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Ramsdale, Jason. "Studies of glacial and periglacial environments on Mars." Thesis, Open University, 2017. http://oro.open.ac.uk/49751/.
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This thesis presents the development and application of a grid-based mapping approach that provides an efficient solution to the problems of mapping small landforms over large areas. The approach allows the cataloguing of landform classes, of multiple sizes, efficiently in a single pass. The speed at which the data could be recorded allowed for the first continuous, full resolution mapping of decametre-scale landforms in CTX images on hemispherical-scale maps. The discrete, tabular nature of grid mapping opens up the possibility of citizen science meaning the grid mapping approach could have considerable future use and impact. The main scientific goal of this thesis was to determine the distribution and origins of ice-related landforms in the northern plains, and provide insight as to whether these landforms are related to distinct geological or geomorphological units. To accomplish this, I used the grid mapping approach to explore a large tract covering the Arcadia Planitia region of the northern plains of Mars. In addition, I was able to compare these results to two other sister studies performed in the Utopia and Acidalia Planitia regions of Mars. To explore possible sources of ice I performed a detailed study of the Rahway Vallis system. This found an assemblage of terraces, channels and sinuous ridges in Rahway Vallis that are topographically and morphologically consistent with either a draining lake, or a melting, once liquid, ice-body, and is indicative of a flow of volatiles into the northern plains and large scale shifts in ground ice stability. Overall, this thesis demonstrates the dominant effects of the deposition and sublimation of the Latitude Dependent Mantle in shaping recent landscapes on the northern plains of Mars. There was little evidence for thaw-related landforms, and evidence for a fluvial origin for ice in the near surface is circumstantial, or has been erased or covered.
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Miller, Helen. "Lake bed environments, modern sedimentation and the glacial and post-glacial history of Windermere, UK." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/365472/.
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Windermere, the largest natural lake in England, is a glacial ribbon lake located in the southeast of the Lake District. High resolution geophysical datasets, combined with sediment analysis, geomorphological mapping and historical research have been used to investigate the lake bed environments, recent sediment record of pollution and glacial and post-glacial history of the lake and surrounding catchment. The data are used to generate a present-day landscape map of Windermere, revealing a complex landform record characterised by nine sub-basins, separated by steps, ridges and isolated topographic highs related to the retreat of the British and Irish Ice Sheet (BIIS). Debris flows and anthropogenic features are superimposed on the general bathymetric framework formed since the Last Glacial Maximum. Analysis of sediment cores and correlation with existing seismic data have revealed key stratigraphic facies extend across the lake basin, and consist of a drape of Holocene gyttja overlying glaciolacustrine and lacustrine sediment fill relating to retreat of the BIIS. Analysis of geophysical core properties have identified a peak in magnetic susceptibility and iron which possibly represents a change in relative input from different ice masses. Onshore mapping of Troutbeck Valley identifies a series of depositional environments, including recessional moraines formed by still-stands or small readvances of an outlet glacier. Following deglaciation through disintegration into a number of independent ice caps, major sediment redistribution led to formation of a large fan delta via paraglacial and post-glacial sedimentation. The sedimentology of Windermere is characterised by five distinct lake bed facies showing a dominance of gyttja, representing recent Holocene sedimentation derived from the catchment over the last 10,000 years. Coarser sediments (gravel and fine sand) are found in lake-marginal shallow water. High resolution geochemical data, radiochronology and isotopic analysis have revealed significant increases in lead, zinc and copper in recent lake sediments. The principal sources of anthropogenic lead contamination are gasoline lead, Carboniferous coal (most likely source is coal fired steam ships) and lead derived from Carboniferous Pb-Zn mineralisation (mining activities). A number of up-system sediment traps have limited the amount of mining related heavy metals entering Windermere. As a result, many peaks in heavy metals do not correlate with periods of metal workings, but recent increases are possibly due to flood-induced metal inwash. Elevated concentrations of zinc and filamentous growths on the lake bed are attributed to sewage inputs. Geophysical, physical and visual surveys of twelve demonstrated or putative spawning grounds of Arctic charr (Salvelinus alpinus) suggest suitable spawning habitat in Windermere is limited and siltation by fine sediments has occurred over the past 50 years. The integrated approach used in this study has shown that a catchment analysis, using several datasets and techniques, can be used to inform wider regional and ice sheet wide glacial reconstructions. This approach, which can be applied to other lacustrine environments, is capable of determining modern lake bed habitats and the sediment record of pollution, and further demonstrates the value of lake sediments as a high resolution record of local and regional environmental change.
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Brown, Giles Hartley. "Solute provenance and transport pathways in Alpine glacial environments." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303070.
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Williams, Stephen Vincent. "Visual arctic navigation: techniques for autonomous agents in glacial environments." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41135.
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Arctic regions are thought to be more sensitive to climate change fluctuations, making weather data from these regions more valuable for climate modeling. Scientists have expressed an interest in deploying a robotic sensor network in these areas, minimizing the exposure of human researchers to the harsh environment, while allowing dense, targeted data collection to commence. For any such robotic system to be successful, a certain set of base navigational functionality must be developed. Further, these navigational algorithms must rely on the types of low-cost sensors that would be viable for use in a multi-agent system. A set of vision-based processing techniques have been proposed, which augment current robotic technologies for use in glacial terrains. Specifically, algorithms for estimating terrain traversability, robot localization, and terrain reconstruction have been developed which use data collected exclusively from a single camera and other low-cost robotic sensors. For traversability assessment, a custom algorithm was developed that uses local scale surface texture to estimate the terrain slope. Additionally, a horizon line estimation system has been proposed that is capable of coping with low-contrast, ambiguous horizons. For localization, a monocular simultaneous localization and mapping (SLAM) filter has been fused with consumer-grade GPS measurements to produce full robot pose estimates that do not drift over long traverses. Finally, a terrain reconstruction methodology has been proposed that uses a Gaussian process framework to incorporate sparse SLAM landmarks with dense slope estimates to produce a single, consistent terrain model. These algorithms have been tested within a custom glacial terrain computer simulation and against multiple data sets acquired during glacial field trials. The results of these tests indicate that vision is a viable sensing modality for autonomous glacial robotics, despite the obvious challenges presented by low-contrast glacial scenery. The findings of this work are discussed within the context of the larger arctic sensor network project, and a direction for future work is recommended.
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Veerapaneni, Ram S. "Analysis and Characterization of Microbes from Ancient Glacial Ice." Bowling Green State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1256565133.
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Dix, Justin K. "The use of high resolution geophysics for the investigation of submerged palaeo-glaciomarine environments." Thesis, University of St Andrews, 1996. http://hdl.handle.net/10023/15271.
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A multi-disciplinary, high resolution, geophysical investigation of a Scottish Sea loch has facilitated both the reconstruction of a detailed late Quaternary para-stratigraphic model and the critical assessment of the acquisition and analytical methodologies most appropriate for the study of submerged palaeo-glaciomarine environments. Loch Ainort, situated on the eastern coast of the Isle of Skye, has been surveyed using a 192 kHz echosounder, a 400 kHz side scan sonar and a 3.5 kHz sub-bottom profiler. Lithological calibration was provided by the analysis of both in situ core data and extant terrestrial data sets. It is proposed that for the effective reconstruction of these and any other nearshore palaeo-environments a multi-disciplinary geophysical approach is essential. The critical control on success is the adherence, during interpretation, to a single unifying seismo-analytical framework. The seismo-stratigraphical analysis technique has been adapted for high- resolution work in order to provide this rigid framework. Objective descriptive analysis of the seismic traces provides a "seismic para-stratigraphy" which when combined with lithological data is used to construct a "composite para-stratigraphy". This is a process based, litho-stratigraphic interpretation that, by virtue of the detailed spatial extent afforded it by geophysical data, can be placed in a wider environmental context. The composite para-stratigraphy for the Loch Ainort basin is dominated by Loch Lomond Stadial glacial activity. Terminal and readvance limits are identified at several localities within the basin. Variable morphological styles of the glacial sequences show that deglaciation occurred in two distinct, climatically controlled, phases. The first marked by a fluctuating ice margin and the second by uninterrupted retreat and in situ ice stagnation. Sub-aerially induced debris flows occur during the initial paraglacial phase but stabilisation of exposed slopes restricts this input and rapid sedimentation of fines from sediment-rich meltwaters becomes dominant. Modern fjordic sedimentation develops after the disappearance of glacier ice.
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Francis, Elizabeth. "The palynology of the Glencloy area." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317068.
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Fleming, Edward James. "Magnetic, structural and sedimentological analysis of glacial sediments : insights from modern, Quaternary and neoproterozoic environments." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4883/.
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Glacial sediments, particularly diamicts, can be ambiguous to interpret. Fabric analyses, such as anisotropy of magnetic susceptibility (AMS), have been shown to provide specific information on the formation and subsequent deformation of glacial sediments. In this thesis, detailed investigations utilising the AMS technique have been combined with traditional sedimentological and structural techniques, to help resolve a number of current problems in glacial geology. At the same time, limitations of such uses of AMS have been established. In the modern environment (Tunabreen, Svalbard), magnetic lineations develop parallel to glacier flow and reveal dynamic behaviour during past surges. In a Quaternary glaciotectonite (Bacton Green Till Member, Norfolk, UK), AMS fabric develop in response to glacial deformation and reveal strain vectors that can be related to ice flow from contrasting directions. Finally in Neoproterozoic diamictites (Wilsonbreen Formation, Svalbard), despite local tectonic overprinting and diagenetic change, AMS can be used to reveal a dominant ice-flow to direction to the north. In combination with other sedimentological techniques, this has allowed the identification of glaciotectonic features and an ice-marginal, terrestrial and subaqueous model is proposed. These results support the use of AMS as a fast, objective and accurate technique that can facilitate the interpretation of cryptic glacial sediments.
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Bruckner, Monica Zanzola. "Biogeochemistry and hydrology of three alpine proglacial environments resulting from glacier retreat." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/bruckner/BrucknerM1208.pdf.
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Proglacial environments, formed by glacier retreat, exhibit distinct characteristics in discharge, water temperature, water residence time, and dissolved ion, carbon, and suspended sediment concentrations. The unnamed alpine glacier at the headwaters of the Wheaton River, Yukon, Canada, provides an ideal setting to compare deglaciation processes that result in three different proglacial environments. The glacier has evolved from occupying one large catchment (~4 km 2) to two smaller catchments (each ~2 km 2) via glacier thinning and net mass loss, forming two lobes separated by a medial moraine. Field observations revealed neither crevasses nor evidence of subglacial drainage outlets and suggested this glacier had a non-temperate thermal regime with meltwater predominantly flowing from supraglacial and ice marginal sources. Climate and bedrock geology were similar for the subcatchments, providing a natural laboratory to compare deglaciation processes. This study compared the hydrology and biogeochemistry of three outlet streams from this glacier: one stream drained a proglacial lake which is fed by meltwater from the lower west lobe, a second stream drained the upper west lobe, and a third stream was the major drainage outlet for the east lobe. Hydrologic monitoring over the 2006 melt season (June-August) and analyses of water samples for dissolved ion content and carbon indicated that the meltwaters are dominated by Ca 2+ and HCO 3-, which are derived from biogeochemical weathering of crustal materials. The study demonstrated that the presence of the proglacial lake, which acted as a meltwater reservoir, measurably modified meltwater residence time, water temperature, water chemistry, and bacterial biomass relative to the proglacial streams. Rock:water interaction between meltwater and medial morainal sediment and fine-grained, reactive glacial flour suspended in the streams and the lake water column also enhanced biogeochemical weathering within the catchment. Thus, this study provided a small-scale example for how differences in proglacial environments and water flow paths affect headwater hydrology and biogeochemistry. This study was the first of its kind in the Coast Mountains, Yukon, Canada, and results presented here aid in the understanding of how proglacial environments created by climate-induced glacier retreat affect hydrochemistry, hydrology, and carbon dynamics in remote high elevation environments.
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Stevenson, Emily Isabel. "Stable strontium isotope fractionation in marine and terrestrial environments." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:a2d97fc7-3e9d-484a-8026-11c118fcc3fd.
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The work reported in this thesis applies a new isotope tracer, stable strontium isotopes (δ88/86Sr), to address questions concerning changes in global climate that occur in response to continental weathering processes, and to constrain the modern marine geochemical Sr cycle. Stable Sr isotopes are a relatively new geochemical proxy, and as such their behavior needs to be understood in differing forms of marine calcium carbonate, the archives from which records of past stable Sr variability in the oceans can be constructed. Foraminifera, coccoliths and corals (both aragonite and high Mg calcite) acquire δ88/86Sr values lighter than that of modern day seawater, (approximately 0.11, 0.05, 0.2 and 0.19 ‰ lighter than seawater at ~25°C respectively) providing a measureable offset which can be used to constrain the modern Sr outputs from the ocean and provide a better understanding of the modern Sr cycle. Using foraminifera as a sedimentary archive the first marine δ88/86Sr record of seawater over the last two glacial cycles has been constructed, and used to investigate changing carbonate input and output over this 145 kyr period. Modelling of the large excursion of δ88/86Sr to heavier values during Marine Isotope Stage (MIS) 3, reveals that this is more likely to be due to local changes in seawater or post-depositional alteration, rather then whole ocean changes. In the terrestrial environment δδ88/86Sr has been measured in the dissolved load of rivers from the Himalaya. It is found that, in general, rivers draining carbonate catchments possess lighter isotopic δ88/86Sr values than those from rivers draining silicates. Covariations of either δ88/86Sr vs. δ30Si or δ88/86Sr vs. 1/[Sr] can be used to distinguish between rivers draining different catchment areas.
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Kikuchi, Colin. "Spatially Telescoping Measurements for Characterization of Ground Water - Surface Water Interactions along Lucile Creek, Alaska." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/202976.
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A new spatially telescoping approach was proposed to improve measurement flexibility and account for hydrologic scale in field studies of groundwater-surface water (GW-SW) interaction. We applied this spatially telescoping approach in a study GW-SW interactions along Lucile Creek, Alaska. Catchment-scale data were used to screen areas of potentially significant GW-SW exchange, indicating groundwater contribution from a deeper regional aquifer along the middle to lower reaches of the stream. This initial assessment was tested using reach-scale estimates of groundwater contribution during base flow conditions. The reach-scale measurements indicated a large increase in discharge along the middle reaches of the stream accompanied by a shift in chemical composition towards a regional groundwater end member. Point measurements of vertical water fluxes were used to evaluate spatial and temporal variability of GW-SW exchange within representative reaches. The spatially telescoping approach identified locations of GW-SW exchange and improved interpretation of reach-scale and point-scale measurements.
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Boereboom, Thierry. "Greenhouse gases investigations in ice from periglacial environments." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209673.
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L’environnement périglaciaire en général et les régions de permafrost en particulier, connus pour être très sensibles au changement climatique actuel, sont le sujet de beaucoup d’études sur les émissions de gaz à effet de serre. En effet, le dégel de ces milieux engendre la mobilisation d’une quantité importante de matière organique, précédemment piégée par le froid, favorisant les émissions de dioxyde de carbone et/ou de méthane. L’objectif premier, du présent travail, est de contribuer à l’étude des gaz enfermés dans certains types de glace de ces régions afin de mieux quantifier leur impact potentiel sur le climat.Dans un premier temps, une analyse multiparamétrique a été menée sur deux coins de glace du nord de la Sibérie dans la cadre d’une collaboration avec l’Alfred Wegener Institut (Allemagne). Cette première approche a révélé que l’analyse conjointe de la cristallographie, de l’orientation des axes optiques, du contenu en gaz total et de la composition en gaz des coins de glace est un outil puissant, complémentaire aux analyses des isotopes stables, pour comprendre les conditions paléo-climatiques qui ont régi la construction des coins de glace. Cette étude soutient également l’hypothèse de variations spatiales importantes de l’origine des masses d’air durant les variations climatiques du Pléistocène.
Dans un deuxième temps, une analyse des caractéristiques de la glace annuelle de 4 lacs du nord de la Suède a été réalisée afin d’étudier le rôle de la couverture de glace sur les émissions de gaz à effet de serre. En effet, les lacs de ces régions contribuent fortement aux émissions de méthane durant la période d’eau libre et très peu d’études ont analysé la quantité de méthane emprisonnée dans la glace hivernale et relâchée au printemps. Ce projet nous a amené à établir une nouvelle classification des bulles dans la glace de lac basée sur leur contenu en méthane, leur origine, leur forme et leur densité. Il nous a également permis de montrer que plusieurs facteurs interviennent sur le contenu en gaz dans la couverture de glace :le système hydrologique, la variation de la pression atmosphérique, la variabilité des émissions et potentiellement la proximité des sédiments sont autant de facteurs qui déterminent le contenu en gaz. L’analyse de la composition des gaz a révélé que la composition observée dans la glace est sensiblement différente de celle observée durant les périodes d’eau libre. Nous avons également, pour la première fois, établit un budget des émissions de méthane relâchées par la fonte de la couverture de glace au niveau mondial.
Cette étude a été complétée par l’analyse des isotopes 13C des gaz des différents types de bulles de notre classification en collaboration avec l’Université d’Utrecht. Nous avons alors mis en évidence que la couverture de glace influence l’équilibre biogéochimique dans l’eau en favorisant l’oxydation du méthane en dioxyde de carbone.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Lawson, Ian Thomas. "The late glacial and holocene environmental history of Greece." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621354.
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Burge, Philip Ian. "A Record of Environmental and Climatic Change from the West Coast, South Island, New Zealand, using Beetle Fossils." Thesis, University of Canterbury. Geological Sciences, 2007. http://hdl.handle.net/10092/1381.
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Fossil beetle based palaeoclimatic and palaeoenvironmental reconstructions are presented from the Westport region, West Coast, South Island, New Zealand for the last glacial cycle. They include the longest continuous fossil beetle record from New Zealand, covering 16,000 years over the OIS 3/OIS 2 transition. Early last glacial (OIS 4) and mid- Holocene (OIS 1) reconstructions are also presented. The assumptions underlying fossil beetle research in New Zealand are tested indicating beetles are suitable proxies for reconstructing palaeotemperature and palaeoprecipitation. This thesis provides the first quantitative estimates of temperature and precipitation from the Westport region for the last glacial. Reconstructed temperatures indicate stadial cooling was seasonal. Maximum cooling was ca. 5℃ in winter and ca. 2-3℃ in summer. Winter cooling is consistent with previous quantitative estimates from New Zealand. Mean annual precipitation decreased a maximum 35-40% during stadials. Temperatures and precipitation varied during OIS 3/2 indicating multiple possible drivers for glaciation. A glacial advance ca. 34-28ka BP correlates with ca. 5℃ winter cooling and ca. 40% less precipitation, which supports temperature driven glaciation whereas a glacial advance ca. 24-22ka BP correlates with ca. 3℃ winter cooling and precipitation similar to present, which supports precipitation forced glaciation. Palaeoenvironmental reconstructions of stadial vegetation from the Westport region indicate lowland Nothofagus fusca-type forest during OIS 4 and a forest-grassland mosaic during OIS 3/2. These records contrast with pollen-based reconstructions of a treeless landscape in Westport during stadials but are consistent with quantitative estimates of stadial cooling. A shift of reproductive strategy in arboreal vegetation may explain the lack of tree pollen in stadial pollen records. This is significant for our understanding of glacial palaeoecology and palaeoclimatology as pollen records may not accurately represent stadial vegetation.
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Stutz, James Edward II. "Reconstruction of LGM and Post LGM Glacial Environment of McMurdo Sound: Implications for Ice Dynamics, Depositional Systems and Glacial Isostatic Adjustment." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1324595182.
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Mountain, Keith Richard. "A clear sky net radiation model for the high elevation glacial environment /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487681148542966.
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Thompson, Kay Denise. "The stochastic characterization of glacial aquifers using geologic information." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12235.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1994.Includes bibliographical references (leaves 286-290).
by Kay Denise Thompson.
Ph.D.
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Tauro, Flavia. "Chilean glacial lake outburst flood impacts on dam construction." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53086.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2009.Includes bibliographical references (leaves 80-82).
Four Glacial Lake Outburst Floods (GLOF) occurred in the Colonia Glacier (Northern Patagonia Icefield, Chile) from April 2008 to March 2009. Lago Cachet 2 emptied four times producing a maximum excess discharge in the downstream Rio Baker of about 2,500 m3/s. These events have occurred at the same time as the proposal by HidroAysen to install two dams on the Rio Baker to produce hydropower. The aim of this thesis is to investigate the GLOF mechanisms and to estimate the magnitude of outburst flows to better understand their effect on the feasibility of the HidroAysen project. A temperature balance model for Lago Cachet 2 is developed to estimate the lake temperature before an outburst. These temperatures become inputs for the modified Clarke's model that predicts peak discharge of the lake given its geometry. The temperature model gave a lake temperature in January equal to 7.4 °C degrees that produces a peak discharge of approximately 2,000 m3/s, somewhat lower than the one registered at the confluence of the Rio Colonia with the Rio Baker (the station registered a peak discharge of 2,500 m3/s). A sensitivity analysis of the model to the various inputs suggests that model accuracy could be improved with more information about the geometry of Lago Cachet 2 and meteorological data. The study also illustrates how air temperature influences the melting of the Colonia Glacier and how the temperature trend is responsible for the GLOF frequency. A possible future scenario is proposed for Lago Cachet 2.
by Flavia Tauro.
M.Eng.
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Pugh, Jeremy Mark. "The late Quaternary environmental history of the Lake Heron basin, Mid Canterbury, New Zealand." Thesis, University of Canterbury. Geological Sciences, 2008. http://hdl.handle.net/10092/1766.
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The Lake Heron basin is an intermontane basin located approximately 30 kms west of Mount Hutt. Sediments within the basin are derived from a glacier that passed through the Lake Stream Valley from the upper Rakaia Valley. The lack of major drainage in the south part of the basin has increased the preservation potential of glacial phenomena. The area provides opportunities for detailed glacial geomorphology, sedimentology and micropaleontogical work, from which a very high-resolution study on climate change spanning the Last Glacial Maximum (LGM) through to the present was able to be reconstructed. The geomorphology reveals a complex glacial history spanning multiple glaciations. The Pyramid and Dogs Hill Advance are undated but possibly relate to the Waimaungan and Waimean glaciations. The Emily Formation (EM), previously thought to be MIS 4 (Mabin, 1984), was dated using Be10 to c. 25 ka B.P. The EM was largest advance of the Last Glacial Maximum (LGM). Ice during the LGM was at least 150m thicker than previously thought, as indicated by relatively young ages of high elevation moraines. Numerous moraine ridges and kame terraces show a continuous recession from LGM limits, and, supported by decreasing Be10 ages for other LGM moraines, it seems ice retreat was punctuated by minor glacial readvances and still-stands. These may be associated with decadal-scale climate variations, such as the PDO or early ENSO-like systems. There are relatively little sedimentological exposures in the area other than those on the shores of Lake Heron. The sediment at this location demonstrates the nature of glacial and paraglacial sedimentation during the later stages of ice retreat. They show that ice fronts oscillated across several hundred metres before retreating into Lake Heron proper. Vegetation change at Staces Tarn (1200m asl) indicates climate amelioration in the early Holocene. The late glacial vegetation cover of herb and small shrubs was replaced by a low, montane forest about 7,000 yrs B.P, approximately at the time of the regional thermal maxima. From 7,000 and 1,400 yrs B.P, temperatures slowly declined, and grasses slowly moved back onto the site, although the montane forest was still the dominant vegetation. Fires were frequent in the area extending back at least 6,000 years B.P. The largest fire, about 5,300 yrs B.P, caused major forest disruption. But full recovered occurred within about 500 years. Beech forest appears at the site about 3,300 yrs B.P and becomes the dominant forest cover about 1,400 yrs B.P. Cooler, cloudier winters and disturbance by fire promoted the expansion of beech forest at the expense of the previous low, montane forest. Both the increased frequency of fire events and late Holocene beech spread may be linked to ENSO-related variations in rainfall. The youngest zone is characterised by both a dramatic decline in beech forest and an increase in grasses, possibly representing human activity in the area.
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Jomier, Hugo. "Sediment dynamics of the pro-glacial Tarfalajaure, Kebnekaise." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-160486.
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The sensitive response of glaciers to climate change can be recorded in sediments, in glacier fed lakes. By studying sediments from pro-glacial lakes it is possible to determine how glaciers have reacted to past climate change and variability. Therefore, proglacial lake sediments cores can be used as proxy archives for climate and glacier activity reconstructions. The aim of this study is to detect any glacier signal in the lacustrine sediment cores from Tarfalajaure and seek for correlation with glacier processes and variations recorded in the past literature. Sediment cores were retrieved from the deepest part (52 m) of Tarfalajaure (65°55’25”,18°35’23”) in September 2016. Tarfalajaure is situated within the Swedish part of the Scandinavian Caledonides, in the Kebnekaise Mountains, northern Sweden. There are four glaciers draining into Tarfalajaure, Kebnepakteglaciären (the closest and largest one), Sydöstra Kaskasatjåkkaglaciären, Sydöstra Kaskasapakteglaciären and SydvästraKaskasatjåkkaglaciären. It is assumed that the variations of the minerogenic input and sediment characteristics in the cores over time reflect variations in glacier activity or changes in the proglacial environment. XRF measurements (Ti, Si, K, Fe, Ca, Mn/Fe, Zr/Rb, Ca/Ti,Fe/Ti, Si/Ti, K/Ca and K/Ti), magnetic susceptibility, grain-size analysis and radiocarbon dating have been used to detect variations in the sediment core. Comparisons have been made with results from other studies of glacier activity in northern Scandinavia, and with reconstructions of temperature variation during the last millennia. The results indicate several periods of glacieradvances which were also identified in other studies. These advances occurred around 25 cal BP, between 300 and 375, 1000 and 1150 cal BP, and around 700 – 800, 1900, and 2200 –2275 cal BP.
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Callahan, Colin M. "Continental-scale characterization of molecular variation in quaking aspen." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1297.
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Quaking aspen (Populus tremuloides) has the largest natural distribution of any tree native to North America, ranging from Alaska through the breadth of Canada and south to mid-Mexico. The Laurentide ice sheet occupied most of the current range of P. tremuloides until the late Pleistocene epoch, so this species has undergone a significant, geologically recent range expansion. Surprisingly, range-wide patterns of genetic variation in P. tremuloides have never been described. Using a sample set representing the full longitudinal and latitudinal extent of the species distribution, I have conducted a phylogeographic analysis for P. tremuloides. Preliminary results comparing both nuclear and chloroplast DNA sequences revealed surprisingly low levels of divergence across the range. Because of this remarkably shallow genetic divergence among aspen populations, I used a set of rapidly-evolving molecular markers (microsatellites) to describe patterns of gene flow and diversity and to correlate those patterns with landscape features and histories. I analyzed eight microsatellite loci in 794 individuals from 30 sampling sites. From this multilocus data set, I identified pronounced genetic structuring across the range. Strikingly, sampling sites representing the southwestern portion of the range, the western United States and Mexico, form a distinct cluster. Sites within this southwestern cluster display dramatically reduced within-site genetic diversity but elevated regional genetic diversity, which suggests that populations in the southwestern portion of the range make up a stable edge persisting through multiple climate oscillations. Based on the uniqueness of the southwestern cluster and the climatic differences between the southwest and northern portions of the range, I propose that the southwestern cluster may represent a distinct ecotype. I also identified hotspots of diversity that correspond with potential refugia during the last glacial maximum but additional work is needed to refine these patterns. Further, my findings provide a solid foundation for a range of future studies on adaptive genetic and trait variation in this species.
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Gervais, Francoise. "Fate and Transport of Naphthenic Acids in Glacial Aquifers." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/1229.
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Naphthenic acids (NAs) are carboxylated alkanes and cycloalkanes concentrated in wastewater during oil sands processing. The general chemical formula is C{n}H{n+Z}O{2}, where n represents the number of carbon atoms and Z specifies a homologous family with 0-6 rings (Z=0 to Z=-12). The wastewater is acutely toxic to surface water organisms and is stored in tailings ponds with over 230 million m³ of fines tailings and free water. The purpose of this thesis was to provide a preliminary evaluation of the potential attenuation of NAs during groundwater flow from the ponds. Laboratory studies were conducted to evaluate possible attenuation mechanisms. Aerobes from aquifer material degraded 60% of the NAs over 20 weeks in laboratory microcosms. The greatest decrease occurred in the low molecular weight bicyclic homologues with 12 to 16 carbons. The microbial activity confirms that aerobic naphthenate-degrading bacteria occur naturally in the glacial aquifer near Suncor's Pond 2/3. These results support the hypothesis that limited aerobic biodegradation of the smaller components of NAs could occur relatively rapidly under field conditions. There was no measurable decrease in NA concentration over six months in anaerobic microcosms, although microbial activity did lead to sulfate-reducing and methanogenic conditions. The theoretical retardation in glacio-fluvial sands was calculated using soil-water partitioning coefficients (K{d}) determined by batch equilibration experiments using a mixture of naturally occurring naphthenic acids as well as the nine surrogates. The retardation (porosity of 0. 3, bulk density of 1. 5 g/mL) ranged from 1. 2 to 2. 6. However, no measurable sorption was seen at the field sites. Detailed characterization allows us to examine how the proportions of homologue, or groups of molecules with the same molecular weight and number of cycloalkane rings, vary. Aerobic biodegradation favoured removal of low molecular weight NAs. A 15% mass loss attributed to sorption caused no changes in the 3D signature. Thus, changes in NA "signature" in groundwater systems were then attributed to aerobic biodegradation. Three plumes were examined for evidence of attenuation of NAs via biodegradation. First, the individual samples were classified as background, possibly process-affected or process-affected using a combination of Piper diagrams, the stable isotopes oxygen-18 and deuterium, dissolved chloride and sodium, as well as the total naphthenic acids concentration. Second, in order to estimate attenuation due to dispersive dilution, a linear correlation line was drawn between various conservative tracers and the naphthenic acids concentration. This allowed the identification of certain samples as possibly having a lower concentration of NAs than could be expected from simple dispersive dilution. Third, the 3D signature of certain samples were examined for the presence of the aerobic biodegradation 3D signature. One site showed good evidence for aerobic biodegradation of naphthenic acids. A second site showed some evidence for biodegradation under methanogenic conditions but the evidence was not definitive. The evidence at the third site was contradictory and no conclusions could be drawn from it. This research suggests some attenuation of NAs by biodegradation may be possible during groundwater flow.
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Jones, Gwydion. "Constraining Late-glacial and early Holocene environmental changes in Wales and Germany using tephrochronology." Thesis, Swansea University, 2018. https://cronfa.swan.ac.uk/Record/cronfa39863.
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Evidence for the abrupt Late-glacial climatic changes is observed in many palaeorecords, however the mechanisms and triggers behind these changes are still unknown. The preferred hypothesis is thought to be linked with the disruption in the North Atlantic Ocean circulation, therefore palaeoclimatic records from maritime regions are needed to investigate the impact of these abrupt changes. The Greenland ice-core records provide high-resolution evidence of these changes, in addition to many marine and terrestrial records throughout the North Atlantic. However, there is a lack of studies on sites in the south western coastal regions of the British Isles that are well-constrained by robust chronologies. The latter, in particular, hampers our understanding of the mechanisms driving the rapid climate changes of the Lateglacial due to the difficulties of integrating and comparing the climatic response in diverse proxy records. In an attempt to resolve these challenges tephrochronology was employed as a precise correlation technique to investigate three Lateglacial sequences from Wales (Llyn Llech Owain, Cors Carmel and Pant- y-Llyn). An additional site from north Germany (Lake Hämelsee) was also included in this study and chosen due to its potential to preserve tephra from more than one volcanic region and develop a European tephra framework or stratotype for the Lateglacial. Twenty-one tephra deposits were identified across the network of sites. Twelve deposits have been correlated to known eruptions and in most cases have extended the geographical distribution of their respective ash dispersal. Icelandic tephra deposits of Lateglacial age such as the Askja-S Tephra have been discovered in Welsh sites for the first time highlighting the potential of employing tephrochronology more widely in areas such as Wales, south England and perhaps France. Furthermore, three non-Icelandic deposits, that originate from the Cascade region, Alaska and Italy, have been discovered in the Llyn Llech Owain record, allowing the synchronisation of records across a trans-continental scale. The Askja-S Tephra, Ulmener Maar Tephra and Vedde Ash are added to the tephrostartigraphy of the Hämelsee record highlighting its importance as a key site within the European tephra lattice. Nine of the discovered tephra deposits in Llyn Llech Owain and Lake Hämelsee have not been correlated and may represent new eruptions and potentially new tephra isochrons for future studies. Tephra results are supplemented by multi-proxy palaeoenvironmental reconstructions including lithostratigraphic data, sediment geochemistry, palaeoecology and radiocarbon dating where possible. In addition to providing fix-points for potential age-models, the discovered tephra deposits allow the study sites to be independently synchronised with other tephra bearing sites. This allows investigations to be made between sites to constrain any leads or lags in the environmental response to climate change and in turn help determine the mechanisms that cause these abrupt climate changes.
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Gheorghiu, Delia Mihaela. "Testing climate synchronicity between Scotland and Romania since the last glacial maximum." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3362/.
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This thesis develops a chronology of ice retreat in the Monadhliath Mountains (Scotland) and Rodna Mountains (Romania) during the late Pleistocene using glacial geomorphology and surface exposure dating with cosmogenic 10Be. In the Monadhliath Mountains, 10Be exposure ages indicate deglaciation of the Last Devensian ice sheet at 15.1 ka (n = 2). Boulders from moraines in three Monadhliath cirques yielded exposure ages between 11.8 ka and 9.8 ka (470 – 600 m), suggesting that a Late Glacial readvance occurred during the Younger Dryas stadial (n = 9). The limited extent of these YD glaciers in the Monadhliath Mountains is explained in terms of the drier climate experienced by the eastern part of the Central Highland ice cap, but also in terms of local factors such as topography and snow blow. The resulting glacial reconstruction largely confirms that a SW to NE precipitation gradient dominated Scotland during the Younger Dryas. In the Romanian Carpathians, located at the southern periphery of the NW European ice sheet, there was only limited coverage of ice, mostly at higher elevations in the form of mountain glaciers. Field evidence suggests that during the last local maximum glaciation ice reached lower elevations than previously suggested in the Rodna Mountains. Glacially transported boulders were abandoned at 37.2 – 26.6 ka (n = 4) at an elevation of ~900 m. Glacial erratics and bedrock samples (n = 27) provide a consistent chronology for deglaciation during the Lateglacial, suggesting that ice retreated towards higher ground between 18.3 – 13.2 ka (1100 – 1800 m altitude). Final deglaciation took place at 12.5 - 11.2 ka (n = 9). These new chronologies are compared to other climate archives in Europe and the climatic oscillations recorded in the North Atlantic region. This analysis increases our understanding of past atmospheric circulation across Europe, and gives insights into the climatic forcing mechanisms during the last maximum extent of ice sheets and glaciers. During the last glacial episodes, the pattern of climate cooling from the western high latitudes towards the eastern mid latitudes was complicated, triggering different responses in local climates that appear to have been out of phase with the broader north-western European trend. Located in the NW Europe, Scotland was influenced by the wetter and colder conditions from the Atlantic which led to the expansion of the British Ice sheet during the global Last Glacial Maximum (LGM). However, smaller ice masses located further southwards and south-eastwards of the European ice sheet responded faster to the climatic oscillations in the North Atlantic region. During the LGM, the southward repositioning of the Polar Front and the presence of the ice sheet changed the atmospheric circulation across Europe. There was limited supply of moisture to the Rodna Mountains, especially because of blocking by the eastern Siberian high pressure system, and the glaciers experienced a slow retreat in a very cold and dry environment. However, a more synchronous Younger Dryas is likely to have occurred due to a more northern position of the Polar Front. This allowed for stronger wet and cold westerly winds to reach most of Europe at the same time.
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Quiroga, Allison. "Carbon Flux and Weathering Processes in Icelandic Glacial-Fed Rivers." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/2568.
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An investigation into the carbon dynamics and weathering processes occurring in Icelandic glacial-fed streams was conducted during the spring to summer seasonal transition in June of 2017. Four major outlet rives were sampled from the glaciers of Gígjökull, Steinsholtsjökull, Sólheimajökull, and Falljökull. Markarfljót, the major river that Gígjökull, Steinsholtsjökull, and many other glaciers drain into, was also sampled. Longitudinal sampling occurred at all sites to capture downstream trends in the hydrogeochemistry and carbon dynamics. Distinct differences in geochemistry between glacier surface meltwater, sub-glacial waters, pro-glacial lake water, and post-mixed downstream samples were evident in the data. Glacier surface streams were characterized by relatively colder water temperatures, lower specific conductivity, lower total dissolved solids (TDS) and ion concentrations, and more enriched δ13CDIC values than downstream samples. The THINCARB model was used to calculate the total dissolved inorganic carbon (TDIC), excess partial pressure of carbon dioxide (EpCO2), and percent contribution to TDIC by bicarbonate (HCO3), carbonate (CO3), and carbonic acid and dissolved CO2 (H2CO3). All sites showed a slight decreasing trend in DIC and EpCO2 downstream. The calculated CO2 flux ranged from 1.14 × 107 g/yr to 2.80 × 109 g/yr. The DIC flux ranged from 6.81 × 107 g/yr to 8.44 × 109 g/yr. The average carbon within the CO2 fluxing in these rivers accounts for 0.0004% of the annual, global flux of carbon. The δ13C values were the most variable throughout the study and indicate there are multiple sources influencing the river downstream. This study suggests that, despite previous assumptions and estimations, these glacial-fed rivers act as sources of CO2; however, the samples from this study only provide a snapshot into the carbon flux dynamics during the Spring to Summer seasonal transition. In most samples, HCO3 was the dominant species contributing to DIC content within the rivers, suggesting that DIC is being transported to the ocean as HCO3 but sourced to the atmosphere as CO2. By acting as sources of CO2 to the atmosphere, the process of glaciers melting, which drive geochemical processes within the rivers, are contributing to a positive feedback loop with respect to global warming.
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Schild, Kristin Meredith. "Terminus Changes of Tidewater Outlet Glaciers in Greenland: Environmental Controls and Links to Glacial Earthquakes." Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/SchildKM2011.pdf.
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Tingdal, Love, and Nils Ceder. "The behaviour of melt water within a glacial system." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324566.
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A glacier contains of many different layers of different properties. Each layer is formed during a calendar year similar to tree rings and their layers. A glacier has two different zones, the first one referred to as accumulation zone, where the addition of snow exceeds the loss of snow. The second, the ablation zone, is the zone where the loss of snow exceeds the addition of snow. These two zones are divided by the equilibrium line, where the addition of snow equals the loss of snow. Lenses of ice, caused by the summer melt, usually divide the horizontal layers within the glacier from one another. During the winter, snow will accumulate on top of the glacier and during the upcoming summer, the same snow will partly melt due to solar radiation. Some of this meltwater will penetrate the ice lenses and the layers of snow beneath, while some of it will refreeze as the winter once again returns. As the seasons change, freshly fallen snow will be compacted and somewhat water saturated. Compaction will lead to air passages being sealed off into separate air bubbles, which also leads to a change in density; a fixed volume gets heavier due to ongoing compaction. Snow that gets compacted turns into firn which has a larger mass per volume than snow does. Further compaction leads to glacier ice. The purpose of this study is to determine what effect the ice lenses has on the permeating meltwater and whether differences in snow density have similar effects. To achieve this purpose, a glacier was simulated inside a freezing room, with the help of a box that was packed with a few layers of snow. The amount of layers represented the same amount of years for a natural glacier. The experiment was performed twice, once without ice lenses but with varying densities and once with ice lenses but with similar densities. The very top layer was dyed red to track the descending meltwater accurately. To cause the melting, five infrared lamps were used to simulate solar radiation on the very top.En glaciär består av många olika lager med olika egenskaper. Var lager uppstår under ett kalenderår likt trädringar och de lager de består av. En glaciär har två olika zoner. Den första benämns som ackumulationszonen, där tillförseln av snö överskrider förlusten av snö. Den andra, ablationszonen, är den zon där förlusten av snö överstiger tillförseln av snö. Dessa två zoner skiljs åt av jämviktslinjen, där tillförseln av snö är lika med förlusten av snö. Islinser, som skapas av sommarens smältvatten, skiljer oftast de horisontella lagrena inom glaciären åt. Under vinterhalvåret ansamlas snö på glaciärytan och smälter delvis under sommaren av värme från solen. En del av detta smältvatten penetrerar islinserna och den underliggande snön, medan en del av det åter smälter under vintern. När säsongerna ändras kompakteras snön och blir delvis vattenmättad. Kompaktion leder till att passager inom isen separeras till enskilda luftbubblor, vilket också ökar densiteten; en specifik volym får högre massa på grund av ett ökat tryck. Snö som kompakteras övergår till firn, vilket har högre massa i förhållande till volymen än vad snö har. Fortsatt kompaktion leder till att firnen övergår till en glaciäris. Syftet med denna studie är att bestämma vilken effekt islinser har på perkolerande smältvatten och om skillnader i densitet hos snö har liknande påverkan. För att uppnå detta syfte simulerades en glaciär i ett frysrum, med hjälp av en låda som packades med några lager snö. Mängden lager representerade samma antal år i en naturlig glaciär. Experimentet utfördes två gånger, en gång utan islinser men med varierande densitet och en gång med islinser men med liknande densitet. Det översta lagret färgades rött för att kunna undersöka det sjunkande smältvattnet exakt. För att ge upphov till smältan användes fem infraröda lampor för att representera solens strålar längs ytan.
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Collins, Philip E. F. "Floodplain environmental change since the last glacial maximum in the Lower Kennet Valley, South-Central England." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294864.
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The lower Kennet Valley terraces reflect fluctuations in river regime through the Quaternary. Sediments and valley floor geomorphology provide a detailed record of Devensian and Flandrian fluvial behaviour and environmental change. Two major surfaces occur, the floodplain and the Beenham Grange Terrace (2 - 3m above the floodplain). Levelling showed that the terrace south of the river, underlain by deposits of two Early Devensian interstadials, was part of the Beenham Grange level, and not the Thatcham Terrace as previously proposed. The fluvial succession consisted of the subflood plain Midgham Peat Formation overlying the Woolhalllpton Gravel Formation The latter also rises to form the surface of the Beenham Grange Terrace adjacent to the floodplain. A subunit of the Woolhampton Formation, the Heales Lock Gravel Member, thickened over a large depression in the local Tertiary bedrock and was associated with syndepositional subsidence which aided excellent subfossil preservation in the sediments. A major channel fill within the member - the Wasing Sand Bed - contained Betula with a distinctive herb flora which, with 14C data, indicates a correlation with the Late Devensian Windermere Interstadial. Lithostratigraphy, biostratigraphy and 14C data from gravels resting unconformably on the Wasing Sand indicated a Loch Lomond Stadial age. The sedimentology of the Midgham Peat Formation reflected early Flandrian reductions in flow competence associated with silt, peat and tufa deposition. Regional woodland expansion was followed by alder can' closing of the floodplain during the Atlantic. A subsequent hiatus ended ,with Sub-boreal (?Bronze Age) flooding and deposition, perhaps anthropogenically induced. An upper silt reflects lower energy flooding in an agricultural landscape. To avoid taphonomic difficulties macrofossil interpretations utilised only well-preserved material. Pollen taphonomy was more problematic. A pilot study in subarctic Canada suggested that, while fluvial pollen assemblages were not exactly equivalent to regional pollen rain through local inputs and sorting, vegetation changes were identifiable.
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Chaney, Alistair John. "Sedimentology, facies architecture and hydrocarbon potential of the Merrimelia Formation (glacial Permo-Carboniferous), Southern Cooper Basin, South Australia." Thesis, University of Aberdeen, 1990. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU125529.
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Sedimentological analysis of cored sections within the Merrimelia Formation (basal Gidgealpa Group, Cooper Basin, South Australia) reveals a complex glacigenic environment, including glaciolacustrine, deltaic, shorezone, fluvial, aeolian and other associated terrestrial facies (over 20 different facies have been identified). These facies are observed within terminoglacial and proglacial environments and interfinger laterally and vertically constantly throughout the Merrimelia Formation, exhibiting rapid environment change related to the position of ice sheet. Detailed sedimentological and petrographical (Cubitt 1998) analysis suggests that Tirrawarra sandstone-type sandstones facies belong within the Merrimelia depositional realm. Provenance data (Cubitt 1998) indicates that the lithic component of the Tirrawarra Sandstone (sensu stricto), is sourced from reworked Merrimelia coeval depositional facies. It is proposed that the fluvial sandstones of the Merrimelia Formation are part of the same fluvial deposystem as the Tirrawarra Sandstone (sensu stricto) as the two sandstone sequences are the natural progression of coarsening sediment as more detritus was released from melting glaciers during deglaciation. It is suggested that there no longer remain any sedimentological, stratigraphical or petrographical (Cubitt 1998) reasons why the Tirrawarra Sandstone (sensu stricto) and the Merrimelia Formation glaciofluvial sandstones should not be grouped together as Tirrawarra-type facies within the Merrimelia glacigenic domain. Facies architecture across the basin on both field and basin wide scales has identified two regional lacustrine episodes, both of which are followed by a period of lacustrine basin clastic infill. Such cycles represent ice advance and retreat, allowing two deglaciation phases and one ice advance phase to be identified.
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Huh, Kyung In. "Reconstructing Holocene Glacier changes in West Greenland from multispectral imagery." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1407141572.
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Guido, Zack, Jennifer C. McIntosh, Shirley A. Papuga, and Thomas Meixner. "Seasonal glacial meltwater contributions to surface water in the Bolivian Andes: A case study using environmental tracers." ELSEVIER SCIENCE BV, 2016. http://hdl.handle.net/10150/626096.
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Study region: The Cordoriri watershed and vicinity in the Cordillera Real, Bolivia, South America Study focus: Recent warming has contributed to substantial reductions in glaciers in many regions around the globe. Melting of these glaciers alters the timing and magnitude of streamflows and diminishes water resources accumulated in past climates. These changes are especially acute in regions with small glaciers and problematic for populations relying on surface water. In Bolivia, most glaciers are less than 0.5 km(2) and about 2 million people draw water in part from glacier-fed watersheds. Sparse monitoring, however, has limited estimates of glacial meltwater contributions. The use of environmental tracers is one approach that can quantify the contributions of glaciers. We present isotopic and anion data for streams, reservoirs, arroyos, precipitation, and glaciers for the wet and dry seasons in 2010, 2011, and 2012. New hydrological insights for the region: Glacier meltwater data shows distinct seasonal isotopic values, presenting opportunities for end-member mixing analyses. From isotopes, we estimate 31-65% of the water measured in high altitude streams and reservoirs during the 2011 wet season originated from melting of ice and recent snow, while glacier ice contributed 39-71% of the water in reservoirs in the 2012 dry season. This study demonstrates that more comprehensive sampling in the region could quantify the contributions of glacial meltwater and nonglacial sources to surface water supplies. (C) 2016 The Author(s). Published by Elsevier B.V.
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Gura, Colby J. "Characterization of Organisms in Vostok (Antarctica) Glacial, Basal, and Accretion Ice." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1566486484767222.
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Christner, Brent C. "Detection, recovery, isolation, and characterization of bacteria in glacial ice and Lake Vostok accretion ice." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1015965965.
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Bendle, James Alexander Paul. "Palaeoceanography of the Holocene and late-glacial N.E. Atlantic : development and application of biomarker proxies of environmental change." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/4019/.
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The aim of this thesis is to develop and apply novel climate proxies to understand the palaeoceanographic evolution of the N.E. Atlantic during the late-Glacial and Holocene. The proxies investigated are based on organic molecular compounds called lipid biomarkers and bulk organic matter properties. The primary focus is on long-chain alkenones, molecules which have been extensively used in mid and low latitude open oceans to reconstruct sea surface temperatures (SSTs) during the Quaternary. Thus, the relative abundance of some alkenones is related to the growth temperature of the algae at the time of the biosynthesis of these molecules (expressed in the U(^K)(_37) and U(^K)(_37)’ indices). In high latitudes and coastal environments, the temperature dependence of alkenones is controversial, and the potential environmental information from alkenones is not yet well understood. In such locations there is increasing abundance of the C(_37:4) alkenone (quantified as %C(_37:4)). The presence of this component has been related to changes in the relative budget of freshwater in the surface ocean. A central aim of this thesis is to carry out an empirical investigation to find out the key environmental factors that control %C(_37:4) to assess its potential as a palaeoceanographic proxy. Research was conducted in the Nordic Seas and N.W. Scotland using samples from the water column, surficial sediment and sediment cores. The research undertaken can be broken down in three main sections: Alkenone distributions in the Nordic Seas. The aim was to clarify and extend the application of alkenones as palaeoceanographic proxies in subpolar to polar environments. Samples of filtered sea surface POM were analysed and extremely high %C(_37:4) values (up to 77%) were measured in polar waters (up to 80% sea-ice cover). Values of %C(_37:4) across the Nordic Seas showed a strong association with water mass type. A combined data-set revealed a stronger correlation of %C(_37:4) to sea surface salinity' (SSS, R(^2) = 0.72) than to SST (R(^2) = 0.5). However, scatter was observed in the relationship of %C(_37:4) to SSS, preventing confirmation of %C(_37:4) as a palaeo-SSS proxy. Values of %C(_37:4) in sea surface POM were high compared to surficial sediments. We discount preferential degradation of the %C(_37:4) alkenone and invoke dilution of the %C(_37:4) signal in sea surface sediments by advected allochthonous matter to explain this. The POM filter data suggest that, overall, U(^K)(_37) is a more appropriate SST index for the Nordic Seas than U(^K)(_37) '. Examination of the scatter in the U(^K)(_37) ' versus SST relationship, shows that regions in the south of the Nordic Seas (including the Icelandic shelf) may yield reliable, alkenone based, palaeoceanographic reconstructions. Comparison of %C(_37:4) distributions with dinocyst proxies in a late Holocene core from the Barents Sea suggests %C(_37:4) may be a general marker for the influence of arctic/polar water in palaeoceanographic reconstructions. The palaeoceanography of the Icelandic shelf iox. the post-Glacial period (0-15 kyr BP) was reconstructed from alkenone indices measured in three cores collected N and W of Iceland. One of the cores, JR51-GC35, contained a continuous record of Holocene sedimentation spanning 0 - 10.1 kyr BP. Superimposed on a general Holocene cooling trend in core JR5I-GC35 were millennial scale oscillations of ~2 C. The timing of the oscillations was in close agreement with the variability in IRD records from the East Greenland shelf and the timing of glacier advances in northern Iceland. A comparison of the U(^K)(_37) -SST records from JR51-GC35 and a published core from the eastern Nordic Seas (MD952011) showed significant differences (superimposed on the general trend) in the timing of millennial scale climate events. This illustrates that Holocene climate evolution in the Nordic Seas was more complex than previously suggested, with significant climatic differences between the eastern and western Nordic Seas caused by the differential variability of the Irminger and Norwegian Currents with time. The potential application for reconstructing past sea-level changes in NW. Scotland of lipid biomarkers (alkenones, n-alkanes and chlorophyll derivatives), and bulk organic parameters (%TOC, C(_nrg)/N) was assessed by a survey of modern basins (at different stages of isolation from the sea) and fossil basins (with known sea-level histories). A logit regression analysis of all the sediment samples was employed to find which of the biomarkers or bulk organic measurements could reliably characterize the sediment samples in terms of a marine/brackish or isolated/lacustrine origin. The results suggested an excellent efficiency for the alkenone index %C(_37:4) at predicting the depositional origin of the sediments. This study suggests alkenones could be used as an indicator of sea-level change in fossil isolation basins.
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Hemsing, Freya [Verfasser], and Norbert [Akademischer Betreuer] Frank. "Cold-Water Corals as Archives for Ocean Dynamics, Environmental Conditions and Glacial Reef Accumulation / Freya Hemsing ; Betreuer: Norbert Frank." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://d-nb.info/1177690632/34.
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Stanich, Nicholas A. "SOIL PHYSICAL PROPERTY CHARACTERISTICS AND CHRONOSEQUENCE ANALYSIS ABOUT A GLACIAL FORE-FIELD IN SKAFTAFELLSJOKULL, ICELAND." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366613027.
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Fair, Heather Lynne. "Ecology of aquatic insects in monsoonal temperate glacier streams of Southeast Tibet: A departure from the conceptual model." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512032478760477.
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Wyshnytzky, Cianna E. "On the mechanisms of minor moraine formation in high-mountain environments of the European Alps." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25992.
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Groups of closely spaced minor moraines allow for observations of moraine formation and ice-marginal fluctuations on short timescales, helping to better understand glacier retreat and predict its geomorphological effects. Some minor moraines can be classified as annual moraines given sufficient chronological control, which implies a seasonal climatic driver of ice-marginal fluctuations. This leads to moraines being utilised as very specific, short-term records of glacier fluctuations and climate change. This research is common in lowland, maritime settings, but remains sparse in high-mountain settings. This study presents the detailed geomorphological and sedimentological results of minor moraines at two high-mountain settings in the European Alps. Geomorphological investigations included mapping and measurements through field observations and remotely-sensed imagery. Detailed sedimentological investigations followed excavation of moraines and include multiple scales of observation and measurements to support interpretations of sediment transport and deposition. Additionally, ground-penetrating radar data were collected in one foreland. Minor moraines at Schwarzensteinkees, Austria, formed as push or combined push and freeze-on moraines in two groups between approximately 1850 and 1930. The existence of a former proglacial lake appears to have exerted a strong control on moraine formation. Modern minor moraines at Silvrettagletscher, Switzerland, exist primarily on reverse bedrock slopes and have formed since approximately 1850 through push, freeze-on, and controlled moraine mechanisms. The presence of these bedrock slopes, and in some areas englacial debris septa, appear to exert the primary controls on moraine formation. The foreland of Gornergletscher, Switzerland, has been revisited using aerial imagery to assess if moraines are still forming annually, and this has been confirmed. These findings show a range of mechanisms responsible for moraine formation, which are then compared to previously published research on minor moraines to elucidate any common drivers of minor and annual moraine formation globally. This includes a global database of forelands where minor moraines have been studied, created as part of this research and presented as a table and Google Earth file, both easily accessible and freely available online, for use by other researchers when exploring similar topics.
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Wilde, Tim Gerard. "Public participation in the environmental assessment of the Jumbo Glacier ski area proposal." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0001/MQ37665.pdf.
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Turner, Chloe Michele. "Soil chemical properties dynamics in glacial moraines across a chronosequence: Breiðamerkurjokull outwash plane, Iceland." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1525601525183877.
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Nel, Werner. "A spatial inventory of glacial, periglacial and rapid mass movement forms on part of Marion Island : implications for Quaternary environmental change." Diss., University of Pretoria, 2001. http://hdl.handle.net/2263/62973.
Full textAbstract:
While climate change is expected to have its greatest impacts in the earth's
polar regions, most studies to date concentrate on Northern Hemisphere landscape
changes. In contrast, Southern Hemisphere periglacial environments are poorly
understood, both in terms of basic understanding of geomorphological dynamics as
well as sensitivity to climate change. Marion Island constitutes such an environment
and the purpose of this project was to assess the Late Pleistocene and Holocene
glacial, periglacial and mass movement morphology on the island, and to use these
data as indicators for climate change. A survey and thematic mapping, following an
adaptation from the lTC working procedure, was used to compile an inventory of the
glacial, periglacial and mass movement features for grey lavas on the eastern side of
Marion Island.
Glacial moraines, glacially polished and striated bedrock surfaces identified
from previous research verified and mapped, while undocumented sites were added to
the inventory. Data support the findings of Hall (1978; 1980a; 1982) and that the
suggested palaeoreconstruction and glacial succession on Marion Island from that
research is correctly interpreted.
Periglacial landforms occur Qn all the grey lava areas that were surveyed on
Marion Island. The features are found throughout the whole island altitudinal range,
and definite trends can be discerned, where landform size increases with altitude. No
significant differences, however, appear to exist between the warmer north-facing and
colder south facing slopes with regards to the size distribution of periglacial features on Marion Island. Increasing periglacial activity with altitude is indicative of an increase in
frequency and/or intensity of frost induced processes.
Stone-banked lobes, stone-banked terraces, vegetation-banked lobes and
blockstreams identified in this study and whose morphology cannot be explained by
present day soil frost activity are considered relict. These features indicate and confirm
conclusions from previous studies that Marion Island experienced a more severe frost
environment than present.
Rapid mass movement features are present in most grey lava areas, except
where there is an absence of cliffs or where low slope angles are found. Screes are
mostly found where high free faces exist and the extent of the screes is related to the
morphology of the cliffs above. Peat slides are common in middle and low altitudinal
areas between 150m a.s.l. and 450m a.s.l. where thick soil and steeper slopes are
present. However, peat slides are conspicuously absent form the feldmark
environments due to a lack of peaty soil. Most peat slides on Marion Island occur on
the north facing slopes of the major ridgelines. It is concluded from observations that
major scree production occurred during a period of more intensive periglacial activity
during the early Holocene lasting from 12kBP until 7kBP.
The area demarcated as Feldmark Plateau, is bounded by faults due to
isostatic uplift on deglaciation, which indicates that the ice cover in this region must
have been extensive. However, no irrefutable proxy evidence for glacial activity has
been found in this area. Periglacial features on the Feldmark Plateau are relatively
larger than the same landforms in other areas at similar altitudes and possible reasons
for this could be that the Feldmark Plateau was not glaciated in the Pleistocene; the
features would then have developed under a cold, but ice-free environment. It should
be noted that all slopes of the Feldmark Plateau are south facing and thus receive less
insolation than north facing slopes. In addition, the slopes occupy the southern sector
of the island, which may further contribute towards a cooler and more intense frost
environment. It is hypothesised that a period of intense scree production occurred
during the early Holocene, and this is manifested in the scree on the slopes of the
Feldmark. If glaciation did occur, over-steepend slopes following ice retreat, would
also have been conducive to intense scree production. It can, therefore, be concluded
that the Feldmark Plateau, if glaciated, became ice-free rapidly after glaciation, so that
the intense periglacial activity, plus the oversteepend slopes left by the glacial activity,
produced large amount of scree from the cliffs. The inventory of periglacial, glacial and mass movements on grey lava areas of
Marion Island provides a useful baseline for geomorphological studies on Marion
Island. Through refinement this database has the potential for palaeoenvironmental
research and is a useful resource for earth and biological scientific studies.Dissertation (MSc)--University of Pretoria, 2001.
Geography, Geoinformatics and Meteorology
MSc
Unrestricted
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Waibel, Michael Scott. "A Numerical Model Investigation of the Role of the Glacier Bed in Regulating Grounding Line Retreat of Thwaites Glacier, West Antarctica." Thesis, Portland State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10259298.
Full textAbstract:
I examine how two different realizations of bed morphology affect Thwaites Glacier response to ocean warming through the initiation of marine ice sheet instability and associated grounding line retreat. A state of the art numerical ice sheet model is used for this purpose. The bed configurations used are the 1-km resolution interpolated BEDMAP2 bed and a higher-resolution conditional simulation produced by John Goff at the University of Texas using the same underlying data. The model is forced using a slow ramp approach, where melt of ice on the floating side of the grounding line is increased over time, which gently nudges the glacier toward instability. Once an instability is initiated, the anomalous forcing is turned off, and further grounding line retreat is tracked.
Two model experiments are conducted. The first experiment examines the effect of different anomalous forcing magnitudes over the same bed. The second experiment compares the generation and progress of instabilities over different beds. Two fundamental conclusions emerge from these experiments. First, different bed geometries require different ocean forcings to generate a genuine instability, where ice dynamics lead to a positive feedback and grounding line retreat becomes unstable. Second, slightly different forcings produce different retreat rates, even after the anomalous forcing is shut off, because different forcing magnitudes produce different driving stresses at the time the instability is initiated. While variability in the retreat rate over time depends on bed topography, the rate itself is set by the magnitude of the forcing. This signals the importance of correct knowledge of both bed shape and ocean circulation under floating portions of Antarctic ice sheets. The experiments also imply that different ocean warming rates delivered by different global warming scenarios directly affects the rate of Antarctic contribution to sea level rise.
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Rees, Hefin Gwyn. "Potential impacts of climatic warming on glacier-fed river flows in the Himalaya." Thesis, University of Salford, 2014. http://usir.salford.ac.uk/34042/.
Full textAbstract:
The Himalayan region is one of the most highly glacierised areas on Earth. Regarded as the “water towers” of Asia, the Himalayas are the source of several of the world’s major rivers. The region is inhabited by some 140 million people and ten times as many (~1.4 billion) live in its downstream river basins. Freshwater from the mountains is vital for the region’s economy and for sustaining the livelihoods of a fast-growing population. Climatic warming and the rapid retreat of Himalayan glaciers over recent decades have raised concerns about the future reliability of mountain melt-water resources, leading to warnings of catastrophic water shortages. Several previous studies have assessed climate change impacts on specific glacier-fed rivers, usually applying meso-scale catchment models for short simulation periods during which glacier dimensions remain unchanged. Few studies have attempted to estimate the effects on a regional scale, partly because of the paucity of good quality data across the Himalaya. The aim of this study was to develop a parsimonious grid-based macro-scale hydrological model for the Indus, Ganges and Brahmaputra basins that, in order to represent transient melt-water contributions from retreating glaciers, innovatively allowed glacier dimensions to change over time. The model initially was validated over the 1961-90 standard period and then applied in each basin with a range of climate-change scenarios (sensitivity analysis- and climate-model-based) over a 100-year period, to gain insight on potential changes in mean annual and winter flows (water availability proxies) at decadal time-steps. Plausible results were obtained, showing impacts vary considerably across the region (catchments in the east appear much less susceptible to glacier retreat effects than those in the west, due to the influence of the summer monsoon), and, in central and eastern Himalayan catchments, from upstream to downstream (effects diminish rapidly downstream due to higher runoff from non-glaciated parts).
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Jankowiak, Aleksy. "La détermination du statut juridique de l'océan Glacial arctique par le droit international public." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0170.
Full textAbstract:
L’océan Arctique est confronté aujourd’hui à des enjeux d’ordre souverain et environnemental. D’une part, ses États riverains revendiquent de vastes territoires maritimes. D’autre part, l’environnement de l’océan Arctique subit de multiples atteintes. La région est notamment affectée par de nombreux polluants. Puis, elle subit également de plein fouet les effets néfastes du réchauffement climatique. Le but de cette étude est de déterminer le statut juridique de l’océan Arctique au travers de ces différentes questions. Plus précisément, cette étude a pour objet l’identification, l’analyse et l’interprétation des régimes régionaux et internationaux applicables, et des problématiques de droit international s’y rapportant, afin d’appréhender le statut juridique de l’océan Arctique dans sa globalité et de déterminer sa capacité à faire face auxdits enjeux et à évoluer dans le cadre d’une coopération et d’une gouvernance interétatiques en constant développementThe Arctic Ocean is facing environmental and territorial challenges. On one hand, the coastal states are claiming vast marine territories. On the other hand, the Arctic Ocean environment suffers from many damages. In particular, the region is affected by a lot of pollutants. Then, the region also bears the brunt of the harmful effects of climate change. This study aims to determinate the legal status of the Arctic Ocean through these different issues. More precisely, this study aims to identify, to analyse and to interpret the regional and international legal regimes which apply to the Arctic Ocean, and their legal issues, in order to consider the legal status of the Arctic Ocean as a whole and to determinate its capacity to deal with environmental and territorial challenges, and to progress in the context of an intergovernmental governance and cooperation in constant development
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Duarte, Rubens Tadeu Delgado. "Micro-organismos em ambientes criogênicos: gelo glacial, solos expostos por recuo de geleiras, e permafrost polares." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-07102010-153139/.
Full textAbstract:
O efeito de alterações climáticas sobre os micro-organismos ainda é incerto, pois pouco se conhece sobre as espécies que habitam regiões extremas como o gelo, solo antártico, e o solo permanentemente congelado (permafrost). O permafrost tem como característica a preservação de material biológico por milhões de anos, servindo como fonte para estudos de evolução e biogeografia de micro-organismos. O objetivo deste trabalho foi estudar a diversidade microbiana em amostras de gelo, solo exposto por recuo de geleira e permafrost polares, e a diversidade funcional do gene alcano monoxigenase (alk). Métodos independentes de cultivo baseados no gene 16S rRNA foram utilizados, como DGGE, clonagem e pirossequenciamento. As geleiras da Ilha Rei George (Península Antártica) e do Pólo Sul Geográfico possuem cerca de 3.104 cél./mL e são compostas por micro-organismos diferentes, com predominância dos Filos Proteobacteria, Actinobacteria, Firmicutes e Cyanobacteria, muitos dos quais já descritos em outros ambientes criogênicos. O solo em frente à geleira Baranowski apresenta uma estrutura de comunidade diferente do gelo. O solo exposto por recuo de geleira apresenta uma sucessão ecológica, com predominância de heterotróficas durante todo o processo. Fixadores de nitrogênio no solo foram compostos por cianobactérias no início, e por Rhodopseudomonas e Rhodobacter no final da sucessão. Estes resultados foram melhor observados com o pirossequenciamento. As mudanças observadas podem estar relacionadas ao aumento de K, Mg+, NH4+, NO3- e/ou CO2 detectados após 15-20 anos de exposição do solo. A comunidade de permafrosts varia com o local e a idade de congelamento (de 5.000 a 8 milhões de anos). O gene alkM foi detectado em permafrosts do Ártico com 3 milhões de anos, e o gene alkB em amostras do Ártico com 15.000 e 120.000 anos, e em solos modernos da Antártica. Alguns clones indicam que podem representar novos genes para alcano monoxigenases. As contribuições deste projeto abrangem os objetivos do Ano Polar Internacional (IPY 2007-2009), sobretudo na avaliação da ecologia microbiana da Antártica.The effect of climate changes on microorganisms is still unclear, because little is known about the species that inhabit the extreme regions as the glacial ice, antarctic soils and the permanently frozen soil (permafrost). The permafrost is able to preserve the sedimented biological materials by thousands or even millions of years, being an important source for microbiological studies. The objective was to study the microbial diversity in cryogenic samples: glacial ice, soil exposed by glacial retreat and polar permafrosts, as well as to study the functional diversity of alkane monooxygenase genes (alk) in the permafrost. Cultivationindependent methods based on the 16S rRNA gene were used, as DGGE, clone library and 454 Pyrosequencing. Analysis of the King George Island (Antarctic Peninsula) glaciers and the South Pole ice revealed about 3x104 cells/mL each, and different micro-organisms were detected, predominantly members from Proteobacteria, Actinobacteria, Firmicutes and Cyanobacteria, many of which already described in other cryogenic environments. The soil in front of the Baranowski Glacier has a different community structure compared with the ice. Soils exposed by glacier retreat revealed an ecological succession, and heterotrophic bacteria occurred all through the process. Nitrogen-fixing populations were composed by cyanobacteria at the early stages, and shifted to Rhodopseudomonas and Rhodobacter in the older soils. The observed changes may be related to an increase of K, Mg+, NH4 +, NO3- and/or CO2, detected after 15-20 years of soil exposure. The community of permafrosts varies by location and age (5,000 - 8 millions of years). The alkM gene was detected in old Arctic permafrosts (3 millions of years), while alkB genes were found on Arctic samples from 15,000 to 120,000 years, and in Antarctic modern soils. Some of these clones may represent new alk genes. The contributions of this project covers the goals of the International Polar Year (IPY 2007-2009), particularly in assessing the microbial ecology of Antarctica.
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Shala, Enise, and Caroline Svanholm. "Thermodynamics of the Subsurface of Glaciers with Insights from Lomonosovfonna Ice Field at Svalbard." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-351658.
Full textAbstract:
Glaciers are important components of the Earth's environment and are mainly found in polar and high elevation areas. They are crucial for understanding the past, ongoing and upcoming environmental changes, relevant for fresh water supply, logistical and recreational purposes. Subsurface temperature of glaciers is an important parameter heavily influencing the fluxes of mass and energy. The project focuses on how the temperature changes inside glaciers and which factors contribute to the change. Thermal conduction is one of the key processes controlling the thermodynamics of glaciers. This defines how well heat is transferred inside glaciers and how well the temperature propagates. The process of heat conduction at Lomonosovfonna ice field, Svalbard, is described using numerical simulations constrained by measured initial and boundary conditions. Simulated subsurface temperature is in line with measurements before the onset of melt in summer. After that deviations increase as the used model does not consider the process of melt water refreezing. This makes the simulation only partially successful.Glaciärer är viktiga komponenter i jordens omgivning och återfinns främst i polarområden och områden på hög höjd. De är viktiga för att förstå tidigare, pågående och kommande miljöförändringar, relevanta för färskvattenförsörjning, logistiska och återskapande ändamål. Temperaturen inom glaciärer är en viktig parameter som påverkar flödena av massa och energi. Projektet fokuserar på hur temperaturen förändras inom glaciärer och vilka faktorer som bidrar till förändringen. Värmeledning är en av nyckelprocesserna som kontrollerar termodynamiken hos glaciärer. Detta definierar hur väl värme förflyttas inom glaciärer och hur väl temperaturen sprider sig. Värmeledningsprocessen på isfältet Lomonosovfonna, Svalbard, beskrivs med hjälp av numeriska simuleringar begränsade av uppmätta initial- och gränsförhållanden. Simulering av temperaturen under ytan stämmer överens med mätningarna före smältningen på sommaren. Därefter ökar avvikelsen, eftersom modellen som använts inte tar hänsyn till processen av återfrysning av smältvatten. Detta gör att simuleringen endast är delvist lyckad.
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Wiklund, Sara. "Long-term glacier mass balance of Nordenskiöldbreen, Svalbard." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-295789.
Full textAbstract:
The global warming that’s taking place have an impact over the Earth and the glaciers on Svalbard are undergoing rapid changes as a result. The annual air temperature has been rising on Svalbard since the early 1900’s and in a climate projection expected temperatures continue to rise. The glacial mass balance is important for monitoring glacier response to climate change. In this study the mass balance of Nordenskiöldbreen from 1957 to 2016 is modelled with a temperature-index model. The meteorological data used in the model, precipitation and air temperature, has been measured at a weather station located in Longyearbyen since 1957. The long simulation run makes trends in mass balance, precipitation and air temperature apparent. The mass balance can also be correlated to the temperature and precipitation, which provide important information on how these affect the behavior of glaciers. The results obtained can be used to predict how glaciers change in the future with climate change. In the simulation Nordenskiöldbreen’s mass balance has a negative trend, precipitation doesn’t have any trend and air temperature has a positive trend. The long-term mass balance is controlled by air temperature and the short-term interannual mass balance is caused by precipitation fluctuations.Den globala uppvärmningen som sker just nu har en påverkan över hela jorden och glaciärer på Svalbard genomgår snabba förändringar som följd. På Svalbard har den årliga medeltemperaturen stigit sedan början av 1900-talet och i en klimatprojicering förväntas temperaturen att fortsätta stiga. Den glaciala massbalansen är viktig för att övervaka glaciärers respons till klimatförändringar. I detta arbete modelleras Nordenskiöldbreens massbalans från 1957 till 2016 med hjälp av en temperaturindex modell. Den meteorologiska data som används i modellen, nederbörd och temperatur, har mätts vid en väderstation i Longyearbyen sedan 1957. Med den långa tidsperioden i modellen blir långsiktiga trender i massbalans, nederbörd och temperatur tydliga. Massbalansen kan även korreleras mot temperatur och nederbörd, vilket ger viktig information om hur dessa påverkar glaciärers beteenden. De resultat som framkommer kan användas för att förutspå hur glaciärer förändras i framtiden med en klimatändring. I simuleringen har Nordenskiöldbreens massbalans en negativ trend, nederbörd har ingen trend och temperatur har en positiv trend. Det är temperatur som styr den långsiktiga massbalansen och den kortsiktiga mellanårs-massbalansen styrs av nederbörds fluktuationer.
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Ott, Florian [Verfasser], and Achim [Akademischer Betreuer] Brauer. "Late Glacial and Holocene climate and environmental evolution in the southern Baltic lowlands derived from varved lake sediments / Florian Ott ; Betreuer: Achim Brauer." Potsdam : Universität Potsdam, 2018. http://d-nb.info/1218403853/34.
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Seagren, A. G. "The nature of solute acquisition and suspended sediment dynamics in channelised subglacial weathering environments, Haut Glacier D'Arolla, Valais, Switzerland." Thesis, Aberystwyth University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391247.
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Landin, Nils Charles. "Acid sulfate weathering in natural glacially derived soils of north western Indiana and the environmental implications." Thesis, Purdue University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10159495.
Full textAbstract:
Northwestern Indiana has land surfaces and soils that are around 15,000 years old, resulting from sediments deposited from the Wisconsinan Glaciation during the late Pleistocene period. These geologically young soils exhibit depletion of base cations and low pH's (near 4.0) which are chemically similar to much older and more intensely weathered soils. We hypothesize that FeS2 (iron pyrite) within the shale fragments of the glacial deposits was oxidized upon exposure of oxygen near the earth's surface and resulted in naturally occurring acid sulfate weathering. To test our hypothesis, we isolated the area with ArcGIS, collected clast samples from gravel pits, utilized historic soils databases, and analyzed samples with X-ray diffraction to determine if associated properties and soil minerals would support acid sulfate weathering as the cause of the current soil chemical properties. Soil samples and glacial outwash cobble-sized clasts were collected and X-ray diffraction was used to determine the presence of pyrite or of pyrite weathering products jarosite and gypsum. Existing soil databases and lab data were examined to obtain further details of the occurrence of the potential acid sulfate weathering. A review of the geologic literature was also conducted to put the acid sulfate weathering processes into a landscape perspective and geologic context. The clast samples and some soil samples indicated the presence of jarosite and gypsum which are commonly associated with acid sulfate weathering. This research also found that ultic soil properties and low pH soils were associated with sandy glacial outwash and this information was displayed spatially. The sandy outwash has a lower CEC and lower buffering capacity when compared to nearby higher clayey glacial till. There was inferential evidence of acid sulfate weathering in calcareous glacial which is illustrated by iron oxide pseudomorphs. The lack of initial pyritic shale combined with the neutralizing potential for the calcareous till prevented these soils from developing ultic properties and low pH's. Additionally, this research assessed the potential for naturally occurring arsenic in the soils. Elevated arsenic levels were found in soils that occurred in the lowest part of the landscape. Understanding the process of naturally occurring acid sulfate weathering and associated elevated arsenic within this landscape will provide more information on use and management of these areas.