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  • 1. Anderson, N. John
    et al.
    Saros, Jasmine E.
    Bullard, Joanna E.
    Cahoon, Sean M. P.
    Mcgowan, Suzanne
    Bagshaw, Elizabeth A.
    Barry, Christopher D.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Burpee, Benjamin T.
    Carrivick, Jonathan L.
    Fowler, Rachel A.
    Fox, Anthony D.
    Fritz, Sherilyn C.
    Giles, Madeleine E.
    Hamerlik, Ladislav
    Ingeman-Nielsen, Thomas
    Law, Antonia C.
    Mernild, Sebastian H.
    Northington, Robert M.
    Osburn, Christopher L.
    Pla-Rabes, Sergi
    Post, Eric
    Telling, Jon
    Stroud, David A.
    Whiteford, Erika J.
    Yallop, Marian L.
    Yde, Jacob C.
    The Arctic in the Twenty-First Century: Changing Biogeochemical Linkages across a Paraglacial Landscape of Greenland2017In: BioScience, ISSN 0006-3568, E-ISSN 1525-3244, Vol. 67, no 2, p. 118-133Article in journal (Refereed)
    Abstract [en]

    The Kangerlussuaq area of southwest Greenland encompasses diverse ecological, geomorphic, and climate gradients that function over a range of spatial and temporal scales. Ecosystems range from the microbial communities on the ice sheet and moisture-stressed terrestrial vegetation (and their associated herbivores) to freshwater and oligosaline lakes. These ecosystems are linked by a dynamic glacio-fluvial-aeolian geomorphic system that transports water, geological material, organic carbon and nutrients from the glacier surface to adjacent terrestrial and aquatic systems. This paraglacial system is now subject to substantial change because of rapid regional warming since 2000. Here, we describe changes in the eco-and geomorphic systems at a range of timescales and explore rapid future change in the links that integrate these systems. We highlight the importance of cross-system subsidies at the landscape scale and, importantly, how these might change in the near future as the Arctic is expected to continue to warm.

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  • 2. Anderson, N.J.
    et al.
    Appleby, P.G.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Renberg, I.
    Conley, D.J.
    Fritz, S.C.
    Jones, V.J.
    Whiteford, E.J.
    Yang, H
    Landscape-Scale Variability of Organic Carbon Burial by SW Greenland Lakes2019In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 22, no 8, p. 1706-1720Article in journal (Refereed)
    Abstract [en]

    Lakes are a key feature of arctic landscapes and can be an important component of regional organic carbon (OC) budgets, but C burial rates are not well estimated. 210Pb-dated sediment cores and carbon and organic matter (as loss-on-ignition) content were used to estimate OC burial for 16 lakes in SW Greenland. Burial rates were corrected for sediment focusing using the 210Pb flux method. The study lakes span a range of water chemistries (conductivity range 25–3400 µS cm−1), areas (< 4–100 ha) and maximum depths (~ 10–50 m). The regional average focusing-corrected OC accumulation rate was ~ 2 g C m−2 y−1 prior to ~ 1950 and 3.6 g C m−2 y−1 after 1950. Among-lake variability in post-1950 OC AR was correlated with in-lake dissolved organic carbon concentration, conductivity, altitude and location along the fjord. Twelve lakes showed an increase in mean OC AR over the analyzed time period, ~ 1880–2000; as the study area was cooling until recently, this increase is probably attributable to other global change processes, for example, altered inputs of N or P. There are ~ 20,000 lakes in the study area ranging from ~ 1 ha to more than 130 km2, although over 83% of lakes are less than 10 ha. Extrapolating the mean post-1950 OC AR (3.6 g C m−2 y−1) to all lakes larger than 1000 ha and applying a lower rate of ~ 2 g C m−2 y−1 to large lakes (> 1000 ha) suggests a regional annual lake OC burial rate of ~ 10.14 × 109 g C y−1 post 1950. Given the low C content of soils in this area, lakes represent a substantial regional C store.

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  • 3.
    Bishop, J. L.
    et al.
    Carl Sagan Center, SETI Institute, CA, Mountain View, United States; Space Science and Astrobiology, NASA Ames Research Center, CA, Moffett Field, United States.
    Yeşilbaş, Merve
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Carl Sagan Center, SETI Institute, Mountain View, CA, USA.
    Hinman, N. W.
    Department of Geosciences, University of Montana, MT, Missoula, United States.
    Burton, Z. F. M.
    Department of Geological Sciences, Stanford University, CA, Stanford, United States.
    Englert, P. A. J.
    Hawai'i Institute of Geophysics and Planetology, University of Hawai'i at Mānoa, HI, Honolulu, United States.
    Toner, J. D.
    Department of Earth and Space Sciences, University of Washington, WA, Seattle, United States.
    McEwen, A. S.
    Lunar and Planetary Laboratory, University of Arizona, AZ, Tucson, United States.
    Gulick, V.C.
    Carl Sagan Center, SETI Institute, CA, Mountain View, United States; Space Science and Astrobiology, NASA Ames Research Center, CA, Moffett Field, United States.
    Gibson, E. K.
    Astromaterials Research and Exploration Science, NASA Johnson Space Center, TX, Houston, United States.
    Koeberl, C.
    Department of Lithospheric Research, University of Vienna, Vienna, Austria.
    Martian subsurface cryosalt expansion and collapse as trigger for landslides2021In: Science Advances, E-ISSN 2375-2548, Vol. 7, no 6, article id eabe4459Article in journal (Refereed)
    Abstract [en]

    On Mars, seasonal martian flow features known as recurring slope lineae (RSL) are prevalent on sun-facing slopes and are associated with salts. On Earth, subsurface interactions of gypsum with chlorides and oxychlorine salts wreak havoc: instigating sinkholes, cave collapse, debris flows, and upheave. Here, we illustrate (i) the disruptive potential of sulfate-chloride reactions in laboratory soil crust experiments, (ii) the formation of thin films of mixed ice-liquid water “slush” at −40° to −20°C on salty Mars analog grains, (iii) how mixtures of sulfates and chlorine salts affect their solubilities in low-temperature environments, and (iv) how these salt brines could be contributing to RSL formation on Mars. Our results demonstrate that interactions of sulfates and chlorine salts in fine-grained soils on Mars could absorb water, expand, deliquesce, cause subsidence, form crusts, disrupt surfaces, and ultimately produce landslides after dust loading on these unstable surfaces.

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  • 4. Blackburn, M.
    et al.
    Ledesma, Jose L. J.
    Näsholm, Torgny
    Laudon, Hjalmar
    Sponseller, Ryan A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Evaluating hillslope and riparian contributions to dissolved nitrogen (N) export from a boreal forest catchment2017In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, no 2, p. 324-339Article in journal (Refereed)
    Abstract [en]

    Catchment science has long held that the chemistry of small streams reflects the landscapes they drain. However, understanding the contribution of different landscape units to stream chemistry remains a challenge which frequently limits our understanding of export dynamics. For limiting nutrients such as nitrogen (N), an implicit assumption is that the most spatially extensive landscape units (e.g., uplands) act as the primary sources to surface waters, while near-stream zones function more often as sinks. These assumptions, based largely on studies in high-gradient systems or in regions with elevated inputs of anthropogenic N, may not apply to low-gradient, nutrient-poor, and peat-rich catchments characteristic of many northern ecosystems. We quantified patterns of N mobilization along a hillslope transect in a northern boreal catchment to assess the extent to which organic matter-rich riparian soils regulate the flux of N to streams. Contrary to the prevailing view of riparian functioning, we found that near-stream, organic soils supported concentrations and fluxes of ammonium (NH4+) and dissolved organic nitrogen that were much higher than the contributing upslope forest soils. These results suggest that stream N chemistry is connected to N mobilization and mineralization within the riparian zone rather than the wider landscape. Results further suggest that water table fluctuation in near-surface riparian soils may promote elevated rates of net N mineralization in these landscapes.

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  • 5. Buckland, Paul C.
    et al.
    Panagiotakopulu, Eva
    University of Edinburgh, Scotland.
    Skidmore, Peter
    Snæsdóttir, Mjöll
    Institute of Archaeology, Iceland.
    Buckland, Philip I.
    Umeå University, Faculty of Arts, Archaeology and Sami Studies, Environmental Archaeology Lab.
    Insect faunas from Stóraborg, a farm mound in Southern Iceland2004Report (Other academic)
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  • 6.
    Buckland, Philip
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Lessons from extinctions2017In: Wood Wise, p. 22-27Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Many beetles are very good at colonising new areas when changes in the landscape open up new possibilities. Equally, they are highly susceptible to local extinction in the face of landscape scale changes in their environment.

  • 7.
    Buckland, Philip I.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab. Umeå University, Faculty of Arts, Humlab.
    The Bugs Coleopteran Ecology Package (BugsCEP) database: 1000 sites and half a million fossils later2014In: Quaternary International, ISSN 1040-6182, E-ISSN 1873-4553, Vol. 341, p. 272-282Article in journal (Refereed)
    Abstract [en]

    The Bugs database project started in the late 1980s as what would now be considered a relatively simple system, albeit advanced for its time, linking fossil beetle species lists to modern habitat and distribution information. Since then, Bugs has grown into a complex database of fossils records, habitat and distribution data, dating and climate reference data wrapped into an advanced software analysis package. At the time of writing, the database contains raw data and metadata for 1124 sites, and Russell Coope directly contributed to the analysis of over 154 (14%) of them, some 98790 identifications published in 231 publications. Such quantifications are infeasible without databases, and the analytical power of combining a database of modern and fossil insects with analysis tools is potentially immense for numerous areas of science ranging from conservation to Quaternary geology.

    BugsCEP, The Bugs Coleopteran Ecology Package, is the latest incarnation of the Bugs database project. Released in 2007, the database is continually added too and is available for free download from http://www.bugscep.com. The software tools include quantitative habitat reconstruction and visualisation, correlation matrices, MCR climate reconstruction, searching by habitat and retrieving, among other things, a list of taxa known from the selected habitat types. It also provides a system for entering, storing and managing palaeoentomological data as well as a number of expert system like reporting facilities.

    Work is underway to create an online version of BugsCEP, implemented through the Strategic Environmental Archaeology Database (SEAD) project (http://www.sead.se). The aim is to provide more direct access to the latest data, a community orientated updating system, and integration with other proxy data. Eventually, the tools available in the offline BugsCEP will be duplicated and Bugs will be entirely in the web.

    This paper summarises aspects of the current scope, capabilities and applications of the BugsCEP database and software, with special reference to and quantifications of the contributions of Russell Coope to the field of palaeoentomology as represented in the database. The paper also serves to illustrate the potential for the use of BugsCEP in biographical studies, and discusses some of the issues relating to the use of large scale sources of quantitative data.

    All datasets used in this article are available through the current version of BugsCEP available at http://www.bugscep.com.

  • 8.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab. Umeå University, Faculty of Arts, Humlab.
    Buckland, Paul C.
    BugsCEP, an entomological database twenty-five years on2014In: Antenna (Journal of the Royal Entomological Society), ISSN 0140-1890, Vol. 38, no 1, p. 21-28Article in journal (Refereed)
  • 9.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Buckland, Paul C.
    Species found as fossils in Quaternary sediments2018In: Checklist of beetles of the British Isles: with a chapter on fossil beetles / [ed] Andrew G. Duff, Iver: Pemberley Books , 2018, 3, p. 171-174Chapter in book (Other academic)
  • 10.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Buckland, Paul C.
    Olsson, Fredrik
    Paleoentomology: insects and other arthropods in environmental archaeology2018In: Encyclopedia of global archaeology / [ed] Claire Smith, Cham: Springer, 2018, 2Chapter in book (Refereed)
    Abstract [en]

    Insects are the most diverse group of animals on the planet and as such are present in a wider variety of habitats than most other complex organisms. This diversity, in addition to a long evolutionary history (Grimaldi and Engel 2005), and together with a propensity to be preserved in both desiccating and anaerobic environments, has provided an excellent tool for the reconstruction of both Quaternary and more immediate archaeological environments. Insect remains often provide proxy environmental information on the immediate context from which the fossils are derived, and as such may be either complementary to the more regional picture provided by palynology or indicate site conditions, such as levels of hygiene and evidence of trading connections, which are rarely available from any other palaeoecological source. They therefore provide information on a broad range of habitats and conditions, on- and off-site, and in addition, in appropriate contexts, also climate. Processing of samples is essentially simple, requiring readily available materials, yet is time consuming, and identification of the usually disarticulated fragments (sclerites) requires diligence and patience and access to well-curated reference collections. Fortunately, abundant literature, computer software, and database tools now exist to aid in their interpretation.

  • 11.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Eriksson, Erik J.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Palm, Fredrik
    Umeå University, Faculty of Arts, Humlab.
    SEAD - The Strategic Environmental Archaeology Database: Progress Report Spring 20142014Report (Other academic)
    Abstract [en]

    This report provides an overview of the progress and results of the VR:KFI infrastructure projects 2007-7494 and (825-)2010-5976. It should be considered as a status report in an on-going long-term research infrastructure development project.

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    SEAD - Progress Report Spring 2014
  • 12.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Linderholm, Johan
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Östman, Sofi
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Samuel, Ericson
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Wallin, Jan-Erik
    Pollenlaboratoriet i Umeå AB.
    Engelmark, Roger
    Environmental archaeological analysis from the archaeological excavations at Ørland kampflybase, Vik 70/1, Ørland, Sør-Trøndelag, Norway. 2015-20162017Report (Other academic)
    Abstract [en]

    A total of 322 bulk samples, 267 bulk subsamples and 1632 survey samples from the excavation of Iron Age settlements at Ørland, Vik, Sør-Trondelag, were analysed at the Environmental Archaeology Laboratory (MAL) at Umeå University. The overall aim of these analyses was to look for evidence which could help identify possible prehistoric activity areas, understand building functions and divisions, and shed light on land management around the farmsteads.

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  • 13.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Sjölander, Mattias
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Blombocken avslöjar forntiden2017In: Populär arkeologi, ISSN 0281-014X, no 5, p. 28-31Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Databaser. Fossila insekter och förkolnade fröer kan ge mycket information om de miljöer som människor har levt i och kan liksom annan biologisk information tjäna arkeologin.

  • 14.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Wallin, Jan-Erik
    Pollenlaboratoriet i Umeå AB.
    Pollen analysis of samples from the defensive ditch (vollgrav) at Site FO4 Klypen-Øst, Follobanen, Oslo2017Report (Other academic)
    Abstract [en]

    Nine samples were submitted for pollen analyses from three profiles from the "Vollgrav"defensive ditch feature, at the Follobanen FO4 Klypen-Øst excavation in Oslo. These samples were investigated with respect to their pollen contents and, in a separate investigation, soil micromorphology. The micromorphological methods and results are described in detail in a separate report from Richard Macphail (2016). Where relevant, these findings are commented on with respect to the other analysis results below.

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  • 15.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Östman, Sofi
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Wallin, Jan-Erik
    Pollenlaboratoriet i Umeå AB.
    Samuel, Ericson
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Linderholm, Johan
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Pollen, plant macrofossil and geoarchaeological analyses of profile 11632, Follobanen FO3, Oslo2017Report (Other academic)
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  • 16.
    Buckland, Philip
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Wallin, Jan-Erik
    Pollenlaboratoriet i Umeå AB.
    Pollenanalys från Rörbäcksnäs, Sälen, Dalarna2017Report (Other academic)
    Abstract [sv]

    Miljöarkeologiska Laboratoriet anlitades för att undersöka ett flertal torvmossar innanför föreslagna alternativa vägkorridorer i området nordöst om byn Rörbäcksnäs i Malung-Sälens kommun, Dalarna. Målen var att 1) undersöka den arkeologiska potentialen av våtmarkssediment som skulle förstöras av det föreslagna vägbygget och 2) utföra analyser på ett urval av materialet om det bedömdes vara tillräckligt välbevarat och av vetenskapligt intresse för området.

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  • 17. Cael, B. B.
    et al.
    Seekell, David A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The size-distribution of Earth's lakes2016In: Scientific Reports, E-ISSN 2045-2322, Vol. 6, article id 29633Article in journal (Refereed)
    Abstract [en]

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth's lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas >= 8.5 km(2) are power-law distributed with a tail exponent (T = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (T = 2.05; d = 4/3). Lakes <8.5 km(2) are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales.

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  • 18.
    Cael, B.B.
    et al.
    National Oceanography Centre, Southampton, United Kingdom.
    Biggs, Jeremy
    Freshwater Habitats Trust, Oxford, United Kingdom.
    Seekell, David A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The size-distribution of earth's lakes and ponds: limits to power-law behavior2022In: Frontiers in Environmental Science, E-ISSN 2296-665X, Vol. 10, article id 888735Article in journal (Refereed)
    Abstract [en]

    Global-scale characterizations of Earth's lakes and ponds assume their surface areas are power-law distributed across the full size range. However, empirical power-laws only hold across finite ranges of scales. In this paper, we synthesize evidence for upper and lower limits to power-law behavior in lake and pond size-distributions. We find support for the power-law assumption in general. We also find strong evidence for a lower limit to this power-law behavior, although the specific value for this limit is highly variable (0.001–1 km2), corresponding to orders of magnitude differences of the total number of lakes and ponds. The exact mechanisms that break the power-law at this limit are unknown. The power-law extends to the size of Earth's largest lake. There is inconsistent evidence for an upper limit at regional-scales. Explaining variations in these limits stands to improve the accuracy of global lake characterizations and shed light on the specific mechanism responsible for forming and breaking lake power-law distributions.

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  • 19.
    Cunningham, Laura
    et al.
    Umeå University, Faculty of Science and Technology. Climate Impacts Research Centre (CIRC), Umeå University, 98107 Abisko, Sweden.
    Vogel, Hendrik
    Nowaczyk, Norbert
    Wennrich, Volker
    Juschus, Olaf
    Persson, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rosen, Peter
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Climate Impacts Research Centre (CIRC), Umeå University, 98107 Abisko, Sweden.
    Climatic variability during the last interglacial inferred from geochemical proxies in the Lake El'gygytgyn sediment record2013In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 386, p. 408-414Article in journal (Refereed)
    Abstract [en]

    The Last Interglacial Period (LIP) is often regarded as a good analogue for potential climatic conditions under predicted global warming scenarios. Despite this, there is still debate over the nature, duration and frequency of climatic changes during this period. One particularly contentious issue has been the apparent evidence of climatic instability identified in many marine cores but seemingly lacking from many terrestrial archives, especially within the Arctic, a key region for global climate change research. In this paper, geochemical records from Lake El'gygytgyn, north-eastern Russia, are used to infer past climatic changes during the LIP from within the high Arctic. With a sampling resolution of similar to 20-similar to 90 years, these records offer the potential for detailed, high-resolution palaeoclimate reconstruction. This study shows that the LIP commenced in central Chukotka similar to 129 thousand years ago (ka), with the warmest climatic conditions occurring between similar to 128 and 127 ka before being interrupted by a short-lived cold reversal. Mild climatic conditions then persisted until similar to 122 ka when a marked reduction in the sedimentation rate suggests a decrease in precipitation. A further climatic deterioration at similar to 118 ka marks the return to glacial conditions. This study highlights the value of incorporating several geochemical proxies when inferring past climatic conditions, thus providing the potential to identify signals related to environmental change within the catchment. We also demonstrate the importance of considering how changes in sedimentation rate influence proxy records, in order to develop robust palaeoenvironmental reconstructions. (C) 2013 Elsevier B.V. All rights reserved.

  • 20.
    Ekeberg, Jonas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Swedish Institute of Space Physics, P.O. Box 812, SE-981 28 Kiruna, Sweden.
    Wannberg, Gudmund
    Swedish Institute of Space Physics, P.O. Box 812, SE-981 28 Kiruna, Sweden.
    Eliasson, Lars
    Swedish Institute of Space Physics, P.O. Box 812, SE-981 28 Kiruna, Sweden.
    Häggström, Ingemar
    EISCAT Scientific Association, P.O. Box 812, SE-981 28 Kiruna, Sweden.
    Soliton-induced spectrally uniform ion line power enhancements at the ionospheric F region peak2012In: Earth Planets and Space, ISSN 1343-8832, E-ISSN 1880-5981, Vol. 64, no 7, p. 605-611Article in journal (Refereed)
    Abstract [en]

    We present European incoherent scatter (EISCAT) observations of spectrally uniform ion line power enhancements (SUIPE), where the up- and downshifted shoulder and the spectral valley between them are enhanced simultaneously and equally. We have identified 48 cases of this type of ion line enhancements in data from the EISCAT Svalbard radar taken during the International Polar Year (extending from March 2007 to the end of February 2008). The SUIPEs are observed at altitudes between 210 km and 280 km with a standard deviation of 9% of the average occurrence height 230 km. The power enhancements are one order of magnitude above the thermal level. The SUIPEs occur at the ionospheric F region peak with 85% of the cases located within 10 km of the peak. The occurrence shows a clear preference for magnetically disturbed conditions, with the likelihood of occurrence increasing with increasing K index. A majority of the events occur in the magnetic evening to pre-midnight sector.

  • 21.
    Ekström, Victoria
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Klimatneutralitet och biologisk mångfald: Hur biologisk mångfald kan påverkas av kommunala insatser2023Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
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  • 22.
    Fabrikant, Sara Irina
    et al.
    Department of Geography, University of Zürich.
    Kübler, Isabella
    Department of Geography, University of Zürich.
    Richter, Kai-Florian
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    How does the visualization of uncertainty influence decision making with hazard prediction maps?2017Manuscript (preprint) (Other academic)
    Abstract [en]

    A wealth of design strategies has been proposed by an interdisciplinary scientific community to visually communicate data uncertainty in maps, with the aim to support spatio-temporal decision-making under uncertainty (MacEachren et al., 2012). However, very few researchers have looked at whether and how uncertainty depictions might influence people’s reasoning processes and decision making outcomes, especially in problem contexts for which uncertainty truly matters, i.e., in life-threatening situations, or for dilemmatic decisions. 

    We report on a map-based multi-criteria decision making study where participants (N=35) were asked to imagine purchasing a house shown on map stimuli inspired by Swiss National hazard prediction maps (SFOEN, 2016). These area-classed maps show the probability and intensity of natural disasters occurring in areas with varying danger levels in a pre-defined color scheme (i.e., red=high, blue=moderate, and yellow=low danger). Current hazard prediction maps do not depict prediction uncertainties, even though suggestions have been proposed in the cartographic literature (Kunz and Hurni, 2011). However, because there are uncertainties associated with the areal extent of the classed danger zones, we modified the zonal boundaries to show this locational uncertainty using the visual variables color value, focus, and texture, as suggested by prior empirical research (MacEachren, 2012). In a within-subject design, participants were repeatedly asked to decide which house they wished to buy, given varying house location characteristics, and respective purchase price information. The houses were depicted on a series of hazard prediction maps showing an area unknown to participants, with/without data uncertainty depicted. The maps showing uncertainty varied in the visual variables (i.e., color value|focus|texture) used to convey the locational uncertainty of the zonal boundaries. We recorded participants’ house selections, response times, and eye movements during the experiment. The task asked for participants’ preferences; there were no right or wrong answers. 

    As hypothesized, our results show that participants’ decision making outcomes were indeed influenced by the depicted uncertainty information. Participants decided to buy different houses, as they weighted selection criteria differently, depending on whether uncertainty was shown on the map or not. We thus provide rare evidence on how uncertainty and the type of uncertainty visualization (i.e., varying color value, focus, or texture) can influence people’s reasoning to arrive at a complex, multi-criteria-based decision. We also find that participants’ individual differences with respect to their risk taking behavior tested with a standardised questionnaire influences their decision making. Risk takers underestimate the dangers of natural hazards when prediction uncertainties are depicted. 

    With this unique study we are able to shed additional light on how people use visualized uncertainty information to make complex map-based decisions. Echoing Hegarty et al.'s (2016) findings, we again demonstrate that not only display design characteristics are relevant for map-based reasoning and decision making outcomes, but also the decision makers’ individual background, and the map-based decision-making task and context. 

    References: Hegarty, M., Friedman, A., Boone, A.P., Barrett, T.J. (2016). Where Are You? The Effect of Uncertainty and Its Visual Representation on Location Judgments in GPS-Like Displays. Journal of Experimental Psychology, Applied, DOI: 10.1037/xap0000103. Kunz, M. and Hurni, L. (2011). How to Enhance Cartographic Visualisations of Natural Hazards Assessment Results. The Cartographic Journal, 48(1): 60-71. MacEachren, A. M., Roth, R. E., O'Brien, J., Li, B., Swingley, D., Gahegan, M. (2012). Visual Semiotics & Uncertainty Visualization: An Empirical Study. IEEE Transactions on Visualization and Computer Graphics, 18(12): 2496-2505. Swiss Federal Office for the Environment (SFOEN). Gefahrenkarten, Intensitätskarten und Gefahrenhinweiskarten. (Natural Hazard Maps), http://www.bafu.admin.ch/naturgefahren/14186/14801/15746/ (not available in English, accessed Oct. 2016).

  • 23. Faucherre, Samuel
    et al.
    Jørgensen, Christian Juncher
    Blok, Daan
    Weiss, Niels
    Siewert, Matthias Benjamin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Physical Geography, Stockholm University,Stockholm, Sweden.
    Bang-Andreasen, Toke
    Hugelius, Gustaf
    Kuhry, Peter
    Elberling, Bo
    Short and Long-Term Controls on Active Layer and Permafrost Carbon Turnover Across the Arctic2018In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 123, no 2, p. 372-390Article in journal (Refereed)
    Abstract [en]

    Decomposition of soil organic matter (SOM) in permafrost terrain and the production of greenhouse gases is a key factor for understanding climate change-carbon feedbacks. Previous studies have shown that SOM decomposition is mostly controlled by soil temperature, soil moisture, and carbon-nitrogen ratio (C:N). However, focus has generally been on site-specific processes and little is known about variations in the controls on SOM decomposition across Arctic sites. For assessing SOM decomposition, we retrieved 241 samples from 101 soil profiles across three contrasting Arctic regions and incubated them in the laboratory under aerobic conditions. We assessed soil carbon losses (C-loss) five times during a 1year incubation. The incubated material consisted of near-surface active layer (AL(NS)), subsurface active layer (AL(SS)), peat, and permafrost samples. Samples were analyzed for carbon, nitrogen, water content, C-13, N-15, and dry bulk density (DBD). While no significant differences were observed between total AL(SS) and permafrost C-loss over 1year incubation (2.32.4% and 2.51.5% C-loss, respectively), AL(NS) samples showed higher C-loss (7.94.2%). DBD was the best explanatory parameter for active layer C-loss across sites. Additionally, results of permafrost samples show that C:N ratio can be used to characterize initial C-loss between sites. This data set on the influence of abiotic parameter on microbial SOM decomposition can improve model simulations of Arctic soil CO2 production by providing representative mean values of CO2 production rates and identifying standard parameters or proxies for upscaling potential CO2 production from site to regional scales.

  • 24.
    Guédron, Stéphane
    et al.
    Université Grenoble Alpes, Institut des Sciences de la Terre, Institut de Recherche pour le Développement, Grenoble, France.
    Delaere, Christophe
    Centre de Recherches en Archéologie et Patrimoine, Université libre de Bruxelles, Brussels, Belgium.
    Fritz, Sherilyn C.
    Department of Earth and Atmospheric Sciences and School of Biological Sciences, University of Nebraska - Lincoln, Lincoln, NE 68588.
    Tolu, Julie
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland; ETH Zürich, Zürich, Switzerland.
    Sabatier, Pierre
    Univ. Savoie Mont Blanc, Centre National de la Recherche Scientifiquel, Environnements Dynamiques et Territoires de la Montagne, Chambéry, France.
    Devel, Anne-Lise
    Univ. Savoie Mont Blanc, Centre National de la Recherche Scientifiquel, Environnements Dynamiques et Territoires de la Montagne, Chambéry, France.
    Heredia, Carlos
    Laboratorio de Hidroquímica - Instituto de Investigaciones Químicas - Universidad Mayor de San Andres, Campus Universitario de Cota Cotacasilla 3161, La Paz, Bolivia.
    Vérin, Claire
    Université Grenoble Alpes, Institut des Sciences de la Terre, Institut de Recherche pour le Développement, Grenoble, France.
    Alves, Eduardo Q.
    Royal Belgian Institute of Natural Sciences, Bruxelles, Belgium.
    Baker, Paul A.
    Division of Earth and Climate Sciences, Duke University, Durham, United Kingdom.
    Holocene variations in Lake Titicaca water level and their implications for sociopolitical developments in the central Andes2023In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 120, no 2, article id 2215882120Article in journal (Refereed)
    Abstract [en]

    Holocene climate in the high tropical Andes was characterized by both gradual and abrupt changes, which disrupted the hydrological cycle and impacted landscapes and societies. High-resolution paleoenvironmental records are essential to contextualize archaeological data and to evaluate the sociopolitical response of ancient societies to environmental variability. Middle-to-Late Holocene water levels in Lake Titicaca were reevaluated through a transfer function model based on measurements of organic carbon stable isotopes, combined with high-resolution profiles of other geochemical variables and paleoshoreline indicators. Our reconstruction indicates that following a prolonged low stand during the Middle Holocene (4000 to 2400 BCE), lake level rose rapidly ~15 m by 1800 BCE, and then increased another 3 to 6 m in a series of steps, attaining the highest values after ~1600 CE. The largest lake-level increases coincided with major sociopolitical changes reported by archaeologists. In particular, at the end of the Formative Period (500 CE), a major lake-level rise inundated large shoreline areas and forced populations to migrate to higher elevation, likely contributing to the emergence of the Tiwanaku culture.

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  • 25. Hey, David
    et al.
    Buckland, Paul C.
    Buckland, Philip I.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Gearey, Ben
    Department of Archaeology, University College Cork, UK.
    O'Neill, Richard
    Tyers, Ian
    The Conisbrough Estate and the southern boundary of Northumbria: environmental and archaeological evidence from a late sixth-/early seventh-century structure and a later enclosure ditch at Conisbrough, South Yorkshire2023In: Anglo-Saxon studies in archaeology and history 23 / [ed] Helena Hamerow, Oxford: Archaeopress, 2023, 23, p. 167-205Chapter in book (Refereed)
    Abstract [en]

    Excavations close to the Anglo-Saxon church at Conisbrough, South Yorkshire, UK, revealed a plank-walled construction dated by dendrochronology to the late sixth or early seventh century. It is suggested that this formed part of a stock pond for fish, associated with an elite residence to which a partly surviving Anglo-Saxon church incorporating Northumbrian features is related. Environmental evidence shows a neglected wood pasture landscape associated with the infilling of a ditch which cuts through the structure. This is likely to be related either to a burh centred on the church or to a deer park established shortly after the Norman Conquest and associated with the castle.

  • 26.
    Holmgren, Bror
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Soil organic carbon pools of the Torneträsk catchment area: The importance of soil depth and stone and boulder content for carbon inventories in formerly glaciated subarctic soils2013Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    High latitude soils are estimated to store a considerable part of the global pool of soil organic carbon (SOC). Studies of global and regional SOC pools have estimated total inventories in northern Sweden’s subarctic region to fall within 10-50 kg m-2. However, correction factors for stone and boulder content of soils are often overlooked in SOC-studies and soil profiles are commonly normalized to a depth of 1 m, which can result in substantial overestimates of the SOC pool if a large part of the soil volume is occupied by stones/boulders or if the soil depth is shallower than 1 m. This study was performed to quantify SOC in soils of the Torneträsk catchment area using detailed measures of soil depth and stone/boulder contents. Two non-destructive sampling methods, ground penetrating radar (GPR) and rod penetration, were used to measure soil depth and stone and boulder content in the catchment area. Results show that average soil depth (n = 52344) varied between 0.95 – 2.14 m depending on elevation and the average mire depth was 0.63 m. Stone and boulder content of the soil was estimated to 49 – 68 % depending on elevation. The results were added to existing carbon and soil density data from the Torneträsk catchment area and total SOC inventories were calculated to 6.8 – 13.1 kg m-2. The results of this study indicate that previous studies on regional and global scale may have overestimated the SOC pools in the subarctic regions of northern Sweden.

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  • 27.
    Holmgren, Bror
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Tracing the source of colourless carbon in an arctic lake on SW Greenland: Insights of organic matter origin from hydrogen isotope analyses of samples prepared using steam equilibration2016Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    Lakes play an important role in the global carbon (C) cycle as they process carbon from terrestrial (allochthonous) and within lake (autochthonous) sources and may store C over long periods of time. Some arctic lakes contain high concentrations of dissolved organic carbon (DOC) that does not absorb light and thus remains colourless. The origin of this DOC remains unknown, but the sediment of these lakes have been suggested to accumulate primarily autochthonous (algal) C. I developed an experimental chamber for hydrogen (H) isotope pre-treatments and applied a novel H isotope tracing approach to determine the origin of the DOC and sediment C of a lake on SW Greenland known to contain colourless DOC. I hypothesized that autochthonous C was the prime source of DOC and sediment C, in line with previous theories. Analyses of algae and soil samples from the catchment revealed that local allochthonous and autochthonous C sources had a δ2H composition of -139 ‰ and -209 ‰, respectively. In contrast to my hypothesis, the analysed DOC had a mean δ2H isotopic composition of -147 ‰ indicating a dominance (ca 80-90 %) of allochthonous C. Similarly, the sediment had a mean δ2H isotopic composition of -155 ‰, suggesting that about 84 % of the C accumulating in the sediment was derived from terrestrial sources. The terrestrial origin was supported by field observations of high DOC seepage water (up to 70 mg L-1) with uncharacteristically low light absorption values entering the lake during high precipitation events. My results indicate that terrestrial processes are fundamental C sources for arctic lakes, even in regions with very low precipitation.

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  • 28.
    Hotchkiss, E. R.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hall, R. O., Jr.
    Sponseller, R. A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Butman, D.
    Klaminder, J.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Laudon, H.
    Rosvall, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Karlsson, J.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sources of and processes controlling CO2 emissions change with the size of streams and rivers2015In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 8, no 9, p. 696-699Article in journal (Refereed)
    Abstract [en]

    Carbon dioxide (CO2) evasion from streams and rivers to the atmosphere represents a substantial flux in the global carbon cycle(1-3). The proportions of CO2 emitted from streams and rivers that come from terrestrially derived CO2 or from CO2 produced within freshwater ecosystems through aquatic metabolism are not well quantified. Here we estimated CO2 emissions from running waters in the contiguous United States, based on freshwater chemical and physical characteristics and modelled gas transfer velocities at 1463 United States Geological Survey monitoring sites. We then assessed CO2 production from aquatic metabolism, compiled from previously published measurements of net ecosystem production from 187 streams and rivers across the contiguous United States. We find that CO2 produced by aquatic metabolism contributes about 28% of CO2 evasion from streams and rivers with flows between 0.0001 and 19,000 m(3) s(-1). We mathematically modelled CO2 flux from groundwater into running waters along a stream-river continuum to evaluate the relationship between stream size and CO2 source. Terrestrially derived CO2 dominates emissions from small streams, and the percentage of CO2 emissions from aquatic metabolism increases with stream size. We suggest that the relative role of rivers as conduits for terrestrial CO2 efflux and as reactors mineralizing terrestrial organic carbon is a function of their size and connectivity with landscapes.

  • 29.
    Hotchkiss, Erin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Program in Ecology and Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, USA.
    Hall, R. O., Jr.
    Baker, M. A.
    Rosi-Marshall, E. J.
    Tank, J. L.
    Modeling priming effects on microbial consumption of dissolved organic carbon in rivers2014In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 119, no 5, p. 982-995Article in journal (Refereed)
    Abstract [en]

    Rivers receive and process large quantities of terrestrial dissolved organic carbon (DOC). Biologically available (unstable) DOC leached from primary producers may stimulate (i.e., prime) the consumption of more stable terrestrially derived DOC by heterotrophic microbes. We measured microbial DOC consumption (i.e., decay rates) from contrasting C sources in 10 rivers in the western and Midwestern United States using short-term bioassays of river water, soil and algal leachates, glucose, and commercial humate. We added inorganic nutrients (ammonium and phosphorus) to a subset of bioassays. We also amended a subset of river, soil, and commercial humate bioassays with glucose or algal leachates to test the hypothesis that unstable DOC primes consumption of more stable DOC. We used prior measurements of source-specific DOC bioavailability, linked with a Bayesian process model, to estimate means and posterior probability distributions for source-specific DOC decay rates in multisource bioassays. Modeled priming effects ranged from a -130 to +370% change in more stable DOC decay when incubated with unstable DOC. Glucose increased modeled river DOC decay by an average of 87% among all rivers. Glucose and algal leachates increased soil leachate and commercial humate decay by an average of 25% above background rates. Inorganic nutrient additions did not have consistent effects on DOC decay, likely because most of the study rivers had high ambient background nutrients. Our results demonstrate that the priming effect can augment DOC decay in rivers. In addition, Bayesian models can be used to estimate mechanisms driving aquatic ecosystem processes that are difficult to measure directly.

  • 30.
    Jerand, Philip
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Klaminder, Jonatan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Linderholm, Johan
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    The legacy of ecological imperialism on soil fauna: implications for Arctic researchManuscript (preprint) (Other academic)
  • 31. Karlsson, Tomas
    et al.
    Hamrin, Maria
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nilsson, Hans
    Kullen, Anita
    Pitkänen, Timo
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Magnetic forces associated with bursty bulk flows in Earth's magnetotail2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 9, p. 3122-3128Article in journal (Refereed)
    Abstract [en]

    We present the first direct measurements of magnetic forces acting on bursty bulk flow plasma in the magnetotail. The magnetic forces are determined using Cluster multispacecraft measurements. We analyze 67 bursty bulk flow (BBF) events and show that the curvature part of the magnetic force is consistently positive, acting to accelerate the plasma toward Earth between approximately 10 and 20 R-E geocentrical distances, while the magnetic field pressure gradient increasingly brakes the plasma as it moves toward Earth. The net result is that the magnetic force accelerates the plasma at distances greater than approximately 14 R-E, while it acts to decelerate it within that distance. The magnetic force, together with the thermal pressure gradient force, will determine the dynamics of the BBFs as they propagate toward the near-Earth tail region. The determination of the former provides an important clue to the ultimate fate of BBFs in the inner magnetosphere.

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  • 32. Karnachuk, Olia V
    et al.
    Pimenov, Nikolay V
    Yusupov, Sandjar K
    Frank, Yulia A
    Kaksonen, Anna H
    Puhakka, Jaakko A
    Ivanov, Mikhail V
    Lindström, E Börje
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Tuovinen, Olli H
    Sulfate reduction potential in sediments in the Norilsk mining area, northern Siberia2005In: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 22, no 1-2, p. 11-25Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to characterize the distribution and activity of sulfate-reducing bacteria in tailings and sediments impacted by effluents from mining and smelting operations in the Norilsk area in northern Siberia. The Norilsk mining complex involves three smelter operations, a hydrometallurgical plant, and extensive tailings areas located in the permafrost zone. Sulfate reduction rates measured with a (35)SO(4)(2-) tracer technique under various in-situ conditions ranged from 0.05 to 30 nmol S cm(-3) day(-1). Acetate and glucose addition greatly stimulated sulfate reduction, whereas lactate had less effect. The most pronounced stimulation of sulfate reduction (6.5-fold) was observed with phosphate amendment. Most-probable-number (MPN) counts of sulfate-reducing bacteria in media with glucose, ethanol, lactate, and acetate as electron donors were generally highest at around 10(7) cells ml(-1). The actual MPN counts varied with the sample, electron donor, and incubation conditions (pH 7.2 vs. pH 3.5; 28 degrees C vs. 4 degrees C). Enrichment cultures of sulfate-reducing bacteria were established from a sample that showed the highest rate of sulfate reduction. After multiple serial transfers, the dominant sulfate-reducers were identified by fluorescence in situ hybridization using genus and group-specific 16S rRNA-targeted oligonucleotide probes. Desulfobulbus spp. prevailed in ethanol and lactate enrichments and the Desulfosarcina-Desulfococcus group dominated in acetate and benzoate enrichments. Psychrophilic Desulfotalea-Desulfofustis and moderately psychrophilic Desulforhopalus spp. were identified in enrichments incubated at 4 degrees C, but they were also found in mesophilic enrichments.

  • 33.
    Kashian, Alireza
    et al.
    Dept. of Infrastructure Engineering, University of Melbourne, Parkville, Australia.
    Rajabifard, Abbas
    Dept. of Infrastructure Engineering, University of Melbourne, Parkville, Australia.
    Chen, Yiqun
    Dept. of Infrastructure Engineering, University of Melbourne, Parkville, Australia.
    Richter, Kai-Florian
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    OSM POI Analyzer: A Platform for Assessing Position of POIs in OpenStreetMap2017In: ISPRS Geospatial Week 2017 / [ed] D. Li, J. Gong, B. Yang, H. Wu, L. Wu, Z. Gui, X. Cheng, H. Wu, S. Li, R. Lindenbergh, J. Boehm, M. Rutzinger, W. Yao, M. Weinmann, Z. Kang, K. Khoshelham, M. Peter, L. Díaz-Vilariño, W. Shi, B. Lu, H. Abdulmuttalib, M. R. Delavar, T. Balz, B. Osmanoglu, F. Rocca, U. Sörgel, J. Zhang, P. Li, S. Du, L. Zhao, X. Lin, K. Qin, C. Kang, X. Li, C. Chen, R. Li, G. Qiao, H. Wu, and C. Heipke, 2017, Vol. XLII-2/W7, p. 497-504Conference paper (Refereed)
    Abstract [en]

     In recent years, more and increased participation in Volunteered Geographical Information (VGI) projects provides enough data coverage for most places around the world for ordinary mapping and navigation purposes, however, the positional credibility of contributed data becomes more and more important to bring a long-term trust in VGI data. Today, it is hard to draw a definite traditional boundary between the authoritative map producers and the public map consumers and we observe that more and more volunteers are joining crowdsourcing activities for collecting geodata, which might result in higher rates of man-made mistakes in open map projects such as OpenStreetMap. While there are some methods for monitoring the accuracy and consistency of the created data, there is still a lack of advanced systems to automatically discover misplaced objects on the map. One feature type which is contributed daily to OSM is Point of Interest (POI). In order to understand how likely it is that a newly added POI represents a genuine real-world feature scientific means to calculate a probability of such a POI existing at that specific position is needed. This paper reports on a new analytic tool which dives into OSM data and finds co-existence patterns between one specific POI and its surrounding objects such as roads, parks and buildings. The platform uses a distance-based classification technique to find relationships among objects and tries to identify the high-frequency association patterns among each category of objects. Using such method, for each newly added POI, a probabilistic score would be generated, and the low scored POIs can be highlighted for editors for a manual check. The same scoring method can be used for existing registered POIs to check if they are located correctly. For a sample study, this paper reports on the evaluation of 800 pre-registered ATMs in Paris with associated scores to understand how outliers and fake entries could be detected automatically.

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  • 34. Khorasani, Sara
    et al.
    Panagiotakopulu, Eva
    Engelmark, Roger
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies.
    Ralston, Ian
    Late Holocene beetle assemblages and environmental change in Gammelhemmet, northern Sweden2015In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 44, no 2, p. 368-382Article in journal (Refereed)
    Abstract [en]

    Analysis of insect fossil remains retrieved from a bog close to the abandoned farm at Gammelhemmet, near Lycksele in Swedish Lapland, enabled the reconstruction of environmental changes at the site over the last 2500years. These results represent the first late Holocene palaeoentomological succession studied for insect remains in the Vasterbotten interior, and they provide new evidence for landscape change in the area. Around 2000years ago, at the end of the early Iron Age, disappearance of the tree and leaf litter fauna and an increase in aquatic species indicate the expansion of wetlands in the area. Patches of a multi-aged mixed woodland with a diverse assemblage of forest-dwelling beetles succeeded the wetland approximate to 1500years ago, at the beginning of the late Iron Age. A marked change to open and drier conditions, and the presence of species often found in grassland and cultivated ground took place during the post-Medieval period. Our evidence indicates drainage of the area prior to the 18th century, placing the initiation of agricultural activities in Gammelhemmet earlier than the documentary record. Our research shows the potential of the use of fossil insects for understanding environmental change and also human impact on the landscape, even of limited scale, from natural contexts.

  • 35.
    Kjær, Kurt H.
    et al.
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Winther Pedersen, Mikkel
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    De Sanctis, Bianca
    Department of Zoology, University of Cambridge, Cambridge, UK; Department of Genetics, University of Cambridge, Cambridge, UK.
    De Cahsan, Binia
    Section for Molecular Ecology and Evolution, The Globe Institute, Faculty of Health and Medical Sciences, Copenhagen, Denmark.
    Korneliussen, Thorfinn S.
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Michelsen, Christian S.
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
    Sand, Karina K.
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Jelavić, Stanislav
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark; Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, Université Gustave Eiffel, ISTerre, Grenoble, France.
    Ruter, Anthony H.
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Schmidt, Astrid M. A.
    Nordic Foundation for Development and Ecology (NORDECO), Copenhagen, Denmark; DIS Study Abroad in Scandinavia, University of Copenhagen, Copenhagen, Denmark.
    Kjeldsen, Kristian K.
    Department of Glaciology and Climate, Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
    Tesakov, Alexey S.
    Geological Institute, Russian Academy of Sciences, Moscow, Russia.
    Snowball, Ian
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Gosse, John C.
    Department of Earth and Environmental Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
    Alsos, Inger G.
    The Arctic University Museum of Norway, UiT—The Arctic University of Norway, Tromsø, Norway.
    Wang, Yucheng
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark; Department of Zoology, University of Cambridge, Cambridge, UK.
    Dockter, Christoph
    Carlsberg Research Laboratory, Copenhagen, Denmark.
    Rasmussen, Magnus
    Carlsberg Research Laboratory, Copenhagen, Denmark.
    Jørgensen, Morten E.
    Carlsberg Research Laboratory, Copenhagen, Denmark.
    Skadhauge, Birgitte
    Carlsberg Research Laboratory, Copenhagen, Denmark.
    Prohaska, Ana
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark; Department of Zoology, University of Cambridge, Cambridge, UK.
    Kristensen, Jeppe Å.
    Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, UK; Geological Survey of Denmark and Greenland, (GEUS), Copenhagen, Denmark.
    Bjerager, Morten
    Department of Geophysics and Sedimentary Basins, Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
    Allentoft, Morten E.
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark; Trace and Environmental DNA (TrEnD) Laboratory, School of Molecular and Life Sciences, Curtin University, Perth, Western Australia, Australia.
    Coissac, Eric
    The Arctic University Museum of Norway, UiT—The Arctic University of Norway, Tromsø, Norway; University of Grenoble-Alpes, Université Savoie Mont Blanc, CNRS, LECA, Grenoble, France.
    Rouillard, Alexandra
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark; Department of Geosciences, UiT—The Arctic University of Norway, Tromsø, Norway.
    Simakova, Alexandra
    Geological Institute, Russian Academy of Sciences, Moscow, Russia.
    Fernandez-Guerra, Antonio
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Bowler, Chris
    Institut de Biologie de l’Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM Université PSL, Paris, France.
    Macias-Fauria, Marc
    School of Geography and the Environment, University of Oxford, Oxford, UK.
    Vinner, Lasse
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Welch, John J.
    Department of Genetics, University of Cambridge, Cambridge, UK.
    Hidy, Alan J.
    Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA, USA.
    Sikora, Martin
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Collins, Matthew J.
    Department of Archaeology, University of Cambridge, Cambridge, UK; Section for GeoBiology, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Durbin, Richard
    Department of Genetics, University of Cambridge, Cambridge, UK.
    Larsen, Nicolaj K.
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark.
    Willerslev, Eske
    Lundbeck Foundation GeoGenetics Centre, Globe Institute, University of Copenhagen, Copenhagen, Denmark; Department of Zoology, University of Cambridge, Cambridge, UK; MARUM, University of Bremen, Bremen, Germany.
    A 2-million-year-old ecosystem in Greenland uncovered by environmental DNA2022In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 612, no 7939, p. 283-291Article in journal (Refereed)
    Abstract [en]

    Late Pliocene and Early Pleistocene epochs 3.6 to 0.8 million years ago1 had climates resembling those forecasted under future warming2. Palaeoclimatic records show strong polar amplification with mean annual temperatures of 11-19 °C above contemporary values3,4. The biological communities inhabiting the Arctic during this time remain poorly known because fossils are rare5. Here we report an ancient environmental DNA6 (eDNA) record describing the rich plant and animal assemblages of the Kap København Formation in North Greenland, dated to around two million years ago. The record shows an open boreal forest ecosystem with mixed vegetation of poplar, birch and thuja trees, as well as a variety of Arctic and boreal shrubs and herbs, many of which had not previously been detected at the site from macrofossil and pollen records. The DNA record confirms the presence of hare and mitochondrial DNA from animals including mastodons, reindeer, rodents and geese, all ancestral to their present-day and late Pleistocene relatives. The presence of marine species including horseshoe crab and green algae support a warmer climate than today. The reconstructed ecosystem has no modern analogue. The survival of such ancient eDNA probably relates to its binding to mineral surfaces. Our findings open new areas of genetic research, demonstrating that it is possible to track the ecology and evolution of biological communities from two million years ago using ancient eDNA.

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  • 36. Krickov, Ivan V.
    et al.
    Lim, Artem G.
    Manasypov, Rinat M.
    Loiko, Sergey V.
    Shirokova, Liudmila S.
    Kirpotin, Sergey N.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Pokrovsky, Oleg S.
    Riverine particulate C and N generated at the permafrost thaw front: case study of western Siberian rivers across a 1700km latitudinal transect2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 22, p. 6867-6884Article in journal (Refereed)
    Abstract [en]

    In contrast to numerous studies on the dynamics of dissolved (< 0.45 mu m) elements in permafrost-affected highlatitude rivers, very little is known of the behavior of river suspended (> 0.45 mu m) matter (RSM) in these regions. In order to test the effect of climate, permafrost and physiogeographical landscape parameters (bogs, forest and lake coverage of the watershed) on RSM and particulate C, N and P concentrations in river water, we sampled 33 small and medium-sized rivers (10-100 000 km(2) watershed) along a 1700 km N-S transect including both permafrost-affected and permafrost-free zones of the Western Siberian Lowland (WSL). The concentrations of C and N in RSM decreased with the increase in river watershed size, illustrating (i) the importance of organic debris in small rivers which drain peatlands and (ii) the role of mineral matter from bank abrasion in larger rivers. The presence of lakes in the watershed increased C and N but decreased P concentrations in the RSM. The C V N ratio in the RSM reflected the source from the deep soil horizon rather than surface soil horizon, similar to that of other Arctic rivers. This suggests the export of peat and mineral particles through suprapermafrost flow occurring at the base of the active layer. There was a maximum of both particulate C and N concentrations and export fluxes at the beginning of permafrost appearance, in the sporadic and discontinuous zone (62-64 degrees N). This presumably reflected the organic matter mobilization from newly thawed organic horizons in soils at the active latitudinal thawing front. The results suggest that a northward shift of permafrost boundaries and an increase in active layer thickness may increase particulate C and N export by WSL rivers to the Arctic Ocean by a factor of 2, while P export may remain unchanged. In contrast, within a long-term climate warming scenario, the disappearance of permafrost in the north, the drainage of lakes and transformation of bogs to forest may decrease C and N concentrations in RSM by 2 to 3 times.

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  • 37.
    Kullman, Leif
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Early postglacial appearance of tree species in northern Scandinavia: review and perspective2008In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 27, no 27-28, p. 2467-2472Article in journal (Refereed)
    Abstract [en]

    This paper reviews megafossil evidence for the first postglacial records of different tree species in northern Scandinavia. Betula pubescens coll. appeared at the Arctic coast of northern Norway by 16. 900 yr BR In addition, Betula Pubescens (14, 000 yr BP), Pinus sylvestris (11, 700 yr BP) and Picea abies (11, 000 yr BP) existed on early ice- free mountain peaks (nunataks) at different locations in the Scandes during the Lateglacial. Larix sibirica, currently not native to Fennoscandia, and several thermophilous broadleaved tree species were recorded in the earliest part of the Holocene. The conventional interpretation of pollen and macrofossil records from peat and sediment stratigraphies do not consider the Occurrence of the species mentioned above that early at these northern and high altitude sites. This very rapid arrival after the local deglaciation implies that the traditional model of far distant glacial refugial areas for tree species has to be challenged. The Current results are more compatible with a situation involving scattered "cryptic" refugia quite close to margin of the ice sheet at its full-glacial extension. This fits a more general pattern currently emerging on different continents. In general, "cryptic" refugia should be considered in connection with modelling extinction risks related to modern and possible future "climatic crises".

  • 38. Kylander, Malin E.
    et al.
    Martínez-Cortizas, A.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kaal, Joeri
    Sjöström, Jenny K.
    Hansson, Sophia V.
    Silva-Sánchez, Noemi
    Greenwood, Sarah L.
    Gallagher, Kerry
    Rydberg, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Mörth, Carl-Magnus
    Rauch, Sebastien
    Mineral dust as a driver of carbon accumulation in northern latitudes2018In: Scientific Reports, E-ISSN 2045-2322, Vol. 8, article id 6876Article in journal (Refereed)
    Abstract [en]

    Peatlands in northern latitudes sequester one third of the world's soil organic carbon. Mineral dusts can affect the primary productivity of terrestrial systems through nutrient transport but this process has not yet been documented in these peat-rich regions. Here we analysed organic and inorganic fractions of an 8900-year-old sequence from Store Mosse (the "Great Bog") in southern Sweden. Between 5420 and 4550 cal yr BP, we observe a seven-fold increase in net peat-accumulation rates corresponding to a maximum carbon-burial rate of 150 g C m-2 yr-1 - more than six times the global average. This high peat accumulation event occurs in parallel with a distinct change in the character of the dust deposited on the bog, which moves from being dominated by clay minerals to less weathered, phosphate and feldspar minerals. We hypothesize that this shift boosted nutrient input to the bog and stimulated ecosystem productivity. This study shows that diffuse sources and dust dynamics in northern temperate latitudes, often overlooked by the dust community in favour of arid and semi-arid regions, can be important drivers of peatland carbon accumulation and by extension, global climate, warranting further consideration in predictions of future climate variability.

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  • 39. Lapierre, Jean-Francois
    et al.
    Seekell, David A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Filstrup, Christopher T.
    Collins, Sarah M.
    Fergus, C. Emi
    Soranno, Patricia A.
    Cheruvelil, Kendra S.
    Continental-scale variation in controls of summer CO2 in United States lakes2017In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, no 4, p. 875-885Article in journal (Refereed)
    Abstract [en]

    Understanding the broad-scale response of lake CO2 dynamics to global change is challenging because the relative importance of different controls of surface water CO2 is not known across broad geographic extents. Using geostatistical analyses of 1080 lakes in the conterminous United States, we found that lake partial pressure of CO2 (pCO(2)) was controlled by different chemical and biological factors related to inputs and losses of CO2 along climate, topography, geomorphology, and land use gradients. Despite weak spatial patterns in pCO(2) across the study extent, there were strong regional patterns in the pCO(2) driver-response relationships, i.e., in pCO(2) regulation. Because relationships between lake CO2 and its predictors varied spatially, global models performed poorly in explaining the variability in CO2 for U.S. lakes. The geographically varying driver-response relationships of lake pCO(2) reflected major landscape gradients across the study extent and pointed to the importance of regional-scale variation in pCO(2) regulation. These results indicate a higher level of organization for these physically disconnected systems than previously thought and suggest that changes in climate and land use could induce shifts in the main pathways that determine the role of lakes as sources and sinks of atmospheric CO2. Plain Language Summary In this study we show that changes in climate and terrestrial landscapes could affect which are the main mechanisms responsible for the widespread emissions of CO2 by lakes. Although mechanisms such as aquatic primary production, respiration by microorganisms, or terrestrial loadings of carbon have been studied extensively, their relative importance across broad geographic extents with different climate or land use remains unknown. Based on an analysis of 1080 lakes distributed across the continental U.S., we show that lake CO2 dynamics depend on the climate and landscape context where these lakes are found, such as precipitation, elevation, percent agriculture, or wetlands in the lakes catchments. We observed a widespread effect of in-lake primary production, while the color of water, which has often been identified as one of the main controls of lake CO2 in northern lakes, was important in only a small fraction of the lakes studied. Our results show that controls on lake CO2 dynamics vary geographically and that considering that variation will be important for creating accurate global carbon models.

  • 40.
    Lidberg, William
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Moshyttan: Sweden’s oldest known blast furnace?: A multiproxy study based on geochemical and pollen analyses2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Radiocarbon datings in a previous study suggested that Moshyttan in Nora bergslag is the oldest blast furnace in Sweden and Europe. The aim of this study was specifically to study the origin of the Moshyttan blast furnace to answer the question: when was the blast furnace at Moshyttan established? To this end, a 2.5 m sediment record was collected from Fickeln, a lake 600 m downstream of Moshyttan, in March 2012. The geochemical properties of the sediment record were analyzed for major and trace elements using XRF. The organic content was calculated from the ash residue following the mercury analyses as a proxy for organic matter. Pollen and charcoal were analyzed using a standardized method. A age- depth model was created based on four radiocarbon datings of the sediment profile. The pollen data suggest that early land use consisted of forest grazing from about AD 220, and agriculture from about AD 880. An increase in Pb and charcoal particles about AD 880 indicates early metallurgy in the area. The first significant evidence of the establishment of a blastfurnace was between AD 1020 and AD 1090 marked by a decrease in organic content combined with a strong increase of ore related metals such as Pb, Zn, Cu and a strong increase of charcoal particles. Within the uncertainty of the age-depth modeling, the results from this study offers support to Wetterholms radiocarbon datings, thus making Moshyttan the oldest known blast furnace in Sweden and Europe. 

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    Masterexamensarbete William Lidberg
  • 41.
    Lin, Qi
    et al.
    State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China.
    Liu, Enfeng
    College of Geography and Environment, Shandong Normal University, Ji'nan, China.
    Zhang, Enlou
    State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nath, Bibhash
    Department of Geography and Environmental Science, Hunter College of the City University of New York, NY, United States.
    Zhang, Ke
    State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China.
    Shen, Ji
    School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, China.
    Spatial variation of organic carbon sequestration in large lakes and implications for carbon stock quantification2022In: Catena (Cremlingen. Print), ISSN 0341-8162, E-ISSN 1872-6887, Vol. 208, article id 105768Article in journal (Refereed)
    Abstract [en]

    Lakes are recognized as critical zones for carbon transformation and storage, and lacustrine sediments sequestrate considerable amounts of organic carbon (OC). Understanding sedimentation processes and OC burial patterns is crucial to clarifying lakes’ role in global carbon cycling. However, OC sedimentation may be quite spatially heterogeneous within an aquatic system, owing to the differences in OC production and sources, hydrodynamic conditions and underwater topography. The uncertainties in estimating OC sequestration in the world’s large lakes remain poorly constrained. This study takes the test case of two large lakes (50 and 249 km2) with different water depth and trophic status, using a multi-core paleolimnological technique, to identify the spatial variation in OC accumulation and its main influencing factors over the past century. Results of multi-core comparisons revealed similar temporal trends in major organic and nutrient parameters, suggesting coherent processes of whole-lake sedimentary environment changes for each lake. The OC preserved in sediments was primarily of autochthonous origin. However, OC standing stocks varied ∼3-fold spatially, and average OC accumulation rates ranged between 9.5–27.4 g m−2 yr−1 (post–1963 in oligo-mesotrophic deep-lake Lugu) and between 17.4–43.5 g m−2 yr−1 (post–1980 in eutrophic shallow-lake Erhai), respectively. These variations were primarily attributable to the spatial differences in aquatic primary production and terrestrial detritus supply relating to anthropogenic land-use change and phosphorus loading, rather than intra-lake sediment focusing-related transport and redistribution. The single central-core approach from Lugu Lake would overestimate whole-lake OC stock by 32% or underestimate the value by 48%, indicating spatial variability is an important source of uncertainty for OC stock quantification in similar large and/or morphometrically complex waterbodies. Therefore, spatial heterogeneity of OC accumulation in inland waters requires considerable research with well-placed multi-cores to provide a deeper understanding of carbon sequestration patterns and mechanisms.

  • 42. Lindstedt, T
    et al.
    Khotyaintsev, YV
    Vaivads, A
    André, M
    Nilsson, H
    Waara, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Oxygen energization by localized perpendicular electric fields at the cusp boundary2010In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, no 9, article id L09103Article in journal (Refereed)
    Abstract [en]

    We report Cluster observations of oxygen energization by several keV at the boundary between the high latitude cusp and lobe. A localized electric field at the cusp/lobe boundary is responsible for a significant part of the observed energization. Such electric fields can be related to the separatrix region of reconnection at the magnetopause. Ions are accelerated as they move non-adiabatically in the spatially inhomogeneous electric field. Additional heating may be provided by low frequency waves at the oxygen gyrofrequency. Citation: Lindstedt, T., Y. V. Khotyaintsev, A. Vaivads, M. Andre, H. Nilsson, and M. Waara (2010), Oxygen energization by localized perpendicular electric fields at the cusp boundary.

  • 43.
    Lundin, Erik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Klaminder, Jonatan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bastviken, David
    Department of Thematic Studies–Water and Environmental Studies, Linköping University, Linköping, Sweden.
    Olid, Carolina
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hansson, Sophia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Strong climate impact on the carbon emission – burial balance inhigh latitude lakesManuscript (preprint) (Other academic)
    Abstract [en]

    Lakes play an important role in the global carbon (C) cycle by burying C in sediments and emitting CO2 and CH4 to the atmosphere. The strengths of these fundamentally different pathways are critical for quantifying effects of lakes upon the climate system. In this study, based on new high-resolution estimates in combination with literature data, we show a generally ten times higher emission:burial ratio in boreal compared to subarctic-arctic lakes. These results suggest a major bioclimatic impact on C cycling in lakes, as lakes in warmer boreal regions emit more and store relatively less C than lakes in colder arctic regions. Thus, our results reveal a previously unforeseen longterm climate feedback: if predictions of the northward expansion of the boreal biome are correct, C emissions of high latitude lakes may increase four-fold, corresponding to 14% of present global lake C evasion to the atmosphere. Such effects are of major importance for understanding feedbacks of climate warming on the continental source-sink function at high latitudes

     

     

  • 44.
    Magnusson, Noel
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Assessing the viability of methylene blue titration for quantifying Bentonite in till soils: A case study from the Blaiken mine complex in Sorsele municipality, Sweden2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abandoned mines present considerable environmental risks through the release of toxic metals, particularly into adjacent water bodies. The implementation of reliable geotechnical cut-off walls containing bentonite stands as a crucial strategy in mitigating environmental groundwater contamination. This study evaluates the viability of employing the methylene blue titration method to quantify bentonite content in till samples, with the objective of verifying the assumed bentonite content (3.5%) and exploring the impact of sample preparation on bentonite content determined through titrations. Bentonite, known for its swelling properties and high cation exchange capacity, was introduced into till samples both in laboratory settings and on-site. The methylene blue titration method was utilized to measure bentonite content in these samples. Laboratory results indicated significant variations in bentonite content depending on the sample preparation method, with methods employing soil homogenization proving more effective in quantifying bentonite accurately. The study's findings support the hypothesis that the methylene blue method can reliably quantify bentonite in till soil samples with the correct preparation in a laboratory environment. On-site analysis exhibited larger variations and deviations in bentonite content quantifications compared to laboratory-based incorporations. Additionally, on-site incorporated samples demonstrated a statistically significant difference in bentonite content compared to laboratory-incorporated samples, highlighting the method's sensitivity and need for future research. This research contributes valuable insights into leveraging methylene blue titration for quantifying bentonite in till soils, crucial for establishing geotechnical barriers to control toxic metal output from mines.

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  • 45. Martinez Cortizas, Antonio
    et al.
    Lopez-Costas, Olalla
    Orme, Lisa
    Mighall, Tim
    Kylander, Malin E.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Gallego Sala, Angela
    Holocene atmospheric dust deposition in NW Spain2020In: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 30, no 4, p. 507-518Article in journal (Refereed)
    Abstract [en]

    Atmospheric dust plays an important role in terrestrial and marine ecosystems, particularly those that are nutrient limited. Despite that most dust originates from arid and semi-arid regions, recent research has shown that past dust events may have been involved in boosting productivity in nutrient-poor peatlands. We investigated dust deposition in a mid-latitude, raised bog, which is surrounded by a complex geology (paragneiss/schist, granite, quartzite and granodiorite). As proxies for dust fluxes, we used accumulation rates of trace (Ti, Zr, Rb, Sr and Y) as well as major (K and Ca) lithogenic elements. The oldest, largest dust deposition event occurred between similar to 8.6 and similar to 7.4 ka BP, peaking at similar to 8.1 ka BP (most probably the 8.2 ka BP event). The event had a large impact on the evolution of the mire, which subsequently transitioned from a fen into a raised bog in similar to 1500 years. From similar to 6.7 to similar to 4.0 ka BP, fluxes were very low, coeval with mid-Holocene forest stability and maximum extent. In the late Holocene, after similar to 4.0 ka BP, dust events became more prevalent with relatively major deposition at similar to 3.2-2.5, similar to 1.4 ka BP and similar to 0.35-0.05 ka BP, and minor peaks at similar to 4.0-3.7, similar to 1.7, similar to 1.10-0.95 ka BP and similar to 0.74-0.58 ka BP. Strontium fluxes display a similar pattern between similar to 11 and similar to 6.7 ka BP but then became decoupled from the other elements from the mid Holocene onwards. This seems to be a specific signal of the granodiorite batholith, which has an Sr anomaly. The reconstructed variations in dust fluxes bear a strong climatic imprint, probably related to storminess controlled by North Atlantic Oscillation conditions. Complex interactions also arise because of increased pressure from human activities.

  • 46.
    Mason, Richard J.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Loughborough University, Loughborough, United Kingdom.
    Rice, S.P.
    Loughborough University, Loughborough, United Kingdom.
    Johnson, M.F.
    University of Nottingham, Nottingham, United Kingdom.
    Wood, P.J.
    Loughborough University, Loughborough, United Kingdom.
    Vettori, D.
    Politecnico di Torino, Torino, Italy.
    Aquatic Insect Bioconstructions Modify Fine-Sediment Entrainment and Mobility2022In: Journal of Geophysical Research - Earth Surface, ISSN 2169-9003, E-ISSN 2169-9011, Vol. 127, no 2, article id e2021JF006399Article in journal (Refereed)
    Abstract [en]

    The importance of two-way interactions between animals and the physical hydraulic and sedimentological environment are increasingly recognized (e.g., zoogeomorphology). Caddisflies (Trichoptera) are a group of aquatic insects known for their bioconstructions, particularly cases built from fine sediment and silk. Caddisfly cases differ in size, shape and density from the incorporated sediment, and case construction may therefore affect the mobility of these sediments in rivers. However, although communities of caddisfly often use substantial quantities of sediment in case construction, the effect of these bioconstructions on sediment transport in rivers is unknown. We use a flume experiment to compare the bed shear stress required to transport (a) empty caddisfly cases and (b) individual sediment particles, following disaggregation from the case. The cases of three species were considered; two that construct different styles of tubular case (Potamophlax latipennis and Sericostoma personatum) and one that builds a domed case (Agapetus fuscipes). P. latipennis and S. personatum cases were easier to entrain than the sediment grains incorporated into them, whilst A. fuscipes cases were not. Despite their low mass, A. fuscipes cases required the most shear stress to transport them because their domed shape impeded rolling. These findings are important to understand how differences in case design between species, reflect different adaptation strategies to the turbulent hydraulic river habitat. Furthermore, the results suggest that un-attached tubular caddisfly cases may be preferentially transported over other particles on the river bed and thus, where caddisfly occur in high abundance, they may increase fluvial entrainment of sand.

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  • 47. Morrison, Kathleen D.
    et al.
    Hammer, Emily
    Boles, Oliver
    Madella, Marco
    Whitehouse, Nicola
    Gaillard, Marie-Jose
    Bates, Jennifer
    Vander Linden, Marc
    Merlo, Stefania
    Yao, Alice
    Popova, Laura
    Hill, Austin Chad
    Antolin, Ferran
    Bauer, Andrew
    Biagetti, Stefano
    Bishop, Rosie R.
    Buckland, Philip I.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Cruz, Pablo
    Dreslerová, Dagmar
    Dusseldorp, Gerrit
    Ellis, Erle
    Filipovic, Dragana
    Foster, Thomas
    Hannaford, Matthew J.
    Harrison, Sandy P.
    Hazarika, Manjil
    Herold, Hajnalka
    Hilpert, Johanna
    Kaplan, Jed O.
    Kay, Andrea
    Klein Goldewijk, Kees
    Kolář, Jan
    Kyazike, Elizabeth
    Laabs, Julian
    Lancelotti, Carla
    Lane, Paul
    Lawrence, Dan
    Lewis, Krista
    Lombardo, Umberto
    Lucarini, Giulio
    Arroyo-Kalin, Manuel
    Marchant, Rob
    Mayle, Francis
    McClatchie, Meriel
    McLeester, Madeleine
    Mooney, Scott
    Moskal-del Hoyo, Magdalena
    Navarrete, Vanessa
    Ndiema, Emmanuel
    Góes Neves, Eduardo
    Nowak, Marek
    Out, Welmoed A.
    Petrie, Cameron
    Phelps, Leanne N.
    Pinke, Zsolt
    Rostain, Stéphen
    Russell, Thembi
    Sluyter, Andrew
    Styring, Amy K.
    Tamanaha, Eduardo
    Thomas, Evert
    Veerasamy, Selvakumar
    Welton, Lynn
    Zanon, Marco
    Mapping past human land use using archaeological data: A new classification for global land use synthesis and data harmonization2021In: PLOS ONE, E-ISSN 1932-6203, Vol. 16, no 4, article id e0246662Article in journal (Refereed)
    Abstract [en]

    In the 12,000 years preceding the Industrial Revolution, human activities led to significant changes in land cover, plant and animal distributions, surface hydrology, and biochemical cycles. Earth system models suggest that this anthropogenic land cover change influenced regional and global climate. However, the representation of past land use in earth system models is currently oversimplified. As a result, there are large uncertainties in the current understanding of the past and current state of the earth system. In order to improve representation of the variety and scale of impacts that past land use had on the earth system, a global effort is underway to aggregate and synthesize archaeological and historical evidence of land use systems. Here we present a simple, hierarchical classification of land use systems designed to be used with archaeological and historical data at a global scale and a schema of codes that identify land use practices common to a range of systems, both implemented in a geospatial database. The classification scheme and database resulted from an extensive process of consultation with researchers worldwide. Our scheme is designed to deliver consistent, empirically robust data for the improvement of land use models, while simultaneously allowing for a comparative, detailed mapping of land use relevant to the needs of historical scholars. To illustrate the benefits of the classification scheme and methods for mapping historical land use, we apply it to Mesopotamia and Arabia at 6 kya (c. 4000 BCE). The scheme will be used to describe land use by the Past Global Changes (PAGES) LandCover6k working group, an international project comprised of archaeologists, historians, geographers, paleoecologists, and modelers. Beyond this, the scheme has a wide utility for creating a common language between research and policy communities, linking archaeologists with climate modelers, biodiversity conservation workers and initiatives.

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  • 48. Nakamura, R.
    et al.
    Karlsson, T.
    Hamrin, Maria
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nilsson, H.
    Swedish Inst Space Phys, S-98128 Kiruna, Sweden.
    Marghitu, O.
    Amm, O.
    Bunescu, C.
    Constantinescu, V.
    Frey, H. U.
    Keiling, A.
    Semeter, J.
    Sorbalo, E.
    Vogt, J.
    Forsyth, C.
    Kubyshkina, M. V.
    Low- altitude electron acceleration due to multiple flow bursts in the magnetotail2014In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 41, no 3, p. 777-784Article in journal (Refereed)
    Abstract [en]

    At 10:00 UT on 25 February 2008, Cluster 1 spacecraft crossed the near-midnight auroral zone, at about 2R(E) altitude, while two of the Time History of Events and Macroscale Interactions During Substorms (THEMIS) spacecraft, THD and THE, observed multiple flow bursts on the near-conjugate plasma sheet field lines. The flow shear pattern at THEMIS was consistent with the vortical motion at duskside of a localized flow channel. Coinciding in time with the flow bursts, Cluster 1 observed bursts of counterstreaming electrons with mostly low energies (441eV), accompanied by short time scale (<5s) magnetic field disturbances embedded in flow-associated field-aligned current systems. This conjugate event not only confirms the idea that the plasma sheet flows are the driver of the kinetic Alfven waves accelerating the low-energy electrons but is a unique observation of disturbances in the high-altitude auroral region relevant to the multiple plasma sheet flows. Key Points <list list-type="bulleted"> <list-item id="grl51326-li-0001">First observation of multiple flow signatures on near-conjugate flux tubes <list-item id="grl51326-li-0002">Low-energy electron profile suggests Alfvenic acceleration due to fast flow <list-item id="grl51326-li-0003">Multiple flow bursts are obtained to extend over large radial distance in tail

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  • 49.
    Ninnes, Sofia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Tolu, Julie
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Meyer-Jacob, Carsten
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Mighall, Tim M.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Investigating molecular changes in organic matter composition in two Holocene lake-sediment records from central Sweden using pyrolysis-GC/MS2017In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, no 6, p. 1423-1438Article in journal (Refereed)
    Abstract [en]

    Organic matter (OM) is a key component of lake sediments, affecting carbon, nutrient, and trace metal cycling at local and global scales. Yet little is known about long-term (millennial) changes in OM composition due to the inherent chemical complexity arising from multiple OM sources and from secondary transformations. In this study we explore how the molecular composition of OM changes throughout the Holocene in two adjacent boreal lakes in central Sweden and compare molecular-level information with conventional OM variables, including total carbon, total nitrogen, C:N ratios, delta C-13, and delta N-15. To characterize the molecular OM composition, we employed a new method based on pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), which yields semiquantitative data on > 100 organic compounds of different origin and degradation status. We identify large changes in OM composition after deglaciation (circa 8500 +/- 500 B.C.), associated with early landscape development, and during the most recent 4050 years, driven by degradation processes. With molecular(-)level information we can also distinguish between natural landscape development and human catchment disturbance during the last 1700 years. Our study demonstrates that characterization of the molecular OM composition by the high-throughput PyGC/MS method is an efficient complement to conventional OM variables for identification and understanding of past OM dynamics in lake-sediment records. Holocene changes observed for pyrolytic compounds and compound classes known for having different reactivity indicate the need for further paleo-reconstruction of the molecular OM composition to better understand both past and future OM dynamics and associated environmental changes.

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  • 50.
    Nota, Kevin
    et al.
    Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.
    Klaminder, Jonatan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Milesi, Pascal
    Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden; Scilifelab, Uppsala, Sweden.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nobile, Alessandro
    Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.
    van Steijn, Tamara
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.
    Bertilsson, Stefan
    Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden; Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Svensson, Brita
    Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.
    Hirota, Shun K.
    Field Science Center, Graduate School of Agricultural Science, Tohoku University, 232-3 Yomogida, Miyagi, Japan.
    Matsuo, Ayumi
    Field Science Center, Graduate School of Agricultural Science, Tohoku University, 232-3 Yomogida, Miyagi, Japan.
    Gunnarsson, Urban
    Swedish Environmental Protection Agency, SE-106 48, Stockholm, Sweden.
    Seppä, Heikki
    Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland.
    Väliranta, Minna M.
    Environmental Change Research Unit (ECRU), Ecosystems, Environment Research Programme, University of Helsinki, Helsinki, Finland.
    Wohlfarth, Barbara
    Department of Geological Sciences, Stockholm University, and Bolin Centre for Climate Research, SE-10691, Stockholm, Sweden.
    Suyama, Yoshihisa
    Field Science Center, Graduate School of Agricultural Science, Tohoku University, 232-3 Yomogida, Miyagi, Japan.
    Parducci, Laura
    Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden; Department of Environmental Biology, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome, Italy.
    Norway spruce postglacial recolonization of Fennoscandia2022In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 1333Article in journal (Refereed)
    Abstract [en]

    Contrasting theories exist regarding how Norway spruce (Picea abies) recolonized Fennoscandia after the last glaciation and both early Holocene establishments from western microrefugia and late Holocene colonization from the east have been postulated. Here, we show that Norway spruce was present in southern Fennoscandia as early as 14.7 ± 0.1 cal. kyr BP and that the millennia-old clonal spruce trees present today in central Sweden likely arrived with an early Holocene migration from the east. Our findings are based on ancient sedimentary DNA from multiple European sites (N = 15) combined with nuclear and mitochondrial DNA analysis of ancient clonal (N = 135) and contemporary spruce forest trees (N = 129) from central Sweden. Our other findings imply that Norway spruce was present shortly after deglaciation at the margins of the Scandinavian Ice Sheet, and support previously disputed finds of pollen in southern Sweden claiming spruce establishment during the Lateglacial.

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