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  • 1.
    Aage, Hans
    Roskilde University, Denmark.
    25. Economic Instruments: Three Interlinkages Between Ecology and Economics2012In: Rural Development and Land Use / [ed] Lars Rydén and Ingrid Karlsson, Uppsala: Baltic University Press , 2012, 1, p. 280-293Chapter in book (Other (popular science, discussion, etc.))
  • 2.
    Aage, Hans
    Roskilde University, Denmark.
    51. The environment2002In: The Baltic Sea Region: Cultures, Politics, Societies / [ed] Witold Maciejewski, Uppsala: Baltic University Press , 2002, 1, p. 639-650Chapter in book (Other (popular science, discussion, etc.))
  • 3. Aaro, Sven
    et al.
    Sjöström, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Airborne and ground geophysics used for regional tectonic analysis2003In: IUGG 2003, Sapporo, Japan: No GAV.06/10P/A11-004, B260., 2003Conference paper (Refereed)
  • 4.
    Abbott, Benjamin
    et al.
    Univ Rennes 1, OSUR, CNRS, ECOBIO,UMR 6553, Rennes, France.
    Baranov, Viktor
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Berlin, Germany.
    Mendoza-Lera, Clara
    Ctr LyonVilleurbanne, UR MALY, Irstea, F-69616 Villeurbanne, France.
    Nikolakopoulou, Myrto
    Naturalea, Barcelona, Spain.
    Harjung, Astrid
    Univ Barcelona, E-08007 Barcelona, Spain.
    Kolbe, Tamara
    Univ Rennes 1, CNRS, OSURGeosci Rennes, UMR 6118, F-35014 Rennes, France.
    Balasubramanian, Mukundh
    BioSistemika Ltd, Ljubljana, Slovenia.
    Vaessen, Timothy N
    CEAB CSIC, Girona, Spain.
    Ciocca, Francesco
    Silixa, Elstree, England.
    Campeau, Audrey
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Wallin, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Romeijn, Paul
    Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England.
    Antonelli, Marta
    LIST, Esch Sur Alzette, Luxembourg.
    Goncalves, José
    Natl Inst Biol, Ljubljana, Slovenia.
    Datry, Thibault
    Ctr LyonVilleurbanne, UR MALY, Irstea, F-69616 Villeurbanne, France.
    Laverman, Anniet
    Univ Rennes 1, OSUR, CNRS, ECOBIO,UMR 6553, Rennes, France.
    de Dreuzý, Jean-Raynald
    Univ Rennes 1, CNRS, OSURGeosci Rennes, UMR 6118, F-35014 Rennes, France.
    David, Hannah M.
    Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England.
    Krause, Stefan
    Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England.
    Oldham, Carolyn
    Univ Western Australia, Civil Environm & Min Engn, Perth, WA, Australia.
    Pinay, Gilles
    Univ Rennes 1, OSUR, CNRS, ECOBIO,UMR 6553, Rennes, France.
    Using multi-tracer inference to move beyond single-catchment ecohydrology2016In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 160, p. 19-42Article in journal (Refereed)
    Abstract [en]

    Protecting or restoring aquatic ecosystems in the face of growing anthropogenic pressures requires an understanding of hydrological and biogeochemical functioning across multiple spatial and temporal scales. Recent technological and methodological advances have vastly increased the number and diversity of hydrological, biogeochemical, and ecological tracers available, providing potentially powerful tools to improve understanding of fundamental problems in ecohydrology, notably: 1. Identifying spatially explicit flowpaths, 2. Quantifying water residence time, and 3. Quantifying and localizing biogeochemical transformation. In this review, we synthesize the history of hydrological and biogeochemical theory, summarize modem tracer methods, and discuss how improved understanding of flowpath, residence time, and biogeochemical transformation can help ecohydrology move beyond description of site-specific heterogeneity. We focus on using multiple tracers with contrasting characteristics (crossing proxies) to infer ecosystem functioning across multiple scales. Specifically, we present how crossed proxies could test recent ecohydrological theory, combining the concepts of hotspots and hot moments with the Damkohler number in what we call the HotDam framework.

  • 5.
    Abbott, Benjamin W.
    et al.
    Univ Rennes 1, OSUR, CNRS, UMR ECOBIO 6553, F-35014 Rennes, France.;Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK USA.;Univ Alaska Fairbanks, Dept Biology& Wildlife, Fairbanks, AK USA..
    Jones, Jeremy B.
    Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK USA.;Univ Alaska Fairbanks, Dept Biology& Wildlife, Fairbanks, AK USA..
    Schuur, Edward A. G.
    No Arizona Univ, Ctr Ecosyst Sci & Soc, Flagstaff, AZ 86011 USA..
    Chapin, F. Stuart, III
    Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK USA.;Univ Alaska Fairbanks, Dept Biology& Wildlife, Fairbanks, AK USA..
    Bowden, William B.
    Univ Vermont, Rubenstein Sch Environm & Nat Resources, Burlington, VT 05405 USA..
    Bret-Harte, M. Syndonia
    Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK USA.;Univ Alaska Fairbanks, Dept Biology& Wildlife, Fairbanks, AK USA..
    Epstein, Howard E.
    Univ Virginia, Dept Environm Sci, Charlottesville, VA 22903 USA..
    Flannigan, Michael D.
    Univ Alberta, Dept Renewable Resources, Edmonton, AB T6G 2M7, Canada..
    Harms, Tamara K.
    Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK USA.;Univ Alaska Fairbanks, Dept Biology& Wildlife, Fairbanks, AK USA..
    Hollingsworth, Teresa N.
    Univ Alaska Fairbanks, PNW Res Stn, USDA Forest Serv, Fairbanks, AK USA..
    Mack, Michelle C.
    No Arizona Univ, Ctr Ecosyst Sci & Soc, Flagstaff, AZ 86011 USA..
    McGuire, A. David
    Univ Alaska Fairbanks, Alaska Cooperat Fish & Wildlife Res Unit, US Geol Survey, Anchorage, AK USA..
    Natali, Susan M.
    Woods Hole Res Ctr, Woods Hole, MA USA..
    Rocha, Adrian V.
    Univ Notre Dame, Dept Biol Sci, Notre Dame, IN 46556 USA.;Univ Notre Dame, Environm Change Initiat, Notre Dame, IN 46556 USA..
    Tank, Suzanne E.
    Univ Alberta, Dept Biol Sci, Edmonton, AB T6G 2M7, Canada..
    Turetsky, Merritt R.
    Univ Guelph, Dept Integrat Biol, Guelph, ON N1G 2W1, Canada..
    Vonk, Jorien E.
    Vrije Univ Amsterdam, Dept Earth Sci, Amsterdam, Netherlands..
    Wickland, Kimberly P.
    US Geol Survey, Natl Res Program, Boulder, CO USA..
    Aiken, George R.
    US Geol Survey, Natl Res Program, Boulder, CO USA..
    Alexander, Heather D.
    Mississippi State Univ, Forest & Wildlife Res Ctr, Mississippi State, MS 39762 USA..
    Amon, Rainer M. W.
    Texas A&M Univ, Galveston, TX USA..
    Benscoter, Brian W.
    Florida Atlantic Univ, Boca Raton, FL 33431 USA..
    Bergeron, Yves
    Univ Quebec Abitibi Temiscamingue, Forest Res Inst, Rouyn Noranda, PQ, Canada..
    Bishop, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. wedish Univ Agr Sci, Dept Aquat Sci & Assessment, S-90183 Umea, Sweden..
    Blarquez, Olivier
    Univ Montreal, Dept Geog, Montreal, PQ H3C 3J7, Canada..
    Bond-Lamberty, Ben
    Pacific NW Natl Lab, Richland, WA 99352 USA..
    Breen, Amy L.
    Univ Alaska Fairbanks, Int Arctic Res Ctr, Scenarios Network Alaska & Arctic Planning, Fairbanks, AK USA..
    Buffam, Ishi
    Univ Cincinnati, Cincinnati, OH 45221 USA..
    Cai, Yihua
    Xiamen Univ, State Key Lab Marine Environm Sci, Xiamen, Peoples R China..
    Carcaillet, Christopher
    Ecole Prat Hautes Etud, UMR5023, CNRS Lyon 1, Lyon, France..
    Carey, Sean K.
    McMaster Univ, Hamilton, ON L8S 4L8, Canada..
    Chen, Jing M.
    Univ Toronto, Toronto, ON M5S 1A1, Canada..
    Chen, Han Y. H.
    Lakehead Univ, Fac Nat Resources Management, Thunder Bay, ON P7B 5E1, Canada..
    Christensen, Torben R.
    Lund Univ, Arctic Res Ctr, S-22100 Lund, Sweden.;Aarhus Univ, DK-8000 Aarhus C, Denmark..
    Cooper, Lee W.
    Univ Maryland, Ctr Environm Sci, Bethesda, MD USA..
    Cornelissen, J. Hans C.
    Vrije Univ Amsterdam, Syst Ecol, Amsterdam, Netherlands..
    de Groot, William J.
    Nat Resources Canada, Canadian Forest Serv, Toronto, ON, Canada..
    DeLuca, Thomas H.
    Univ Washington, Sch Environm & Forest Sci, Seattle, WA 98195 USA..
    Dorrepaal, Ellen
    Umea Univ, Dept Ecol & Environm Sci, Climate Impacts Res Ctr, S-90187 Umea, Sweden..
    Fetcher, Ned
    Wilkes Univ, Inst Environm Sci & Sustainabil, Wilkes Barre, PA 18766 USA..
    Finlay, Jacques C.
    Univ Minnesota, Dept Ecol Evolut & Behav, Minneapolis, MN 55455 USA..
    Forbes, Bruce C.
    Univ Lapland, Arctic Ctr, Rovaniemi, Finland..
    French, Nancy H. F.
    Michigan Technol Univ, Michigan Tech Res Inst, Houghton, MI 49931 USA..
    Gauthier, Sylvie
    Nat Resources Canada, Canadian Forest Serv, Laurentian Forestry Ctr, Toronto, ON, Canada..
    Girardin, Martin P.
    Nat Resources Canada, Canadian Forest Serv, Laurentian Forestry Ctr, Toronto, ON, Canada..
    Goetz, Scott J.
    Woods Hole Res Ctr, Woods Hole, MA USA..
    Goldammer, Johann G.
    Max Planck Inst Chem, Global Fire Monitoring Ctr, Berlin, Germany..
    Gough, Laura
    Towson Univ, Dept Biol Sci, Towson, MD USA..
    Grogan, Paul
    Queens Univ, Dept Biol, Kingston, ON K7L 3N6, Canada..
    Guo, Laodong
    Univ Wisconsin Milwaukee, Sch Freshwater Sci, Milwaukee, WI USA..
    Higuera, Philip E.
    Univ Montana, Dept Ecosyst & Conservat Sci, Missoula, MT 59812 USA..
    Hinzman, Larry
    Univ Alaska Fairbanks, Fairbanks, AK USA..
    Hu, Feng Sheng
    Univ Illinois, Dept Plant Biol, Chicago, IL 60680 USA.;Univ Illinois, Dept Geol, Chicago, IL 60680 USA..
    Hugelius, Gustaf
    Stockholm Univ, Dept Phys Geog, Stockholm, Sweden..
    Jafarov, Elchin E.
    Univ Colorado Boulder, Inst Arctic & Alpine Res, Boulder, CO USA..
    Jandt, Randi
    Univ Alaska Fairbanks, Alaska Fire Sci Consortium, Fairbanks, AK USA..
    Johnstone, Jill F.
    Univ Saskatchewan, Dept Biol, Saskatoon, SK S7N 0W0, Canada..
    Karlsson, Jan
    Umea Univ, Dept Ecol & Environm Sci, Climate Impacts Res Ctr, S-90187 Umea, Sweden..
    Kasischke, Eric S.
    Univ Maryland, Dept Geog Sci, Bethesda, MD USA..
    Kattner, Gerhard
    Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Berlin, Germany..
    Kelly, Ryan
    Neptune & Co Inc, North Wales, PA USA..
    Keuper, Frida
    Umea Univ, Dept Ecol & Environm Sci, Climate Impacts Res Ctr, S-90187 Umea, Sweden.;INRA, AgroImpact UPR1158, New York, NY USA..
    Kling, George W.
    Univ Michigan, Ann Arbor, MI 48109 USA..
    Kortelainen, Pirkko
    Finnish Environm Inst, Helsinki, Finland..
    Kouki, Jari
    Univ Eastern Finland, Sch Forest Sci, Joensuu, Finland..
    Kuhry, Peter
    Stockholm Univ, Dept Phys Geog, Stockholm, Sweden..
    Laudon, Hjalmar
    Swedish Univ Agr Sci, Dept Forest Ecol & Management, S-90183 Umea, Sweden..
    Laurion, Isabelle
    Inst Natl Rech Sci, Ctr Eau Terre Environm, Toronto, ON, Canada..
    Macdonald, Robie W.
    Inst Ocean Sci, Dept Fisheries & Oceans, Toronto, ON, Canada..
    Mann, Paul J.
    Northumbria Univ, Dept Geog, Newcastle Upon Tyne NE1 8ST, Tyne & Wear, England..
    Martikainen, Pertti J.
    Univ Eastern Finland, Dept Environm & Biol Sci, Joensuu, Finland..
    McClelland, James W.
    Univ Texas Austin, Inst Marine Sci, Austin, TX 78712 USA..
    Molau, Ulf
    Univ Gothenburg, Dept Biol & Environm Sci, Gothenburg, Sweden..
    Oberbauer, Steven F.
    Florida Int Univ, Dept Biol Sci, Miami, FL 33199 USA..
    Olefeldt, David
    Univ Alberta, Dept Revewable Resources, Edmonton, AB T6G 2M7, Canada..
    Pare, David
    Nat Resources Canada, Canadian Forest Serv, Laurentian Forestry Ctr, Toronto, ON, Canada..
    Parisien, Marc-Andre
    Nat Resources Canada, Canadian Forest Serv, No Forestry Ctr, Toronto, ON, Canada..
    Payette, Serge
    Univ Laval, Ctr Etud Nord, Quebec City, PQ G1K 7P4, Canada..
    Peng, Changhui
    Univ Quebec, Ctr CEF, ESCER, Montreal, PQ H3C 3P8, Canada.;Northwest A&F Univ, Coll Forestry, State Key Lab Soil Eros & Dryland Farming Loess P, Xian, Peoples R China..
    Pokrovsky, Oleg S.
    CNRS, Georesources & Environm, Toulouse, France.;Tomsk State Univ, BIO GEO CLIM Lab, Tomsk, Russia..
    Rastetter, Edward B.
    Marine Biol Lab, Ctr Ecosyst, Woods Hole, MA 02543 USA..
    Raymond, Peter A.
    Yale Univ, Sch Forestry & Environm Studies, New Haven, CT 06520 USA..
    Raynolds, Martha K.
    Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK USA..
    Rein, Guillermo
    Univ London Imperial Coll Sci Technol & Med, Dept Mech Engn, London SW7 2AZ, England..
    Reynolds, James F.
    Lanzhou Univ, Sch Life Sci, Lanzhou 730000, Peoples R China.;Duke Univ, Nicholas Sch Environm, Durham, NC 27706 USA..
    Robards, Martin
    Arctic Beringia Program, Wildlife Conservat Soc, New York, NY USA..
    Rogers, Brendan M.
    Woods Hole Res Ctr, Woods Hole, MA USA..
    Schaedel, Christina
    No Arizona Univ, Ctr Ecosyst Sci & Soc, Flagstaff, AZ 86011 USA..
    Schaefer, Kevin
    Univ Colorado Boulder, Cooperat Inst Res Environm Sci, Natl Snow & Ice Data Ctr, Boulder, CO USA..
    Schmidt, Inger K.
    Univ Copenhagen, Dept Geosci & Nat Resource Management, DK-1168 Copenhagen, Denmark..
    Shvidenko, Anatoly
    Int Inst Appl Syst Anal, A-2361 Laxenburg, Austria.;Sukachev Inst Forest, Moscow, Russia..
    Sky, Jasper
    Cambridge Ctr Climate Change Res, Cambridge, England..
    Spencer, Robert G. M.
    Florida State Univ, Dept Earth Ocean & Atmospher Sci, Tallahassee, FL 32306 USA..
    Starr, Gregory
    Univ Alabama, Dept Biol Sci, Tuscaloosa, AL 35487 USA..
    Striegl, Robert G.
    US Geol Survey, Natl Res Program, Boulder, CO USA..
    Teisserenc, Roman
    Univ Toulouse, CNRS, INPT, ECOLAB,UPS, Toulouse, France..
    Tranvik, Lars J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Virtanen, Tarmo
    Univ Helsinki, Dept Environm Sci, FIN-00014 Helsinki, Finland..
    Welker, Jeffrey M.
    Univ Alaska Anchorage, Anchorage, AK USA..
    Zimov, Sergei
    Russian Acad Sci, Northeast Sci Stn, Moscow 117901, Russia..
    Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment2016In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 11, no 3, article id 034014Article in journal (Refereed)
    Abstract [en]

    As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.

  • 6. Abbuehl, Luca M.
    et al.
    Norton, Kevin P.
    Schlunegger, Fritz
    Kracht, Oliver
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    El Niño forcing on 10Be-based surface denudation rates in the northwestern Peruvian Andes?2010In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 123, no 3-4, p. 257-268Article in journal (Refereed)
    Abstract [en]

    High magnitude precipitation events provide large contributions to landscape formation and surface denudation in arid environments. Here, we quantify the precipitation-dependent geomorphic processes within the Rio Piura drainage basin located on the Western Escarpment of the northern Peruvian Andes at 5 degrees S latitude. In this region, monsoonal easterly winds bring precipitation to the >3000 m asl high headwaters, from where the annual amount of precipitation decreases downstream toward the Pacific coast. Denudation rates are highest in the knickzones near the headwaters, similar to 200-300 mm ky(-1), and sediment discharge is limited by the transport capacity of the channel network. Every few years, this situation is perturbed by westerly, wind-driven heavy precipitation during El Nino events and results in supply-limited sediment discharge as indicated by bedrock channels. The detailed analysis of the stream-long profiles of two river basins within the Rio Piura catchment reveals a distinct knickzone in the transition zone between the easterly and westerly climatic influences, suggesting an En Nino forcing on the longitudinal channel profiles over at least Holocene timescales. Measured trunk stream catchment-wide denudation rates are up to ca. 300 mm ky(-1) and decrease successively downstream along the river profiles. Denudation rates of tributary rivers are ca. 200 mm ky(-1) near the plateau and show a stronger downstream decreasing trend than trunk stream rates. This suggests that the landscape is in a transient stage of local relief growth, which is driven by fluvial incision. This corroborates the results of paleoclimate studies that point towards higher El Nino frequencies during the past ca. 3000 years, leading to higher runoff and more erosion in the trunk channel compared to the hillslopes and thus growth of local relief. Downstream increases in channel gradient spatially coincide with the reaches of highest precipitation rates during El Nino events, we therefore interpret that Holocene landscape evolution has largely been controlled by climate. The ky-timescale of the Be-10 data together with the transience of the landscape implies that El Nino events in northwestern Peru have occurred since at least the Holocene, and that adjustment to channel incision is still taking place.

  • 7.
    Abdi, Amir
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Heinonen, Suvi
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Karinen, Tuomo
    Constraints on the geometry of the Suasselka post-glacial fault, northern Finland, based on reflection seismic imaging2015In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 649, p. 130-138Article in journal (Refereed)
    Abstract [en]

    Unloading of the ice during the last glacial period in northern Fennoscandia is believed to have generated major faulting. These faults, often referred to as post-glacial faults, typically have clear surface exposures, but their geometry at depth is poorly known. In order to better understand the geometry at depth of the Suasselka post-glacial fault in Finland, three high resolution 2D reflection seismic profiles over the fault were reprocessed. Their total profile length is about 60 km and they were acquired as part of a major effort in Finland to map the uppermost crust in mining areas. The reprocessing led to significantly improved images that could be used to map the fault at depth. Two approximately N-S striking profiles and one E-W striking profile were reprocessed. The different azimuths and the crooked nature of the profiles allowed the fault geometry to be relatively well constrained. Clear reflections from the fault, dipping towards the SE, can be traced from the shallow subsurface down to about 3 km. The strike and dip of two sets of dipping reflections in the stacked data along with geometrical constraints and cross-dip analysis give a consistent dip of about 35-45 degrees towards the SE for the fault. The strike and dip vary from N55E with a dip of 35 degrees in the east to a strike of N48E with a dip of 45 degrees in the west. Existence of the two sets of reflections indicates that the fault surface is non-planar. Aside from allowing the geometry of the fault to be determined, the seismic data show a complex reflectivity pattern in the area and indications of both reverse and normal movement along fault planes with similar orientation to the Suasselka post-glacial fault. These images can be used as a basis for better characterizing the 3D geology of the area.

  • 8.
    Abdu, Y. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Annersten, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Ericsson, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Hawthorne, F. C.
    High-temperature cation ordering in olivine: an in situ Mossbauer study of synthetic (Mg0.55Fe0.45)(2) SiO42008In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 186, no 1-3, p. 99-103Article in journal (Refereed)
    Abstract [en]

    High- temperature in situ Mossbauer spectroscopy measurements ( 300 950. C) were done on synthetic olivine of composition ( Mg0.55Fe0.45) 2 SiO4 (= Fa45) in order to study the distribution of Fe2+ over the M1 and M2 octahedral sites. The spectra are fit with two doublets, which are assigned to Fe2+ at the M1 ( smaller splitting) and M2 sites. The Fe2+ site- occupancies at M1 and M2, obtained from the Mossbauer relative areas, suggest that Fe2+ has a slight preference for the M1 site at temperatures below similar to 500. C, with a tendency of disordering around this temperature. At higher temperatures, Fe2+ again prefers to occupy the M1 site, where it shows a considerable order at this site up to 750C. At still higher temperatures, the spectra indicated partial reduction of the Fa- component into metallic iron and the resolution of the doublets was severely deteriorated.

  • 9.
    Abdu, Yassir Ahmed Mohamed
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences.
    Mössbauer Spectroscopy of Meteoritic and Synthetic Fe-Ni Alloys2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis reports on the results of investigating Fe-containing minerals in meteorites, with focus on Fe-Ni minerals and their magnetic properties, along with some synthetic Fe-Ni analogues. The New Halfa meteorite, which fell in Sudan 1994, has been studied using Mössbauer spectroscopy, X-ray diffraction, and electron microprobe analysis techniques, and classified as an ordinary L-type chondrite of petrologic type 4. Mössbauer spectra of taenite-enriched samples from the metal particles of the New Halfa (L4) and Al Kidirate (H6) meteorites identify the following γ (fcc) Fe-Ni phases: the ferromagnetic atomically ordered taenite (tetrataenite) with ~ 50 at % Ni, the ferromagnetic disordered taenite with ~ 50 at % Ni, the low-Ni (~ 25 at %) paramagnetic taenite (antitaenite). The presence of the superstructure of tetrataenite is confirmed by synchrotron X-ray diffraction.

    Fe-rich γ (fcc) Fe-Ni alloys with compositions Fe79Ni21, Fe76Ni24, and Fe73Ni27, which serve as synthetic analogues of antitaenite, are prepared by mechanical alloying and subsequent annealing at 650 °C. The Mössbauer results indicate that these alloys are inhomogeneous and contain a high moment (HM) ferromagnetic Ni-rich phase (> 30 at % Ni) and a low moment (LM) paramagnetic Fe-rich phase, which orders antiferromagnetically at low temperature. The coexistence of these phases is attributed to phase segregation occurring on short range, probably nanometer scale, consistent with the Fe-Ni phase diagram below 400 °C where there is a miscibility gap associated with a spinodal decomposition in alloys with < 50 at % Ni.

    The combined high field Mössbauer spectroscopy and SQUID magnetometry results on these alloys at room temperature indicate large induced local magnetic moments in the paramagnetic part of the sample, which increases with increasing the Ni content. The results, when compared with the high field Mössbauer results on antitaenite from the metal particle of Al Kidirate and New Halfa meteorites may be used to estimate the Ni content of antitaenite in meteorites.

    High pressure 57Fe Mössbauer spectroscopy measurements up to ~ 41 GPa have been carried out at room temperature using the diamond anvil cell (DAC) technique in order to investigate the magnetic properties of γ (fcc) 57Fe53Ni47 alloy. The results indicate a pressure induced Invar effect at ~ 7 GPa and a non-magnetic or paramagnetic state above 20 GPa, demonstrating the volume dependence of the magnetic moment of γ (fcc) Fe-Ni alloys.

    List of papers
    1. Mössbauer spectroscopy, X-ray diffraction and electron microprobe analysis of the New Halfa meteorite
    Open this publication in new window or tab >>Mössbauer spectroscopy, X-ray diffraction and electron microprobe analysis of the New Halfa meteorite
    1997 In: Meteoritics and Planetary Science, Vol. 32, p. 373-375Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-91276 (URN)
    Available from: 2004-01-15 Created: 2004-01-15Bibliographically approved
    2. Mössbauer studies on the metallic phases of Al Kidirate and New Halfa Meteorites
    Open this publication in new window or tab >>Mössbauer studies on the metallic phases of Al Kidirate and New Halfa Meteorites
    Show others...
    2002 In: Hyperfine Interactions C, Vol. 5, p. 375-378Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-91277 (URN)
    Available from: 2004-01-15 Created: 2004-01-15Bibliographically approved
    3. Coexisting antiferromagnetism and ferromagnetism in mechanically alloyed Fe-rich Fe-Ni alloys: Implications regarding the Fe-Ni phase diagram below 400 °C
    Open this publication in new window or tab >>Coexisting antiferromagnetism and ferromagnetism in mechanically alloyed Fe-rich Fe-Ni alloys: Implications regarding the Fe-Ni phase diagram below 400 °C
    2004 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 280, no 2-3, p. 395-403Article in journal (Refereed) Published
    Abstract [en]

    Fe–Ni alloys below the Invar region with compositions Fe100−xNix (x=21, 24, and 27 at%) were prepared by high-energy ball milling technique (mechanical alloying). The as-milled samples, characterized by X-ray diffraction and Mössbauer spectroscopy, contain a mixture of α (BCC) and γ (FCC) phases, whereas the samples annealed at 650°C for 0.5 h show a single γ (FCC) phase displaying a single line Mössbauer spectrum at room temperature (RT). At low temperature, the Mössbauer spectra of annealed Fe76Ni24 and Fe73Ni27 alloys show the existence of a magnetically split pattern together with a broad singlet, which are ascribed to a high-moment ferromagnetic Ni-rich phase and a low-moment Fe-rich phase, respectively. The Fe-rich phase in annealed Fe76Ni24 alloy, which is paramagnetic at RT, undergoes antiferromagnetic ordering at ∼40 K, estimated from the dramatic line broadening of its spectrum, giving rise to a small hyperfine field (e.g. ∼2 T at 6 K). The coexistence of these phases is attributed to phase segregation occurring in these alloys as a result of enhanced atomic diffusion. The stability of these alloys towards martensitic (FCC→BCC) transformation at low temperatures is discussed in connection with the Fe–Ni phase diagram below 400°C.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-91278 (URN)10.1016/j.jmmm.2004.03.036 (DOI)
    Available from: 2004-01-15 Created: 2004-01-15 Last updated: 2017-12-14Bibliographically approved
    4. Field induced local magnetic moments in gamma-fcc Fe-Ni anti-Invar alloys
    Open this publication in new window or tab >>Field induced local magnetic moments in gamma-fcc Fe-Ni anti-Invar alloys
    2004 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 280, p. 243-250Article in journal (Refereed) Published
    Abstract [en]

    Mössbauer spectroscopy in longitudinal external fields (up to 7 T) and SQUID magnetometry (up to 5 T)measurements have been carried out on mechanically alloyed (MA) g (FCC) Fe100xNix (x ¼ 21; 24, and 27 at%) alloysat room temperature. The zero-field M.ossbauer spectra of these alloys show only singlets. The high field M.ossbauerresults indicate that large amounts of the material is in the paramagnetic state, giving rise to two spectral componentswith their effective fields almost linearly depend on the external field, but with slopes that are smaller than unity. The infieldM.ossbauer spectra of the x ¼ 27 at% alloy show an additional component with a hyperfine field of E21 T, whichis attributed to Ni-rich (>30 at% Ni) clusters (domains) of ferromagnetically ordered HM phase that behavessuperparamagnetically at room temperature and shows a non-linear character in the magnetization (M–H) curves atlow fields. This HM phase is also present in the x ¼ 21 and 24 at% samples but with smaller amounts. The resultssuggest induced hyperfine fields and hence induced moments in the paramagnetic components, which increases withincreasing Ni contents. Taenite-enriched samples from the metal particles of two stony meteorites, Al Kidirate (H6)and New Halfa (L4), are also studied by high field M.ossbauer spectroscopy and the results are compared to that ofMA samples.

    Keywords
    Mössbauer spectroscopy; External field; Magnetization; Fe–Ni alloys; Antitaenite
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-91279 (URN)
    Available from: 2004-01-15 Created: 2004-01-15 Last updated: 2017-12-14Bibliographically approved
    5. Non-magnetic stainless steels reinvestigated: A small effective field component in external magnetic fields
    Open this publication in new window or tab >>Non-magnetic stainless steels reinvestigated: A small effective field component in external magnetic fields
    2004 (English)In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 156/157, p. 151-155Article in journal (Refereed) Published
    Abstract [en]

    Three standard non-magnetic stainl ess steels of composition (wt%) Fe 70 Cr 19 Ni 11 , Fe 70 Cr 17 Ni 13 and Fe 69 Cr 18 . 5 Ni 10 . 3 Mn 1 . 8 Ti 0 . 4 have been investigated by Mössbauer spectroscopy (5–295 K and in external fields 7 T at room temperature) and ma gnetization measurements (10– 300 K) using a SQUID magnetometer. There are indications of a field induced ferromagnetic inter- action in the samples at room temperature

    Keywords
    stainless steel, external field, field induced ferromagnetism
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-91280 (URN)
    Available from: 2004-01-15 Created: 2004-01-15 Last updated: 2017-12-14Bibliographically approved
    6. High pressure Mössbauer studies on fcc Fe53Ni47 alloy
    Open this publication in new window or tab >>High pressure Mössbauer studies on fcc Fe53Ni47 alloy
    2004 (English)In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 156, p. 394-, article id 389Article in journal (Refereed) Published
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-91281 (URN)10.1007/978-1-4020-2852-6_59 (DOI)
    Available from: 2004-01-15 Created: 2004-01-15 Last updated: 2017-12-14Bibliographically approved
  • 10.
    Abeysinghe, Kasun S.
    et al.
    Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550081, Guizhou, Peoples R China.;Chinese Acad Sci, Key Lab Trop Forest Ecol, Xishuangbanna Trop Bot Garden, Mengla 666303, Yunnan, Peoples R China.;Guangxi Univ, Coll Forestry, Guangxi Key Lab Forest Ecol & Conservat, 100 Daxue Rd,Coll Forestry Off 519, Nanning 530005, Guangxi, Peoples R China.;Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China..
    Qiu, Guangle
    Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550081, Guizhou, Peoples R China..
    Goodale, Eben
    Guangxi Univ, Coll Forestry, Guangxi Key Lab Forest Ecol & Conservat, 100 Daxue Rd,Coll Forestry Off 519, Nanning 530005, Guangxi, Peoples R China..
    Anderson, Christopher W. N.
    Massey Univ, Inst Agr & Environm, Soil & Earth Sci, Palmerston North 4442, New Zealand..
    Bishop, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Lennart Hjelmsvag 9, SE-75007 Uppsala, Sweden..
    Evers, David C.
    Biodivers Res Inst, 276 Canco Rd, Portland, ME 04103 USA..
    Goodale, Morgan W.
    Biodivers Res Inst, 276 Canco Rd, Portland, ME 04103 USA..
    Hintelmann, Holger
    Trent Univ, Chem Dept, 1600 West Bank Dr, Peterborough, ON K9J 7B8, Canada..
    Liu, Shengjie
    Chinese Acad Sci, Key Lab Trop Forest Ecol, Xishuangbanna Trop Bot Garden, Mengla 666303, Yunnan, Peoples R China.;Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China..
    Mammides, Christos
    Chinese Acad Sci, Key Lab Trop Forest Ecol, Xishuangbanna Trop Bot Garden, Mengla 666303, Yunnan, Peoples R China..
    Quan, Rui-Chang
    Chinese Acad Sci, Key Lab Trop Forest Ecol, Xishuangbanna Trop Bot Garden, Mengla 666303, Yunnan, Peoples R China..
    Wang, Jin
    Chinese Acad Sci, Key Lab Trop Forest Ecol, Xishuangbanna Trop Bot Garden, Mengla 666303, Yunnan, Peoples R China.;Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China..
    Wu, Pianpian
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Lennart Hjelmsvag 9, SE-75007 Uppsala, Sweden..
    Xu, Xiao-Hang
    Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550081, Guizhou, Peoples R China.;Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China..
    Yang, Xiao-Doug
    Chinese Acad Sci, Key Lab Trop Forest Ecol, Xishuangbanna Trop Bot Garden, Mengla 666303, Yunnan, Peoples R China..
    Feng, Xinbin
    Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550081, Guizhou, Peoples R China..
    Mercury flow through an Asian rice-based food web2017In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 229, p. 219-228Article in journal (Refereed)
    Abstract [en]

    Mercury (Hg) is a globally-distributed pollutant, toxic to humans and animals. Emissions are particularly high in Asia, and the source of exposure for humans there may also be different from other regions, including rice as well as fish consumption, particularly in contaminated areas. Yet the threats Asian wildlife face in rice-based ecosystems are as yet unclear. We sought to understand how Hg flows through rice-based food webs in historic mining and non-mining regions of Guizhou, China. We measured total Hg (THg) and methylmercury (MeHg) in soil, rice, 38 animal species (27 for MeHg) spanning multiple trophic levels, and examined the relationship between stable isotopes and Hg concentrations. Our results confirm biomagnification of THg/MeHg, with a high trophic magnification slope. Invertivorous songbirds had concentrations of THg in their feathers that were 15x and 3x the concentration reported to significantly impair reproduction, at mining and non-mining sites, respectively. High concentrations in specialist rice consumers and in granivorous birds, the later as high as in piscivorous birds,, suggest rice is a primary source of exposure. Spiders had the highest THg concentrations among invertebrates and may represent a vector through which Hg is passed to vertebrates, especially songbirds. Our findings suggest there could be significant population level health effects and consequent biodiversity loss in sensitive ecosystems, like agricultural wetlands, across Asia, and invertivorous songbirds would be good subjects for further studies investigating this possibility.

  • 11.
    Abeysinghe, Kasun S.
    et al.
    Chinese Acad Sci, Xishuangbanna Trop Bot Garden, Key Lab Trop Forest Ecol, Mengla, Yunnan, Peoples R China.;Univ Chinese Acad Sci, Beijing, Peoples R China..
    Yang, Xiao-Dong
    Chinese Acad Sci, Xishuangbanna Trop Bot Garden, Key Lab Trop Forest Ecol, Mengla, Yunnan, Peoples R China..
    Goodale, Eben
    Guangxi Univ, Coll Forestry, Nanning, Guangxi, Peoples R China..
    Anderson, Christopher W. N.
    Massey Univ, Inst Agr & Environm, Soil & Earth Sci, Palmerston North, New Zealand..
    Bishop, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden..
    Cao, Axiang
    Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang, Peoples R China.;Guizhou Normal Univ, Sch Chem & Mat Sci, Guiyang, Peoples R China..
    Feng, Xinbin
    Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang, Peoples R China..
    Liu, Shengjie
    Chinese Acad Sci, Xishuangbanna Trop Bot Garden, Key Lab Trop Forest Ecol, Mengla, Yunnan, Peoples R China.;Univ Chinese Acad Sci, Beijing, Peoples R China..
    Mammides, Christos
    Chinese Acad Sci, Xishuangbanna Trop Bot Garden, Key Lab Trop Forest Ecol, Mengla, Yunnan, Peoples R China..
    Meng, Bo
    Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang, Peoples R China..
    Quan, Rui-Chang
    Chinese Acad Sci, Xishuangbanna Trop Bot Garden, Key Lab Trop Forest Ecol, Mengla, Yunnan, Peoples R China..
    Sun, Jing
    Nanjing Agr Univ, Coll Resources & Environm Sci, Nanjing, Jiangsu, Peoples R China..
    Qiu, Guangle
    Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang, Peoples R China..
    Total mercury and methylmercury concentrations over a gradient of contamination in earthworms living in rice paddy soil2017In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 36, no 5, p. 1202-1210Article in journal (Refereed)
    Abstract [en]

    Mercury (Hg) deposited from emissions or from local contamination, can have serious health effects on humans and wildlife. Traditionally, Hg has been seen as a threat to aquatic wildlife, because of its conversion in suboxic conditions into bioavailable methylmercury (MeHg), but it can also threaten contaminated terrestrial ecosystems. In Asia, rice paddies in particular may be sensitive ecosystems. Earthworms are soil-dwelling organisms that have been used as indicators of Hg bioavailability; however, the MeHg concentrations they accumulate in rice paddy environments are not well known. Earthworm and soil samples were collected from rice paddies at progressive distances from abandoned mercury mines in Guizhou, China, and at control sites without a history of Hg mining. Total Hg (THg) and MeHg concentrations declined in soil and earthworms as distance increased from the mines, but the percentage of THg that was MeHg, and the bioaccumulation factors in earthworms, increased over this gradient. This escalation in methylation and the incursion of MeHg into earthworms may be influenced by more acidic soil conditions and higher organic content further from the mines. In areas where the source of Hg is deposition, especially in water-logged and acidic rice paddy soil, earthworms may biomagnify MeHg more than was previously reported. It is emphasized that rice paddy environments affected by acidifying deposition may be widely dispersed throughout Asia.

  • 12.
    Abiodun, B. and Enger, L.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences.
    The role of advection of fluxes on modelling dispersion in convective boundary2002In: Quart. J. Roy. Met. Soc., Vol. 128, p. 1589-1607Article in journal (Refereed)
  • 13.
    Abirifard, Mahmoud
    et al.
    Shiraz Univ, Coll Sci, Dept Earth Sci, Shiraz, Iran..
    Raeisi, Ezzat
    Shiraz Univ, Coll Sci, Dept Earth Sci, Shiraz, Iran..
    Zarei, Mehdi
    Shiraz Univ, Coll Sci, Dept Earth Sci, Shiraz, Iran..
    Zare, Mohammad
    Shiraz Univ, Coll Sci, Dept Earth Sci, Shiraz, Iran..
    Filippi, Michal
    Czech Acad Sci, Inst Geol, Vvi, Rozvojova 269, Prague 6, Czech Republic..
    Bruthans, Jiri
    Charles Univ Prague, Fac Sci, Albertov 6, Prague 12843 2, Czech Republic..
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Jahani Salt Diapir, Iran: hydrogeology, karst features and effect on surroundings environment2017In: International Journal of Speleology, ISSN 0392-6672, E-ISSN 1827-806X, Vol. 46, no 3, p. 445-457Article in journal (Refereed)
    Abstract [en]

    The Jahani Salt Diapir (JSD), with an area of 54 km(2), is an active diapir in the Simply Folded Belt of the Zagros Orogeny, in the south of Iran. Most of the available studies on this diapir are focused on tectonics. The hydrogeology, schematic model of flow direction and hydrochemical effects of the JSD on the adjacent water resources are lacking, and thus, are the focus of this study. The morphology of the JSD was reevaluated by fieldwork and using available maps. The physicochemical characteristics of the springs and hydrometric stations were also measured. The vent of the diapir is located 250 m higher than the surrounding glaciers, and covered by small polygonal sinkholes (dolines). The glacier is covered by cap soils, sparse trees and pastures, and contains large sinkholes, numerous shafts, several caves, and 30 brine springs. Two main groups of caves were distinguished. Sub-horizontal or inclined stream passages following the surface valleys and vertical shafts (with short inlet caves) at the bottoms of nearly circular blind valleys. Salt exposure is limited to steep slopes. The controlling variables of flow route within salt diapirs are the negligible porosity of the salt rocks at depth more than about ten meters below the ground surface and the rapid halite saturation along the flow route. These mechanisms prevent deep cave development and enforce the emergence points of brine springs with low flow rates and small catchment area throughout the JSD and above the local base of erosion. Tectonics do not affect karst development, because the distributions of sinkholes and brine springs show no preferential directions. The type of spring water is sodium chloride, with a TDS of 320 g/l, and saturated with halite, gypsum, calcite and dolomite. The water balance budget of the JSD indicates that the total recharge water is 1.46 MCM (million cubic meter)/a, emerges from 30 brine springs, two springs from the adjacent karstic limestone, and flows into the Firoozabad River (FR) and the adjacent alluvium aquifer. The FR cuts through the northern margin of the salt diapir, dissolving the glacier salts at the contact with JSD, increasing the halite concentration of the 17.7 MCM/a of the FR from 100 mg/l to 12,000 mg/l. This is a permanent process because the active glacier flows rapidly down the steep slopes into the river gorge from the nearby vent. The possible relocation of the FR channel would enhance the FR water quality, but disrupt the natural beauty of the diapir.

  • 14. Abouessa, A.
    et al.
    Morad, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    An integrated study of diagenesis and depositional facies in tidal sandstones: Hawaz Formation (middle Ordovician), Murzuq Basin, Libya2009In: Journal of Petroleum Geology, ISSN 0141-6421, E-ISSN 1747-5457, Vol. 32, no 1, p. 39-65Article in journal (Refereed)
  • 15.
    Abrahamsson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Sveriges lantbruksuniversitet.
    In situ-metoder för sanering av klorerade lösningsmedel: utvärdering med avseende på svenska förhållanden2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Currently, there are 428 areas contaminated with chlorinated solvents in Sweden. These substances have been used in Sweden’s industry as degreasing agents and solvents.Chlorinated solvents are more difficult to investigate and remediate compared to petroleum hydrocarbons, due to their complicated distribution in different media. Hence, it is important to increase the knowledge of remediation of chlorinated solvents. The remediation technology excavation is frequently used in Sweden for contaminated areas. Excavation means that soil is dug up and transported to treatment or landfills sites. Due to its climate impact, the use of more sustainable remediation technologies should be increased.

    This thesis aimed to evaluate in situ remediation technologies for soil and groundwater contaminated with chlorinated solvents with respect to functionality, sustainability, time and cost aspects. Furthermore, this thesis aimed to investigate which technologies are best suited for Swedish conditions. To evaluate suitability and functionality of remediation technologies,all technologies were described and a case study of five areas in Sweden contaminated with chlorinated solvents was conducted. The contaminant situation and site-specific conditions were described for each area. Thereafter, the evaluation and choice of remediation technology and remediation result were presented. The technologies studied in the case study were two types of chemical reduction, multi-phase extraction, biostimulation and thermal treatment.The five projects were then assessed using the Swedish Geotechnical Institute’s decision support tool for remediation technologies, SAMLA. The technologies were rated in SAMLA according to criteria related to environmental factors, social factors and costs. Furthermore,the remediation technologies were evaluated based on their strengths and limitations with respect to Swedish conditions, such as geology, climate and geochemistry. They were also evaluated based on their strengths and limitations according to implementation areas, cost,remediation time, energy consumption and use in Sweden.The assessment of the five projects in SAMLA produced similar results compared to previously conducted risk evaluations. The technologies that were chosen based on the risk evaluations were also rated highest in SAMLA. The choice of technology for each project was based on conditions for the area, such as geology and existing buildings. Conclusions were drawn indicating that all technologies can be implemented in Sweden with respect to geological conditions. However, site-specific conditions, such as high groundwater flow and heterogeneous soil, limit the implementation of a specific technology. Moreover, other sitespecific conditions than those already discussed have to be considered, for instance buildings or future exploitation. Future development of in situ remediation technologies may focus on implementation of a certain type of geology (highly permeable soils), where chlorinated solvents may be found more frequently.

  • 16.
    Abrahamsson, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Ekelund, My
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Human Exposure from Mercury in Rice in the Philippines2015Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the western part of the Philippines, in the Palawan province, studies have shown that large quantities of mercury are spread to the surrounding area during heavy rainfall. In addition, mercury is spread to rice fields and bioaccumulated in marine fish and seafood. The mercury originates from the abandoned Palawan Quicksilver Mine. Since mercury is toxic for the human body and new studies have shown that mercury accumulates in rice, it is important to investigate human exposure from mercury in rice.

    This project investigates the total amount of mercury and methylmercury (MeHg) accumulated in rice, soil and water from four different rice fields in Palawan. The soil samples have been taken directly from the fields and water samples have been taken from nearby streams and springs. Rice grains harvested earlier this year from the same fields have been collected from farmers. The soil, water and rice samples were analyzed in Manila and rice samples were as well analyzed in Sweden and China. Furthermore, this project contains a dietary survey and calculation of daily exposure values of MeHg. The survey investigates how often people eat fish and rice and if they have dental amalgam. It also investigates possible health problems related to mercury exposure from rice and fish consumption.

    The analyses from China show that rice samples from all barangays contain total mercury and MeHg. Analyses from Sweden also show that rice from the barangays contains total mercury but the levels were found to be higher than the ones analyzed in China. Furthermore, the health problems found in the diet survey were hard to relate to mercury exposure from rice since the health problems can be caused by other factors. When calculating daily exposure values, the values were found to be as high as the recommended maximum acceptable daily intake in one of the barangays. There might therefore be a risk of eating rice from these four barangays. It is important to consider that these daily exposure values were only based on MeHg exposure from rice consumption, not taking dental amalgam and fish consumption into consideration. This means that the daily exposure values might be even higher than the ones calculated in this study.

  • 17.
    Abrate, Matteo
    et al.
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Bacciu, Clara
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Hast, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Marchetti, Andrea
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Minutoli, Salvatore
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Tesconi, Maurizio
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Geomemories - A Platform for Visualizing Historical, Environmental and Geospatial Changes of the Italian Landscape2013In: ISPRS International Journal of Geo-Information. Special issue: Geospatial Monitoring and Modelling of Environmental Change, ISSN 2220-9964, Vol. 2, no 2, p. 432-455Article in journal (Refereed)
    Abstract [en]

    The GeoMemories project aims at publishing on the Web and digitally preserving historical aerial photographs that are currently stored in physical form within the archives of the Aerofototeca Nazionale in Rome. We describe a system, available at http://www.geomemories.org, that lets users visualize the evolution of the Italian landscape throughout the last century. The Web portal allows comparison of recent satellite imagery with several layers of historical maps, obtained from the aerial photos through a complex workflow that merges them together. We present several case studies carried out in collaboration with geologists, historians and archaeologists, that illustrate the great potential of our system in different research fields. Experiments and advances in image processing technologies are envisaged as a key factor in solving the inherent issue of vast amounts of manual work, from georeferencing to mosaicking to analysis.

  • 18.
    Abreu, Rafael
    et al.
    Westfalische Wilhelms Univ Munster, Inst Geophys, Corrensstr 24, D-48149 Munster, Germany.;Univ Granada, Inst Andaluz Geofis, Campus Cartuja S-N, E-18071 Granada, Spain..
    Kamm, Jochen
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics. Westfalische Wilhelms Univ Munster, Inst Geophys, Corrensstr 24, D-48149 Munster, Germany.
    Reiss, Anne-Sophie
    Westfalische Wilhelms Univ Munster, Inst Geophys, Corrensstr 24, D-48149 Munster, Germany..
    Micropolar modelling of rotational waves in seismology2017In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 210, no 2, p. 1021-1046Article in journal (Refereed)
    Abstract [en]

    In this contribution we study elastic wave propagation via the introduction of the micropolar theory. As a generalization of a classical linear elastic medium, a micropolar medium allows each particle to have intrinsic rotational degrees of freedom (spin). We perform numerical experiments using the Pseudospectral method. We find analytical harmonic micropolar solutions for different problem configurations, which result in waveform differences between the classical linear elastic and micropolar media. In contrast to linear elastic media, wave propagation in micropolar media is dispersive. We study how the spin waveform depends on the micropolar elastic parameters and frequency content of the simulation. The micropolar effect on numerical seismograms has a direct implication on the phase, amplitude and arrival time. For frequencies lower than the cut-off frequency, the spin waveform has the same amplitude as the macrorotation field. For frequencies higher than the cut-off frequency, the amplitude of the spin waveform decreases with increasing frequency, so that then it is no longer comparable to the amplitude of macroscopic rotations. When both frequencies are equal there is no wave propagation. This work attempts to clarify the theory of micropolar media for its applications in seismology. We argue that micropolar theory should be further investigated for its potential uses in seismology to, for example, describe energy dissipation, seismograms recorded with rotational seismometers and rupture processes.

  • 19.
    Abril, Claudia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Gudmundsson, Ólafur
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Relocating earthquakes with empirical traveltimes2018In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 214, no 3, p. 2098-2114Article in journal (Refereed)
    Abstract [en]

    A strategy is proposed to incorporate effects of 3-D velocity variations on earthquake locationsusing empirical traveltimes (ETTs). Traveltime residuals are interpolated from those predictedusing a 1-D velocity reference, mapped on to the hypocentres of corresponding earthquakesfor each station in a network. First, station corrections are computed by averaging the residualsover a fixed scale. Then, summary-ray variograms are used to estimate uncertainty and that,in turn, is used to tune a local fit to neighbouring residuals to refine the corrections. Resulting3-D traveltime estimates are then used as a description of the forward problem in a nonlineargrid-search relocation. Data are weighted according to the estimated uncertainty. Data fromthe Icelandic Southern Iceland Lowlands (SIL) national seismic network are used to test thestrategy. ETTs are estimated forP- andS-waves at 65 stations in the SIL network, basedon four million arrival time readings of 300.000 events registered between 1990 and 2012.ETTs are strongly correlated for the two wave types. The spatial variations of the predictedcorrections are consistently comparable or somewhat less forS-waves thanP-waves. Thisfeature suggests variations of theVP/VSratio in the Icelandic crust. Error estimates are alsostrongly correlated for the two wave types and between nearby stations. Relocations aretested by comparison with explosions and small populations of well-located events withindenser subnetworks. Relocations result in modestly enhanced clustering of explosions andearthquakes and significantly improved depth estimates. Estimates of the random relocationerror are statistically better behaved than those of the SIL system. They are in general reduced,as is expected since 3-D heterogeneity is now partly taken into account.

  • 20.
    Abril, Claudia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Mai, Martin
    King Abdullah University of Science and Technology.
    Jonsson, Sigurjon
    King Abdullah University of Science and Technology.
    Ground-motion simulations around the Husavik-Flatey Fault, North IcelandManuscript (preprint) (Other academic)
  • 21.
    Abril, Claudia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Tryggvason, Ari
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Gudmundsson, Ólafur
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Steffen, Rebekka
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Local earthquake tomography and earthquake relocation in the Tjörnes Fracture Zone (North Iceland)Manuscript (preprint) (Other academic)
  • 22.
    Abtahi, Sayyed Mohammad
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Airborne Gravity Gradient, Magnetic and VLF datasets: Case studies of modelling, inversion and interpretation2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Northern Sweden is one of the largest hosts for mineral resources in Europe and always has been an interesting area for researchers from various disciplines of Earth sciences. This dissertation is a comprehensive summary of three case study papers on airborne VLF, gravity gradient and magnetic data in the area.

    In the first paper, tensor VLF data is extracted from an old data set which contains only the total and the vertical magnetic components. The anomalous part of the horizontal magnetic field components is computed by a Hilbert transform of the vertical magnetic field. The normal part of the horizontal magnetic field component is computed as a function of total, vertical and anomalous part of horizontal magnetic fields. The electric field is also calculated for TE mode and impedance tensor and apparent resistivity are computed. In addition tippers are calculated for two transmitters and inverted by a 3D inversion algorithm. Comparison of the estimated model and geology map of bedrock shows that lower resistivity zones are correlated with mineralizations.

    The second paper deals with the internal consistency of airborne gravity gradient data. The six components of the data are estimated from a common potential function. It is shown that the data is adequately consistent but at shorter land clearances the difference between the estimated data and the original data is larger. The technique is also used for computing the Bouguer anomaly from terrain corrected FTG data. Finally the data is inverted in 3D, which shows that the estimated density model in shallow depth is dominated by short wave length features.

    Inversion of TMI data is the topic of the third paper where a new type of reference model for 3D inversion of magnetic data is proposed by vertically extending the estimated magnetization of a 2D terrain magnetization model. The final estimated 3D result is compared with the magnetization model where no reference model is used. The comparison shows that using the reference model helps the high magnetization zones in the estimated model at shallow depths to be better correlated with measured high remanent magnetization from rock samples. The high magnetization zones are also correlated with gabbros and volcanic metasediments.

    List of papers
    1. Extracting geoelectrical maps from vintage very-low-frequency airborne data, tipper inversion, and interpretation: A case study from northern Sweden
    Open this publication in new window or tab >>Extracting geoelectrical maps from vintage very-low-frequency airborne data, tipper inversion, and interpretation: A case study from northern Sweden
    2016 (English)In: Geophysics, ISSN 0016-8033, E-ISSN 1942-2156, Vol. 81, no 5, p. B135-B147Article in journal (Refereed) Published
    Abstract [en]

    In 1985, the mining company Luossavaara-Kiirunavaara Aktiebolag collected airborne very-low-frequency (VLF) data in northern Sweden. The operators stored only the vertical component and the total magnetic field, which at that time were believed to be sufficient for qualitative interpretation. Therefore, the data could not be directly used for quantitative tensor VLF processing and inversion. To avoid the costs of resurveying, we have developed a novel technique to estimate the tippers from the measured VLF data by computing anomalous and normal parts of the horizontal components of the magnetic field from two transmitters separately. Retrieval of the normal horizontal components was possible because one component of the horizontal magnetic field was used as the phase reference during the measurements. Additionally, we have determined how the approximate apparent resistivity suitable for data visualization can be computed from the components of the magnetic field assuming an average normal resistivity of the subsurface. Maps of apparent resistivity combined with topography show a clear correlation between high topography and high resistivity, whereas conductive zones are found in valleys in between. More importantly, the 3D model inverted from the calculated tippers shows excellent agreement with a map of the surface geology. Based on this comparison, some less resistive zones can be related to fluids in fractures and others can be related to mineralized contact zones. We suggest to focus further exploration on conductive zones surrounding areas with basaltic composition.

    Place, publisher, year, edition, pages
    Uppsala: , 2016
    Keywords
    case history, inversion, interpretation, electromagnetics
    National Category
    Geophysics
    Identifiers
    urn:nbn:se:uu:diva-300086 (URN)10.1190/GEO2015-0296.1 (DOI)000392752200002 ()
    Available from: 2016-08-02 Created: 2016-08-02 Last updated: 2017-11-28Bibliographically approved
    2. Consistency investigation, vertical gravity estimation and inversion of airborne gravity gradient data – A case study from northern Sweden
    Open this publication in new window or tab >>Consistency investigation, vertical gravity estimation and inversion of airborne gravity gradient data – A case study from northern Sweden
    2016 (English)In: Geophysics, ISSN 0016-8033, E-ISSN 1942-2156, Vol. 81, no 3, p. B65-B76Article in journal (Refereed) Published
    Abstract [en]

    For airborne gravity gradient data, it is a challenge to distinguish between high-frequency intrinsic and dynamically produced noise caused by the aircraft and small-scale effects from shallow density variations. To facilitate consistent interpretation, techniques that include all of the measured gravity gradient components are particularly promising. We represented the measurements by a common potential function accounting for lateral and height variations. Thus, it was possible to evaluate the internal consistency between the measured components and to identify components with bias or particularly strong noise. As an extra benefit for data sets that contain terrain-corrected and nonterrain-corrected gravity gradient measurements at flight altitude, we estimated terrain-corrected anomalies on the topographic relief using downward continuation and retrieved nonterrain-corrected gravity gradient data suitable for inversion using upward continuation. For a field data set from northern Sweden, the largest differences (up to 50 eotvos) between the measured and estimated components of the gravity gradient data were found in areas of high topographical relief. But the average residual standard deviations of the individual components were between 3.6 and 7.4 eotvos, indicating that the components were consistent in an average sense. We have determined the successful conversion of terrain-corrected airborne gravity gradient data to Bouguer gravity data on the topographic relief using ground-based vertical gravity data as a reference. A 3D inverse model computed from the nonterrain-corrected data clearly showed the depth extent of the geologic structures observed at the surface, but it only produced a weak representation of the shallow structure. In contrast, a 2D surface density model in which only lateral variations of density in the topographic relief was allowed exhibited more realistic density distributions in fair correlation with geology.

    Keywords
    gravity, modeling, noise, processing
    National Category
    Geophysics
    Identifiers
    urn:nbn:se:uu:diva-300024 (URN)10.1190/geo2014-0428.1 (DOI)000384984900008 ()
    Available from: 2016-08-02 Created: 2016-08-02 Last updated: 2017-11-28Bibliographically approved
    3. A new reference model for 3D inversion of airborne magnetic data in hilly terrain – a case study from northern Sweden
    Open this publication in new window or tab >>A new reference model for 3D inversion of airborne magnetic data in hilly terrain – a case study from northern Sweden
    (English)Article in journal (Refereed) Submitted
    National Category
    Geophysics
    Identifiers
    urn:nbn:se:uu:diva-300111 (URN)
    Available from: 2016-08-02 Created: 2016-08-02 Last updated: 2016-09-05
  • 23.
    Abtahi, Sayyed Mohammad
    et al.
    Isfahan Univ Technol, Dept Min Engn, Esfahan, Iran.
    Pedersen, Laust Börsting
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Kamm, Jochen
    Univ Munster, Dept Geophys, Munster, Germany.
    Kalscheuer, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    A new reference model for 3D inversion of airborne magnetic data in hilly terrain: A case study from northern Sweden2018In: Geophysics, ISSN 0016-8033, E-ISSN 1942-2156, Vol. 83, no 1, p. B1-B12Article in journal (Refereed)
    Abstract [en]

    The inherent nonuniqueness in modeling magnetic data can be partly reduced by adding prior information, either as mathematical constructs or simply as bounds on magnetization obtained from laboratory measurements. If a good prior model can be used as a reference model, then the quality of estimated models through an inverse approach can be greatly improved. But even though data on magnetic properties of rocks might exist, their distribution may often be quite irregular on local and regional scales, so that it is difficult to define representative classes of rock types suitable for constraining geophysical models of magnetization. We have developed a new way of constructing a reference model that varies only laterally and is confined to the part of the terrain that lies above the lowest topography in the area. To obtain this model, several estimated 2D magnetization distributions were constructed by data inversion as a function of the iteration number. Then, a suitable 2D model of the magnetization in the topography was chosen as a starting point for constructing a 3D reference model by modifying it with a vertical decay such that its average source depth was the same for all horizontal positions. The average source depth of the reference model was chosen to satisfy the average source depth obtained from analyzing the radial power spectrum of the area studied. Finally, the measured magnetic data were inverted in three dimensions using the given reference model. For a selected reference model, shallow structures indicated a better overall correlation with large remanent magnetizations measured on rock samples from the area. Throughout the entire model, the direction of magnetization was allowed to vary freely. We found that the Euclidean norm of the estimated model was reduced compared with the case where the magnetization direction was fixed.

  • 24.
    Abtahi, Sayyed Mohammad
    et al.
    Uppsala University.
    Pedersen, Laust
    Kamm, Jochen
    Kalscheuer, Thomas
    A new reference model for 3D inversion of airborne magnetic data in hilly terrain – a case study from northern SwedenArticle in journal (Refereed)
  • 25.
    Abtahi, Sayyed Mohammad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics. Isfahan Univ Technol, Dept Min Engn, Esfahan, Iran.
    Pedersen, Laust
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Kamm, Jochen
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Kalscheuer, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Consistency investigation, vertical gravity estimation and inversion of airborne gravity gradient data – A case study from northern Sweden2016In: Geophysics, ISSN 0016-8033, E-ISSN 1942-2156, Vol. 81, no 3, p. B65-B76Article in journal (Refereed)
    Abstract [en]

    For airborne gravity gradient data, it is a challenge to distinguish between high-frequency intrinsic and dynamically produced noise caused by the aircraft and small-scale effects from shallow density variations. To facilitate consistent interpretation, techniques that include all of the measured gravity gradient components are particularly promising. We represented the measurements by a common potential function accounting for lateral and height variations. Thus, it was possible to evaluate the internal consistency between the measured components and to identify components with bias or particularly strong noise. As an extra benefit for data sets that contain terrain-corrected and nonterrain-corrected gravity gradient measurements at flight altitude, we estimated terrain-corrected anomalies on the topographic relief using downward continuation and retrieved nonterrain-corrected gravity gradient data suitable for inversion using upward continuation. For a field data set from northern Sweden, the largest differences (up to 50 eotvos) between the measured and estimated components of the gravity gradient data were found in areas of high topographical relief. But the average residual standard deviations of the individual components were between 3.6 and 7.4 eotvos, indicating that the components were consistent in an average sense. We have determined the successful conversion of terrain-corrected airborne gravity gradient data to Bouguer gravity data on the topographic relief using ground-based vertical gravity data as a reference. A 3D inverse model computed from the nonterrain-corrected data clearly showed the depth extent of the geologic structures observed at the surface, but it only produced a weak representation of the shallow structure. In contrast, a 2D surface density model in which only lateral variations of density in the topographic relief was allowed exhibited more realistic density distributions in fair correlation with geology.

  • 26.
    Abtahi, Sayyed Mohammad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics. Isfahan Univ Technol, Dept Min Engn, Esfahan, Iran.
    Pedersen, Laust
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Kamm, Jochen
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics. Univ Munster, Dept Geophys, Munster, Germany.
    Kalscheuer, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Extracting geoelectrical maps from vintage very-low-frequency airborne data, tipper inversion, and interpretation: A case study from northern Sweden2016In: Geophysics, ISSN 0016-8033, E-ISSN 1942-2156, Vol. 81, no 5, p. B135-B147Article in journal (Refereed)
    Abstract [en]

    In 1985, the mining company Luossavaara-Kiirunavaara Aktiebolag collected airborne very-low-frequency (VLF) data in northern Sweden. The operators stored only the vertical component and the total magnetic field, which at that time were believed to be sufficient for qualitative interpretation. Therefore, the data could not be directly used for quantitative tensor VLF processing and inversion. To avoid the costs of resurveying, we have developed a novel technique to estimate the tippers from the measured VLF data by computing anomalous and normal parts of the horizontal components of the magnetic field from two transmitters separately. Retrieval of the normal horizontal components was possible because one component of the horizontal magnetic field was used as the phase reference during the measurements. Additionally, we have determined how the approximate apparent resistivity suitable for data visualization can be computed from the components of the magnetic field assuming an average normal resistivity of the subsurface. Maps of apparent resistivity combined with topography show a clear correlation between high topography and high resistivity, whereas conductive zones are found in valleys in between. More importantly, the 3D model inverted from the calculated tippers shows excellent agreement with a map of the surface geology. Based on this comparison, some less resistive zones can be related to fluids in fractures and others can be related to mineralized contact zones. We suggest to focus further exploration on conductive zones surrounding areas with basaltic composition.

  • 27.
    Abyaneh, Morteza Y
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Philosophy, Logic and Metaphysics.
    Electrocrystallization: Modelling and Its Applications2014In: Development in Electrochemistry: Science Inspired by Martin Fleischmann / [ed] Derek Pletcher, Zhong-Qun Tian and David E. Williams, John Wiley & Sons, 2014, 1, p. 49-64Chapter in book (Refereed)
    Abstract [en]

    Mathematical modeling of the electrocrystallization processes and its applications has long been a subject dear to Martin Fleischmann. The study of nucleation is fundamental to the understanding of crystallization. In the context of electrocrystallization, the terms can be applied to phase formation at preferred sites on the electrode surface and phase formation at surfaces without such sites. Two models of nucleation are presented: a heterogeneous model (nucleation on an indent); and a spherical-cap model representing homogeneous nucleation. The transients are recorded by applying a two-step potential profile to the working electrode. This procedure ensures the reduction of the initial falling background/charging current, so that the magnitude of this initial current cannot mask the very early stages of electrocrystallization. Martin sought to establish an approach to nucleation based on quantum electrodynamics.

  • 28.
    Acikkol, Naz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Testing the Cretaceous Diversity of Ichthyosaurs and Their Extinction Hypotheses Using a Quantitative Approach2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As portrayed in Before the Dinosaur: the Historical Significance of the Fossil Marine Reptiles, ichthyosaurs, as other Mesozoic marine amniotes, have been unfairly overshadowed by dinosaurs in both popular culture and the field of vertebrate palaeontology. Yet by the effort of dedicated researchers, work on these fish-like marine reptiles had never died out, and in fact a second wave of interest emerged in the late 20th century. Since then, research on ichthyosaurs has focused on discovery of new taxa, assessments of their palaeobiology, and quantitative analyses of their diversity. Despite ever-growing interests, patterns and mechanisms leading up to their extinction in the Cenomanian were insufficiently evaluated. In other words, hypotheses focusing on abrupt extinction linked to a crash in prey diversity, notably belemnites, over a catastrophic event at the end-Cenomanian remain poorly tested. The current project thus aims to test: 1) whether the Cretaceous diversity of ichthyosaurs reflects biological signals, and 2) correlation of their diversity with the diversity of Mesozoic cephalopods, such as belemnites and ammonites. In this regard, a species-level dataset of Cretaceous belemnites including belemnite-bearing formations was built to be employed together with the occurrence-based ichthyosaur and ammonite datasets in the same taxic level. Raw taxic counts, as observed diversities of the clades, were quantified in two different temporal scales, and compared with two sampling proxies. The model-based method was then applied to correct all taxic counts based on the two proxies in both time bins to acquire expected diversities of all the clades. Comparisons resulted in strong correlations between the clades’ observed diversities and proxies exposing biased patterns under the influence of sampling intensity. Whereas both observed and expected diversities show no evidence of a causal relationship between the predator and prey groups, suggesting that the latter’s diversity seems not being a parameter for the former’s, and thus being unsupportive for a prey-driven demise of the predator. Furthermore, the expected trend of ichthyosaurs indicates lower Albian diversity gradually declining towards their extinction in the Cenomanian, which appears to be contrasting with recent studies.

  • 29.
    Adamaki, Angeliki
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Seismicity Analyses Using Dense Network Data: Catalogue Statistics and Possible Foreshocks Investigated Using Empirical and Synthetic Data2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Precursors related to seismicity patterns are probably the most promising phenomena for short-term earthquake forecasting, although it remains unclear if such forecasting is possible. Foreshock activity has often been recorded but its possible use as indicator of coming larger events is still debated due to the limited number of unambiguously observed foreshocks. Seismicity data which is inadequate in volume or character might be one of the reasons foreshocks cannot easily be identified. One method used to investigate the possible presence of generic seismicity behavior preceding larger events is the aggregation of seismicity series. Sequences preceding mainshocks chosen from empirical data are superimposed, revealing an increasing average seismicity rate prior to the mainshocks. Such an increase could result from the tendency of seismicity to cluster in space and time, thus the observed patterns could be of limited predictive value. Randomized tests using the empirical catalogues imply that the observed increasing rate is statistically significant compared to an increase due to simple clustering, indicating the existence of genuine foreshocks, somehow mechanically related to their mainshocks. If network sensitivity increases, the identification of foreshocks as such may improve. The possibility of improved identification of foreshock sequences is tested using synthetic data, produced with specific assumptions about the earthquake process. Complications related to background activity and aftershock production are investigated numerically, in generalized cases and in data-based scenarios. Catalogues including smaller, and thereby more, earthquakes can probably contribute to better understanding the earthquake processes and to the future of earthquake forecasting. An important aspect in such seismicity studies is the correct estimation of the empirical catalogue properties, including the magnitude of completeness (Mc) and the b-value. The potential influence of errors in the reported magnitudes in an earthquake catalogue on the estimation of Mc and b-value is investigated using synthetic magnitude catalogues, contaminated with Gaussian error. The effectiveness of different algorithms for Mc and b-value estimation are discussed. The sample size and the error level seem to affect the estimation of b-value, with implications for the reliability of the assessment of the future rate of large events and thus of seismic hazard.

    List of papers
    1. EVIDENCE OF PRECURSORY PATTERNS IN AGGREGATED TIME SERIES
    Open this publication in new window or tab >>EVIDENCE OF PRECURSORY PATTERNS IN AGGREGATED TIME SERIES
    2016 (English)In: Bulletin of the Geological Society of Greece, vol. L, 2016, Proceedings of the 14th Intern. Congress, Thessaloniki, May 2016, 2016, Vol. 50Conference paper, Published paper (Refereed)
    Abstract [en]

    We investigate temporal changes in seismic activity observed in the West Corinth Gulfand North-West Peloponnese during 2008 to 2010. Two major earthquake sequencestook place in the area at that time (in 2008 and 2010). Our aim is to analyse Greekseismicity to attempt to confirm the existence or non-existence of seismic precursorsprior to the strongest earthquakes. Perhaps because the area is geologically andtectonically complex, we found that it was not possible to fit the data well using aconsistent Epidemic Type Aftershock Sequence (ETAS) model. Nor could weunambiguously identify foreshocks to individual mainshocks. Therefore we soughtpatterns in aggregated foreshock catalogues. We set a magnitude threshold (M3.5)above which all the earthquakes detected in the study area are considered as“mainshocks”, and we combined all data preceding these into a single foreshockcatalogue. This reveals an increase in seismicity rate not robustly observable forindividual cases. The observed effect is significantly greater than that consistent withstochastic models, including ETAS, thus indicating genuine foreshock activity withpotential useful precursory power, if sufficient data is available, i.e. if the magnitudeof completeness is sufficiently low.

    Abstract [el]

    Μελετάμε χρονικές μεταβολές της σεισμικής δραστηριότητας στο Δυτικό ΚορινθιακόΚόλπο και τη Βορειοδυτική Πελοπόννησο κατά τα έτη 2008-2010. Δύο σημαντικέςσεισμικές ακολουθίες σημειώθηκαν στην περιοχή σε αυτή την περίοδο (2008 και 2010).Στόχος είναι να αναλύσουμε τη σεισμικότητα ώστε να επιβεβαιώσουμε την ύπαρξη ή μηπροσεισμικής δραστηριότητας πριν από τους μεγαλύτερους σεισμούς. Λόγω τηςγεωλογικής και τεκτονικής πολυπλοκότητας της περιοχής, δεν ήταν εφικτή η εφαρμογήενός ενιαίου μοντέλου Επιδημικού Τύπου Μετασεισμικών Ακολουθιών (ETAS), ούτε ηαναγνώριση προσεισμών μεμονωμένων κυρίων σεισμών. Επομένως, αναζητήσαμεανάλογα μοτίβα σε ενιαίους καταλόγους προσεισμών. Θέσαμε ένα μέγεθος (Μ3.5)πάνω από το οποίο όλοι οι σεισμοί θεωρούνται “κύριοι”, και συνδυάσαμε τα δεδομέναπου προηγούνται αυτών, σε ένα κοινό κατάλογο. Αναδεικνύεται έτσι μια αύξηση τουρυθμού σεισμικότητας που δεν είναι εμφανής σε μεμονωμένες περιπτώσεις και είναι πιοσημαντική από εκείνη που προβλέπεται από στοχαστικά μοντέλα, όπως το ETAS,υποδηλώνοντας την ύπαρξη προσεισμών που μπορούν να δώσουν τη δυνατότηταπρόγνωσης αν υπάρχει ικανοποιητικό πλήθος δεδομένων, δηλ. αν το μέγεθοςπληρότητας είναι αρκετά χαμηλό.

    Keywords
    Corinth Gulf, Seismicity, Aggregated Foreshock Catalogues, Κορινθιακός Κόλπος, Σεισμικότητα, Ενιαίοι Κατάλογοι Προσεισμών
    National Category
    Natural Sciences Geophysics
    Identifiers
    urn:nbn:se:uu:diva-295440 (URN)
    Conference
    14th International Congress, Geological Society of Greece, Thessaloniki, May 2016
    Available from: 2016-06-07 Created: 2016-06-07 Last updated: 2017-08-21Bibliographically approved
    2. Precursory Activity Before Larger Events in Greece Revealed by Aggregated Seismicity Data
    Open this publication in new window or tab >>Precursory Activity Before Larger Events in Greece Revealed by Aggregated Seismicity Data
    2017 (English)In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 174, no 3, p. 1331-1343Article in journal (Refereed) Published
    Abstract [en]

    We investigate the seismicity rate behaviour in and around Greece during 2009, seeking significant changes in rate preceding larger events. For individual larger events it is difficult to clearly distinguish precursory rate changes from other, possibly unrelated, variations in seismicity. However, when we aggregate seismicity data occurring within a radius of 10 km and in a 50-day window prior to earthquakes with, e. g. magnitude C3.5, the resulting aggregated time series show a clearly increasing trend starting 2-3 weeks prior to the "mainshock'' time. We apply statistical tests to investigate if the observed behaviour may be simply consistent with random (poissonian) variations, or, as some earlier studies suggest, with clustering in the sense that high activity rates at some time may imply increased rates later, and thus (randomly) greater probability of larger coming events than for periods of lower seismicity. In this case, rate increases have little useful predictive power. Using data from the entire catalogue, the aggregated rate changes before larger events are clearly and strongly statistically significant and cannot be explained by such clustering. To test this we choose events at random from the catalogue as potential "mainshocks''. The events preceding the randomly chosen earthquakes show less pronounced rate increases compared to the observed rate changes prior to larger events. Similar behaviour is observed in data sub-sets. However, statistical confidence decreases for geographical subsets containing few "mainshocks'' as it does when data are weighted such that "mainshocks'' with many preceding events are strongly downweighted relative to those with fewer. The analyses suggest that genuine changes in aggregated rate do occur prior to larger events and that this behaviour is not due to a small number of mainshocks with many preceding events dominating the analysis. It does not automatically follow that it will be possible to routinely observe precursory changes prior to individual larger events, but there is a possibility that this may be feasible, e. g. with better data from more sensitive networks.

    Place, publisher, year, edition, pages
    SPRINGER BASEL AG, 2017
    Keywords
    Temporal seismicity patterns, aggregated data, precursory activity, Greece
    National Category
    Geophysics
    Identifiers
    urn:nbn:se:uu:diva-320921 (URN)10.1007/s00024-017-1465-6 (DOI)000396834700039 ()
    Available from: 2017-04-27 Created: 2017-04-27 Last updated: 2017-08-21Bibliographically approved
    3. Advantages and Limitations of Foreshock Activity as a Useful Tool for Earthquake Forecasting
    Open this publication in new window or tab >>Advantages and Limitations of Foreshock Activity as a Useful Tool for Earthquake Forecasting
    (English)Manuscript (preprint) (Other academic)
    Keywords
    Accelerating Seismicity, Earthquake Predictability
    National Category
    Geophysics
    Research subject
    Geophysics with specialization in Seismology
    Identifiers
    urn:nbn:se:uu:diva-328055 (URN)
    Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-21
    4. Impact of Magnitude Uncertainties on Seismic Catalogue Properties
    Open this publication in new window or tab >>Impact of Magnitude Uncertainties on Seismic Catalogue Properties
    Show others...
    (English)In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246XArticle in journal (Refereed) Submitted
    Keywords
    Statistical Seismology, Earthquake Catalogue Properties, Completeness Magnitude, b-value
    National Category
    Earth and Related Environmental Sciences
    Research subject
    Statistics; Geophysics with specialization in Seismology
    Identifiers
    urn:nbn:se:uu:diva-328053 (URN)
    Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-08-21
  • 30.
    Adamaki, Angeliki K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Roberts, Roland G.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Precursory Activity Before Larger Events in Greece Revealed by Aggregated Seismicity Data2017In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 174, no 3, p. 1331-1343Article in journal (Refereed)
    Abstract [en]

    We investigate the seismicity rate behaviour in and around Greece during 2009, seeking significant changes in rate preceding larger events. For individual larger events it is difficult to clearly distinguish precursory rate changes from other, possibly unrelated, variations in seismicity. However, when we aggregate seismicity data occurring within a radius of 10 km and in a 50-day window prior to earthquakes with, e. g. magnitude C3.5, the resulting aggregated time series show a clearly increasing trend starting 2-3 weeks prior to the "mainshock'' time. We apply statistical tests to investigate if the observed behaviour may be simply consistent with random (poissonian) variations, or, as some earlier studies suggest, with clustering in the sense that high activity rates at some time may imply increased rates later, and thus (randomly) greater probability of larger coming events than for periods of lower seismicity. In this case, rate increases have little useful predictive power. Using data from the entire catalogue, the aggregated rate changes before larger events are clearly and strongly statistically significant and cannot be explained by such clustering. To test this we choose events at random from the catalogue as potential "mainshocks''. The events preceding the randomly chosen earthquakes show less pronounced rate increases compared to the observed rate changes prior to larger events. Similar behaviour is observed in data sub-sets. However, statistical confidence decreases for geographical subsets containing few "mainshocks'' as it does when data are weighted such that "mainshocks'' with many preceding events are strongly downweighted relative to those with fewer. The analyses suggest that genuine changes in aggregated rate do occur prior to larger events and that this behaviour is not due to a small number of mainshocks with many preceding events dominating the analysis. It does not automatically follow that it will be possible to routinely observe precursory changes prior to individual larger events, but there is a possibility that this may be feasible, e. g. with better data from more sensitive networks.

  • 31.
    Adamaki, Angeliki
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Roberts, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Advantages and Limitations of Foreshock Activity as a Useful Tool for Earthquake ForecastingManuscript (preprint) (Other academic)
  • 32.
    Adamaki, Angeliki
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Roberts, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    EVIDENCE OF PRECURSORY PATTERNS IN AGGREGATED TIME SERIES2016In: Bulletin of the Geological Society of Greece, vol. L, 2016, Proceedings of the 14th Intern. Congress, Thessaloniki, May 2016, 2016, Vol. 50Conference paper (Refereed)
    Abstract [en]

    We investigate temporal changes in seismic activity observed in the West Corinth Gulfand North-West Peloponnese during 2008 to 2010. Two major earthquake sequencestook place in the area at that time (in 2008 and 2010). Our aim is to analyse Greekseismicity to attempt to confirm the existence or non-existence of seismic precursorsprior to the strongest earthquakes. Perhaps because the area is geologically andtectonically complex, we found that it was not possible to fit the data well using aconsistent Epidemic Type Aftershock Sequence (ETAS) model. Nor could weunambiguously identify foreshocks to individual mainshocks. Therefore we soughtpatterns in aggregated foreshock catalogues. We set a magnitude threshold (M3.5)above which all the earthquakes detected in the study area are considered as“mainshocks”, and we combined all data preceding these into a single foreshockcatalogue. This reveals an increase in seismicity rate not robustly observable forindividual cases. The observed effect is significantly greater than that consistent withstochastic models, including ETAS, thus indicating genuine foreshock activity withpotential useful precursory power, if sufficient data is available, i.e. if the magnitudeof completeness is sufficiently low.

  • 33. Adamczyk, A.
    et al.
    Malinowski, M.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    High-resolution near-surface velocity model building using full-waveform inversion-a case study from southwest Sweden2014In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 197, no 3, p. 1693-1704Article in journal (Refereed)
    Abstract [en]

    Full-waveform inversion (FWI) is an iterative optimization technique that provides high-resolution models of subsurface properties. Frequency-domain, acoustic FWI was applied to seismic data acquired over a known quick-clay landslide scar in southwest Sweden. We inverted data from three 2-D seismic profiles, 261-572 m long, two of them shot with small charges of dynamite and one with a sledgehammer. To our best knowledge this is the first published application of FWI to sledgehammer data. Both sources provided data suitable for waveform inversion, the sledgehammer data containing even wider frequency spectrum. Inversion was performed for frequency groups between 27.5 and 43.1 Hz for the explosive data and 27.5-51.0 Hz for the sledgehammer. The lowest inverted frequency was limited by the resonance frequency of the standard 28-Hz geophones used in the survey. High-velocity granitic bedrock in the area is undulated and very shallow (15-100 m below the surface), and exhibits a large P-wave velocity contrast to the overlying normally consolidated sediments. In order to mitigate the non-linearity of the inverse problem we designed a multiscale layer-stripping inversion strategy. Obtained P-wave velocity models allowed to delineate the top of the bedrock and revealed distinct layers within the overlying sediments of clays and coarse-grained materials. Models were verified in an extensive set of validating procedures and used for pre-stack depth migration, which confirmed their robustness.

  • 34.
    Adamczyk, Anna
    et al.
    Institute of Geophysics - Polish Academy of Sciences.
    Malinowski, Michal
    Institute of Geophysics - Polish Academy of Sciences.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Delineating shallow quick-clay structures using acoustic full-waveform inversion – case studyfrom southwest Sweden2013Conference paper (Refereed)
    Abstract [en]

    Full waveform inversion (FWI) was applied to imageshallow structures of marine-clay sediments and to provideinsight on the mechanism of a quick-clay landslide. Thedata was acquired in a high-resolution seismic surveyconducted over a known landslide scar near the Göta riverin southwest Sweden. Inversion proved to be challengingbecause of contrasted P-wave velocity structure – thevelocities ranged from 500 m/s in weathered top layer to6000 m/s in the shallow granitic bedrock (up to 30 m belowthe surface). FWI applied to 3 profiles provided highresolution2D P-wave velocity models revealing theintercalating layers of clays and coarse-grain material andthe shape of the bedrock. The multiscale approach was usedto mitigate the strong nonlinearity of the inverse problem.The models were used in pre-stack depth migration andproved significant improvement in reflector flattening andfocusing over the starting first-arrival traveltimetomography models.

  • 35.
    Adamsson, Karolin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Kollektivtrafikknutpunkter i Göteborg ur ett genusperspektiv2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper will examine two public transportation hubs, as examples of public space, in Gothenburg, Sweden, from a gender perspective by investigate how gender equality is discussed in planning processes of hubs and to explore how hubs are used and perceived by men and women. The thesis has a qualitative and hermeneutic approach, with semi-structured interviews with key persons from the planning processes, and site observations and interviews with men and women using the hubs as the main data gathering methods. In the planning processes for the two cases the ambition was to create hubs that were welcoming for everyone, from a theoretical point of view this ambition could be dangerous from a gender perspective since a planning for everyone often leads to a planning for the man. In order to create hubs for everyone there was a focus for creating safety and increase accessibility for the disabled during the planning processes. The observations and the interviews on site shows that the hubs could be viewed as gender equal since the hubs were open to both men and women to use, but the hubs could also be viewed as not gender equal since women felt unsafe. The analysis shows that the social interaction on site is a crucial factor when defining a place as gender equal or not. The social interaction can be understood by gender contract. One conclusion is that there is a need for discussions about gender and its effect on experiences of public space, where gender contract is problematized. It will otherwise be hard to understand and change the interaction and the gender inequality will risk to consolidate.

  • 36.
    Addor, Nans
    et al.
    Univ Zurich, Dept Geog, Zurich, Switzerland.;Natl Ctr Atmospher Res, Appl Res Lab, POB 3000, Boulder, CO 80307 USA..
    Rohrer, Marco
    Univ Bern, Oeschger Ctr Climate Change Res, Bern, Switzerland.;Univ Bern, Inst Geog, Bern, Switzerland..
    Furrer, Reinhard
    Univ Zurich, Dept Math, Zurich, Switzerland..
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Zurich, Dept Geog, Zurich, Switzerland..
    Propagation of biases in climate models from the synoptic to the regional scale: Implications for bias adjustment2016In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 121, no 5, p. 2075-2089Article in journal (Refereed)
    Abstract [en]

    Bias adjustment methods usually do not account for the origins of biases in climate models and instead perform empirical adjustments. Biases in the synoptic circulation are for instance often overlooked when postprocessing regional climate model (RCM) simulations driven by general circulation models (GCMs). Yet considering atmospheric circulation helps to establish links between the synoptic and the regional scale, and thereby provides insights into the physical processes leading to RCM biases. Here we investigate how synoptic circulation biases impact regional climate simulations and influence our ability to mitigate biases in precipitation and temperature using quantile mapping. We considered 20 GCM-RCM combinations from the ENSEMBLES project and characterized the dominant atmospheric flow over the Alpine domain using circulation types. We report in particular a systematic overestimation of the frequency of westerly flow in winter. We show that it contributes to the generalized overestimation of winter precipitation over Switzerland, and this wet regional bias can be reduced by improving the simulation of synoptic circulation. We also demonstrate that statistical bias adjustment relying on quantile mapping is sensitive to circulation biases, which leads to residual errors in the postprocessed time series. Overall, decomposing GCM-RCM time series using circulation types reveals connections missed by analyses relying on monthly or seasonal values. Our results underscore the necessity to better diagnose process misrepresentation in climate models to progress with bias adjustment and impact modeling.

  • 37. Addor, Nans
    et al.
    Rössler, Ole
    Köplin, Nina
    Huss, Matthias
    Weingartner, Rolf
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Robust changes and sources of uncertainty in the projected hydrological regimes of Swiss catchments2014In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 50, no 10, p. 7541-7562Article in journal (Refereed)
    Abstract [en]

    Projections of discharge are key for future water resources management. These projections are subject to uncertainties, which are difficult to handle in the decision process on adaptation strategies. Uncertainties arise from different sources such as the emission scenarios, the climate models and their postprocessing, the hydrological models, and the natural variability. Here we present a detailed and quantitative uncertainty assessment, based on recent climate scenarios for Switzerland (CH2011 data set) and covering catchments representative for midlatitude alpine areas. This study relies on a particularly wide range of discharge projections resulting from the factorial combination of 3 emission scenarios, 10–20 regional climate models, 2 postprocessing methods, and 3 hydrological models of different complexity. This enabled us to decompose the uncertainty in the ensemble of projections using analyses of variance (ANOVA). We applied the same modeling setup to six catchments to assess the influence of catchment characteristics on the projected streamflow, and focused on changes in the annual discharge cycle. The uncertainties captured by our setup originate mainly from the climate models and natural climate variability, but the choice of emission scenario plays a large role by the end of the 21st century. The contribution of the hydrological models to the projection uncertainty varied strongly with catchment elevation. The discharge changes were compared to the estimated natural decadal variability, which revealed that a climate change signal emerges even under the lowest emission scenario (RCP2.6) by the end of the century. Limiting emissions to RCP2.6 levels would nevertheless reduce the largest regime changes by the end of the century by approximately a factor of two, in comparison to impacts projected for the high emission scenario SRES A2. We finally show that robust regime changes emerge despite the projection uncertainty. These changes are significant and are consistent across a wide range of scenarios and catchments. We propose their identification as a way to aid decision making under uncertainty.

  • 38. Addor, Nans
    et al.
    Seibert, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Bias correction for hydrological impact studies: beyond the daily perspective2014In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, no 17, p. 4823-4828Article in journal (Other academic)
  • 39. Adinugroho, Sigit
    et al.
    Vallot, Dorothée
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Westrin, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Strand, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Calving events detection and quantification from time-lapse images in Tunabreen glacier2015In: Proc. 9th International Conference on Information & Communication Technology and Systems, Piscataway, NJ: IEEE , 2015, p. 61-65Conference paper (Refereed)
  • 40. Adolphi, Florian
    et al.
    Muscheler, Raimund
    Svensson, Anders
    Aldahan, Ala
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Beer, Jurg
    Sjolte, Jesper
    Bjorck, Svante
    Matthes, Katja
    Thieblemont, Remi
    Persistent link between solar activity and Greenland climate during the Last Glacial Maximum2014In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 7, no 9, p. 662-666Article in journal (Refereed)
    Abstract [en]

    Changes in solar activity have previously been proposed to cause decadal- to millennial-scale fluctuations in both the modern and Holocene climates(1). Direct observational records of solar activity, such as sunspot numbers, exist for only the past few hundred years, so solar variability for earlier periods is typically reconstructed from measurements of cosmogenic radionuclides such as Be-10 and C-14 from ice cores and tree rings(2,3). Here we present a high-resolution Be-10 record from the ice core collected from central Greenland by the Greenland Ice Core Project (GRIP). The record spans from 22,500 to 10,000 years ago, and is based on new and compiled data(4-6). Using C-14 records(7,8) to control for climate-related influences on Be-10 deposition, we reconstruct centennial changes in solar activity. We find that during the Last Glacial Maximum, solar minima correlate with more negative delta O-18 values of ice and are accompanied by increased snow accumulation and sea-salt input over central Greenland. We suggest that solar minima could have induced changes in the stratosphere that favour the development of high-pressure blocking systems located to the south of Greenland, as has been found in observations and model simulations for recent climate(9,10). We conclude that the mechanism behind solar forcing of regional climate change may have been similar under both modern and Last Glacial Maximum climate conditions.

  • 41.
    Adrian, Lindqvist
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Koppling av grundvattenmodell och jordmodell med en geoteknisk sättningsmodell2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    From a construction engineering point of view groundwater drawdown in a confined aquifer can result in ground subsidence that can damage buildings and constructions. The connection between hydrogeology and soil mechanics is clear, however when estimating ground settlement as a result of groundwater drawdown the estimations are often rough. This is due to that settlement is traditionally calculated with methods that only allow calculations in single points where geotechnical data is estimated. Areas between these points are often left out of the calculations. Groundwater drawdown is seldom simulated with acknowledged software programs like Modflow when estimating groundwater lowering and the affected area.This study combines a groundwater model simulated in Modflow and a soil strata model, interpolated with Kriging, with settlement calculations. This ends up as a an integrated soil settlement model which has the purpose to generate overview maps over areas that are sensitive to settlement as a result of ground water lowering. The integrated model is programmed in Octave for this study. The model is then tested with a case study that uses data from a real construction project in the area of Mälardalen. A hypothetical case of ground water lowering is simulated for the case study. Fundamental hydro-geological theory is used to estimate loads and effective stresses from the lowering of the water table.The result from the integrated model has been validated against calculations of settlement in the software Geosuite Settlement which is an acknowledged method for settlement calculations. This shows that the integrated model calculates settlement with great precision. The modeled initial ground water table is compared with a kriginginterpolated groundwater table which is based on data from ground water pipes in the area. Based on the comparison the initial ground water conditions simulated in Modflow are accepted. This simulated ground water model has the soil model and also a water balance integrated.The results from the case study show that unexpectedly large ground settlements can occur even far from the source of the ground water lowering.For the case study three different soil models are used, both in the ground water model and in the integrated model. The soil models differ in a way that they are based on different amounts of data from which the kriging interpolation is done. The purpose for this is to investigate what effects this might have on the ground water model and the integrated model respectively. The results from these different simulations show insignificantly small differences.

  • 42. Adrian, Rita
    et al.
    O`Reilly, Catherine M.
    Zagarese, Horacio
    Baines, Stephen B.
    Hessen, Dag O.
    Keller, Wendel
    Livingstone, David M.
    Sommaruga, Ruben
    Straile, Dietmar
    Van Donk, Ellen
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Winder, Monika
    Lakes as sentinels of climate change2009In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 54, no 6(2), p. 2283-2297Article in journal (Refereed)
    Abstract [en]

    While there is a general sense that lakes can act as sentinels of climate change, their efficacy has not been thoroughly analyzed. We identified the key response variables within a lake that act as indicators of the effects of climate change on both the lake and the catchment. These variables reflect a wide range of physical, chemical, and biological responses to climate. However, the efficacy of the different indicators is affected by regional response to climate change, characteristics of the catchment, and lake mixing regimes. Thus, particular indicators or combinations of indicators are more effective for different lake types and geographic regions. The extraction of climate signals can be further complicated by the influence of other environmental changes, such as eutrophication or acidification, and the equivalent reverse phenomena, in addition to other land-use influences. In many cases, however, confounding factors can be addressed through analytical tools such as detrending or filtering. Lakes are effective sentinels for climate change because they are sensitive to climate, respond rapidly to change, and integrate information about changes in the catchment.

  • 43.
    Afsar, Fatima
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    ANALYSIS AND INTERPRETATION OF 2D/3D SEISMIC DATA OVER DHURNAL OIL FIELD, NORTHERN PAKISTAN2013Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The study area, Dhurnal oil field, is located 74 km southwest of Islamabad in the Potwar basin of Pakistan. Discovered in March 1984, the field was developed with four producing wells and three water injection wells. Three main limestone reservoirs of Eocene and Paleocene ages are present in this field. These limestone reservoirs are tectonically fractured and all the production is derived from these fractures. The overlying claystone formation of Miocene age provides vertical and lateral seal to the Paleocene and Permian carbonates. The field started production in May 1984, reaching a maximum rate of 19370 BOPD in November 1989. Currently Dhurnal‐1 (D-1) and Dhurnal‐6 (D-6) wells are producing 135 BOPD and 0.65 MMCF/D gas. The field has depleted after producing over 50 million Bbls of oil and 130 BCF of gas from naturally fractured low energy shelf carbonates of the Eocene, Paleocene and Permian reservoirs. Preliminary geological and geophysical data evaluation of Dhurnal field revealed the presence of an up-dip anticlinal structure between D-1 and D-6 wells, seen on new 2003 reprocessed data. However, this structural impression is not observed on old 1987 processed data. The aim of this research is to compare and evaluate old and new reprocessed data in order to identify possible factors affecting the structural configuration. For this purpose, a detailed interpretation of old and new reprocessed data is carried out and results clearly demonstrate that structural compartmentalization exists in Dhurnal field (based on 2003 data). Therefore, to further analyse the available data sets, processing sequences pertaining to both vintages have been examined. After great effort and detailed investigation, it is concluded that the major parameter giving rise to this data discrepancy is the velocity analysis done with different gridding intervals. The detailed and dense velocity analysis carried out on the data in 2003 was able to image the subtle anticlinal feature, which was missed on the 1987 processed seismic data due to sparse gridding. In addition to this, about 105 sq.km 3D seismic data recently (2009) acquired by Ocean Pakistan Limited (OPL) is also interpreted in this project to gain greater confidence on the results. The 3D geophysical interpretation confirmed the findings and aided in accurately mapping the remaining hydrocarbon potential of Dhurnal field.

  • 44. Aftabi, Pedram
    et al.
    Roustaie, Mahasa
    Alsop, G.Ian
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    InSAR mapping and modelling of an active Iranian salt extrusion2010In: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 167, no 1, p. 155-170Article in journal (Refereed)
    Abstract [en]

    Interferometric synthetic aperture radar (InSAR) imaging is a powerful technique that is increasingly used to extract detailed 3D information on Earth surface structures, including exposed diapiric surfaces. We have used InSAR to map, for the first time, the cumulative surface deformation in a 6 km × 3 6 km region surrounding an active salt diapir (Syahoo) and its associated surface salt flow (or namakier) exposed in the Zagros Mountains of southern Iran. Images provided by the European Space Agency were acquired in 12 increments (ranging in length between 35 and 1248 days) over a 14 year interval between July 1992 and May 2006. The deformation of the salt surface is non-steady, with (extrapolated) rates of displacement varying between surficial uplifts of +1.4 mm day-1 (+511 mm a-1) and subsidence of -2.2 mm day-1 (-803 mm a-1). Growth of a central topographic dome occurs following short wet intervals to create a salt fountain morphology, which then slowly decays during the intervening long dry periods. Salt associated with dynamic 'bulging' of the central dome during wet intervals may flow laterally via gravity spreading into the surrounding salt sheet, resulting in deflation and subsidence of the dome, which is counteracted by growth and inflation of the adjacent namakiers. Salt 'bulges' that migrate down the namakier, resulting in local inflationary and deflationary cycles of the surface, may be regarded as episodic pulses of gravity spreading. Areas of inflation and deflation are also observed to commonly reverse during dry to wet periods, as the overall salt system effectively self regulates as it continually strives for dynamic equilibrium. As long as the source of salt remains undepleted, gravity spreading of the dome ultimately results in more buoyancy-driven salt flowing up the diapiric neck to replenish and feed the extrusion and maintain the gross fountain morphology.

  • 45. Agapitov, Oleksiy
    et al.
    Krasnoselskikh, Vladimir
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Rolland, Guy
    A statistical study of the propagation characteristics of whistler waves observed by Cluster2011In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 38, p. L20103-Article in journal (Refereed)
    Abstract [en]

    VLF waves play a crucial role in the dynamics of radiation belts, and are responsible for the loss and the acceleration of energetic electrons. Modeling wave-particle interactions requires the best possible knowledge for how wave energy and wave-normal directions are distributed in L-shells and for the magnetic latitudes of different magnetic activity conditions. In this work, we performed a statistical study for VLF emissions using a whistler frequency range for nine years (2001-2009) of Cluster measurements. We utilized data from the STAFF-SA experiment, which spans the frequency range from 8.8 Hz to 3.56 kHz. We show that the wave energy distribution has two maxima around L similar to 4.5 = 6 and L similar to 2, and that wave-normals are directed approximately along the magnetic field in the vicinity of the geomagnetic equator. The distribution changes with magnetic latitude, and so that at latitudes of similar to 30 degrees, wave-normals become nearly perpendicular to the magnetic field. The observed angular distribution is significantly different from Gaussian and the width of the distribution increases with latitude. Since the resonance condition for wave-particle interactions depends on the wave normal orientation, our results indicate that, due to the observed change in the wave-normal direction with latitude, the most efficient particle diffusion due to wave-particle interaction should occur in a limited region surrounding the geomagnetic equator.

  • 46. Agerstrand, Marlene
    et al.
    Berg, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Environmental toxicology.
    Bjorlenius, Berndt
    Breitholtz, Magnus
    Brunström, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Environmental toxicology.
    Fick, Jerker
    Gunnarsson, Lina
    Larsson, D. G. Joakim
    Sumpter, John P.
    Tysklind, Mats
    Ruden, Christina
    Improving Environmental Risk Assessment of Human Pharmaceuticals2015In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 49, no 9, p. 5336-5345Article in journal (Refereed)
    Abstract [en]

    This paper presents 10 recommendations for improving the European Medicines Agency's guidance for environmental risk assessment of human pharmaceutical products. The recommendations are based on up-to-date, available science in combination with experiences from other chemical frameworks such as the REACH-legislation for industrial chemicals. The recommendations concern: expanding the scope of the current guideline; requirements to assess the risk for development of antibiotic resistance; jointly performed assessments; refinement of the test proposal; mixture toxicity assessments on active pharmaceutical ingredients with similar modes of action; use of all available ecotoxicity studies; mandatory reviews; increased transparency; inclusion of emission data from production; and a risk management option. We believe that implementation of our recommendations would strengthen the protection of the environment and be beneficial to society. Legislation and guidance documents need to be updated at regular intervals in order to incorporate new knowledge from the scientific community. This is particularly important for regulatory documents concerning pharmaceuticals in the environment since this is a research field that has been growing substantially in the last decades.

  • 47.
    Agic, Heda
    et al.
    Department of Earth Science, University of California at Santa Barbara, Santa Barbara, USA.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Högström, Anette
    Tromsø Universitetsmuseum.
    Ebbestad, Jan Ove R.
    Uppsala University, Music and Museums, Museum of Evolution.
    Jensen, Sören
    Área de Paleontología, Universidad de Extremadura, Avenida de Elvas s/n, Badajoz, Spain.
    Meinhold, Guido
    Geowissenschaftliches Zentrum der Universität Göttingen, Germany.
    Palacios, Teodor
    Área de Paleontología, Universidad de Extremadura, Avenida de Elvas s/n, Badajoz, Spain.
    Taylor, Wendy L.
    Department of Geological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
    Novis, Linn K.
    Tromsø Universitetsmuseum.
    Unusual organic-walled microfossil from the late Neoproterozoic Nyborg Formation, Digermulen Peninsula, Arctic Norway2017In: ISECT 2017, 2017Conference paper (Other academic)
    Abstract [en]

    The late Neoproterozoic Nyborg Formation is exposed in the Tanafjord area, Finnmark, Arctic Norway, on Digermulen and Varanger Peninsulas. The succession is composed of ~400 m of interbedded shales, siltstone and purple to grey sandstone, deposited between Neoproterozoic low latitude glacial deposits. The Nyborg Fm. lies on top of the Smalfjord diamictite, and is overlain by the Mortensnes diamictite (the latter was attributed to both Marinoan (650-635 Ma) and Gaskiers (579 Ma) glaciations) and the Ediacaran-Cambrian Stáhpogieddi Formation. Thus, the Nyborg Fm. represents late Neoproterozoic, probably the last Cryogenian interglacial interval. Presented material was collected in 2014 by members of Digermulen Early Life Research Group, from organic-rich, grey-green shales and siltstones of the Nyborg Mbr. D, uppermost Nyborg Fm. between Árasulluokta and Guvssájohka valleys. Organic-walled microfossils were extracted from shale via standard palynological acetolysis in hydrofluoric acid, and studied via light and scanning electron microscopy. Microfossils from the Nyborg Fm. include Synsphaeridium-type aggregated cells, unbranched bacterial filaments (Polythrichoides and Siphonophycus), sphaeromorph and envelope-bearing acritarchs (leiosphaerids, Stictosphaeridium, Simia), and previously unrecognized aggregated tubular microfossils. These taxa are long-ranging, but common in glacial-interglacial units worldwide, and thus broadly corroborate the Cryogenian age of the Nyborg sediments. The novel fossil, up to 300 μm in size, is a parenchymatous meshwork of interconnected organic-walled tubes that terminate in cup-shaped apices 4-11 µm in diameter. Irregular tube clusters are truncated both in macerates and in thin sections, suggesting post mortem transport. Elemental EDXS analysis indicates that extracted meshwork microfossils are predominantly composed of carbonaceous material and also associated with small amounts of titanium and vanadium. Considering the branching and adjoined body plan of carbonaceous fossil, it was likely multicellular and of eukaryotic affinity. As such, it may represent an important step in the evolution of complex multicellularity and morphological complexity several million years before the appearance of Ediacaran organisms.

  • 48.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    A new species of small acritarch with porous wall structure from the early Cambrian of Estonia, and implications for the fossil record of eukaryotic picoplankton2015In: Palynology, ISSN 0191-6122, E-ISSN 1558-9188, Vol. 40, no 3, p. 343-356Article in journal (Refereed)
    Abstract [en]

    The Proterozoic-Phanerozoic transition records a general trend of decrease in phytoplankton cell size, in contrast tothe earlier and much larger Ediacaran acritarchs. Particularly minute, unornamented but sculptured organic-walledmicrofossils have been recovered from the lower Cambrian Lükati Formation in northern Estonia. The lack of anysignificant thermal alteration in the formation allowed for excellent preservation of fine microstructures on thesemicrofossils. Among the rich palynomorph assemblage in Lükati, a new species of tiny, spheroidal eukaryoticmicrofossil is recorded: Reticella corrugata gen. et sp. nov. It is characterised by a corrugated and flexible vesicle wallthat is densely perforated by nano-scale pores. Despite its unique morphology, the new species shares diagnosticcharacters with fossil and extant prasinophyte algae. R. corrugata is among the smallest microfossils with typicaleukaryotic morphology (conspicuous wall sculpture) and contributes to the diversity of the size class of smallacritarchs. Size, abundance, inferred prasinophyte affinity and eukaryotic wall sculpture make this new taxon alikely member of the early eukaryotic picoplankton.

  • 49.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Fossil Focus: Acritarchs2016In: Palaeontology Online, Vol. 6, no 11, p. 1-13Article in journal (Other (popular science, discussion, etc.))
  • 50.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Microfossils of eukaryotic cysts through time: A study of Precambrian-Ordovician organic-walled microbiota2014Licentiate thesis, comprehensive summary (Other academic)
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