|
12014223 Baker, Andy (University of New South Wales, Connected Water Initiative Research Centre, Manly Vale, N.S.W., Australia); Wilson, Rob; Fairchild, Ian J.; Franke, Joerg; Spotl, Christoph; Mattey, Dave; Trouet, Valerie and Fuller, Lisa. High-resolution d18O and d13C records from an annually laminated Scottish stalagmite and relationship with last millennium climate: in Rapid climate change; lessons from the recent geological past (Holmes, Jonathan A., editor; et al.), Global and Planetary Change, 79(3-4), p. 303-311, illus. incl. 1 table, sketch map, 52 ref., December 2011.
High-resolution (annual to decadal) stable isotope records of oxygen and carbon are analysed from an annually laminated stalagmite from NW Scotland. The sample, which was deposited for ~1000 yrs until 1996 AD, has previously provided annual resolution climate reconstructions of local rainfall and regional winter North Atlantic Oscillation (wNAO) from variations in annual growth rate. For our stalagmite, for which modern cave monitoring demonstrates that equilibrium deposition is highly likely for d18O but not for d13C, stalagmite d13C originally derives from soil CO2 produced predominantly by microbial respiration, modified by degassing-related kinetic fractionation, and d18O from the composition of infiltrating water during periods of infiltrating water. Both the presence of fluorescent laminae and modern drip-water monitoring demonstrate a drip hydrology that comprises both event and storage components. Over the instrumental period, no correlations between stalagmite or rainfall d18O and precipitation amount or temperature are observed, but correlations are observed between rainfall d18O and 500 mb height at regional IAEA monitoring stations. However, no correlations are observed between stalagmite d18O and instrumental and reconstructed atmospheric circulation, preventing a simple palaeoclimate interpretation of the stalagmite d18O proxy. Stalagmite d13C has a stronger temporal autocorrelation than d18O, indicative of soil mixing of respired CO2 and significant variability between drips and at different times; correlations with instrumental climate data are therefore not possible. The relative timing of changes in growth rate, d18O and d13C are discussed, and interpretations compared with other regional climate records. We conclude that, over the last millennium at this mid-latitude cave site, neither d18O nor d13C cannot be interpreted as a simple paleoclimate proxy.
DOI: 10.1016/j.gloplacha.2010.12.007
12020852 Zhang Jianguo (Nantong University, School of Geography, Nantong, China); Wang Yingli; Ji Yusong and Yan Dezhi. Melting and shrinkage of cryosphere in Tibet and its impact on the ecological environment: Journal of Arid Land = Ganhanqu Kexue, 3(4), p. 292-299, 2 tables, 23 ref., December 2011.
Global warming is having a profound impact on global ecological systems, and has inevitably induced changes in the cryosphere, one of the five layers of the earth. Major changes include the shrinking and reduction in the area and volume of both the mountain glaciers and the ice caps covering the North and South poles, and the melting of permafrost and thickening of the active frost layer. Swift changes in the cryosphere have inevitably induced ecological and environmental changes in its zone. While some of these changes are beneficial to mankind, such as an increase in water circulation, short term increases in water volumes and the enlargement of the cultivatable area, others are extremely hazardous, like the flooding of lowlands caused by an increased sea level elevation, debris flow caused by glaciers, glacier lake bursts, undermined building safety caused by permafrost melting, the deterioration of alpine cold meadows, and the surface aridization and desertification of land. Tibet, having a major part of the cryosphere in China, is home to the most widely spread glaciers and permafrost, which play a vital role in regulating water resources, climate, environment and the ecological safety in China and Asia. However, due to global warming, the glaciers and permafrost in Tibet have recently changed dramatically, exhibiting shrinkage and melting, which threatens long-term water resources, and the ecological and environmental safety of China. Based on existing research, this paper discusses the relationship between global warming and the melting and shrinkage of the cryosphere. The results show that the cryosphere's melting and shrinkage in Tibet are the direct result of global warming. The melting of glaciers has led to a series of disasters, such as changes in river runoff, the heightened frequency of debris flows induced by glaciers and the outbursts of glacier lakes. The melting of the permafrost also resulted in a series of ecological and environmental problems in Tibet, such as the degradation and population succession of the alpine grassland and meadows, the aridization of the land surface, and the occurrence of freeze-thaw erosion.
DOI: 10.3724/SP.J.1227.2011.00292
12016216 Edwards, Kevin J. (University of Aberdeen, Department of Geography and Environment, Aberdeen, United Kingdom); Schofield, J. Edward; Kirby, Jason R. and Cook, Gordon T. Problematic but promising ponds? Palaeoenvironmental evidence from the Norse Eastern Settlement of Greenland: JQS. Journal of Quaternary Science, 26(8), p. 854-865, illus. incl. 3 tables, strat. col., sketch maps, 76 ref., November 2011.
Pollen- and related proxy-based studies of human-environment interactions during the Norse and later periods within Greenland have primarily involved the investigation of peat, lake and soil deposits, all of which have taphonomic and sampling problems. Many small ponds exist, but they seem to have been relatively ignored in investigations of paleoecologically based environmental history. To evaluate their usefulness for studies of ecologically related cultural history, especially where sites are in intimate association with the archaeology, a pond in the Norse Eastern Settlement has been examined to investigate three principal questions: (i) Does such a site contain a useful record of environmental history? (ii) Does it offer a record of sufficient resolution and sensitivity for the study of anthropogenic landscape impacts? (iii) Are there any apparent drawbacks to these sequences? Using data obtained from palynological, diatom, sedimentological and radiocarbon analyses, it is concluded that environmental data for each proxy--aside from 14C dating--are clearly capable of being explained in a reasonably straightforward and compatible manner and fulfill the hopes for the sampling medium. Abstract Copyright (2010), John Wiley & Sons, Ltd.
DOI: 10.1002/jqs.1518
12014131 Helama, Samuli (University of Lapland, Arctic Centre, Rovaniemi, Finland); Tuomenvirta, Heikki and Venalainen, Ari. Boreal and subarctic soils under climatic change: Global and Planetary Change, 79(1-2), p. 37-47, illus. incl. 3 tables, sketch map, 63 ref., October /1, 2011.
Changing climate and warming atmosphere are supposed to result in changing thermal regimes of soils with a spectrum of impacts for terrestrial heat-flow, ecological and biochemical processes including vegetation and carbon dynamics. Here, six sites within an area of significant recent climatic warming, between 70° and 60°N, provided data of air and soil temperatures and snow depth to analyze the spatiotemporal air-soil temperature associations during the period 1971-2010. The air temperatures exhibited significant trends of warming across the boreal and subarctic regions. The records of snow depth showed trends of snowpack thinning and the soil temperature trends of warming especially in the southern and middle boreal sites. The boreal and subarctic sites showed predominant influence of air temperature variability on soil thermal conditions, with modulating effects of thermoinsulation caused by the snowpack. The yearly variations in soil temperatures correlated highly with those of air temperatures and the positive trend in soil temperatures was sufficiently explained by air temperature warming in the majority of the sites. The results thus propose that the climate change could be directly causing alterations in the soil thermal regime and the warming of soils, with generally expected continuation, driven by air temperature warming as projected by model simulations. The thermoinsulation effects during the winter were strongest in the northern boreal zone where the temperature difference between the air and soil temperatures was largest and the correlations between snow depth and soil temperatures were highest during the winter months. Likewise, the rate of air temperature warming appeared strongest in our northern boreal site where the soil temperature warming showed non-significant trend only. The evidence for temporal air-soil temperature decouplings and spatial disparity between the air and soil temperature data both expressed the importance of studying the soil temperature change in situ. In the same context, the potential for temperature induced soil organic carbon decomposition coincided spatially with the highest quantities of available carbon as indicated for our boreal and subarctic soils.
DOI: 10.1016/j.gloplacha.2011.08.001
12014133 Swanger, Kate M. (Boston University, Department of Earth Sciences, Boston, MA); Marchant, David R.; Schaefer, Joerg M.; Winckler, Gisela and Head, James W. Elevated East Antarctic outlet glaciers during warmer-than-present climates in southern Victoria Land: Global and Planetary Change, 79(1-2), p. 61-72, illus. incl. 3 tables, sketch maps, 51 ref., October /1, 2011.
We document Plio-Pleistocene changes in the level of Taylor Glacier, an outlet glacier in southern Victoria Land that drains Taylor Dome on the periphery of the East Antarctic Ice Sheet (EAIS). Chronologic control comes from 3He cosmogenic-nuclide analyses of 27 boulders sampled from drifts and moraines in Kennar Valley, a small hanging valley that opens onto a peripheral lobe of Taylor Glacier in the Quartermain Mountains. Assuming a constant boulder-erosion rate of 10 cm Myr-1, our preferred age model spans the last 3.1 Myr and calls for stepped ice recession from a local highstand ~200 m above the present base of Taylor Glacier at the mouth of Kennar Valley. The texture and sedimentology of all mapped moraines and drifts indicate deposition from cold-based ice, analogous with the modern Taylor Glacier at the mouth of Kennar Valley. The Kennar Valley glacial record shows an uncharacteristic relationship with average global temperatures, exhibiting higher-than-present ice levels during globally warm periods, including the Pliocene climatic optimum (~3.1 Ma) and Marine Oxygen Isotope Stage (MIS) 31 (~1.07 Ma). The Kennar Valley record also suggests that the rate of ice-surface lowering accelerated after the mid-Pleistocene transition at ~0.9 Ma. Correlation of our moraine record with published reports for fluctuations of Taylor Glacier elsewhere in the Quartermain Mountains, and with a dated moraine record from Ferrar Glacier (a second outlet for Taylor Dome), reveals similar ice-surface changes, highlighting minor, but widespread ice recession in southern Victoria Land since the mid- to late-Pliocene. Our record for minimal variability in the East Antarctic Ice Sheet contrasts with recent data from nearby marine cores that call for dynamic fluctuations in the volume of grounded ice in the Ross Embayment, and significant reduction of the West Antarctic Ice Sheet (WAIS) during warmer-than-present intervals. Taken together, these records from the Ross Embayment call for considerable variation in the response of marine-based West Antarctic ice and terrestrial East Antarctic outlet glaciers during Plio-Pleistocene time.
DOI: 10.1016/j.gloplacha.2011.07.012
12017522 Fontaine, Pier-Olivier (École Polytechnique de Monteréal, Department of Civil, Geological and Mining Engineering, Montreal, QC, Canada); Marcotte, Denis; Pasquier, Philippe and Thibodeau, Denis. Modeling of horizontal geoexchange systems for building heating and permafrost stabilization: Geothermics, 40(3), p. 211-220, illus. incl. 2 tables, 12 ref., September 2011.
We present a new analytical model based on the finite line source that extends the steady state results for parallel horizontal pipes to the transient case and for any desired horizontal pipe layout. The analytical model is validated, when there is no freezing/thawing, by a 3D finite element numerical model. When the phase change is accounted for in the numerical model, the analytical model still provides good approximation to the ground temperature during the heating season and the heat extracted by the ground heat exchanger. However, summer ground temperature and thaw depth are overestimated by the analytical model. A case study for a typical building in Kuujjuaq (northern Canada) area is analyzed. The ground heat exchanger layout follows a spiral pattern characterized by three parameters: length L, depth D, and spacing S. The influence of each parameter on the amount of heat extracted from the ground and on the ground temperature at a control point is assessed. The results show that increasing depth D favors keeping the ground frozen at this depth and increases the amount of heat that may be extracted. Conversely, increasing S and/or L is beneficial for the amount of heat extracted, but it enhances the risk of thawing around the pipes. The model and case study provides useful ground heat exchanger design guidelines in cold regions for the double purpose of ground freezing and heat extraction.
DOI: 10.1016/j.geothermics.2011.07.002
12015873 Lechler, Alex R. (University of Michigan, Department of Geological Sciences, Ann Arbor, MI) and Niemi, Nathan A. The influence of snow sublimation on the isotopic composition of spring and surface waters in the southwestern United States; implications for stable isotope-based paleoaltimetry and hydrologic studies: Geological Society of America Bulletin, 124(3-4), p. 318-334, illus. incl. 1 table, sketch maps, 92 ref., September 30, 2011.
The preservation of the d18O and dD composition of rain and snow, and resulting isotope-elevation gradients, in terrestrial waters derived from precipitation, such as streams, lakes, snowmelt, and soil waters, is often an inherent assumption in paleoclimate, hydrologic, and paleoelevation studies utilizing paleo-meteoric water proxy records. Modern spring and surface water samples from the southwestern United States along a latitudinal transect at ~36°N from the southern Sierra Nevada, California, to the central Basin and Range reveal that spring and surface waters collected from the orographic slope on the western side of the Sierra Nevada preserve isotopic compositions and d18O-elevation gradients (-2 to -3 per mil/km) that are consistent with published regional precipitation records and that are similar to values expected based on simple Rayleigh distillation processes. In contrast, high-elevation (>&eq;2000 m) spring waters from the Panamint and Spring Mountains in the orographic rain shadow on the eastern side of the Sierra Nevada exhibit d18O values (~-14 per mil to -13 per mil relative to Vienna standard mean ocean water [VSMOW]) that are significantly higher than those of the winter season precipitation (-22 per mil to -15 per mil) from which the terrestrial waters are derived, yielding spring water d18O-elevation gradients (~-0.8 per mil/km) that are 2-3 times lower than those derived from regional precipitation values (~-2.0 per mil/km) and those predicted by Rayleigh distillation models. The observed discrepancy between precipitation and terrestrial water isotopic compositions and the reduced spring water d18O-elevation gradients in the Panamint and Spring Mountains suggest that elevation-dependent modification of the isotopic composition of precipitation following deposition plays a key role in the isotope hydrology of meteoric water systems in the continental interior southwestern United States. We demonstrate that altitude-dependent sublimation of the winter snowpack is a viable mechanism for the observed isotopic enrichment and reduced d18O-elevation gradients of Basin and Range spring waters. This finding suggests that atmospheric processes alone may be insufficient to explain globally observed variations in d18O-elevation gradients, and that the geologic record of the d18O composition of paleo-meteoric waters may not accurately reflect the d18O compositions of paleoprecipitation, particularly in arid environments dominated by winter precipitation in the form of snow. If unaccounted for, sublimation effects can lead to significant underestimates of both paleoelevation (on the order of 2-3 km) as well as the contribution of winter season precipitation to annual groundwater recharge. As a result, consideration of potential sublimation influence on paleo-meteoric water systems, particularly as can be constrained by paleoclimate reconstructions, is necessary in order to accurately derive quantitative estimates of paleoelevation and seasonal groundwater recharge.
DOI: 10.1130/B30467.1
12013890 Deepagoda, T. K. K. Chamindu (Aalborg University, Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg, Denmark); Moldrup, Per; Schjonning, Per; Kawamoto, Ken; Komatsu, Toshiko and de Jonge, Lis Wollesen. Generalized density-corrected model for gas diffusivity in variably saturated soils: Soil Science Society of America Journal, 75(4), p. 1315-1329, illus. incl. 3 tables, 56 ref., August 2011.
Accurate predictions of the soil-gas diffusivity (Dp/Do where Dp is the soil-gas diffusion coefficient and Do is the diffusion coefficient in free air) from easily measureable parameters like air-filled porosity (e) and soil total porosity (f) are valuable when predicting soil aeration and the emission of greenhouse gases and gaseous-phase contaminants from soils. Soil type (texture) and soil density (compaction) are two key factors controlling gas diffusivity in soils. We extended a recently presented density-corrected Dp(e)/Do model by letting both model parameters (a and b) be interdependent and also functions of f. The extension was based on literature measurements on Dutch and Danish soils ranging from sand to peat. The parameter a showed a promising linear relation to total porosity, while b also varied with a following a weak linear relation. The thus generalized density-corrected (GDC) model gave improved predictions of diffusivity across a wide range of soil types and density levels when tested against two independent data sets (total of 280 undisturbed soils or soil layers) representing Danish soil profile data (0-8 m below the ground surface) and performed better than existing models. The GDC model was further extended to describe two-region (bimodal) soils and could describe and predict Dp/Do well for both different soil aggregate size fractions and variably compacted volcanic ash soils. A possible use of the new GDC model is engineering applications such as the design of highly compacted landfill site caps.
DOI: 10.2136/sssaj2010.0405
12017403 Francelino, Marcio Rocha (Universidade Federal Rural do Rio de Janeiro, Departamento de Silvicultura, Rio de Janeiro, Brazil); Schaefer, Carlos Ernesto G. R.; Simas, Felipe Nogueira Bello; Fernandes Filho, Elpidio Inacio; de Souza, Jose Joao Lelis Leal and da Costa, Liovando Marciano. Geomorphology and soils distribution under paraglacial conditions in an ice-free area of Admiralty Bay, King George Island, Antarctica: Catena (Giessen), 85(3), p. 194-204, illus. incl. 3 tables, geol. sketch maps, 37 ref., June 2011.
The main pedological, geomorphological and cryogenic features of Keller Peninsula, part of Admiralty Bay, King George Island, Maritime Antarctica, were mapped and quantified with emphasis on the relationship between the ice retreat process, melt-out, landform development and soil distribution. Moraines, protalus, scree slopes, inactive glacial cirques, uplift marine terraces, biogenic landforms, aretes and Felsenmeer were mapped. Scree slope is the main landform, covering approximately 25% of the peninsula, indicating prominent paraglacial features. Inherited, glacial landforms, such as lateral moraines, highland plateau and exhumed U shaped-valleys, are now being exposed in north Keller by ice shrinkage of former ice protecting cover. Landforms influenced soil formation and stability. Cryosols and Leptosols (WRB) roughly corresponding to Gelisols and Entisols (SSS), respectively, are the most common soil classes, with an overall tendency of absent permafrost in the coastal areas, changing to sporadic permafrost at mid-slope, and discontinuous permafrost with greater altitude and substrate stability.
DOI: 10.1016/j.catena.2010.12.007
12020085 Lana-Renault, Noemi (Universidad de La Rioja, Departamento de Ciencias Humanas, Logrono, Spain); Alvera, Bernardo and García-Ruiz, José M. Runoff and sediment transport during the snowmelt period in a Mediterranean high-mountain catchment: Arctic, Antarctic, and Alpine Research, 43(2), p. 213-222, illus. incl. 2 tables, sketch map, 60 ref., May 2011.
The hydrological and geomorphic functioning of high-mountain catchments is heavily influenced by snow accumulation and melt processes, which condition the timing and characteristics of discharges, solute outputs, and suspended sediment and bedload transport. We report here the transport of suspended sediment and solutes during the snowmelt period in a small experimental catchment in the subalpine belt of the Central Spanish Pyrenees. The seasonality of hydrological and sediment responses throughout the year was investigated using daily data of discharge, suspended sediment transport and solute outputs of the hydrological years 2003/2004 and 2005/2006. The study demonstrated the importance of the snowmelt period in terms of runoff production, and solute and suspended sediment yield: whereas precipitation during the snowmelt period (2-2.5 months) represented 10-13% of annual precipitation, discharge and suspended sediment transport accounted for up to 50% and 60%, respectively, and solute output approximately 40-50%. Solute transport dominated throughout the snowmelt period, whereas suspended sediment transport mostly occurred during the second phase of the snowmelt period (June), when an expanding area of the catchment was free from snow. The moderate daily increases in discharge, which were related to day-night temperature fluctuations, were insufficient to transport bedload material. Hourly data were used for preliminary assessment of the relationships among discharge, suspended sediment, and solute concentration, which provided insights into sediment sources and delivery mechanisms. Thus, during snowmelt-related events, the sediment mobilized was most probably derived from areas near or within the channel. In contrast, during events involving both snowmelt and rainfall, the gully system near the divide contributed to sediment load. The solute concentration was inversely related to water discharge, with higher concentrations during the first half of the snowmelt period (May) than during the second half (June). The results of this study demonstrate the key role of snow accumulation and melting processes in controlling the hydrological dynamics and patterns of particulate and solute mobilization in high-mountain environments. Future changes in snow volume and duration will affect the timing of snowmelt-related spring high flows, as well as soil erosion and transport.
DOI: 10.1657/1938-4246-43.2.213
12012231 Famiglietti, J. S. (University of California, Irvine, Center for Hydrologic Modeling, Irvine, CA); Lo, M.; Ho, S. L.; Bethune, J.; Anderson, K. J.; Syed, T. H.; Swenson, S. C.; de Linage, C. R. and Rodell, M. Satellites measure recent rates of groundwater depletion in California's Central Valley: Geophysical Research Letters, 38(3), Citation L03403, illus. incl. 1 table, sketch map, 25 ref., 2011.
In highly productive agricultural areas such as California's Central Valley, where groundwater often supplies the bulk of the water required for irrigation, quantifying rates of groundwater depletion remains a challenge owing to a lack of monitoring infrastructure and the absence of water use reporting requirements. Here we use 78 months (October 2003-March 2010) of data from the Gravity Recovery and Climate Experiment satellite mission to estimate water storage changes in California's Sacramento and San Joaquin River Basins. We find that the basins are losing water at a rate of 31.0 ± 2.7 mm yr-1 equivalent water height, equal to a volume of 30.9 km3 for the study period, or nearly the capacity of Lake Mead, the largest reservoir in the United States. We use additional observations and hydrological model information to determine that the majority of these losses are due to groundwater depletion in the Central Valley. Our results show that the Central Valley lost 20.4 ± 3.9 mm yr-1 of groundwater during the 78-month period, or 20.3 km3 in volume. Continued groundwater depletion at this rate may well be unsustainable, with potentially dire consequences for the economic and food security of the United States.
DOI: 10.1029/2010GL046442
12020660 Riskus, Vaidutis. Po skaistgirio apylinkes pasidairius [A glance at the Skaistgirys area]: Geologijos Akiraciai, 2011(1-2), p. 51-52, illus., 3 ref., 2011.
12017045 Mann, Daniel H. (University of Alaska-Fairbanks, Geography Program, Fairbanks, AK); Groves, Pamela; Reanier, Richard E. and Kunz, Michael L. Floodplains, permafrost, cottonwood trees, and peat; what happened the last time climate warmed suddenly in arctic Alaska?: Quaternary Science Reviews, 29(27-28), p. 3812-3830, illus. incl. sect., 2 tables, sketch map, 103 ref., December 2010. Includes appendices.
We use the stratigraphy of floodplains on Alaska's North Slope to describe how tundra watersheds responded to climate changes over the last 15,000 calibrated years BP (15 cal ka BP). Two episodes of extremely rapid floodplain alluviation occurred during the Pleistocene-Holocene transition, one between 14 and 12.8 cal ka BP and the other between 11.5 and 9.5 cal ka BP. These aggradation episodes coincided with periods of warming in summer when cottonwood (Populus balsamifera L.) expanded its range, peatlands became established, and widespread thermokarst occurred. The two aggradation episodes were separated by a period of floodplain incision during the Younger Dryas under cooler and possibly drier conditions. At times of increasing summer warmth, melting permafrost and enhanced precipitation probably triggered widespread mass wasting on hillslopes that overwhelmed the capacity of streams to transport sediment downstream, and rapid floodplain aggradation resulted. After peatlands became widespread in the early Holocene, rivers slowly incised their valley fills. Because major pulses of sediment input were limited to times of rapid thaw and increasing moisture, many floodplains on the North Slope have been effectively decoupled from upstream hillslopes for much of the past 15,000 years. Our findings: (a) confirm the sensitivity of arctic watersheds to rapid warming in summer, (b) emphasize the importance of hillslope mass wasting in landscape-scale responses to climate change, and (c) suggest that the presence of peatland on this arctic landscape today has raised its geomorphic response threshold to climate warming compared to what it was 14,000 years ago.
DOI: 10.1016/j.quascirev.2010.09.002
12017040 Meyer, Hanno (Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, Potsdam, Germany); Schirrmeister, Lutz; Andreev, Andrei; Wagner, Dirk; Hubberten, Hans W.; Yoshikawa, Kenji; Bobrov, Anatoly; Wetterich, Sebastian; Opel, Thomas; Kandiano, Evgeniya and Brown, Jerry. Late glacial and Holocene isotopic and environmental history of northern coastal Alaska; results from a buried ice-wedge system at Barrow: Quaternary Science Reviews, 29(27-28), p. 3720-3735, illus. incl. sect., 5 tables, sketch map, 75 ref., December 2010.
Barrow, the northernmost point in Alaska, is one of the most intensively studied areas in the Arctic. However, paleoenvironmental evidence is limited for northern Alaska for the Lateglacial-Holocene transition. For a regional paleoenvironmental reconstruction, we investigated a permafrost ice-wedge tunnel near Barrow, Alaska. The studied site was first excavated in the early 1960s and intercepts a buried ice-wedge system at 3-6 m depth below the surface. A multi-methodological approach was applied to this buried ice-wedge system and the enclosing sediments, which in their combination, give new insight into the Late Quaternary environmental and climate history. Results of geochronological, sedimentological, cryolithological, paleoecological, isotope geochemical and microbiological studies reflect different stages of mid to late Wisconsin (MW to LW), Allerod (AD), Younger Dryas (YD), Preboreal (PB), and Late Holocene paleoenvironmental evolution. The LW age of the site is indicated by AMS dates in the surrounding sediments of 21.7 kyr BP at the lateral contact of the ice-wedge system as well as 39.5 kyr BP below the ice-wedge system. It is only recently that in this region, stable isotope techniques have been employed, i.e. to characterize different types of ground ice. The stable isotope record (oxygen: d18O; hydrogen: dD) of two intersecting ice wedges suggests different phases of the northern Alaskan climate history from AD to PB, with radiocarbon dates from 12.4 to 9.9 kyr BP (ranging from 14.8 to 10.6 kyr cal BP). Stable isotope geochemistry of ice wedges reveals winter temperature variations of the Lateglacial-Holocene transition including a prominent YD cold period, clearly separated from the warmer AD and PB phases. YD is only weakly developed in summer temperature indicators (such as pollen) for the northern Alaska area, and by consequence, the YD cold stadial was here especially related to the winter season. This highlights that the combination of winter and summer indicators comprehensively describes the seasonality of climate-relevant processes in discrete time intervals. The stable isotope record for the Barrow buried ice-wedge system documents for the first time winter climate change at the Lateglacial-Holocene transition continuously and at relatively high (likely centennial) resolution.
DOI: 10.1016/j.quascirev.2010.08.005
12017046 Weijers, Stef (Vrije Universiteit Amsterdam, Institute of Ecological Science, Department of Systems Ecology, Institute of Ecological Science, Amsterdam, Netherlands); Broekman, Rob and Rozema, Jelte. Dendrochronology in the High Arctic; July air temperatures reconstructed from annual shoot length growth of the circum-arctic dwarf shrub Cassiope tetragona: Quaternary Science Reviews, 29(27-28), p. 3831-3842, illus. incl. 4 tables, sketch map, 44 ref., December 2010.
The instrumental Arctic climate record is both temporally and spatially limited. Therefore, there is a need for reliable climate proxies to increase knowledge of past and future Arctic climate change. Annual shoot length increase of the circumarctic dwarf shrub species Cassiope tetragona represents such a new climate proxy. We measured annual shoot length increase of 32 plant samples of the circumarctic dwarf shrub species C. tetragona using the presence of wintermarksepta within the stems, resulting in a 169 year growth chronology (1840-2008) for a High Arctic site on Svalbard. This is the longest growth chronology for dwarf shrub species produced up to now. Relationships between climate and Cassiope growth were investigated through correlative, response function and forward stepwise multiple regression analysis. July average air temperature was found to be the most important factor determining growth, by itself capable of explaining 41% of the variance in shoot growth between 1912 and 2008. The second best predictors were previous year September precipitation sums and average air temperatures, along with several previous growth parameters. A multiple regression model explaining growth with current July and previous year September temperature, combined with previous growth of lag 1, 2 and 5 years as predictors explains 70% of the observed variance in growth. July temperatures and previous year September precipitation sums alone explain 59% of the variance in standardized growth. Mean July air temperature was reconstructed for the period between 1876 and 2007 by a growth-temperature transfer model, using current and following year's growth. The estimated temperatures correlated well with measured temperatures over the calibration (1912-1959) and verification (1960-2007) period: R2=0.34 and R2=0.47, respectively. The instrumental record (1912-2008) extended with these reliable mean July temperature estimates (1876-1911) reveals a significant warming trend on Svalbard since 1876 of 0.07°C decade-1 on average. This study shows that the climate-growth relationships in C. tetragona, its longevity, its annual resolution, the availability of (sub)fossil fragments in tundra soil cores and its circumartic distribution make it a very valuable tool for climate reconstructions beyond the instrumental record and in areas lacking meteorological data, throughout the Arctic.
DOI: 10.1016/j.quascirev.2010.09.003
12016970 Pons-Branchu, Edwige (Université Aix-Marseille III, CEREGE, Aix-en-Provence, France); Hamelin, Bruno; Losson, Benoit; Jaillet, Stéphane and Brulhet, Jacques. Speleothem evidence of warm episodes in northeast France during Marine Oxygen Isotope Stage 3 and implications for permafrost distribution in northern Europe: Quaternary Research, 74(2), p. 246-251, illus. incl. 2 tables, sketch map, 51 ref., September 2010.
U-Th ages have been obtained by TIMS on the growth periods of a stalagmite from the "Grotte des Puits de Pierre-la-Treiche" (northeastern France), during the middle part of the "Weichselian glaciation" (Marine Isotope Stage 3), between 55.36±0.95 and 53.34±0.49 ka and around 45.85±0.49 ka. These episodes are contemporaneous with abrupt climatic variations recorded in Greenland ice cores (Greenland interstadials 12, 14 and 15) that have been previously recognized in European speleothems. They also coincide with two interstadials, known as "Goulotte" and "Pile" in the Grande Pile pollen sequence (eastern France), which have been correlated with the Moershoofd complex in the Netherlands. Such evidence of speleothem deposition related to temperate episodes gives a strong indication of the absence of continuous shallow permafrost during the middle part of MIS 3 in northeastern France.
DOI: 10.1016/j.yqres.2010.06.007
12013409 Callaghan, Terry V. (Royal Swedish Academy of Sciences, Abisko Scientific Research Station, Abisko, Sweden); Bergholm, Fredrik; Christensen, Torben R.; Jonasson, Christer; Kokfelt, Ulla and Johansson, Margareta. A new climate era in the sub-Arctic; accelerating climate changes and multiple impacts: Geophysical Research Letters, 37(14), Citation L14705, illus. incl. 4 tables, 28 ref., 2010. Supplemental information/data is available in the online version of this article.
Climate warming in the Swedish sub-Arctic since 2000 has reached a level at which statistical analysis shows for the first time that current warming has exceeded that in the late 1930's and early 1940's, and has significantly crossed the 0°C mean annual temperature threshold which causes many cryospheric and ecological impacts. The accelerating temperature increase trend has driven similar trends in the century-long increase in snow thickness, loss of lake ice, increases in active layer thickness, lake water TOC (total organic carbon) concentrations and the assemblages of diatoms, and changes in tree-line location and plant community structure. Some of these impacts were not evident in the first warm period of the 20th Century. Changes in climate are associated with reduced temperature variability, particularly loss of cold winters and cool summers, and an increase in extreme precipitation events that cause mountain slope instability and infrastructure failure. The long term records of multiple, local environmental factors compiled here for the first time provide detailed information for adaptation strategy development while dramatic changes in an environment particularly vulnerable to climate change highlight the need to adopt global mitigation strategies.
DOI: 10.1029/2009GL042064
12017011 Cannone, Nicoletta (Ferrara University, Department of Biology and Evolution, Ferrara, Italy); Lewkowicz, Antoni G. and Guglielmin, Mauro. Vegetation colonization of permafrost-related landslides, Ellesmere Island, Canadian High Arctic: Journal of Geophysical Research, 115(G4), Citation G04020, illus. incl. 2 tables, sketch map, 51 ref., 2010.
Relationships between vegetation colonization and landslide disturbance are analyzed for 12 active-layer detachments of differing ages located in three areas of the Fosheim Peninsula, Ellesmere Island (80°N). We discuss vegetation as an age index for landslides and a way to assess the time needed for complete recolonization of the surfaces since landslide detachment. Vegetation on undisturbed terrain is similar in the three areas but is more highly developed and complex inland due to a warmer summer climate. On a regional scale, the location of the area is as important as the effect of landslide age on vegetation colonization because of the influence of mesoclimatic conditions on vegetation development. On a landscape scale, there is a positive relationship between landslide age and vegetation development, as represented by total vegetation cover, floristic composition, and successional stage. Consequently, vegetation can be used at this scale as an indicator of landslide age. Fifty years are required to restore vegetation patches to a floristic composition similar to communities occurring in undisturbed conditions, but with lower floristic richness and a discontinuous cover and without well-developed layering. The shorter time needed for landslide recovery in the area with the warmest summer climate confirms the sensitivity of arctic vegetation to small differences in air temperature. This could trigger a set of interlinked feedbacks that would amplify future rates of climate warming.
DOI: 10.1029/2010JG001384
12017909 Gallois, R. W. (92 Stoke Valley Road, Exeter, United Kingdom). Large-scale periglacial creep fold in Jurassic mudstone on the Dorset coast, UK: Proceedings of the Ussher Society, 12, Part 3, p. 223-232, illus. incl. sects., geol. sketch maps, 21 ref., 2010.
The unglaciated part of southern England was subject to periglacial climates that lasted for more than 20 ka on at least eight occasions during the last 750 ka. There are large outcrops of Jurassic mudstones in south-west England, principally the Lias Group and the Oxford Clay and Kimmeridge Clay formations, and extensive exposures of these beds in the cliffs on the Dorset coast. Notwithstanding the susceptibility of this type of mudstone to permafrost damage and deformation, there is no published record of large-scale folding in the region that has been attributed to periglacial disturbance. Three examples of folding are described here, in the Lias Group at Charmouth and Seatown in west Dorset, and in the Kimmeridge Clay on the Isle of Portland that are attributed to intermittent downhill creep of surface layers up to 20 m thick when in a partially frozen condition. The style of folding in the mudstones and the geometry of the disturbed deposits indicates that they are not tectonic in origin, nor were they formed by valley bulging or landsliding. These are the first large-scale structures of their kind to be recorded in southern England: similar folds elsewhere have been interpreted as valley bulges or tectonic in origin. At the Seatown and the Isle of Portland localities, the deformed mudstones have been preserved beneath younger landslides. The absence of similar structures elsewhere on the Dorset coast is attributed to the rapid removal of similarly weakened materials by marine erosion at times of high sea level during the last c. 6000 years.
12017003 Kane, Evan S. (Michigan Technological University, School of Forest Resources and Environmental Science, Houghton, MI); Turetsky, Merritt R.; Harden, Jennifer W.; McGuire, A. David and Waddington, James M. Seasonal ice and hydrologic controls on dissolved organic carbon and nitrogen concentrations in a boreal-rich fen: Journal of Geophysical Research, 115(G4), Citation G04012, illus. incl. 4 tables, 106 ref., 2010.
Boreal wetland carbon cycling is vulnerable to climate change in part because hydrology and the extent of frozen ground have strong influences on plant and microbial functions. We examined the response of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) across an experimental manipulation of water table position (both raised and lowered water table treatments) in a boreal-rich fen in interior Alaska. DOC and TDN responses to water table manipulation exhibited an interaction with seasonal ice dynamics. We observed consistently higher DOC and TDN concentrations in the lowered water table treatment (71.7 ± 6.5 and 3.0 ± 0.3 mg-L) than in both the control (55.6 ± 5.1 and 2.3 ± 0.2 mg-L) and raised (49.1 ± 4.3 and 1.9 ± 0.1 mg L-1, respectively) water table treatments. Across all plots, pore water DOC concentrations at 20 cm increased as the depth to water table increased (R2 = 0.43, p < 0.001). DOC concentrations also increased as the seasonal thaw depth increased, with solutes increasing most rapidly in the drained plot (R2 = 0.62, p < 0.001). About half of the TDN pool was composed of dissolved organic N (DON). Inorganic N and DON were both highly correlated with changes in DOC, and their respective constraints to mineralization are discussed. These results demonstrate that a declining water table position and dryer conditions affect thaw depth and peat temperatures, and interactions among these ecosystem properties will likely increase DOC and TDN loading and potential for export in these systems.
DOI: 10.1029/2010JG001366
12017002 Lohila, Annalea (Finnish Meteorological Institute, Climate Change Research, Helsinki, Finland); Minkkinen, Kari; Laine, Jukka; Savolainen, Ilkka; Tuovinen, Juha-Pekka; Korhonen, Lauri; Laurila, Tuomas; Tietavainen, Hanna and Laaksonen, Ari. Forestation of boreal peatlands; impacts of changing albedo and greenhouse gas fluxes on radiative forcing: Journal of Geophysical Research, 115(G4), Citation G04011, illus. incl. 3 tables, 65 ref., 2010.
We estimated the magnitude of the radiative forcing (RF) due to changes in albedo following the forestation of peatlands, and calculated the net RF by taking into account the changes in both the albedo and the greenhouse gas (GHG) fluxes during one forest rotation. Data on radiation, tree biomass, and soil GHG fluxes were combined with models for canopy cover, tree carbon accumulation, and the RF due to increased atmospheric GHG concentrations for four typical site cases in Finland covering two soil nutrient levels in the south and north of the country. We also studied the observed long-term surface temperatures to detect any indications of drainage-induced effects. The magnitude of the albedo-induced RF was similar to that caused by the carbon sequestration of the growing trees. At three site cases out of four the drainage induced a cooling or negative RF, the tendency for cooling being higher at sites with a higher nutrient level. The differences in albedo-induced RF mainly arose from the spring season due to (1) the different snow cover duration in the south versus the north, and (2) the different albedos of drained and undrained snow covered peatlands. An increase in the maximum daily temperatures was observed in April in southern Finland, where the most intensive drainage practices have taken place, suggesting that forestry drainage has potentially affected the local climate. Our results show that the decreasing albedo resulting from peatland forestation contributes significantly to the RF, balancing out or even exceeding the cooling effect due to the changing GHG fluxes.
DOI: 10.1029/2010JG001327
12017025 Notaro, Michael (University of Wisconsin-Madison, Center for Climatic Research, Madison, WI); Liu, Zhengyu; Gallimore, Robert G.; Williams, John W.; Gutzler, David S. and Collins, Scott. Complex seasonal cycle of ecohydrology in the Southwest United States: Journal of Geophysical Research, 115(G4), Citation G04034, illus. incl. 2 tables, sketch map, 111 ref., 2010.
This study investigates the causes for, and distribution of, unimodal versus bimodal seasonal cycle of vegetation greenness in the Southwest United States using extensive site observations, climate data, satellite data, and the Lund-Potsdam-Jena (LPJ) vegetation model. Peak vegetation greenness is achieved in a clockwise manner across the Southwest, beginning in spring in the Sonoran Desert following winter rains, then in Utah-Colorado with snowmelt/summer rains, and finally in New Mexico-eastern Arizona with late summer monsoon rains. At high elevations, spring-summer snowmelt is critical for supplying the necessary soil moisture to trigger vegetation growth. A bimodal seasonal cycle of vegetation greenness is evident in satellite data and LPJ simulations across eastern Arizona and western New Mexico, characterized by peaks during late spring-early summer and late summer-early autumn. This bimodal green-up remains a pressing paradox for which many competing hypotheses exist. The mechanism for this seasonal pattern is demonstrated using LPJ and observational data and is found to deviate from the traditional pulse-reserve paradigm. This paradigm states that rainfall events in arid lands produce nearly immediate pulses of vegetation growth and accumulation of reserves but does not consider cold dormancy, time-lagged vegetation responses, or rainfall seasonality. The following soil moisture based mechanism for bimodal greening is proposed. The initial peak in vegetation greenness during late spring-early summer results from a break in cold dormancy and benefits from the gradual winter-long accumulation of deep soil moisture from weak synoptic rain events and snowmelt in colder regions. Limited precipitation and ongoing transpiration, from the initial vegetation greening, trigger a midsummer drying of the soil and a consequential minimum in vegetation activity. Later, pulses of monsoon rainfall in late summer-early autumn support the secondary greening, although significant runoff of brief, intense rainstorms and substantial soil evaporation limit moisture to the upper soil layers.
DOI: 10.1029/2010JG001382
12017006 Yi Shuhua (Cold and Arid Regions Environmental and Engineering Research Institute, State and Key Laboratory of Cryosphere Sciences,Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); McGuire, A. David; Kasischke, Eric; Harden, Jennifer W.; Manies, Kristen; Mack, Michelle and Turetsky, Merritt R. A dynamic organic soil biogeochemical model for simulating the effects of wildfire on soil environmental conditions and carbon dynamics of black spruce forests: Journal of Geophysical Research, 115(G4), Citation G04015, illus. incl. 2 tables, 77 ref., 2010. Includes 4 appendices.
Ecosystem models have not comprehensively considered how interactions among fire disturbance, soil environmental conditions, and biogeochemical processes affect ecosystem dynamics in boreal forest ecosystems. In this study, we implemented a dynamic organic soil structure in the Terrestrial Ecosystem Model (DOS-TEM) to investigate the effects of fire on soil temperature, moisture, and ecosystem carbon dynamics. DOS-TEM consists of environmental, ecological, disturbance effects, and dynamic organic soil modules. Changes in organic layer thickness are computed from calculated changes in carbon pools following fire and during stand succession. DOS-TEM was parameterized based on studies reported in the literature and evaluated independently at sites in interior Alaska. This evaluation reveals that (1) DOS-TEM is capable of accurately simulating the thickness and carbon content of organic soils; and (2) without the dynamic linkage between soil organic thickness and carbon content, the model overestimates soil carbon in deep mineral soil horizons of dry black spruce ecosystems of interior Alaska. Sensitivity tests were performed to investigate issues related to spatial heterogeneity of carbon dynamics including soil drainage and fire frequency. Results show that both soil drainage and fire frequency are important in the carbon dynamics simulated by DOS-TEM, and should be considered in spatial applications of the model.
DOI: 10.1029/2010JG001302
|
|
12020404 Howari, F. M.; Sadiq, A. M. and Al-Thani, R. Pathways and possible impacts of accidental CO2 subsurface leak in sabkha's environment, Qatar [abstr.]: in GEO 2010 abstracts; Part III, GeoArabia (Manama), 16(3), p. 211, 2011. Meeting: Ninth Middle East geosciences exhibition and conference, March 7-10, 2010, Bahrain.
12020145 Ivanov, B. A. (Russian Academy of Sciences, Institute for Dynamics of Geospheres, Moscow, Russian Federation) and Pierazzo, E. Ice-rock mixture Hugoniot; numerical modeling: 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, 2185, illus., 12 ref., 2011. Meeting: Forty-second lunar and planetary science conference, March 7-11, 2011, Woodlands, TX. Accessed on Dec. 5, 2011.
URL: http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2185.pdf
12015306 Starkel, L. (Institute of Geography, Cracow, Poland). Shifting of climatic-vegetation belts in Eurasian mountains and their expression in slope evolution: in Il ruolo della geomorfologia nella gestione del territorio (Universita di Modena e Reggio Emilia), Geografia Fisica e Dinamica Quaternaria (Testo Stampato), 34(1), p. 33-43, illus., 87 ref., 2011. Meeting: III convegno nazionale AlGeo in onore del Prof. Mario Panizza, Sept. 13-18, 2009, Modena, Italy.
Climatic, vegetation vertical zones controlled mainly by changes in the temperature, shifting in the Quaternary, decide on the rate and direction of slope evolution. In the Eurasian Mountains beside vertical displacement of geomorphic processes during cold stages a pronounced role was played by expansion of permafrost in western direction. The limits of vertical zones of geomorphic processes are frequently adapted to inherited features of relief and especially to relief energy. High rate of uplift cause accelerated incision of valleys and large slope failures, it may be more important than the secular processes acting in various climatic vertical zones. The mountain glaciers during advances separate valley sides into supraglacial, paraglacial and subglacial sectors.
12017103 Sjostedt, C. (Royal Institute of Technology, Stockholm, Sweden); Gustafsson, J. P.; Persson, I.; Kleja, D. B.; Hassellov, M. and Borg, H. Iron phases in soils and softwater lakes as determined by EXAFS spectroscopy [abstr.]: in Abstracts of the 20th annual V. M. Goldschmidt conference, Geochimica et Cosmochimica Acta, 74(12, Suppl. 1), p. A969, 2 ref., 2010. Meeting: 20th annual V. M. Goldschmidt conference, June 13-18, 2010, Knoxville, TN.
URL: http://goldschmidt2010.org/abstracts/A-Z+Index.pdf
12017164 Struyf, Eric (University of Antwerp, Department of Biology, Wilrijk, Belgium); Kokfelt, Ulla; Smis, Adriaan; Conley, Daniel J.; Humborg, Christoph; Mörth, Carl-Magnus; Vandevenne, Floor and Meire, Patrick. Interactions between climate change, land use and the biological silica buffer in wetlands and forests [abstr.]: in Abstracts of the 20th annual V. M. Goldschmidt conference, Geochimica et Cosmochimica Acta, 74(12, Suppl. 1), p. A999, 2010. Meeting: 20th annual V. M. Goldschmidt conference, June 13-18, 2010, Knoxville, TN.
URL: http://goldschmidt2010.org/abstracts/A-Z+Index.pdf
12018354 Xu, Jianfeng (J. P. Kenny, Houston, TX); Eltaher, Ayman and Jukes, Paul. Warm pipeline in permafrost; a sensitivity study of the major thermal properties: in Proceedings of the ASME 29th international conference on Ocean, offshore and arctic engineering; Volume 4, Ocean engineering, polar and arctic sciences and technology (Chen Gang, chairperson; et al.), International Conference on Offshore Mechanics and Arctic Engineering, 29(Volume 4), p. 793-799, illus. incl. 1 table, 8 ref., 2010. Meeting: 29th international conference on Ocean, offshore and arctic engineering, June 6-11, 2010, Shanghai, China. Paper OMAE2010-20495.
12016655 Ablyazina, D. (Moscow State University, Department of Geography, Moscow Russian Federation, Moscow, Russian Federation); Boitsov, A.; Grebenets, V.; Kaverin, D.; Kleine, A.; Kurchatova, A.; Pfeiffer, E. M.; Zschocke, A.; Shiklomanov, N. and Streletskiy, D. International permafrost field courses in Siberia; the synthesis of research and education [abstr.]: in European Geosciences Union general assembly 2009, Geophysical Research Abstracts, 11, EGU2009-730-3, 2009. Meeting: European Geosciences Union general assembly 2009, April 19-24, 2009, Vienna, Austria.
12019336 Balks, M. R. (University of Waikato, Department of Earth and Ocean Sciences, Hamilton, New Zealand); Adlam, L. S.; Seybold, C. A.; Aislabie, J. and Campbell, D. I. Temporal and spatial variation in active layer depth in the McMurdo Sound region, Antarctica [abstr.]: in 2009 annual Antarctic conference; Sustaining the gains of the International Polar Year, Antarctica New Zealand, Christchurch, New Zealand, p. 39, 2009. Meeting: 2009 annual Antarctic conference; Sustaining the gains of the International Polar Year, July 1-3, 2009, Auckland, New Zealand.
12016697 Bauman, Frank (University of Tuebingen, Institute of Geography, Tuebingen, Germany); He, J. S. and Scholten, T. Pedogenesis and soil moisture, but not soil temperature best explain large-scale patterns of soil carbon and soil nitrogen contents in the permafrost ecosystems of Tibetan alpine grasslands [abstr.]: in European Geosciences Union general assembly 2009, Geophysical Research Abstracts, 11, EGU2009-8988, 2009. Meeting: European Geosciences Union general assembly 2009, April 19-24, 2009, Vienna, Austria.
12016650 Carlson, D. (International Polar Year International Programme Office, Cambridge, United Kingdom). Building information into prediction for the cryosphere [abstr.]: in European Geosciences Union general assembly 2009, Geophysical Research Abstracts, 11, EGU2009-14125, 2009. Meeting: European Geosciences Union general assembly 2009, April 19-24, 2009, Vienna, Austria.
12019340 Carson, N. (University of Canterbury, Department of Geological Sciences, Christchurch, New Zealand); Storey, B.; Shulmeister, J. and Bentley, M. Glacial history of Denton Hills, Antarctica [abstr.]: in 2009 annual Antarctic conference; Sustaining the gains of the International Polar Year, Antarctica New Zealand, Christchurch, New Zealand, p. 80, 1 ref., 2009. Meeting: 2009 annual Antarctic conference; Sustaining the gains of the International Polar Year, July 1-3, 2009, Auckland, New Zealand.
Stability analysis of earth barriers protecting underground mine entries in coal slurry impoundments is commonly conducted by assuming water and sometimes soil pressure on the end of a horizontal failure slice. However, a horizontal failure slice is not necessarily a critical surface and inclined surfaces need to be considered. To address this concern, a two-dimensional rigid body stability analysis is developed for earth barriers that accounts for normal and shear forces on the top and bottom of the failure slice, overburden loading on the failure slice, and normal and shear forces at the barrier-highwall interface. End forces on the failure slice include water pressure and Ko consolidated coal slurry. The minimum safety factor determined with the rigid body analysis shows reasonable agreement with finite element solutions using both mobilized shear stress and strength reduction techniques. The stability analysis demonstrates that previously assumed horizontal failure surfaces are not critical surfaces. Analysis of an example barrier subjected to increasing slurry depth and commensurate pore pressures shows the minimum safety factor increases slightly with increasing slurry depth.
12013349 Collett, Timothy S. (U. S. Geological Survey, Denver, CO). Gas hydrate petroleum systems in marine and arctic permafrost environments: in 29th annual GCSSEPM Foundation Bob F. Perkins research conference; unconventional energy resources; making the unconventional conventional (Carr, Timothy R., editor; et al.), Papers presented at the Gulf Coast Section, Society of Economic Paleontologists and Mineralogists Foundation Annual Bob F. Perkins Research Conference, 29, p. 6-30, illus. incl. sketch map, 31 ref., 2009. compact disc. Meeting: 29th annual GCSSEPM Foundation Bob F. Perkins research conference, Dec. 6-8, 2009, Houston, TX.
12016654 de Jong, Carmen (University of Savory, Mountain Institute, Le Bourget du Lac, France). Introduction to outreach and education in the cryosphere [abstr.]: in European Geosciences Union general assembly 2009, Geophysical Research Abstracts, 11, EGU2009-14050, 2009. Meeting: European Geosciences Union general assembly 2009, April 19-24, 2009, Vienna, Austria.
12016652 Hinzman, L. D. (University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK). Evidence and consequences of warming and thawing permafrost in response to a warming climate [abstr.]: in European Geosciences Union general assembly 2009, Geophysical Research Abstracts, 11, EGU2009-14138, 2009. Meeting: European Geosciences Union general assembly 2009, April 19-24, 2009, Vienna, Austria.
12016656 Leibman, M. (Russian Academy of Sciences, Siberian Branch, Earth Cryosphere Institute, Moscow, Russian Federation). Field training for permafrost students in the cold-climate conditions [abstr.]: in European Geosciences Union general assembly 2009, Geophysical Research Abstracts, 11, EGU2009-14048, 2009. Meeting: European Geosciences Union general assembly 2009, April 19-24, 2009, Vienna, Austria.
12016657 Lepparanta, M. (University of Helsinki, Department of Physics, Helsinki, Finland). Education in cryosphere science for students and teachers at University of Helsinki [abstr.]: in European Geosciences Union general assembly 2009, Geophysical Research Abstracts, 11, EGU2009-14080, 2009. Meeting: European Geosciences Union general assembly 2009, April 19-24, 2009, Vienna, Austria.
12016661 Streletskaya, I. Permafrost and periglacial geomorphology of Western Taymyr (PPG), Russia [abstr.]: in European Geosciences Union general assembly 2009, Geophysical Research Abstracts, 11, EGU2009-11253, 2009. Meeting: European Geosciences Union general assembly 2009, April 19-24, 2009, Vienna, Austria.
|
