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  • 251. Graham, Alastair G. C.
    et al.
    Dutrieux, Pierre
    Vaughan, David G.
    Nitsche, Frank O.
    Gyllencreutz, Richard
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Greenwood, Sarah L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Larter, Robert D.
    Jenkins, Adrian
    Seabed corrugations beneath an Antarctic ice shelf revealed by autonomous underwater vehicle survey: Origin and implications for the history of Pine Island Glacier2013In: Journal of Geophysical Research: Earth Surface, ISSN 2169-9011, Vol. 118, no 3, p. 1356-1366Article in journal (Refereed)
    Abstract [en]

    [1] Ice shelves are critical features in the debate about West Antarctic ice sheet change and sea level rise, both because they limit ice discharge and because they are sensitive to change in the surrounding ocean. The Pine Island Glacier ice shelf has been thinning rapidly since at least the early 1990s, which has caused its trunk to accelerate and retreat. Although the ice shelf front has remained stable for the past six decades, past periods of ice shelf collapse have been inferred from relict seabed “corrugations” (corrugated ridges), preserved 340 km from the glacier in Pine Island Trough. Here we present high-resolution bathymetry gathered by an autonomous underwater vehicle operating beneath an Antarctic ice shelf, which provides evidence of long-term change in Pine Island Glacier. Corrugations and ploughmarks on a sub-ice shelf ridge that was a former grounding line closely resemble those observed offshore, interpreted previously as the result of iceberg grounding. The same interpretation here would indicate a significantly reduced ice shelf extent within the last 11 kyr, implying Holocene glacier retreat beyond present limits, or a past tidewater glacier regime different from today. The alternative, that corrugations were not formed in open water, would question ice shelf collapse events interpreted from the geological record, revealing detail of another bed-shaping process occurring at glacier margins. We assess hypotheses for corrugation formation and suggest periodic grounding of ice shelf keels during glacier unpinning as a viable origin. This interpretation requires neither loss of the ice shelf nor glacier retreat and is consistent with a “stable” grounding-line configuration throughout the Holocene.

  • 252.
    Graham, Robert M.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The role of Southern Ocean fronts in the global climate system2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The location of fronts has a direct influence on both the physical and biological processes in the Southern Ocean. However, until recently fronts have been poorly resolved by available data and climate models. In this thesis we utilise a combination of high resolution satellite data, model output and ARGO data to improve our basic understanding of fronts.

    A method is derived whereby fronts are identified as local maxima in sea surface height gradients. In this way fronts are defined locally as jets, rather than continuous-circumpolar water mass boundaries. A new climatology of Southern Ocean fronts is presented. This climatology reveals a new interpretation of the Subtropical Front. The currents associated with the Subtropical Front correspond to the western boundary current extensions from each basin, and we name these the Dynamical Subtropical Front. Previous studies have instead suggested that the Subtropical Front is a continuous feature across the Southern Ocean associated with the super gyre boundary.

    A comprehensive assessment of the relationship between front locations and wind stress is conducted. Firstly, the response of fronts to a southward shift in the westerly winds is tested using output from a 100 year climate change simulation on a high resolution coupled model. It is shown that there was no change in the location of fronts within the Antarctic Circumpolar Current as a result of a 1.3° southward shift in the westerly winds. Secondly, it is shown that the climatological position of the Subtropical Front is 5-10° north of the zero wind stress curl line, despite many studies assuming that the location of the Subtropical Front is determined by the zero wind stress curl.

    Finally, we show that the nutrient supply at ocean fronts is primarily due to horizontal advection and not upwelling. Nutrients from coastal regions are entrained into western boundary currents and advected into the Southern Ocean along the Dynamical Subtropical Front. 

  • 253.
    Graham, Robert M.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    De Boer, Agatha M.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Kohfeld, Karen E.
    Schlosser, Christian
    Identifying sources and transport pathways of iron in the Southern OceanIn: Deep Sea Research Part I: Oceanographic Research Papers, ISSN 0967-0637, E-ISSN 1879-0119Article in journal (Refereed)
    Abstract [en]

    Over large regions of the global ocean primary productivity is limited by the availability of dissolved iron. Changes in the supply of iron to these regions could have major impacts on primary productivity and the carbon cycle. One of the largest sources of dissolved iron to the ocean is thought to be from shelf sediments, and this source is often parameterized in biogeochemical models as a depth dependent iron flux through the seafloor. Using the knowledge that Southern Ocean surface waters are iron limited, we infer source regions of iron to the Southern Ocean by identifying where the most intense chlorophyll blooms develop. We further derive surface current patterns from satellite sea surface height fields to assess the role of the ocean circulation in transporting iron away from these source regions. We find a tight relationship between satellite chlorophyll concentrations and sea surface height. Large chlorophyll blooms develop on the shelf and where the western boundary currents detach from the continental shelves and turn eastward into the Southern Ocean. This is likely due to shelf supplied iron becoming entrained into western boundary currents and advected into the Southern Ocean along the Dynamical Subtropical Front. The most intense chlorophyll blooms are located along coastal margins of islands and continents. Blooms do not develop over submerged seamounts or plateaus in the open ocean. This suggests that shelf sediments in coastal regions act as large bioavailable iron sources to the Southern Ocean. We recommend that a more accurate method of parameterizing the shelf sediment iron flux could be to prescribe this flux only through grid cells neighboring coastlines. Finally, we hypothesize how changes in sea level during glacial-interglacial cycles may have altered the distribution of shelf sediment iron sources in the Southern Ocean and helped to drive export production anomalies in the Sub-Antarctic Zone.

  • 254.
    Granath, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Baltzer, Jennifer L.
    Biology Department, Wilfrid Laurier University, Waterloo, Canada.
    Bengtsson, Fia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Boncek, Nicholas
    Department of Biological Sciences, Union College, Schenectady, NY, USA.
    Bragazza, Luca
    Department of Life Science and Biotechnologies, University of Ferrara, Ferrara, Italy; Swiss Federal Institute for Forest, Snow and Landscape Research, WSL Site Lausanne, Station 2, Lausanne, Switzerland; Ecole Polytechnique Fédérale de Lausanne EPFL, School of Architecture, Civil and Environmental Engineering ENAC, Laboratory of ecological systems ECOS, Station 2, Lausanne, Switzerland.
    Bu, Zhao-Jun
    Institute for Peat and Mire Research, Northeast Normal University, State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Changchun, China; Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Changchun, China.
    Caporn, Simon J. M.
    School of Science and the Environment, Division of Biology and Conservation Ecology, Manchester Metropolitan University, Manchester, UK.
    Dorrepaal, Ellen
    Climate Impacts Research Centre, Dept. of Ecology and Environmental Science, Umeå University, Abisko, Sweden.
    Galanina, Olga
    Institute of Earth Sciences, St. Petersburg State University, St. Petersburg, Russia; Komarov Botanical Institute Russian Academy of Sciences, St. Petersburg, Russia.
    Galka, Mariusz
    Laboratory of Wetland Ecology and Monitoring & Department of Biogeography and Paleoecology, Adam Mickiewicz University in Poznan, Poznan, Polen.
    Ganeva, Anna
    Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria.
    Gillikin, David P.
    Department of Geology, Union College, Schenectady, NY, USA.
    Goia, Irina
    Babe ̧s-Bolyai University, Faculty of Biology and Geology, Department of Taxonomy and Ecology, Cluj Napoca, Romania.
    Goncharova, Nadezhda
    Institute of Biology of Komi Scientific Centre of the Ural Branch of the Russian Academy of Science, Syktyvkar, Russia.
    Hajek, Michal
    Masaryk Univ, Fac Sci, Dept Bot & Zool, Brno, Czech Republic.
    Haraguchi, Akira
    Univ Kitakyushu, Dept Biol, Kitakyushu, Fukuoka, Japan.
    Harris, Lorna I.
    McGill Univ, Dept Geog, Montreal, Canada.
    Humphreys, Elyn
    Carleton Univ, Dept Geog & Environm Studies, Ottawa, Canada.
    Jirousek, Martin
    Masaryk Univ, Fac Sci, Dept Bot & Zool, Brno, Czech Republic; Mendel Univ Brno, Fac AgriSci, Dept Plant Biol, Brno, Czech Republic.
    Kajukalo, Katarzyna
    Adam Mickiewicz Univ, Lab Wetland Ecol & Monitoring, Poznan, Poland; Adam Mickiewicz Univ, Dept Biogeog & Paleoecol, Poznan, Poland.
    Karofeld, Edgar
    Univ Tartu, Inst Ecol & Earth Sci, Tartu, Estonia.
    Koronatova, Natalia G.
    Russian Acad Sci, Siberian Branch, Inst Soil Sci & Agrochem, Lab Biogeocenol, Novosibirsk, Russia.
    Kosykh, Natalia P.
    Russian Acad Sci, Siberian Branch, Inst Soil Sci & Agrochem, Lab Biogeocenol, Novosibirsk, Russia.
    Lamentowicz, Mariusz
    Adam Mickiewicz Univ, Lab Wetland Ecol & Monitoring, Poznan, Poland; Adam Mickiewicz Univ, Dept Biogeog & Paleoecol, Poznan, Poland.
    Lapshina, Elena
    Yugra State Univ, Khanty Mansiysk, Russia.
    Limpens, Juul
    Wageningen Univ, Plant Ecol & Nat Conservat Grp, Wageningen, Netherlands.
    Linkosalmi, Maiju
    Finnish Meteorol Inst, Helsinki, Finland.
    Ma, Jin-Ze
    Northeast Normal Univ, State Environm Protect Key Lab Wetland Ecol & Veg, Inst Peat & Mire Res, Changchun, Jilin, Peoples R China; Jilin Prov Key Lab Wetland Ecol Proc & Environm C, Changchun, Jilin, Peoples R China.
    Mauritz, Marguerite
    No Arizona Univ, Dept Biol Sci, Ctr Ecosyst Sci & Soc Ecoss, Flagstaff, USA.
    Munir, Tariq M.
    Univ Calgary, Dept Geog, Calgary, Canada; St Marys Univ, Dept Geol, Calgary, Canada.
    Natali, Susan M.
    Woods Hole Res Ctr, Falmouth, USA.
    Natcheva, Rayna
    Bulgarian Acad Sci, Inst Biodivers & Ecosyst Res, Sofia, Bulgaria.
    Noskova, Maria
    Russian Acad Sci, Komarov Bot Inst, St Petersburg, Russia.
    Payne, Richard J.
    Univ York, Environm, York, N Yorkshire, England; Penza State Univ, Penza, Russia.
    Pilkington, Kyle
    Union Coll, Dept Biol Sci, Schenectady, NY USA.
    Robinson, Sean
    SUNY Coll Oneonta, Dept Biol, Oneonta, NY USA.
    Robroek, Bjorn J. M.
    Univ Southampton, Biol Sci, Southampton, Hants, England.
    Rochefort, Line
    Laval Univ, Dept Plant Sci, Quebec City, PQ, Canada; Laval Univ, Ctr Northern Studies, Quebec City, PQ, Canada.
    Singer, David
    Univ Neuchatel, Inst Biol, Lab Soil Biodivers, Neuchatel, Switzerland; Univ Sao Paulo, Inst Biosci, Dept Zool, Sao Paulo, Brazil.
    Stenoien, Hans K.
    Norwegian Univ Sci & Technol, NTNU Univ Museum, Trondheim, Norway.
    Tuittila, Eeva-Stiina
    Univ Eastern Finland, Sch Forest Sci, Peatland & Soil Ecol Grp, Joensuu, Finland.
    Vellak, Kai
    Univ Tartu, Inst Ecol & Earth Sci, Tartu, Estonia.
    Verheyden, Anouk
    Union Coll, Dept Geol, Schenectady, NY USA.
    Waddington, James Michael
    McMaster Univ, Sch Geog & Earth Sci, Hamilton, Canada.
    Rice, Steven K.
    Union Coll, Dept Biol Sci, Schenectady, NY USA.
    Environmental and taxonomic controls of carbon and oxygen stable isotope composition in Sphagnum across broad climatic and geographic ranges2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 16, p. 5189-5202Article in journal (Refereed)
    Abstract [en]

    Rain-fed peatlands are dominated by peat mosses (Sphagnum sp.), which for their growth depend on nutrients, water and CO2 uptake from the atmosphere. As the isotopic composition of carbon (C-12(,)13) and oxygen (O-16(,)18) of these Sphagnum mosses are affected by environmental conditions, Sphagnum tissue accumulated in peat constitutes a potential long-term archive that can be used for climate reconstruction. However, there is inadequate understanding of how isotope values are influenced by environmental conditions, which restricts their current use as environmental and palaeoenvironmental indicators. Here we tested (i) to what extent C and O isotopic variation in living tissue of Sphagnum is speciesspecific and associated with local hydrological gradients, climatic gradients (evapotranspiration, temperature, precipitation) and elevation; (ii) whether the C isotopic signature can be a proxy for net primary productivity (NPP) of Sphagnum; and (iii) to what extent Sphagnum tissue delta O-18 tracks the delta O-18 isotope signature of precipitation. In total, we analysed 337 samples from 93 sites across North America and Eurasia us ing two important peat-forming Sphagnum species (S. magellanicum, S. fuscum) common to the Holarctic realm. There were differences in delta C-13 values between species. For S. magellanicum delta C-13 decreased with increasing height above the water table (HWT, R-2 = 17 %) and was positively correlated to productivity (R-2 = 7 %). Together these two variables explained 46 % of the between-site variation in delta C-13 values. For S. fuscum, productivity was the only significant predictor of delta C-13 but had low explanatory power (total R-2 = 6 %). For delta O-18 values, approximately 90 % of the variation was found between sites. Globally modelled annual delta O-18 values in precipitation explained 69 % of the between-site variation in tissue delta O-18. S. magellanicum showed lower delta O-18 enrichment than S. fuscum (-0.83 %0 lower). Elevation and climatic variables were weak predictors of tissue delta O-18 values after controlling for delta O-18 values of the precipitation. To summarize, our study provides evidence for (a) good predictability of tissue delta O-18 values from modelled annual delta O-18 values in precipitation, and (b) the possibility of relating tissue delta C-13 values to HWT and NPP, but this appears to be species-dependent. These results suggest that isotope composition can be used on a large scale for climatic reconstructions but that such models should be species-specific.

  • 255.
    Granit, Jakob
    Stockholm International Water Institute (SIWI).
    Identifying Business Models for Transboundary River Basin Institutions2010In: Transboundary Water Management: Principles and Practise / [ed] Anton Earle, Anders Jägerskog and Joakim Öjendal, London: Earthscan , 2010, p. 143-154Chapter in book (Refereed)
  • 256.
    Granit, Jakob
    Stockholm International Water Institute (SIWI).
    Reconsidering Integrated Water Resources Management: Promoting Economic Growth and Tackling Environmental Stress2011In: Coping with Global Environmental Change, Disasters and Security: Threats, Challenges, Vulnerabilities and Risks / [ed] Brauch, H.G., Spring, U. O., Mesjaz, C., Grin, J.,Kamere – Mbote, P., Chourou. B., Dunay, P. & Birkman, J., Berlin, Heidelberg: Springer, 2011, p. 947-955Chapter in book (Refereed)
    Abstract [en]

    Integrated Water Resources Management (IWRM) is today widely advocated by natural resources managers and the scientific community as the preferred approach to manage water. IWRM stresses the river basin as the single management unit and the integration of freshwater using sectors and stakeholders across society.

  • 257.
    Granit, Jakob J.
    et al.
    Stockholm International Water Institute (SIWI).
    King, R. Michael
    Noël, Raymond
    Strategic Environmental Assessment as a tool to Develop Power in Transboundary Water Basin Settings2011In: International Journal of Social Ecology and Sustainable Development, ISSN 1947-8402, Vol. 2, no 4, p. 1-11Article in journal (Refereed)
    Abstract [en]

    This paper proposes a generic consultative process for undertaking Strategic Environmental Assessments (SEA) in a transboundary river basin context to bring up front environmental and social issues of major development programs into the transboundary planning, project development and investment finance processes. The paper demonstrates through an analysis of two case studies from the Nile Basin in East and North Africa how an SEA approach with a focus on hydropower development is a transparent pre-investment tool that allows for consensus building in support of transboundary and regional strategic decision making and integration. Further, it demonstrates how an SEA can guide public and private sector investors seeking to develop the power sector in general and hydropower options in particular by allowing for a first level understanding of challenges and opportunities of power development and the development scenarios preferred by riparian governments.

  • 258.
    Greenwood, Sarah L.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Gyllencreutz, Richard
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jakobsson, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Anderson, John B.
    Ice-flow switching and East/West Antarctic Ice Sheet roles in glaciation of the western Ross Sea2012In: Geological Society of America Bulletin, ISSN 0016-7606, E-ISSN 1943-2674, Vol. 124, no 11-12, p. 1736-1749Article in journal (Refereed)
    Abstract [en]

    The long-term behavior of the East and West Antarctic Ice Sheets, and their respective responses to forcing provide essential context for assessment of modern dynamic changes in ice-flow regimes and ice-sheet and shelf margins. The western Ross Sea discharges ice from both the East and West Antarctic Ice Sheets, and the paleoglacial record from this region is therefore valuable in unraveling their long-term behavior. New, high-resolution multibeam bathymetric data reveal snapshots of well-preserved glacial landforms on the seafloor around Ross Island and McMurdo Sound. Glacial lineations, grounding zone wedges, draped recessional moraines, and meltwater channels record a series of different ice-flow events in the region, contradictions between which require major phases of ice-flow reorganization. From the glacial geomorphology, we reconstruct a four-stage model of ice-flow evolution for the last glacial cycle, consisting of: (1) northeastward flow into the Ross Sea from McMurdo Sound; (2) westward flow from the Ross Sea, around Ross Island, and onto the Victoria Land coast and coastal seafloor trough; (3) a deglacial phase of ice-sheet thinning, minor shifts in flow, and grounding line retreat into McMurdo Sound; and (4) grounding line pinning on Ross Island during regional retreat, uncoupling of a remnant Ross Island ice cap, and local oscillation of Victoria Land outlet glaciers. We find that East Antarctic Ice Sheet ice discharge had a strong influence on ice-flow geometry in this part of the Ross Sea during the last glacial stage, but that it was not necessarily in phase with the behavior of the West Antarctic Ice Sheet. It is similarly evident that the ice streams that drained the Ross Sea over the continental shelf at the Last Glacial Maximum did not all operate synchronously, and exerted different drawdown power at different times. Finally, we conclude that Ross Island acts as an important pinning point in the Ross Sea ice-sheet-shelf system, stabilizing grounding line retreat and encouraging lasting ice-shelf development.

  • 259. Grimm, Guido
    et al.
    Bouchal, Johannes M.
    Swedish Museum of Natural History, Department of Paleobiology.
    Denk, Thomas
    Swedish Museum of Natural History, Department of Paleobiology.
    Potts, Alastair
    Fables and foibles: A critical analysis of the Palaeoflora database and the Coexistence Approach for palaeoclimate reconstruction2016In: Review of Palaeobotany and Palynology, ISSN 0034-6667, E-ISSN 1879-0615, Vol. 233, p. 216-235Article in journal (Refereed)
    Abstract [en]

    The ‘Coexistence Approach’ is amutual climate range (MCR) technique combinedwith the nearest-living relative (NLR) concept. It has been widely used for palaeoclimate reconstructions based on Eurasian plant fossil assemblages; most of them palynofloras (studied using light microscopy). The results have been surprisingly uniform, typically converging to subtropical, per-humid or monsoonal conditions. Studies based on the Coexistence Approach have had a marked impact in literature, generating over 10,000 citations thus far. However, recent studies have pointed out inherent theoretical and practical problems entangled in the application of this widely used method. But so far little is known how results generated by the Coexistence Approach are affected by subjective errors, data errors, and violations of the basic assumptions. The majority of Coexistence Approach studies make use of the Palaeoflora database (the combination of which will be abbreviated to CA + PF). Testing results produced by CA + PF studies has been hindered by the general unavailability of the contents in the underlying Palaeoflora database; two exceptions are the mean-annual temperature tolerances and lists of assigned associations between fossils and nearest-living relatives. Using a recently published study on the Eocene of China,which provides the first and only insight into the data structure of the Palaeoflora database,we compare the theory and practice of Coexistence Approach using the Palaeoflora database (CA+PF).We show that CA+PF is riddled by association and climate data error.We reveal flaws in the application of the Coexistence Approach,which is often in stark contrast to the theory of the method. We show that CA + PF is highly vulnerable against numerous sources of errors, mainly because it lacks safeguards that could identify unreliable data. We demonstrate that the CA+PF produces coherent, pseudo-precise results even for artificially generated, randomplant assemblages. AlternativeMCR-NLR methods can surpass the most imminent deficits of the Coexistence Approach, and may be used as a stop-gap until more accurate bioclimatic and distribution data on potential Eurasian NLRs, and theoretically and statistically robust methods will become available. Finally, general guidelines are provided for the future application of methods using the mutual climatic range with nearest living relatives approach when reconstructing climate from plant fossil assemblages.

  • 260. Grímsson, F.
    Meller, Barbara (Contributor)
    Bouchal, Johannes M. (Contributor)
    Swedish Museum of Natural History, Department of Paleobiology.
    Grimm, Guido (Contributor)
    Combined LM and SEM study of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin, Austria: Part III. Magnoliophyta 1 – Magnoliales to Fabales2015In: Grana, ISSN 0017-3134, E-ISSN 1651-2049, Vol. 54, p. 85-128Article in journal (Refereed)
    Abstract [en]

    Previous studies on the palynoflora from the Lavanttal Basin show that it contains a rich

    assemblage of spores and gymnosperm pollen. Present and ongoing investigations of

    dispersed angiosperm pollen suggest a high diversity within this group, and due to the

    excellent preservation of the material some rare pollen types are recognized. The Magnoliales

    to Fabales pollen record documented here contains 30 different taxa. Only a few pollen types

    are assigned to Magnoliids (four taxa); these are rare in the pollen record. Similarly, the

    Commelinids comprise five taxa and are also rare. Most of the angiosperm pollen originate

    from Eudicots, 21 taxa. Of the angiosperm taxa documented here, Magnolia , Carex ,

    Ranunculaceae, Platanus , Trochodendron , Buxus , Cercidiphyllum , Daphniphyllum ,

    Distylium , Fortunearia , Parrotia , Parthenocissus , Vitis , Euphorbia , Salix , and

    Papilionoideae are recorded for the first time from the Lavanttal Basin. This also includes the

    first fossil pollen record of Trochodendron  worldwide and the first reliable pollen record of

    Daphniphyllum . Several of the taxa described here had a wide Northern Hemispheric

    distribution from Eocene until the end of the Miocene. Also, key relatives of the fossil taxa

    are presently confined to humid warm-temperate environments, suggesting a very mild

    climate during the middle Miocene (Sarmatian) of the Lavanttal area. Some of the taxa

    encountered also support previous observations that the sediments of the Lavanttal Basin

    accumulated in a lowland wetland environment. This is based on pollen from aquatic taxa

    thriving in lakes, streams and swamps, and pollen of terrestrial plant taxa occupying margins

    of lakes and streams, backswamps, floodplains, river plains, and hummocks. Other 

     angiosperm pollen clearly originate from plants thriving on drier substrates, reflecting various

    vegetation units of the mixed evergreen/deciduous broad-leaved/conifer forests surrounding

    the wetland basin.

  • 261. Grímsson, F.
    Bouchal, Johannes M. (Contributor)
    Swedish Museum of Natural History, Department of Paleobiology.
    Meller, Barbara (Contributor)
    Zetter, Reinhard (Contributor)
    Combined LM and SEM study of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin, Austria: part IV. Magnoliophyta 2 – Fagales to RosalesIn: Grana, ISSN 0017-3134, E-ISSN 1651-2049Article in journal (Refereed)
    Abstract [en]

    An ongoing investigation of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin continues to show that it contains an extremely rich assemblage of angiosperm taxa. The Fagales to Rosales pollen record documented here contains 34 different taxa belonging to the Betulaceae (Alnus, Betula, Carpinus, Corylus, Ostrya), Fagaceae (Castanea, Fagus, Quercus Groups Cerris, Ilex, Cyclobalanopsis, Quercus/Lobatae), Juglandaceae (Engelhardioideae, Carya, Juglans, Pterocarya), Myricaceae (Morrella vel Myrica), Cannabaceae (Celtis), Elaeagnaceae (Elaeagnus), Rhamnaceae, Rosaceae (Prunus) and Ulmaceae (Cedrelospermum, Ulmus, Zelkova). Two of the pollen types represent extinct genera, Trigonobalanopsis and Cedrelospermum, and are also reported for the first time from the Lavanttal Basin along with pollen of Rhamnaceae and Prunus. The different types of Quercus pollen are now affiliated with Groups Cerris, Cyclobalanopsis, Ilex and Quercus/Lobatae based on sculpturing elements observed using scanning electron microscopy (SEM). Köppen signatures of potential modern analogues of the fossil Fagales and Rosales suggest a subtropical (Cfa, Cwa) climate at lower elevation and subsequent subtropical to temperate climate with altitudinal succession (Cfa→Cfb/Dfa→Dfb; Cwa→Cwb→Dwb) in the Lavanttal area during accumulation of the palynoflora. Most of the fossil taxa have potential modern analogues that can be grouped as nemoral and/or merido-nemoral vegetation elements, and the diversity of Fagales indicates a varying landscape with a high variety of niches.

  • 262. Grímsson, F.
    et al.
    Bouchal, Johannes M.
    Swedish Museum of Natural History, Department of Paleobiology.
    Grimm, Guido
    Zetter, Reinhard
    Evaluating the mid Miocene paleoclimate of Lower Carinthia (Austria) based on high resolution palynological studies from the Lavanttal Basin2016Conference paper (Other academic)
    Abstract [en]

    Köppen signatures (Denk et al. 2013, Grímsson et al. 2015) can be used to generalize the climatic niche occupied by potential modern analogues (PMA) of fossil plants (here: palynological) assemblages. The Köppen climate system distinguishes climate zones by certain abiotic parameters or combinations thereof and represents them in a three letter code referring to the general climate types (first letter), the seasonal distribution of precipitation (second letter) and the seasonal distribution or general level of warmth (third letter). Based on their Köppen signatures PMAs can be categorized as arctic-alpine, boreal, nemoral, meridio-nemoral, tropical-meridional, tropical, eurytropical, and/or semihumid meridional vegetation elements (see also Denk et al. 2013, Velitzelos et al. 2014, Grímsson et al. 2015). Based on the climatic preferences of their PMAs, the Fagales and Rosales lineages present at the Lavanttal site rule out tropical (A-)climates and climates with pronounced (summer) draught (B-, Cs-, Ds-climates). The same holds for boreal/subarctic climates with short but humid summers (Cfc, Dfc, Dfd, Dwc). The Fagales are represented by 23 lineages at the Lavanttal site including genera that are today composed (predominately or exclusively) of nemoral and meridio-nemoral elements. This points to climate conditions not unlike those found today in the lowlands and adjacent mountain regions of the (south-)eastern United States, the humid-meridional region of western Eurasia (e.g. northern Italy, Black Sea region, western Caucasus), central and southern China, or Honshu (Japan). These regions are characterised by subtropical conditions at lower elevations (Cfa-, Cwa-climates) and subsequent altitudinal successions: Cfa! Cfb/Dfa! Dfb in eastern United States, western Eurasia, central China and Japan, or Cwa! Cwb! Dwb in southern China. The climax vegetation in these areas are mixed mesophytic forests and various mixed evergreen/deciduous broad-leaved forests, characteristic for the humid and semi-humid, summer-rain areas of the meridional and nemoral zone. (Co-)Dominant genera in these forests are the various members of the northern hemispheric Fagales. Important indicator taxa include Fagus , one of the most common and widespread genera in temperate, mixed mesophytic forests of North America, China and Japan, and Quercus Group Ilex, a co-dominant group in the East Asian monsoon influenced, winter-dry or fully humid southern foothills of the Himalayas and montane regions of south-western and central China. Equally informative is Corylus, and the co-occurrence of Carya , Juglans , Pterocarya  and Engelhardioideae, pinpointing towards forests as today found in south-western China and the warm subtropical parts of the southeastern United States.

  • 263.
    Gueriau, Pierre
    et al.
    Univ Paris 06, CNRS, MNHN,CR2P,UMR 7207, Univ Paris 04,Ctr Rech Paleobiodiversite & Paleoe, 57 Rue Cuvier,CP 38, F-75005 Paris, France.;Museum Natl Hist Nat, 57 Rue Cuvier,CP 38, F-75005 Paris, France.;Univ Paris Saclay, IPANEMA, CNRS, Minist Culture & Commun,USR3461, F-91192 Gif Sur Yvette, France.;Synchrotron SOLEIL, BP 48 St Aubin, F-91192 Gif Sur Yvette, France..
    Rabet, Nicolas
    Univ Paris 06, Univ Paris 04, MNHN,BOREA,UMR 7208, UCBN,CNRS,IRD,Unite Biol Organismes & Ecosyst Aqu, 57 Rue Cuvier,CP 26, F-75005 Paris, France.;Museum Natl Hist Nat, 57 Rue Cuvier,CP 26, F-75005 Paris, France..
    Clement, Gael
    Univ Paris 06, CNRS, MNHN,CR2P,UMR 7207, Univ Paris 04,Ctr Rech Paleobiodiversite & Paleoe, 57 Rue Cuvier,CP 38, F-75005 Paris, France.;Museum Natl Hist Nat, 57 Rue Cuvier,CP 38, F-75005 Paris, France..
    Lagebro, Linda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Vannier, Jean
    Univ Lyon 1, UMR CNRS 5276, Lab Geol Lyon Terre Planetes Environm LGLTPE, Geode, Campus LyonTech la Doua,2 Rue Dubois, F-69622 Villeurbanne, France..
    Briggs, Derek E. G.
    Yale Univ, Dept Geol & Geophys, POB 208109, New Haven, CT 06520 USA.;Yale Univ, Yale Peabody Museum Nat Hist, POB 208109, New Haven, CT 06520 USA..
    Charbonnier, Sylvain
    Univ Paris 06, CNRS, MNHN,CR2P,UMR 7207, Univ Paris 04,Ctr Rech Paleobiodiversite & Paleoe, 57 Rue Cuvier,CP 38, F-75005 Paris, France.;Museum Natl Hist Nat, 57 Rue Cuvier,CP 38, F-75005 Paris, France..
    Olive, Sebastien
    Royal Belgian Inst Nat Sci, Directorate Earth & Hist Life Palaeobiosphere & E, Rue Vautier 29, B-1000 Brussels, Belgium.;Univ Liege, Dept Geol, Evolut & Div Dynam Lab, B18,Allee Six Aout, B-4000 Liege, Belgium..
    Bethoux, Olivier
    Univ Paris 06, CNRS, MNHN,CR2P,UMR 7207, Univ Paris 04,Ctr Rech Paleobiodiversite & Paleoe, 57 Rue Cuvier,CP 38, F-75005 Paris, France.;Museum Natl Hist Nat, 57 Rue Cuvier,CP 38, F-75005 Paris, France..
    A 365-Million-Year-Old Freshwater Community Reveals Morphological and Ecological Stasis in Branchiopod Crustaceans2016In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 26, no 3, p. 383-390Article in journal (Refereed)
    Abstract [en]

    Branchiopod crustaceans are represented by fairy, tadpole, and clam shrimps (Anostraca, Notostraca, Laevicaudata, Spinicaudata), which typically inhabit temporary freshwater bodies, and water fleas (Cladoceromorpha), which live in all kinds of freshwater and occasionally marine environments [1, 2]. The earliest branchiopods occur in the Cambrian, where they are represented by complete body fossils from Sweden such as Rehbachiella kinnekullensis [3] and isolated mandibles preserved as small carbonaceous fossils [4-6] from Canada. The earliest known continental branchiopods are associated with hot spring environments [7] represented by the Early Devonian Rhynie Chert of Scotland (410 million years ago) and include possible stem-group or crown-group Anostraca, Notostraca, and clam shrimps or Cladoceromorpha [8-10], which differmorphologically fromtheirmodern counterparts [1, 2, 11]. Here we report the discovery of an ephemeral pool branchiopod community from the 365-million-year-old Strud locality of Belgium. It is characterized by new anostracans and spinicaudatans, closely resembling extant species, and the earliest notostracan, Strudops goldenbergi [12]. These branchiopods released resting eggs into the sediment in a manner similar to their modern representatives [1, 2]. We infer that this reproductive strategy was critical to overcoming environmental constraints such as seasonal desiccation imposed by living on land. The pioneer colonization of ephemeral freshwater pools by branchiopods in the Devonian was followed by remarkable ecological and morphological stasis that persists to the present day.

  • 264.
    Guillemette, Francois
    et al.
    Uppsala University, Sweden.
    von Wachenfeldt, Eddie
    Uppsala University, Sweden; Swedish University of Agriculture Science, Sweden.
    Kothawala, Dolly N.
    Uppsala University, Sweden.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Tranvik, Lars J.
    Uppsala University, Sweden.
    Preferential sequestration of terrestrial organic matter in boreal lake sediments2017In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, no 4, p. 863-874Article in journal (Refereed)
    Abstract [en]

    The molecular composition and origin has recently been demonstrated to play a critical role in the persistence of organic matter in lake water, but it is unclear to what degree chemical attributes and sources may also control settling and burial of organic matter in lake sediments. Here we compared the annual contribution of allochthonous and autochthonous sources to the organic matter settling in the water column and present in the sediments of 12 boreal lakes. We used the fluorescence properties and elemental composition of the organic matter to trace its origin and found a consistent pattern of increasing contribution of terrestrial compounds in the sediments as compared to the settling matter, with an annual average allochthony of similar to 87% and similar to 57%, respectively. Seasonal data revealed a predominance of in-lake-produced compounds sinking in the water column in summer. Yet only a slight concurrent decrease in the contribution of terrestrial C to lake sediments was observed during the same period, and sediment allochthony increased again to high levels in autumn. Our results reveal a preferential preservation of allochthonous matter in the sediments and highlight the role of lakes as sequesters of organic carbon primarily originating from the surrounding landscape.

  • 265.
    Guldstrand, Frank
    et al.
    Univ Oslo, Dept Geosci, NJORD Ctr, PGP, Oslo, Norway.
    Galland, Olivier
    Univ Oslo, Dept Geosci, NJORD Ctr, PGP, Oslo, Norway.
    Hallot, Erwan
    Univ Rennes, CNRS, UMR 6118, Geosci Rennes, Rennes, France.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Experimental Constraints on Forecasting the Location of Volcanic Eruptions from Pre-eruptive Surface Deformation2018In: Frontiers in earth science, ISSN 2296-6463, Vol. 6, article id UNSP 7Article in journal (Refereed)
    Abstract [en]

    Volcanic eruptions pose a threat to lives and property when volcano flanks and surroundings are densely populated. The local impact of an eruption depends firstly on its location, whether it occurs near a volcano summit, or down on the flanks. Then forecasting, with a defined accuracy, the location of a potential, imminent eruption would significantly improve the assessment and mitigation of volcanic hazards. Currently, the conventional volcano monitoring methods based on the analysis of surface deformation assesses whether a volcano may erupt but are not implemented to locate imminent eruptions in real time. Here we show how surface deformation induced by ascending eruptive feeders can be used to forecast the eruption location through a simple geometrical analysis. Our analysis builds on the results of 33 scaled laboratory experiments simulating the emplacement of viscous magma intrusions in a brittle, cohesive Coulomb crust under lithostatic stress conditions. The intrusion-induced surface deformation was systematically monitored at high spatial and temporal resolution. In all the experiments, surface deformation preceding the eruptions resulted in systematic uplift, regardless of the intrusion shape. The analysis of the surface deformation patterns leads to the definition of a vector between the center of the uplifted area and the point of maximum uplift, which systematically acted as a precursor to the eruption's location. The temporal evolution of this vector indicated the direction in which the subsequent eruption would occur and ultimately the location itself, irrespective of the feeder shapes. Our findings represent a new approach on how surface deformation on active volcanoes that are not in active rifts could be analysed and used prior to an eruption with a real potential to improve hazard mitigation.

  • 266.
    Gunnarsson, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mineralogical speciation of sulfur in acid sulfate soils from Luleå, Sweden2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Marine sulfide – bearing sediments that oxidize when in contact with oxygen and leach outelements in high concentrations to small watercourses have been a problem for many years allover the world especially around the Bothnian Bay. The purpose of this study was to furtherinvestigate the sulfur mineralogy present in acid sulfate soils in the area of Luleå, Sweden. Asecondary aim was to see if elements leach out and accumulate in an acid sulfate soil closer tothe recipient. Samples were taken in two profiles (one oxidized and one waterlogged) fromfour sites (sites A-D) and were analyzed for whole rock geochemistry. Two sites were furtherinvestigated for mineralogy in polished samples with an optical microscope, Ramanspectroscopy and SEM-EDS. Each profile consisted of three layers: oxidation zone, transitionzone and reduced zone. The oxidation zone above the groundwater table was light grey withbrown iron hydroxide staining. Parts that lied under the water table were dark grey-black within general strong odor (“rotten eggs”) due to its sulfur content. It was usually straightforwardto distinguish and separate the layers from each other directly in the field, however in somecases pH was needed for confirmation.A general feature of investigated polished samples is the presence of abundant framboidalpyrites that are common in reduced marine sediments. The transition zone was formed in suboxicconditions and this feature is reflected by the mineralogy. Many morphologies of theframboidal pyrite were observed in this layer and signs of both dissolution and formationoccur. In the sample from site C one could observe elemental sulfur in form of large (up to 50μm) euhedral crystals. In the samples with pH<4, no sulfides occur as they have been replacedby jarosite (site B). Site C lacks these sulfur-bearing hydroxides which is thought to be due toa sulfur concentration of <0.2 %. Sulfur shows extensive leaching at most sites but at site B andD1, it accumulates in the transition zone. Elements like cobalt (Co), nickel (Ni) and zinc (Zn)are leached out or are accumulated further down in the profile. Elements that could have beentransported and have accumulated in the waterlogged profiles are Co, Ni, Zn and chromium(Cr) and in some profiles also copper (Cu) and vanadium (V).

  • 267. Gusmeroli, Alessio
    et al.
    Murray, Tavi
    Clark, Roger A.
    Kulessa, Bernd
    Jansson, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Vertical seismic profiling of glaciers: appraising multi-phase mixing models2013In: Annals of Glaciology, ISSN 0260-3055, E-ISSN 1727-5644, Vol. 54, no 64, p. 115-123Article in journal (Refereed)
    Abstract [en]

    We have investigated the speed of compressional waves in a polythermal glacier by, first, predicting them from a simple three-phase (ice, air, water) model derived from a published ground-penetrating radar study, and then comparing them with field data from four orthogonally orientated walkaway vertical seismic profiles (VSPs) acquired in an 80 m deep borehole drilled in the ablation area of Storglaciaren, northern Sweden. The model predicts that the P-wave speed increases gradually with depth from 3700 m s(-1) at the surface to 3760 m s(-1) at 80 m depth, and this change is almost wholly caused by a reduction in air content from 3% at the surface to <0.5% at depth. Changes in P-wave speed due to water content variations are small (<10 m s(-1)); the model's seismic cold-temperate transition surface (CTS) is characterized by a 0.3% decrease downwards in P-wave speed (about ten times smaller than the radar CTS). This lack of sensitivity, and the small contrast at the CTS, makes seismically derived water content estimation very challenging. Nevertheless, for down-going direct-wave first arrivals for zero- and near-offset VSP shots, we find that the model-predicted travel times and field observations agree to within 0.2 ms, i.e. less than the observational uncertainties.

  • 268.
    Gustavsson, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Martin, Selberg
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Delineation of Ditches in Wetlandsby Remote Sensing2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wetlands have been heavily affected by human-alteration, this is done to drain thewetland so that the ground can be used for other purposes such as forestry oragriculture. With high accuracy data available now, it is possible to use differentmethods automatically to identify these ditches in wetlands or other areas. Fourdifferent methods were applied to two areas to delineate ditches.

    To compare the different methods, the results were quantified by comparing with amanually created map of the ditches. Drainage density and an agreement index wereused. The results indicate that the methods of impoundment index and map gullydepth are best able to distinguish the ditches in wetlands. The former gave a betterresult on areas inside wetlands while the latter gave a better result with non-wetlandareas. The other two methods make mistakes and misjudgements that givemisleading results, they ignore ditches partially or completely, or finds ditches inareas without them. Even so, all methods are at least a clear improvement over thecurrently available property map's water flows, but not in the same class as the timeconsumingmanual method.

  • 269.
    Gärdebo, Johan
    et al.
    Philosophy and History, KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Marzecova, A.
    Knowles, S. G.
    The orbital technosphere: The provision of meaning and matter by satellites2017In: The Anthropocene Review, ISSN 2053-0196, E-ISSN 2053-020X, Vol. 4, no 1, p. 44-52Article in journal (Refereed)
    Abstract [en]

    With a new ‘technosphere’ concept, Peter Haff offers a provocative reconceptualization of technology in Anthropocene, not as derivative consequence of human activity, but as a new ‘quasi-autonomous’ sphere of the environment that conditions human survival within the Earth System. Paying attention to the expansion of the orbital satellites in outer space, this paper suggests that technosphere analysis needs to conceptualize specific histories of the planetary-scale technology while considering how these technologies provide the epistemological basis and limitations for the technosphere. Satellites enhance the capacity of the technosphere as a system and provide systemic knowledge that is the basis for the meaning of the technosphere concept. Yet, this expansion is rooted in the contingencies of earthly geopolitics and the continual breakdown of technology – in this instance as a space debris layer formed in orbit around Earth that endangers the technosphere itself.

  • 270.
    Gålfalk, Magnus
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlson, Martin
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Centre for Climate Science and Policy Research, CSPR.
    Crill, Patrick
    Stockholm Univ, Sweden.
    Bousquet, Philippe
    LSCE, France.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Technical note: A simple approach for efficient collection of field reference data for calibrating remote sensing mapping of northern wetlands2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 5, p. 1549-1557Article in journal (Refereed)
    Abstract [en]

    The calibration and validation of remote sensing land cover products are highly dependent on accurate field reference data, which are costly and practically challenging to collect. We describe an optical method for collection of field reference data that is a fast, cost-efficient, and robust alternative to field surveys and UAV imaging. A lightweight, waterproof, remote-controlled RGB camera (GoPro HERO4 Silver, GoPro Inc.) was used to take wide-angle images from 3.1 to 4.5 m in altitude using an extendable monopod, as well as representative near-ground (amp;lt; 1 m) images to identify spectral and structural features that correspond to various land covers in present lighting conditions. A semi-automatic classification was made based on six surface types (graminoids, water, shrubs, dry moss, wet moss, and rock). The method enables collection of detailed field reference data, which is critical in many remote sensing applications, such as satellite-based wetland mapping. The method uses common non-expensive equipment, does not require special skills or training, and is facilitated by a step-by-step manual that is included in the Supplement. Over time a global ground cover database can be built that can be used as reference data for studies of non-forested wetlands from satellites such as Sentinel 1 and 2 (10 m pixel size).

  • 271.
    Güner, Tuncay H.
    et al.
    University of Istanbul, Faculty of Forestry, Department of Forest Botany, Istanbul, Turkey.
    Bouchal, Johannes M.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bouchal, Johannes M.
    Swedish Museum of Natural History, Department of Paleobiology.
    Köse, Nesibe
    University of Istanbul, Faculty of Forestry, Department of Forest Botany, Istanbul, Turkey.
    Mayda, Serdar
    Göktaş, Fikret
    Landscape heterogeneity in the Yatağan Basin (southwestern Turkey) during the middle Miocene inferred from plant macro fossils2017In: Palaeontographica. Abteilung B, Palaophytologie, ISSN 0375-0299Article in journal (Refereed)
    Abstract [en]

    Plant macro fossils from the lignite mines of Eskihisar, Tınaz, and Salihpaşalar (Yatağan Basin, southwestern Anatolia) were investigated. The fossils were collected from marls overlying the exploited lignite seams and represent three subbasins within the main Yatağan Basin. The age of the Eskihisar lignite seam is well constrained by vertebrate fossils (MN 6, middle Miocene). Further, lithological and palynological correlation suggests that the lignite seams and overlying marls in the three lignite mines were formed at the same time. Three distinct zonal vegetation types are reflected in the local plant assemblages: (i) In Eskihisar, Fagus and evergreen Quercus mediterranea-Q. sosnowskyi communities formed important parts of the zonal vegetation along with the deciduous Quercus kubinyii; (ii) in Tınaz, Quercus sosnowskyi-Q. mediterranea-Q. drymeja communities occurred, while Fagus is rarely encountered in the macrofossil record. (iii) In Salihpaşalar, Quercus mediterranea and Q. drymeja are the most abundant elements, while Fagus and Q. sosnowskyi are absent or nearly so. This demonstrates that local environmental conditions within a geographically restricted region varied and probably were controlled by slope aspects, edaphic conditions, and river drainage. Overall, the zonal vegetation is characterized by a high diversity of evergreen and deciduous oaks belonging to Quercus subgen. Cerris sect. Ilex and sect, Cerris and the local dominance of Fagus. The riparian vegetation was dominated by Populus, Salix and Acer, whereas Alnus and taxodiaceous Cupressaceae and ferns were very rare or absent. The mass occurrence of Quercus sosnowskyi in the Yatağan Basin floras is biogeographically interesting, as this distinct sclerophyllous oak has previously been known to occur only in late Miocene sediments of northern Greece and Abkhasia (Georgia). 

  • 272.
    Hall, Adrian M.
    et al.
    University of St Andrews, Scotland, UK.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glacial and periglacial buzzsaws: fitting mechanisms to metaphors2014In: Quaternary Research, ISSN 0033-5894, E-ISSN 1096-0287, Vol. 81, no 2, p. 189-192Article in journal (Refereed)
    Abstract [en]

    The buzzsaw hypothesis refers to the potential for glacial and periglacial processes to rapidly denude mountains at and above glacier Equilibrium Line Altitudes (ELAs), irrespective of uplift rates, rock type or pre-existing topography. Here the appropriateness of the buzzsaw metaphor is examined alongside questions of the links between glacial erosion and ELAs, and whether the glacial system can produce low-relief surfaces or limit summit heights. Plateau fragments in mountains on both active orogens and passive margins that have been cited as products of glacial and periglacial buzzsaw erosion instead generally represent dissected remnants of largely inherited, pre-glacial relief. Summit heights may correlate with ELAs but no causal link need be implied as summit erosion rates are low, cirque headwalls may not directly abut summits and, on passive margins, cirques are cut into pre-existing mountain topography. Any simple links between ELAs and glacial erosion break down on passive margins due to topographic forcing of ice-sheet growth, and to the km-scale vertical swaths through which ELAs have shifted through the Quaternary. Glaciers destroy rather than create low-relief rock surfaces through the innate tendency for ice flow to be faster, thicker and warmer along valleys. The glacial buzzsaw cuts down.

  • 273.
    Hallström, Ellinor
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Payment for Ecosystem Services (PES) and Water Resource Management of the tropical mountain ecosystem páramo: A case study in the northern parts of Ecuador2017Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Latin America has pioneered the concept of Payment for Ecosystem Services (PES) as a strategy to improve the management of ecosystem services. Ecuador is not an exception, where many PES schemes have been implemented to protect the tropical mountain ecosystem “páramo” and the water resources these areas are generating for downstream societies. A successful PES scheme needs to achieve both targeted bio-physical objectives and at the same time benefit local conditions while not risking to sacrifice the local demand for ecosystem services. This balance is explored here in a case study focusing on the Río Grande watershed in the highlands in the northern parts of Ecuador by exemplifying community participation in the public PES scheme Socio Bosque (PSB) starting in 2009. The water resource distribution (precipitation, discharge, actual evapotranspiration and potential evapotranspiration) in the watershed was evaluated over the last decades. The local perception of the PSB and its impacts on local and regional water resources were also studied and characterized. The results showed that the annual discharge in the Río Grande watershed has decreased significantly from 1967-2014 and that the annual discharge was significantly lower between 1997-2015 compared to 1979-1997. Since precipitation did not decrease significantly during this period, the changes of the annual discharge are more likely depended on factors controlling the seasonal distribution of discharge and evapotranspiration in the watershed. For example, large scale land use changes coupled with a significantly warmer climate in the region could be a possible driver. Of course, this would not exclude other important factors such as changes in water demand and the supply of freshwater from the Río Grande watershed to downstream societies. The results of this case study showed that it is likely too early to see any impacts in the water balance components as a direct response to the implemented PSB scheme. Clearly, this motivates a need for continued evaluation of the local perception and the water resources to ensure that the need and demand for ecosystem services in a long-term perspective are maintained.

  • 274. Hammerli, Johannes
    et al.
    Kemp, Anthony IS
    Jeon, Heejin
    An Archean Yellowstone?: Evidence from extremely low δ18O in zircons preserved in granulites of the Yilgarn Craton, Western Australia2018In: Geology, Vol. 46, no 5, p. 411-414Article in journal (Refereed)
  • 275. Han, X.
    et al.
    Fraenz, M.
    Dubinin, E.
    Wei, Y.
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wan, W.
    He, M.
    Rong, Z. J.
    Chai, L.
    Zhong, J.
    Li, K.
    Barabash, S.
    Discrepancy between ionopause and photoelectron boundary determined from Mars Express measurements2014In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 41, no 23, p. 8221-8227Article in journal (Refereed)
    Abstract [en]

    The Martian ionosphere directly interacts with the solar wind due to lack of a significant intrinsic magnetic field, and an interface is formed in between. The interface is usually recognized by two kinds of indicators: the ionopause identified from ionospheric density profiles and the photoelectron boundary (PEB) determined from the electron energy spectrum at higher energies. However, the difference between them remains unclear. We have determined the locations of crossings of the ionopause and PEB from Mars Express observations during 2005-2013 and found that the average position of the PEB appears to be similar to 200km higher than that of the ionopause, which corresponds to 10(3)cm(-3) in the electron density profile. The discrepancy can be explained by cross-field transport of photoelectrons.

  • 276.
    Han, Zhiyong
    et al.
    Nanjing Univ, Sch Geog & Oceanog Sci, Nanjing 210023, Jiangsu, Peoples R China..
    Li, Xusheng
    Nanjing Univ, Sch Geog & Oceanog Sci, Nanjing 210023, Jiangsu, Peoples R China..
    Yi, Shuangwen
    Nanjing Univ, Sch Geog & Oceanog Sci, Nanjing 210023, Jiangsu, Peoples R China..
    Stevens, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Chen, Yingyong
    Nanjing Univ, Sch Geog & Oceanog Sci, Nanjing 210023, Jiangsu, Peoples R China..
    Wang, Xiaoyong
    Nanjing Univ, Sch Geog & Oceanog Sci, Nanjing 210023, Jiangsu, Peoples R China..
    Lu, Huayu
    Nanjing Univ, Sch Geog & Oceanog Sci, Nanjing 210023, Jiangsu, Peoples R China..
    Extreme monsoon aridity episodes recorded in South China during Heinrich Events2015In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 440, p. 467-474Article in journal (Refereed)
    Abstract [en]

    Geological records of climate change since the last glaciation in South China, a core area of the East Asian monsoon, are key to understanding secular variation in the monsoon system. However, with the exception of the speleothems, records from this area with independent age control are few. We investigated aeolian sand deposition on a sand hill on the shore of Poyang Lake in South China and reconstructed the chronological sequence of aeolian deposition using Optically Stimulated Luminescence (OSL) dating. Without exception, all aeolian sediments were deposited within seven periods that generally match the timing of Heinrich events and other cold periods in Greenland. We argue that aeolian sand accumulation in this region is most likely forced by extreme aridity driven by weakening of the summer monsoon, while the characteristics of this deposition are influenced by winter monsoon intensity. The monsoon shifts revealed here suggest a possible link between North Atlantic cooling and summer monsoon strength in South China, and support the intensities of cooling phases recorded in Greenland ice cores.

  • 277.
    Hanley, John
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Caballero, Rodrigo
    Stockholm University, Faculty of Science, Department of Meteorology .
    The role of large-scale atmospheric flow and Rossby wave breaking in the evolution of extreme windstorms over Europe2012In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 39, p. L21708-Article in journal (Refereed)
    Abstract [en]

    We investigate the relationship between large-scale atmospheric flow and the evolution of the most extreme windstorms affecting Western Continental Europe. The 25 most destructive Western Continental European wind storms are selected from a 43-year climatology. 22 of these storms are grouped as having a similar trajectory and evolution. We show that these storms typically occur during particularly strong and persistent positive NAO anomalies which peak approximately 2 days before the storms' peak intensity; the NAO pattern then shifts eastward to a position over the European continent when the storms strike Europe. A temporal composite of potential temperature on the 2-PVU surface suggests that this NAO shift is the result of simultaneous cyclonic and anticyclonic wave breaking penetrating further to the east than during a typical high-NAO event. This creates an extremely intense, zonally-orientated jet over the North Atlantic whose baroclinicity favours explosive intensification of storms while steering them into Western Continental Europe.

  • 278.
    Hannerz, Fredrik
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Lotsch, Alexander
    Assessment of remotely sensed and statistical inventories of African agricultural fields2008In: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, International Journal of Remote Sensing, Vol. 29, no 13, p. 3787-3804Article in journal (Refereed)
    Abstract [en]

    This paper critically examines different sources of remotely sensed and statistical inventories of African agricultural fields. Substantial discrepancies are found across alternative sources of information in both the extent and location of agricultural fields. In one-third of the countries, the difference between lowest and highest field extent estimate exceeds 25% of the total country area, and the maximum difference at the continental level is 2.6 million km2. Much of the disagreement between land-cover maps arises from areas of low cropping density. These inconsistencies have important implications when using these data directly, e.g. for the assessment of land cover changes, or indirectly in economic or physical models, and indicate a need to explicitly quantify uncertainties arising from the limitations in land-cover data. They also highlight the need for development of regional land information systems for baseline development and informed policy decisions.

  • 279. Harden, Jennifer W.
    et al.
    Koven, Charles D.
    Ping, Chien-Lu
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    McGuire, A. David
    Camill, Phillip
    Jorgenson, Torre
    Kuhry, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Michaelson, Gary J.
    O'Donnell, Jonathan A.
    Schuur, Edward A. G.
    Tarnocai, Charles
    Johnson, Kristopher
    Grosse, Guido
    Field information links permafrost carbon to physical vulnerabilities of thawing2012In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 39, p. L15704-Article in journal (Refereed)
    Abstract [en]

    Deep soil profiles containing permafrost (Gelisols) were characterized for organic carbon (C) and total nitrogen (N) stocks to 3 m depths. Using the Community Climate System Model (CCSM4) we calculate cumulative distributions of active layer thickness (ALT) under current and future climates. The difference in cumulative ALT distributions over time was multiplied by C and N contents of soil horizons in Gelisol suborders to calculate newly thawed C and N. Thawing ranged from 147 PgC with 10 PgN by 2050 (representative concentration pathway RCP scenario 4.5) to 436 PgC with 29 PgN by 2100 (RCP 8.5). Organic horizons that thaw are vulnerable to combustion, and all horizon types are vulnerable to shifts in hydrology and decomposition. The rates and extent of such losses are unknown and can be further constrained by linking field and modelling approaches. These changes have the potential for strong additional loading to our atmosphere, water resources, and ecosystems. Citation: Harden, J. W., et al. (2012), Field information links permafrost carbon to physical vulnerabilities of thawing, Geophys. Res. Lett., 39, L15704, doi: 10.1029/2012GL051958.

  • 280.
    Hargelius, Malcolm
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Hansbokorrelationens tillförlitlighet för kommersiella syften2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Geotechnicans in Sweden and rest of Scandinavia have a wide experience of stability calculations in cohesive soils. The two main parameters for this type of calculations are the undrained shear strength and the preconsolidation pressure. The most common methods in Sweden to determine the undrained shear strength in field is the vane shear strength test and CPT-test, in laboratories the fall cone test is well used. To determine the preconsolidation pressure CRS-analyses are well used. For more accurate measurements the odeometer tests are more suitable. However this method is both expensive and time-consuming form of analysis from a commercial aspect. Therefore is different correlation equations used as a compliment in these different stability evaluations. 

    This research will focus on the empirical Hansbo Correlation and its relation to results from commercial surveys. The commercial data come from Atkins Sverige’s project data base. The results after comparing Hansbo correlation with the commercial data showed on a significant divergence, which indicate a great unsureness of the Hansbo correlation. As a result of this contingency it is of importance to take cautiousness in the use of empirical correlations in stability calculations. 

  • 281.
    Hargelius, Malcolm
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Modellering och analys av grundvattenflödet i en byggnads grundläggning2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Most of Sweden’s older buildings constructed in clay rich areas are founded on wood poles. The poles are used to build the constructions in areas with soils without satisfying stability, such e.g. clay soils, where the poles are used as the “stable ground” where the building are founded upon. One of the problems with wood poles are that to prevent the wood from rotting the poles must be covered with water, to make an oxygen free environment. The problems start first when the water levels start to decrease due to dewatering or if the water is contaminated with bacteria from e.g. leaky sewer pipes. The contamination leads to decomposing of the wood, which affect the stability of the poles negatively. To prevent the leaky aquifers many houses, have water supply by wells where water is added to the aquifer to keep the water at stable levels.

    In Uppsala, Sweden an apartment building founded on wood poles have this problems with a contaminated and leaky aquifer. The reason to the contamination was an old sewer pipe that start leaking due to subsidence of the clay below the house. The dewatering of the aquifer was detected in 2016 when the water supply to the aquifer increased from 10th of cubic meters per year to 10th of cubic meters per day.

    In an attempt to find out what the reason to the high discharge from the aquifer a groundwater model was constructed to modelling the groundwater flows below the building. To modeling this problem the software Groundwater Modeling System (GMS) and MODFLOW was used. By construct a 3D grid of cells in the same dimensions as the building divided in to three different layers it was possible to simulating the groundwater flow through the aquifer.

    The way we did it was by knowing that as part of the foundation there was “channels” filled with gavel above the poles. The hypothesis was that the water was flowing through this high hydraulic conductivity “gravel channels” and there for we used the model to performed calculations of the hydraulic conductivity in the channels and the areas around the channels. The results told us that there were high conductivity zones in the south west part of the building. After the calculation of the conductivity, a test was performed, where the water supply where turned off and the decrease of the water levels was measured.

    By using this calculated hydraulic conductivity and the observed levels from the water supply test we let the model calculate the change of water level during the whole-time series. The results told us that there was a possible groundwater flow to the sought west and that some sort of threshold in the channel prevented the water to sink below a curtain limit of 7.65 meter.

  • 282.
    Harrie, Lars
    et al.
    Lund University.
    Larsson, Karin
    Lund University.
    Tenenbaum, David
    Lund University.
    Horemuz, Milan
    Royal Institute of Technology (KTH).
    Ridefelt, Hanna
    National mapping and land registration authority, Gävle, Sweden.
    Lysell, Gunnar
    National mapping and land registration authority, Gävle, Sweden.
    Brandt, S. Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sahlin, Eva A.U.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Adelsköld, Göran
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Högström, Mats
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Lagerstedt, Jakob
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Some strategic national initiatives for the Swedish education in the geodata field2014In: Connecting a Digital Europe through Location and Place: Selected best short papers and posters of the AGILE 2014 Conference, 3‐6 June 2014, Castellón, Spain / [ed] Joaquin Huerta, Sven Schade, Carlos Granell, AGILE Digital Editions , 2014Conference paper (Refereed)
    Abstract [en]

    This paper describes national cooperation in Sweden launched by its universities and authorities, aimed at improving geodata education. These initiatives have been focused upon providing common access to geodata, the production of teaching materials in Swedish and organizing annual meetings for teachers. We argue that this type of cooperation is vital to providing high quality education for a poorly recognized subject in a country with a relatively small population.

  • 283. Harrison, John A.
    et al.
    Frings, Patrick J
    Swedish Museum of Natural History, Department of Geology.
    Beusen, Arthur H. W.
    Conley, Daniel J.
    McCrackin, Michelle L.
    Global importance, patterns, and controls of dissolved silica retention in lakes and reservoirs2012In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 26, no 2, p. n/a-n/aArticle in journal (Refereed)
    Abstract [en]

    Lentic water bodies (lakes and reservoirs) offer favorable conditions for silica (SiO2) burial in sediments. Recent global estimates suggest that (1) lentic SiO2 trapping is a globally important SiO2 flux, and (2) through reservoir construction, humans have dramatically altered river dissolved SiO2 (DSi) transport and coastal DSi delivery. However, regional to global scale patterns and controls of DSi removal in lentic systems are poorly constrained. Here we use 27 published lake and reservoir DSi budgets to develop insights into patterns and controls of lentic DSi retention and to develop a new, spatially explicit, global model of lentic DSi removal called SiRReLa (Silica Retention in Reservoirs and Lakes). In our analysis, lentic DSi removal (kg SiO2 yr−1) was significantly and positively related to DSi loading (P < 0.0001; r2 = 0.98), and DSi removal efficiency was significantly and positively related to water residence time (P < 0.0001; r2 = 0.68). In addition, DSi settling rates were, on average, 6.5-fold higher in eutrophic systems than in non-eutrophic systems (median settling velocities: 11.1 and 1.7 m yr−1 for eutrophic and non-eutrophic systems, respectively; P < 0.01). SiRReLa, which incorporates these insights, performed quite well in predicting both total DSi removal (kg SiO2 yr−1; Nash Sutcliffe Efficiency (N.S.E) = 0.88) and DSi removal efficiency (% Si removed; N.S.E. = 0.75), with no detectable bias in the model. Global application of SiRReLa confirms that lentic systems are important sinks for DSi, removing 89.1 Tg DSi yr−1 from watersheds globally, roughly 19–38% of all DSi inputs to surface waters. Small lakes and reservoirs (<50 km2) were critical in the analysis, retaining 81% (72 Tg DSi yr−1) of the globally retained total. Furthermore, although reservoirs occupy just 6% of the global lentic surface area, they retained approximately 35% of the total DSi removed by lentic systems. Regional hot spots for lentic DSi removal were identified and imply that lentic systems can remove the vast majority of DSi across a large fraction of Earth's land surface. Finally, a sensitivity analysis indicates that future improvements in DSi trapping and transport models should focus on improving estimates of DSi input to surface waters.

  • 284.
    Hartman, Steven
    Mid Sweden University, Faculty of Human Sciences, Department of Humanities.
    Unpacking the Black Box: the need for Integrated Environmental Humanities (IEH)2015Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The circumstances that have given rise to the Anthropocene concept require that we reassess our assumptions about human agency and human effects on the earth system. Human activities, and thus human choices, clearly lie at the root of the great environmental predicament of our age, which is not primarily an ecological crisis, though its ramifications are far reaching within ecological systems. Rather, it is a crisis of culture. If the humanities "are a unique repository of knowledge and insight into the rich diversity of the human experience" from which we learn to make sense of our "responses, motivations and actions" in the face of challenges, then it is risky to omit humanities knowledge from scientific assessment and consultation processes informing environmental policy.

    The complete article is available for free viewing on the Future Earth site: bit.ly/1QoHPeC .

  • 285. He, Hongxing
    et al.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Svensson, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Bjorklund, Jesper
    Tarvainen, Lasse
    Klemedtsson, Leif
    Kasimir, Asa
    Forests on drained agricultural peatland are potentially large sources of greenhouse gases - insights from a full rotation period simulation2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 8, p. 2305-2318Article in journal (Refereed)
    Abstract [en]

    The CoupModel was used to simulate a Norway spruce forest on fertile drained peat over 60 years, from planting in 1951 until 2011, describing abiotic, biotic and greenhouse gas (GHG) emissions (CO2 and N2O). By calibrating the model against tree ring data a "vegetation fitted" model was obtained by which we were able to describe the fluxes and controlling factors over the 60 years. We discuss some conceptual issues relevant to improving the model in order to better understand peat soil simulations. However, the present model was able to describe the most important ecosystem dynamics such as the plant biomass development and GHG emissions. The GHG fluxes are composed of two important quantities, the spruce forest carbon (C) uptake, 413 g C m(-2) yr(-1) and the decomposition of peat soil, 399 g C m(-2) yr(-1) . N2O emissions contribute to the GHG emissions by up to 0.7 g N m(-2) yr(-1), corresponding to 76 g C m(-2) yr(-1) . The 60-year old spruce forest has an accumulated biomass of 16.0 kg C m(-2) (corresponding to 60 kg CO2 m(-2)). However, over this period, 26.4 kg C m(-2) (97 kg CO2 eq m(-2)) has been added to the atmosphere, as both CO2 and N2O originating from the peat soil and, indirectly, from forest thinning products, which we assume have a short lifetime. We conclude that after harvest at an age of 80 years, most of the stored biomass carbon is liable to be released, the system having captured C only temporarily and with a cost of disappeared peat, adding CO2 to the atmosphere.

  • 286. He, Wenyan
    et al.
    Yang, Liqiang
    Lu, Yongjun
    Jeon, Heejin
    Xie, Shixiong
    Gao, Xue
    Zircon U–Pb dating, geochemistry and Sr–Nd–Hf–O isotopes for the Baimaxueshan granodiorites and mafic microgranulars enclaves in the Sanjiang Orogen: Evidence for westward subduction of Paleo-Tethys2018In: Gondwana ResearchArticle in journal (Refereed)
  • 287.
    Hedayati, Maryeh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Sharma, Prabhakar
    Nalanda Univ, Sch Ecol & Environm Studies, Nalanda 803116, Bihar, India.
    Katyal, Deeksha
    Guru Gobind Singh Indraprastha Univ, Sch Environm Management, New Delhi, India.
    Fagerlund, Fritjof
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Transport and retention of carbon-based engineered and natural nanoparticles through saturated porous media2016In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 18, no 3, article id 57Article in journal (Refereed)
    Abstract [en]

    Carbon-based engineered nanoparticles have been widely used due to their small size and unique physical and chemical properties. At the same time, the toxic effects of these nanoparticles on human and fish cells have also been observed; therefore, their release and distribution into the surface and subsurface environment is a subject of concern. The aim of this research is to evaluate and compare the transports and retentions of two types of engineered nanoparticles (multiwalled carbon nanotubes and C-60) and the natural carbon nanoparticles collected from a fire accident. Several laboratory experiments were conducted to observe the transport behavior of nanoparticles through a column packed with silica sand. The column experiments were intended to monitor the effect of ionic strength on transport of nanoparticles as a function of their shapes. It was observed that the mobilities of both types of engineered nanoparticles were reduced with the increasing ionic strength from 1.34 to 60 mM. However, at ionic strengths up to 10.89 mM, spherical nanoparticles were more mobile than cylindrical nanoparticles, but the mobility of the cylindrical nanoparticles became significantly higher than spherical nanoparticles at the ionic strength of 60 mM. In comparison with natural fire-born nanoparticles, both types of engineered nanoparticles were much less mobile under the selected experimental condition in this study. Furthermore, inverse modeling was used to calculate parameters such as attachment efficiency, the longitudinal dispersivity, and capacity of the solid phase for the attachment of nanoparticles. The results indicate that the combination of the shape and the solution chemistry of the NPs are responsible for the transport and the retention of nanoparticles in natural environment; however, fire-burned nanoparticles can be highly mobile at the natural groundwater chemistry.

  • 288.
    Hedmark, Mia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Inventering och sammanställning av publikationer inom geovetenskaplig didaktik2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis presents a general definition of science education and earth science education.An inventory has been conducted of published material during the years 2011-2013, withthe start in 2013 and working backwards for international publications and with no timelimits in time for Swedish publications. Different databases were used during April 2013 forthe inventory.The thesis organizes and analyses published material in earth science education in a tablewith a following discussion.The purpose with the inventory was to investigate the amount and content ofprevious year’s publications in earth science education. Concept inventories were foundto be the most common subject of the found material, followed by virtual field studies. Thelargest amount of publications was published in North America. Only one publication wasfound in Sweden.

  • 289.
    Heingård, Miriam
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    The Function of FoxB During Limb Development and Axis Formation in the Spider Parasteatoda tepidariorum2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Arthropods are the most diverse and speciose group of animals on the planet. A key factor in their success is the adaptation of various appendages to new functions and environments, resulting in radically different morphologies. To understand this diversity, it is important to study the underlying genetic mechanisms. However, the gene regulatory networks governing the development of limbs are relatively poorly understood in many arthropods. The FoxB gene is known to have a conserved expression pattern in all arthropods hitherto investigated. It is expressed along the ventral ectoderm of all appendages, indicative of a function in ventral limb patterning. In this study, I conducted a functional analysis of FoxB in the house spider Parasteatoda tepidariorum by means of parental RNA interference. The knockdown of FoxB resulted in severe phenotypes of arrested development and inability to form proper germ bands, hypothesized to be the consequence of FoxB working antagonisitcally to dpp, a gene crucial for dorsal field formation and axial symmetry in Parasteatoda. Embryos depleted of FoxB had abnormal limbs characterized by an L-shaped morphology, likely caused by an absence or alteration of ventral limb morphology. I also present evidence that FoxB is likely upstream of the ventrally expressed genes wingless and H15-2 and probably a repressor of the dorsal limb marker optomotor-blind. Furthermore, I show for the first time that FoxB is expressed ventrally in Drosophila imaginal leg discs and in the antennal disc. The present study demonstrates the conserved ventral limb expression of FoxB in arthropods, and evidence for a role in limb patterning in spiders. FoxB appears to be an excellent candidate gene for studying ventral limb development in arthropods, and has potential to be the focus of future studies investigating this topic.

    The full text will be freely available from 2019-12-31 12:00
  • 290.
    Helanow, Christian
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Effects of numerical implementations of the impenetrability condition on non-linear Stokes flow: applications to ice dynamicsManuscript (preprint) (Other academic)
    Abstract [en]

    The basal sliding of glaciers and ice sheets can constitute a large part of the total observed ice velocity, in particular in dynamically active areas. It is therefore important to accurately represent this process in numerical models. The condition that the sliding velocity should be tangential to the bed is realized by imposing an impenetrability condition at the base. We study the, in glaciological literature used, numerical implementations of the impenetrability condition for non-linear Stokes flow with Navier's slip on the boundary. Using the finite element method, we enforce impenetrability by: a local rotation of the coordinate system (strong method), a Lagrange multiplier method enforcing zero average flow across each facet (weak method) and an approximative method that uses the pressure variable as a Lagrange multiplier for both incompressibility and impenetrability. An analysis of the latter shows that it relaxes the incompressibility constraint, but enforces impenetrability approximately if the pressure is close to the normal component of the stress at the bed. Comparing the methods numerically using a method of manufactured solutions unexpectedly leads to similar convergence results. However, we find that, for more realistic cases, in areas of high sliding or varying topography the velocity field simulated by the approximative method differs from that of the other methods by approx. 1% (two dimensional flow) and  > 5% when compared to the strong method (three-dimensional flow). In this study the strong method, which is the most commonly used in numerical ice sheet models, emerges as the preferred method due to its stable properties (compared to the weak method in three dimensions) and ability to well enforce the impenetrability condition.

  • 291.
    Helanow, Christian
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Ahlkrona, Josefin
    Galerkin Least-Squares Stabilization in Ice Sheet Modeling - Accuracy, Robustness, and Comparison to other TechniquesManuscript (preprint) (Other academic)
    Abstract [en]

    We investigate the accuracy and robustness of one of the most common methods used in glaciology for the discretization of the p-Stokes equations: equal order finite elements with Galerkin Least-Squares (GLS) stabilization. Furthermore we compare the results to other stabilized methods. We find that the vertical velocity component is more sensitive to the choice of GLS stabilization parameter than horizontal velocity. Additionally, the accuracy of the vertical velocity component is especially important since errors in this component can cause ice surface instabilities and propagate into future ice volume predictions. If the element cell size is set to the minimum edge length and the stabilization parameter is allowed to vary non-linearly with viscosity, the GLS stabilization parameter found in literature is a good choice on simple domains. However, near ice margins the standard parameter choice may result in significant oscillations in the vertical component of the surface velocity. For these cases, other stabilization techniques, such as the interior penalty method, result in better accuracy and are less sensitive to the choice of the stabilization parameter. During this work we also discovered that the manufactured solutions often used to evaluate errors in glaciology are not reliable due to high artificial surface forces at singularities. We perform our numerical experiments in both FEniCS and Elmer/Ice.

  • 292.
    Hell, Benjamin
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jakobsson, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Gridding heterogeneous bathymetric data sets with stacked continuous curvature splines in tension2011In: Marine Geophysical Researches, ISSN 0025-3235, E-ISSN 1573-0581, Vol. 32, no 4, p. 493-501Article in journal (Refereed)
    Abstract [en]

    Gridding heterogeneous bathymetric data sets for the compilation of Digital bathymetric models (DBMs), poses specific problems when there are extreme variations in source data density. This requires gridding routines capable of subsampling high-resolution source data while preserving as much as possible of the small details, at the same time as interpolating in areas with sparse data without generating gridding artifacts. A frequently used gridding method generalizes bicubic spline interpolation and is known as continuous curvature splines in tension. This method is further enhanced in this article in order to specifically handle heterogeneous bathymetric source data. Our method constructs the final grid through stacking several surfaces of different resolutions, each generated using the splines in tension algorithm. With this approach, the gridding resolution is locally adjusted to the density of the source data set: Areas with high-resolution data are gridded at higher resolution than areas with sparse source data. In comparison with some of the most widely used gridding methods, our approach yields superior DBMs based on heterogeneous bathymetric data sets with regard to preserving small bathymetric details in the high-resolution source data, while minimizing interpolation artifacts in the sparsely data constrained regions. Common problems such as artifacts from ship tracklines are suppressed. Even if our stacked continuous curvature splines in tension gridding algorithm has been specifically designed to construct DBMs from heterogeneous bathymetric source data, it may be used to compile regular grids from other geoscientific measurements.

  • 293.
    Hellqvist, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Kvartärgeologi och landskapsanalys2011Report (Other academic)
    Abstract [sv]

    Landskapsanalysen runt utgrävningen i Nibble baseras framför allt på en jordartsgeologisk detaljkartläggning. För annan typ av information kring landskapets förändring och utveckling, har använts tidigare undersökningar i områdets närhet eller i denna del av Uppland och Västmanland. Anledningen till detta arbetssätt är flera. Dels är landskapsutvecklingen i många delar mycket likartad i regionen, dels har mycket av den paleoekologiska insatsen koncentrerats på detaljstudier av anläggningar och närmiljön i Nibble och dels har kunskapen om jordarterna och deras karaktär i detalj för ytan ganska stor betydelse för förståelsen av ytorna på utgrävningsplatsen samt även anläggningarnas karaktär och utseende. Bland annat förekom mycket diskussioner om vissa anläggningar och karaktären på områdets moränavsättningar.

    Den jordartsgeologiska detaljkartläggningen är en presentation av i första hand jordartsgeologin i området runt Nibble, ca 4 km väster om Enköping. Karteringen baseras främst på undersökning i fält, provtagning och grundläggande jordartsanalys i samband med den arkeologiska slutundersökningen i maj t.o.m. oktober 2007. I samband med den geologiska kartläggningen, har det tagits ett antal jordartsprover i utgrävningsområdet (se nedan). Syftet är bl.a. att göra själva jordartsklassificeringen mer komplett och därmed stärka den detaljerade kartläggningen. Ett annat syfte är att ge en möjlighet till tolkning av markanvändningen i området och hur man utnyttjat marken för odling och hur detta återspeglas i de kulturlager som finns kvar idag.

    Till detta kommer även uppgifter från litteraturstudier, men då platsen och området runt Nibble inte ingått i några tidigare undersökningar eller speciella studier, så finns det inte några tidigare detaljstudier eller undersökningar att tillgå. Den jordartsgeologiska karteringen (Möller, 1985) som Sveriges Geologiska Undersökning (SGU) genomfört i området är naturligtvis ett viktigt komplement i sammanhanget och uppgifter från den används som jämförelsematerial till de resultat som framkommit i samband med kartläggningen av Nibble 2007. I de sammanhangen refereras till uppgifter på kartbladet Enköping SV och är därför mer karakteristika och specifika drag för jordartgeologin kopplade till en radie om > 5 km runt Nibble. Till detta kommer en del referenser från bl.a. Enköpingstrakten, där det framför allt finns undersökningar kring Enköpingsåsen.

                          Nibble ligger på många sätt i relativt klassisk kvartärgeologisk mark med tanke på att hela Mälardalsregionen varit föremål för stort intresse och undersökningar under lång tid. Detta har även möjliggjorts eftersom det är en expansiv region med mycket samhällen och återkommande arbeten med infrastruktur. I områdena tunt Enköping finns stora slättområden, uppbyggda av framför allt finsediment som lera, vilket ger speciella förutsättningar för det arkeologiska utgrävningsarbetet och bevarandeförhållanden. Det undersökta området har helt legat under havsytan efter senaste istidens avslutning (Weichsel) och sedimentation av finsediment har skett i akvatisk miljö. Därför domineras jordartsgeologin till stora delar av glaciala postglaciala leror.

  • 294.
    Hellqvist, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moränkällan2011Report (Other academic)
    Abstract [sv]

    Under utgrävningarna i Nibble så framkom ett för arkeologiska utgrävningar ovanligt fynd i form av en naturlig källa. Sannolikt har likartade bildningar hittats i samband med utgrävningar tidigare, men att kunna klassificera en sådan bildning redan i samband med slutundersökningens tidiga skede och att kunna klassificera vilken typ av källa det rör sig om är nog mycket unikt. Källor är normalt klassificerade utifrån det hydrogeologiska sammanhang och den miljö de är bildade i och om man, som sker i samband med en arkeologisk utgrävning, skalar av markskiktet så kan det naturligtvis bli svårt att urskilja att det faktiskt rör sig om en källa. Fördelen med källan i Nibble är att utflödet för vattnet i marken skedde vid en ansamling av stora block och därför ”skyddades” detta från att på något sätt förstöras i samband med avbaning av markskiktet i samband med utgrävningen eller annan tidigare markanvändning.

    I naturen avslöjas källor ofta genom ett utflöde i marken som via markens fuktighet och växtlighet. Källor har spelat stor roll i kulturhistorien och det vi idag kan se på platser som tydliga källor är ofta utbyggda och arrangerade av människor som har ramat in, skyddat eller på något sätt markerat utflödet bl.a. för att i olika syften kunna utnyttja källans vatten som ofta håller mycket hög kvalitet. Den sista fasen i denna kulturhistoriska utveckling var utvecklandet av brunnsdrickning som förekommit från åtminstone 1600-talet och fram till 1900-talet. Flera av Sveriges kända sådana platser har idag gett namn åt kolsyrat vatten på flaska, som exempelvis Loka brunn och Ramlösa brunn. Vissa har med tiden övergått i mer moderniserade s.k. ”spa-anläggningar” som exempelvis Sätra brunn.

    Med tanke på källans vatten och det fenomen då vattnet kommer fram ur marken, så kan man lätt tänka sig att källan måste ha varit föremål för människors förundran och kanske tro långt tillbaka i tiden. Betydelsen och värdet av källor har dock förändrats genom historien, både i tro och också kult. I de förkristna källor som kan ge en vägledning, de isländska berättelserna genom poetiska Eddan, så berättas att källorna var förutsättningen för världen och om källorna sinade så skulle världen gå under. Även det omtalade trädet Yggdrasil fick sitt vatten från tre källor. Uppfattningen om världens undergång kommer via germansk tradition och spåras tillbaka till indoeuropeisk mytologi (Hult, 2006).

    En tidigare vanlig uppfattning kring källor och dess vatten var att de hade en helande förmåga och även kunde hjälpa försvagade och sjuka kroppar. Man trodde även på källans mystiska krafter. Källor och källvatten kom att få en stark ställning i den katolska kyrkan och även i Sverige finns exempel på helgonkällor och ännu vanligare är källor som benämns trefaldighets- och midsommarkällor. Dessa källor har varit en viktig del i trefaldighetsfirande, ibland även valborgsmässofirande och liknande. Denna tradition anses av en del ha sina rötter i vad som kallats ”hednisk källkult” med ett ursprung i förhistorisk tid.

    Traditioner kring vissa källor har en kulturhistorisk bakgrund i tron kring källorna som går tillbaka till medeltiden och bl.a. den katolska kyrkan i Sverige. Under reformationen förändrades synen på källorna och 1544 förbjöds svenskarna att dricka hälsa från trefaldighetskällorna. I det protestantiska Sverige kom seden att dricka källa att kallas för katolsk vidskepelse (Hult, 2006). Sedan dess har mycket hänt i synen på källorna fram till modern tid och idag är seder kring källor mer att betrakta som pittoreska traditionsinslag där människor får möjlighet att samlas.

    Till all denna tro och kult ska man naturligtvis tillägga, att källor i stor utsträckning fungerat som källa för vatten – både på landsbygden och i städer. Möjligheten att använda dessa platser för att få tillgång till friskt och bra vatten som strömmar ut ur marken, utan att man behöver ta upp detta själv, har naturligtvis använts flitigt när det är möjligt.

  • 295.
    Hellqvist, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Reconstructing environment and human impact during 1500 years of mining activity around FalunCopper mine, Sweden, through a multidisciplinary approach2013In: Environmental and Archaeological Science Conference: AEA & UKAS 2013 Cardiff University 11th-14th April 2013, 2013Conference paper (Refereed)
    Abstract [en]

    Mining impact on the surrounding environment is one of the most severe human activities. The time the mining has been lasting is usually proportional to and increases the impact on the surrounding environment. In the interdisciplinary project presented in this paper, ”Falun above from Falun under”, is the earliest history from around 1300-1500 BP studied together with the increasing environmental impact of growing mining activity around Falun Copper mine. The environmental and cultural development is followed forward until the mine is lastly abandoned in 1992.

    The projects aim is to study the area unbiased and explore previous reference as well as initiating new investigations. The project use the British project ”Great Yarmouth Archaeological map project” as a model. Falun Copper mine have a central and in time long part in Sweden and was 2001 established as a UNESCO World Heritage and is therefore in some parts rather well studied –primarily in archaeology, earth science and history. Within the project today is several methods used and under development: sedimentological mapping, reconstruction and analysis; insect and pollen analysis; dendrochronology; GIS; archive material and previous archaeological and geotechnical reports etc. There are also studies connected to preservation (World Heritage) and environmental history pedagogy and didactics.

  • 296.
    Hellqvist, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Johansson, Jenny
    Almgren, Elisabeth
    Traustadottir, Ragnheidur
    Environmental and climatic changes during the late Holocene in Hjaltadalur, Skagafjörður, northern Iceland, interpreted from peat core analyses and pollen identification2016In: Theme B - Landscape Historical Ecology and Climate Change: B1 Land-use and Anthropogenic Land-cover Change over the Holocene - Information of Value for Climate and Environmental Research, 2016Conference paper (Refereed)
    Abstract [en]

    A landscape analysis based on a combination of several proxies including pollen analysis, loss on ignition, radiocarbon dating, sediment analysis and tephra analysis was undertaken on samples from Hjaltadalur, northern Iceland. The central settlement in the valley, Hólar, is an important site that was once the religious and cultural centre of northern Iceland. Sampling was done in wetlands and one mire (Viðvik) was chosen as the main study site for sampling and analyses. The results provide useful information and insights into temperature fluctuations and climatic development during the late Holocene. In the pollen record there is a transition from a warm and dry forest-like landscape to a cooler, more humid, open landscape during the last 5000 years, with a marked shift from a warm and dry to a cool and humid climate around 2500 years ago. Human activities are reflected by a distinct peak in the Compositae-pollen curve in the uppermost sequence of the sediment core that is indicative of the settlement period during the years AD 870-930. The climatic transition, which contributed to a reduction of the birch population, started before human settlement and the Landnám period (AD 870-930) and thus implies that humans were not solely responsible for the birch decline and the transition of the landscape from forest-like conditions to a more open environment, although the subsequent Viking Age and later settlements continued the afforestation trend.

  • 297.
    Hellqvist, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Lundqvist, Jennie
    Hedmark, Mia
    Developing Earth Science education research2014In: 31st Nordic Geological Winter Meeting. Lund, Sweden, January 8-10 2014. Scientific program: Outreach and Education: Reaching out with WOW to the many, Lund: Geologiska Föreningen , 2014, p. 167-167Conference paper (Refereed)
    Abstract [en]

    This paper presents an attempt to build up research within the field earth science education, presenting results from interview studies on the student’s experience of participation to Earth science (1st year earth science students), inventory on previous research, interviews of primary school pupils and a public survey of knowledge in earth science. In Sweden, there is almost no research on Earth science education, the field within science education concerning Earth Science. In both European and international perspective this is in opposite to Physics, Computer science, Chemistry and Biology. Also in an international perspective the published research on Earth science education is very low, with one exceptional exception in North America where there is a lot of research in science education of different subjects. The largest number of publications is, therefore, also published in North America. The subjects of highest interest in previous earth science education research are on questions about misconceptions, concept inventories and field related education, where virtual field studies is of special interest.

    In the attempt to build up research, focus is primarily on education and teaching in university studies, but pre-university studies (primary & secondary school; upper secondary school) and the public knowledge on Earth science are also of interest. The studies focus on: experience of participation (i.e. identity); managing difficult and/or advanced questions; misconceptions; education in particular fields, especially field studies and laboratory work. Methodological the research is mainly performed through quantitative and qualitative data analysis, case study research and phenomenographic approaches.

  • 298.
    Henderiks, Jorijntje
    Stockholm University.
    Coccolithophore size rules — Reconstructing ancient cell geometry and cellular calcite quota from fossil coccoliths2008In: Marine Micropaleontology, ISSN 0377-8398, E-ISSN 1872-6186, Vol. 67, no 1-2, p. 143-154Article in journal (Refereed)
  • 299.
    Henderiks, Jorijntje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Size of marine phytoplankton: Why does it matter?2011Conference paper (Other academic)
    Abstract [en]

    Marine phytoplankton, such as diatoms and coccolithophores, constitute the base of the marine food chain and are a fundamental component in biogeochemical cycles. The overall ecological success of marine phytoplankton, but also its taxonomic diversity and size distribution, determines the efficiency by which fixed carbon is transferred to higher trophic levels and into the deep ocean- and sedimentary carbon reservoirs. In recent years, several hypotheses have been invoked to explain distinct macroevolutionary decreases in the cell size of phytoplankton during the Cenozoic. Global, long-term cooling has been cast a major role in driving these cell size decreases. Despite overall correspondence between long-term trends, however, it's becoming more and more clear that not all phytoplankton dance to the same tune. The latter is particularly evident when looking at different coccolithophore lineages. Here, I will review the state-of-the-art and highlight some open avenues that are worth exploring.

  • 300.
    Henderiks, Jorijntje
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Hannisdal, Bjarte
    Centre for Geobiology, Dept. of Earth Sciences, University of Bergen, N.
    Liow, Lee Hsiang
    CEES, Dept. of Biology, University of Oslo, N.
    Calcifying phytoplankton biomass and CO2: A striking balance2010Conference paper (Other academic)
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