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  • 251. Breitbarth, Eike
    et al.
    Oschlies, A.
    National Oceanography Centre, Southampton, European Way, Southampton.
    LaRoche, J.
    Leibniz-Institute of Marine Sciences, IFM-GEOMAR, Dusternbrooker Weg 20, 24105 Kiel.
    Physiological constraints on the global distribution of Trichodesmium: effect of temperature on diazotrophy2007Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 4, nr 1, s. 53-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cyanobacterium Trichodesmium is an important link in the global nitrogen cycle due to its significant input of atmospheric nitrogen to the ocean. Attempts to incorporate Trichodesmium in ocean biogeochemical circulation models have, so far, relied on the observed correlation between temperature and Trichodesmium abundance. This correlation may result in part from a direct effect of temperature on Trichodesmium growth rates through the control of cellular biochemical processes, or indirectly through temperature influence on mixed layer depth, light and nutrient regimes. Here we present results indicating that the observed correlation of Trichodesmium with temperature in the field reflects primarily the direct physiological effects of temperature on diazotrophic growth of Trichodesmium. Trichodesmium IMS-101 (an isolate of T. erythraeum) could acclimate and grow at temperatures ranging from 20 to 34C.Maximum growth rates (μmax=0.25 day-1) and maximum nitrogen fixation rates (0.13 mmol N mol POC-1 h-1) were measured within 24 to 30C. Combining this empirical relationship with global warming scenarios derived from state-of-the-art climate models sets a physiological constraint on the future distribution of Trichodesmium that could significantly affect the future nitrogen input into oligotrophic waters by this diazotroph.

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  • 252.
    Brown, James R.
    Luleå tekniska universitet.
    Microearthquakes and seismic risk1978Ingår i: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 100, nr 3, s. 307-13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper is presented in the nature of a review of the potential of microearthquake surveys in seismotectonic studies, particularly seismic-risk analyses. Microearthquakes are generally considered as shocks with magnitude less than 3. They radiate, in general, higher frequencies than larger earthquakes and therefore microearthquake seismographs must be sensitive to frequencies typically up to 30 or 40 Hz. Mircroearthquakes are useful in seismotectonic studies because: (1) a greater number of small than large shocks occur in the same time, (2) extension to lower magnitudes of frequency-of-occurrence curves can yield more reliable seismic-risk statistics, (3) due to the reduced scale, both in space and time, very precise focal location is possible, often enabling mapping of fracture surfaces, (4) focal-mechanism solutions can further determine the fault surface and, in addition, the direction of slip, and (S) continuous monitoring of seismic activity is possible through the means of a permanent network of microearthquake systems.

  • 253.
    Brown, R.J.
    et al.
    Luleå tekniska universitet.
    Friesen, G.H.
    Gulf Oil, Canada.
    Hall, D.H.
    Department of Earth Sciences, University of Manitoba.
    Stephenson, O.G.
    Department of Earth Sciences, University of Manitoba.
    Weighted vertical stacking in crustal seismic reflection studies on the Canadian shield1977Ingår i: Geophysical Prospecting, ISSN 0016-8025, E-ISSN 1365-2478, Vol. 25, nr 2, s. 251-268Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seismic reflection methods are being developed at the University of Manitoba to aid in determining fine crustal structures in the Precambrian of Manitoba and northwestern Ontario. Present-day environmental concern as well as mineshaft conditions necessitate the detonation of several smaller charges repeated, say, I times and followed by ''vertical'' stacking. To obtain the familiar ..sqrt..I improvement in signal-to-noise (S : N) amplitude ratio applying the straight-sum (SS) method, one assumes, among other things, that both S : N ratio and signal variance are the same on all traces. Dropping these assumptions, as we must for our data, it becomes necessary to apply weighting coefficients to optimize the S : N ratio of the stacked trace. We still assume the signal shapes to be the same for repeated shots, so for the jth trace on the record of the ith shot we model the time series as: t/sub ij/ = a/sub i/(s/sub j/ + n/sub ij/); where a/sub i/ is a scaling factor. The proper weights w/sub i/ are then shown to be proportional to sigma/sub si//sigma/sup 2//sub ni/ where sigma/sup 2/ is variance, or to ..gamma../sub i//a/sub i/ where ..gamma../sub i/ is S : N power ratio. Applying the weighted-stack (WS) method gives S : N amplitude ratios which are, on average, 55% of the optimal ratios expected from WS theory compared with only 24% for the SS method. The 45% shortfall in WS performance is ascribed mainly to trace-alignment (or time-delay) errors. Varying noise levels on individual traces, slight dissimilarity of signal shape, and correlated noise may also contribute to a lesser extent (in decreasing order of significance). This WS method appears to strike a good practical balance between S : N improvement and processing efficiency.

  • 254.
    Bruckman, Viktor
    et al.
    Austrian Academy of Sciences, Section for Mathematics and Natural Sciences.
    Hangx, SuzanneDepartment of Earth Sciences, Utrecht University.Ask, MariaLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    European Geosciences Union General Assembly 2014, EGU Division Energy, Resources & the Environment (ERE)2014Samlingsverk (redaktörskap) (Refereegranskat)
  • 255. Bruggeman, C.
    et al.
    Maes, N.
    Christiansen, B. C.
    Stipp, S. L. S.
    Breynaert, E.
    Maes, A.
    Regenspurg, Simona
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi (flyttat 20130630).
    Malmström, Maria E.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Liu, X.
    Grambow, B.
    Schaefer, Th
    Redox-active phases and radionuclide equilibrium valence state in subsurface environments - New insights from 6th EC FP IP FUNMIG2012Ingår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 27, nr 2, s. 404-413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Within the 6th EC FP Integrated Project "Fundamental Processes of Radionuclide Migration'' (FUNMIG), progress has been made to improve knowledge about the phases and reaction mechanisms involved in complex reduction processes of radionuclide contaminants in natural subsurface environments. This review paper gives an overview of the achievements made by the research groups involved in this project, and puts the scope and results of the studies in a more global context. Firstly, both thermodynamic and experimental evidence show that green rust is present and reactive in subsurface groundwater with a composition that spans the Fe(II)/Fe(III) redox boundary. Green rust has been shown to reduce Np(V), Se(VI) and Se(IV), but the pathways for the redox processes and the reaction products that result are complicated, and change as a function of the reaction parameters. Secondly, considerable evidence has emerged that Se(IV) is reduced on Fe(II)-bearing minerals which are ubiquitous in subsurface environments. The stable Se valence state in the presence of FeS(2) has been shown to be Se(0). Also, natural dissolved humic substances that contain sufficient electron donating capacity are capable of interacting with, and possibly reducing, Se(IV) to lower valence states. Thirdly, the influence of HCO(3)(-) and organic ligands on the uptake and reduction of U(VI) on Fe(II)-bearing minerals was investigated. While it appeared that HCO(3)(-) decreased the extent of U(VI) uptake by the reducing surface, the fraction of reduced U(IV) in the solid phase increased with increasing HCO(3)(-) concentration. In contrast with the observations for HCO(3)(-), organic ligands decreased both the extent of U uptake, as well as the fraction of U(IV) found in the solid phase. The studies performed within FUNMIG show that investigating reduction-oxidation mechanisms require (1) a detailed control over reaction conditions (anoxic atmosphere, purification of solid phases, initial radionuclide speciation), (2) a rigorous follow-up of reaction products (both solution chemistry and spectroscopic methods), and (3) the consideration of slow kinetics in the setting up of an experiment. These requirements make the study and assessment of redox processes one of the most demanding scientific challenges for geochemists who are asked to make predictions for radionuclide transport behaviour in the environment.

  • 256.
    Bruschini, Enrico
    et al.
    Sapienza Università di Roma.
    Speziale, Sergio
    Geoforschungszentrum, Potsdam.
    Andreozzi, Giovanni
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Sapienza Università di Roma.
    Hålenius, Ulf
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    The elasticity of MgAl2O4-MnAl2O4 spinels by Brillouin scattering and an empirical approach for bulk modulus prediction2015Ingår i: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 100, s. 644-651Artikel i tidskrift (Refereegranskat)
  • 257.
    Brüchert, Volker
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Bonaglia, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Raymond, Caroline
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Sediment med nyckelroll i näringsväven2014Ingår i: HavsUtsikt, ISSN 1104-0513, Vol. 1, s. 20-21Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    I sedimenten sker processer som kan vara helt avgörande för näringsbalansen i havsvattnet. Omvandlingen av fosfor till olika former är relativt väl känd, medan detaljerna i kvävets kretslopp är betydligt mindre kända. Mer än hälften av den årliga tillförseln av kväve till Östersjön beräknas omsättas till kvävgas i sedimentet, vilket sedan går förlorat för de flesta marina organismer.

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    Sediment med nyckelroll
  • 258.
    Buckland, Philip I.
    et al.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Eriksson, Erik J.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Palm, Fredrik
    Umeå universitet, Humanistiska fakulteten, Humlab.
    SEAD - The Strategic Environmental Archaeology Database: Progress Report Spring 20142014Rapport (Övrigt vetenskapligt)
    Abstract [en]

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

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    SEAD - Progress Report Spring 2014
  • 259. Budd, D.A.
    et al.
    Troll, V.R.
    Deegan, F.M.
    Jolis, E.M.
    Smith, V.C.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Harris, C.
    Freda, C.
    Hilton, D.R.
    Halldorsson, S.A.
    Bindemann, I.N.
    Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 40624Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ18O values. Overall, Toba quartz crystals exhibit comparatively high δ18O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ18O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆core−rim = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ18O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ18O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

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  • 260.
    Budd, David A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Ist Nazl Geofis & Vulcanol, Rome, Italy.
    Deegan, Frances M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Swedish Museum Nat Hist, Dept Geosci, Stockholm, Sweden.
    Jolis, Ester
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Smith, Victoria
    Research Laboratory for Archaeology and the History of Art, University of Oxford, Oxford, UK.
    Whitehouse, Martin
    Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Harris, Chris
    Department of Geological Sciences, University of Cape Town, South Africa.
    Freda, Carmela
    Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy.
    Hilton, David
    Scripps Institution of Oceanography, University of California, San Diego, USA.
    Halldórsson, Sæmundur
    Scripps Institution of Oceanography, University of California, San Diego, USA; Univ Iceland, Inst Earth Sci, Reykjavik, Iceland.
    Bindeman, Ilya
    Department of Geological Sciences, University of Oregon, Oregon, USA.
    Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 40624Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ18O values. Overall, Toba quartz crystals exhibit comparatively high δ18O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ18O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆core−rim = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ18O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ18O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

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    fulltext
  • 261.
    Bukała, Michał
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Krakow, Poland.
    Klonowska, Iwona
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Barnes, Christopher
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Krakow, Poland.
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Krakow, Poland.
    Kośmińska, Karolina
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Krakow, Poland.
    Janák, Marian
    Slovak Acad Sci, Earth Sci Inst, Bratislava, Slovakia.
    Broman, Curt
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Luptáková, Jarmila
    Slovak Acad Sci, Earth Sci Inst, Banska Bystrica, Slovakia.
    UHP metamorphism recorded by phengite eclogite from the Caledonides of northern Sweden: P-T path and tectonic implications2018Ingår i: Journal of Metamorphic Geology, ISSN 0263-4929, E-ISSN 1525-1314, Vol. 36, nr 5, s. 547-566Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Seve Nappe Complex (SNC) of the Scandinavian Caledonides records a well‐documented history of high pressure (HP) and ultra‐high pressure (UHP) metamorphism. Eclogites of the SNC occur in two areas in Sweden, namely Jämtland and Norrbotten. The Jämtland eclogites and associated rocks are well‐studied and provide evidence for late Ordovician UHP metamorphism, whereas the Norrbotten eclogites, formed during the late Cambrian (Furongian)/Early Ordovician, have not been studied in such detail, especially in terms of the P–T conditions of their formation. Within the studied eclogite, clinopyroxene contains a high‐Na core and two rims: inner, medium‐Na and outer, low‐Na. Garnet consists of a high‐Ca euhedral core, low‐Ca inner rim and medium‐Ca outer rim. A similar pattern occurs within phengite, where high‐Si cores are enveloped by medium and low‐Si rims. The compositions of the mineral cores, inner rims and outer rims reflect three stages in the metamorphic evolution of the eclogite. Applied Quartz‐in‐Garnet geobarometry, coupled with Zr‐in‐rutile geothermometry reveal that garnet nucleation (E0 stage) took place at 1.5–1.6 GPa and 620–660°C. The eclogite peak‐pressure assemblage developed during the E1 stage, it consists of garnet+omphacite+phengite+rutile+coesite? and yields P–T conditions of 2.8–3.1 GPa and 660–780°C as constrained by conventional geothermobarometry and thermodynamic modelling in the NCKFMMnASHT system. Later, lower‐pressure stages E2 and E3 record conditions of 2.2–2.8 GPa, 680–780°C and 2.1 GPa, 735°C, respectively. The prograde metamorphic evolution of the eclogite is inferred from inclusions of epidote, amphibole and clinopyroxene within garnet. The presence of amphibole–quartz–plagioclase symplectites, secondary epidote/zoisite and titanite replacing rutile record the later retrograde changes taking place at <1.5 GPa (referred as E4 stage). The obtained P–T conditions indicate that the Norrbotten eclogites underwent a metamorphic evolution characterized by a clockwise P–T path with peak metamorphism reaching up to coesite stability field within a relatively cold subduction regime (7.8°C/km). The obtained results provide the first evidence for UHP metamorphism in the SNC above the Arctic Circle and document cold subduction regime and multistage exhumation of the deeply subducted Baltican margin at early stage of the Caledonian Orogeny.

  • 262.
    Bundschuh, Jochen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Sracek, O.
    Hydrogeochemistry principles for geochemical modeling2011Ingår i: Geochemical Modeling of Groundwater, Vadose and Geothermal Systems, CRC Press , 2011, s. 3-26Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    A wide diversity of physical and chemical processes control the distribution of species in waters in the vadose zone above the water table, and in the saturated zone below. The mineralogical composition of rocks or sediments, chemical reactions between solid, aqueous and gas phases, and oxidation/reduction (redox) processes are principal factors that influence the chemical composition of vadose-zone, ground-and surface waters, and the concentrations and mobilities of individual species. 

  • 263. Burman, Jan-Ola
    Element transports in suspended and dissolved phases in the Kalix River1983Ingår i: Environmental biogeochemistry: proceedings of the 5th International symposium on environmental biogeochemistry (ISEB) arranged in Stockholm 1-5 June, 1981 / [ed] Rolf O. Hallberg, Stockholm: Forskningsrådsnämndens förlagstjänst , 1983, s. 99-113Konferensbidrag (Refereegranskat)
    Abstract [en]

    River water samples were collected ten times during a 24-month period at 16 stations in the Raane, Toere, Kalix and Torne rivers in northern Sweden. Silicon, Al, Mn, Fe, Ca, Mg, Na, Ba and Sr were measured in the aqueous phase and in addition Cu, Ni, Zr, Cr, Zn and V were determined in the suspended fraction. This report is restricted to six stations in the Kalix River. Silicon, Ca, Mg, Na, Sr and Ba are predominantly transported in dissolved phase, whereas most of the Fe and Al are in the suspended fraction. Mn is almost equally distributed between the phases. The annual run off from the Kalix River to the Bothnian Bay shows very high concentrations of Fe and Mn in the suspended matter. Furthermore, this fraction consists of at least four independent phases. Fe and Mn are not correlated and Mn might be of biogeochemical origin

  • 264. Burman, Jan-Ola
    Geochemical studies of north Swedish rivers using inductively coupled plasma optical emission spectroscopy for multielement determinations1982Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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    FULLTEXT01
  • 265. Burman, Jan-Ola
    et al.
    Boström, Kurt
    Luleå tekniska universitet.
    Comparison of different plasma excitation and calibration methods in the analysis of geological materials by optical emission spectrometry1979Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 51, nr 4, s. 516-520Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A comparative study has been made of different dissolution and calibration methods for analyses by optical emission spectrometry (OES) utilizing inductively coupled plasma (ICP) and capacitively coupled microwave plasma (MWP) as excitation sources. The test substances were geological standard rocks, in which SlO2, Al2O3, TiO2, Fe2O3, MnO, MgO CaO, Na2O, Ba, and some traces were determined. The results show that analyses by MWP-OES are severely disturbed by matrix effects; only in the presence of large quantities of ionization buffers e.g., [Sr(NO3)2] can MWP-OES yield rock analyses of very good quality. No buffers are needed for analyses by ICP-OES, for which the matrix effects are remarkably low. ICP-OES may suffer from annoying nebulizer disturbances when concentrated solutions are used but, with properly diluted solutions, all major and many trace elements can routinely be analyzed in 50-mg rock samples. MWP-OES on the other hand is poorly suited for trace element determinationsA comparative study has been made of different dissolution and calibration methods for analyses by optical emission spectrometry (OES) utilizing inductively coupled plasma (ICP) and capacitively coupled microwave plasma (MWP) as excitation sources. The test substances were geological standard rocks, in which SlO2, Al2O3, TiO2, Fe2O3, MnO, MgO CaO, Na2O, Ba, and some traces were determined. The results show that analyses by MWP-OES are severely disturbed by matrix effects; only in the presence of large quantities of ionization buffers e.g., [Sr(NO3)2] can MWP-OES yield rock analyses of very good quality. No buffers are needed for analyses by ICP-OES, for which the matrix effects are remarkably low. ICP-OES may suffer from annoying nebulizer disturbances when concentrated solutions are used but, with properly diluted solutions, all major and many trace elements can routinely be analyzed in 50-mg rock samples. MWP-OES on the other hand is poorly suited for trace element determinations. © 1979 American Chemical Society.

  • 266.
    Burman, Jan-Ola
    et al.
    Luleå tekniska universitet.
    Boström, Kurt
    Use of ICP-AES in marine geochemistry1982Ingår i: ICP Information Newsletter, Vol. 7, nr 10, s. 493-Artikel i tidskrift (Övrigt vetenskapligt)
  • 267. Burman, Jan-Ola
    et al.
    Johansson, B.
    Morefält, B.
    Närfeldt, K.-H.
    Olsson, L.
    Automated inductively-coupled plasma optical emission spectrometry based on a sequential reading monochromator1981Ingår i: Analytica Chimica Acta : Computer Techniques and Optimization, ISSN 0378-4304, Vol. 133, nr 3, s. 379-392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An automated computer-controlled sequential reading monochromator system for optical emission spectrometry with an inductively-coupled plasma as source is described. The system selects the set of emission lines which are best suited for each type of sample. Multi-element analysis of major and trace elements is done automatically, including sample changing, calibration, background correction and presentation of results

  • 268. Burman, Jan-Ola
    et al.
    Ponter, Christer
    Luleå tekniska universitet.
    Boströn, Kurt
    Luleå tekniska universitet.
    Metaborate digestion procedure for inductively coupled plasma-optical emission spectrometry1978Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 50, nr 4, s. 679-680Artikel i tidskrift (Refereegranskat)
  • 269.
    Byggeth, Martin
    Luleå tekniska universitet.
    Biologiska indikatorsystem och indikatororganismer: en litteraturstudie med inriktning mot Bottenvikens havsområde1992Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Biologiska indikatorer, i form av indikatorsystem alternativt enskilda indikatororganismer, ger kvalitativ information om ett ekosystems historia, aktuella status och utvecklingstrender. Biologiska indikatorsystem baserade på interaktioner mellan arter i ekosystem ger kvalitativt unika resultat och bör ingå i effektiva miljöövervakningssystem. Interaktionerna i biologiska indikatorsystem kan vara svåra att utvärdera, vilket leder till att enskilda indikatororganismer används som indikatorer. Dock kan denna information aldrig ersätta den som indikatorsystemen ger. Krav på en enskild indikatororganism, är att den skall vara abundant och stationär inom undersökningsområdet, samt vara lätt att fånga eller att samla in. Organismen bör ackumulera föroreningar utan omfattande letalitet, kunna uppvisa föroreningsgradienter inom undersökningsområdet, samt vara av rimlig storlek för organ- eller vävnadsanalyser. Organismen skall leva tillräckligt länge för att möjliggöra åldersrelaterade studier, samt klara av att leva i laboratoriemiljö utan att predera den egna arten. Den bör även ha ett kontrollerbart reproduktionsmönster. Slutligen skall indikatororganismen ha en väl känd fysiologi och ekologi. För miljöövervakning inom Bottenvikens havsområde är följande arter intressanta för utveckling av biologiska indikatorsystem: Nitocra spinipes L., copepod; Saduria (Mesidothea) entomon L., skorv; Corophium volutator L., slammärla; Pontoporeia (Monoporeia) affinis LINDSTRÖM, vitmärla; Theodoxus fluviatilis L., algsnäcka; Lymnaea peregra L., dammsnäcka; Anodonta cygnea L., dammussla; Pisidium amnicum L., ärtmussla; Phoxinus phoxinus L., elritsa; Alburnus alburnus L., löja; Pomatoschistus (Gobius) minutus PALLAS, sandstubb och Myoxocephalus (Cottus) quadricornis L. hornsimpa.

  • 270.
    Bäckström, Mattias
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Environmental impact from an alum shale deposit, Kvarntorp, Sweden: Present and future scenarios2010Ingår i: Mine water & innovative thinking: proceedings 2010 / [ed] Wolkersdorfer, C. and Freund, A., Nova Scotia, Canada: Cape Breton University Press , 2010, s. 551-554Konferensbidrag (Refereegranskat)
    Abstract [en]

    During the second World War it was decided to produce oil through pyrolysis of alum shalegiving rise to waste products (coke and ash). Waste was deposited in the open pits and in a waste deposit.Due to the high remaining energy in the waste materials the waste deposit still today has significantlyelevated temperatures (above 500 °c). remaining pyrite in the waste material has also led to ArDwith elevated trace metal concentrations. the waste deposit is no great environmental problemtoday but as soon as the waste pile cools off both the volumes of drainage and concentrations oftrace metals will increase dramatically

  • 271.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Domeij, Joel
    Sartz, Lotta
    Örebro universitet, Institutionen för naturvetenskap och teknik. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Flooding of oxidized waste rock amended with alkaline by-products2010Ingår i: 34th British Columbia Mine Reclamation & 35th CLRA/ACRSD National Conference, 2010, s. 10 pages-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Leaching of trace elements (Cd, Cu, Pb and Zn) from oxidized waste rock amended with different alkaline by-products was studied during flooding. It has been argued that water covers for oxidized waste would significantly increase leaching through reductive dissolution of the pre-formed hydrous ferric oxides and the associated trace elements. After approximately three weeks pH in the reference had reached 2.5 and 3.3 in the pore and overlying water, respectively. This can be compared with pH from 6.1 (water works granules) to above 10 (lime kiln dust) in the amended systems. It is clear that the carbonate dominated alkaline by-products have lower pH than the oxide/hydroxide based by-products. However, the systems amended with carbonate based by-products have significantly higher alkalinity. Cadmium, Cu, Pb and Zn concentrations within the waste decreased with at least 99% compared to the reference. In most systems the surface waters can even be used as drinking water. Cadmium, copper and zinc concentrations are clearly related to pH with decreasing concentrations with increasing pH. Lead concentrations, on the other hand, decrease to pH 8, where the concentrations start to increase slightly again due to the formation of soluble Pb(OH)₃⁻ and Pb(OH)₄²⁻ species. The results indicate that flooding of oxidized waste rock amended with alkaline by-products can be used as a successful remediation technique.

  • 272.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Sartz, Lotta
    Örebro universitet, Institutionen för naturvetenskap och teknik. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Stabilization of acid generating waste rock with fly ash: Immobilization of arsenic under alkaline conditions2010Ingår i: Mine water & innovative thinking: proceedings 2010 / [ed] Wolkersdorfer, C. and Freund, A., ovaScotia, Canada: Cape Breton University Press , 2010, s. 555-558Konferensbidrag (Refereegranskat)
    Abstract [en]

    A fly ash was used to increase pH and decrease arsenic leaching from an acidic mine waste.Both the amended system as well as the control system was leached with ultra pure water. pH in thecontrol increased from 1.7 to 2.7 at the end of the experiment while the pH in the amended systemdecreased from 12.6 to 11.5. compared to the control the initial concentrations of arsenic decreasedwith almost three orders of magnitude in the amended systems. A combination of co precipita-tion with iron and calcium arsenate precipitation were identified as the major arsenic immobi-lization mechanisms.

  • 273.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Sartz, Lotta
    Örebro universitet, Institutionen för naturvetenskap och teknik. Bergskraft Bergslagen AB, Kumla, Sweden.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kumla, Sweden.
    Mining Waste as an Exploration Tool and Secondary Resource2017Ingår i: Mine Water & Circular Economy / [ed] Wolkersdorfer, C., Sartz, L., Sillanpää, M. and Häkkinen, A, Lappeenranta, Finland: Lappeenranta University of Technology , 2017, Vol. II, s. 964-971Konferensbidrag (Refereegranskat)
    Abstract [en]

    There is today no overall information about how much mining waste there is in Sweden and what it contains. This project focused on samples from waste rock, tailings and slag from the historical mining region Bergslagen, Sweden. Modern dissolution and analytical methods were used in order to determine approximately 50 elements in the samples. Modern analytical data for the historical mining waste is useful as an exploration tool and can provide information about remaining or new resources underground. Results show that there is a potential for recovery of critical elements from mining waste as well as dealing with environmental problems.

    Ladda ner fulltext (pdf)
    Mining Waste as an Exploration Tool and Secondary Resource
  • 274.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Suggestion for a protocol for detailed investigation of historical mine sites2012Ingår i: 9th International Conference on Acid Rock Drainage (ICARD 2012) / [ed] Price, W.A., Hogan, C. and Tremblay, G., Red Hook, NY: Curran Associates, Inc., 2012, s. 1340-1350Konferensbidrag (Refereegranskat)
    Abstract [en]

    A protocol for detailed investigation of mine sites is suggested. Results from the investigation are important when planning mine site reclamation. Initially, the mine site is divided into several sub sites according to topography. For general appearance the following parameters were developed and estimated directly in the field for every sub site:

    (1) shape, (2) historical land use, (3) amount of waste rock, (4) weathering, (5) waste rock size, (6) carbonates and silicates, (7) vegetation cover, (8) low and high species, (9) moss and grass/herbs, (10) broad-leaf and coniferous, (11) spruce and pine, (12) birch and aspen, and (13) blueberries and lingonberries. Every parameter was designated a numerical value between 0 and 5. After sampling ocular mineral/rock classification was performed on composite samples from every sub site and the following major components were determined: (14) silicate, (15) mica, (16) granite/pegmatite, (17) carbonates, (18) iron oxide ore and (19) sulphide ore. In addition the relative distribution between the different sulphide minerals was also determined: (20) chalcopyrite vs sphalerite; (21) galena vs sphalerite; (22) chalcopyrite vs galena and (23) pyrite vs pyrrhotite.

    Results from a historical mine site in Kopparberg, Sweden, are used to illustrate the methodology

  • 275. Cabral, R.A.
    et al.
    Jackson, M.G.
    Koga, K.T.
    Rose-Koga, E.F.
    Hauri, E.H.
    Whitehouse, Martin J.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Price, A.A:
    Day, J.M.D.
    Shimizu, N.
    Kelley, K.A.
    Volatile cycling of H2O, CO2, F, and Cl in the HIMU mantle: A new window provided by melt inclusions from oceanic hotspot lavas at Mangaia, Cook Islands.2014Ingår i: Geochemistry, Geophysics, Geosystems, ISSN 1525-2027, Vol. 15, s. 4445-4467Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mangaia hosts the most radiogenic Pb-isotopic compositions observed in ocean island basalts and represents the HIMU (high µ = 238U/204Pb) mantle end-member, thought to result from recycled oceanic crust. Complete geochemical characterization of the HIMU mantle end-member has been inhibited due to a lack of deep submarine glass samples from HIMU localities. We homogenized olivine-hosted melt inclusions separated from Mangaia lavas and the resulting glassy inclusions made possible the first volatile abundances to be obtained from the HIMU mantle end-member. We also report major and trace element abundances and Pb-isotopic ratios on the inclusions, which have HIMU isotopic fingerprints. We evaluate the samples for processes that could modify the volatile and trace element abundances postmantle melting, including diffusive Fe and H2O loss, degassing, and assimilation. H2O/Ce ratios vary from 119 to 245 in the most pristine Mangaia inclusions; excluding an inclusion that shows evidence for assimilation, the primary magmatic H2O/Ce ratios vary up to ∼200, and are consistent with significant dehydration of oceanic crust during subduction and long-term storage in the mantle. CO2 concentrations range up to 2346 ppm CO2 in the inclusions. Relatively high CO2 in the inclusions, combined with previous observations of carbonate blebs in other Mangaia melt inclusions, highlight the importance of CO2 for the generation of the HIMU mantle. F/Nd ratios in the inclusions (30 ± 9; 2σ standard deviation) are higher than the canonical ratio observed in oceanic lavas, and Cl/K ratios (0.079 ± 0.028) fall in the range of pristine mantle (0.02–0.08).

  • 276.
    Cabri, Louis J.
    et al.
    Cabri Consulting Inc, Ottawa, Canada.
    Aiglsperger, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    A review of hexaferrum based on new mineralogical data2018Ingår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 82, nr 3, s. 531-538Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hexaferrum, defined as an hcp Fe mineral containing varying amounts of Ru, Os, or Ir(Mochalov et al. 1998) was re-examined in the light of new analyses of similar alloys from the Loma Peguera and Loma Larga chromitites, in the central part of Loma Caribe peridotite, Cordillera Central of the Dominican Republic, together with a review of the phase chemistry inthe Fe-Ni-Ir and Fe-Ru-Ir systems. We conclude that the hcp (Fe,Ir) mineral corresponds to theε-phase of Raub et al. (1964) and should be differentiated from hexaferrum [(Fe,Os) and(Fe,Ru)] because it is separated by one to two miscibility gaps and therefore is not a continuous solid solution with Fe.

  • 277. Camino-Serrano, Marta
    et al.
    Guenet, Bertrand
    Luyssaert, Sebastiaan
    Ciais, Philippe
    Bastrikov, Vladislav
    De Vos, Bruno
    Gielen, Bert
    Gleixner, Gerd
    Jornet-Puig, Albert
    Kaiser, Klaus
    Kothawala, Dolly
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Lauerwald, Ronny
    Peñuelas, Josep
    Schrumpf, Marion
    Vicca, Sara
    Vuichard, Nicolas
    Walmsley, David
    Janssens, Ivan A.
    ORCHIDEE-SOM: Modeling soil organic carbon (SOC) and dissolved organic carbon (DOC) dynamics along vertical soil profiles in Europe2018Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 11, nr 3, s. 937-957Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Current Land Surface Models (LSMs) typically represent soils in a very simplistic way, assuming soil organic carbon (SOC) as a bulk, thus impeding a correct representation of deep soil carbon dynamics. Moreover, LSMs generally neglect the production and export of dissolved organic carbon (DOC) from soils to rivers, leading to overestimations of the potential carbon sequestration on land. These common oversimplified processing of SOC in LSMs is partly responsible for the large uncertainty in the predictions of the soil carbon response to climate change. In this study, we present a new soil carbon module called ORCHIDEE-SOM, embedded within the land surface model ORCHIDEE, which is able to reproduce the DOC and SOC dynamics in a vertically discretized soil to two meters. The model includes processes of biological production and consumption of SOC and DOC, DOC adsorption on- and desorption from soil minerals, diffusion of SOC and DOC and DOC transport with water through and out of the soils to rivers. We evaluated ORCHIDEE-SOM against observations of DOC concentrations and SOC stocks from four European sites with different vegetation covers: a coniferous forest, a deciduous forest, a grassland and a cropland. The model was able to reproduce the SOC stocks along their vertical profiles at the four sites and the DOC concentrations within the range of measurements, with the exception of the DOC concentrations in the upper soil horizon at the coniferous forest. However, the model was not able to fully capture the temporal dynamics of DOC concentrations. Further model improvements should focus on a plant- and depth- dependent parameterization of the new input model parameters, such as the decomposition times of DOC and the microbial carbon use efficiency. We suggest that this new soil module, when parameterized for global simulations, will improve the representation of the global carbon cycle in LSMs, thus helping to constrain the predictions of the future SOC response to global warming.

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    fulltext
  • 278.
    Canfield, Donald E.
    et al.
    University of Southern Denmark.
    Ngombi Pemba, Lauriss
    Hammarlund, Emma
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Chaussidon, Marc
    Gauthier Lafaye, François
    Meunier, Alain
    Riboulleau, Armelle
    Rollion Bard, Claire
    Rouxel, Olivier
    Asael, Dan
    Wickmann, Anne Catherine
    El Albani, Abderrazak
    Oxygen dynamics in the aftermath of the Great Oxidation of the Earth’s atmosphere.2013Ingår i: Proceedings of the National Academy of Sciences, ISSN 0027-8424, Vol. 110, nr 42, s. 16736-16741Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The oxygen content of Earth’s atmosphere has varied greatly through time, progressing from exceptionally low levels before about 2.3 billion years ago, to much higher levels afterward. In the absence of better information, we usually view the progress in Earth’s oxygenation as a series of steps followed by periods of relative stasis. In contrast to this view, and as reported here, a dynamic evolution of Earth’s oxygenation is recorded in ancient sediments from the Republic of Gabon from between about 2,150 and 2,080 million years ago. The oldest sediments in this sequence were deposited in well-oxygenated deep waters whereas the youngest were deposited in euxinic waters, which were globally extensive. These fluctuations in oxygenation were likely driven by the comings and goings of the Lomagundi carbon isotope excursion, the longest–lived positive ?13C excursion in Earth history, generating a huge oxygen source to the atmosphere. As the Lomagundi event waned, the oxygen source became a net oxygen sink as Lomagundi organic matter became oxidized, driving oxygen to low levels; this state may have persisted for 200 million years.

    Ladda ner fulltext (pdf)
    Canfield_etal_2013_Oxygen
  • 279. Carlsson, Eric
    et al.
    Holmström, Henning
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Water-solid interactions in tailings remediated by covering with till, Kristineberg Mine, northern Sweden1999Ingår i: Journal of Conference Abstracts, Vol. 4, nr 1, s. 511-Artikel i tidskrift (Övrigt vetenskapligt)
  • 280.
    Carlsson, Erik
    Luleå tekniska universitet.
    Geochemical effects of soil cover remediation on sulphide-rich tailings at the Kristineberg mine, northern Sweden2000Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Remediation of mine waste by the application of till cover is one of the more common methods used in Sweden to prevent oxidation of sulphide-rich minerals. Although the general conclusion from Swedish state-of-the-art field studies is that dry covers may be effective, they are expensive to construct. Further investigations are also needed to understand the processes occurring in till covered waste deposits. The Kristineberg mining area has been chosen as the main field site for the research program MiMi (Mitigation of the environmental impact of mining waste) funded by the Foundation for Strategic Environmental Research (MISTRA). MiMi focuses on finding new and improved methods to mitigate the environmental problems related to mining operations and disposal of mining waste. An extensive sampling programme was carried out in Kristineberg during 1998 and 1999. The Kristineberg mine is a Boliden mine, located within the Skellefte ore field. It is a Zn-Cu deposit developed in the 1940s and still in production. This thesis consists of three papers outlining the geochemical conditions prevailing in tailings Impoundment 1 at the Kristineberg mine, after remediation by applying till cover. The impoundment investigated was in use until the early 1950s and it was remediated in 1996. Two different remediation methods have been used; in the area with a shallow groundwater table 1.0 m of till was used to raise the groundwater table above the tailings. In other areas, with a deeper groundwater table, a sealing layer consisting of a 0.3 m thick layer of a compacted clayey till underlying a 1.5 m thick protective cover of unspecified till was used. Field studies include sampling of solid tailings, saturated tailings pore water as well as pore water from the vadose zone. Laboratory investigations consist of a five-step sequential extraction on solid tailings samples. Pre-remediation oxidation has resulted in a zonation of the tailings with an upper oxidised zone above unoxidised tailings. Just below the oxidation front, there is a secondary enrichment of especially Cu but also of other elements. Metals released by sulphide oxidation were thus secondarily enriched. Tailings remediated by the combination of a till cover and a raised groundwater table, resulted in a remobilisation of metals around and a few metres below the former oxidation front. Although the concentrations of several elements still are high in the pore water, they are lower than before the remediation. The general conclusion is that the remediation has succeeded in preventing further oxidation in this part of the impoundment. Sequential extractions performed on selected samples from the drilling of the impoundment show that most of the remaining sulphide-associated trace elements in the oxidised zone still belong to the sulphide fraction. At the level of the peaks of metal concentrations in the pore water (and the solid secondary enrichment) substantial concentrations of the trace elements Cd, Co, Cu, Ni, and Zn is present in the adsorbed/exchangeable/carbonate fraction. Other trace elements are retained with other secondary formations such as amorphous or crystalline iron oxyhydroxides e.g., As, Ba, and Pb. Especially the adsorbed/exchangeable/carbonate fraction is easily dissolved and the raised groundwater table remobilise these trace elements into the pore water, as could be seen from the pore water extractions. In Impoundment 1, where the sealing layer was applied, sampling of the infiltrating water was performed by tension lysimeters. Tension lysimeters were installed in the protective till cover, in the oxidised tailings, in the uppermost unoxidised tailings and at an intermediate depth. The groundwater at the same location was also sampled. The tension lysimeters in the till protective cover contained relatively low concentrations of most elements. Elements such as Al, Cd, Co, Cu, Fe, Mn, Ni, S, Si, and Zn had the highest concentrations in the second tension lysimeter in the tailings. Between the second and the third tension lysimeters the concentration of most elements decreased. The increase between the first and the second tension lysimeters can be explained by remobilisation of secondarily retained oxidation products. The decrease between the second and the third tension lysimeters is interpreted as co-precipitation with different iron oxyhydroxides as well as adsorption onto secondarily formed minerals and primary mineral surfaces. Between the deepest tension lysimeter and the groundwater table, the element concentrations decrease further. Most of the pre-remediation oxidation products that are secondarily retained below the oxidation front and are released by the small amount of infiltrating water, is tertiarily retained during continued downward transport. Thus, if the depth to the groundwater table is large enough, the metals released by infiltrating water do not reach it.

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    FULLTEXT01
  • 281.
    Carlsson, Erik
    Luleå tekniska universitet.
    Sulphide-rich tailings remediated by soil cover: evaluation of cover efficiency and tailings geochemistry, Kristineberg, northern Sweden2002Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The efficiency of soil cover as a method of remediation of sulphide-rich tailings has been studied at an impoundment at the Kristineberg mine, Northern Sweden. Two variations of soil cover were used in the remediation. The major part of the impoundment was covered with a 1.0 m layer of till where the groundwater table was shallow. In combination with the removal of the water dividing ditches surrounding the impoundment, saturation of the tailings as well as the till cover was achieved. In areas with a deeper groundwater it was not possible to saturate the tailings by means of this method. Instead, a sealing layer consisting of a 0.3 m compacted clayey till, acting as an oxygen diffusion barrier, situated underneath a 1.5 m protective cover was used. Field studies at the impoundment cover pore-water extraction and solid-sample collection at five locations. Solid tailings were subject to sequential extractions in the laboratory. Open groundwater pipes for measuring groundwater levels as well as BAT® groundwater pipes for geochemical sampling of the groundwater were installed over the entire impoundment. At a location in the area with the sealing layer, tension lysimeters were installed in a profile in the vadose zone down to the unoxidised tailings. Nearby, one oxygen diffusion lysimeter and one water infiltration lysimeter were installed below 1.5, 1.0, and 0.3 m of protective till cover, respectively. The sealing layer has been investigated in the laboratory with respect to its susceptibility to the effects of freezing and thawing. The solid samples from the tailings revealed that in some areas, the sulphide oxidation prior to the remediation had been intense. In other areas, with a shallower pre-remediation groundwater table, the oxidation seemed to have ceased upon reaching it. In the area with water- saturated tailings increased pore water concentrations around and below the oxidation zone were visible, due to release of secondarily retained elements. Elements with peaks at this level were As, Cd, Co, Cr, Cu, Mo, Ni, Pb, and Zn. However, compared with pre-remediation data the concentrations are generally lowered, indicating that sulphide oxidation has slowed down. Sequential extraction of the solid tailings samples showed that a large part of the elements below the oxidation front, in the secondary enrichment layer, are relatively mobile and are released within the adsorbed, or the amorphous iron (oxy)hydroxide fractions. This was the case for elements such as Fe, As, Ba, Cd, Co, Cr, Cu, Ni, and Zn. The continuous measurements performed in the groundwater pipes show that elements released by raising the groundwater table are transported out of the impoundment, and that the overall water quality is constantly improving due to the inflow of uncontaminated groundwater from the adjacent hill slope. A model for the water transport has been developed and prediction of the future behaviour of the impoundment is proposed. The tension lysimeter measurements show that infiltrating water and diffusing oxygen cause remobilisation of metals around the oxidation front. However, most of these metals are retained again prior to reaching the groundwater table. The mass flow caused by this mobilisation is very small compared to that of the laterally flowing groundwater. Mobilised elements are Fe, S, Si, Al, Cd, Co, Hg, Mg, Mn, Mo, Ni, Pb, and Zn. The freeze/thaw laboratory experiments stress that the compaction degree is very important for achieving a hydraulic conductivity low enough for the requirements of a sealing layer. If a high enough compaction degree is obtained, the corresponding hydraulic conductivity is very low, approximately 5x10-10 m/s with the clayey till used at the study site. The freeze/thaw experiments also revealed that when properly compacted the clayey till is sensitive to frost penetration, leading to an increase of hydraulic conductivity, up to ~10-8 m/s. Oxygen diffusion measurements indicate that the effective diffusion through the sealing layer is low for all three different protective till-cover thicknesses, and so is the water infiltration. However, during the field measurements, no frost penetration into the sealing layer was monitored.

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    FULLTEXT01
  • 282.
    Carlsson, Erik
    et al.
    Luleå University of Technology.
    Thunberg, Jonas
    Luleå University of Technology.
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Holmström, Henning
    Envipro Miljöteknik AB, Linköping.
    Sequential extraction of sulfide-rich tailings remediated by the application of till cover, Kristineberg mine, northern Sweden2002Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 299, nr 1-3, s. 207-226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A sequential extraction has been carried out on sulfide-rich mine tailings. The purpose was to investigate how elements released by oxidation are secondarily retained in the tailings and the possible consequences of the remediation. After investigating the solid tailings, seven samples were chosen for sequential extractions. Two samples were oxidised, situated just above the oxidation front; two samples from just below the former oxidation front with increased concentrations of several elements; two unoxidised samples were from an intermediate depth, and the deepest sample was from the tailings-peat boundary at the bottom of the impoundment. Five phases were extracted: adsorbed/exchangeable/carbonate; labile organics; amorphous Fe-oxyhydroxides/Mn-oxides; crystalline Fe-oxides; and organics/sulfides. The addition from dried porewater to the extracted fractions has been calculated and considered as minor. In the oxidised tailings, the sulfide fraction still dominates for elements such as Fe, S, Cd, Co, Cu, Hg and Zn, although the concentrations are low compared to the unoxidised tailings. Generally, the second most important fraction is the adsorbed/exchangeable/carbonate fraction. Below the oxidation front, the sulfide content of the tailings sharply increases. In the secondary enrichment zone, the total element concentrations increase compared with the deeper unoxidised samples, mainly due to secondary retention. For some elements, secondary retention is greater than the total amount extracted for the deeper unoxidised samples. In the secondary enrichment zone the adsorbed/exchangeable/carbonate fraction represents approximately 20 wt.% or more for Cd, Co, Mn, Ni and Zn. The amorphous iron oxyhydroxide or the crystalline iron oxide fractions are less important at this level, although for As, Ba and Cu the amorphous iron oxyhydroxide fraction represents up to 20 wt.. At the lower border of the enrichment zone, the total concentration for most metals is lower, but the importance of the adsorbed/exchangeable/carbonate fraction is further enhanced for Cd, Cu, Ni and Zn. These elements have 35-60 wt.% of the total amount from this fraction. For As, Cd, Cu, Ni and Pb, the secondary fractions extracted (extractions A-D) represent between 60 and 80 wt.% of the total content. At greater depth in the impoundment the relative importance of the adsorbed/exchangeable/carbonate fraction decreases, whilst the importance of amorphous iron oxyhydroxide and crystalline iron oxide fractions increases. The adsorbed/exchangeable/carbonate fraction is the most easily remobilised fraction. A raised groundwater table previously situated below the enrichment zone may result in the release of secondarily retained metals.

  • 283.
    Carlsson, Erik
    et al.
    Luleå tekniska universitet.
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Holmström, Henning
    Envipro Miljöteknik AB, Linköping.
    Geochemistry of the infiltrating water in the vadose zone of a remediated tailings impoundment, Kristineberg, northern Sweden2003Ingår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 18, nr 5, s. 659-674Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    At the remediated tailings Impoundment 1 at Kristineberg, Northern Sweden, installations of tension lysimeters were performed in the protective cover (10, 50, and 100 cm), in the oxidised tailings (150 cm), in the unoxidised secondarily enriched tailings (200 cm) and in the unoxidised tailings (260 cm). The lysimeters in the till protective cover contained relatively low concentrations of most elements. After infiltration through the sealing layer, consisting of 0.3 m compacted clayey till, pH decreased and conductivity, together with the concentrations of several major and trace elements, increased significantly. In the lysimeters installed in the tailings at depths of 150 and 200 cm average pH decreased to 3.4 at 150 cm and 3.2 at 200 and average conductivity increased to 2.9 mS/cm. Elements such as Al, Cd, Co, Fe, Mn, Mo, Ni,Pb, S, Si and Zn had the highest concentrations in the lysimeter at 200 cm depth. Examples of concentration averages for this lysimeter are Cd 600 μg/L, Fe 1500 mg/L, Mn 11 mg/L, Ni 1.06 μg/L, S 1800 mg/L, and Zn 190 mg/L. Between the depths of 200 and 260 cm the concentration of most elements decreased. The increase between the lysimeters at the depths of 150 and 200 cm can be explained by remobilization of secondarily retained oxidation products as well as from the continued oxidation. The decrease between the second and the third lysimeters is interpreted as co-precipitation with different Fe oxyhydroxides as well as adsorption onto secondarily formed minerals and primary mineral surfaces. Calculations of saturation indices indicate that several different hydroxides might precipitate at this level. This retainment takes place mainly due to the increase in pH. The pH increases from 3.2 up to 4-4.4 in this depth interval. Between the deepest lysimeter and the groundwater table, the element concentrations probably decrease even further. pH increases to 5-6.5 in the groundwater. Most of the pre-remediation oxidation products that are secondarily retained above or below the oxidation front and are released by the small amount of infiltrating water together with the present oxidation products are retained again during continued transport downwards. If the depth to the groundwater table is large enough, most of the metals released by the infiltrating water and the diffusing O2 do not reach the groundwater.

  • 284.
    Carranza, Giovanni
    Luleå tekniska universitet.
    Geological setting and geochemistry of epithermal gold deposits in the Libertad and the Limon Areas, Nicaragua1991Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 285.
    Cassidy, Mike
    et al.
    Institute of Geosciences, University of Mainz, D-55122 Mainz, Germany.
    Castro, Jonathan
    Institute of Geosciences, University of Mainz, D-55122 Mainz, Germany .
    Helo, Christoph
    Institute of Geosciences, University of Mainz, D-55122 Mainz, Germany .
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Deegan, Frances M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Muir, Duncan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Neave, David
    Institute of Mineralogy, Leibniz University of Hannover, 30167 Hannover, Germany.
    Mueller, Sebastian
    Institute of Geosciences, University of Mainz, D-55122 Mainz, Germany .
    Volatile dilution during magma injections and implications for volcano explosivity2016Ingår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 44, nr 12, s. 1027-1030Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Magma reservoirs underneath volcanoes grow through episodic emplacement of magma batches. These pulsed magma injections can substantially alter the physical state of the resident magma by changing its temperature, pressure, composition, and volatile content. Here we examine plagioclase phenocrysts in pumice from the 2014 Plinian eruption of Kelud (Indonesia) that record the progressive capture of small melt inclusions within concentric growth zones during crystallization inside a magma reservoir. High-spatial-resolution Raman spectroscopic measurements reveal the concentration of dissolved H2O within the melt inclusions, and provide insights into melt-volatile behavior at the single crystal scale. H2O contents within melt inclusions range from ∼0.45 to 2.27 wt% and do not correlate with melt inclusion size or distance from the crystal rim, suggesting that minimal H2O was lost via diffusion. Instead, inclusion H2O contents vary systematically with anorthite content of the host plagioclase (R2 = 0.51), whereby high anorthite content zones are associated with low H2O contents and vice versa. This relationship suggests that injections of hot and H2O-poor magma can increase the reservoir temperature, leading to the dilution of melt H2O contents. In addition to recording hot and H2O-poor conditions after these injections, plagioclase crystals also record relatively cold and H2O-rich conditions such as prior to the explosive 2014 eruption. In this case, the elevated H2O content and increased viscosity may have contributed to the high explosivity of the eruption. The point at which an eruption occurs within such repeating hot and cool cycles may therefore have important implications for explaining alternating eruptive styles.

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  • 286. Cathalot, C.
    et al.
    Rabouille, C.
    Tisnerat-Laborde, N.
    Toussaint, F.
    Kerherve, P.
    Buscail, R.
    Loftis, K.
    Sun, M. -Y
    Tronczynski, J.
    Azoury, S.
    Lansard, B.
    Treignier, C.
    Pastor, L.
    Tesi, Tommaso
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    The fate of river organic carbon in coastal areas: A study in the Rhone River delta using multiple isotopic (delta C-13, Delta C-14) and organic tracers2013Ingår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 118, s. 33-55Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A significant fraction of the global carbon flux to the ocean occurs in River-dominated Ocean Margins (RiOMar) although large uncertainties remain in the cycle of organic matter (OM) in these systems. In particular, the OM sources and residence time have not been well clarified. Surface (0-1 cm) and sub-surface (3-4 cm) sediments and water column particles (bottom and intermediate depth) from the Rhone River delta system were collected in June 2005 and in April 2007 for a multi-proxy study. Lignin phenols, black carbon (BC), proto-kerogen/BC mixture, polycyclic aromatic hydrocarbons (PAHs), carbon stable isotope (delta C-13(OC)), and radiocarbon measurements (delta C-14(OC)) were carried out to characterize the source of sedimentary organic material and to address degradation and transport processes. The bulk OM in the prodelta sediment appears to have a predominantly modern terrigenous origin with a significant contribution of modern vascular C-3 plant detritus (Delta C-14(OC) = 27.9 parts per thousand, delta C-13(OC) = -27.4 parts per thousand). In contrast, the adjacent continental shelf, below the river plume, seems to be dominated by aged OM (Delta C-14(OC) = -400 parts per thousand, delta C-13(OC) = -24.2 parts per thousand), and shows no evidence of dilution and/or replacement by freshly produced marine carbon. Our data suggest an important contribution of black carbon (50% of OC) in the continental shelf sediments. Selective degradation processes occur along the main dispersal sediment system, promoting the loss of a modern terrestrial OM but also proto-kerogen-like OM. In addition, we hypothesize that during the transport across the shelf, a long term resuspension/deposition loop induces efficient long term degradation processes able to rework such refractory-like material until the OC is protected by the mineral matrix of particles.

  • 287.
    Chadwick, J.P.
    et al.
    Department of Petrology, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Waight, T.E.
    Department of Geography and Geology, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen, Denmark.
    van der Zwan, F.M.
    Department of Petrology, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
    Schwarzkopf, L.M.
    GeoDocCon, Unterpferdt 8, 95176 Konradsreuth, Germany.
    Petrology and geochemistry of igneous inclusions in recent Merapi deposits: a window into the sub-volcanic plumbing system2013Ingår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 165, nr 2, s. 259-282Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent basaltic-andesite lavas from Merapi volcano contain abundant and varied igneous inclusions suggesting a complex sub-volcanic magmatic system for Merapi volcano. In order to better understand the processes occurring beneath Merapi, we have studied this suite of inclusions by petrography, geochemistry and geobarometric calculations. The inclusions may be classified into four main suites: (1) highly crystalline basaltic-andesite inclusions, (2) co-magmatic enclaves, (3) plutonic crystalline inclusions and (4) amphibole megacrysts. Highly crystalline basaltic-andesite inclusions and co-magmatic enclaves typically display liquid–liquid relationships with their host rocks, indicating mixing and mingling of distinct magmas. Co-magmatic enclaves are basaltic in composition and occasionally display chilled margins, whereas highly crystalline basaltic-andesite inclusions usually lack chilling. Plutonic inclusions have variable grain sizes and occasionally possess crystal layering with a spectrum of compositions spanning from gabbro to diorite. Plagioclase, pyroxene and amphibole are the dominant phases present in both the inclusions and the host lavas. Mineral compositions of the inclusions largely overlap with compositions of minerals in recent and historic basaltic-andesites and the enclaves they contain, indicating a cognate or ‘antelithic’ nature for most of the plutonic inclusions. Many of the plutonic inclusions plot together with the host basaltic-andesites along fractional crystallisation trends from parental basalt to andesite compositions. Results for mineral geobarometry on the inclusions suggest a crystallisation history for the plutonic inclusions and the recent and historic Merapi magmas that spans the full depth of the crust, indicating a multi-chamber magma system with high amounts of semi-molten crystalline mush. There, crystallisation, crystal accumulation, magma mixing and mafic recharge take place. Comparison of the barometric results with whole rock Sr, Nd, and Pb isotope data for the inclusions suggests input of crustal material as magma ascends from depth, with a significant late addition of sedimentary material from the uppermost crust. The type of multi-chamber plumbing system envisaged contains large portions of crystal mush and provides ample opportunity to recycle the magmatic crystalline roots as well as interact with the surrounding host lithologies.

  • 288.
    Charette, M
    et al.
    Woods Hole Oceanographic Institution, USA.
    Lam, P.J.
    University of California Santa Cruz, USA.
    Lohan, M.C.
    University of Southhampton, UK.
    Kwon, E.Y.
    Seoul National University,Korea.
    Hatje, V
    Universidade Federal da Bahia, Brazil.
    Jeandel, C
    University of Toulouse, France.
    Shiller, A.M.
    University of Southern Mississippi, USA.
    Cutter, G.A.
    Old Dominion University, USA.
    Thomas, A
    University of Edinburgh, UK.
    Boyd, P.W.
    University of Tasmania, Australia.
    Homoky, W.B.
    University of Oxford, UK.
    Milne, A.
    Plymoth University, UK.
    Thomas, H.
    Dalhousie University, Canada.
    Andersson, P.S.
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Porcelli, D.
    University of Oxford,Uk.
    Tanaka, T
    University of Tokyo, Japan.
    Geibert, W
    Alfred Wegener Institute, Germany.
    Dehairs, F.
    Vrije Universiteit, Belgium.
    Garcia-Orellana, J.
    Universitat Autonoma de Barcelona, Spain.
    Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES2016Ingår i: Philosopical Transactions of the Royal Society A, ISSN 1364–503X, Vol. 374, nr 2081Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Continental shelves and shelf seas play a central role in the global carbon cycle. However,

    their importance with respect to trace element and isotope (TEI) inputs to ocean basins

    is less well understood. Here, we present major findings on shelf TEI biogeochemistry

    from the GEOTRACES programme as well as a proof of concept for a new method to

    estimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEI

    cycling in the Arctic, transformations within a major river estuary (Amazon), shelf sediment

    micronutrient fluxes and basin-scale estimates of submarine groundwater discharge. The

    proposed shelf flux tracer is 228-radium (T1/2 =5.75 yr), which is continuously supplied to

    the shelf from coastal aquifers, sediment porewater exchange and rivers. Model-derived shelf

    228Ra fluxes are combined with TEI/ 228Ra ratios to quantify ocean TEI fluxes from the

    western North Atlantic margin. The results from this new approach agree well with previous

    estimates for shelf Co, Fe, Mn and Zn inputs and exceed published estimates of atmospheric

    deposition by factors of approximately 3–23. Lastly, recommendations are made for additional

    GEOTRACES process studies and coastal margin-focused section cruises that will help refine

    the model and provide better insight on the mechanisms driving shelf-derived TEI fluxes

    to the ocean.

    This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element

    chemistry’.

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  • 289. Chatterjee, D.
    et al.
    Biswas, A.
    Bhowmick, S.
    Halder, D.
    Hazra, R.
    Majumder, S.
    Mukherjee-Goswami, A.
    Saha, D.
    Nath, B.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Geochemistry of arsenic in Bengal Delta Plain (West Bengal, India)2010Ingår i: Arsenic in Geosphere and Human Diseases, As 2010 - 3rd International Congress: Arsenic in the Environment, 2010, s. 125-126Konferensbidrag (Refereegranskat)
  • 290. Chen, J.H.
    et al.
    Andersson, Per S.
    Wasserburg, G.J.
    Ingri, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Uranium geochemistry in the Baltic Sea: mixing of different sources deduced from 234U - 238U1993Ingår i: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 74, nr 16, s. 329-Artikel i tidskrift (Övrigt vetenskapligt)
  • 291. Cherevatova, M.
    et al.
    Smirnov, M. Yu.
    Jones, A. G.
    Pedersen, Laust Börsting
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Becken, M.
    Biolik, M.
    Ebbing, J.
    Gradmann, S.
    Gurk, M.
    Huebert, J.
    Junge, A.
    Kamm, Jochen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Korja, T.
    Lahti, I.
    Lower, A.
    Nittinger, C.
    Savvaidis, A.
    Smirnov, M.
    Magnetotelluric array data analysis from north-west Fennoscandia2015Ingår i: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 653, s. 1-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New magnetotelluric (MT) data in north-west Fennoscandia were acquired within the framework of the project "Magnetotellurics in the Scandes" (MaSca). The project focuses on the investigation of the crustal and upper mantle lithospheric structure in the transition zone from stable Precambrian cratonic interior to passive continental margin beneath the Caledonian orogen and the Scandinavian Mountains in western Fennoscandia. An array of 59 synchronous long period and 220 broad-band MT sites was occupied in the summers of 2011 to 2013. We estimated MT transfer functions in the period range from 0.003 to 10(5) s. The Q-function multi-site multi-frequency analysis and the phase tensor were used to estimate strike and dimensionality of MT data. Dimensionality and strike analyses indicate generally 2-D behaviour of the data with 3-D effects at some sites and period bands. In this paper we present 2-D inversion of the data, 3-D inversion models are shown in the parallel paper. We choose to invert the determinant of the impedance tensor to mitigate 3-D effects in the data on our 2-D models. Seven crustal-scale and four lithospheric-scale 2-D models are presented. The resistive regions are images of the Archaean and Proterozoic basement in the east and thin Caledonian nappes in the west. The middle and lower crust of the Svecofennian province is conductive. The southern end of the Kittila Greenstone Belt is seen in the models as a strong upper to middle crustal conductor. In the Caledonides, the highly conductive alum shales are observed along the Caledonian Thrust Front. The thickest lithosphere is in the Palaeoproterozioc Svecofennian Domain, not in the Archaean. The thickness of the lithosphere is around 200 km in the north and 300 km in the south-west.

  • 292. Chi Fru, Ernest
    et al.
    Ivarsson, Magnus
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Kilias, Stephanos P
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Marone, Federica
    Paul Scherrer Institute.
    Fortin, Danielle
    Broman, Curt
    Stampanoni, Marco
    ETH Zürich.
    Fossilized iron bacteria reveal pathway to biological origin of banded iron formation.2013Ingår i: Nature Communications, ISSN 2041-1723, Vol. 4, nr 2050, s. 1-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Debates on the formation of banded iron formations in ancient ferruginous oceans are dominated by a dichotomy between abiotic and biotic iron cycling. This is fuelled by difficulties in unravelling the exact processes involved in their formation. Here we provide fossil environmental evidence for anoxygenic photoferrotrophic deposition of analogue banded iron rocks in shallow marine waters associated with an Early Quaternary hydrothermal vent field on Milos Island, Greece. Trace metal, major and rare earth elemental compositions suggest that the deposited rocks closely resemble banded iron formations of Precambrian origin. Well-preserved microbial fossils in combination with chemical data imply that band formation was linked to periodic massive encrustation of anoxygenic phototrophic biofilms by iron oxyhydroxide alternating with abiotic silica precipitation. The data implicate cyclic anoxygenic photoferrotrophy and their fossilization mechanisms in the construction of microskeletal fabrics that result in the formation of characteristic banded iron formation bands of varying silica and iron oxide ratios.

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    ChiFru_etal_2013_BIF_MS
  • 293.
    Chi Fru, Ernest
    et al.
    Stockholm University, Department of Geological Sciences.
    Rodríguez, Nathalie
    Stockholm University Department of Geological Sciences.
    Partin, Camille
    University of Saskatchewan, Canada.
    Lalonde, Stefan
    Université de Bretagne Occidentale, France.
    Andersson, Per
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Weiss, Dominik
    Imperial College, London, UK.
    El Albani, Abderrazak
    Université de Poitiers, France.
    Rodushkin, Ilia
    ALS Scandinavia, Sweden.
    Konhauser, Kurt
    University of Alberta, Canada.
    Cu isotopes in marine black shales record the Great Oxidation Event2016Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, nr 18, s. 4941-4946Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The oxygenation of the atmosphere ∼2.45–2.32 billion years ago (Ga) is one of the most significant geological events to have affected Earth’s redox history. Our understanding of the timing and processes surrounding this key transition is largely dependent on the development of redox-sensitive proxies, many of which remain unexplored. Here we report a shift from negative to positive copper isotopic compositions (δ65CuERM-AE633) in organic carbon-rich shales spanning the period 2.66–2.08 Ga. We suggest that, before 2.3 Ga, a muted oxidative supply of weathering-derived copper enriched in 65Cu, along with the preferential removal of 65Cu by iron oxides, left seawater and marine biomass depleted in 65Cu but enriched in 63Cu. As banded iron formation deposition waned and continentally sourced Cu became more important, biomass sampled a dissolved Cu reservoir that was progressively less fractionated relative to the continental pool. This evolution toward heavy δ65Cu values coincides with a shift to negative sedimentary δ56Fe values and increased marine sulfate after the Great Oxidation Event (GOE), and is traceable through Phanerozoic shales to modern marine settings, where marine dissolved and sedimentary δ65Cu values are universally positive. Our finding of an important shift in sedimentary Cu isotope compositions across the GOE provides new insights into the Precambrian marine cycling of this critical micronutrient, and demonstrates the proxy potential for sedimentary Cu isotope compositions in the study of biogeochemical cycles and oceanic redox balance in the past.

  • 294.
    Chlot, Sara
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Nitrogen and phosphorus interactions and transformations in cold-climate mine water recipients2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Process water discharged from mine sites may contain elevated concentrations of nitrogen (N) and phosphorus (P), which both are nutrients for phytoplankton and macrophytes. Thus, discharge of nutrient rich mine water can result in algal blooms, eutrophication, oxygen deficiency and changed species composition in the recipients. This thesis is focused on the speciation and transformation processes of N and P in streams and lakes receiving mine effluents from the Kiruna and Boliden mine sites. The thesis also aimed at evaluating N removal capacity of these aquatic systems. Research methods in the thesis included collection of field data, laboratory and field experiments and computer simulations. The question of limiting nutrient for production of phytoplankton and macrophytes in these mine water recipients was investigated. For this reason, total nitrogen (TN), total phosphorus (TP) and TN:TP ratios in water, sediment and macrophytes were analysed and evaluated. Depending on the ammonium concentration in the effluent at the Boliden site, TN:TP-ratios of the water column shifted from being >22, indicating P-deficiency for phytoplankton, to between 9-22, indicating a transition from N to P deficiency (co-limitation). However, water column TN:TP ratios at the Kiruna site always indicated P deficiency. On the other hand, the TN:TP ratios of macrophytes revealed that both sites may vary from N to P limitation. These aspects have implications for assessing the environmental influence of nutrient-rich mine effluents. A downstream decrease in inorganic N (NH4+ and NO3-) as well as lower concentrations during summer was observed in the receiving streams and lakes. To identify and quantify the major N transformation and removal processes responsible for these changes, a dynamic biogeochemical model was developed, calibrated and validated using hydrological and water chemistry data for the clarification pond Nya Sjön (Boliden). The model calculates concentrations of six N species and simulates the rate of 16 N transformation processes occurring in the water column and sediment as well as water-sediment and water-atmosphere interactions. The calibrated model rendered coefficients of determination (R2) of 0.93, 0.79 and 0.86 for the inorganic nitrogen species ammonium, nitrate and organic nitrogen, respectively. When applying the model in the downstream Lake Bruträsket, the corresponding R2 values were 0.86, 0.76 and 0.54. Model simulations in the two systems suggested that nitrification controlled the reaction rate of the coupled nitrification-denitrification process and that approximately 60 – 65% of permanent removal occurred though denitrification, followed by burial in the sediment (~30-35 %) (May - October). A stable nitrogen isotope (15N) was employed to trace N cycling in the various plant parts of common reed (P. australis) growing in the littoral zone of Lake Bruträsket. Isotope enrichment data indicated a significantly more effective assimilation of N in the roots. Maximum tracer uptake rates of 0.25 µg g-1 min-1 (NO3-) and 1.4 µg g-1 min-1 (NH4+) are similar to model simulated rates of macrophyte N uptake. Simulation results and results from the tracer study indicated that direct N removal through N uptake in macrophytes and phytoplankton may be of minor importance relative to nitrification and denitrification. A sediment incubation experiment using lake water and sediment from Lake Bruträsket (Boliden) resulted in a sedimentary flux of soluble reactive phosphorus (SRP) of 1.1 mg SRP m-2 d-1. Field measurements suggested that oxidation of organic matter and inorganic mining related chemicals (e.g. NH4+ and thiosalts) may result in increased internal SRP flux. These findings point to a possible interaction between the cycles of N (oxygen consumption) and P (flux from sediment) that may be important for nutrient regulation in mine water recipients. Sediment proxy data (δ13C, δ15N, C/N ratios) was used to reconstruct historical changes in organic matter (OM) accumulation in lakes receiving nutrient-rich mine waters in the Boliden and Kiruna mine sites. Sediment accumulation rates increased upwards in all cores, which correlates with an increase in suspended load in the mining effluents discharging to the systems. Similarδ15N values in dissolved inorganic N (DIN) and surface sediments most likely reflect biological assimilation of DIN and subsequent settling of phytoplankton and macrophyte organic detritus. The improved knowledge on N and P dynamics in mine water recipients can be used in selection of mine water management strategies that may lead to reduced N discharge.

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    FULLTEXT01
  • 295.
    Chlot, Sara
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Nitrogen effluents from mine sites in northern Sweden: nitrogen transformations and limiting nutrient in receiving waters2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Process water discharged from mine sites may contain elevated concentrations of nitrogen (N) and phosphorus (P), which both are nutrients for algae and aquatic plants. Thus, discharge of nutrient rich mine water can result in algal blooms, eutrophication, oxygen deficiency and changed species composition in the receiving waters. This thesis is focused on the speciation and transformation processes of N and N:P ratios in streams and lakes receiving mine effluents from the Kiruna and Boliden mine sites. In this work, a dynamic biogeochemical model was developed for the clarification pond receiving ammonium-rich mine effluents from the Boliden concentration plant. A number of such models have been developed that simulate N transformations in wastewater stabilization ponds. However, few biogeochemical models have been developed that primarily focus on simulation of processes regulating transport and removal of N in waters receiving mine effluents. The presented model calculates concentrations of six N species and simulates the rate of 16 N transformation processes occurring in the water column and sediment as well as water-sediment and water-atmosphere interactions. A six-year simulation of ammonium concentrations showed stable behaviour over time, and the calibrated model rendered coefficients of determination (R2) of 0.93, 0.79 and 0.86 for the inorganic nitrogen species ammonium, nitrate and organic nitrogen, respectively. This indicates a stable model behaviour. The simulated denitrification rate was on average five times higher than the ammonia volatilization rate, and about three times higher than the permanent burial of sedimentary nitrogen. Hence, denitrification was the most important process for the permanent removal of N. The model can be used to simulate possible measures to reduce the N load and, after some modification and recalibration, it can be applied at other mine sites affected by N-rich effluents. In addition, it was investigated which nutrient that limits bioproduction in the two aquatic systems. Total nitrogen (TN), total phosphorus (TP) and N:P ratios in water, sediment and macrophytes were used to examine (1) spatial variations within the systems, (2) differences between the systems and (3) seasonal variations. The TN content from the discharge point at the Kiruna site was on average about seven times higher than at the Boliden discharge point, while the TP content was 10 times lower than in the discharge point at the Boliden site. Depending on the ammonium concentration in the effluent at the Boliden site, N:P-ratios of the water column shifted from being >22, indicating P-deficiency, to between 9-22, indicating a transition from N to P deficiency (co-limitation). However, water column N:P ratios at the Kiruna site always indicated P deficiency. On the other hand, the N:P ratios of macrophytes revealed that both sites may vary from N to P limitation. These differences are important to consider when establishing a monitoring programme for assessing the environmental influence of nutrient rich mine effluents. Such a programme should include the major N and P species of the water as well as samples of phytoplankton, sediment and macrophytes.

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    FULLTEXT01
  • 296.
    Chlot, Sara
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    The fate of nitrogen in a lake occupied by Phragmites australis: a stable isotope tracer study2013Ingår i: Central European Geology, ISSN 1788-2281, Vol. 56, nr 2-3, s. 139-141Artikel i tidskrift (Refereegranskat)
  • 297.
    Chlot, Sara
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Using DGT to estimate soluble reactive phosphorus in a stream receiving nutrient rich mine water2013Konferensbidrag (Refereegranskat)
  • 298.
    Chlot, Sara
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Husson, Eva
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Ecke, Frauke
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Effects on nutrient regime in two recipients of nitrogen-rich mine effluents in northern Sweden2013Ingår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 31, s. 12-24Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The question of the limiting nutrient(s) for production of phytoplankton and macrophytes was explored in two contrasting freshwater systems receiving N- and P-rich mine effluents from the Boliden and Kiruna mine sites, northern Sweden. For both sites, total N (TN), total P (TP) and TN:TP mass ratios in water, sediment and macrophytes were used to examine (1) spatial variations within the systems, (2) differences between the systems and (3) seasonal variations. The TN concentration from the discharge point at the Kiruna site was about seven times higher than at the Boliden discharge point, while the TP concentration was 10 times lower than in the discharge point at the Boliden site. The majority of the studied lakes showed elevated biomass of phytoplankton, with maximum values found in Lake Bruträsket (Boliden). Mining activities have affected the nutrient regime of the two recipients by contributing to elevated TN and TP concentrations and TN:TP mass ratios as well as elevated production of phytoplankton and macrophytes compared to the reference sites. Depending on the NH4 concentration in the effluent at the Boliden site, water column TN:TP mass ratios shifted from being >22, indicating P-deficiency, to between 9 and 22, indicating a transition from N- to P-deficiency (co-limitation). However, water column TN:TP mass ratios at the Kiruna site always indicated P-deficiency, while TN:TP mass ratios of macrophytes indicate that both sites may vary from N- to P-limitation. The study suggests that for the design of efficient monitoring programmes and remediation measures, it is important to consider the major N and P species in water, phytoplankton, sediment and macrophytes.

  • 299.
    Chlot, Sara
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Siergieiev, Dmytro
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Ecke, Frauke
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Husson, Eva
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Modelling nitrogen transformations in waters receiving mine effluents2011Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 409, nr 21, s. 4585-4595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a biogeochemical model developed for a clarification pond receiving ammonium nitrogen rich discharge water from the Boliden concentration plant located in northern Sweden. Present knowledge about nitrogen (N) transformations in lakes is compiled in a dynamic model that calculates concentrations of the six N species (state variables) ammonium-N (Nam), nitrate-N (Nox), dissolved organic N in water (Norg), N in phytoplankton (Npp), in macrophytes (Nmp) and in sediment (Nsed). It also simulates the rate of 16 N transformation processes occurring in the water column and sediment as well as water–sediment and water–atmosphere interactions. The model was programmed in the software Powersim using 2008 data, whilst validation was performed using data from 2006 to 2007. The sensitivity analysis showed that the state variables are most sensitive to changes in the coefficients related to the temperature dependence of the transformation processes. A six-year simulation of Nam showed stable behaviour over time. The calibrated model rendered coefficients of determination (R2) of 0.93, 0.79 and 0.86 for Nam, Nox and Norg, respectively. Performance measures quantitatively expressing the deviation between modelled and measured data resulted in values close to zero, indicating a stable model structure. The simulated denitrification rate was on average five times higher than the ammonia volatilisation rate and about three times higher than the permanent burial of Nsed and, hence, the most important process for the permanent removal of N. The model can be used to simulate possible measures to reduce the nitrogen load and, after some modification and recalibration, it can be applied at other mine sites affected by N rich effluents.

  • 300.
    Chlot, Sara
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Carbon and nitrogen concentrations and isotopic composition in sediments of lakes receiving nitrogen rich mine effluents2011Konferensbidrag (Refereegranskat)
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