd Land (Russkaya station)--Wilson Hills (Leningradskaya station). The most severe conditions have been found in Dry Valleys (American McMurdo station). Thereafter, mean ground temperatures decrease from close to zero values to -25-30° C, and the active layer depth is reduced from several meters to zero. The cryogenic processes are widespread in ice-free areas, and primary soil-forming processes affect the first centimeters from the day surface. The permafrost studied in the coastal ice-free areas is of Holocene and late Pleistocene age, and in Dry Valleys--late Miocene, middle and late Pleistocene. At the same time in Dry Valleys it is possible to find permafrost of an age up to 30 million years.
12036331 Kaplina, T. N. (Institute of Geological Engineering Surveys for Construction, Moscow, Russian Federation). Drevniye alasnyye kompleksy Severnoy Yakutii (Soobshcheniye 2) [Paleothermokarst landforms in northern Yakutia (Part 2)]: Kriosfera Zemli, 15(3), p. 20-30 (English sum.), illus., 47 ref., September 2011.
The ancient burial Alas Complex in cross-sections of the high Yedoma level on the shores of the Dmitri Laptev Strait is described. This complex is compared to Alas Complexes described earlier in cross-sections of Duvanny Yar on Kolyma and Achchagyi-Allaikha on the left bank of the Indigirka River. The ancient Alas complexes possess common structural features. The table formations are commonly found at the base of the sections while the alas accumulations occur in the upper part of Alas Complexes. Systems of pseudomorphs of ice wedges are commonly found along the boundaries of these formations. Thus, the structure of the ancient Alas Complexes is similar to the structure of the Holocene Alas Complexes. The ancient Alas Complexes as well as the Holocene Ice Complexes have resulted from lake thermokarst followed by sedimentation in the alases. In all considered cases the emergence of the ancient Alas Complexes was associated with dramatic environmental changes indicated by the transformation of vegetation from tundra-steppe into humid tundra and even into the taiga. This environmental transformation was primarily caused both by some temperature rise and by replacement of a regime of insufficient precipitation by one of excessive humidity. The question of the age of the reviewed ancient Alas Complexes cannot be considered resolved. The most likely intervals of Alas formation and accumulation of deposits in these Alases are the early Karginskiy (MIS-3, Duvanny Yar) and the Kazantsevskiy (MIS-5, Allaikha and the Dmitri Laptev Strait).
12036333 Kistanov, O. G. (Gazprom Yamburg, Novyy Urengoy, Russian Federation); Matkovskiy, V. N. and Stebunov, V. B. Monitoring nadmerzlotnykh vod v nasypnykh peschanykh gruntakh Zapolyarnogo mestorozhdeniya, Pur-Tazovskoye mezhdurech'ye [Monitoring of ground water in sand landfills above permafrost in the Zapolyarnoye oil and gas field, Pur-Taz Interfluve]: Kriosfera Zemli, 15(3), p. 43-50 (English sum.), illus. incl. 2 tables, sketch maps, 5 ref., September 2011.
In 2007-2008, during the geocryological monitoring in the territory of the Zapolyarnoye Field, the dynamics of ground water occurring in the planning embankments composed of silty sands was studied. The method of observation has been demonstrated and conditions for the occurrence of frost heave for anthropogenic areas have been identified.
12036332 Kravtsova, V. I. (Moskovskiy Gosudarstvennyy Universitet, Moscow, Russian Federation) and Tarasenko, T. V. Dinamika termokarstovykh ozer tsentral'noy Yakutii pri izmeneniyakh klimata s 1950 goda [Dynamics of thermokarst lakes under climate changes since 1950 in central Yakutia]: Kriosfera Zemli, 15(3), p. 31-42 (English sum.), illus. incl. sketch maps, 15 ref., September 2011.
The analysis of the dynamics of thermokarst lakes in central Yakutia has been fulfilled since 1950, during the period of air temperature increase. The research has been carried out for two test sites (between the Rivers Vilyui and Tyukyan and on the right bank of the Lena River in its middle part) using aerial photographs of 1950s, multitemporal satellite images of 1970-1980s and data of meteorological observations. Seasonal, interannual and long-term changes of areas of thermokarst lakes have been analyzed. The influence of human activity and forest fires on the thermokarst state in Central Yakutia has been considered.
12042795 Mortensen, Morten Fischer (National Museum of Denmark, Danish Prehistory, Copenhagen, Denmark); Birks, Hilary H.; Christensen, Charlie; Holm, Jorgen; Noe-Nygaard, Nanna; Odgaard, Bent Vad; Olsen, Jesper and Rasmussen, Kaare Lund. Lateglacial vegetation development in Denmark; new evidence based on macrofossils and pollen from Slotseng, a small-scale site in southern Jutland: Quaternary Science Reviews, 30(19-20), p. 2534-2550, illus. incl. 1 table, sketch map, 131 ref., September 2011.
This paper presents the first unambiguous terrestrial palaeoecological record for the late glacial "Bolling warming" in Denmark. Pollen and macrofossil stratigraphies from pre-Bolling to 10,800 cal yr BP are presented from a small kettle hole in Southwest Denmark, during which the lake basin developed from an immature stage after the deglaciation to complete infilling in the early Holocene. Results show that the recently deglaciated landscape bore a discontinuous vegetation of pioneer plants. After the Bolling warming, an open Dryas octopetala-Betula nana community developed with Helianthemum oelandicum. Subarctic species were dominant and local successions were probably delayed by relatively unstable and infertile soils. There is no indication of a climate cooling during the period corresponding to the Older Dryas, but the occurrence of several drought tolerant and steppe species indicates that the period was relatively dry. In the Allerod period the Dryas-B. nana vegetation was initially replaced by an open Salix and grass dominated vegetation and some 400 years later, the first tree birches were documented presumably occupying moist and sheltered soils while drier land remained open. In the Younger Dryas period trees disappeared and the vegetation became open again and dominated by subarctic species. Following climate warming at the Younger Dryas-Holocene transition a shrub community of Empetrum and Juniperus developed. After approximately 200 years it was replaced by birch forest. Overall, the late-glacial vegetation cover had a more open and patchy character than inferred from previous pollen studies as assessment of the vegetation succession based on macrofossil evidence is essential. The inferred general vegetation development corresponds well with results of other studies in the region. Canonical ordinations (RDA) indicate that vegetation changes at the landscape scale during the Lateglacial period were driven by changes in climate, soils and competition for light.
12036336 Pizhankova, Ye. I. (Moskovskiy Gosudarstvennyy Universitet, Moscow, Russian Federation). Termodenudatsiya v beregovoy zone Lyakhovskikh ostrovov (rezul'taty deshifrirovaniya aerokosmicheskikh snimkov) [Thermal abrasion of Lyakhovskiy Islands shores (interpretation of aerospace images)]: Kriosfera Zemli, 15(3), p. 61-70 (English sum.), illus. incl. 3 tables, 21 ref., September 2011.
The interpretation of aerospace images obtained within 50 years allowed us to establish the important space and time reguliarities of the Ice Complex thermal denudation caused by thermal abrasion on the coast of the Lyakhovskiy Islands. Three types of coasts have been identified according to the ratio of velocities of thermal abrasion and thermal denudation. The rates of thermal denudation, the size of thermo-terraces have been estimated. For the Bol. Lyakhovskiy Island the comparison of these parameters for the shores of southern and northeastern exposures is presented. A variety of natural factors affecting the destructive processes on the coast have been determined. The parameters of coastal dynamics on the shores with different cryolithological structures have been obtained.
12040881 Arnold, Lee J. (University of Wollongong, School of Earth and Environmental Sciences, Centre for Archaeological Science, Wollongong, N.S.W., Australia); Roberts, Richard G.; MacPhee, Ross D. E.; Haile, James S.; Brock, Fiona; Moller, Per; Froese, Duane G.; Tikhonov, Alexei N.; Chivas, Allan R.; Gilbert, M. Thomas P. and Willerslev, Eske. Paper II; Dirt, dates and DNA; OSL and radiocarbon chronologies of perennially frozen sediments in Siberia, and their implications for sedimentary ancient DNA studies: Boreas, 40(3), p. 417-445, illus. incl. strat. cols., 3 tables, sketch map, 66 ref., July 2011. Supplemental information/data is available in the online version of this article.
The sedimentary ancient DNA (sedaDNA) technique offers a potentially invaluable means of investigating species evolution and extinction dynamics in high-latitude environments. An implicit assumption of the sedaDNA approach is that the extracted DNA is autochthonous with the host deposit and that it has not been physically transported from older source deposits or reworked within the sedimentary profile by postdepositional mixing. In this paper we investigate whether these fundamental conditions are upheld at seven perennially frozen wetland sites across the Taimyr Peninsula and coastal lowlands of north-central Siberia. Optically stimulated luminescence (OSL) and radiocarbon (14C) dating are used to constrain the ages of both the inorganic and organic fractions of perennially frozen deposits from which sedaDNA of extinct and extant species have been recovered. OSL and 14C age/depth profiles, as well as single-grain equivalent dose (De) distribution characteristics, are used to assess the stratigraphic integrity of these sedaDNA sequences by (i) identifying the presence of primary or reworked organic and inorganic material, and (ii) examining the types of depositional and postdepositional processes that have affected specific sedimentary facies. The results of this study demonstrate that even though DNA preservation and stratigraphic integrity are commonly superior in perennially frozen settings, this does not, in itself, guarantee the suitability of the sedaDNA approach. The combined OSL and 14C chronologies reveal that certain perennially frozen sites may be poorly suited for sedaDNA analysis, and that careful site selection is paramount to ensuring the accuracy of any sedaDNA study--particularly for 'latest appearance date' estimates of extinct taxa.
12040880 Arnold, Lee J. (Centro Nacional de Investigación sobre la Evolución Humana, Burgos, Spain) and Roberts, Richard G. Paper I; Optically stimulated luminescence (OSL) dating of perennially frozen deposits in north-central Siberia; OSL characteristics of quartz grains and methodological considerations regarding their suitability for dating: Boreas, 40(3), p. 389-416, illus. incl. 1 table, sketch map, 91 ref., July 2011. Supplemental information/data is available in the online version of this article; includes appendix.
Optically stimulated luminescence (OSL) dating of coarse-grained quartz is increasingly being used as the main chronological tool in late Quaternary palaeoenvironmental reconstructions of Siberia. However, relatively little information has been published on the suitability of OSL dating for the various types of perennially frozen sediments found in this region. Here we provide a systematic examination of the quartz luminescence characteristics of 21 perennially frozen samples from the Taimyr Peninsula and adjacent coastal lowlands of north-central Siberia, and discuss their implications for the reliability of single-grain and multi-grain OSL chronologies in such contexts. The results of this study suggest that the quartz luminescence characteristics of these samples are, in principle, favourable for OSL dating but, in practice, require that a series of validation checks are made of the chosen experimental conditions. If these tests are satisfied, then reliable OSL chronologies should be obtained for sedimentary deposits in this region. Importantly, however, the single-grain and multi-grain aliquot equivalent dose (De) distribution characteristics for our samples reveal that there are advantages in targeting certain types of depositional settings for OSL dating studies of Siberian sediments. We also show that samples from the same depositional settings, and even from the same sites, do not necessarily display similar De distribution characteristics. The latter complication favours the use of single-grain analysis to unravel the bleaching and burial histories of young (mid- to late Holocene) sediments in these Arctic environments.
12040879 Szewczyk, Jan (Polish Geological Institute, National Research Institute, Warsaw, Poland) and Nawrocki, Jerzy. Deep-seated relict permafrost in northeastern Poland: Boreas, 40(3), p. 385-388, illus. incl. strat. col., geol. sketch maps, 18 ref., July 2011.
A research borehole drilled in northeastern Poland revealed a permafrost layer at least 93 m thick within the Cretaceous sedimentary succession below a depth of 357 m. Its entire thickness has not been determined, owing to the borehole depth limit (450 m). The relict of permafrost, unexpected in this part of Europe, is in the ice-water transition phase at a temperature close to 0°C. We estimate that the permafrost has been preserved in an area of several square kilometres located above the central part of the Suwalki anorthosite intrusion, which is covered by ~800 m of sedimentary rocks. We show that the remnants of the Last Glaciation, which ended at c. 13.4 ka BP, can, even at present, affect the thermal regime of the outer zone of the Earth's crust. These findings are of significant importance for the reconstruction of past climate conditions.
12046790 Altuhafi, Fatin (Imperial College, Department of Civil and Environmental Engineering, London, United Kingdom) and Baudet, Beatrice A. A hypothesis on the relative roles of crushing and abrasion in the mechanical genesis of a glacial sediment: Engineering Geology, 120(1-4), p. 1-9, illus., June 10, 2011. Based on Publisher-supplied data.
Relatively new techniques of optical microscopy and interferometry have been used combined with fractal and modal analyses to study possible deformation mechanisms in glacial sediment from Langjokull, Iceland. Previous studies have shown that the Langjokull till has reached an ultimate grading during deposition and transport. The results presented here add information on the deformation mechanisms that it may have suffered until and after reaching this ultimate grading. The modal and fractal analyses suggest high mechanical weathering. This is supported by the shape and texture of particles determined using the different imaging techniques of laser scanning, optical microscopy combined with three-dimensional image construction, interferometry and scanning electron microscopy. The larger particles have highly weathered surfaces, indicating severe abrasion to their surface during transport. The finer particles show less abrasion stamp and higher angularity. They also bear evidence of relatively fresh fractures. This seems to indicate that as the sediment became better distributed during transport, breakage moved from the larger to the smaller particles, with the larger grains only suffering abrasion. This supports the hypothesis of fractal breakage in this type of soil.
12036327 Fotiyev, S. M. (Rossiyskaya Akademiya Nauk, Sibirskoye Otdeleniye, Institut Kriosfery Zemli, Tyumen, Russian Federation). Mekhanizm formirovaniya in"yektsionnykh zhil l'da i gidrolakkolitov [Mechanism of ice veins and hydrolaccoliths formation]: Kriosfera Zemli, 15(2), p. 44-55 (English sum.), illus. incl. table, 24 ref., June 2011.
The mechanism of formation of injective ice veins and hydrolaccoliths piercing through the ice sheet and deforming it has been examined. The main source of water forming the ultrafresh ice in the sheets, veins, and cores of hydrolaccoliths has been determined. The results of impact of the injective water flow (piercing into the ice sheet through the yawning fissure) on the ice sheet and the lower layers of the frozen loam unit have been demonstrated. The results of the intrusion of hydrolaccolith into the ice sheet and the frozen loam unit have been considered.
12036324 Kaplina, T. N. (Institute of Engineering Survey for Construction, Moscow, Russian Federation). Drevniye alasnyye kompleksy Severnoy Yakutii (soobshcheniye 1) [Pleistocene alas complexes in northern Yakutia (Part 1)]: Kriosfera Zemli, 15(2), p. 3-13 (English sum.), illus., 29 ref., June 2011.
In addition to the late Pleistocene ice complex deposits (the Yedoma Suite), the cross-sections of the high Yedoma level of northern Yakutia also contain fragments (relics) of ancient ice complexes. There are ice complexes of the lower, middle and upper Pleistocene. The youngest (relief-generating) and the thickest ice complex was greatly reworked by thermokarst during the transition from the Pleistocene to Holocene, which resulted in widespread Holocene Alas Complexes in the lowlands. The ancient Alas Complexes, visible traces of revamping of the ancient ice complexes by thermokarst, can be often found in the cross-sections of the Yedoma level. These Alas Complexes underlie the young ice complex. The article describes ancient, buried Alas Complexes in the cross-sections of the Duvannyy yar on the Kolyma, on the left bank of the Indigirka River--on the Allaikha River (part 1) and on the shores of the Dmitri Laptev Strait (part 2). The ancient Alas Complexes possess common structural features and had resulted from the lake thermokarst, followed by sedimentation in the alases. Their structural features are similar to those of Holocene Alas Complexes.
12036328 Vasil'yev, A. A. (Rossiyskaya Akademiya Nauk, Sibirskoye Otdeleniye, Institut Kriosfery Zemli, Tyumen, Russian Federation); Streletskaya, I. D.; Shirokov, R. S. and Oblogov, G. E. Evolyutsiya kriolitozony pribrezhno-morskoy oblasti Zapadnogo Yamala pri izmenenii klimata [Coastal permafrost evolution in western Yamal Peninsula under climate change]: Kriosfera Zemli, 15(2), p. 56-64 (English sum.), illus., 24 ref., June 2011.
This paper presents the results of studies of the evolutionary features of permafrost in the coastal area of western Yamal. The coastal area scheme is developed in the context of heat transfer. Climate warming is accompanied by increased sea temperatures and a decrease in the thickness of seasonal sea ice. The temperature of permafrost in the continental area over the past 30 years has risen by 1.0-1.4° C. The annual temperature of saline sediments in the permafrost degradation area is about the freezing point. The depth of layer zero annual amplitude is 3.0-4.0 m. Recent formation of the permafrost occurs at low marine laydas. The average annual temperature of sediments here is about -3.5° C.
12036325 Zolotov, S. Yu. (Russian Academy of Sciences, Siberian Division, Institute of Climate and Ecological Monitoring, Tomsk, Russian Federation); Ippolitov, I. I.; Loginov, S. V.; Luchitskaya, I. O. and Belaya, N. I. Sravneniye dannykh reanaliza NCEP/NCAR profiley temperatury pochvy s dannymi izmereniy seti stantsiy na territorii Zapadnoy Sibiri [Comparison of data from the NCEP/NCAR reanalysis of temperature soil profiles with data from observation network in West Siberia]: Kriosfera Zemli, 15(2), p. 14-20 (English sum.), illus. incl. 2 tables, 12 ref., June 2011.
Comparison of the soil temperature profiles based on West Siberian station network measurements and the data of the NCEP/NCAR reanalysis has been made. The data of the soil temperature measurements levels were taken at depths of 0, 20, 40, 80, 160, 320 cm and the data of the reanalysis layers were taken at depths of 0-10, 10-200, 300 cm. The analysis has demonstrated that the data of the reanalysis during the winter time period yield overestimated values, and in the summer time period, underestimated values for the 0-10 cm layer at high correlation coefficients. The data of the reanalysis are always underestimated for the 10-200 cm layer. For these reasons, the corrections function between the data of the reanalysis and the data of measurements has been defined.
12036868 Viktorov, A. S. (Russian Academy of Sciences, Ye. M. Sergeyev Institute of Geoecology, Moscow, Russian Federation) and Kapralova, V. N. Primeneniye metodov matematicheskoy morfologii landshafta dlya otsenki riska porazheniya lineynykh inzhenernykh sooruzheniy opasnymi ekzogennymi geologicheskimi protsessami [Application of mathematical methods for landscape morphological analysis and assessment of geological hazards affecting linear engineering structures]: Geoekologiya (Moskva), 2011(2), p. 165-173 (English sum.), illus. incl. 2 tables, 9 ref., April 2011.
The paper deals with a new approach to risk assessment of impact by exogenous geological hazards on engineering structures based on the methods of mathematical morphology of landscape. Assumptions of the models are made for areas subject to soil subsidence, karst and thermokarst processes; being proved by the experimental data on thermokarst plains. Testing plots with thermokarst lakes have been digitized, and the convergence between theoretical assumptions and empirical data has been checked. The results obtained prove a good agreement between the empirical and theoretical data.
12036318 Anikin, G. V. (Rossiyskaya Akademiya Nauk, Sibirskoye Otdeleniye, Institut Kriosfery Zemli, Tyumen, Russian Federation); Plotnikov, S. N. and Spasennikova, K. A. Komp'yuternoye modelirovaniye teplomassoperenosa v sistemakh gorizontal'nogo okhlazhdeniya gruntov [Computer simulation of heat and mass transfer in systems of horizontal ground cooling]: Kriosfera Zemli, 15(1), p. 33-39 (English sum.), illus., 7 ref., March 2011.
Analysis and computer calculation of the work of systems of horizontal ground cooling have been fulfilled. The dependence of coolant temperature on the coordinates of the region of phase transition and the dependence of the rate of liquefied and gaseous coolant on the coordinates have been derived. The cases of turbulent and laminar flow of liquefied and gaseous coolant have been considered.
12036317 Konstantinov, P. Ya. (Rossiyskaya Akademiya Nauk, Sibirskoye Otdeleniye, Institut Merzlotovedeniya, Yakutsk, Russian Federation); Fedorov, A. N.; Machimura, T.; Ivakhana, G.; Yabuki, Kh.; Yizhima, Y. and Kostar, F. Ispol'zovaniye avtomaticheskikh registriruyushchikh ustroystv (loggerov) dlya temperaturnogo monitoringa mnogoletnemerzlykh gruntov [Use of automated recorders (data loggers) for permafrost temperature monitoring]: Kriosfera Zemli, 15(1), p. 23-32 (English sum.), illus. incl. table, sketch map, 28 ref., March 2011.
The application of automated temperature recorders (temperature data loggers) in thermal monitoring of the upper permafrost is examined. Based on the results of 10 years of use of temperature data loggers in Yakutia, recommendations are provided on the choice and preparation of data loggers for monitoring studies, and a description is given for selected foreign-made models. The design of drill holes and experimental plots with instruments for temperature data loggers is discussed. A protection method against soil moisture and frost heave during long-term use is proposed. The polypropylene pipes of small diameter are used for protection.
12036323 Myach, L. T. (Rossiyskaya Akademiya Nauk, Institut Global'nogo Klimata i Ekologii, Moscow, Russian Federation); Boltneva, L. I. and Sherstyukov, B. G. Izmeneniye klimaticheskikh usloviy i temperatury gruntov v rayone ozera Baykal vo vtoroy polovine XX i v nachale XXI veka [Change of climate and ground temperature in the Baikal region during the last half of the 20th century and beginning of the 21st century]: Kriosfera Zemli, 15(1), p. 80-90 (English sum.), illus. incl. 5 tables, sketch map, 23 ref., March 2011.
The dynamics of the 1967-2007 time series of annual and seasonal averages of air temperature, precipitation, snow cover depth, and soil temperature at depths of 80 and 160 cm for the Baikal region are analyzed. A certain decrease in the air and soil temperature trends is clearly observed in the dynamics of the time series in the late 1990s and early 2000s due to the cycle of relative air temperature fall. However, later in the 2000s the trend of the rise of these temperatures is observed again. For the specified period the mean-annual linear trend factors appeared on the average to be 0.042 and 0.039° C/year for air and soil temperature at the depth of 160 cm, respectively. A tendency towards an increase in precipitation and snow cover depth is also observed. The periods of maximum instability of air and soil temperature have been determined by the analysis of their 20-year moving averages and standard deviations. Using several scenarios of climate change, the predictive estimates of the air and soil temperatures are obtained up to 2025.
12036316 Olenchenko, V. V. (Rossiyskaya Akademiya Nauk, Sibirskoye Otdeleniye, Institut Neftegazovoy Geologii i Geofiziki, Novosibirsk, Russian Federation); Kozhevnikov, N. O.; Antonov, Ye. Yu.; Pospeyeva, Ye. V.; Potapov, V. V.; Shein, A. N. and Stefanenko, S. M. Rasprostraneniye tolshchi merzlykh porod v Chuyskoy vpadine (Gornyy Altay) po dannym elektromagnitnykh zondirovaniy [Spatial distribution of permafrost in the Chuya Depression (Gorny Altai) according to data from electromagnetic sounding]: Kriosfera Zemli, 15(1), p. 15-22 (English sum.), illus. incl. sect., sketch map, 13 ref., March 2011.
The results of electromagnetic soundings in the area of permafrost in the Cuyskaya Basin (Gorny Altai) are presented and discussed in this article. A sharp decrease in permafrost has been revealed based on the comparison of data of geophysical researches in 2009 with the results of drilling during the 1970s. This decrease had occurred presumably due to the formation of the taliks of the hydrogeogenic type. Features of disturbance of altitudinal zonality in the permafrost structure have been determined.
12036315 Romanovskiy, N. N. (Moskovskiy Gosudarstvennyy Universitet, Moscow, Russian Federation) and Tumskoy, V. Ye. Retrospektivnyy podkhod k otsenke sovremennogo rasprostraneniya i stroyeniya shel'fovoy kriolitozony Vostochnoy Arktiki [Retrospective approach to analysis of modern extent and structure of permafrost zone on the eastern Arctic continental shelf]: Kriosfera Zemli, 15(1), p. 3-14 (English sum.), illus. incl. sketch map, 63 ref., March 2011.
General principles of the retrospective approach to the study of the contemporary structure and history of the evolution of the cryolithozone of the East Arctic Shelf have been considered. This approach is based on mathematical modeling of shelf cryolithozone dynamics, using the complex of geocryological, geological, and paleogeographic data from the investigation area. In the conditions of the extremely poorly examined East Arctic Shelf's cryolithozone, the retrospective approach permits one to estimate the distribution and thickness of frozen and cooled ground in this territory, the gas hydrate stability zones, to reconstruct their dynamics during the middle-late Neopleistocene and Holocene. The basic advantages and shortcomings of the retrospective approach and the peculiarities of mathematical modeling have been examined. Further lines of development of this method have been revealed.
12036319 Vasil'chuk, Yu. K. (Moskovskiy Gosudarstvennyy Universitet, Moscow, Russian Federation). Gomogennyye i geterogennyye plastovyye ledyanyye zalezhi v mnogoletnemerzlykh porodakh [Homogeneous and heterogeneous ground ice in permafrost zones]: Kriosfera Zemli, 15(1), p. 40-51 (English sum.), illus., 51 ref., March 2011.
An essential genetic variety of massive ice complexes in permafrost thicknesses is shown. A new classification of massive ice complexes is proposed. Two new categories are introduced into systematization of massive ice complexes: homogeneous and heterogeneous massive ice complexes. Homogeneous massive ice complexes are those whose genesis, structure and properties are similar in all studied parts of the complex. The structure and properties of heterogeneous massive ice complexes change along the section, and they consist of two and more homogeneous massive ice bodies or combinations of homogeneous massive ice bodies. A principal graphic model of heterogeneous massive ice complexes formation is proposed.
12036321 Vasil'yeva, Z. A. (Rossyskiy Gosudarstvennyy Universitet Nefti i Gaza, Moscow, Russian Federation); Dzhafarov, D. S. and Ametova, T. A. Kosvennyye tekhnogennyye priznaki indikatsii gazogidratov v kriolitozone [Indirect signs of gas hydrate presence in the cryolithozone]: Kriosfera Zemli, 15(1), p. 61-67 (English sum.), illus., 8 ref., March 2011.
Complications at well drilling in the cryolithozone connected with gas hydrate decomposition are considered in order. These complications can be considered indirect signs of the technogenic character of the natural gas hydrated existence. For substantiation of the indirect signs of the gas hydrate presence in the cryolithozone the analysis of possible processes is carried out at opening gas hydrates strata with the use of mathematical modeling and analytical research. The reasons for the occurrence of revealed features and the phenomena accompanying them are considered. The relationship between gas-water-ice-hydrate phase transition in rocks and complications in the course of drilling is shown.
12036827 Gubaydullin, M. G. (Arkhangelsk State Technical University, Arkhangelsk, Russian Federation) and Makarskiy, Nickolai A. Otsenka sostoyaniya verkhnikh gorizontov mnogoletnemerzlykh porod na Ardalinskom neftegazodobyvayushchem komplekse po rezul'tatam monitoringa [Engineering assessment of upper permafrost horizons in the Ardalin oilfield based on thermal monitoring]: Geoekologiya (Moskva), 2011(1), p. 14-25 (English sum.), illus. incl. 3 tables, 3 ref., February 2011.
The technique and results of geotechnical monitoring are considered upon the oil-field development in Nenets autonomous region. It is shown that the application of special technologies for constructing oil-recovery facilities on pile foundations and for filling soil grounds 2.0-2.5 m high above the tundra surface allows us almost to eliminate the thermal influence of engineering structures on permafrost. The conditions are determined, upon which it is possible to provide the economic and potable water supply for oil-field workers using the limited subsurface water resources confined to tundra lake taliks.
12036829 Roman, L. T. (Moskovskiy Gosudarstvennyy Universitet im. M. V. Lomonosova, Moscow, Russian Federation) and Tsarapov, M. N. Otsenka ustoychivosti otkosov, slozhennykh ottaivayushchimi gruntami [Assessment of thawing grounds stability on slopes]: Geoekologiya (Moskva), 2011(1), p. 58-62 (English sum.), illus. incl. 2 tables, 14 ref., February 2011.
Some methods are proposed for determination of the minimal strength characteristics of a thawing soil, i.e., cohesional coefficient of friction. These characteristics correspond to the shear strength at the thawing limit. Their values are considered both with and without the account of the active pore pressure influence. Based on the experimental data, the equation is derived for the calculation of minimal experimental strength characteristics of thawing clay depending on its physical properties. The slope stability coefficients are compared with that have been obtained for the minimal and maximal shear strength conditions.
12041771 Chan, Marjorie A. (University of Utah, Department of Geology and Geophysics, Salt Lake City, UT); Nicoll, Kathleen; Ormö, Jens; Okubo, Chris and Komatsu, Goro. Utah's geologic and geomorphic analogs to Mars; an overview for planetary exploration: in Analogs for planetary exploration (Garry, W. Brent, editor; et al.), Special Paper - Geological Society of America, 483, p. 349-375, illus. incl. 1 table, sketch maps, 176 ref., 2011.
Utah offers spectacular geologic features and valuable analog environments and processes for Mars studies. Horizontal strata of the Colorado Plateau are analogous to Mars because the overprint of plate tectonics is minimal, yet the effects of strong ground motion from earthquakes or impacts are preserved in the sedimentary record. The close proximity of analog environments and lack of vegetative cover are advantages for field and remote-sensing studies. Dry, desert climate and modern wind processes of Utah are comparable to Mars and its current surface. Analogs in Utah include eolian, sabkha and saline bodies, glacial, lacustrine, spring, alluvial, fluvial, delta, and outflow channel depositional environments, as well as volcanic landforms and impact craters. Analogous secondary processes producing modification features include: diagenetic concretions, weathering and soils, sinkholes, sapping, knobs and pinnacles, crusts and varnish, and patterned grounds. Utah's physical and chemical environments are analogous to conditions on Mars where water existed and could support microorganisms. The development of Mars includes: ancient and modern depositional records, burial and diagenesis, uplift and tectonic alteration, and modern sculpting or weathering of the surface exposures. Recent satellite images are providing unprecedented details that rival the outcrop scale. Analogs in Utah are prime field localities that can be utilized in planning future robotic and human missions to Mars, and for teaching the next generation of planetary explorers.
12041761 Hauber, E. (Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, Berlin, Germany); Reiss, D.; Ulrich, M.; Preusker, F.; Trauthan, F.; Zanetti, M.; Hiesinger, H.; Jaumann, R.; Johansson, L.; Johnsson, A.; Olvmo, M.; Carlsson, E.; Johansson, H. A. B. and McDaniel, S. Periglacial landscapes on Svalbard; terrestrial analogs for cold-climate landforms on Mars: in Analogs for planetary exploration (Garry, W. Brent, editor; et al.), Special Paper - Geological Society of America, 483, p. 177-201, illus. incl. 2 tables, sketch map, 266 ref., 2011.
We present landforms on Svalbard (Norway) as terrestrial analogs for possible Martian periglacial surface features. While there are closer climatic analogs for Mars, e.g., the Antarctic Dry Valleys, Svalbard has unique advantages that make it a very useful study area. Svalbard is easily accessible and offers a periglacial landscape where many different landforms can be encountered in close spatial proximity. These landforms include thermal contraction cracks, slope stripes, rock glaciers, protalus ramparts, and pingos, all of which have close morphological analogs on Mars. The combination of remote-sensing data, in particular images and digital elevation models, with field work is a promising approach in analog studies and facilitates acquisition of first-hand experience with permafrost environments. Based on the morphological ambiguity of certain landforms such as pingos, we recommend that Martian cold-climate landforms should not be investigated in isolation, but as part of a landscape system in a geological context.
12036825 Ishkov, A. G. (Nauchno-Proizvodstvennaya Firma DIEM, Moscow, Russian Federation); Yarygin, G. A.; Kuz'min, Yu. O.; Luk'yanov, O. V. and Farafonov, A. S. Otsenka sovremennoy geodinamicheskoy opasnosti pri proyektirovanii i stroitel'stve magistral'nykh truboprovodov [Assessment of modern geodynamic hazards at the stages of pipeline planning and construction]: Nauka i Tehnika v Gazovoj Promyslennosti, 2011(1), p. 66-71 (English sum.), illus., 6 ref., 2011.
The paper highlight the stagewise procedure for contemporary geodynamic hazard assessment as part of developing the project documentation and the investment rationales for such projects as the Bovanenkovo-Ukhta gas trunkline system, the Ukhta-Torzhok, Sakhalin-Khabarovsk-Vladivostok, South Stream gas trunklines, and the gas trunkline from Severo-Kamennomysskoye gas and condensate field. the authors assess natural activation of fault zones within a linear part of gas trunklines that allows identifying hazardous tectonic fault zones having all the signs of contemporary super-intensive deformation with dislocation velocities accumulated during the gas pipeline operation period and exceeding the maximum values permissible for the gas pipeline design.
12036934 Lantuit, Hugues (Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany); Atkinson, David; Overduin, Pier Paul; Grigoriev, Mikhail; Rachold, Volker; Grosse, Guido and Hubberten, Hans-Wolfgang. Coastal erosion dynamics on the permafrost-dominated Bykovsky Peninsula, north Siberia, 1951-2006: Polar Research (Online), 30, 21 p., illus. incl. 4 tables, sketch map, 65 ref., 2011.
12041762 Soare, Richard J. (Dawson College, Department of Geography, Montreal, QC, Canada); Séjourné, Antoine; Pearce, Geoffrey; Costard, François and Osinski, Gordon R. The Tuktoyaktuk coastlands of northern Canada; a possible "wet" periglacial analog of Utopia Planitia, Mars: in Analogs for planetary exploration (Garry, W. Brent, editor; et al.), Special Paper - Geological Society of America, 483, p. 203-218, illus. incl. sketch maps, 90 ref., 2011.
Numerous landforms with traits that are suggestive of formation by periglacial processes have been observed in Utopia Planitia, Mars. They include: small-sized polygons, flat-floored depressions, and polygon trough or junction pits. Most workers agree that these landforms are late Amazonian and mark the occurrence of near-surface regolith that is (was) ice rich. The evolution of the Martian landforms has been explained principally by two disparate hypotheses. The first is the "wet hypothesis." It is derived from the boundary conditions and ice-rich landscape of regions such as the Tuktoyaktuk Coastlands, Canada, where stable liquid water is freely available as an agent of landscape modification. The second is the "dry" hypothesis. It is adapted from the boundary conditions and landscape-modification processes in the glacial Dry Valleys of the Antarctic, where mean temperatures are much colder than in the Tuktoyaktuk Coastlands, liquid water at or near the surface is rare, and sublimation is the principal agent of glacial mass loss. Here, we (1) describe the ice-rich landscape of the Tuktoyaktuk Coastlands and their principal periglacial features; (2) show that these features constitute a coherent assemblage produced by thaw-freeze cycles; (3) describe the landforms of Utopia Planitia and evaluate the extent to which "wet" or "dry" periglacial processes could have contributed to their formation; and (4) suggest that even if questions concerning the "wet" or "dry" origin of the Martian landforms remain open, "dry" processes are incapable of explaining the origin of the ice-rich regolith itself, from which the landforms evolved.
12046928 Trommer, Gabriele (University of Tübingen, Department of Geosciences, Tubingen, Germany); Siccha, Michael; Rohling, Eelco J.; Grant, Katherine; van der Meer, Marcel T. J.; Schouten, Stefan; Baranowski, U. and Kucera, Michal. Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial: Climate of the Past, 7(3), p. 941-955, illus. incl. 1 table, sketch map, 111 ref., 2011. Published in Climate of the Past Discussion: 8 April 2011, URL: http://www.clim-past-discuss.net/7/1195/2011/cpd-7-1195-2011.html; accessed in Feb., 2012.
This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktic foraminiferal fauna following high salinities during marine isotopic stage (MIS) 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea sea surface temperature (SST) increased from 21°C to 25°C, with about 3°C of this increase taking place during termination II. Changes in planktic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which--as in the Holocene--followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.
12041765 Williamson, Marie-Claude (Natural Resources Canada, Geological Survey of Canada, Ottawa, ON, Canada); Smyth, Helen R.; Peterson, Ronald C. and Lavoie, Denis. Comparative geological studies of volcanic terrain on Mars; examples from the Isachsen Formation, Axel Heiberg Island, Canadian High Arctic: in Analogs for planetary exploration (Garry, W. Brent, editor; et al.), Special Paper - Geological Society of America, 483, p. 249-261, illus. incl. sects., geol. sketch maps, 53 ref., 2011.
Recent orbital and rover missions to Mars have returned high-resolution images that show complex surface landforms in unprecedented detail. In addition, the spectral data sets from mission instruments reveal the presence of a wide array of mineral species on the surface of Mars. These discoveries are changing the analog science requirements of projects targeting exploration missions to Mars. Mission managers now expect field deployments to include complementary investigations of surface processes, rock types, mineral species, and microbial habitats. Earth-based analog sites are selected according to their potential for integrated geological and biological studies, wherein a central theme is the search for life. Geological field studies on Axel Heiberg Island, in the Canadian Arctic, demonstrate that the Isachsen Formation represents a high-fidelity analog for comparative studies of volcanic terrain on Mars. The two sites of interest are located in structurally complex zones (chaotic terrain) where basaltic lava flows, mafic dikes, and sandstone beds of Early Cretaceous age intersect evaporite outliers at the periphery of the diapirs. At the North Agate Fiord diapir and Junction diapir, remnant blocks of basaltic rock are pervasively altered and contain copper and iron sulfides, as well as the secondary sulfates copiapite, fibroferrite, and jarosite (North Agate Fiord diapir). Alteration zones within poorly consolidated quartzitic sandstone consist of thin layers of goethite, hematite, illite, and jarosite. The sites are morphologically different from Martian patera, but they provide access to volcanic successions and evaporites in areas of permafrost, i.e., conditions that are invoked in conceptual models for hydrothermal systems and groundwater flow on Mars.
12041510 Elberling, Bo (University of Copenhagen, Department of Geography and Geology, Copenhagen, Denmark); Christiansen, Hanne H. and Hansen, Birger U. High nitrous oxide production from thawing permafrost: Nature Geoscience, 3(5), p. 332-335, illus., 30 ref., May 2010. Supplemental information/data is available in the online version of this article; related article by Jungkunst, H. F., on p. 306-307.
12048142 Kjellstrom, Erik (Swedish Meteorological and Hydrological Institute, Norrkoping, Sweden); Brandefelt, Jenny; Naslund, Jens-Ove; Smith, Ben; Strandberg, Gustav; Voelker, Antje H. L. and Wohlfarth, Barbara. Simulated climate conditions in Europe during the Marine Isotope Stage 3 stadial: in Fennoscandian ice sheet in MIS 3 (Wohlfarth, Barbara, editor; et al.), Boreas, 39(2), p. 436-456, illus. incl. 2 tables, 84 ref., April 2010. Includes appendix.
State-of-the-art climate models were used to simulate climate conditions in Europe during Greenland Stadial (GS) 12 at 44 ka BP. The models employed for these simulations were: (i) a fully coupled atmosphere-ocean global climate model (AOGCM), and (ii) a regional atmospheric climate model (RCM) to dynamically downscale results from the global model for a more detailed investigation of European climate conditions. The vegetation was simulated off-line by a dynamic vegetation model forced by the climate from the RCM. The resulting vegetation was then compared with the a priori vegetation used in the first simulation. In a subsequent step, the RCM was rerun to yield a new climate more consistent with the simulated vegetation. Forcing conditions included orbital forcing, land-sea distribution, ice-sheet configuration, and atmospheric greenhouse gas concentrations representative for 44 ka BP. The results show a cold climate on the global scale, with global annual mean surface temperatures 5°C colder than the modern climate. This is still significantly warmer than temperatures derived from the same model system for the Last Glacial Maximum (LGM). Regional, northern European climate is much colder than today, but still significantly warmer than during the LGM. Comparisons between the simulated climate and proxy-based sea-surface temperature reconstructions show that the results are in broad agreement, albeit with a possible cold bias in parts of the North Atlantic in summer. Given a prescribed restricted Marine Isotope Stage 3 ice-sheet configuration, with large ice-free regions in Sweden and Finland, the AOGCM and RCM model simulations produce a cold and dry climate in line with the restricted ice-sheet configuration during GS 12. The simulated temperature climate, with prescribed ice-free conditions in south-central Fennoscandia, is favourable for the development of permafrost, but does not allow local ice-sheet formation as all snow melts during summer. Abstract Copyright (2010), The Boreas Collegium.
12040601 Creutzfeldt, Benjamin (German Research Centre for Geosciences, Section of Hydrology, Potsdam, Germany); Güntner, Andreas; Thoss, Heiko; Merz, Bruno and Wziontek, Hartmut. Measuring the effect of local water storage changes on in situ gravity observations; case study of the Geodetic Observatory Wettzell, Germany: Water Resources Research, 46(8), Citation W08531, illus. incl. 6 tables, sketch map, 74 ref., 2010.
Local water storage changes (WSC) are a key component of many hydrological issues, but their quantification is associated with a high level of uncertainty. High precision in situ gravity measurements are influenced by these WSC. This study evaluates the influence of local WSC (estimated using hydrological techniques) on gravity observations at the Geodetic Observatory Wettzell, Germany. WSC are comprehensively measured in all relevant storage components, namely groundwater, saprolite, soil, topsoil, and snow storage, and their gravity response is calculated. Total local WSC are derived, and uncertainties are assessed. With the exception of snow, all storage components have gravity responses of the same order of magnitude and are therefore relevant for gravity observations. The comparison of the total gravity response of local WSC to the gravity residuals obtained from a superconducting gravimeter shows similarities in both short-term and seasonal dynamics. A large proportion of the gravity residuals can be explained by local WSC. The results demonstrate the limitations of measuring total local WSC using hydrological methods and the potential use of in situ temporal gravity measurements for this purpose. Nevertheless, due to their integrative nature, gravity data must be interpreted with great care in hydrological studies.
12040629 Iwata, Yukiyoshi (National Agricultural Research Center for Hokkaido Region, Memuro, Japan); Hayashi, Masaki; Suzuki, Shinji; Hirota, Tomoyoshi and Hasegawa, Shuichi. Effects of snow cover on soil freezing, water movement, and snowmelt infiltration; a paired plot experiment: Water Resources Research, 46(9), Citation W09504, illus. incl. 1 table, 43 ref., 2010.
A dramatic reduction in soil frost depth has been reported for Hokkaido Island of northern Japan over the last 20 years. Since soil frost strongly affects snowmelt infiltration and runoff, the reduction in frost depth may have altered the water and nutrient cycles in this region. A paired-plot experiment was conducted in an agricultural field in Tokachi, Hokkaido, to compare the movement of soil water at different frost depths, controlled by manipulating the depth of snow cover. Snow was removed to enhance soil freezing in the treatment plot and was undisturbed in the control plot. The soil froze to a maximum depth of 0.43 m under the treatment plot and 0.11 m under the control plot. During the freezing period, the amount of upward soil water flux toward the freezing front in the treatment plot was more than double that in the control plot. During the snowmelt period, infiltration of meltwater was unimpeded by the thin frozen layer in the control plot, whereas the relatively thick frozen layer in the treatment plot impeded infiltration and generated 63 mm of runoff. These results clearly show that the changes in the timing and thickness of snow cover deposition can cause a dramatic reduction of frost depth and change in the soil water dynamics.
12042515 Jones, J. A. (Oregon State University, Department of Geosciences, Corvallis, OR) and Perkins, R. M. Extreme flood sensitivity to snow and forest harvest, western Cascades, Oregon, United States: Water Resources Research, 46(12), Citation W12512, illus. incl. 5 tables, 50 ref., 2010.
We examined the effects of snow, event size, basin size, and forest harvest on floods using >1000 peak discharge events from 1953 to 2006 from three small (<1 km2), paired-watershed forest-harvest experiments and six large (60-600 km2) basins spanning the transient (400-800 m) and seasonal (>800 m) snow zones in the western Cascades of Oregon. Retrospectively classified rain-on-snow events delivered 75% more water to soils than rain events. Peak discharges of >10 year rain-on-snow events were almost twice as high as rain peaks in large basins but only slightly higher in small basins. Peak discharges of >1 year rain-on-snow events increased slightly (10%-20%) after logging in small basins, but small basin peaks do not account for the magnitudes of large basin rain-on-snow peak discharges during >1 year floods. In extreme floods, despite very high infiltration capacity, high soil porosity, and steep hillslope gradients, prolonged precipitation and synchronous snowmelt produce rapid, synchronized hydrograph responses to small variations in maximum precipitation intensity. At the large basin scale, forest harvest may increase the area of snowpack and simultaneous snowmelt, especially in elevation zones normally dominated by rain and transient snow, thereby increasing large basin peaks without producing very large percent increases in small basin peaks. Further work is needed to describe water flow paths in melting snowpack, snow cover and the area experiencing snowmelt, synoptic peak discharges, and routing of flood peaks through the stream network during extreme rain-on-snow floods. The evolving structure of the forest on the landscape is a potentially very important factor influencing extreme rain-on-snow floods.
12040614 Mao, Dazhi (Purdue University, Department of Agricultural and Biological Engineering, West Lafayette, IN); Cherkauer, Keith A. and Flanagan, Dennis C. Development of a coupled soil erosion and large-scale hydrology modeling system: Water Resources Research, 46(8), Citation W08543, illus. incl. 5 tables, 50 ref., 2010.
Soil erosion models are usually limited in their application to the field scale; however, the management of land resources requires information at the regional scale. Large-scale physically based land surface schemes (LSS) provide estimates of regional scale hydrologic processes that contribute to erosion. If scaling issues are adequately addressed, coupling an LSS to a physically based erosion model can provide a tool to study the regional impact of soil erosion. A coupling scheme was developed using the Variable Infiltration Capacity (VIC) model to produce hydrologic inputs for the stand-alone Water Erosion Prediction Project-Hillslope Erosion (WEPP-HE) program, accounting for both temporal and spatial scaling issues. Precipitation events were disaggregated from daily to hourly and used with the VIC model to generate hydrologic fluxes. Slope profiles were downscaled from 30 arc second to 30 m hillslopes. Additionally, soil texture and erodibility were adjusted with simplified assumptions based on the full WEPP model. Soil erosion at the large scale was represented on a VIC model grid cell basis by applying WEPP-HE to subsamples of 30 m hillslopes. On an average annual basis, results showed that the coupled model was comparable with full WEPP model predictions. On an event basis, the coupled model system captured more small erosion events, with erodibility adjustments of the same magnitude as from the full WEPP model simulations. Differences in results can be attributed to discrepancies in hydrologic data calculations and simplified assumptions in vegetation and soil erodibility. Overall, the coupled model demonstrated the feasibility of erosion prediction for large river basins.
12043037 Valdés, H. (Catholic University of Concepcion, Clean Technology Laboratory, Concepcion, Chile); Godoy, H. P. and Zaror, C. A. Heterogeneous catalytic ozonation of cationic dyes using volcanic sand: Water Science and Technology, 61(12), p. 2973-2978, illus. incl. 4 tables, 24 ref., 2010.
This work aims to present experimental results on the treatment of methylene blue contaminated waters using heterogeneous catalytic ozonation promoted by volcanic sand. The effect of pH (2-8), and the presence of radical scavengers (acetate ions) in homogeneous and heterogeneous systems are evaluated at laboratory scale. Heterogeneous catalytic ozonation using volcanic sand increases methylene blue removal rate. In the presence of free radical scavengers, only a 37% reduction on methylene blue removal rate is observed in the heterogeneous system, as compared with 70% when homogeneous ozonation is used. The results obtained here indicate the importance of chemical surface properties on methylene blue oxidation reactions, suggesting that acid surface sites of volcanic sand play a key role on the reaction mechanism.
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12044784 Gislason, Sigurdur R. (University of Iceland, Institute of Earth Sciences, Reykjavik, Iceland) and Oelkers, Eric H. Silicate rock weathering and the global carbon cycle: in Frontiers in geochemistry; contribution of geochemistry to the study of the Earth (Harmon, Russell S., editor; et al.), Wiley-Blackwell, Chichester, United Kingdom, p. 84-103, illus. incl. 2 tables, 130 ref., 2011.
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12037626 Keller, Sarah J. Trends and interannual variability in snowpack and spring season hydroclimatology in the Southwest United States: 111 p., Master's, 2011, University of New Mexico, Albuquerque, NM.
12039398 Du, Enhao. Numerical simulation of the effect of land cover and climate changes on hydrological regimes in an inland Pacific Northwest watershed: 138 p., Doctoral, 2010, University of Idaho, Moscow, ID. ISBN: 978-1-124-42297-8 Available from: Univ. Microfilms.
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12039891 Abraham, J. D. (U. S. Geological Survey, Denver, CO); Minsley, B. J.; Cannia, J. C.; Smith, B. D.; Walvoord, M. A.; Voss, C. I.; Jorgenson, T. T.; Wylie, B. K. and Anderson, L. Airborne electromagnetic mapping of subsurface permafrost [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C51B-02, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Concerns over the impacts of climate change have recently energized research on the potential impacts thawing permafrost may have on groundwater flow, infrastructure, forest health, ecosystems, energy production, CO2 release, and contaminant transport. There is typically little knowledge about subsurface permafrost distributions, such as thickness and where groundwater-surface-water connections may occur through taliks. In June of 2010, the U.S. Geological Survey undertook an airborne electromagnetic (AEM) survey in the area of Fort Yukon, Alaska in order to map the 3-D distribution of permafrost and provide information for the development of groundwater models within the Yukon River Basin. Prior to the development of these models, information on areas of groundwater-surface water interaction was extremely limited. Lithology determined from a borehole drilled in Fort Yukon in 1994 agrees well with the resistivity depth sections inferred from the airborne survey. In addition to lithology, there a thermal imprint appears on the subsurface resistivity values. In the upper 20-50 m, the sections show continuous areas of high electrical resistivity, consistent with alluvial gravel deposits that are likely frozen. At depth, unfrozen gravel deposits have intermediate-to-high resistivity; frozen silts have intermediate resistivity; and unfrozen silts have low resistivity. Under the Yukon River and lakes where the subsurface is not frozen, zones of moderate resistivity intermix with areas of low resistivity. The areas of loess hills on the margins of the Yukon Flats have very-high electrical resistivity, indicating higher ice content, and are associated with the some of the greatest thickness of permafrost in the survey area. This work provides the first look into the 3-D distribution of permafrost in the areas around Fort Yukon and is a demonstration of the application of AEM to permafrost mapping. The AEM survey provides unprecedented 3-D images of subsurface electrical properties that reveal changes in lithology and the presence or absence of permafrost. These geophysical data fill an important gap between sparsely sampled boreholes, regional hydrogeologic measurements, and remote sensing data. Interpretations of the AEM data are being integrated with other remotely sensed data to supply critical hydrogeological information needed for developing an improved understanding of groundwater-surface-water interactions in permafrost terrains. More specifically, the interpretations of the AEM data help to refine groundwater flow models in the Yukon Flats Basin. Because of the success of this study we now know that there are many other uses for this data. For example, airborne surveys can provide baseline data for estimating the 3-D distribution of permafrost that can be compared to future surveys in order to estimate volumetric changes over time.
12047498 Anisimov, Oleg A. (State Hydrological Institute, St. Petersburg, Russian Federation); Lavrov, S. A. and Borzenkova, Irena I. Methane emission from sub-sea permafrost in the East Siberian Arctic shelf; model-based evaluation of potential impact on global climate [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C21D-06, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
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 in the period 1985-2009 and subsequent deepening by 5 m after 50 years, ~9 m after 100 years, and ~48 m after 1000 years. Over the same time periods, the control runs without BLT trends show a deepening of the permafrost table by 0.1 m, 0.2 m, and 2 m, respectively. These results do not support the hypothesis of recent increase in permafrost permeability due to formation of taliks. The high CH4 concentration over the ESS is more likely to be attributed to the long lasting degradation of subsea permafrost initiated 8 KY ago. Our estimates based on the analysis of the greenhouse gas potential indicated that if the current conditions with ca. 7.9 Tg/y CH4 flux from ESS area to the atmosphere persist for the following decades, it may increase the atmospheric concentration of methane by ca. 0.04 ppm. The associated radiative forcing will lead to less than 0.015°C global temperature rise, which is insignificant compared to the effect of other factors governing the modern climate change.
12047557 Arp, C. D. (University of Alaska Fairbanks, Water and Environmental Research Center, Fairbanks, AK); Jones, B.; Urban, F. E.; Grosse, G. and Whitman, M. Shifting ice regimes of Arctic thermokarst lakes and implications for permafrost and surface-water dynamics [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C31B-02, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Thermokarst lakes cover >20% of the landscape throughout much of the Arctic Coastal Plain (ACP) of northern Alaska with shallow lakes freezing solid (grounded ice) and deeper lakes maintaining perennial liquid water (floating ice). Thus, lake depth relative to maximum ice thickness represents an important threshold that impacts permafrost, aquatic habitat, and potentially geomorphic and hydrologic behavior. We studied coupled hydrogeomorphic processes of 13 lakes in the Teshekpuk Lake Special Area (TLSA) representing a depth gradient across this threshold of maximum ice thickness by analyzing remotely sensed imagery, water quality surveys, and climatic data over a 35-year period. Shoreline erosion rates due to permafrost degradation ranged from <0.2 m/yr in very shallow lakes (0.4 m) up to 1.8 m/yr in the deepest lakes (2.6 m) and appear to be partly linked to variation in mean annual lake temperature (MALT). This pattern of thermokarst expansion masked detection of lake hydrologic change using remotely sensed imagery except for the shallowest lakes with stable shorelines. Changes in the surface area of these shallow lakes tracked interannual variation in precipitation minus evaporation (P-E) with periods of full and nearly dry basins. Our analysis suggests that grounded-ice lakes are ice-free on average 37 days longer than floating-ice lakes resulting in a longer period of evaporative loss and more frequent negative P-E. These results suggest divergent hydrogeomorphic responses to a changing Arctic climate depending on the threshold created by water depth relative to maximum ice thickness in ACP lakes. With respect to these findings there is particular interest in ACP lakes of depths encompassing the range of interannual variation in maximum ice thickness because these lakes will most readily show a shift of ice regimes with either a change in water balance or ice growth. For instance, a positive summer P-E and slow winter ice growth can result in a higher proportion of lakes with floating ice regimes. Such a regime shift from grounded-ice to floating-ice could result in enhanced shoreline permafrost degradation and the accelerated development of taliks and corresponding decomposition of organic matter in thawing sediments, as well as later ice-out and lower lake evaporation. A collection of mid-spring ice thickness measurements from TLSA lakes range from 1.9 to 2.3 m in the late 1970's and 1.3 to 1.7 m during the last 5 years (2007-11). To better understand the impact of variation in maximum ice thickness among ACP lakes, we compared 2009-10 with moderate ice thickness (1.6 m) to 2010-11 with thin ice thickness (1.3 m). We examine differences in MALT and ice-out timing among a set of lakes on the ACP to gauge how sensitive lakes near the maximum ice-thickness threshold are to such interannual variation and a potential trend towards greater summer P-E and reduced winter ice growth due to both warmer temperatures and higher snowfall.
12047505 Bateni, S. (University of California at Los Angeles, Los Angeles, CA); Huang, Chunlin; Margulis, S. A.; Podest, E. and McDonald, Kyle C. Feasibility of monitoring freeze-thaw state of soil underlying snowpack using multifrequency active/passive microwave measurements [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C22B-03, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
An ensemble-based data assimilation (DA) model is developed in order to characterize the freeze-thaw state of soil underneath a seasonal snowpack using multifrequency passive and active microwave remote sensing measurements. The feasibility of the DA model in estimating the soil freeze-thaw state (including soil surface temperature and both ice/water content) is tested within a season-long, point-scale synthetic experiment. Synthetic passive microwave observations at 1.4, 18.7, and 36.5 GHz frequencies and synthetic active microwave observations in L-band (1-2 GHz) and Ku-band (10.95-14.5 GHz) are assimilated individually and simultaneously in order to update the soil freeze-thaw state available from a land surface model using an Ensemble Single Batch smoother (EnSB) framework. The contribution of each channel in retrieving the true land surface temperature and soil water/ice content is investigated. The results indicate that the new methodology provides an ideal basis for exploring the intricate relationships between the soil freeze-thaw state and the remote sensing measurements, and enables us to use implicit information contained in the remotely sensed observations to estimate the soil freeze-thaw state. It is found that all of the utilized passive microwave frequencies (1.4, 18.7, and 36.5 GHz) contain a significant amount of information for characterizing the freeze-thaw state of soil underneath a snowpack with the lowest-frequency channel (i.e., 1.4 GHz) being most effective. Also, both of the active microwave bands (L- and Ku-bands) significantly contribute to recovering the true soil freeze-thaw state. Finally, results from the simultaneous assimilation of passive and active microwave observations are compared to those from a pure modeling approach. Our results suggest that assimilating both passive and active microwave observations significantly decreases the errors associated with the pure modeling approach. The results have implications for monitoring freeze-thaw state in conjunction with existing and future satellite missions including AMSR-E, SMAP, and CoREH20.
12039880 Engram, Melanie J. (University of Alaska Fairbanks, Department of Water and Environmental Research, Fairbanks, AK); Walter Anthony, K.; Meyer, F. J. and Grosse, G. Quantifying methane ebullition in thermokarst lakes with space borne synthetic aperture radar (SAR) [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C43B-02, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Northern high latitude wetlands and thermokarst lakes in permafrost regions have been identified as strong sources for methane (CH4), a powerful greenhouse gas. Quantifying the spatial distribution and magnitude of CH4 sources in these regions has become increasingly important in the current scenario of global warming and amidst concerns of partial release of the large permafrost soil carbon pool through thawing by thermokarst lakes. Ebullition (bubbling) is an important mode of CH4 emission from thermokarst lakes to the atmosphere. However, due to its sporadic behavior, large uncertainties remain in estimating the magnitude of ebullition emissions from lakes. Synthetic Aperture Radar (SAR) remote sensing of lake ice is a potentially valuable tool to constrain bottom-up estimates of lake ebullition in regions where lake ice forms. Here we explored various SAR imaging parameters as they correlate to field measurements of CH4 ebullition bubbles in the ice of ten thermokarst lakes on the northern Seward Peninsula, Alaska. We found that ebullition bubbles trapped in frozen lakes were strongly correlated with L-band single polarized horizontal (HH) SAR (R2=0.70, P=0.002) and with the 'roughness' component of a classic Pauli decomposition of PALSAR L-band quad-polarized signal (R2=0.77, P=0.001). We found no such correlation with ERS-2 C-band single polarized vertical (VV) SAR. We present the results of our single-pol and quad-pol SAR geospatial analysis, a discussion of probable scattering mechanisms of ebullition bubbles in frozen thermokarst lakes and our recommendation for the optimal season for SAR observation. Our results indicate that calibrated L-band SAR could be a valuable tool for estimating methane ebullition in lakes on a regional scale by evaluating the backscatter intensity from early winter lake ice.
12047548 Herman, Bruce M. (BOEMRE, Resource Evaluation, Anchorage, AK). The distribution of permafrost beneath the Beaufort Sea continental shelf [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C31A-0590, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
The entire Beaufort Sea continental shelf (CS) is generally believed to have been sub-aerially exposed to temperatures of -12°C during the sea level low-stand that accompanied the last glacial age. After inundation due to rising sea level, the temperature of the seafloor would have been near 0°C. Permafrost formed prior to flooding was generally expected to be ubiquitous at depth due to the relatively recent time of inundation. Seaward of just beyond the Beaufort Sea barrier islands, downhole resistivity and sonic logging in the 10 hydrocarbon exploration wells that have logging at least as shallow as 300 m below sea level (BSL) has not demonstrated evidence of ice-bearing permafrost (IBPF). Indirect evidence of IBPF seaward of the barrier islands is limited to the Belcher well on the eastern Beaufort CS where rock containing gas hydrate was blown from the well while drilling at 754 m BSL (Exlog Canada, 1988). A bottom simulating reflection is observed on the multichannel seismic reflection (MCS) data near the location of the Belcher well, confirming the presence of gas hydrate. From the barrier islands shoreward to the coast, IBPF is indicated by resistivity and sonic logs in all wells having data. The depth to the base of the permafrost in the near shore and onshore areas varies from 200 m to over 600 m. Where the top and bottom of the IBPF are observed in the resistivity logs on the barrier islands, the thickness ranges from 100-300 m. MCS data have been collected on the Beaufort CS by the oil industry since the 1970's. IBPF may be inferred from maps of the Dix average velocity (Vave) at a travel time somewhat deeper than the anticipated depth to its base, e.g., 0.75 sec two-way-travel (TWT). Vave is 2.4-3.0 km/sec onshore. In the western Beaufort, Vave decreases rapidly across the shoreline and out to the barrier islands, beyond which it is relatively constant at 1.8 km/sec out to the shelf edge. Vave decreases across the shoreline in the eastern Beaufort, too, although not as abruptly, where it ranges from 1.8 to 2.0 km/sec over distances of 10 km or more. The variations in Vave, whether across the shoreline or from east to west on the Beaufort CS do not correspond to structure observed in the MCS data, but do correlate roughly with IBPF presence in the well data. Reflection velocity profiles themselves may indicate IBPF at depth in the offshore when anomalously high stacking velocities (Vstk) are detected in the upper half second of TWT. Vstk of approximately 2.7 km/sec at 0.25 sec TWT decreases to 2.3 km/sec at roughly 1 sec TWT in areas where IBPF is suspected based on well log data or mapped Vave. Away from such areas, observed shallow Vstk are more typically about 1.8 km/sec. The interpretation of stacking velocity data is somewhat subjective, but shoreward of the barrier islands, most stacking velocity profiles exhibit inversions in the upper 1 sec TWT. Outboard of the barrier island on the western Beaufort CS inversions are rare. They are more frequent on the eastern Beaufort CS. IBPF is common on the Beaufort CS between the coast and the barrier islands. Seaward of the islands, it appears to be nearly absent on the western Beaufort CS and more common on the eastern shelf.
12039938 Herman, R. B. (Radford University, Department of Physics, Radford, VA) and Palmer, J. GPR studies at the Nuvuk burial site at Point Barrow, Alaska [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract NS51A-1738, illus., December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Ground penetrating radar was used to study a portion of the Nuvuk (Thule people) prehistoric burial site and to search for a buried prehistoric strand line at Point Barrow. GPR operating at 500 MHz resolved features up to 2.5 m deep in this area and were used to aid in search and recovery efforts. These scans imaged areas of recent disturbance that required shovel testing to confirm the lack of burials. This survey was able to rule out burials in several areas. Scans determined at least one area where a burial was found that would have been too deep for normal shovel tests to detect. A nearby area was scanned to trace the path of a prehistoric strand line whose initial presence had been revealed by exposure on the bluff adjacent to the Beaufort Sea. The GPR data revealed the path of that strand line along with a number of others. Final GPR images and GPS maps of the survey areas and the strand lines will be presented. The results of follow-up excavations will be discussed, along with the GPR parameters that gave the best results.
12047553 Kasurak, A. (University of Waterloo, Department of Geography, Waterloo, ON, Canada); King, J. M. and Kelly, R. E. Characterising volume scatter in snow covered organic soils in the tundra using ground-based scatterometers at Ku- and X-band frequencies [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C31A-0608, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Shallow snow is widespread in the tundra and plays an important role in the energy and mass balance of the cryosphere. Its extent and quantity are important to for climate model simulations and hydrological forecasting. Active microwave (MW) remote sensing is an ideal tool for local to regional scale snow water equivalent (SWE) estimation in these cloud dominated regions. SWE retrieval approaches using scatterometers have applied radiative-transfer models, such as the semi-empirical HUT model, with some success. For active remote sensing of snow the state of the background media modifies the observed signal and strongly influences the emission or backscatter from the snow. In the estimation of tundra SWE, peat and highly organic soils, which are found in this region, are often not well represented in the standard soil emission and backscatter models which are parameterized by more mid to low latitude mineral soil types. In its frozen form, peat has proven to have very different MW properties than mineral soils. Continuous variation in the received signal of an active MW system operating at the X-band was observed in Sodankyla, Finland until the soil froze to a depth of 0.5-1 m. Similar sub-nivean soil freezing effects have been found in observations made in Churchill, Canada during the 2010-2011 winter season using an active MW system at X (9.6 GHz) and Ku (17.2 GHz). Quantifying or resolving this uncertainty is important for potential future space-borne missions such as the Cold Regions Hydrology High-resolution Observatory (CoReH2O), a candidate European Space Agency Earth Explorer mission. This study presents a modified snow retrieval model, where the standard ground reflection component is replaced with three candidate soil backscatter mechanisms: 1) peat as a homogeneous volume scatterer with a basal reflector to indicate the unfrozen (water table) surface; 2) peat as a layered volume scatterer to reflect the differences between low density living vegetation and high density decomposed material, with a similar lower reflection boundary; 3) peat as an optically thick volume scatterer. The candidate models are run with each of the three soil backscatter mechanisms to simulate the observed backscatter, and are parameterized and forced using in situ snow pit and soil measurements. Comparison of the simulated backscatter estimates with scatterometer observations provide useful information on the the role of each mechanism.
12039937 Kuras, O. (British Geological Survey, Geophysical Tomography, Nottingham, United Kingdom); Krautblatter, Michael; Murton, J. B.; Haslam, E.; Wilkinson, P. and Meldrum, P. Time-lapse capacitive resistivity imaging; a new technology concept for the monitoring of permafrost [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract NS51A-1737, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
We have investigated and sought to prove a new technology concept for the non-invasive volumetric imaging and routine temporal monitoring of the thermal state of permafrost, a key indicator of global climate change. Capacitive Resistivity Imaging (CRI), a technique based upon low-frequency, capacitively-coupled measurements across permanently installed multi-sensor arrays is applied in order to emulate Electrical Resistivity Tomography (ERT) methodology, but without the need for galvanic contact on frozen soils or rocks. Recent work has shown that temperature-calibrated ERT using galvanic sensors is capable of imaging recession and re-advance of rock permafrost in response to the ambient temperature regime. However, our own laboratory experiments on rock samples under simulated permafrost conditions have equally demonstrated that galvanic electrodes experience large variations in contact resistances between sensors and the host material as the active layer freezes and thaws, leading to a rapid deterioration of data quality over time. As the presence of systematic but uncontrolled sensor noise will reduce the value of time-lapse ERT datasets for monitoring permafrost, the use of galvanic sensors will invariably impose practical limitations on field measurements. The capacitive methodology we are presenting here overcomes this problem and provides a roadmap for making stable resistance measurements with permanently installed sensors over time. We report on our experience with designing, building, testing and validating a functional prototype time-lapse CRI measurement system. The practical system architecture draws upon conceptual ideas incorporated in existing, field-scale CRI instrumentation designed by BGS; however, the use of dense capacitive sensor networks at the laboratory scale and the need for collecting tomographic imaging data across multiple sensors in an automated fashion required a novel technical approach. Our research has applied 4D CRI as well as conventional ERT to controlled laboratory experiments simulating permafrost growth, persistence and thaw in bedrock. We have used the Permafrost Laboratory at the University of Sussex, a facility specifically designed to carry out large-scale rock freezing experiments. Water-saturated samples of limestone and chalk (450 mm high, 300 mm´300 mm wide) of varying porosity are being monitored. The lower half of each sample is maintained at temperatures below 0°C (simulating permafrost) and the upper half is cycled above and below 0°C (simulating seasonal thawing and freezing of the overlying active layer). Samples are instrumented with both capacitive and conventional galvanic sensor arrays, allowing us to compare results between both resistivity methods. Time-lapse imaging of the samples during successive freeze-thaw cycles of the active layer is testing the functionality of the prototype instrumentation and provides representative CRI and ERT datasets. Experimental control and calibration of the resistivity images is being provided by simultaneous temperature and moisture content measurements on the samples.
12039879 Kuznetsov, D. E. (Moscow State University, Laboratory of Geoecology of the North, Moscow, Russian Federation); Belova, Nataliya; Noskov, Alex and Ogorodov, S. Implementation of remote sensing data in research of coastal dynamics at the Baydaratskaya Bay, Kara Sea [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C43B-01, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
The development of Arctic coastal regions is now in progress due to significant amount of hydrocarbon deposits discovered. In high latitudes, natural hazards such as coastal erosion and thermoerosion, deflation, linear erosion and thermal denudation, ice gouging can make petroleum production and transport unprofitable. A prominent feature of Kara Sea, as well as other Arctic seas, is the development of coast in permafrost conditions. Despite the long ice period (up to 9 months), during the ice free period coastal dynamics are very intensive. If pipeline landfall site occurs at a shore section with high retreat rate (1-3 m/year and higher), danger of pipeline damage due to exposure, line sagging and mechanical deformations becomes high. Protective measures may appear inefficient, since shore sections with active coastal erosion are subject not only to bluff retreat, but also to nearshore zone and coastal slope erosion. Exposed pipeline sections also get in danger of sea ice effect. For correct definition of coastal dynamics setting we use dual approach. The first part is perennial instrumental monitoring of shore morphology, relying on system of benchmarks used for repeated measures, together with in-field geomorphologic expertise. Measures include direct observations and geodetic leveling onshore and echosounding offshore. Being the most precise method, direct measurements are expensive. The other drawback is that they can't give an overview of long-span tendencies of coastal evolution for prolonged shore sections, which is essential for shore deformation forecast complying with lifetime of structures (usually 30 to 50 years). This is where the importance of the 2nd part, analysis of the different time remote sensing data, becomes decisive. Most important sources of remote sensing data include Corona imagery from 1960s-70s, aerial photos of different times (but most of them are inaccessible for Russian Arctic coast), Landsat imagery (covering a long time span, detailed enough for preliminary analysis, free for significant part), Ikonos, QuickBird, and other modern high-resolution imagery. Georeferencing is taken from State topographic and bathymetric maps and high resolution imagery (corrected by field GPS survey where possible). All data are aligned and catalogued with ArcGIS. Corona and aerial images must be aligned thoroughly with use of high-resolution data as reference, placing control points on most stable topography (gully junctions, inter-lake channels, river heads), which are vectorized in advance. Shoreline is usually easily recognizable for both erosion and accumulation sections of the coast. Other distinct features include alongshore bars, thermokarst basins, deflation sites. Basing on above-mentioned analysis, coastal dynamics maps were created for time span long enough to ensure shore dynamics forecasts. For the coast of Baydaratskaya Bay, Kara Sea, the maps cover period from 1964 to 2009. Further steps include creation of shore classification and segmentation maps, which consider different features of coastal morphology, dynamics, and formation taken from both field investigations and remote sensing data analysis. This work was supported by Sustainable Arctic Coastal and Marine Technology (SACME) Project.
12047558 Langer, M. (Alfred Wegener Institute, Potsdam, Germany); Westermann, Sebastian; Abnizova, Anna; Muster, Sina; Wischnewski, Karoline and Boike, J. The freeze-up of High Arctic ponds and potential impacts on the carbon balance [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C31B-03, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
A considerable part of the global carbon budget is stored in the Arctic permafrost landscapes. Several studies suggest that lakes and ponds play a key role in the carbon turnover of these ecosystems as they are considered to be favourable paths of carbon exchange between surface and atmosphere. The direction and strength of the carbon fluxes from Arctic lakes is controlled by a variety of physical and biochemical processes whose climate interactions are complex and still poorly understood. In some Arctic regions the fractional area of lakes and ponds can be as large as 25% highlighting the importance of water bodies in the Arctic ecosystems. Our long-term studies on the energy balance of a typical Arctic lake landscape reveal that the seasonal freeze-thaw dynamic is highly sensitive to small variations in the winter time radiation budget and the subsurface heat flux, especially at shallow ponds. The time required to completely freeze the water body including the subjacent bottom sediments can vary up to several months. This implies that the period of unfrozen ponds, during which biological activity is favourable, highly depends on factors such as the winter time cloudiness and snow cover. Hence, the close interaction between the winter time surface energy balance and biological processes might strongly affect the production and storage of green house gases of Arctic landscapes. This potential climate feedback mechanism is even more important as small water bodies are usually below the spatial resolution of remote sensing products. Therefore, they are not included in landscape classifications used in recent estimates of the global carbon budget or climate models. Nevertheless, small water bodies can make up a considerable percentage of the tundra surface comparable in size to the area occupied by large (thermokarst) lakes. Further investigation on the role of small water bodies appears to be mandatory for a better understanding of the Arctic carbon balance.
12047559 Lesack, L. (Simon Fraser University, Department of Geography and Biological Sciences, Burnaby, BC, Canada); Tank, S. E.; Gareis, Jolie; Chateauvert, C. A.; Squires, Maggie and Marsh, Philip. Functional carbon processing and its linkage to hydrology in lakes of the Mackenzie River delta [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C31B-05, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
The circumpolar arctic contains a number of large river deltas that are lake-rich because of thermokarst effects. The Mackenzie Delta is the second largest, containing 45,000 lakes within a floodplain area 1/3rd the size of Switzerland. A 20-year case study has placed the biogeochemistry of these lakes into context via analysis of 40 years of water level records, river-to-lake connectivities, and estimates of annual river-water renewal. The lakes collectively represent gradients from turbid waters to transparent, high dissolved-nutrients to low, low total dissolved organic matter (DOM) to high, high chromophoric-DOM (CDOM) to low, high inorganic content of lake sediments to high organic sediment, and low under-water ultraviolet-irradiance to higher irradiances. Super imposed on these are biotic community production gradients respectively ranging from low production of aquatic bacteria to high, low macrophytes to high, low epiphyton to high, high phytoplankton and epipelon at intermediate flooding-frequencies, low small-bodied zooplankton to high large-bodied, high fish to no fish, and moderate aquatic birds to high. All the above correspond with a gradient of lake flooding regimes with average river-to-lake connection times ranging from >150 days per year in the lowest elevation lakes maintaining near continuous connection with the river over the open-water period to <4.5 days per year in the highest elevation lakes with long and variable disconnection periods from the river. Thermokarst lakes and lake-chain systems represent special cases where lake behaviors may depart from patterns otherwise strongly linked to river-to-lake connection times. Based on work in this system thus far, we propose a new conceptual model of overall carbon processing based on functional groups of organisms and abiotic processes that govern the overall balance between recycling of carbon to the atmosphere as CO2 or CH4, or the accumulation and storage of carbon in lake biomasses, and which encompasses the full range of carbon flow configurations identified thus far in Mackenzie Delta lakes. Our model distinguishes sub-configurations for 6 specific lake-types. In order of increasing water transparency, these include: (1) turbid no-closure lakes, (2) turbid low-closure, (3) clear no-closure members of lake chains, (4) clear low-closure, (5) thermokarst high-closure, and (6) clear high-closure lakes. The model also discriminates among 6 specific interlinked subsystems - (a) lakewater supply of dissolved inorganic carbon, (b) allochthonous supply of CDOM and its photochemistry, (c) the autotrophically supported foodweb, (d) the DOM supported microbial foodweb, (e) inorganic formation of organic particles from DOM, and (f) carbon recycling via methanogenic and methanotrophic bacteria. The total number of important flux pathways in our model is large (=44) and the overall balance of fluxes and their uncertainties is important for understanding the response of this large arctic delta to global change and its potential role in the composition of Mackenzie River nutrient and carbon fluxes to the Arctic Ocean.
12047560 Maard Karlsson, Johanna (Stockholm University, Department of Physical Geography & Quaternary Geology, Stockholm, Sweden); Lyon, Steve W. and Destouni, Georgia. Arctic hydrology shifts with permafrost thawing and thermokarst lake changes [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C31B-07, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
The continuous to sporadic permafrost that underlies the tundra and taiga landscapes of the Nadym (48,000 km2) and Pur (95,100 km2) river basins in northwestern Siberia has been warming significantly during the recent decades, similarly to numerous other river basins across the Arctic. We hypothesized that permafrost thawing, which directly influences the formation/drainage of thermokarst lakes, also causes other detectable hydrological changes in Arctic river basins. To test this in the Nadym and Pur river basin cases, we mapped their thermokarst lake distributions using remote sensing analysis, determined their rainfall-runoff relations using available monthly precipitation and discharge data, and assessed the changes in both of these hydrological aspects from 1973, through 1987-88, to 2006-2010. The results show both development of new thermokarst lakes and drainage of existing ones, in conjunction with substantial changes in seasonal hydrology. Specifically, the number and total area of thermokarst lakes increased between 1973 and 1987-88, and then decreased between 1987-88 and 2006-10 in both basins. During these thermokarst lake changes, summer discharge increased while summer precipitation decreased in the Pur basin, with the Nadym basin exhibiting a similar change pattern in the autumn season, and both river basins having stable winter discharges while their winter precipitation increased. In addition, both basins had decreasing discharge variability, indicating substantial changes in their hydrological storage-discharge dynamics as a result of the permafrost thawing that also changed their thermokarst lakes. These hydrological shifts may impact vegetation patterns and biogeochemical cycling through changed rates of carbon and nutrient fluxes, which can ultimately also feed back to climate change.
12039893 Miceli, Christina M. (University of Ottawa, Department of Geography, Ottawa, ON, Canada) and Lewkowicz, A. G. Seasonal cycling in electrical resistivities at thin permafrost sites, southern Yukon and northern British Columbia [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C51B-04, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Ten research sites located in the zones of sporadic discontinuous permafrost and isolated patches of permafrost were instrumented for active layer temperature, air temperature, and snow depth monitoring along a 1200 km length of the Alaska Highway east of Whitehorse. A permanent Wenner array was established at each site in order to undertake repeated surveys of DC electrical resistivity tomography (ERT). This geophysical method has been used in North America as a means to obtain an instantaneous view of permafrost conditions (e.g. Lewkowicz et al., 2011). However, research in the European Alps (e.g. Isaksen et al. 2011) has shown that multiple re-surveys can be used to examine changes in frozen ground conditions over longer time-spans. The central objective of this work is to determine what changes in thin permafrost and seasonally frozen ground in unconsolidated sediments can be detected by ERT over an annual cycle of freezing and thawing. Resistivity surveys were conducted in August 2010, and in March, May, June and July 2011. A further survey will be undertaken in August 2011. Inversion of the field readings to date revealed three layer systems in thin permafrost at all but one of the ten sites. At all sites, the active layer and upper permafrost experienced the most seasonal change in resistivity due to the high amplitude temperature change and hence alteration in unfrozen moisture content. At site MP400, for example, resistivities in the top 0.5 m increased on average by 78%, between August and the following March, when temperatures at 50 cm decreased from 2.0 to -0.6°C (Figure 1A). At a depth of 10-11 m, the same seasonal pattern was evident but the average change was only 34% (Figure 1B).
12039939 Monnier, Sebastien (Centro de Estudios Avanzados en Zonas Áridas, La Serena, Chile); Bodet, Ludovic; Camerlynck, Christian M.; Dhemaied, Amine; Galibert, Pierre; Kinnard, C.; Vitale, Quentin and Saéz, Rodrigo. Advanced seismic and GPR survey of a rock glacier in the upper Choapa Valley, semi-arid Andes of Chile [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract NS51A-1739, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
In semi-arid to arid contexts, rock glaciers, as other prominent permafrost features, can represent critical permanent resources of solid water. It is thus important to analyze their internal structure and estimate their ice content, especially in mining areas where human activities may have an impact on permafrost features. In the upper Choapa Valley, semi-arid Andes of Chile (31.59°S, 70.50°W), we investigate a small rock glacier located in an open-pit copper mine, using data from two boreholes and advanced geophysical methods. The two boreholes, performed using diamond drill hole technique, reveal relatively low ice content (order of magnitude: 20-25%) in the rock glacier. Seismic and ground-penetrating (GPR) radar surveys were performed on the surface of the rock glacier. P- and S-wave refraction seismics were employed along two profiles. The ground-penetrating radar operation mode was quite new and innovative for a rock glacier site; it consisted, (1) for three-dimensional imaging, of a rectangular grid of 25 evenly (2 m) spaced constant-offset (2 m) profiles, and (2) for velocity analysis, of a 150 m-long profile performed many times in constant-offset mode with offset varying between 0.5 and 16 m. The processing of the acquired data permits to obtain an accurate representation of the internal structure and an estimation of the overall ice content in the rock glacier.
12047561 Potter, B. L. (University of Nebraska-Lincoln, Department of Natural Resources, Lincoln, NE); Lenters, J. D.; Hinkel, Kenneth M.; Shulski, M.; Healey, Nate C.; Irmak, A.; Jones, S. L. and Sheng, Y. The summertime energy balance of a thermokarst lake in northern Alaska; a three-year study of seasonal and interannual variability [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C31B-08, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Shallow, thermokarst lakes--which develop atop permafrost--are a prominent landscape feature on the Arctic Coastal Plain (ACP) of northern Alaska. The ACP is vulnerable to ongoing climate change and landscape modification, as thousands of thaw lakes and ponds are impacted by changes in temperature, precipitation, thawing permafrost, and human activity. Although summer in the Arctic is short, incoming solar radiation and lake evaporation are relatively high, and both factors play a significant role in the landscape water balance. Furthermore, lake evaporation is anticipated to increase as the ice-free season lengthens and water temperatures become warmer. To improve our understanding of these processes, we performed a multi-year energy balance analysis of a thermokarst lake near Barrow, Alaska. The lake is about 4 km from the Arctic coast, and is relatively small having an area of 185.7 Ha. Timeseries of net radiation, Bowen ratio, and the rate of lake heat storage (at hourly, daily, and longer timescales) were used to calculate sensible and latent heat fluxes during the 2008-2010 ice-free periods (roughly early July through late September). Sediment heat flux estimates were included in the calculation of the total heat storage rate and were determined from a simple heat flux model (calibrated using numerous measurements of thermal conductivity and temperature gradient in the lake sediment). Hourly shortwave albedo measurements were collected during a 23-day period in 2008 to generate a diurnal albedo curve, which was found to range from roughly 0.06 in late morning to 0.17 in late evening. Results of the energy balance analysis show rapid warming of the lake water and sediments immediately following ice-off (due to high insolation), followed by similar increases in sensible and latent heat flux. Bowen ratios were typically around 0.7-1.1, indicating that the majority of the available energy was consumed by lake evaporation, which averaged around 1.3 mm/day during the ice-free period (i.e., nearly twice the mean summertime precipitation rate of 0.7 mm/day for Barrow, Alaska). Daily evaporation rates ranged from zero to greater than 4 mm/day, while seasonal patterns varied significantly from one year to the next. Much of this variability was associated with changes in cloud cover, water temperature, relative humidity, and wind speed. The mass-transfer technique was also used to provide supplementary estimates of latent and sensible heat flux, and these estimates were found to agree well with the energy balance calculations.
12039899 Przyklenk, A. (Technical University of Braunschweig, Braunschweig, Germany); Hördt, A. and Lippmann, E. A prototype device to measure complex resistivity based on capacitive coupling [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract NS33B-1591, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
The basic concept of all electrical methods is to couple a transmitter signal into the ground and to measure the response with a receiver. This can be realized in two different ways. First, galvanic coupling can be used, which implies static or low-frequency fields (max. 10 Hz) and a dominant direct current. In this case the main information is the in-phase transfer impedance and hence the resistivity. The second way to feed a current into the ground is capacitive coupling. Possible electrodes are plates or cables that are in a defined distance to the surface and do not need galvanic contact. Due to accumulated charges, an electrical field between the electrodes and the ground provides the coupling similar to a capacitor. The frequency range is limited by high contact impedances at low frequencies and inductive coupling at high frequencies. It is technically feasible to measure made grounds, dry and solid soils or permafrost that go along with high resistivities up to 10 MWm. The prototype is based on capacitive coupling and works with four different frequencies in the range of 100 Hz to 90 kHz. A total of four settings for the internal resistance of the transmitter allow resistance measurements from 10 W to 10 MW. A lock-in amplifier, that is part of the receiver, is used to measure the fully complex transfer impedance. In addition to the impedance of a 4-point configuration, the contact impedance of the electrodes can be measured. To calibrate the instrument, dipole-dipole transfer impedances and contact impedances were calculated for a variety of field parameters like resistivity, permittivity, frequency and geometry. Based on the calculations, extensive calibrations were made with analog circuits. The range of applicability and the limitations are investigated with test measurements in the laboratory under controlled conditions in a sand filled 1.2 m´1.2 m box. The results are assessed based on a comparison with DC-measurements at low frequencies.
12047586 Raab, T. K. (Stanford University, Department of Biology, Stanford, CA); Crook, N. P. and Lipson, D. Electromagnetic and chemical characterization of Arctic coastal tundra soils [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C33A-0626, 3 ref., December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
We have argued previously that the dissimilatory Fe-reduction is a key anaerobic process in Arctic Coastal Plain soils formed in drained thaw-lake basins. These peat-accreting landforms vary in age from contemporary to 5500 yrs BP, with increasing age of basin hypothesized to increase the distance between the active layer and the underlying mineral horizons. We characterized the electromagnetic properties by radar, spin-resonance characteristics, and magnetic susceptibility profiles of basins differing in age. Most sites demonstrated surface-enhancement of magnetic susceptibility (cLF), with the OM-free values in Old Basins (the most abundant age-class near Barrow AK) in excess of 11´10-5 (m3 kg-1 SI), and max values at depths of 4-22 cm. Total soil susceptibility appeared to decrease in younger basins. This was curious, since 1M HCl-extractable Fe indicated generally lower [Fe] availability as soils develop. To understand the nature of the local paramagnetic minerals, we compared LN2-temp ESR on freeze-dried soils of differing age. Electron spin resonance spectra demonstrated two principal spectral features: (1) an organic free-radical signature near the free-e- value of g~2.0023, and (2) iron-spin transitions within rhombohedral complexes at g~4.2-4.3. At depth, the organic free-radical signatures demonstrated noticeable hyperfine-splitting from a spin S=5/2 nucleus, most likely a covalent association with iron. If iron and humic substances serve as alternative electron-acceptors in these Arctic soils, we will have to find gentle chemical treatments to probe this association, and test the hypothesis that Fe-humic associations can be tuned to differing Eh values.
12039892 Romanovsky, V. E. (University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK); Marchenko, S. S. and Kholodov, A. L. Detecting spatial variability in the ground temperature in a discontinuous permafrost region and attributing it to the physical and biological parameters [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C51B-03, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Recent observations indicate a warming of permafrost in many northern and mountain regions with a resulting degradation of ice-rich and carbon-rich permafrost. Permafrost temperature has increased by 1 to 2°C in northern Russia during the last 30 to 35 years. This observed increase is very similar to what has been observed in Alaska where the detailed characteristic of the warming varies between locations, but is typically from 0.5 to 2°C. In the last 30-years, warming in permafrost temperatures observed in the Russian North and Alaska has resulted in the thawing of permafrost in natural, undisturbed conditions in areas of the discontinuous permafrost zone. However, high spatial variability in ground surface conditions in the discontinuous permafrost zone produce a very diverse physical environment where mean annual ground temperatures (MAGT) may vary spatially by 5 to 6°C in the same climatic region. In this presentation, we will analyze ground temperature data collected during the last several years in an area north of Fairbanks in central Alaska. The observational sites were established along a profile across a small valley and encompass different topographic, hydrologic, and vegetation conditions and include sites where near-surface permafrost is present as well as the sites where permafrost is absent in the upper several meters. We found that the most pronounced difference in permafrost conditions along this profile is related to the site's elevation. Even if the difference in elevation between the ridge crest (338 m) and the valley bottom (175 m) is relatively small, the difference between mean annual air temperatures at these sites during the 2008-2010 period was about 3.4°C with higher temperature at the crest (-0.4°C) and lower at the valley bottom (-3.8°C). Well known winter temperature inversion effect is responsible for this difference. As a result, permafrost is generally absent at the higher elevations (MAGT at 1.2 m depth is +1.7°C at the crest site) and present in the lower elevations in this valley (MAGT at 1.2 m depth is -0.9°C at the valley bottom). However, other ecological conditions such as vegetation, soil moisture, and slope orientation are also play a very important role in forming the ground temperature regime. A complex interplay of these conditions will be illustrated in our presentation based on collected ground temperature data. Detection of permafrost presence or absence in the discontinuous permafrost zone using temperature measurements in shallow (0 to 1.5 m) boreholes will be also discussed.
12039890 Rowland, J. C. (Los Alamos National Laboratory, Earth & Environmental Sciences, Los Alamos, NM); Travis, B. J. and Wilson, C. J. The role of advective heat transport in talik development beneath lakes and ponds in discontinuous permafrost [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C51B-01, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
To date, models of talik (perennially unfrozen ground) development beneath lakes and ponds in permafrost terrain have focused on simulations with continuous, thick (>&eq;400 m), cold (<-6°C) permafrost using numerical solutions with solely conductive heat transfer. These models consistently predict only 10s of meters of talik development in centuries to millennia. In contrast, observations of lake loss in subarctic regions characterized by thin (20 to 60 m), warm, discontinuous permafrost (>&eq;-2°C) suggest that a through-going sub-lake talik may develop in a matter of decades. We modeled the development of a sub-lake talik under permafrost conditions similar to that observed in the southern Seward Peninsula region of Alaska using the Arctic Hydrology Model (ARCHY). ARCHY is a numerical solution that couples heat transport and groundwater flow including the effect of water phase changes on soil permeability and latent heat content. A comparison of model simulations, with and without near surface subpermafrost groundwater flow, indicate that stable permafrost thicknesses are 2 to 5 times greater in the absence of groundwater flow. Simulations examining the thermal influence of lakes on underlying permafrost suggest that through-going talik can develop in a matter of decades and that the incorporation of advective heat transport reduces the time to complete loss of ice beneath the lake by half, relative to heat transport by conduction alone. This work presents the first quantitative assessment of the rates of sub-lake permafrost loss in a system with near-surface groundwater flow. The results highlight the importance of coupled thermal and hydrologic processes on discontinuous permafrost dynamics.
12039888 Tape, K. D. (University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK) and Hallinger, Martin. Related changes in shrub growth, snow duration, and permafrost in response to post-1970s warming in Arctic Alaska [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C44B-04, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
In Arctic Alaska, vegetation constitutes a critical biological and physical layer sandwiched between permafrost and snow most of the year, and the interconnected nature of these three layers implies that a change in one layer will trigger changes in the others. The increase in air temperature since the 1970s has led to a 1-week earlier disappearance of snow, an expansion of deciduous shrubs, and a warming of the permafrost. I explored spatial and temporal relationships between shrub growth and ecosystem properties such as climate, permafrost, snow, and erosion. Alnus viridis ssp. fruticosa (Siberian alder) shrubs located along streams, floodplains, or other features with active disturbance regimes showed a positive correlation (P<0.05) between growth ring widths and March through July air temperature, linking the shrub expansion documented using repeat photography to warmer spring and summer temperatures. Climate-growth relationships were much weaker for alder in adjacent tussock tundra. Additionally, tussock tundra sites had different vegetation composition, shallower thaw, lower mean annual ground temperature, lower mean growing season temperature, higher soil moisture, more carbon in mineral soil, and higher C:N values in shrub leaves than nearby non-tussock alder. Growth rings and site characteristics imply that soil properties predispose alder shrubs growing in non-tussock tundra with deeper active layer to respond rapidly to the warmer summers and earlier snowmelt since the 1970s. In contrast, the thick organic layer in areas of tussock tundra better insulates the permafrost from changes in air temperature. Riparian areas and other areas of elevated disturbance regime have therefore responded preferentially to air temperature increases since the 1970s.
12039936 Wollschlaeger, Ute (UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany); Gerhards, Holger; Westermann, Sebastian; Pan, Xicai; Boike, J.; Schiwek, Philip; Yu, Q. and Roth, Kurt. Exploring active layer thaw depth and water content dynamics with multi-channel GPR [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract NS51A-1736, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
In permafrost landscapes, the active layer is the highly dynamic uppermost section of the ground where many important hydrological, biological and geomorphological processes take place. Active layer hydrological processes are controlled by many different factors like thaw depth, soil textural properties, vegetation, and snow cover. These may lead to complex runoff patterns that are difficult to estimate from point measurements in boreholes. New multi-channel GPR systems provide the opportunity to non-invasively estimate reflector depth and average volumetric water content of distinct soil layers over distances ranging from some ten meters up to a few kilometers. Due to the abrupt change in dielectric permittivity between frozen and unfrozen ground, multi-channel GPR is a valuable technique for mapping the depth of the frost table along with the volumetric water content of the active layer without the need of laborious drillings or frost probe measurements. Knowing both values, the total amount of water stored in the active layer can be determined which may be used as an estimate of its latent heat content. Time series of measurements allow spatial monitoring of the progression of the thawing front. Multi-channel GPR thus offers new opportunities for monitoring active layer hydrological processes. This presentation will provide a brief introduction of the multi-channel GPR evaluation technique and will present different applications from several permafrost sites.
12047585 Wong, Gifford J. (Dartmouth College, Department of Earth Sciences, Hanover, NH); Overly, Thomas B.; Courville, Zoe R.; Hawley, Robert L.; Lutz, Eric R. and Osterberg, Erich C. Thule to Summit; using the physical and chemical properties of shallow firn to describe glacier facies, accumulation, and 55 years of change [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C33A-0625, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Between 1952 and 1955, Carl Benson and the US Army Snow, Ice and Permafrost Research Establishment undertook a series of traverses of the Greenland Ice Sheet (GIS). Employing a number of physical measurements, Benson (1962) characterized the GIS via mapping of the spatial distribution of annual net accumulation and classifying the diagenetic glacier facies. Recent advances in remote sensing techniques now provide a number of ways to assess the state of the GIS, but these techniques still require some component of in situ verification. In the springs of 2010 and 2011, we undertook a 1200 km traverse along a nearly-identical route on the GIS from Thule Air Base to Summit Station. Along the traverse route, we characterized the physical stratigraphy of the near-surface (0-10 m depth) snow using an array of observations such as density, grain size, hardness, optical stratigraphy and temperature. We collected a total of 30 snow pits and 14 shallow firn cores over the two field seasons. These measurements allow us to make comparisons with Benson's results, identifying changes in glacier facies and accumulation patterns over the past 55 years. In addition to physical stratigraphy, we measured snowpit chemical stratigraphy (major ions, trace elements and stable water isotopes) at 5-10 cm resolution. These measurements allow us to date horizons seen in the physical stratigraphic record, and to explore questions about the spatial variability of species deposition. Here, we present an initial analysis of these snowpits, shallow cores, and BOS logs, co-located with near infrared imagery, ground-penetrating radar and kinematic GPS data (see Lutz et al. and Overly et al., both this session), which will be useful in quantifying spatial and temporal changes in glacier facies, accumulation rates, and geochemical cycling on the GIS.
12047497 Zhang, Yu (Natural Resources Canada, Canada Centre for Remote Sensing, Ottawa, ON, Canada). Long-term projections of permafrost conditions at landscape scale for a region in Hudson Bay Lowland in Canada [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C21D-05, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.
Although studies agree that climate warming will cause permafrost thaw, projected changes in permafrost conditions vary widely. Most permafrost projections used very coarse spatial resolution. This study projected changes of permafrost at a spatial resolution of 30 m by 30 m for a region in northwest Hudson Bay lowland in Canada. A process-based model was used for the projections from 2010 to 2200 based on two climate change scenarios generated by global climate models. This spatially detailed, long-term modeling shows that permafrost degradation is heterogeneous, and permafrost will become increasingly discontinuous with time. By the end of the 22nd century in this region, 36.6%-80.0% of the land would be permafrost free, and 17.8%-40.2% of the land would contain permafrost with taliks, and 2.2%-23.3% of the land would contain permafrost without taliks. Because of the formation of taliks, maximum summer thaw depth would increase significantly and near-surface permafrost would disappear in many areas while permafrost in depth could persist for decades. Thus, the spatial distributions of near-surface permafrost and permafrost in depth could be very different. For individual sites, the process of permafrost degradation generally follows four stages: (1) gradual deepening of active-layer, (2) increased deepening of active-layer before developing taliks, (3) taliks formed frequently with large variations in permafrost table and active-layer thickness, and (4) taliks became deep enough that permafrost table seldom connected with the top seasonal thawing/freezing layer. The duration and thickness of the thawing/freezing layers near the land surface could fluctuate widely from year to year during the stages 2 and 3. Although most of the warming in atmospheric climate occurred in the 21st century, the disappearance of permafrost in the 22nd century was similar or even larger than that of the 21st century. This study also demonstrates that climate change scenarios, depths considered for permafrost, and spatial scales and associated ground conditions used for modeling could significantly affect permafrost projections.
12045329 Bierman, P. (University of Vermont, Department of Geology, Burlington, VT); Corbett, Lee B.; Finkel, Robert; Graly, Joseph A.; Hughes, John; Lini, Andrea; Neumann, Thomas A. and Rood, Dylan. Ancient, slowly-eroding soil preserved beneath the summit of the Greenland ice sheet [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 217, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
Cores that extend to the bed of ice sheets contain sediment-rich basal ice zones. In order to constrain better the source and character of sediment in the lower meters of the 3053-m long GISP2 ice core (the "silty ice zone"), we measured the concentration of meteoric 10Be, organic carbon, and nitrogen in sediment separated from 17 core samples. The samples represent a total of 3 m of ice including an 11 cm section directly above the bed. Meteoric 10Be is a cosmogenic isotope formed in the atmosphere and delivered to Earth's surface by precipitation and dry fall. It is an excellent tracer of sediment exposed to pedogenic processes; high concentrations of meteoric 10Be are indicative of soil and sediment originating within several meters of Earth's surface. Organic carbon and nitrogen are also markers of soil formation. Silt in the lowermost 6.5 m of the GISP2 ice core has high concentrations of meteoric 10Be (0.6 to 3.8 ´ 108 atoms/g), significant percentages of organic carbon (0.3 to 1.7%), and an average C/N ratio of ~10, all consistent with derivation from a well-developed, cold-region soil. The highest concentrations of meteoric 10Be and TOC were measured in the bottom-most ice sample. The 10Be concentration is consistent with a soil inventory > 1010 atoms/cm2 implying a soil exposure time > 105 years before the soil was covered by ice. As Pleistocene interglacial periods were all short (<104 year) and few, if any, exposed the bed under GISP2, meteoric 10Be data imply the preservation of soil formed during pre-Quaternary interglacial exposure. Concentrations of meteoric 10Be and total organic carbon co-vary and decrease with distance from the bed, a trend consistent with other data suggesting that the underlying soil is mixed, by ice deformation, with rock flour derived from bedrock erosion elsewhere. The GISP2 core location has likely been ice covered, with the possible exception of a short (4-7 ky) exposure at MIS 11 (Nishiizumi et al., 2006), since 2.5 Mya (Larsen et al., 1994), providing a minimum limiting age for the paleosol underlying Summit, Greenland. The continued existence of this ancient soil indicates extremely low rates of sub-ice erosion at GISP2. Survival of the soil for several million years under the Greenland Ice Sheet is consistent with the ice at Summit having been frozen to the bed for most, if not all, of the Quaternary.
12045363 Famiglietti, James (University of California, Irvine, Center for Hydrologic Modeling, Irvine, CA); Rodell, Matthew; Swenson, Sean; Chambers, Don; Lo, Min-Hui; Reager, J. T.; Voss, Katalyn; Rozier de Linage, Caroline and Ho, Stephanie. Groundwater depletion as a global phenomenon [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 222-223, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
Over 2 billion people rely on groundwater as their primary source of water for domestic, industrial and agricultural needs. Ironically however, monitoring groundwater use remains challenging, even in the developed world. In the developing world, it is often non-existent. Over the last decade, advances in satellite remote sensing are providing new means for monitoring groundwater storage changes in the world's large aquifer systems. Specifically, NASA's Gravity Recovery and Climate Experiment (GRACE) mission provides monthly data on terrestrial water storage changes (i.e. for all of the snow, surface water, soil moisture and groundwater) in regions that of at least 200,000 square kilometers. Combining GRACE data with independent observations of snow, surface water and soil moisture has proven to be an effective means of characterizing groundwater storage changes. In this presentation, the GRACE-based methodology will be reviewed, and groundwater storage changes in the world's major aquifer systems will be presented. Current rates of groundwater depletion will be discussed in the context of a sustainable water future.
12045193 Johnson, Mark D. (University of Gothenburg, Earth Sciences Institute, Goteborg, Sweden); Mickelson, David M.; Clayton, Lee; Attig, John W.; Ham, Nelson R. and Syverson, Kent M. Southern Laurentide ice sheet dead-ice topography; the "Wisconsin View" and new opportunities [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 175, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
Much of the Late Glacial Maximum margin of the Laurentide Ice Sheet in Wisconsin is marked by extensive tracts of dead-ice topography. These areas are characterized by numerous irregular hummocks and swales occurring together in a band parallel to the former ice-margin position and extending several kilometers up ice. Ice-walled-lake plains are a common feature in these landscapes. We have analyzed the geomorphology and internal composition of these hummocks while making county maps throughout the state. This dead-ice topography is produced by gradual melting of stagnant ice that had thick supraglacial debris. The supraglacial debris was derived from the ice bed by freezing-on, thrusting, and stacking near the margin. There is abundant evidence that the ice lobes that left behind hummocks topography advanced into permafrosted terrain and, in many cases, likely at fast-flow rates (surging or streaming). These two factors, along with up-gradient bed slopes in places, accentuated the marginal thrusting processes and increased the amount of supraglacial debris. In places, preferred orientation of hummocks likely reflects structures in the parent ice. The presence of tunnel channels cutting through hummocky terrains is also an expression of ice with a frozen toe and rapid ice flow. Following stagnation, the presence of permafrost controlled the rate and timing of dead-ice melting. The chaotic pattern and meso-scale of "classical hummocky topography" has precluded sophisticated morphometric analysis, but the increasing availability of LIDAR elevation data will likely yield greater insight into the geomorphology and genesis of dead-ice topography.
12045333 Mickelson, David M. (University of Wisconsin-Madison, Department of Geosciences, Madison, WI). Quaternary geology and geomorphology division distinguished career award; changes in glacial landforms and subglacial conditions in the ice-marginal zone of the Laurentide ice sheet from southern Wisconsin to Minnesota [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 217-218, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
About 30,000 cal BP ice advanced into Wisconsin over permafrost that was as much as 100 m thick. It is likely that relatively little work was done by the frozen-bed glacier until subglacial permafrost beneath thick ice slowly melted and more rapid sliding began to take place behind a frozen toe. This frozen bed zone must have widened toward the north. Tunnel channels carried large volumes of water to the ice margin while there was still at least a 15 km-wide frozen bed around the margin in southern Wisconsin. Tunnel channels are absent in central Illinois, abundant along the Green Bay Lobe margin where water beneath the ice flowed up the regional slope, and more widely spaced, but longer along the margins of ice out of the Lake Superior Basin. Behind that frozen zone the bed was going through a transition from frozen to wet bed, and drumlins were forming. No flat till plain was left behind as it was farther south in Illinois. Although permafrost remained in the south until about 15,000 cal BP and later in the north, perhaps by about 22,000 cal BP climate began to warm sufficiently to allow sliding and basal water accumulation out to the outermost margin. Striations and grooves, indicating sliding, as well as small eskers are present within a few km of the outermost advance, indicating that ice warmed to the base before significant retreat. Internal relief in the end moraine increases from about 10 m in southern Wisconsin, to nearly 100 m in the north, reflecting an increasing thickness of supraglacial sediment in the north. High relief ice-walled-lake plains are common in the north, but nearly absent in the end moraines of southern Wisconsin. In northern Wisconsin, ice advances interpreted to be surges cross-cut deposits of somewhat earlier advances. The Green Bay Lobe readvances, however, seem to have followed the same path until very late in the deglaciation process. The diverse landscapes resulting from distinctly different subglacial conditions are well illustrated along the 1200-mile Ice Age National Scenic Trail and in the Ice Age National Scientific Reserve.
12045318 Molnia, Bruce F. (U. S. Geological Survey, Reston, VA); Angeli, Kim M.; Noyles, Christopher C.; Bratton, David A. and Keeler, Ronald H. Meltwater origin for the 2005 Mount Steller, Alaska landslide [abstr.]: in Geological Society of America, 2011 annual meeting, Abstracts with Programs - Geological Society of America, 43(5), p. 215, October 2011. Meeting: Geological Society of America, 2011 annual meeting, Oct. 9-12, 2011, Minneapolis, MN.
On September 14, 2005, a massive landslide originated from just below the south-facing summit of 3,236-m-high Mount Steller, Alaska, removing a near-summit hanging glacier and a substantial amount of rock and snow. Much of the displaced slide mass landed on the surface of an unnamed tributary of Bering Glacier, nearly 2,500 m below. The slide runout extended more than 8 km down the glacier from the point of impact. Much of the summit area surface from which the slide occurred had a slope >50°. The volume of the slide was estimated by the Alaska Volcano Observatory to be approximately 50 ´ 106 m3. Unlike most large Alaskan glacier-related landslides, this one was not triggered by an earthquake. However, the energy that the slide released was intense enough to generate a seismic signal recorded around the world with magnitudes of 3.8 to greater than 5. Several just publicly released, one-meter resolution electro-optical images collected by U.S. National Systems in October 2005, provide new evidence pertaining to processes active at the summit at the time of the slide. Previously, Huggel and others (2008) proposed a warming of bedrock permafrost temperatures with possible destabilization processes resulting from water infiltration and refreezing, effective through a system of cracks and hydrostatic pressure variations in cracks and micro-fractures, as the cause of the slide. Molnia and others (2006) described glaciological evidence that suggested that a large volume of water had recently flowed on Mt Steller's east ridge and that englacial meltwater had a role in triggering the landslide. The newly released National Systems imagery shows evidence of liquid water flowing out of a moulin or englacial stream channel from the truncated glacier ice face on the east wall of the landslide scarp and fractured ice that corresponds to another part of the englacial channel on the west flank of the scarp. The presence of these unusual glacial-hydrologic features at an elevation above 3,000 m, suggests an unusually large melting of summit snow and ice, a process confirmed by sequential imagery. This is supported by the newly released imagery. The presence of a large volume of meltwater close to Mt. Steller's summit raises questions about regional climate change and its role in the future generation of landslides at higher elevations and latitudes.
12040966 Amundson, R. (University of California, Berkeley, Environmental Science and Policy Management, Berkeley, CA); Barnes, J. D.; Ewing, S.; Heimsath, A. and Chong, G. The stable isotope composition of chlorine in hyperarid soils [abstr.]: in Goldschmidt 2011 abstract volume, Mineralogical Magazine, 75(3), p. 432, 1 ref., 2011. Meeting: Goldschmidt2011, Aug. 8-14, 2011, Prague, Czech Republic.
Halite (NaCl) is a water soluble mineral found in soils of the driest regions of Earth, and only modest attention has been given to the hydrological processes that distribute this salt vertically in soil profiles. The recent application of stable Cl isotope analyses to soils (Bao et al., 2008) set in motion the opportunity to use Cl isotopes to examine these processes. Here, we compare previously published depth profiles of Cl and Cl isotopes in Antarctica to new data on soils from the Atacama Desert in Chile. We first show, using previously published S and O isotope data for sulfates in both deserts, that downward migration of water and sulfate is the primary mechanism responsible for the depth profiles of these salts, and the S and O isotopes within them. In contrast, we found quite different Cl and Cl isotope profiles between the two deserts. For Antarctic soils with an ice layer near the soil surface, the Cl concentrations increase with decreasing soil depth, while the ratio of 37Cl/35Cl increases. Based on previous field observations by others, we found that thermally driven upward movement of brine during the winter, described by an advection/diffusion model, at least qualitatively mimics the observed profiles. In contrast, in the Atacama Desert where rare but relatively large rains drive Cl downward through the profiles, Cl concentrations increased with depth while 37Cl/35Cl ratios declined. The depth trends in Cl isotopes were more closely explained by a Rayleigh-like model of downward fluid flow. The isotope profiles, and our modeling, reveal the similarities and differences between these two very arid regions on Earth, and provide additional tools to interpret the direction of fluid flow from Cl profiles on Mars. Bao H., Barnes J.D., Sharp Z.D., and Marchant D.R. (2008) Two chloride sources in soils of the McMurdo Dry Valleys, Antarctica. Journal of Geophysical Research 113(D03301)
12041024 Astrom, Mats E. (Kalmar University, School of Natural Sciences, Kalmar, Sweden); Boman, A. and Frojdo, S. Fast iron sulfide oxidation in a region of land uplift and artificial drainage [abstr.]: in Goldschmidt 2011 abstract volume, Mineralogical Magazine, 75(3), p. 460, 4 ref., 2011. Meeting: Goldschmidt2011, Aug. 14-19, 2011, Prague, Czech Republic.
Postglacial isostatic uplift (currently up to 1 meter per 100 years) has brought large areas of land above the sea level in low-lying coastal areas of northern Europe. These exposed land masses are to a significant part covered by thick marine sediments, characterised by unusually high concentrations of fine-grained metastable iron sulfides (up to 1%) in an aluminosilicate clay-silt matrix [1, 2]. When drained for agricultural purposes, these sediments rapidly develop into acidic (acid sulfate) soils and release an abundance of metals (Mn, Al, Ni, Zn, Co, Be, Ln) into drains, despite the cold climate with frozen ground and a thick snow cover for about half of the year [3, 4]. We suggest that microbially mediated oxidation of the metastable iron sulfides initiate the soil ripening process, leading to a fast decrease in pH which favours further pyrite oxidation and silicate weathering. The farmers are worried and the environment - including surface waters and down-stream sediments - is acidified and contaminated. There is thus an urgent need to increase the understanding of this on-going landscape-wide acidification process, in which the preservation and oxidation and toxic-metal content of the metastable iron sulfides is a key parameter.
12039114 Cadieux, S. B. (University of Tennessee, Department of Earth and Planetary Sciences, Knoxville, TN) and Kah, L. C. Intracrater layered deposits in Arabia Terra, Mars indicate potential wet, cold, conditions in late Noachian-early Hesparian: in Lunar and planetary science conference XLII; papers presented to the Forty-second lunar and planetary science conference, Abstracts of Papers Submitted to the Lunar and Planetary Science Conference, 42, Abstract no. 1265, illus., 8 ref., 2011. Meeting: Forty-second lunar and planetary science conference, March 7-11, 2011, Woodlands, TX. Accessed on Oct. 7, 2011.
12039065 McClanahan, Timothy P. (NASA, Goddard Space Flight Center, Astrochemistry Laboratory, Greenbelt, MD); Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Starr, R. D.; Evans, L. G.; Droege, G.; Sanin, A. B.; Garvin, James B. and Trombka, J. Insolation effects on the Moon; high topographic slope observations from the LRO LEND and LOLA instruments: in Lunar and planetary science conference XLII; papers presented to the Forty-second lunar and planetary science conference, Abstracts of Papers Submitted to the Lunar and Planetary Science Conference, 42, Paper 1970, illus., 8 ref., 2011. Meeting: Forty-second lunar and planetary science conference, March 7-11, 2011, Woodlands, TX. Accessed on Dec. 15, 2011.
12038710 Froberg, Mats (Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden); Bryant, Charlotte and Kleja, Dan Berggren. Turnover of mineral-free and mineral-associated organic matter in a soil warming experiment in northern Sweden [abstr.]: in Abstracts of the 20th annual V. M. Goldschmidt conference, Geochimica et Cosmochimica Acta, 74(12, Suppl. 1), p. A307, 2010. Meeting: 20th annual V. M. Goldschmidt conference, June 13-18, 2010, Knoxville, TN.
12044563 Jackson, W. Andrew (Texas Tech University, Lubbock, TX); Rao, Balaji; Rajagopolan, Srinath; Böhlke, J. K.; Hatzinger, Paul B.; Sturchio, Neil C.; Gu, Baohua; Betancourt, Julio; Andraski, Brian; Stonestrom, David; Orris, Greta J. and Eckardt, Frank. Relation between NO3- and ClO4- occurrence in the environment [abstr.]: in Abstracts of the 20th annual V. M. Goldschmidt conference, Geochimica et Cosmochimica Acta, 74(12, Suppl. 1), p. A451, 2010. Meeting: 20th annual V. M. Goldschmidt conference, June 13-18, 2010, Knoxville, TN.
12044435 Pancost, R. D. (University of Bristol, School of Chemistry, Bristol, United Kingdom); Aquilina, A.; Talbot, H. M.; Lim, K.; Evershed, R. P.; Bull, I. D.; Gill, F.; Weijers, J.; Collinson, M. E. and Taylor, K. Biomarkers for methane cycling; from marine to terrestrial settings [abstr.]: in Abstracts of the 20th annual V. M. Goldschmidt conference, Geochimica et Cosmochimica Acta, 74(12, Suppl. 1), p. A787, 2010. Meeting: 20th annual V. M. Goldschmidt conference, June 13-18, 2010, Knoxville, TN.
12044263 Sturchio, Neil C. (University of Illinois at Chicago, Chicago, IL); Beloso, A. D., Jr.; Böhlke, J. K.; Caffee, Marc W.; Gu, B.; Hatzinger, P. D.; Heraty, L. J. and Jackson, W. Andrew. Isotopic tracing of the origin and transport of perchlorate [abstr.]: in Abstracts of the 20th annual V. M. Goldschmidt conference, Geochimica et Cosmochimica Acta, 74(12, Suppl. 1), p. A1001, 4 ref., 2010. Meeting: 20th annual V. M. Goldschmidt conference, June 13-18, 2010, Knoxville, TN.
12044338 Tfaily, M. (Florida State University, Tallahassee, FL); D'Andrilli, J.; Corbett, E.; Chanton, J. P. and Cooper, William T. Molecular characterization of dissolved organic matter (DOM) in northern peatlands; identifying the chemical signatures of climate change [abstr.]: in Abstracts of the 20th annual V. M. Goldschmidt conference, Geochimica et Cosmochimica Acta, 74(12, Suppl. 1), p. A1038, 1 ref., 2010. Meeting: 20th annual V. M. Goldschmidt conference, June 13-18, 2010, Knoxville, TN.
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12043550 Abraham, Jared (U. S. Geological Survey). A promising tool for subsurface permafrost mapping; an application of airborne geophysics from the Yukon River basin, Alaska: Fact Sheet - U. S. Geological Survey, Rep. No. FS 2011-3133, 4 p., illus. incl. sects., sketch maps, 4 ref., November 2011. Accessed on April 17, 2012.
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