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Sökning: hsv:(NATURVETENSKAP) hsv:(Geovetenskap och miljövetenskap) > Öhlander Björn

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1.
  • Juhlin, C., et al. (författare)
  • Crustal reflectivity near the Archean-Proterozoic boundary in northern Sweden and implications for the tectonic evolution of the area
  • 2002
  • Ingår i: Geophysical Journal International. - 0956-540X .- 1365-246X. ; 150:1, s. 180-197
  • Tidskriftsartikel (refereegranskat)abstract
    • Sm–Nd isotope ratios of 1.9–1.8 Ga granitoids delineate the Archaean–Proterozoic boundary in northern Sweden, an important feature in the Fennoscandian Shield. The boundary strikes approximately WNW–ESE and is defined as a c. 20 km wide zone with juvenile Palaeoproterozoic rocks to the SSW and Archaean and Proterozoic rocks, derived to a large extent from Archaean sources, to the NNE. It therefore constitutes the strongly reworked margin of the old Archaean craton. Extrapolation of the boundary offshore into the Bothnian Bay and correlation with the marine reflection seismic BABEL Lines 2 and 3/4 indicates that the boundary dips to the south-southwest, consistent with interpretation of the Sm–Nd data. In order to tie the BABEL results with onshore surface geology and obtain detailed images of the uppermost crust a short (30 km of subsurface coverage) pilot profile was acquired in the Luleå area of northern Sweden during August 1999. The profile consisted of a high-resolution shallow component (1 kg shots) and a lower-resolution deep component (12 kg shots). Both components image most of the reflective crust, with the deep component providing a better image below 10 s. Comparison of signal penetration curves with data acquired over the Trans-Scandinavian Igneous Belt (a large batholith) indicate the transparent nature of the crust there to be caused by geological factors, not acquisition parameters. Lower crustal reflectivity patterns on the Luleå test profile are similar to those observed on the BABEL lines, suggesting the same lower crust onshore as offshore. Interpreted Archaean reflective upper crust in the NE extends below more transparent Proterozoic crust in the SW. This transparent crust contains a number of high-amplitude reflectors that may represent shear zones and/or mafic rock within granite intrusions. A marked boundary in the magnetic field in the SW has been interpreted as being the result of a gently west-dipping contact zone between meta-sediments and felsic volcanic rocks, however, the seismic data indicate a near-vertical structure in this area. By correlating the onshore and offshore seismic data we have better defined the location of the Archaean–Proterozoic boundary on the BABEL profiles. Our new interpretation of the crustal structure along the northern part of the BABEL Line 2 shows a more bi-vergent geometry than previous interpretations. Comparison of the re-interpreted crustal structure in northern Sweden with that found in the Middle Urals shows several similarities, in particular the accretion of a series of arcs to a stable craton. Based on this similarity and geological data, we deduce that a continental arc accreted to the southwestern margin of the Archaean craton at c. 1.87 Ga. Shortly thereafter, the Skellefte island arc underthrust the continental arc owing to a collision further to the southwest resulting in the bi-vergent crustal structure observed today.
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2.
  • Conrad, Sarah, et al. (författare)
  • Distribution of Fe isotopes in particles and colloids in the salinity gradient along the Lena River plume, Laptev Sea
  • 2019
  • Ingår i: Biogeosciences. - : European Geosciences Union (EGU). - 1726-4170 .- 1726-4189. ; 16:6, s. 1305-1319
  • Tidskriftsartikel (refereegranskat)abstract
    • Riverine Fe input is the primary Fe source for the ocean. This study is focused on the distribution of Fe along the Lena River freshwater plume in the Laptev Sea using samples from a 600 km long transect in front of the Lena River mouth. Separation of the particulate ( >  0.22 μm), colloidal (0.22 μm–1 kDa), and truly dissolved (<  1 kDa) fractions of Fe was carried out. The total Fe concentrations ranged from 0.2 to 57μM with Fe dominantly as particulate Fe. The loss of >  99% of particulate Fe and about 90% of the colloidal Fe was observed across the shelf, while the truly dissolved phase was almost constant across the Laptev Sea. Thus, the truly dissolved Fe could be an important source of bioavailable Fe for plankton in the central Arctic Ocean, together with the colloidal Fe. Fe-isotope analysis showed that the particulate phase and the sediment below the Lena River freshwater plume had negative δ56Fe values (relative to IRMM-14). The colloidal Fe phase showed negative δ56Fe values close to the river mouth (about -0.20 ‰) and positive δ56Fe values in the outermost stations (about +0.10 ‰). We suggest that the shelf zone acts as a sink for Fe particles and colloids with negative δ56Fe values, representing chemically reactive ferrihydrites. The positive δ56Fe values of the colloidal phase within the outer Lena River freshwater plume might represent Fe oxyhydroxides, which remain in the water column, and will be the predominant δ56Fe composition in the Arctic Ocean.
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3.
  • Alakangas, Lena, et al. (författare)
  • Norrbottens malm- och mineralresurs och dess potentiella betydelse för innovation, samhälle och miljö
  • 2014
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Gruvindustrins betydelse för samhällsutveckling och infrastruktur i Sverige och inte minst i Norrbottens län är mycket stor. De geologiska förutsättningarna att hitta nya brytvärda förekomster i Norrbotten är goda. Länet är tillsammans med Västerbotten en av Europas viktigaste regioner för utvinning av metaller. Det syns också i den nyligen framtagna regionala mineralstrategin för Norrbotten och Västerbotten. Visionen för den regionala mineralstrategin: ”Genom långsiktigt hållbart nyttjande av Norrbottens och Västerbottens läns mineralresurser har ytterligare tillväxt skapats i regionen och hela Sverige. Vi har utvecklat och stärkt vår ställning som ledande gruv- och mineralnation.”Eftersom framtidspotentialen för gruvnäringen är mycket god men okunnigheten hos både allmänhet och beslutsfattare om näringens betydelse för innovation och samhällsutveckling är stor, kopplat med en utbredd oro för miljöpåverkan, måste dessa viktiga framtidsfrågor belysas. Med finansiering från Länsstyrelsen i Norrbotten bedrevs därför under första hälften av 2014 en förstudie som syftade till att sammanfatta kunskapsläget om framtidens gruvindustri i Norrbotten. Resultaten av förstudien redovisas i den här rapporten. En viktig slutsats är att det under nästa strukturfondsperiod (med start 2015) behövs ett framtidsinriktat forskningsprogram för att belysa de möjligheter som finns. Denna förstudie utgör grund för en kommande ansökan till strukturfonderna. Kompetensen som finns vid Luleå tekniska universitet, Sveriges centrum för gruvrelaterad forskning och utbildning, bör användas för att studera troliga framtidsmöjligheter och hur de ska kunna användas för att få en så positiv utveckling som möjligt för länet. Projektet bör innehålla följande tre huvudinriktningar, som naturligtvis hör ihop:Vilka malm- och mineralresurser finns det potential för i Norrbotten, och vilka kommer sannolikt att exploateras i framtiden?Vad kommer den exploateringen att ha för betydelse för innovation och samhällsutveckling?Vad kommer den exploateringen att få för miljöeffekter och hur ska man göra för att minska miljöbelastningen?En annan slutsats är att nedlagda gruvområden inte måste ses som förstörd natur. Betydande mervärden som gruvturism skulle kunna skapas om vilja, kreativitet och beslutsamhet finns. Detta är ett givet utvecklingsområde där småföretag och entreprenörer kan göra stor insats om de politiska och myndighetsmässiga förutsättningarna finns. Dessa aspekter skulle också kunna belysas i det föreslagna forskningsprogrammet eller i ett eget projekt.
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6.
  • Jia, Yu, et al. (författare)
  • Elemental mobility in sulfidic mine tailings reclaimed with paper mill by-products as sealing materials
  • 2017
  • Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 24:25, s. 20372-20389
  • Tidskriftsartikel (refereegranskat)abstract
    • Sealing layers made of two alkaline paper mill by-products, fly ash and green liquor dregs, were placed on top of 50-year-old sulfide-containing tailings as a full-scale remediation approach. The performance and effectiveness of the sealing layers with high water content for an oxygen barrier and low hydraulic conductivity for a sealing layer in preventing the formation of acid rock drainage were evaluated 5 years after the remediation. The leaching behavior of the covered tailings was studied using batch leaching tests (L/S ratio 10 L/kg). The leaching results revealed that, in general, the dregs- and ash-covered tailings released relatively lower concentrations of many elements contained in acid rock drainage compared to those from the uncovered tailings. A change in the chemical composition and mineralogical state of the tailings was observed for the tailings beneath the covers. The increase in pH caused by the alkaline materials promoted metal precipitation. Geochemical modeling using PHREEQC confirmed most of the geochemical changes of the covered tailings. Both the ash and dregs showed potential to function as sealing materials in terms of their geochemical properties. However, mobilization of Zn and Ni from the lower part of the dregs-covered tailings was observed. The same phenomenon was observed for the lower part of the ash-covered tailings. Ash showed advantages over dregs as a cover material; based on geochemical studies, the ash immobilized more elements than the dregs did. Lysimeters were installed below the sealing layers, and infiltrating water chemistry and hydrology were studied to monitor the amount and quality of the leachate percolating through.
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7.
  • Jia, Yu, et al. (författare)
  • Geotechnical and chemical characterization of field-applied fly ash as sealing material over mine tailings
  • 2019
  • Ingår i: International Journal of Environmental Science and Technology. - : Springer. - 1735-1472 .- 1735-2630. ; 16:3, s. 1701-1710
  • Tidskriftsartikel (refereegranskat)abstract
    • The present study addresses the geotechnical and chemical properties of sealing materials using a paper mill by-product, fly ash, on top of sulfide-bearing mine waste tailings after 5 years of field application. From a geotechnical perspective, the low in situ bulk density (≤ 1500 kg/m3) ensured a high degree of water saturation (90.2%) for the field-applied ash. The chemical characteristics and behaviors of the fly ash samples reflected a high long-term leaching capacity (liquid-to-solid ratio of 10 cm3/g) and high alkalinity (liquid-to-solid ratio of up to 500 cm3/g). The laboratory leaching results suggested that none of the elements released from the field-applied ash exceeded the EU limits for inert materials, and the concentrations of elements were far below the limits for hazardous materials at landfill sites. Based on the in situ and laboratory characterizations of the field-applied ash, the fly ash sealing material was considered geotechnically stable. However, a number of geotechnical parameters could not be measured due to the cementation of the ash. Moreover, the chemical composition of the field-applied ash exhibited considerable variations when compared with that of the raw ash generated from the same paper mill. Overall, the field-applied ash displayed high alkalinity and effectively buffered the acid generated from sulfidic tailings for long-term sealing purposes.
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8.
  • Mellqvist, Claes, et al. (författare)
  • Some aspects on the subdivision of the Haparanda and Jörn intrusive suites in northern Sweden
  • 2003
  • Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 125:2, s. 77-85
  • Tidskriftsartikel (refereegranskat)abstract
    • The geographical subdivision between the Haparanda and the Jörn suites of intrusive rocks in northern Sweden has not been very well defined. Early stratigraphical schemes placed these two granitoid suites in two separate orogenic cycles, where the Jörn belonged to the older cycle and Haparanda to the younger. Our present knowledge regarding the isotopic ages of these rocks in northern Sweden has changed this view, but has also made the distinction between the two suites less clear. Based on recent Sm–Nd isotopic work combined with geochemistry and some new U–Pb zircon data, we point out some similarities as well as some differences between the Jörn and Haparanda suites of rocks. Two U–Pb zircon age determinations performed give upper intercept ages of 1891±32 Ma and 1861±19 Ma which are interpreted as maximum ages. The two samples are taken from the Luleå area, on each side of the Archaean–Proterozoic boundary, as defined by Sm–Nd isotopic analyses of c.1.9 Ga old intrusive rocks combined with the southern limit of outcropping Archaean rocks. On the basis of new results together with results from previous studies of areas north and south of the Archaean–Proterozoic boundary, we also suggest how to separate the Haparanda and Jörn suites of rocks due to their geochemical, and isotope geochemical, characteristics. The Haparanda suite generally has negative εNd(t) values and was formed within or in marginal parts of the Archaean craton. The Jörn suite was formed in an juvenile, island-arc terrane, that was accreted to the Archaean craton during the later, collisional stages of the Svecokarelian orogeny. In a similar way, we connect the Haparanda suite of rocks with the Archaean craton, and the Jörn suite of rocks with Svecofennian juvenile crust.
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9.
  • Pallavicini, Nicola, et al. (författare)
  • Ranges of B, Cd, Cr, Cu, Fe, Pb, Sr, Tl, and Zn Concentrations and Isotope Ratios in Environmental Matrices from an Urban Area
  • 2018
  • Ingår i: Journal of Spectroscopy. - : Hindawi Publishing Corporation. - 2314-4920 .- 2314-4939. ; , s. 1-17
  • Tidskriftsartikel (refereegranskat)abstract
    • Isotopic information may provide powerful insight into the elemental cycling processes which occur in natural compartments. Further implementation of isotopic techniques in natural sciences requires a better understanding of the range of elemental and isotopic compositional variability in environmental matrices. This study assesses the local-scale concentration and isotopic composition variability of nine elements: boron (B), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), strontium (Sr), thallium (Tl), and zinc (Zn) in lysimetric waters, mushrooms, litter, needles, leaves, and lichens. Sequential extractions were also performed on soil samples from 6 depth profiles providing more detailed information on the variability of elemental concentrations and isotope ratios between the elemental pools present in soil. For most of the sample types studied the range of isotopic variability between samples spans almost the entire ranges reported in the literature for natural samples. These results represent a starting point for discussing the role of natural variability in isotopic studies (for example, as a limiting factor in the use of isotopic mixing models) and a baseline for future in-depth studies examining the controls on isotope fraction in natural systems
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10.
  • Qureshi, Asif, 1986-, et al. (författare)
  • Effects of the co-disposal of lignite fly ash and coal mine waste rocks on AMD and leachate quality
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Lignite fly ash (FA) and waste rocks (WRs) were mixed in three different ratios (1:1, 1:3 and 1:5) and studied to compare the effects of adding FA on AMD generation from coal mining WRs, leachability of elements and the potential occurrence of secondary minerals. FA mixed with WRs showed significant differences in pH levels compared to previous research. The 1:1 mixture performed best of all the three mixtures in terms of pH and leachability of elements, mainly due to the higher proportion of FA in the mixture. The pH in the 1:1 mixtures varied between 3.3 – 5.1 compared to other mixtures (2.3­ – 3.5). Iron and SO42- leached considerably less from the 1:1 mixture compared to the others, indicating that the oxidation of sulphides was weaker in this mixture. Aluminium leached to a high degree from all mixtures, with concentrations varying from mg L-1–g L-1. The reason behind this increase is probably the addition of FA which, due to acidic conditions and the composition of the FA, increases the availability of Al. For the same reason, high concentrations of Mn and Zn were also measured. Geochemical modelling indicates that the 1:1 mixture performs better in terms of precipitation of Al3+ minerals, whereas Fe3+ minerals precipitated more in mixtures containing less FA. These results suggest that, with time, the pores could possibly be filled with these secondary minerals and sulphate salts (followed by a decrease in sulphide oxidation), improving the pore water pH and decreasing the leachability of elements. Since grain size plays a crucial role in the reactivity of sulphides, there is a risk that the results from the leaching tests may have been influenced by crushing and milling of the WR samples.
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