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  • 1. Alegret, Joan
    et al.
    Käll, Mikael
    Johansson, Peter
    Örebro universitet, Institutionen för naturvetenskap.
    Top-down extended meshing algorithm and its applications to Green's tensor nano-optics calculations2007Inngår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, ISSN 1063-651X, E-ISSN 1095-3787, Vol. 75, nr 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a computational algorithm which speeds up Green's tensor nano-optics calculations by means of optimizing the mesh that represents the system we want to investigate. The algorithm automates the process of creating a variable-size mesh that describes an arbitrary nanostructure. The total number of elements of this mesh is smaller than that of a regular mesh representing the same structure, and thus the Green's tensor calculations can be performed faster. Precision, however, is kept at a similar level than for the regular mesh. Typically, the algorithm yields a mesh that speeds up Green's tensor calculations by a factor of 4, while giving a maximum error in the field magnitude of about 5%. The speed-up factor makes it very suitable for otherwise lengthy calculations, and the error should be acceptable for most applications.

  • 2.
    Allard, Bert
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Greis, Christina
    Örebro universitet, Institutionen för naturvetenskap.
    Pettersson, Håkan
    Linköpng Univ.
    Düker, Anders
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Redistribution of Pu, Am, Cs and Np in salt marsh sediment: Wigtown Merse, Irish Sea2009Inngår i: 8th International Conference on Methods and Applications of Radioanalytical Chemistry (MARC VIII) / [ed] Rolf Zeisler, Kenan Ünlü, Susan Heller-Zeisler, Melville, N.Y.: American Institute of Physics (AIP), 2009, s. 1-24Konferansepaper (Fagfellevurdert)
  • 3.
    Allard, Bert
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Greis, Christina
    Örebro universitet, Institutionen för naturvetenskap.
    Pettersson, Håkan
    Düker, Anders
    Redistribution pf Pu, Am, Cs and Np in salt marsh sediment - Wigtown Merse, Irish SeaManuskript (Annet vitenskapelig)
  • 4.
    Andershed, Henrik A.
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Kerr, Margaret
    Örebro universitet, Institutionen för beteende-, social- och rättsvetenskap.
    Stattin, Håkan
    Örebro universitet, Institutionen för beteende-, social- och rättsvetenskap.
    Levander, Sten
    Psychopathic traits in non-referred youths: a new assessment tool2002Inngår i: Psychopaths: current international perspectives / [ed] Eric Blaauw, Lorraine Sheridan, Den Haag: Elsevier , 2002, s. 131-158Kapittel i bok, del av antologi (Fagfellevurdert)
  • 5.
    Andreasson, Henrik
    et al.
    Örebro universitet, Institutionen för teknik.
    Lilienthal, Achim
    Örebro universitet, Institutionen för naturvetenskap. aass.
    Vision aided 3D laser scanner based registration2007Inngår i: ECMR 2007: Proceedings of the European Conference on Mobile Robots, 2007, s. 192-197Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes a vision and 3D laser based registration approach which utilizes visual features to identify correspondences. Visual features are obtained from the images of a standard color camera and the depth of these features is determined by interpolating between the scanning points of a 3D laser range scanner, taking into consideration the visual information in the neighbourhood of the respective visual feature. The 3D laser scanner is also used to determine a position covariance estimate of the visual feature. To exploit these covariance estimates, an ICP algorithm based on the Mahalanobis distance is applied. Initial experimental results are presented in a real world indoor laboratory environment

  • 6.
    Andreasson, Henrik
    et al.
    Örebro universitet, Institutionen för teknik.
    Magnusson, Martin
    Örebro universitet, Institutionen för teknik.
    Lilienthal, Achim
    Örebro universitet, Institutionen för naturvetenskap.
    Has something changed here?: Autonomous difference detection for security patrol robots2007Inngår i: 2007 IEEE/RSJ international conference on intelligent robots and systems, New York, NY, USA: IEEE, 2007, s. 3429-3435, artikkel-id 4399381Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a system for autonomous change detection with a security patrol robot. In an initial step a reference model of the environment is created and changes are then detected with respect to the reference model as differences in coloured 3D point clouds, which are obtained from a 3D laser range scanner and a CCD camera. The suggested approach introduces several novel aspects, including a registration method that utilizes local visual features to determine point correspondences (thus essentially working without an initial pose estimate) and the 3D-NDT representation with adaptive cell size to efficiently represent both the spatial and colour aspects of the reference model. Apart from a detailed description of the individual parts of the difference detection system, a qualitative experimental evaluation in an indoor lab environment is presented, which demonstrates that the suggested system is able register and detect changes in spatial 3D data and also to detect changes that occur in colour space and are not observable using range values only.

  • 7.
    Angelstam, Per
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Mikusinski, Grzegorz
    Örebro universitet, Institutionen för naturvetenskap. Swed. Univ. of Agricultural Sciences, Sweden.
    Rönnbäck, Britt-Inger
    Div. of Geogr. Info. Technology, Luleå University of Technology, Sweden; Luleå University of Technology, Sweden; Swedish Space Corporation, Swedish Land Survey, Sweden; Dept. of Environmental Engineering, Geographical Information Technology, Luleå University of Technology, Luleå, Sweden .
    Östman, Anders
    Luleå University of Technology, Sweden; Dept. of Environmental Engineering, Geographical Information Technology, Luleå University of Technology, Luleå, Sweden; Intergraph, Sweden .
    Lazdinis, Marius
    Lithuanian Agricultural University, Lithuania; Southern Illinois University, United States; Lithuanian Ministry of Environment, Lithuania; Department of Conservation Biology, Swedish University of Agriculture, Sweden; Swed. Univ. of Agricultural Sciences, Umeå, Sweden.
    Roberge, Jean-Michel
    Swed. Univ. of Agricultural Sciences, Umeå, Sweden; Université Laval, Canada; Department of Conservation Biology, Swed. Univ. of Agricultural Sciences, Sweden .
    Arnberg, Wolter
    Stockholm University, Department of Physical Geography, Stockholm, Sweden .
    Olsson, Jan
    Örebro universitet, Institutionen för humaniora, utbildnings- och samhällsvetenskap.
    Two-dimensional gap analysis: a tool for efficient conservation planning and biodiversity policy implementation2003Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 32, nr 8, s. 527-534Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The maintenance of biodiversity by securing representative and well-connected habitat networks in managed landscapes requires a wise combination of protection, management, and restoration of habitats at several scales. We suggest that the integration of natural and social sciences in the form of "Two-dimensional gap analysis" is an efficient tool for the implementation of biodiversity policies. The tool links biologically relevant "horizontal" ecological issues with "vertical" issues related to institutions and other societal issues. Using forest biodiversity as an example, we illustrate how one can combine ecological and institutional aspects of biodiversity conservation, thus facilitating environmentally sustainable regional development. In particular, we use regional gap analysis for identification of focal forest types, habitat modelling for ascertaining the functional connectivity of "green infrastructures", as tools for the horizontal gap analysis. For the vertical dimension we suggest how the social sciences can be used for assessing the success in the implementation of biodiversity policies in real landscapes by identifying institutional obstacles while implementing policies. We argue that this interdisciplinary approach could be applied in a whole range of other environments including other terrestrial biota and aquatic ecosystems where functional habitat connectivity, nonlinear response to habitat loss and a multitude of economic and social interests co-occur in the same landscape.

  • 8. Belpomme, D.
    et al.
    Irigaray, P.
    Hardell, Lennart
    Örebro universitet, Institutionen för naturvetenskap.
    Clapp, R.
    Montagnier, L.
    Epstein, S.
    Sasco, A. J.
    The multitude and diversity of environmental carcinogens2007Inngår i: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 105, nr 3, s. 414-429Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have recently proposed that lifestyle-related factors, screening and aging cannot fully account for the present overall growing incidence of cancer. In order to propose the concept that in addition to lifestyle related factors, exogenous environmental factors may play a more important role in carcinogenesis than it is expected, and may therefore account for the growing incidence of cancer, we overview herein environmental factors, rated as certainly or potentially carcinogenic by the International Agency for Research on Cancer (IARC). We thus analyze the carcinogenic effect of microorganisms (including viruses), radiations (including radioactivity, UV and pulsed electromagnetic fields) and xenochemicals. Chemicals related to environmental pollution appear to be of critical importance, since they can induce occupational cancers as well as other cancers. Of major concerns are: outdoor air pollution by carbon particles associated with polycyclic aromatic hydrocarbons; indoor air pollution by environmental tobacco smoke, formaldehyde and volatile organic compounds such as benzene and 1,3 butadiene, which may particularly affect children, and food pollution by food additives and by carcinogenic contaminants such as nitrates, pesticides, dioxins and other organochlorines. In addition, carcinogenic metals and metalloids, pharmaceutical medicines and cosmetics may be involved. Although the risk fraction attributable to environmental factors is still unknown, this long list of carcinogenic and especially mutagenic factors supports our working hypothesis according to which numerous cancers may in fact be caused by the recent modification of our environment. (C) 2007 Elsevier Inc. All rights reserved.

  • 9. Belpomme, D.
    et al.
    Irigaray, P.
    Sasco, A. J.
    Newby, J. A.
    Howard, V.
    Clapp, R.
    Hardell, Lennart
    Örebro universitet, Institutionen för naturvetenskap.
    The growing incidence of cancer: Role of lifestyle and screening detection (Review)2007Inngår i: International Journal of Oncology, ISSN 1019-6439, Vol. 30, nr 5, s. 1037-1049Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The increasing incidence of a variety of cancers after the Second World War confronts scientists with the question of their origin. In Western countries, expansion and ageing of the population, as well as progress in cancer detection using new diagnostic and screening tests cannot fully account for the observed growing incidence of cancer. Our hypothesis is that environmental factors play a more important role in cancer genesis than it is usually agreed: i) over the last 2-3 decades, alcohol consumption and tobacco smoking in men have significantly decreased; ii) obesity is increasing in many countries, but the growing incidence of cancer also concerns cancers not related to obesity nor to other lifestyle-related factors; iii) there is evidence that the environment has changed over the same time scale as the recent rise in cancer incidence, and that this change included the accumulation of many new carcinogenic factors in the environment; iv) genetic susceptibility to cancer due to genetic polymorphism cannot have changed over one generation and actually favours the role of exogenous factors through gene-environment interactions; v) age is not the unique factor to be considered since the rising incidence of cancers is seen across all age categories, including children; vi) the fetus is specifically vulnerable to exogenous factors. A fetal exposure during a critical window period may explain why current epidemiological studies may be negative in adults. We therefore propose that the involuntary exposure to many carcinogens in the environment contributes to the rising trend in cancer incidence.

  • 10.
    Benyamine, Michelle
    Örebro universitet, Institutionen för naturvetenskap.
    Theoretical disputes and practical environmental dilemmas: an interdisciplinary study2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of this thesis is to analyse the scientific basis for diverging recommendations in environmental management. A further aim of this study is to discuss the links and interactions between disciplines related to science of environmental issues, and between natural science and practice in dealing with environmental management and ecological sustainability. The question at issue was whether ontological (how the world is constituted) and epistemological (how achieve knowledge about the world) differences between disciplines lead to opposing conclusions. Scientific disputes were selected systematically to examine and analyse the theoretical characteristics and reasons of these disputes. Two case studies were selected: forest nitrogen fertilisation and constructed wetlands. Content analysis was used to study the theoretical content of and the reasons for the disputes within these two scientific areas. Research articles published in peer-reviewed journals, conference proceedings, and publications in anthologies were chosen as the empirical material.

     

    The results show that theoretical disputes arise from the diversity of disciplines and fragmentation of theoretical frameworks. The conclusions are that one way to overcome scientific disputes and achieve common knowledge and solutions to environmental problems is to identify and compare values and principles of the different scientific research traditions.

    Delarbeid
    1. Forest nitrogen fertilisation
    Åpne denne publikasjonen i ny fane eller vindu >>Forest nitrogen fertilisation
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Miljövetenskap
    Identifikatorer
    urn:nbn:se:oru:diva-15930 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2017-10-17bibliografisk kontrollert
    2. Why forest nitrogen fertilization is debated
    Åpne denne publikasjonen i ny fane eller vindu >>Why forest nitrogen fertilization is debated
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Miljövetenskap
    Identifikatorer
    urn:nbn:se:oru:diva-15931 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2019-03-26bibliografisk kontrollert
    3. Multi-objective environmental management in constructed wetlands
    Åpne denne publikasjonen i ny fane eller vindu >>Multi-objective environmental management in constructed wetlands
    2004 (engelsk)Inngår i: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 90, nr 1-3, s. 171-185Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We examined multi-objective environmental management as applied to pursuing concurrent goals of water treatment, biodiversity and promotion of recreation in constructed wetlands. A case study of a wetland established to treat landfill leachate, increase biodiversity, and promote recreation was evaluated. The study showed that attempts to combine pollution management with activities promoting biodiversity or recreation are problematic in constructed wetlands. This could be because the typical single-objective focus of scientific research leads to contradictions when planning, implementing and assessing the multi-objective use of wetlands. In the specific case of wetland filters for landfill leachate treatment, biodiversity, and recreation, there is a need for further research that meet practical needs to secure positive outcomes.

    HSV kategori
    Forskningsprogram
    Miljövetenskap
    Identifikatorer
    urn:nbn:se:oru:diva-5198 (URN)10.1023/B:EMAS.0000003577.22824.8e (DOI)
    Tilgjengelig fra: 2009-01-30 Laget: 2009-01-30 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    4. Contradictions in multiobjective constructed wetland research
    Åpne denne publikasjonen i ny fane eller vindu >>Contradictions in multiobjective constructed wetland research
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Miljövetenskap
    Identifikatorer
    urn:nbn:se:oru:diva-15932 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2017-10-17bibliografisk kontrollert
    5. Site characteristics and nitrogen fertilization effects
    Åpne denne publikasjonen i ny fane eller vindu >>Site characteristics and nitrogen fertilization effects
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Miljövetenskap
    Identifikatorer
    urn:nbn:se:oru:diva-15933 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2017-10-17bibliografisk kontrollert
  • 11.
    Benyamine, Michelle
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Bäckström, Mattias
    Örebro universitet, Institutionen för naturvetenskap.
    Sandén, Per
    Multi-objective environmental management in constructed wetlands2004Inngår i: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 90, nr 1-3, s. 171-185Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We examined multi-objective environmental management as applied to pursuing concurrent goals of water treatment, biodiversity and promotion of recreation in constructed wetlands. A case study of a wetland established to treat landfill leachate, increase biodiversity, and promote recreation was evaluated. The study showed that attempts to combine pollution management with activities promoting biodiversity or recreation are problematic in constructed wetlands. This could be because the typical single-objective focus of scientific research leads to contradictions when planning, implementing and assessing the multi-objective use of wetlands. In the specific case of wetland filters for landfill leachate treatment, biodiversity, and recreation, there is a need for further research that meet practical needs to secure positive outcomes.

  • 12.
    Benyamine, Michelle
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Lidskog, Rolf
    Örebro universitet, Institutionen för samhällsvetenskap.
    Sandén, Per
    Forest nitrogen fertilisationManuskript (preprint) (Annet vitenskapelig)
  • 13.
    Benyamine, Michelle
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Lidskog, Rolf
    Örebro universitet, Institutionen för samhällsvetenskap.
    Sandén, Per
    Why forest nitrogen fertilization is debatedManuskript (preprint) (Annet vitenskapelig)
  • 14.
    Benyamine, Michelle
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Sandén, Per
    Contradictions in multiobjective constructed wetland researchManuskript (preprint) (Annet vitenskapelig)
  • 15.
    Benyamine, Michelle
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Sandén, Per
    Site characteristics and nitrogen fertilization effectsManuskript (preprint) (Annet vitenskapelig)
  • 16.
    Berg, A. Håkan
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Thomas, Peter
    Olsson, Per-Erik
    Örebro universitet, Institutionen för naturvetenskap.
    Biochemical characterization of the Arctic char (Salvelinus alpinus) ovarian progestin membrane receptor2005Inngår i: Reproductive Biology and Endocrinology, ISSN 1477-7827, E-ISSN 1477-7827, Vol. 3, s. 64-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Membrane progestin receptors are involved in oocyte maturation in teleosts. However, the maturation-inducing steroid (MIS) does not appear to be conserved among species and several progestins may fulfill this function. So far, complete biochemical characterization has only been performed on a few species. In the present study we have characterized the membrane progestin receptor in Arctic char (Salvelinus alpinus) and show that the 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) receptor also binds several xenobiotics, thus rendering oocyte maturation sensitive to environmental pollutants. We identified a single class of high affinity (Kd, 13.8 +/- 1.1 nM), low capacity (Bmax, 1.6 +/- 0.6 pmol/g ovary) binding sites by saturation and Scatchard analyses. Receptor binding displayed rapid association and dissociation kinetics typical of steroid membrane receptors, with t1/2 s of less than 1 minute. The 17,20beta-P binding also displayed tissue specificity with high, saturable, and specific 17,20beta-P binding detected in ovaries, heart and gills while no specific binding was observed in muscle, brain or liver. Changes in 17,20beta-P binding during oocyte maturation were consistent with its identity as the oocyte MIS membrane receptor. Incubation of fully-grown ovarian follicles with gonadotropin induced oocyte maturation, which was accompanied by a five-fold increase in 17,20beta-P receptor binding. In addition, competition studies with a variety of steroids revealed that receptor binding is highly specific for 17,20beta-P, the likely maturation-inducing steroid (MIS) in Arctic char. The relative-binding affinities of all the other progestogens and steroids tested were less than 5% of that of 17,20beta-P for the receptor. Several ortho, para derivatives of DDT also showed weak binding affinity for the 17,20beta-P receptor supporting the hypothesis that xenobiotics may bind steroid receptors on the oocyte's surface and might thereby interfere with oocyte growth and maturation.

  • 17. Bergknut, Magnus
    et al.
    Kucera, Adam
    Frech, Kristina
    Andersson, Erika
    Örebro universitet, Institutionen för naturvetenskap.
    Engwall, Magnus
    Örebro universitet, Institutionen för naturvetenskap.
    Rannug, Ulf
    Koci, Vladimir
    Andersson, Patrik L.
    Haglund, Peter
    Tysklind, Mats
    Identification of potentially toxic compounds in complex extracts of environmental samples using gas chromatography-mass spectrometry and multivariate data analysis2007Inngår i: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 26, nr 2, s. 208-217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, we examined 31 samples of varying chemical composition, including samples of soils from gasworks, coke production sites, and sites where wood preservatives were heavily used; ash and soot from municipal solid waste incinerators; antiskid sand; and dust from areas with heavy road traffic. The samples were comprehensively chemically characterized, especially their polycyclic aromatic compound contents, using gas chromatography-time-of-flight mass spectrometry, whereas their biological effects were assessed using dehydrogenase activity, root growth (Hordeum vulgare), reproduction of springtails (Folsomia candida), algal growth (Desmodesmus subspicatus), germinability (Sinapis alba), Vibrio fischeri, DR-CALUX, and Ames Salmonella assays. The number of compounds detected in the samples ranged from 123 to 527. Using the multivariate regression technique of partial-least-squares projections to latent structures, it was possible to find individual compounds that exhibited strong correlations with the different biological responses. Some of the results, however, indicate that a broader chemical characterization may be needed to identify all the compounds that may cause the measured biological responses.

  • 18. Bierbrauer, Jürgen
    et al.
    Schellwat, Holger
    Örebro universitet, Institutionen för naturvetenskap.
    Almost independent and weakly biased arrays: efficient constructions and cryptologic applications2000Inngår i: Advances in cryptology: CRYPTO 2000 / [ed] Mihir Bellare, Springer Berlin/Heidelberg, 2000, s. 533-543Konferansepaper (Annet vitenskapelig)
  • 19. Bierbrauer, Jürgen
    et al.
    Schellwat, Holger
    Örebro universitet, Institutionen för naturvetenskap.
    Weakly biased arrays, almost independent arrays and error-correcting codes2001Inngår i: Codes and association schemes / [ed] Alexander Barg, Simon Litsyn, Providence, R.I.: American Mathematical Society , 2001, s. 33-46Konferansepaper (Annet vitenskapelig)
  • 20.
    Birgersson, Evert
    Örebro universitet, Institutionen för naturvetenskap.
    Determination of binary fission-fragment yields in the reaction 251Cf(nth, f) and Verification of nuclear reaction theory predictions of fission-fragment distributions in the reaction 238U(n, f)2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Neutron-induced fission has been studied at different excitation energies of the compound nucleus by measurements on the two fissioning systems, 252Cf* and 239U*.

    For the first time, the light fission fragment yields from the reaction 251Cf(nth, f) have been measured with high resolution. This experiment was performed with the recoil mass spectrometer LOHENGRIN at ILL in Grenoble, France. When the results from this work, where the compound nucleus is at thermal excitation, are compared to the spontaneous fission of 252Cf, enhanced emission yields as well as an increased mean kinetic energy is observed around A = 115. This suggests the existence of an additional super-deformed fission mode in 252Cf.

    The reaction 238U(n, f) was studied using the 2E-technique with a double Frisch grid ionization chamber. Fission fragment mass, energy and angular distributions were determined for incident neutron energies between 0.9 and 2.0 MeV. The experiments were performed at the Van de Graaff accelerator of IRMM in Geel, Belgium. This is the first measurement of the mass distribution for incident neutron energies around 0.9 MeV. The motivation for studying 238U(n, f) was to verify theoretical predictions of the mass distribution at the vibrational resonance in the fission cross section at 0.9 MeV. However, the predicted changes in fission fragment distributions could not be confirmed.

    A precise modelling of the fission process for the minor actinides becomes very important for future generation IV and accelerator driven nuclear reactors. Since fission fragment distributions depend on the excitation of the fissioning system, so does the number of delayed neutrons, which are one of the safety parameters in a reactor.

    Delarbeid
    1. Binary fission-fragment yields from the reaction 251Cf(nth, f)
    Åpne denne publikasjonen i ny fane eller vindu >>Binary fission-fragment yields from the reaction 251Cf(nth, f)
    Vise andre…
    2005 (engelsk)Inngår i: Nuclear fission and fission-product spectroscopy: 3rd international workshop on nuclear fission and fission-product spectroscopy, American Institute of Physics , 2005, s. 349-352Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    The recoil mass spectrometer LOHENGRIN of the Laue-Langevin Institute, Grenoble has been used to measure the light fission-fragment mass yield and kinetic energy distributions from neutron-induced 252Cf*, using 251Cf as target material. ©2005 American Institute of Physics

    sted, utgiver, år, opplag, sider
    American Institute of Physics, 2005
    HSV kategori
    Forskningsprogram
    Fysik
    Identifikatorer
    urn:nbn:se:oru:diva-11214 (URN)10.1063/1.2137266 (DOI)0-7354-0288-4 (ISBN)
    Konferanse
    The 3rd International Workshop on NUCLEAR FISSION AND FISSION-PRODUCT SPECTROSCOPY, Château de Cadarache, Saint Paul lez Durance, France, May 11-14, 2005
    Tilgjengelig fra: 2007-09-03 Laget: 2007-09-03 Sist oppdatert: 2017-10-18bibliografisk kontrollert
    2. Light fission-fragment mass distribution from the reaction 251Cf(nth, f)
    Åpne denne publikasjonen i ny fane eller vindu >>Light fission-fragment mass distribution from the reaction 251Cf(nth, f)
    Vise andre…
    2007 (engelsk)Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 791, nr 1-2, s. 1-23Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    For mass numbers A = 80 to 124 the recoil mass spectrometer LOHENGRIN of the Institute Laue-Langevin in Grenoble was used to measure with high resolution the light fission-fragment mass yields and kinetic energy distributions from thermal-neutron induced fission of 252Cf* for the first time, using 251Cf as target material. The obtained mean light fragment mass AL = (107 ± 2) and the corresponding mean kinetic energy Ek,L = (103±2) MeV are within the expected trend. Emission yields around A = 115 are enhanced and the corresponding mean kinetic energy is higher compared to spontaneous fission of 252Cf. This could be explained by the existence of an additional super-deformed fission mode.

    sted, utgiver, år, opplag, sider
    Amsterdam: Elsevier, 2007
    Emneord
    Nuclear reactions, 251Cf(nth, f ), Californium-251, Neutron-induced fission, Fission modes, Minor Actinides, Transmutation, Fission-fragment spectroscopy
    HSV kategori
    Forskningsprogram
    Fysik
    Identifikatorer
    urn:nbn:se:oru:diva-4080 (URN)10.1016/j.nuclphysa.2007.04.018 (DOI)
    Tilgjengelig fra: 2007-10-30 Laget: 2007-10-30 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    3. Properties of the reaction 238U(n, f) at the vibrational resonances
    Åpne denne publikasjonen i ny fane eller vindu >>Properties of the reaction 238U(n, f) at the vibrational resonances
    2009 (engelsk)Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 817, nr 1-4, s. 1-34Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Recent fission cross-section calculations for the reaction 238U(n, f ), based on an extended statistical model, predict a significant change of fission fragment properties, such as the mean mass by A = 1.5 and a notable increase in total kinetic energy in the region of the vibrational resonance at an incident neutron energy En = 0.9 MeV. This model includes individual fission cross-sections by the asymmetric standard 1 (S1) and standard 2 (S2) as well as the symmetric super-long (SL) mode. In order to verify the model predictions, a dedicated experiment on 238U has been carried out to measure fission-fragment mass yield distributions for incident neutron energies from En = 2.0 MeV down to 0.9 MeV, where the fission characteristics at the vibrational resonance at En = 0.9 MeV were investigated for the first time. The previously reported distinct structure in the angular anisotropy around En = 1.2 and 1.6 MeV wasobserved at En = 0.9 MeV as well. The predicted large changes in fission fragment mass yield and total kinetic energy could not be confirmed. In the resonance the mean total kinetic energy is only about 0.5 MeV higher than at En = 1.8 MeV. At the same time, a slight decrease of the mean heavy fragment mass was observed, probably indicating a slightly increased contribution of the S1 fission mode.

    sted, utgiver, år, opplag, sider
    Amsterdam: Elsevier, 2009
    Emneord
    Nuclear reactions 238U(n, f ), E = 0.9–2.0 MeV; measured/analyzed fission fragment mass yields and
    HSV kategori
    Forskningsprogram
    Fysik
    Identifikatorer
    urn:nbn:se:oru:diva-5485 (URN)10.1016/j.nuclphysa.2008.12.001 (DOI)000263449200001 ()2-s2.0-58149293406 (Scopus ID)
    Tilgjengelig fra: 2009-02-12 Laget: 2009-02-12 Sist oppdatert: 2017-12-14bibliografisk kontrollert
  • 21.
    Birgersson, Evert
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Oberstedt, Stephan
    Oberstedt, Andreas
    Örebro universitet, Institutionen för naturvetenskap.
    Hambsch, Franz-Josef
    Rochman, Dimitri
    Tsekhanovich, Igor
    Raman, Subramanian
    Light fission-fragment mass distribution from the reaction 251Cf(nth, f)2007Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 791, nr 1-2, s. 1-23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For mass numbers A = 80 to 124 the recoil mass spectrometer LOHENGRIN of the Institute Laue-Langevin in Grenoble was used to measure with high resolution the light fission-fragment mass yields and kinetic energy distributions from thermal-neutron induced fission of 252Cf* for the first time, using 251Cf as target material. The obtained mean light fragment mass AL = (107 ± 2) and the corresponding mean kinetic energy Ek,L = (103±2) MeV are within the expected trend. Emission yields around A = 115 are enhanced and the corresponding mean kinetic energy is higher compared to spontaneous fission of 252Cf. This could be explained by the existence of an additional super-deformed fission mode.

  • 22.
    Birgersson, Evert
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Oberstedt, Stephan
    Oberstedt, Andreas
    Örebro universitet, Institutionen för naturvetenskap.
    Hambsch, Franz-Josef
    Rochman, Dimitri
    Tsekhanovitsch, Igor
    Binary fission-fragment yields from the reaction 251Cf(nth, f)2005Inngår i: Nuclear fission and fission-product spectroscopy: 3rd international workshop on nuclear fission and fission-product spectroscopy, American Institute of Physics , 2005, s. 349-352Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The recoil mass spectrometer LOHENGRIN of the Laue-Langevin Institute, Grenoble has been used to measure the light fission-fragment mass yield and kinetic energy distributions from neutron-induced 252Cf*, using 251Cf as target material. ©2005 American Institute of Physics

  • 23. Björkblom, Carina
    et al.
    Olsson, Per-Erik
    Örebro universitet, Institutionen för naturvetenskap.
    Katsiadaki, I
    Wiklund, T
    Estrogen- and androgen-sensitive bioassays based on primary cell and tissue slice cultures from three-spined stickleback (Gasterosteus aculeatus)2007Inngår i: Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, ISSN 1532-0456, Vol. 146, nr 3, s. 431-442Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Endocrine disrupting compounds are chemicals that may interfere with the endocrine system causing severe effects in organisms. The three-spined stickleback (Gasterosteus aculeatus L.) offers a potential for the assessment of endocrine disruption caused by a) estrogenic xenobiotics through the estrogen-dependent protein vitellogenin and b) androgenic xenobiotics through the androgen-dependent protein spiggin. The stickleback is presently the only known fish species with a quantifiable androgen and anti-androgen biomarker endpoint. In the current study, hepatocyte and kidney primary cell cultures and liver and kidney tissue slice cultures were prepared and used for detecting estrogenic or androgenic activity in vitro through the action of hormones or municipal sewage water. The results indicate that stickleback male hepatocyte cultures are suitable in detecting estrogenic activity and stickleback female kidney tissue slice cultures in detecting androgenic activity. The tested sewage water showed high estrogenic activity but no significant androgenic activity. Primary cell and tissue slice cultures isolated from the three-spined stickleback will allow simultaneously screening in vitro for potential estrogenic and androgenic activity of complex samples.

  • 24. Borg, O. Anders
    et al.
    Eriksson, Leif A.
    Örebro universitet, Institutionen för naturvetenskap.
    Durbeej, Bo
    Electron-transfer induced repair of 6-4 photoproducts in DNA: a computational study.2007Inngår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 111, nr 12, s. 2351-2361Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanism employed by DNA photolyase to repair 6-4 photoproducts in UV-damaged DNA is explored by means of quantum chemical calculations. Considering the repair of both oxetane and azetidine lesions, it is demonstrated that reduction as well as oxidation enables a reversion reaction by creating anionic or cationic radicals that readily fragment into monomeric pyrimidines. However, on the basis of calculated reaction energies indicating that electron transfer from the enzyme to the lesion is a much more favorable process than electron transfer in the opposite direction, it is suggested that the photoenzymic repair can only occur by way of an anionic mechanism. Furthermore, it is shown that reduction of the oxetane facilitates a mechanism involving cleavage of the C−O bond followed by cleavage of the C−C bond, whereas reductive fragmentation of the azetidine may proceed with either of the intermonomeric C−N and C−C bonds cleaved as the first step. From calculations on neutral azetidine radicals, a significant increase in the free-energy barrier for the initial fragmentation step upon protonation of the carbonylic oxygens is predicted. This effect can be attributed to protonation serving to stabilize reactant complexes more than transition structures.

  • 25.
    Boström, Björn
    Örebro universitet, Institutionen för naturvetenskap.
    Achieving carbon isotope mass balance in northern forest soils, soil respiration and fungi2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Northern forests contain a large part of the global terrestrial carbon pool and it is unclear whether they will be sinks or sources for atmospheric carbon if the climate warms as predicted. Stable isotope techniques provide unique tools to study the carbon cycle at different scales but the interpretation of the isotope data is impaired by our inability to close the carbon isotope mass balance of ecosystems. This involves the paradox that the soil organic matter becomes increasingly 13C-enriched with increasing soil depth relative to the carbon input, plant litter, at the same time as soil respiration, the major carbon outflow from the soil, and fungi, organisms dependent on plant derived carbon, both are relatively 13C-enriched. I have determined the δ13C of the respired CO2 and the organic matter from different ecosystem components in a Norway spruce forest aiming at finding an explanation to the observed carbon isotope pattern.

    In the first study the soil surface respiration rate and isotopic composition was found to be governed by aboveground weather conditions the preceding 1-6 days. This suggests there is a fast flux of recent photosynthates to root respiration. In the second study I compared the respired CO2 from decomposition with the δ13C of the root free soil organic matter sampled from the litter layer down to 50 cm depth. Discrimination against 13C during respiration could not explain the 13C enrichment of soil organic matter with depth because the δ13C of the respired CO2 became increasingly 13C-enriched relative to the organic matter with soil depth. However, ~1.5‰ of the 2‰ 13C-gradient could be explained by the 13C depletion of atmospheric CO2 that has proceeded since the beginning of the 18th century due to the burning of fossil fuels and deforestation. The remaining shift was hypothesized to be due to a belowground contribution of 13C-enriched ectomycorrhizal derived carbon. In the third study I compared the δ13C of respired CO2 and sporocarps of ectomycorrhizal and saprotrophic fungi sampled in the spruce forest. The δ13C of respired CO2 and sporocarps were positively correlated and the differences in δ13C between CO2 and sporocarps were small, <±1‰ in nine out of 16 species, although three out of six species of ectomycorrhizal basidiomycetes respired 13C-enriched CO2 (up to 1.6‰), whereas three out of five species of polypores respired 13C-depleted CO2 (up to 1.7‰; P<0.05). Loss of 13C-depleted CO2 may have enriched the biomass of some fungal species in 13C. However, the consistent 13C enrichment of fungal sporocarps and respired CO2 relative to the plant materials implies that other processes must be found to explain the consistent 13C-enrichment of fungal biomass compared to plant materials. In the final study, compound specific stable isotope analyses provided further evidence for the hypothesis that the biomass of ectomycorrhizal fungi are 13C-enriched relative to host biomass because the carbon provided by the host is 13C-enriched Furthermore, ectomycorrhizal fungi showed lower average δ13C values of metabolites than saprotrophs which gives further support for the so-called saprotrophic-mycorrhizal divide. I conclude that a belowground allocation of 13C-enriched carbon to ectomycorrhizal fungi closes the carbon isotope mass balance in boreal and temperate forest soils and explains the 13C-enriched soil respiration.

    Delarbeid
    1. Forest soil respiration rate and d13C is regulated by recent above ground weather conditions
    Åpne denne publikasjonen i ny fane eller vindu >>Forest soil respiration rate and d13C is regulated by recent above ground weather conditions
    2005 (engelsk)Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 143, nr 1, s. 136-142Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Soil respiration, a key component of the global carbon cycle, is a major source of uncertainty when estimating terrestrial carbon budgets at ecosystem and higher levels. Rates of soil and root respiration are assumed to be dependent on soil temperature and soil moisture yet these factors often barely explain half the seasonal variation in soil respiration. We here found that soil moisture (range 16.5-27.6% of dry weight) and soil temperature (range 8-17.5 degrees C) together explained 55% of the variance (cross-validated explained variance; Q2) in soil respiration rate (range 1.0-3.4 micromol C m(-2) s(-1)) in a Norway spruce (Picea abies) forest. We hypothesised that this was due to that the two components of soil respiration, root respiration and decomposition, are governed by different factors. We therefore applied PLS (partial least squares regression) multivariate modelling in which we, together with below ground temperature and soil moisture, used the recent above ground air temperature and air humidity (vapour pressure deficit, VPD) conditions as x-variables. We found that air temperature and VPD data collected 1-4 days before respiration measurements explained 86% of the seasonal variation in the rate of soil respiration. The addition of soil moisture and soil temperature to the PLS-models increased the Q2 to 93%. delta13C analysis of soil respiration supported the hypotheses that there was a fast flux of photosynthates to root respiration and a dependence on recent above ground weather conditions. Taken together, our results suggest that shoot activities the preceding 1-6 days influence, to a large degree, the rate of root and soil respiration. We propose this above ground influence on soil respiration to be proportionally largest in the middle of the growing season and in situations when there is large day-to-day shifts in the above ground weather conditions. During such conditions soil temperature may not exert the major control on root respiration.

    Emneord
    Air temperature, 13C, PLS time series analysis, Root respiration, Soil temperature
    HSV kategori
    Forskningsprogram
    Miljökemi
    Identifikatorer
    urn:nbn:se:oru:diva-2966 (URN)10.1007/s00442-004-1776-z (DOI)
    Tilgjengelig fra: 2008-04-14 Laget: 2008-04-14 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    2. Isotope fractionation and 13C enrichment in soil profiles during the decomposition of soil organic matter
    Åpne denne publikasjonen i ny fane eller vindu >>Isotope fractionation and 13C enrichment in soil profiles during the decomposition of soil organic matter
    2007 (engelsk)Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 153, nr 1, s. 89-98Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The mechanisms behind the 13C enrichment of organic matter with increasing soil depth in forests are unclear. To determine if 13C discrimination during respiration could contribute to this pattern, we compared d13C signatures of respired CO2 from sieved mineral soil, litter layer and litterfall with measurements of d13C and d15N of mineral soil, litter layer, litterfall, roots and fungal mycelia sampled from a 68-year-old Norway spruce forest stand planted on previously cultivated land. Because the land was subjected to ploughing before establishment of the forest stand, shifts in d13C in the top 20 cm reflect processes that have been active since the beginning of the reforestation process. As 13C-depleted organic matter accumulated in the upper soil, a 1.0 o/oo d13C gradient from –28.5 o/oo in the litter layer to –27.6 o/oo at a depth of 2–6 cm was formed. This can be explained by the 1 o/oo drop in d13C of atmospheric CO2 since the beginning of reforestation together with the mixing of new C (forest) and old C (farmland). However, the isotopic change of the atmospheric CO2 explains only a portion of the additional 1.0& increase in d13C below a depth of 20 cm. The d13C of the respired CO2 was similar to that of the organic matter in the upper soil layers but became increasingly 13C enriched with depth, up to 2.5 o/oo relative to the organic matter. We hypothesise that this 13C enrichment of the CO2 as well as the residual increase in d13C of the organic matter below a soil depth of 20 cm results from the increased contribution of 13C-enriched microbially derived C with depth. Our results suggest that 13C discrimination during microbial respiration does not contribute to the 13C enrichment of organic matter in soils. We therefore recommend that these results should be taken into consideration when natural variations in d13C of respired CO2 are used to separate different components of soil respiration or ecosystem respiration.

    sted, utgiver, år, opplag, sider
    Berlin: Springer, 2007
    Emneord
    C:N ratio, d13C, Forest soil organic matter, Isotopic discrimination, Microbial respiration
    HSV kategori
    Forskningsprogram
    Miljökemi
    Identifikatorer
    urn:nbn:se:oru:diva-4241 (URN)10.1007/s00442-007-0700-8 (DOI)17401582 (PubMedID)
    Tilgjengelig fra: 2007-12-07 Laget: 2007-12-07 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    3. Can isotopic fractionation during respiration explain the 13C-enriched sporocarps of ectomycorrhizal and saprotrophic fungi?
    Åpne denne publikasjonen i ny fane eller vindu >>Can isotopic fractionation during respiration explain the 13C-enriched sporocarps of ectomycorrhizal and saprotrophic fungi?
    2008 (engelsk)Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 177, nr 4, s. 1012-1019Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    • The mechanism behind the 13C enrichment of fungi relative to plant materials is unclear and constrains the use of stable isotopes in studies of the carbon cycle in soils.

    • Here, we examined whether isotopic fractionation during respiration contributes to this pattern by comparing δ13C signatures of respired CO2, sporocarps and their associated plant materials, from 16 species of ectomycorrhizal or saprotrophic fungi collected in a Norway spruce forest.

    • The isotopic composition of respired CO2 and sporocarps was positively correlated. The differences in δ13C between CO2 and sporocarps were generally small, < ±1‰ in nine out of 16 species, and the average shift for all investigated species was 0.04‰. However, when fungal groups were analysed separately, three out of six species of ectomycorrhizal basidiomycetes respired 13C-enriched CO2 (up to 1.6‰), whereas three out of five species of polypores respired 13C-depleted CO2 (up to 1.7‰; P < 0.05). The CO2 and sporocarps were always 13C-enriched compared with wood, litter or roots.

    • Loss of 13C-depleted CO2 may have enriched some species in 13C. However, that the CO2 was consistently 13C-enriched compared with plant materials implies that other processes must be found to explain the consistent 13C-enrichment of fungal biomass compared with plant materials.

    sted, utgiver, år, opplag, sider
    Cambridge: Cambridge University Press, 2008
    Emneord
    Carbon/*metabolism, Carbon Dioxide/metabolism, Carbon Isotopes, Fungi/*metabolism, Nitrogen/metabolism, Nitrogen Isotopes, Oxygen Consumption/*physiology, Picea/microbiology, Time Factors, Trees/microbiology
    HSV kategori
    Forskningsprogram
    biologi
    Identifikatorer
    urn:nbn:se:oru:diva-4647 (URN)10.1111/j.1469-8137.2007.02332.x (DOI)18086229 (PubMedID)
    Tilgjengelig fra: 2008-10-20 Laget: 2008-10-20 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    4. Carbon isotope ratios in ectomycorrhizal and saprotrophic metabolites in relation to the δ13C of substrate, sporocarps and respired CO2
    Åpne denne publikasjonen i ny fane eller vindu >>Carbon isotope ratios in ectomycorrhizal and saprotrophic metabolites in relation to the δ13C of substrate, sporocarps and respired CO2
    Vise andre…
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Biologi
    Identifikatorer
    urn:nbn:se:oru:diva-15539 (URN)
    Tilgjengelig fra: 2011-05-11 Laget: 2011-05-11 Sist oppdatert: 2017-10-17bibliografisk kontrollert
  • 26.
    Boström, Björn
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Comstedt, Daniel
    Örebro universitet, Institutionen för naturvetenskap.
    Ekblad, Alf
    Örebro universitet, Institutionen för naturvetenskap.
    Can isotopic fractionation during respiration explain the 13C-enriched sporocarps of ectomycorrhizal and saprotrophic fungi?2008Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 177, nr 4, s. 1012-1019Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    • The mechanism behind the 13C enrichment of fungi relative to plant materials is unclear and constrains the use of stable isotopes in studies of the carbon cycle in soils.

    • Here, we examined whether isotopic fractionation during respiration contributes to this pattern by comparing δ13C signatures of respired CO2, sporocarps and their associated plant materials, from 16 species of ectomycorrhizal or saprotrophic fungi collected in a Norway spruce forest.

    • The isotopic composition of respired CO2 and sporocarps was positively correlated. The differences in δ13C between CO2 and sporocarps were generally small, < ±1‰ in nine out of 16 species, and the average shift for all investigated species was 0.04‰. However, when fungal groups were analysed separately, three out of six species of ectomycorrhizal basidiomycetes respired 13C-enriched CO2 (up to 1.6‰), whereas three out of five species of polypores respired 13C-depleted CO2 (up to 1.7‰; P < 0.05). The CO2 and sporocarps were always 13C-enriched compared with wood, litter or roots.

    • Loss of 13C-depleted CO2 may have enriched some species in 13C. However, that the CO2 was consistently 13C-enriched compared with plant materials implies that other processes must be found to explain the consistent 13C-enrichment of fungal biomass compared with plant materials.

  • 27.
    Boström, Björn
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Comstedt, Daniel
    Örebro universitet, Institutionen för naturvetenskap.
    Ekblad, Alf
    Örebro universitet, Institutionen för naturvetenskap.
    Isotope fractionation and 13C enrichment in soil profiles during the decomposition of soil organic matter2007Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 153, nr 1, s. 89-98Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanisms behind the 13C enrichment of organic matter with increasing soil depth in forests are unclear. To determine if 13C discrimination during respiration could contribute to this pattern, we compared d13C signatures of respired CO2 from sieved mineral soil, litter layer and litterfall with measurements of d13C and d15N of mineral soil, litter layer, litterfall, roots and fungal mycelia sampled from a 68-year-old Norway spruce forest stand planted on previously cultivated land. Because the land was subjected to ploughing before establishment of the forest stand, shifts in d13C in the top 20 cm reflect processes that have been active since the beginning of the reforestation process. As 13C-depleted organic matter accumulated in the upper soil, a 1.0 o/oo d13C gradient from –28.5 o/oo in the litter layer to –27.6 o/oo at a depth of 2–6 cm was formed. This can be explained by the 1 o/oo drop in d13C of atmospheric CO2 since the beginning of reforestation together with the mixing of new C (forest) and old C (farmland). However, the isotopic change of the atmospheric CO2 explains only a portion of the additional 1.0& increase in d13C below a depth of 20 cm. The d13C of the respired CO2 was similar to that of the organic matter in the upper soil layers but became increasingly 13C enriched with depth, up to 2.5 o/oo relative to the organic matter. We hypothesise that this 13C enrichment of the CO2 as well as the residual increase in d13C of the organic matter below a soil depth of 20 cm results from the increased contribution of 13C-enriched microbially derived C with depth. Our results suggest that 13C discrimination during microbial respiration does not contribute to the 13C enrichment of organic matter in soils. We therefore recommend that these results should be taken into consideration when natural variations in d13C of respired CO2 are used to separate different components of soil respiration or ecosystem respiration.

  • 28.
    Boström, Björn
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Ekblad, Alf
    Örebro universitet, Institutionen för naturvetenskap.
    Gleixner, Gerd
    Hettmann, Elena
    Volders, Filip
    Carbon isotope ratios in ectomycorrhizal and saprotrophic metabolites in relation to the δ13C of substrate, sporocarps and respired CO2 Manuskript (preprint) (Annet vitenskapelig)
  • 29. Brosché, Mikael
    et al.
    Gittins, John R.
    Sävenstrand, Helena
    Örebro universitet, Institutionen för naturvetenskap.
    Strid, Åke
    Örebro universitet, Institutionen för naturvetenskap.
    Gene expression under environmental stresses: molecular marker analysis2002Inngår i: Molecular techniques in crop improvement / [ed] S. Mohan Jain, D.S. Brar, B.S. Ahloowalia, Boston: Kluwer Academic Publishers, 2002, s. 371-408Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 30. Brosché, Mikael
    et al.
    Schuler, Mary A.
    Kalbina, Irina
    Örebro universitet, Institutionen för naturvetenskap.
    Connor, Lynn
    Strid, Åke
    Örebro universitet, Institutionen för naturvetenskap.
    Gene regulation by low level UV-B radiation: identification by DNA array analysis2002Inngår i: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 1, nr 9, s. 656-664Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    UV-B radiation alters transcript levels of various defence genes and photosynthetic genes in plants. Utilising a DNA array with 5000 ESTs and cDNAs from Arabidopsis thaliana, 70 genes were found to show a greater than two-fold induction or repression of transcript levels. Six genes (MEB5.2, PyroA, Ubq3, Lhcb6, F5D21.10 and the gene for an RNA polymerase II subunit) were tested for stress specific gene regulation on northern blots with RNA from plants exposed to low dose UV-B radiation, ozone or wounding. Transcript levels for PyroA, Uhq3 and the gene for a RNA polymerase II subunit were all specifically increased by UV-B. MEB5.2 mRNA levels also rose, whereas Lhcb6 and FSD21.10 transcript levels decreased under all stresses. The PyroA gene product in fungi is needed for biosynthesis of pyridoxine, and might have a role in protection against singlet oxygen. The Ubq3 gene encodes the ubiquitin protein that is attached to proteins destined for degradation. MEB5.2 and F5D21.10 represent novel gene products whose function have not yet been identified. Pairwise comparisons between the UV-B inducible promoters have identified a series of elements present in the MEB5.2 and PyroA promoters, absent from promoters of genes for early phenylpropanoid metabolism and that may be responsible for modulating their UV-B responses.

  • 31. Brosché, Mikael
    et al.
    Strid, Åke
    Örebro universitet, Institutionen för naturvetenskap.
    Molecular events following perception of ultraviolet-B radiation by plants2003Inngår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 117, nr 1, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exposure of plants to UV-B radiation (280–320 nm) results in changes in expression of a large number of genes. Before UV-B radiation or light of other wavelengths can give rise to a cellular response, it has to be perceived by some kind of receptor, and the information transduced via a signalling pathway to the target molecules, be it proteins in the cytoplasm

    or the genetic material in the nucleus. The perception of low levels of UV-B probably occurs via a UV-B photoreceptor followed by several different signalling pathways. These pathways include second messengers such as calcium, kinases and the catalytic formation of reactive oxygen species. High levels of UV-B, on the other hand, probably cause cellular damage

    and oxidative stress, thus activating a general stress signal transduction pathway which leads to a response similar to that which occurs after pathogen attack and other stresses. Some of the genes identified so far as being regulated by UV-B encode proteins involved in the biosynthesis of protective pigments, DNA repair and antioxidative enzymes, photosynthetic genes, cell cycle genes, and stress genes induced by other types of stimuli (i.e. pathogenesis-related proteins and senescence-induced genes). In the light of the information obtained on components necessary for UV-B-induced changes in gene expression, we propose in this mini-review a working model for UV-B perception and signal transduction. This model also takes into account dosage differences for the observations, which imply a separation into UV-B-specific and more general stress signal transduction.

  • 32. Buffam, Ishi
    et al.
    Laudon, Hjalmar
    Temnerud, Johan
    Örebro universitet, Institutionen för naturvetenskap.
    Morth, Carl-Magnus
    Bishop, Kevin
    Landscape-scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network2007Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 112, nr G1, s. G01022-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Acidity is well known to influence stream biota, but the less well-studied spatial and temporal distributions of acidity are likely to play a larger ecological role than average values. We present data on spatial variability of chemical parameters contributing to acidity during winter baseflow and spring flood periods in Krycklan, a fourth-order boreal stream network in northern Sweden. Fifteen stream sites were monitored in subcatchments spanning 3 orders of magnitude in size and representing a wide range of percent wetland. At baseflow, pH ranged from 3.9 to 6.5 at the different sites. Baseflow dissolved organic carbon (DOC) concentration varied by an order of magnitude and was positively correlated with subcatchment percent wetland, resulting in high spatial variability in dissociated organic acids (OA(-)). During spring flood, DOC and OA(-) increased in forested sites and decreased in wetland sites, resulting in reduced spatial variability in their concentrations. In contrast, base cations and strong acid anions diluted throughout the stream network, resulting in decreased acid neutralizing capacity (ANC) at all sites. The spatial variability of base cations increased slightly with high flow. As a result of the changes in OA(-) and ANC, pH dropped at all but the most acidic site, giving a slightly narrowed pH range during spring flood (4.2-6.1). The transition from winter to spring flood stream chemistry could largely be explained by: (1) a shift from mineral to upper riparian organic soil flow paths in forested catchments and (2) dilution of peat water with snowmelt in wetland catchments.

  • 33. Bunta, Juraj
    et al.
    Dahlberg, Martin
    Eriksson, Leif A.
    Örebro universitet, Institutionen för naturvetenskap.
    Korolev, Nikolai
    Laaksonen, Aatto
    Lohikoski, Raimo
    Lyubartsev, Alexander
    Pinak, Miroslav
    Schyman, Patric
    Solvating, manipulating, damaging, and repairing DNA in a computer2007Inngår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 107, nr 2, s. 279-291Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work highlights four different topics in modeling of DNA: (i) the importance of water and ions together with the structure and function of DNA; the hydration structure around the ions appears to be the determining factor in the ion coordination to DNA, as demonstrated in the results of our MD simulations; (ii) how MD simulations can be used to simulate single molecule manipulation experiments as a complement to reveal the structural dynamics of the studied biomolecules; (iii) how damaged DNA can be studied in computer simulations; and (iv) how repair of damaged DNA can be studied theoretically.

  • 34.
    Bäckström, Mattias
    Örebro universitet, Institutionen för naturvetenskap.
    On the chemical state and mobility of lead and other trace elements at the biogeosphere/technosphere interface2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Most inorganic contamination has occurred at the interface between the technosphere and the biogeosphere, even though atmospheric emissions have affected the entire globe. Several human activities now pose a substantial threat towards human health and the ecosystems. It was thus decided to study lead as an element with significant anthropogenic emissions in a variety of sources and environments. Lead and other trace elements were studied in groundwaters used for drinking water, in roadside environments, at a shooting range and in a contaminated lake in order to obtain information about mobility and redistribution in different hydrobiogeochemical environments.

    It was found that 60% of the investigated drilled wells in crystalline bedrock failed to meet international health safety limits. This was mainly due to the presence of enhanced concentrations of fluoride and uranium.

    Along roads the concentrations and massfluxes increased significantly for lead, as well as for otheer elements during the winter. This is most likely due to increased pavement wear as a consequence of studded tires and use of deicing salts. The mobility of trace elements also increased in the roadside soils, threatening the shallow groundwater.

    At the shooting range it was found that the downward migration of lead was greater than expected and equilibrium with cerussite was suggested from solid speciation and geochemical calculations. Antimony was associated with lead and showed, despite differences in chemical properties, a similar distribution pattern. This was due to the fact that the major part of the transport at the shooting range was physical.

    In the contaminated lake, several findings regarding the solid speciation of lead was confirmed and other information about redistribution into the hypolimnion from the sediment was gained.

    Delarbeid
    1. Chemical character of drinking water from Swedish crystaline bedrock
    Åpne denne publikasjonen i ny fane eller vindu >>Chemical character of drinking water from Swedish crystaline bedrock
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Kemi
    Identifikatorer
    urn:nbn:se:oru:diva-15924 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2017-10-17bibliografisk kontrollert
    2. Speciation of heavy metals in road runoff and roadside total deposition
    Åpne denne publikasjonen i ny fane eller vindu >>Speciation of heavy metals in road runoff and roadside total deposition
    Vise andre…
    2003 (engelsk)Inngår i: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 147, nr 1-4, s. 343-366Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The concentrations of Cd, Co, Cu, Pb, W and Zn were measured in road runoff and total deposition at two Swedish field sites during one year. It was found that the concentrations of most elements increased significantly during the winter, up to one order of magnitude. For cobalt and tungsten, it was found that around 90% of the total mass transport occurred during the winter, whereas for Cu, Pb, Cd, Zn and Na, the corresponding figures were 70–90, 40–80, 60–90, 50–70 and >99% depending on site specific conditions. The deicing salts (rock salts) did not significantly contribute to the increase in trace element concentrations. Instead, the increased concentrations were due to more intense wearing of the pavement during the winter because of the use of studded tires in combination with the chemical effects caused by the use of deicing salts. New potential elemental markers for roads and traffic are suggested.

    HSV kategori
    Forskningsprogram
    Miljövetenskap
    Identifikatorer
    urn:nbn:se:oru:diva-5196 (URN)10.1023/A:1024545916834 (DOI)
    Tilgjengelig fra: 2009-01-30 Laget: 2009-01-30 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    3. Mobilisation of heavy metals by deicing salts in a roadside environment
    Åpne denne publikasjonen i ny fane eller vindu >>Mobilisation of heavy metals by deicing salts in a roadside environment
    Vise andre…
    2004 (engelsk)Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 38, nr 3, s. 720-732Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The seasonal variations of some selected heavy metals (Cd, Cu, Pb and Zn) and principal anions in soil solutions were monitored as a function of distance from the road at two field sites in Sweden. During the winter, the conductivity, concentrations of dissolved sodium and chloride increased dramatically due to the application of deicing agents (i.e. NaCl). Due to ion exchange, the pH decreased one unit in the soil solutions, whereas the concentrations of total organic carbon decreased due to coagulation and/or sorption to stationary solids. The heavy metal concentrations increased during the winter, but through different mechanisms. Cadmium concentrations in the aqueous phase increased as a response to ion exchange, possibly also enhanced by the formation of chloride complexes. Similarly, the concentrations of zinc increased, due to ion exchange, with calcium and protons. The mechanisms of mobilisation for copper and lead were not that clear probably due to association with coagulated or sorbed organic matter in combination with colloid dispersion

    HSV kategori
    Forskningsprogram
    Miljövetenskap
    Identifikatorer
    urn:nbn:se:oru:diva-5200 (URN)10.1016/j.watres.2003.11.006 (DOI)
    Tilgjengelig fra: 2009-01-30 Laget: 2009-01-30 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    4. Metal leachability and anthropogenic signal in roadside soils estimated from sequential extraction and stable lead isotopes
    Åpne denne publikasjonen i ny fane eller vindu >>Metal leachability and anthropogenic signal in roadside soils estimated from sequential extraction and stable lead isotopes
    2004 (engelsk)Inngår i: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 90, nr 1-3, s. 135-160Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Several roadside soil samples were collected at two field sites in Sweden. They were analysed for total elemental content (using both ICP-MS and XRF) and stable lead isotopes. Extraction with deicing salt solution and sequential extraction were performed in order to elucidate the potential mobility due to the use of deicing agents. The total concentrations of elements, especially lead, have decreased and lead is presently almost at background concentrations (15–51 ppm for surface samples). However, the isotopic signature indicates that old gasoline lead still is left at the site constructed prior to 1975. The field site constructed in 1992 showed, however, no 206Pb/207Pb ratio below 1.14. Only minor amounts were leached using deicing salt solutions; for lead only 0.29%, on average, was extracted indicating that the mobile fraction already was released. Sequential extraction indicated that lead mainly was associated with reducible (34.4%) and oxidisable (35.4%) fractions. Exchangable and acid soluble fractions contained 20.3% while 10.0% was found in the residual fraction. The salt extraction released, however, very low concentrations indicating that most in fraction 1 is acid soluble (e.g. carbonates). Tungsten was also found at high concentrations indicating a possible impact from studded tires. For tungsten the following composition was obtained: residual (48.0%) > oxidisable (47.6%) > reducible (3.3%) > exchangeable/acid soluble (1.1%). From the isotopic studies it was also suggested that the order for incorporating anthropogenic lead into soils is exchangeable/carbonates > (hydr)oxides > organic matter > residual. The multivariate technique principal component analysis (PCA) seems promising for evaluating large sequential extraction datasets.

    HSV kategori
    Forskningsprogram
    Kemi
    Identifikatorer
    urn:nbn:se:oru:diva-5197 (URN)10.1023/B:EMAS.0000003572.40515.31 (DOI)
    Tilgjengelig fra: 2009-01-30 Laget: 2009-01-30 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    5. Factors affecting the dissolution of lead pellets in natural waters
    Åpne denne publikasjonen i ny fane eller vindu >>Factors affecting the dissolution of lead pellets in natural waters
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Kemi
    Identifikatorer
    urn:nbn:se:oru:diva-15925 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2017-10-17bibliografisk kontrollert
    6. Multielement contamination at a skeet and trap shooting range: I: mobility assessment through sequential extraction
    Åpne denne publikasjonen i ny fane eller vindu >>Multielement contamination at a skeet and trap shooting range: I: mobility assessment through sequential extraction
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Kemi
    Identifikatorer
    urn:nbn:se:oru:diva-15926 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2017-10-17bibliografisk kontrollert
    7. Multielement contamination at a skeet and trap shooting range: II: seasonal and spatial variations in surface and groundwaters
    Åpne denne publikasjonen i ny fane eller vindu >>Multielement contamination at a skeet and trap shooting range: II: seasonal and spatial variations in surface and groundwaters
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Kemi
    Identifikatorer
    urn:nbn:se:oru:diva-15928 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2019-03-26bibliografisk kontrollert
    8. Migration and mobility of lead and antimony from a heavily polluted lake sediment
    Åpne denne publikasjonen i ny fane eller vindu >>Migration and mobility of lead and antimony from a heavily polluted lake sediment
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Kemi
    Identifikatorer
    urn:nbn:se:oru:diva-15929 (URN)
    Tilgjengelig fra: 2011-06-15 Laget: 2011-06-15 Sist oppdatert: 2017-10-17bibliografisk kontrollert
  • 35.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Bohlin, Hanna
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Holm, Nils
    Element (Ag, Cd, Cu, Pb, Sb, Tl and Zn), element ratio and lead isotope profiles in a sediment affected by a mining operation episode during the late 19th century2006Inngår i: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 177, nr 1-4, s. 285-311Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mining operations at Maarsaetter in 1877-81 resulted in increased metal loading to a small lake, notably as sulphidic tailings. The event is taken as an opportunity to study the present environmental impact of a historical single major metal release. Lake water and four sediment cores were sampled and analysed for principal and trace elements in solid and aqueous phases as well as general hydrochemical conditions. Chronologies were determined from super(206)Pb/ super(207)Pb ratios and historical records.Ordinary sedimentation after the event has lead to that the tailings are found as a distinct layer at a depth of 18-22 cm in the sediment. The layer is characterized by elevated metal concentrations in the solid and pore water phases, respectively, circum neutral pH and sulphate concentrations below detection. Geochemical modelling indicated a preference for carbonate equilibrium in the waste while sulphides prevailed above it. It is concluded that the growth of the ordinary sediment on top of the waste has lead to a physicochemical barrier that seals of the waste from the overlying sediment. Chemical or physical rupture of the barrier will release the metals to downstream regions.According to the chronologies at least three sources have contributed to the present elevated levels of metals, in additions to the release of tailings. Copper from a historical blast furnace prior to the event at Maarsaetter, transport from mineralized parts of the watershed and release of contaminated water from present mining operations maintain elevated levels of notably zinc, silver, cadmium and lead. At present less than 10% of the lead content at the sediment/water interface comes from atmospheric deposition. Increased levels of antimony and thallium were not observed prior to ca 1950.

  • 36.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Börjesson, Erika
    SWECO VBB VIAK, SE-61132 Nykoping, Sweden.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Diurnal variations of abiotic parameters in a stream, recipient for drainage water in Ranstad, southwest Sweden2002Inngår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 4, nr 5, s. 772-777Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During 24 h, water samples were taken for determination of a number of key parameters in a water system containing high concentrations of FeII at circumneutral pH. None of the major constituents (Ca, Mg, Na, K and sulfate) showed diurnal variations, while dissolved oxygen and pH increased during the night. This increase could entirely be explained by the decrease in water temperature. However, the concentration of FeII slightly increased at constant concentration of total Fe during the night, opposite to earlier observations in other systems where the presence of FeII was shown to be controlled by photoreduction. Nocturnal peaks of FeII have also been observed in other systems with high iron concentrations, however, at acidic pH, but without obvious explanation. The mechanisms for this process therefore need further investigation.

  • 37.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Dario, Mårten
    Örebro universitet, Institutionen för naturvetenskap.
    Allard, Bert
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Effects of a fulvic acid on the adsorption of mercury and cadmium on goethite2003Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 304, nr 1-3, s. 257-268Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of an aquatic fulvic acid on the pH-dependent adsorption of Hg(II) and Cd(II) to particulate goethite (a-FeOOH) were studied in batch systems. The ionic medium consisted of 0.01 M HClO and the total concentrations 4 of mercury and cadmium were maintained at 10y8 M with 203Hg and 109Cd as tracers. pH In the systems was varied in the range 3–10 by addition of HClO and NaOH.All commercial chemicals were of analytical grade or better. An 4 aquatic fulvic acid (20 ppm), previously isolated and characterised in detail, was used as a model for humic substances and its adsorption to goethite is included in this study. The adsorption of the fulvic acid (20 ppm) onto goethite decreased slowly from 90% at pH 3–7.5 to 10% at pH 10. In systems without fulvic acid the adsorption of mercury increased in a linear fashion from 10% at pH 3 to 70% at pH 10.In the presence of fulvic acid (20 ppm), the adsorption was almost quantitative in the intermediate pH range (pH 5–7), and exceeded 92% over the entire pH range. Thus, association between mercury and the fulvic acid enhanced adsorption in general although the largest impact was found at low pH.Adsorption of cadmium increased from nearly 0 to almost 100% at approximately pH 6. In the presence of fulvic acid, the adsorption increased below pH 7 and decreased above pH 7. The adsorption isotherm for mercury when the concentration was increased from 10y8 to 1.8=10y4 M showed a corresponding increase of K (lyg) up to a total concentration at 10y6 M.At higher mercury concentrations K was lowered. In the presence of fulvic acid the corresponding relationship of K was bi-modal, i.e. high values at low and intermediate concentrations of mercury. This behaviour suggests that in the absence of fulvic acid the adsorption follow the expected behaviour, i.e. adsorption sites with similar affinity for mercury. In the presence of fulvic acid, additional adsorption sites are available by the organic molecule (possibly sulfur groups) when it is associated to the goethite. The adsorption isotherm for cadmium indicates a lowering of K at 10y4 M. Cadmium had no competitive effect on mercury and vice versa. Zinc, however, affected the adsorption of cadmium but not the adsorption of mercury.

  • 38. Bäckström, Mattias
    et al.
    Dario, Mårten
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Allard, Bert
    Örebro universitet, Institutionen för naturvetenskap.
    Effects of a fulvic acid on the adsorption of mercury and cadmium on goethite2003Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 304, nr 1-3, s. 257-268Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of an aquatic fulvic acid on the pH-dependent adsorption of Hg(II) and Cd(II) to particulate goethite (alpha-FeOOH) were studied in batch systems. The ionic medium consisted of 0.01 M HClO(4) and the total concentrations of mercury and cadmium were maintained at 10(-8) M with 203Hg and 109Cd as tracers. pH In the systems was varied in the range 3-10 by addition of HClO(4) and NaOH. All commercial chemicals were of analytical grade or better. An aquatic fulvic acid (20 ppm), previously isolated and characterised in detail, was used as a model for humic substances and its adsorption to goethite is included in this study. The adsorption of the fulvic acid (20 ppm) onto goethite decreased slowly from 90% at pH 3-7.5 to 10% at pH 10. In systems without fulvic acid the adsorption of mercury increased in a linear fashion from 10% at pH 3 to 70% at pH 10. In the presence of fulvic acid (20 ppm), the adsorption was almost quantitative in the intermediate pH range (pH 5-7), and exceeded 92% over the entire pH range. Thus, association between mercury and the fulvic acid enhanced adsorption in general although the largest impact was found at low pH. Adsorption of cadmium increased from nearly 0 to almost 100% at approximately pH 6. In the presence of fulvic acid, the adsorption increased below pH 7 and decreased above pH 7. The adsorption isotherm for mercury when the concentration was increased from 10(-8) to 1.8 x 10(-4) M showed a corresponding increase of K(d) (l/g) up to a total concentration at 10(-6) M. At higher mercury concentrations K(d) was lowered. In the presence of fulvic acid the corresponding relationship of K(d) was bi-modal, i.e. high values at low and intermediate concentrations of mercury. This behaviour suggests that in the absence of fulvic acid the adsorption follow the expected behaviour, i.e. adsorption sites with similar affinity for mercury. In the presence of fulvic acid, additional adsorption sites are available by the organic molecule (possibly sulfur groups) when it is associated to the goethite. The adsorption isotherm for cadmium indicates a lowering of K(d) at 10(-4) M. Cadmium had no competitive effect on mercury and vice versa. Zinc, however, affected the adsorption of cadmium but not the adsorption of mercury.

  • 39.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Multielement contamination at a skeet and trap shooting range: I: mobility assessment through sequential extractionManuskript (preprint) (Annet vitenskapelig)
  • 40.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Allard, Bert
    Örebro universitet, Institutionen för naturvetenskap.
    Metal leachability and anthropogenic signal in roadside soils estimated from sequential extraction and stable lead isotopes2004Inngår i: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 90, nr 1-3, s. 135-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several roadside soil samples were collected at two field sites in Sweden. They were analysed for total elemental content (using both ICP-MS and XRF) and stable lead isotopes. Extraction with deicing salt solution and sequential extraction were performed in order to elucidate the potential mobility due to the use of deicing agents. The total concentrations of elements, especially lead, have decreased and lead is presently almost at background concentrations (15–51 ppm for surface samples). However, the isotopic signature indicates that old gasoline lead still is left at the site constructed prior to 1975. The field site constructed in 1992 showed, however, no 206Pb/207Pb ratio below 1.14. Only minor amounts were leached using deicing salt solutions; for lead only 0.29%, on average, was extracted indicating that the mobile fraction already was released. Sequential extraction indicated that lead mainly was associated with reducible (34.4%) and oxidisable (35.4%) fractions. Exchangable and acid soluble fractions contained 20.3% while 10.0% was found in the residual fraction. The salt extraction released, however, very low concentrations indicating that most in fraction 1 is acid soluble (e.g. carbonates). Tungsten was also found at high concentrations indicating a possible impact from studded tires. For tungsten the following composition was obtained: residual (48.0%) > oxidisable (47.6%) > reducible (3.3%) > exchangeable/acid soluble (1.1%). From the isotopic studies it was also suggested that the order for incorporating anthropogenic lead into soils is exchangeable/carbonates > (hydr)oxides > organic matter > residual. The multivariate technique principal component analysis (PCA) seems promising for evaluating large sequential extraction datasets.

  • 41.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Allard, Bert
    Örebro universitet, Institutionen för naturvetenskap.
    Mobilisation of lead: field measurements at a trap range compared to solubility experiments2000Konferansepaper (Fagfellevurdert)
  • 42.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Bäckman, Lars
    Folkeson, Lennart
    Lind, Bo
    Mobilisation of heavy metals by deicing salts in a roadside environment2004Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 38, nr 3, s. 720-732Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The seasonal variations of some selected heavy metals (Cd, Cu, Pb and Zn) and principal anions in soil solutions were monitored as a function of distance from the road at two field sites in Sweden. During the winter, the conductivity, concentrations of dissolved sodium and chloride increased dramatically due to the application of deicing agents (i.e. NaCl). Due to ion exchange, the pH decreased one unit in the soil solutions, whereas the concentrations of total organic carbon decreased due to coagulation and/or sorption to stationary solids. The heavy metal concentrations increased during the winter, but through different mechanisms. Cadmium concentrations in the aqueous phase increased as a response to ion exchange, possibly also enhanced by the formation of chloride complexes. Similarly, the concentrations of zinc increased, due to ion exchange, with calcium and protons. The mechanisms of mobilisation for copper and lead were not that clear probably due to association with coagulated or sorbed organic matter in combination with colloid dispersion

  • 43.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Lifvergren, Thomas
    Estimation of molecular weight distributions of humic substances in sediment pore waters: PLS modelling of field data2001Inngår i: 8th Nordic IHSS symposium on humic substances: characterisation, dynamics, transport and effects, Copenhagen: Royal Veterinary and Agricultural University , 2001, s. 17-21Konferansepaper (Fagfellevurdert)
  • 44.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Mellberg, Karin
    Factors affecting the dissolution of lead pellets in natural watersManuskript (preprint) (Annet vitenskapelig)
  • 45.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Salih, Isam
    Pettersson, Håkan
    Chemical character of drinking water from Swedish crystaline bedrockManuskript (preprint) (Annet vitenskapelig)
  • 46.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Ulrika
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Hydrogeochemical interpretations of a fly ash/municipal sludge covered sulphidic mine waste deposit: a case study of alkaline leachates in an acidic environmentManuskript (Annet vitenskapelig)
  • 47.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Lifvergren, Thomas
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Migration and mobility of lead and antimony from a heavily polluted lake sedimentManuskript (preprint) (Annet vitenskapelig)
  • 48.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Nilsson, Ulrika
    Håkansson, Karsten
    Allard, Bert
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Speciation of heavy metals in road runoff and roadside total deposition2003Inngår i: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 147, nr 1-4, s. 343-366Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concentrations of Cd, Co, Cu, Pb, W and Zn were measured in road runoff and total deposition at two Swedish field sites during one year. It was found that the concentrations of most elements increased significantly during the winter, up to one order of magnitude. For cobalt and tungsten, it was found that around 90% of the total mass transport occurred during the winter, whereas for Cu, Pb, Cd, Zn and Na, the corresponding figures were 70–90, 40–80, 60–90, 50–70 and >99% depending on site specific conditions. The deicing salts (rock salts) did not significantly contribute to the increase in trace element concentrations. Instead, the increased concentrations were due to more intense wearing of the pavement during the winter because of the use of studded tires in combination with the chemical effects caused by the use of deicing salts. New potential elemental markers for roads and traffic are suggested.

  • 49.
    Bäckström, Mattias
    et al.
    Örebro universitet, Institutionen för naturvetenskap.
    Sartz, Lotta
    Örebro universitet, Institutionen för naturvetenskap.
    Karlsson, Stefan
    Örebro universitet, Institutionen för naturvetenskap.
    Multielement contamination at a skeet and trap shooting range: II: seasonal and spatial variations in surface and groundwatersManuskript (preprint) (Annet vitenskapelig)
  • 50. Carlson, Allan
    et al.
    Sandström, Ulf
    Örebro universitet, Institutionen för naturvetenskap.
    Olsson, Karin
    Availability and use of natural tree holes by cavity nesting birds in a Swedish deciduous forest1998Inngår i: Ardea, ISSN 0373-2266, E-ISSN 2213-1175, Vol. 86, nr 1, s. 109-119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cavities in trees are an important resource as nest sites or shelter for many birds and mammals. The aim of this study was to quantify the density of cavities, their characteristics, and their origin, and the implication these have on nest site choice by hole-nesting birds. The study was carried out in a deciduous forest in south central Sweden during two years. The forest was dominated by Pendunculate Oak Quercus robur, Norway Maple Acer plantanoides, Small-leaved Lime Tilia cordata, Rowan Sorbus aucuparia, birch Betula pubescens/verrucosa and Aspen Populus tremula, in decreasing order of abundance. We found an average cavity density of 60.4 ha-1. Limb holes were the most abundant type found (53%) and were also most frequently used by hole-nesting birds (64.8%). Pendunculate Oak and Aspen were the two tree species richest in cavities. Limb holes dominated in Pendunculate Oak while woodpecker-excavated holes dominated in aspen. Cavities with occupied bird nests had narrower entrances, were located higher up, had smaller volumes, thicker walls and a smaller circumference of the stem at the hole compared with unoccupied cavities. Limb holes, woodpecker holes and other hole types were used as nest sites by birds in proportion to their frequency of occurrence in the forest. Each year only 5-10% of available cavities attracted breeding birds. The most salient features that emerge from these results are the high density of cavities and their low occupancy rate.

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