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13057553 Paine, Jeffrey G. (Bureau of Economic Geology, Austin, TX); Andrews, John R.; Saylam, Kutalmis; Tremblay, Thomas A.; Averett, Aaron R.; Caudle, Tiffany L.; Meyer, Thoralf and Young, Michael H. Airborne lidar on the Alaskan North Slope; wetlands mapping, lake volumes, and permafrost features: in Hydrogeophysics (Miller, Rick, prefacer; et al.), Leading Edge (Tulsa, OK), 32(7), p. 798-805, illus., 2 ref., July 2013.
Wetlands and shallow, freshwater lakes are common on the Alaskan North Slope, a permafrost-dominated coastal plain above the Arctic Circle. New approaches are needed to augment traditional remote sensing and ground-based field activities that would enable rapid and accurate discrimination of wetlands from uplands and estimation of lake depths and volumes over areas being considered for exploration and production activities. Using a new airborne lidar instrument that combines laser ranging at near-infrared wavelengths for topography and green wavelengths for bathymetry, we flew a pilot study over a 490-km2 area south of Prudhoe Bay to measure surface topography at a density of about 20 points/m2 and water-body depths at a density of about 2 points/m2. High-resolution digital elevation models, having vertical accuracies of a few centimeters, have been generated from the topographic laser data.
DOI: 10.1190/tle32070798.1
13057462 Krautblatter, Michael (Technische Universität München, Munich, Germany); Funk, Daniel and Gunzel, Friederike K. Why permafrost rocks become unstable; a rock-ice-mechanical model in time and space: Earth Surface Processes and Landforms, 38(8), p. 876-887, illus., 101 ref., June 30, 2013.
In this paper, we develop a mechanical model that relates the destabilization of thawing permafrost rock slopes to temperature-related effects on both, rock- and ice-mechanics; and laboratory testing of key assumptions is performed. Degrading permafrost is considered to be an important factor for rock-slope failures in alpine and arctic environments, but the mechanics are poorly understood. The destabilization is commonly attributed to changes in ice-mechanical properties while bedrock friction and fracture propagation have not been considered yet. However, fracture toughness, compressive and tensile strength decrease by up to 50% and more when intact water-saturated rock thaws. Based on literature and experiments, we develop a modified Mohr-Coulomb failure criterion for ice-filled rock fractures that incorporates fracturing of rock bridges, friction of rough fracture surfaces, ductile creep of ice and detachment mechanisms along rock-ice interfaces. Novel laboratory setups were developed to assess the temperature dependency of the friction of ice-free rock-rock interfaces and the shear detachment of rock-ice interfaces. In degrading permafrost, rock-mechanical properties may control early stages of destabilization and become more important for higher normal stress, i.e. higher magnitudes of rock-slope failure. Ice-mechanical properties outbalance the importance of rock-mechanical components after the deformation accelerates and are more relevant for smaller magnitudes. The model explains why all magnitudes of rock-slope failures can be prepared and triggered by permafrost degradation and is capable of conditioning long para-glacial response times. Here, we present a synoptic rock- and ice-mechanical model that explains the mechanical destabilization processes operating in warming permafrost rocks. Abstract Copyright (2010), John Wiley & Sons, Ltd.
DOI: 10.1002/esp.3374
13053599 Wu Tonghua (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Zhao Lin; Li Ren; Wang, Qinxue; Xie Changwei and Pang Qiangqiang. Recent ground surface warming and its effects on permafrost on the central Qinghai-Tibet Plateau: International Journal of Climatology, 33(4), p. 920-930, illus. incl. 3 tables, 51 ref., March 30, 2013.
In this study, the ground surface temperature (GST) records from 16 meteorological stations, which are located in or adjacent to permafrost regions on the central Qinghai-Tibet Plateau (QTP), are analysed using Mann-Kendal test and Sen's slope estimate methods. We revealed that the GSTs have shown statistically significant warming. On average, mean annual ground surface temperature has increased at a rate of 0.60°C decade-1 over the period of 1980-2007, which is more pronounced than the increase of mean annual air temperature on the plateau. The winter ground surface warming is especially prominent, which is similar to the seasonal trends in changes of air temperature. As important parameters to assess the changes of ground thermal regime in cold regions, surface freezing and thawing indices were also studied. The nonparametric statistic test and estimate indicate that surface freezing and thawing indices both show significant variations (-111.2 and 125.0°C d decade-1, respectively) on the central QTP. The intensive ground surface warming is responsible for the concurrent increase in permafrost temperatures at the long-term observation sites on the plateau. The close correlations between ground surface and permafrost temperatures indicate that the dramatic ground surface warming could have significant influence on the change of permafrost thermal regime in the study region. Abstract Copyright (2012), Royal Meteorological Society.
DOI: 10.1002/joc.3479
13055348 Bosson, Emma (Stockholm University, Department of Physical Geography and Quaternary Geology, Bert Bolin Centre for Climate Research, Stockholm, Sweden); Selroos, Jan-Olof; Stigsson, Martin; Gustafsson, Lars-Goran and Destouni, Georgia. Exchange and pathways of deep and shallow groundwater in different climate and permafrost conditions using the Forsmark Site, Sweden, as an example catchment: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 225-237, illus. incl. 4 tables, geol. sketch maps, 16 ref., February 2013.
This study simulates and quantifies the exchange and the pathways of deep and shallow groundwater flow and solute transport under different climate and permafrost conditions, considering the example field case of the coastal Forsmark catchment in Sweden. A number of simulation scenarios for different climate and permafrost condition combinations have been performed with the three-dimensional groundwater flow and transport model MIKE SHE. Results show generally decreasing vertical groundwater flow with depth, and smaller vertical flow under permafrost conditions than under unfrozen conditions. Also the overall pattern of both the vertical and the horizontal groundwater flow, and the water exchange between the deep and shallow groundwater systems, change dramatically in the presence of permafrost relative to unfrozen conditions. However, although the vertical groundwater flow decreases significantly in the presence of permafrost, there is still an exchange of water between the unfrozen groundwater system below the permafrost and the shallow groundwater in the active layer, via taliks. 'Through taliks' tend to prevail in areas that constitute groundwater discharge zones under unfrozen conditions, which then mostly shift to net recharge zones (through taliks with net downward flow) under permafrost conditions. Copyright 2013 Springer-Verlag Berlin Heidelberg and 2012 Springer-Verlag
DOI: 10.1007/s10040-012-0906-7
13055337 Carey, Sean K. (McMaster University, School of Geography and Earth Sciences, Hamilton, ON, Canada); Boucher, Jessica L. and Duarte, Celina M. Inferring groundwater contributions and pathways to streamflow during snowmelt over multiple years in a discontinuous permafrost subarctic environment (Yukon, Canada): in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 67-77, illus. incl. 3 tables, sketch map, 52 ref., February 2013.
Research on large northern rivers suggests that as permafrost thaws, deeper groundwater flowpaths become active, resulting in greater baseflow, increased concentrations of weathering ions and reduced concentrations of dissolved organic carbon in the streamflow. In contrast, at the headwater-catchment scale, where understanding of groundwater/surface-water interactions is developed, inter-annual variability in climate and hydrology result in complex hydrological and chemical responses to change. This paper reports on a 4-year runoff investigation in an alpine discontinuous permafrost environment in Yukon, Canada, using stable isotopes, major dissolved ions and hydrometric data, to provide enhanced insight into the inter-annual-variability runoff-generation processes. Stable isotope results suggest that pre-event (old) water stored within the catchment dominates the snowmelt hydrograph, and dissolved ion results reveal that groundwater pathways occur predominantly in the near-surface during freshet. Dissolved organic carbon varies inter-annually, reflecting changing melt patterns, whereas weathering ions generated from deeper flowpaths become diluted. The total snow-water equivalent does not have a major influence on the fraction of snowmelt water reaching the stream or the runoff ratio. Results from multiple years highlight the considerable variability over short time scales, limiting our ability to detect climate-change influences on groundwater at the headwater scale. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0920-9
13055333 Cheng Guodong (Chinese Academy of Sciences, Laboratory of Frozen Soils Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China) and Jin Huijun. Permafrost and groundwater on the Qinghai-Tibet Plateau and in northeast China: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 5-23, illus. incl. 8 tables, geol. sketch map, 86 ref., February 2013.
The areal extent of permafrost in China has been reduced by about 18.6% during the last 30 years. Due to the combined influences of climate warming and human activities, permafrost has been degrading extensively, with marked spatiotemporal variability. Distribution and thermal regimes of permafrost and seasonal freeze-thaw processes are closely related to groundwater dynamics. Permafrost degradation and changes in frost action have extensively affected cold-regions hydrogeology. Progress on some research programs on groundwater and permafrost in two regions of China are summarized. On the Qinghai-Tibet Plateau and in mountainous northwest China, permafrost is particularly sensitive to climate change, and the permafrost hydrogeologic environment is vulnerable due to the arid climate, lower soil-moisture content, and sparse vegetative coverage, although anthropogenic activities have limited impact. In northeast China, permafrost is thermally more stable due to the moist climate and more organic soils, but the presence or preservation of permafrost is largely dependent on favorable surface coverage. Extensive and increasing human activities in some regions have considerably accelerated the degradation of permafrost, further complicating groundwater dynamics. In summary, permafrost degradation has markedly changed the cold-regions hydrogeology in China, and has led to a series of hydrological, ecological, and environmental problems of wide concern. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0927-2
13055351 Frampton, Andrew (Stockholm University, Department of Quaternary Geology and Physical Geography, Stockholm, Sweden); Painter, Scott L. and Destouni, Georgia. Permafrost degradation and subsurface-flow changes caused by surface warming trends: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 271-280, illus. incl. 10 tables, 24 ref., February 2013.
Change dynamics of permafrost thaw, and associated changes in subsurface flow and seepage into surface water, are analysed for different warming trends in soil temperature at the ground surface with a three-phase two-component flow system coupled to heat transport. Changes in annual, seasonal and extreme flows are analysed for three warming-temperature trends, representing simplified climate-change scenarios. The results support previous studies of reduced temporal variability of groundwater flow across all investigated trends. Decreased intra-annual flow variability may thus serve as an early indicator of permafrost degradation before longer-term changes in mean flows are notable. This is advantageous since hydrological data are considerably easier to obtain, may be available in longer time series, and generally reflect larger-scale conditions than direct permafrost observations. The results further show that permafrost degradation first leads to increasing water discharge, which then decreases as the permafrost degradation progresses further to total thaw. The most pronounced changes occur for minimum annual flows. The configuration considered represents subsurface discharge from a generic heterogeneous soil-type domain. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0938-z
13055343 Hubbard, S. S. (Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA); Gangodagamage, C.; Dafflon, B.; Wainwright, H.; Peterson, J.; Gusmeroli, A.; Ulrich, C.; Wu, Y.; Wilson, C. J.; Rowland, J.; Tweedie, C. and Wullschleger, S. D. Quantifying and relating land-surface and subsurface variability in permafrost environments using LiDAR and surface geophysical datasets: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 149-169, illus. incl. 2 tables, sketch map, 86 ref., February 2013. Includes appendices.
The value of remote sensing and surface geophysical data for characterizing the spatial variability and relationships between land-surface and subsurface properties was explored in an Alaska (USA) coastal plain ecosystem. At this site, a nested suite of measurements was collected within a region where the land surface was dominated by polygons, including: LiDAR data; ground-penetrating radar, electromagnetic, and electrical-resistance tomography data; active-layer depth, soil temperature, soil-moisture content, soil texture, soil carbon and nitrogen content; and pore-fluid cations. LiDAR data were used to extract geomorphic metrics, which potentially indicate drainage potential. Geophysical data were used to characterize active-layer depth, soil-moisture content, and permafrost variability. Cluster analysis of the LiDAR and geophysical attributes revealed the presence of three spatial zones, which had unique distributions of geomorphic, hydrological, thermal, and geochemical properties. The correspondence between the LiDAR-based geomorphic zonation and the geophysics-based active-layer and permafrost zonation highlights the significant linkage between these ecosystem compartments. This study suggests the potential of combining LiDAR and surface geophysical measurements for providing high-resolution information about land-surface and subsurface properties as well as their spatial variations and linkages, all of which are important for quantifying terrestrial-ecosystem evolution and feedbacks to climate. Copyright 2013 Springer-Verlag Berlin Heidelberg and 2012 Springer-Verlag Berlin Heidelberg (outside the USA)
DOI: 10.1007/s10040-012-0939-y
13055345 Jepsen, S. M. (U. S. Geological Survey, Denver Federal Center, Denver, CO); Voss, C. I.; Walvoord, Michelle A.; Rose, J. R.; Minsley, B. J. and Smith, B. D. Sensitivity analysis of lake mass balance in discontinuous permafrost; the example of disappearing Twelvemile Lake, Yukon Flats, Alaska (USA): in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 185-200, illus. incl. 4 tables, geol. sketch map, 65 ref., February 2013.
Many lakes in northern high latitudes have undergone substantial changes in surface area over the last four decades, possibly as a result of climate warming. In the discontinuous permafrost of Yukon Flats, interior Alaska (USA), these changes have been non-uniform across adjacent watersheds, suggesting local controls on lake water budgets. Mechanisms that could explain the decreasing mass of one lake in Yukon Flats since the early 1980s, Twelvemile Lake, are identified via a scoping analysis that considers plausible changes in snowmelt mass and infiltration, permafrost distribution, and climate warming. Because predicted changes in evaporation (2 cm yr-1) are inadequate to explain the observed 17.5 cm yr-1 reduction in mass balance, other mechanisms are required. The most important potential mechanisms are found to involve: (1) changes in shallow, lateral groundwater flow to the lake possibly facilitated by vertical freeze-thaw migration of the permafrost table in gravel; (2) increased loss of lake water as downward groundwater flow through an open talik to a permeable subpermafrost flowpath; and (3) reduced snow meltwater inputs due to decreased snowpack mass and increased infiltration of snowmelt into, and subsequent evaporation from, fine-grained sediment mantling the permafrost-free lake basin. Copyright 2013 Springer-Verlag Berlin Heidelberg and 2012 Springer-Verlag (outside the USA)
DOI: 10.1007/s10040-012-0896-5
13055335 Kane, Douglas L. (University of Alaska Fairbanks, Institute of Northern Engineering, Fairbanks, AK); Yoshikawa, Kenji and McNamara, James P. Regional groundwater flow in an area mapped as continuous permafrost, NE Alaska (USA): in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 41-52, illus. incl. 3 tables, sketch map, 44 ref., February 2013.
Fundamental knowledge of groundwater systems in areas of permafrost is often lacking. The likelihood of finding good quality groundwater resources of acceptable quantities generally decreases as the areal coverage of permafrost increases. In areas of continuous permafrost, the probability of finding areas of groundwater recharge and discharge are minimal. Still, in northeastern Alaska (USA), the presence of numerous springs and associated downstream aufeis formations clearly indicates that there has to be a groundwater system with the required complementary areas of groundwater recharge and transmission. Recharge zones and transmission pathways in this area of extensive permafrost, however, are essentially unknown. This study shows that the recharge occurs on the south side of the Brooks Range in northeastern Alaska, where extensive limestone outcrops are found. The transmission zone is beneath the permafrost, with discharge occurring through the springs via taliks through the permafrost (where faults are present) and also likely at the northern edge of the permafrost along the Beaufort Sea coast. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0937-0
13055353 McKenzie, Jeffrey M. (McGill University, Earth and Planetary Sciences, Montreal, QC, Canada) and Voss, Clifford I. Permafrost thaw in a nested groundwater-flow system: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 299-316, illus. incl. 1 table, 18 ref., February 2013.
Groundwater flow in cold regions containing permafrost accelerates climate-warming-driven thaw and changes thaw patterns. Simulation analyses of groundwater flow and heat transport with freeze/thaw in typical cold-regions terrain with nested flow indicate that early thaw rate is particularly enhanced by flow, the time when adverse environmental impacts of climate-warming-induced permafrost loss may be severest. For the slowest climate-warming rate predicted by the Intergovernmental Panel on Climate Change (IPCC), once significant groundwater flow begins, thick permafrost layers can vanish in several hundred years, but survive over 1,000 years where flow is minimal. Large-scale thaw depends mostly on the balance of heat advection and conduction in the supra-permafrost zone. Surface-water bodies underlain by open taliks allow slow sub-permafrost flow, with lesser influence on regional thaw. Advection dominance over conduction depends on permeability and topography. Groundwater flow around permafrost and flow through permafrost impact thaw differently; the latter enhances early thaw rate. Air-temperature seasonality also increases early thaw. Hydrogeologic heterogeneity and topography strongly affect thaw rates/patterns. Permafrost controls the groundwater/surface-water-geomorphology system; hence, prediction and mitigation of impacts of thaw on ecology, chemical exports and infrastructure require improved hydrogeology/permafrost characterization and understanding. Copyright 2013 Springer-Verlag Berlin Heidelberg and Springer-Verlag Berlin Heidelberg (outside the USA)
DOI: 10.1007/s10040-012-0942-3
13055346 Quinton, William L. (Wilfrid Laurier University, Centre for Cold Regions and Water Science, Waterloo, ON, Canada) and Baltzer, J. L. The active-layer hydrology of a peat plateau with thawing permafrost (Scotty Creek, Canada): in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 201-220, illus. incl. 1 table, sketch map, 38 ref., February 2013.
The southern margin of permafrost is experiencing unprecedented rates of thaw, yet the effect of this thaw on northern water resources is poorly understood. The hydrology of the active layer on a thawing peat plateau in the wetland-dominated zone of discontinuous permafrost was studied at Scotty Creek, Northwest Territories (Canada), from 2001 to 2010. Two distinct and seasonally characteristic levels of unfrozen moisture were evident in the 0.7-m active layer. Over-winter moisture migration produced a zone of high ice content near the ground surface. The runoff response of a plateau depends on which of the three distinct zones of hydraulic conductivity the water table is displaced into. The moisture and temperature of the active layer steadily rose with each year, with the largest increases close to the ground surface. Permafrost thaw reduced subsurface runoff by (1) lowering the hydraulic gradient, (2) thickening the active layer and, most importantly, (3) reducing the surface area of the plateau. By 2010, the cumulative permafrost thaw had reduced plateau runoff to 47% of what it would have been had there been no change in hydraulic gradient, active layer thickness and plateau surface area over the decade. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0935-2
13055340 Semenova, Olga (Gidrotehproekt, St. Petersburg, Russian Federation); Lebedeva, Liudmila and Vinogradov, Yury. Simulation of subsurface heat and water dynamics, and runoff generation in mountainous permafrost conditions, in the upper Kolyma River basin, Russia: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 107-119, illus. incl. 5 tables, sketch map, 52 ref., February 2013.
The Hydrograph model (a distributed process-based model) was applied to the simulation of soil freeze-thaw and runoff processes, to assess the viability of the model approach and the influence of specific environmental factors in a permafrost environment. Three mountainous permafrost watersheds were studied, at the Kolyma Water Balance Station in north-eastern Russia. The watersheds include rocky talus, mountainous tundra and moist larch-forest landscape regimes, and they were modelled at daily time-steps for the period 1971-1984. Simulated results of soil freeze-thaw depth and runoff showed reasonable agreement with observed values. This study reveals and mathematically describes the dependence of surface and subsurface flow on thawing depth and landscape characteristics. Process analysis and modelling in permafrost regions, including ungauged basins, is suggested, with observable properties of landscapes being used as model parameters, combined with an appropriate level of physically based conceptualization. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0936-1
13055341 Sjoberg, Ylva (Stockholm University, Department of Physical Geography and Quaternary Geology, Stockholm, Sweden); Frampton, Andrew and Lyon, Steve W. Using streamflow characteristics to explore permafrost thawing in northern Swedish catchments: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 121-131, illus. incl. 3 tables, sketch map, 49 ref., February 2013.
The recent and rapid warming of the Arctic leads to thawing of permafrost, which influences and changes subsurface water-flow systems in such landscapes. This study explores the utility of catchments as "sentinels of change" by considering long-term discharge data from 17 stations on unregulated rivers in northern Sweden and analyzing trends in annual minimum discharge and recession flow characteristics. For the catchments considered, the annual minimum discharge has increased significantly (based on the Mann Kendall test at a 95% confidence level) in nine of the catchments and decreased significantly in one catchment. Considering changes in recession-flow characteristics, seven catchments showed significant trends consistent with permafrost thawing while two catchments showed significant trends in the opposite direction. These results are mechanistically consistent with generic physically based modeling studies and the geological setting, as the catchments considered span the spatial limit of permafrost extent. This study illuminates the potential for using hydrologic observations to monitor changes in catchment-scale permafrost. Further, this opens the door for research to isolate the mechanisms behind the different trends observed and to gauge their ability to reflect actual permafrost conditions at the catchment scale. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0932-5
13055338 Utting, Nicholas (University of Ottawa, Department of Earth Science, Ottawa, ON, Canada); Lauriol, Bernard; Mochnacz, Neil; Aeschbach-Hertig, Werner and Clark, Ian. Noble gas and isotope geochemistry in Western Canadian arctic watersheds; tracing groundwater recharge in permafrost terrain: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 79-91, illus. incl. 3 tables, sketch map, 61 ref., February 2013. Supplemental information/data is available in the online version of this article.
In Canada's western Arctic, perennial discharge from permafrost watersheds is the surface manifestation of active groundwater flow systems with features including the occurrence of year-round open water and the formation of icings, yet understanding the mechanisms of groundwater recharge and flow in periglacial environments remains enigmatic. Stable isotopes (d18O, dD, d13CDIC), and noble gases have proved useful to study groundwater recharge and flow of groundwater which discharges along rivers in Canada's western Arctic. In these studies of six catchments, groundwater recharge was determined to be a mix of snowmelt and precipitation. All systems investigated show that groundwater has recharged through organic soils with elevated PCO2, which suggests that recharge occurs largely during summer when biological activity is high. Noble gas concentrations show that the recharge temperature was between 0 and 5°C, which when considered in the context of discharge temperatures, suggests that there is no significant imbalance of energy flux into the subsurface. Groundwater circulation times were found to be up to 31 years for non-thermal waters using the 3H-3He method. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0913-8
13055352 Wellman, Tristan P. (U. S. Geological Survey, Colorado Water Science Center, Lakewood, CO); Voss, Clifford I. and Walvoord, Michelle A. Impacts of climate, lake size, and supra- and sub-permafrost groundwater flow on lake-talik evolution, Yukon Flats, Alaska (USA): in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 281-298, illus. incl. 3 tables, sketch map, 43 ref., February 2013.
In cold regions, hydrologic systems possess seasonal and perennial ice-free zones (taliks) within areas of permafrost that control and are enhanced by groundwater flow. Simulation of talik development that follows lake formation in watersheds modeled after those in the Yukon Flats of interior Alaska (USA) provides insight on the coupled interaction between groundwater flow and ice distribution. The SUTRA groundwater simulator with freeze-thaw physics is used to examine the effect of climate, lake size, and lake-groundwater relations on talik formation. Considering a range of these factors, simulated times for a through-going sub-lake talik to form through 90 m of permafrost range from ~200 to >1,000 years (vertical thaw rates <0.1-0.5 m yr-1). Seasonal temperature cycles along lake margins impact supra-permafrost flow and late-stage cryologic processes. Warmer climate accelerates complete permafrost thaw and enhances seasonal flow within the supra-permafrost layer. Prior to open talik formation, sub-lake permafrost thaw is dominated by heat conduction. When hydraulic conditions induce upward or downward flow between the lake and sub-permafrost aquifer, thaw rates are greatly increased. The complexity of ground-ice and water-flow interplay, together with anticipated warming in the arctic, underscores the utility of coupled groundwater-energy transport models in evaluating hydrologic systems impacted by permafrost. Copyright 2013 Springer-Verlag Berlin Heidelberg and Springer-Verlag Berlin Heidelberg (outside the USA)
DOI: 10.1007/s10040-012-0941-4
13055350 Grenier, Christophe (CNRS-CEA-UVSQ, Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France); Régnier, Damien; Mouche, Emmanuel; Benabderrahmane, Hakim; Costard, François and Davy, Philippe. Impact of permafrost development on groundwater flow patterns; a numerical study considering freezing cycles on a two-dimensional vertical cut through a generic river-plain system: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 257-270, illus. incl. 5 tables, geol. sketch map, 51 ref., February 2013.
The impact of glaciation cycles on groundwater flow was studied within the framework of nuclear waste storage in underground geological formations. The eastern section of the Paris Basin (a layered aquifer with impervious/pervious alternations) in France was considered for the last 120 ka. Cold periods corresponded with arid climates. The issue of talik development below water bodies was addressed. These unfrozen zones can maintain open pathways for aquifer recharge. Transient thermal evolution was simulated on a small-scale generic unit of the landscape including a "river" and "plain". Coupled thermo-hydraulic modeling and simplified conductive heat transfer were considered for a broad range of scenarios. The results showed that when considering the current limited river dimensions and purely conductive heat transfer, taliks are expected to close within a few centuries. However, including coupled advection for flows from the river to the plain (probably pertinent for the eastern Paris Basin aquifer recharge zones) strongly delays talik closure (millennium scale). The impact on regional underground flows is expected to vary from a complete stop of recharge to a reduced recharge, corresponding to the talik zones. Consequences for future modeling approaches of the Paris Basin are discussed. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0909-4
13055347 Painter, Scott L. (Los Alamos National Laboratory, Computational Earth Sciences Group, Earth and Environmental Sciences Division, Los Alamos, NM); Moulton, J. D. and Wilson, C. J. Modeling challenges for predicting hydrologic response to degrading permafrost: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 221-224, illus., 18 ref., February 2013.
DOI: 10.1007/s10040-012-0917-4
13057459 Fischer, Luzia (Geological Survey of Norway, Trondheim, Norway); Huggel, Christian; Kaab, Andreas and Haeberli, Wilfried. Slope failures and erosion rates on a glacierized high-mountain face under climatic changes: Earth Surface Processes and Landforms, 38(8), p. 836-846, illus. incl. sketch map, sect., 59 ref., June 30, 2013.
In this study, rapid topographic changes and increased erosion rates caused by massive slope failures in a glacierized and permafrost-affected high-mountain face were investigated with respect to the current climatic change. The study was conducted at one of the highest periglacial rock faces in the European Alps, the east face of Monte Rosa, Italy. Pronounced changes in ice cover and repeated rock and ice avalanche events have been documented in this rock wall since around 1990. The performed multi-temporal comparison of high-resolution digital terrain models (DTMs) complemented by detailed analyses of repeat photography represents a unique assessment of topographic changes and slope failures over half a century and reveals a total volume loss in bedrock and steep glaciers in the central part of the face of around 25 ´ 106 m3 between 1988 and 2007. The high rock and ice avalanche activity translates into an increase in erosion rates of about one order of magnitude during recent decades. The study indicates that changes in atmospheric temperatures and connected changes in ice cover can induce slope destabilization in high-mountain faces. Analyses of temperature data show that the start of the intense mass movement activity coincided with increased mean annual temperatures in the region around 1990. However, once triggered, mass movement activity seems to be able to proceed in a self-reinforcing cycle, whereby single mass movement events might be strongly influenced by short-term extreme temperature events. The investigations suggest a strong stability coupling between steep glaciers and underlying bedrock, as most bedrock instabilities are located in areas where surface ice has disappeared recently and the failure zones are frequently spatially correlated and often develop from lower altitudes progressively upwards. Abstract Copyright (2010), John Wiley & Sons, Ltd.
DOI: 10.1002/esp.3355
13053990 Wang Junfeng (Chinese Academy of Sciences, State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China) and Wu Qingbai. Annual soil CO2 efflux in a wet meadow during active layer freeze-thaw changes on the Qinghai-Tibet Plateau: Environmental Earth Sciences, 69(3), p. 855-862, illus. incl. 1 table, sketch map, 33 ref., June 2013.
Soil CO2 efflux from an ecosystem responds to the active layer thawing depth (H) significantly. A Li-8100 system was used to monitor the CO2 exchange from a wet meadow ecosystem during a freeze-thaw cycle of the active layer in a permafrost region on the Qinghai-Tibet Plateau. An exponential regression equation (Fsoil/flux = 1.84e0.023H + 5.06 R2 = 0.96) has been established on the basis of observed soil CO2 efflux versus the thawed soil thickness. Using this equation, the total soil CO2 efflux during an annual freeze-thaw cycle has been calculated to be approximately 8.18´1010 mg C. The results suggest that freeze-thaw cycles in the active layer play an important role in soil CO2 emissions and that thawed soil thickness is the major factor controlling CO2 fluxes from the wet meadow ecosystem in permafrost regions on the Qinghai-Tibet Plateau. It can be concluded that with active layer thickening due to permafrost degradation, massive amounts of soil carbon would be emitted as greenhouse gases, and the permafrost region would become a carbon source with a positive feedback effect on climate warming. Hence, more attention should be paid to the influences of the active layer changes on soil carbon emission from these permafrost regions. Copyright 2013 Springer-Verlag Berlin Heidelberg and 2012 Springer-Verlag
DOI: 10.1007/s12665-012-1970-y
13053557 Stolpe, Bjorn (University of Southern Mississippi, Department of Marine Science, Stennis Space Center, MS); Guo, Laodong; Shiller, Alan M. and Aiken, George R. Abundance, size distributions and trace element binding of organic and iron-rich nanocolloids in Alaskan rivers, as revealed by field flow fractionation and ICP-MS: Geochimica et Cosmochimica Acta, 105, p. 221-239, illus. incl. 3 tables, sketch map, 123 ref., March 15, 2013.
Water samples were collected from six small rivers in the Yukon River basin in central Alaska to examine the role of colloids and organic matter in the transport of trace elements in Northern high latitude watersheds influenced by permafrost. Concentrations of dissolved organic carbon (DOC), selected elements (Al, Si, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Ba, Pb, U), and UV-absorbance spectra were measured in 0.45mm filtered samples. 'Nanocolloidal size distributions' (0.5-40 nm, hydrodynamic diameter) of humic-type and chromophoric dissolved organic matter (CDOM), Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb were determined by on-line coupling of flow field-flow fractionation (FFF) to detectors including UV-absorbance, fluorescence, and ICP-MS. Total dissolved and nanocolloidal concentrations of the elements varied considerably between the rivers and between spring flood and late summer base flow. Data on specific UV-absorbance (SUVA), spectral slopes, and the nanocolloidal fraction of the UV-absorbance indicated a decrease in aromaticity and size of CDOM from spring flood to late summer. The nanocolloidal size distributions indicated the presence of different 'components' of nanocolloids. 'Fulvic-rich nanocolloids' had a hydrodynamic diameter of 0.5-3 nm throughout the sampling season; 'organic/iron-rich nanocolloids' occurred in the <8nm size range during the spring flood; whereas 'iron-rich nanocolloids' formed a discrete 4-40 nm components during summer base flow. Mn, Co, Ni, Cu and Zn were distributed between the nanocolloid components depending on the stability constant of the metal (+II)-organic complexes, while stronger association of Cr to the iron-rich nanocolloids was attributed to the higher oxidation states of Cr (+III or +IV). Changes in total dissolved element concentrations, size and composition of CDOM, and occurrence and size of organic/iron and iron-rich nanocolloids were related to variations in their sources from either the upper organic-rich soil or the deeper mineral layer, depending on seasonal variations in hydrological flow patterns and permafrost dynamics. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.gca.2012.11.018
13055334 Callegary, J. B. (U. S. Geological Survey, Arizona Water Science Center, Tucson, AZ); Kikuchi, C. P.; Koch, J. C.; Lilly, M. R. and Leake, S. A. Review; groundwater in Alaska (USA): in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 25-39, illus. incl. geol. sketch maps, 137 ref., February 2013.
Groundwater in the US state of Alaska is critical to both humans and ecosystems. Interactions among physiography, ecology, geology, and current and past climate have largely determined the location and properties of aquifers as well as the timing and magnitude of fluxes to, from, and within the groundwater system. The climate ranges from maritime in the southern portion of the state to continental in the Interior, and arctic on the North Slope. During the Quaternary period, topography and rock type have combined with glacial and periglacial processes to develop the unconsolidated alluvial aquifers of Alaska and have resulted in highly heterogeneous hydrofacies. In addition, the long persistence of frozen ground, whether seasonal or permanent, greatly affects the distribution of aquifer recharge and discharge. Because of high runoff, a high proportion of groundwater use, and highly variable permeability controlled in part by permafrost and seasonally frozen ground, understanding groundwater/surface-water interactions and the effects of climate change is critical for understanding groundwater availability and the movement of natural and anthropogenic contaminants. Copyright 2013 Springer-Verlag Berlin Heidelberg and Springer-Verlag Berlin Heidelberg (outside the USA)
DOI: 10.1007/s10040-012-0940-5
13055344 Gooseff, Michael N. (Pennsylvania State University, Department of Civil and Environmental Engineering, University Park, PA); Barrett, John E. and Levy, Joseph S. Shallow groundwater systems in a polar desert, McMurdo dry valleys, Antarctica: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 171-183, illus. incl. 2 tables, 69 ref., February 2013.
The McMurdo Dry Valleys (MDVs), Antarctica, exist in a hyperarid polar desert, underlain by deep permafrost. With an annual mean air temperature of -18°C, the MDVs receive <10 cm snow-water equivalent each year, collecting in leeward patches across the landscape. The landscape is dominated by expansive ice-free areas of exposed soils, mountain glaciers, permanently ice-covered lakes, and stream channels. An active layer of seasonally thawed soil and sediment extends to less than 1 m from the surface. Despite the cold and low precipitation, liquid water is generated on glaciers and in snow patches during the austral summer, infiltrating the active layer. Across the MDVs, groundwater is generally confined to shallow depths and often in unsaturated conditions. The current understanding and the biogeochemical/ecological significance of four types of shallow groundwater features in the MDVs are reviewed: local soil-moisture patches that result from snow-patch melt, water tracks, wetted margins of streams and lakes, and hyporheic zones of streams. In general, each of these features enhances the movement of solutes across the landscape and generates soil conditions suitable for microbial and invertebrate communities. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0926-3
13055339 Koch, J. C. (U. S. Geological Survey, Alaska Science Center, Anchorage, AK); Ewing, S. A.; Striegl, R. and McKnight, D. M. Rapid runoff via shallow throughflow and deeper preferential flow in a boreal catchment underlain by frozen silt (Alaska, USA): in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 93-106, illus. incl. 3 tables, sketch map, 54 ref., February 2013.
In high-latitude catchments where permafrost is present, runoff dynamics are complicated by seasonal active-layer thaw, which may cause a change in the dominant flowpaths as water increasingly contacts mineral soils of low hydraulic conductivity. A 2-year study, conducted in an upland catchment in Alaska (USA) underlain by frozen, well-sorted eolian silt, examined changes in infiltration and runoff with thaw. It was hypothesized that rapid runoff would be maintained by flow through shallow soils during the early summer and deeper preferential flow later in the summer. Seasonal changes in soil moisture, infiltration, and runoff magnitude, location, and chemistry suggest that transport is rapid, even when soils are thawed to their maximum extent. Between June and September, a shift occurred in the location of runoff, consistent with subsurface preferential flow in steep and wet areas. Uranium isotopes suggest that late summer runoff erodes permafrost, indicating that substantial rapid flow may occur along the frozen boundary. Together, throughflow and deep preferential flow may limit upland boreal catchment water and solute storage, and subsequently biogeochemical cycling on seasonal to annual timescales. Deep preferential flow may be important for stream incision, network drainage development, and the release of ancient carbon to ecosystems. Copyright 2013 Springer-Verlag Berlin Heidelberg and 2012 Springer-Verlag Berlin Heidelberg (outside the USA)
DOI: 10.1007/s10040-012-0934-3
13055349 Vidstrand, Patrik (TerraSolve, Floda, Sweden); Follin, Sven; Selroos, Jan-Olof; Naslund, Jens-Ove and Rhen, Ingvar. Modeling of groundwater flow at depth in crystalline rock beneath a moving ice-sheet margin, exemplified by the Fennoscandian Shield, Sweden: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 239-255, illus. incl. geol. sketch map, 77 ref., February 2013.
On-going geological disposal programs for spent nuclear fuel have generated strong demands for investigation and characterization of deep-lying groundwater systems. Because of the long time scales for which radiological safety needs to be demonstrated in safety assessment applications, an analysis of the hydrogeological performance of the geosphere system during glacial climate conditions is needed. Groundwater flow at depth in crystalline rock during the passage of an ice-sheet margin is discussed based on performed groundwater-flow modeling of two bedrock sites, Forsmark and Laxemar, in the Fennoscandian Shield, Sweden. The modeled ice sheet mimics the Weichselian ice sheet during its last major advance and retreat over northern Europe. The paper elaborates and analyzes different choices of top boundary conditions at the ice sheet-subsurface interface (e.g. ice-sheet thickness and ice-margin velocity) and in the proglacial area (presence or lack of permafrost) and relates these choices to available groundwater-flow-model hydraulic output and prevailing conceptual hydrogeochemical models of the salinity evolution at the two sites. It is concluded that the choice of boundary conditions has a strong impact on results and that the studied sites behave differently for identical boundary conditions due to differences in their structural-hydraulic properties. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0921-8
13053539 Stolpe, Bjorn (University of Southern Mississippi, Department of Marine Science, Stennis Space Center, MS); Guo, Laodong and Shiller, Alan M. Binding and transport of rare earth elements by organic and iron-rich nanocolloids in Alaskan rivers, as revealed by field flow fractionation and ICP-MS: Geochimica et Cosmochimica Acta, 106, p. 446-462, illus. incl. 1 table, 103 ref., April 1, 2013.
Water samples were collected from six small rivers in the Yukon River basin in central Alaska to examine the role of nanocolloids (0.5-40 nm) in the dynamics and transport of rare earth elements (REEs) in northern high latitude watersheds influenced by permafrost. Total dissolved (<0.45mm) concentrations and the 'nanocolloidal size distributions' (0.5-40 nm) of UV-absorbing dissolved organic matter, Fe, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu were determined by on-line coupling of flow field-flow fractionation (FFF) with a UV-absorbance detector and ICP-MS. Total dissolved and nanocolloidal concentrations of the REEs co-varied with dissolved organic carbon (DOC) in all rivers and between spring flood and late summer baseflow. The nanocolloidal size distributions indicated the presence of three major components of nanocolloids: the 0.5-3 nm 'fulvic-rich nanocolloids' occurring throughout the sampling season, the 'organic/iron-rich nanocolloids' residing in the <8 nm size range during the spring flood, and the 4-40 nm iron-rich nanocolloids occurring during summer baseflow. REEs associated with all the three components of nanocolloids, but the proportions associated with the fulvic-rich nanocolloids during summer baseflow increased with increasing REE molar mass, which is consistent with the increase in stability of organic REE-complexes with increasing REE molar mass. Normalization of the measured REE-concentrations with the average REE-concentrations of the upper continental crust revealed a dynamic change in the physicochemical fractionation of REEs. During the spring flood, REE-binding in all the rivers was dominated by the <8 nm organic/iron-rich nanocolloids, likely being eroded from the upper organic-rich soil horizon by the strong surface runoff of snowmelt water. During the summer, the REE-binding in rivers with large groundwater input was dominated by small (<0.5 nm) organic and/or inorganic complexes, while lower proportions of the REEs were associated with both the 0.5-3 nm fulvic rich and 4-40 nm iron rich nanocolloids and with larger >40 nm colloids. In a river sampled at higher altitude, the <8 nm organic/iron-rich and 4-40 nm iron-rich nanocolloids dominated the REE-binding also during the summer, which could be a result of persistent permafrost confining water flows to the upper organic-rich soil horizons. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.gca.2012.12.033
13055342 Helbig, Manuel (University of Hamburg, Institute of Soil Science, Hamburg, Germany); Boike, Julia; Langer, Moritz; Schreiber, Peter; Runkle, Benjamin R. K. and Kutzbach, Lars. Spatial and seasonal variability of polygonal tundra water balance; Lena River Delta, northern Siberia (Russia): in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 133-147, illus. incl. 1 table, sketch map, 65 ref., February 2013.
The summer water balance of a typical Siberian polygonal tundra catchment is investigated in order to identify the spatial and temporal dynamics of its main hydrological processes. The results show that, besides precipitation and evapotranspiration, lateral flow considerably influences the site-specific hydrological conditions. The prominent microtopography of the polygonal tundra strongly controls lateral flow and storage behaviour of the investigated catchment. Intact rims of low-centred polygons build hydrological barriers, which release storage water later in summer than polygons with degraded rims and troughs above degraded ice wedges. The barrier function of rims is strongly controlled by soil thaw, which opens new subsurface flow paths and increases subsurface hydrological connectivity. Therefore, soil thaw dynamics determine the magnitude and timing of subsurface outflow and the redistribution of storage within the catchment. Hydraulic conductivities in the elevated polygonal rims sharply decrease with the transition from organic to mineral layers. This interface causes a rapid shallow subsurface drainage of rainwater towards the depressed polygon centres and troughs. The re-release of storage water from the centres through deeper and less conductive layers helps maintain a high water table in the surface drainage network of troughs throughout the summer. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0933-4
13055332 Hinzman, Larry D. (University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK); Destouni, Georgia and Woo, Ming-ko. Hydrogeology of cold regions: Hydrogeology Journal, 21(1), 316 p., illus., February 2013. Individual papers are cited separately.
13057428 Li Ruiping (Inner Mongolia Agricultural University, College of Water Conservancy and Civil Engineering, Hohhot, China); Shi Haibin; Flerchinger, G. N.; Zou Chunxia and Li Zhengzhong. Modeling the effect of antecedent soil water storage on water and heat status in seasonally freezing and thawing agricultural soils: Geoderma, 206, p. 70-74, illus. incl. 1 table, sketch map, 28 ref., September 2013.
Taking the Inner Mongolia Hetao Irrigation District (IMHID) agricultural production region as a background and based on field data and local meteorological data, the influence of antecedent soil water storage (ASWS) on water and heat status was simulated and analyzed using the SHAW model during the seasonal freezing-thawing period. The results showed that the amount of ASWS prior to soil freezing can influence the depth of freezing and penetration of low temperatures. When ASWS within the surface 1 m is less than or equal to 150 mm, soil water storage (SWS) was always increasing over the winter period. However, for ASWS greater than 150 mm, SWS went through 3 phases: at first it decreased, later it increased, and eventually it decreased again. During soil freezing, the amount of upward water transfer made up the deficit caused by evaporation and percolation for ASWS less than or equal to 150 mm. Conversely, the amount of percolation was greater than that of upward transfer for ASWS greater than 150 mm. During soil thawing, water continued to transfer from lower soil layers to upper layers and overtook evaporation and percolation for ASWS less than or equal to 210 mm. However, the amount of evaporation and percolation was greater than the upward transfer for ASWS larger 210 mm. These results may be used to assist in appropriate irrigation scheme in autumn, agricultural irrigation water management and research on reducing soil secondary salinization. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.geoderma.2013.04.021
13055577 Garbout, Amin (University of Nottingham, Division of Agricultural and Environmental Sciences, Nottingham, United Kingdom); Munkholm, Lars J. and Hansen, Soren B. Temporal dynamics for soil aggregates determined using X-ray CT scanning: Geoderma, 204-205, p. 15-22, illus. incl. 3 tables, 33 ref., August 2013.
Soil structure plays a key role in the ability of soil to fulfil essential soil functions and services in relation to e.g. root growth, gas and water transport and organic matter turnover. However, soils are not a very easy object to study as they are highly complex and opaque to the human eye. Traditionally, they have been studied using invasive or destructive techniques. The advantage of using X-ray computed tomography (CT) in soil morphology is that it enables non-destructive quantification of soil structure in three dimensions (3D). The prime objective of the present study was to characterize soil aggregate properties such as volume, surface area and sphericity based on 3D images. We tested the methods on aggregates from different treatments and quantified changes over time. A total of 32 collections of aggregates, enclosed in mesocosms, were incubated in soil to follow the structural changes over time for different treatments. The aggregates had different origins (tillage and no-till), and the mesocosms were incubated in soil grown with and without plants. The aggregates were not segmented into single aggregates, but considered as an aggregate cluster. To describe the aggregate cluster shape changes, several morphometric parameters were quantified such as aggregate cluster volume, sphericity, and the number of inter-aggregate pores. These parameters were measured from 3D images produced non-destructively by an X-ray CT scanner at three different times: (a) the initial state before incubation, (b) after summer incubation, and (c) after summer and winter incubation. The macroporosity of the aggregate clusters decreased after incubating the samples during summer and during summer and winter. The plant treatment curbed the decrease in porosity over time. The volume and surface area of the aggregate clusters increased with time irrespective of tillage and plant treatments. The sphericity decreased with time. The structure model index (SMI) was not sensitive to effects of time and treatments. This means that with time the aggregate clusters became less round and more elongated, but they kept a rough surface. The 3D CT scanner image analysis based on quantification of morphometric parameters has the potential to provide new fundamental insight into soil aggregate formation and the effect of different treatments despite the limitations of its spatial resolution. In our study, time was the most important factor affecting the changes in aggregate shape and structure. Contrary to what we had expected, there was no significant effect of seven years of different tillage treatments on the measured parameters at any time of measurement. The segmentation method used to separate aggregate from air is of primary importance, particularly when it comes to the quantification of aggregate morphometric parameters. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.geoderma.2013.04.004
13057451 Garcia-Guinea, Javier (Museo Nacional de Ciencias Naturales, Madrid, Spain); Recio-Vazquez, Lorena; Almendros, Gonzalo; Benavente, David; Correcher, Virgilio; Perez-Garcia, Antonio; Sanchez-Moral, Sergio and Fernandez-Cortes, Angel. Petrophysical properties, composition and deterioration of the Calatorao biogenic stone; case of the sculptures masonry of the Valley of the Fallen (Madrid, Spain): Environmental Earth Sciences, 69(5), p. 1733-1750, illus. incl. strat. col., 3 tables, sketch map, 49 ref., July 2013.
The huge sculptures placed outdoors in the Valley of the Fallen Memorial Park (El Escorial, Madrid) made with blocks of Black-Limestone from Calatorao-Zaragoza, Spain (BLCZ) and disposed on a concrete core exhibit weathering traces, flaking, saline efflorescence and falling fragments, currently represent a danger for visitors. Frost action is important in the Valley of the Fallen by the large number of freeze-thaw cycles produced during Sculptures'live under a temperate Mediterranean climate with severe seasonality. The formation of fissures facilitates the water transport within the rock and the salt- and ice-induced deterioration. Temperate climates with frequent freezing and thawing cycles can be the most effective drivers of the visible physical weathering. In order to propose a suitable weathering model, collected black-limestones from sculptures and Calatorao quarries were analyzed by optical microscopy, environmental scanning electron microscopy with energy dispersive spectrometry (ESEM-EDS), inductively coupled mass spectrometry (ICP-MS) and X-ray diffraction. Mercury intrusion porosimetry (MIP), nitrogen absorption and helium pycnometry techniques were used for pore analyses of the BLCZ micro-blocks (10 ´ 10 ´ 10 cm) described in terms of pore size distribution, pore volume and specific surface area. The appreciable amount of organic matter was isolated by solvent extraction, acid treatment, flotation and perborate degradation followed by Gas Chromatography-Mass Spectrometry (GC-MS), Analytical Pyrolysis (Py-GC/MS), Fourier Transformed Infrared Spectroscopy and Raman techniques. Both weathered and fresh BLCZ samples contained more than 90 % calcite shells with circa 10 % of pyrite (fresh samples) or iron hydroxides (weathered samples), quartz grains, claystone and fossil organic matter consisting of a condensed matrix with polyalkyl chains and polycyclic methoxyl-lacking aromatic structures. The petrophysical analyses revealed volumes of pores, sized <0.025 mm obtained by N2 adsorption, of 3.18 ´ 10-3 cm3 g-1 while the measured porosity by MIP in the pore range from 0.005 to 200 mm was 3.30 ´ 10-3 cm3 g-1. These data could be explained by the existence of clay minerals and organic matter in the pore system less than 50 nm of diameter. Concerning BLCZ deterioration it was found that the porous framework of BLCZ was filled with sulphates formed from artificial cement observed in the sculptures inside trough a testing hole and from its intrinsic pyrite. The results suggested that although biological processes were not major agents in rock deterioration, there was also weak compatibility between sculptures' constituents, (limestone, concrete and oxidized iron clamps) which under, continental Mediterranean conditions, were continuously releasing weathering compounds accelerating disruption of the cut-stone sculptures. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s12665-012-2007-2
13054269 Levy, Joseph S. (Oregon State University, College of Earth, Ocean and Atmospheric Sciences, Corvallis, OR); Fountain, Andrew G.; O'Connor, Jim E.; Welch, Kathy A. and Lyons, W. Berry. Garwood Valley, Antarctica; a new record of last glacial maximum to Holocene glaciofluvial processes in the McMurdo dry valleys: Geological Society of America Bulletin, Pre-Issue Publication, illus. incl. sects., 6 tables, sketch map, 42 ref., June 7, 2013.
We document the age and extent of late Quaternary glaciofluvial processes in Garwood Valley, McMurdo Dry Valleys, Antarctica, using mapping, stratigraphy, geochronology, and geochemical analysis of sedimentary and ice deposits. Geomorphic and stratigraphic evidence indicates damming of the valley at its Ross Sea outlet by the expanded Ross Sea ice sheet during the Last Glacial Maximum. Damming resulted in development of a proglacial lake in Garwood Valley that persisted from late Pleistocene to mid-Holocene time, and in the formation of a multilevel delta complex that overlies intact, supraglacial till and buried glacier ice detached from the Ross Sea ice sheet. Radiocarbon dating of delta deposits and inferred relationships between paleolake level and Ross Sea ice sheet grounding line positions indicate that the Ross Sea ice sheet advanced north of Garwood Valley at ca. 21.5 ka and retreated south of the valley between 7.3 and 5.5 ka. Buried ice remaining in Garwood Valley has a similar geochemical fingerprint to grounded Ross Sea ice sheet material elsewhere in the southern Dry Valleys. The sedimentary sequence in Garwood Valley preserves evidence of glaciofluvial interactions and climate-driven hydrological activity from the end of the Pleistocene through the mid-Holocene, making it an unusually complete record of climate activity and paleoenvironmental conditions from the terrestrial Antarctic.
DOI: 10.1130/B30783.1
13053770 Toner, Jonathan D. (University of Washington, Department of Earth and Space Sciences, Seattle, WA) and Sletten, Ronald S. The formation of Ca-Cl-rich ground waters in the Dry Valleys of Antarctica; field measurements and modeling of reactive transport: Geochimica et Cosmochimica Acta, 110, p. 84-105, illus. incl. 10 tables, sketch map, 60 ref., June 1, 2013. Includes appendices.
Ca-Cl-rich brines have been found in shallow subsurface flows, groundwater systems, lakes, and ponds throughout the Dry Valleys of Antarctica. The apparent abundance of Ca-Cl-rich waters near the surface is unusual compared to global surface water compositions and a number of theories have been proposed to explain the genesis of these brines. We show that an ice-cemented soil developing on fluvial sediment in Taylor Valley also contains Ca-Cl-rich brine. The distribution of soluble ions, exchangeable cations, and stable isotopes down to 2.1 m depth in the soil suggests that CaCl2 was formed by cation exchange reactions during downward reactive transport of Na-Cl-rich brine from the soil surface. To explore the implications of exchange reactions for the formation of Ca-Cl-rich brine, Ca-Na and Ca-Mg exchange properties were measured in 1 mM, 0.1 M, and 4.75 M solutions. Low-temperature reactions and brine transport were modeled in PHREEQC by incorporating FREZCHEM Pitzer parameters and solubility products into PHREEQC. Modeling shows that by freezing soils in equilibrium with Dry Valley surface waters, a strong Ca-Mg enrichment of the soil solution is caused by the exchange of aqueous Na+ with exchangeable Ca2+ and Mg2+. Ca-Mg enrichment also occurs as Na-Cl-rich brine from the soil surface advects into ice-cemented soil. By modeling this process in the borehole soil, trends in ion distributions with depth can be predicted. Brine compositions from cation exchange reactions are consistent with Ca-Cl-rich brine compositions in the Dry Valleys, although additional water-rock interaction is proposed to account for the low Mg2+ concentrations in Don Juan Pond. Furthermore, the amount of CaCl2 that can be produced by exchange reactions is consistent with estimated amounts of CaCl2 in groundwaters beneath Don Juan Pond. This suggests that cation exchange reactions can explain the Ca-Cl-rich composition of the enigmatic Don Juan Pond and other brines in the Dry Valleys. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.gca.2013.02.013
13054040 Marke, T. (University Innsbruck, Institute of Geography, Innsbruck, Austria); Strasser, U.; Kraller, G.; Warscher, M.; Kunstmann, H.; Franz, H. and Vogel, M. The Berchtesgaden National Park (Bavaria, Germany); a platform for interdisciplinary catchment research: in WESS; an interdisciplinary research in catchments (Kolditz, Olaf; et al.), Environmental Earth Sciences, 69(2), p. 679-694, illus. incl. 1 table, 65 ref., May 2013.
The Berchtesgaden National Park (Bavaria, Germany), a study site of the UNESCO Man and the Biosphere program in the catchment of Berchtesgadener Ache, is introduced as a platform for interdisciplinary research. As the investigation of how human activities affect the natural resources in the park area, which has been defined a main aim of the program, naturally requires expertise from different scientific fields, interdisciplinary research has been fostered in the national park plan since the very beginning of the Man and the Biosphere program in 1981. To analyze the complex interactions and mutual dependencies between socio-economic and natural systems, a variety of monitoring programs have been initialized in different disciplines (e.g. climate sciences, zoology, botany) that are addressed in this paper. As a result of these research efforts, the park offers a profound data basis to be used in future studies (e.g. land cover classifications, maps of geological and soil conditions). Detailed information is provided on a climate monitoring network that has been installed in the park starting in the year 1993. The network has been continuously extended over the years and now provides extraordinary comprehensive information on meteorological conditions in the park, setting the basis for current as well as for potential future climate-related studies. A special characteristic of the station network is the fact that it covers a large range of elevations from 600 m a.s.l in the valleys to 2,600 m a.s.l in the summit regions and is therefore able to capture altitudinal gradients in meteorological variables as typical for Alpine regions. Due to the large number of stations in high elevations (15 stations are in elevations higher than 1,500 m a.s.l) the network provides information on the complex hydrometeorological conditions in summit regions which are often insufficiently represented in observation networks due to the increased costs for maintenance of climate stations in these locations. Beside the various monitoring programs, a variety of numerical models have been (further) developed for application in the park area that make extensive use of the different data collected and therefore largely benefit from the comprehensive data pool. The potential and necessity of the climate monitoring network for modelling studies is demonstrated by utilizing the meteorological recordings in the framework of a hydrometeorological simulation experiment. Further examples of environmental modelling efforts are shortly described together with preliminary model results. Copyright 2013 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s12665-013-2317-z
13053965 Chase, Ronald B. (Western Michigan University, Department of Geosciences, Kalamazoo, MI) and Selegean, James P. Geology, erosion history, and mitigation strategies applied to Great Lakes coastal bluffs; an examination of the Allegan County, Michigan, dewatering demonstration site: in Insights into the Michigan Basin; salt deposits, impact structure, youngest basin bedrock, glacial geomorphology, dune complexes, and coastal bluff stability (Gillespie, Robb, editor), GSA Field Guide, 31, p. 103-118, illus. incl. sects., strat. cols., sketch maps, 23 ref., April 2013.
The Great Lakes coast contains numerous unstable bluffs underlain by heterogeneous glacial materials consisting of till, sand, and gravel layers, and lacustrine clays. Many of the bluffs are steeper than their equilibrium angles and typically move as slow earth slides or occasional rapid slumps. Such movements develop largely where interlayered sand and clay contain perched groundwater that acts to reduce effective stress during winter months when perched potentiometric surface elevations rise because water cannot discharge through frozen soil. Aerial photograph records dating back to 1938 show that bluffs recede in amphitheater-like depressions followed by "catch up" where headlands between amphitheaters are attacked by other forms of erosion. This bluff recession is particularly pronounced during stages of high lake levels. The erosion control experiment described herein has been designed to determine the manner in which groundwater activity influences the causes and mechanisms of mass wasting on the Great Lakes coasts. Three dewatering demonstration sites were selected, monitored electronically for virtually all movement and cause relationships, and dewatered to demonstrate a potential mitigation strategy other than construction of wave barriers. Erosion activity and dewatering effects were carefully monitored for three seasonal cycles. Results show that (1) dewatering greatly reduces ground displacements during winter months, and (2) bluff movements are almost perfectly timed to, or lag slightly after, the hours when potentiometric surfaces near the bluff face reach their highest elevations during freezing (greatest soil pore pressure) or their greatest rates of surficial discharge (soon after thaw).
DOI: 10.1130/2013.0031(06)
13053679 Hao Fanghua (Beijing Normal University, School of Environment, Beijing, China); Chen Siyang; Ouyang Wei; Shan Yushu and Qi Shasha. Temporal rainfall patterns with water partitioning impacts on maize yield in a freeze-thaw zone: Journal of Hydrology, 486, p. 412-419, illus. incl. 9 tables, sketch map, 50 ref., April 12, 2013.
Understanding all components of the water balance, especially temporal rainfall patterns, is essential to optimize water use in rain-fed agriculture area. The effect of temporal rainfall patterns on water balance, evapotranspiration (ET), and crop growth was evaluated by considering root water extraction of plants in a rain-fed maize field. Soil water contents at depths of 15, 30, 60, and 90 cm were measured daily in 2-year growth seasons. A soil water balance approach was applied to estimate changes in daily soil water storage. For the detailed water partitioning of the water balance and root water extraction, the soil-water-atmosphere-plant (SWAP) model with water and crop modules was applied. Results suggested that the main depths of root water uptake occurred in the top 60 cm soil layer. Crop transpiration (T) can reach a level above 40% of the total water consumption during all growth stages, and its reduction was mainly due to the dry condition of soil. The crop yield in 2010 was 1125 kg ha-1 higher than that in 2011, although the rainfall amount in that year was 132 mm less than the rainfall amount in 2011. The water use efficiency (WUE) was also higher in 2010. Therefore, the influence of temporal rainfall patterns was clearly more important than rainfall amounts (water partitioning into evaporation (E), T, and soil water content). Growing season T/ET can be a potential parameter for maize productivity. The field can be irrigated at pivotal growth stages under dry conditions to obtain the optimal effect in improving WUE and increasing grain yield. The SWAP model was a useful tool to analyze water partitioning in the freeze-thaw zone. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.jhydrol.2013.02.008
13053622 Nystrand, Miriam I. (Abo Akademi University, Geology and Mineralogy, Abo, Finland) and Osterholm, Peter. Metal species in a boreal river system affected by acid sulfate soils: Applied Geochemistry, 31, p. 133-141, illus. incl. 1 table, sketch map, 135 ref., April 2013. Includes appendices.
The bioavailability of metals and their potential for environmental pollution depends not simply on total concentrations but on their chemical form. Consequently, knowledge of aqueous metal speciation is essential in investigating potential metal toxicity and mobility. Dissolved (<1kDa), colloidal (1kDa-0.45mm) and particulate (>0.45mm) size fractions of sulfate, organic C (OC) and 18 metals/metalloids were investigated in the extremely acidic Vora River system in Western Finland, which is strongly affected by acid sulfate (AS) soils. In addition, geochemical modelling was used to predict the formation of free ions and complexes in these acidic waters. The most important finding of this study is that the very large amounts of elements known to be released from AS soils (including Al, Ca, Cd, Co, Cu, Mg, Mn, Na, Ni, Si and U) occur and can prevail mainly in toxic forms throughout acidic river systems; as free ions and/or sulfate-complexes. This has serious effects on the biota and particularly dissolved Al can be expected to have acute effects on fish and other organisms. In the study area, only the relatively forested upstream area (higher pH and contents of OC) had significant amounts of a few bioavailable elements (including Al, Cu, Ni and U) due to complexation with the more abundantly occurring colloidal OC in the upstream area. It is, however, notable that some of the colloidal/particulate metals were most likely associated with metal bearing phyllosilicates eroded from clay soils. Moreover, the mobilisation of Fe and As was small and As was predicted to be associated with Fe oxides, indicating a considerable influence of Fe oxides on the mobilisation/immobilisation processes of As. Elements will ultimately be precipitated in the recipient estuary, where the acidic metal-rich river water will gradually be diluted/neutralised with brackish seawater in the Gulf of Bothnia. According to speciation modelling, such a pH rise may first cause precipitation of Al, Cu and U together with organic matters closest to the river mouth, in line with previous sediment studies from the estuary. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.apgeochem.2012.12.015
13053554 Sjostedt, Carin (Royal Institute of Technology, Department of Land and Water Resources Engineering, Stockholm, Sweden); Persson, Ingmar; Hesterberg, Dean; Kleja, Dan Berggren; Borg, Hans and Gustafsson, Jon Petter. Iron speciation in soft water lakes and soils as determined by EXAFS spectroscopy and geochemical modelling: Geochimica et Cosmochimica Acta, 105, p. 172-186, illus. incl. 4 tables, 48 ref., March 15, 2013. Includes appendices.
Complexation of iron by organic matter can potentially compete with toxic metals for binding sites. Iron(III) forms both monomeric and di/trimeric complexes with fulvic and humic acids, but the nature and extent of complexation with natural organic matter samples from soft-water lakes has not been extensively studied. The aim of this study was to determine the coordination of iron in complexes with organic matter in two soft-water lakes and in the surrounding Oe soil horizons. Iron K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy was performed on particles and large colloids (>0.45mm) collected by in-line pre-filtration, and on smaller colloids isolated both on an AGMP-1 anion-exchange column and by concentration using 1000Da ultrafiltration. The results showed that iron(III) was mainly present in monomeric complexes with organic matter, both in the lake water smaller colloids and in the soil samples. Evidence for iron(III) (hydr)oxides was found for the lake particles, in the ultrafiltration retentates, and in some of the soils. Overall, the results suggest that complexation of iron(III) to organic matter prevents hydrolysis into polymeric forms. Strong complexation of iron(III) would lead to competition with other metals for organic-matter binding sites. Abstract Copyright (2013) Elsevier, B.V.
DOI: 10.1016/j.gca.2012.11.035
13055336 Ireson, Andrew M. (University of Saskatchewan, Global Water Security Institute, Saskatoon, SK, Canada); van der Kamp, G.; Ferguson, G.; Nachshon, U. and Wheater, H. S. Hydrogeological processes in seasonally frozen northern latitudes; understanding, gaps and challenges: in Hydrogeology of cold regions (Hinzman, Larry D.; et al.), Hydrogeology Journal, 21(1), p. 53-66, illus., 91 ref., February 2013.
The groundwater regime in seasonally frozen regions of the world exhibits distinct behavior. This paper presents an overview of flow and associated heat and solute transport processes in the subsurface, from the soil/vadose zone, through groundwater recharge to groundwater discharge processes in these areas. Theoretical developments, field studies and model development are considered. An illustrative conceptual model of the system is presented. From a groundwater perspective, the dominant effect is the extent of hydraulic isolation between the water above and that below the near-surface frozen zone. The spatial and temporal occurrences of this isolation are seasonally variable and may also be modified under a future changing climate. A good qualitative conceptual understanding of the system has been developed over numerous decades of study. A major gap is the inability to effectively monitor processes in the field, particularly unfrozen water content during freezing conditions. Modeling of field-scale behavior represents a major challenge, even while physically based models continue to improve. It is suggested that progress can be made by combining well-designed field experiments with modeling studies. A major motivation for improving quantification of these processes derives from the need to better predict the impacts of a future changing climate. Copyright 2012 Springer-Verlag Berlin Heidelberg
DOI: 10.1007/s10040-012-0916-5
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