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  • 51.
    Comstedt, Daniel
    Örebro University, Department of Natural Sciences.
    Explaining temporal variations in soil respiration rates and delta13C in coniferous forest ecosystems2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, 13C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ13C, and above and below ground abiotic conditions. In both forests, variation in δ13C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ13C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ13C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ13C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ13C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.

    List of papers
    1. Effects of elevated atmospheric carbon dioxide and temperature on soil respiration in a boreal forest using δ13C as a labeling tool
    Open this publication in new window or tab >>Effects of elevated atmospheric carbon dioxide and temperature on soil respiration in a boreal forest using δ13C as a labeling tool
    Show others...
    2006 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 9, no 8, p. 1266-1277Article in journal (Refereed) Published
    National Category
    Environmental Sciences Natural Sciences Chemical Sciences
    Research subject
    Environmental Chemistry
    Identifiers
    urn:nbn:se:oru:diva-2965 (URN)10.1007/s10021-006-0110-5 (DOI)
    Note

    Part of thesis: http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-2055

    Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2017-12-14Bibliographically approved
    2. Forest soil respiration rate and d13C is regulated by recent above ground weather conditions
    Open this publication in new window or tab >>Forest soil respiration rate and d13C is regulated by recent above ground weather conditions
    2005 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 143, no 1, p. 136-142Article in journal (Refereed) 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.

    Keywords
    Air temperature, 13C, PLS time series analysis, Root respiration, Soil temperature
    National Category
    Biomaterials Science Chemical Sciences Environmental Sciences
    Research subject
    Environmental Chemistry
    Identifiers
    urn:nbn:se:oru:diva-2966 (URN)10.1007/s00442-004-1776-z (DOI)
    Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2017-12-14Bibliographically approved
    3. A link between above ground weather conditions and the δ13C of forest soil respiration is not always observed
    Open this publication in new window or tab >>A link between above ground weather conditions and the δ13C of forest soil respiration is not always observed
    (English)Manuscript (Other academic)
    National Category
    Natural Sciences Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-2967 (URN)
    Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2017-10-18Bibliographically approved
    4. Autotrophic and heterotrophic soil respiration in a Norway spruce forest: estimating the root decomposition and soil moisture effects in a trenching experiment
    Open this publication in new window or tab >>Autotrophic and heterotrophic soil respiration in a Norway spruce forest: estimating the root decomposition and soil moisture effects in a trenching experiment
    (English)Manuscript (Other academic)
    National Category
    Natural Sciences Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-2968 (URN)
    Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2017-10-18Bibliographically approved
  • 52.
    Comstedt, Daniel
    et al.
    Örebro University, Department of Natural Sciences.
    Boström, Björn
    Örebro University, Department of Natural Sciences.
    Ekblad, Alf
    Örebro University, Department of Natural Sciences.
    Autotrophic and heterotrophic soil respiration in a Norway spruce forest: estimating the root decomposition and soil moisture effects in a trenching experimentManuscript (Other academic)
  • 53.
    Comstedt, Daniel
    et al.
    Örebro University, Department of Natural Sciences.
    Boström, Björn
    Marshall, John
    Holm, Anders
    Slaney, Michelle
    Linder, Sune
    Ekblad, Alf
    Effects of elevated atmospheric carbon dioxide and temperature on soil respiration in a boreal forest using δ13C as a labeling tool2006In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 9, no 8, p. 1266-1277Article in journal (Refereed)
  • 54.
    Comstedt, Daniel
    et al.
    Örebro University, Department of Natural Sciences.
    Boström, Björn
    Thompson, Matthew V.
    Ekblad, Alf
    A link between above ground weather conditions and the δ13C of forest soil respiration is not always observedManuscript (Other academic)
  • 55. Covaci, Adrian
    et al.
    Voorspoels, Stefan
    Thomsen, Cathrine
    van Bavel, Bert
    Örebro University, Department of Natural Sciences.
    Neels, Hugo
    Evaluation of total lipids using enzymatic methods for the normalization of persistent organic pollutant levels in serum2006In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 366, no 1, p. 361-366Article in journal (Refereed)
    Abstract [en]

    The human exposure to persistent organic pollutants (POPs) is conveniently assessed through analysis of blood serum or plasma and the POPs concentrations are traditionally expressed on a lipid weight basis. Enzymatic determinations of total lipid (TL) content in serum, which imply the measurement of individual lipid classes, such as triglycerides (TG), cholesterol (CHOL) and phospholipid (PL), use small amounts of serum/plasma (<100 microl). These have also become a more precise and less laborious alternative for the gravimetric lipid determinations which were preferred in the past. However, PL are not routinely measured in most clinical laboratories and therefore, TL values are often predicted from formulas based on measurements of only TG and CHOL. In the present study, a large data set (n=483) from Belgian, Swedish and Norwegian populations was used to compute a new formula for TL [TL=1.33*TG+1.12*CHOL+1.48 (g/l)] by means of multiple linear regression. A very good correlation (r=0.949, p<0.001) was found between TL values calculated with the proposed formula and TL values obtained by summation of TG, CHOL and PL. Statistically different values of TL were computed when different previously published formulas were compared, which can have a strong influence on the calculation of lipid-normalized concentrations of POPs. Nevertheless, TL values derived using a mathematical formula which includes only TG and CHOL will be less accurate than TL values obtained by summation of TG, CHOL and PL, which should be the calculation method of choice if PL measurements are available.

  • 56. Dahlén, Johan
    et al.
    Bäckström, Mattias
    Örebro University, Department of Natural Sciences.
    Ephraim, James
    Borén, Hans
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Determination of the molecular weight of fulvic acids by UV/VIS spectroscopy1999In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 38, no 4, p. 783-794Article in journal (Refereed)
    Abstract [en]

    Partial least squares (PLS) modeling was applied to investigate number-average molecular weights (Mn) and weight-average molecular weights (Mw) of fulvic acids (FAs) in relation to the corresponding UVNIS spectra. The Mn and Mw values were determined by size exclusion chromatography (SEC). The impact of pH control, wavelength range and density as well as smoothing and derivation of spectra were tested. It was found that PLS models based on absorbance spectra can be a fast and powerful complement to existing techniques employed for determination of molecular weights of FAs. Control of pH of the FA solutions is important for the performance of the models. The models were also compared with the best univariate alternatives.

  • 57. Dahlén, Johan
    et al.
    Hagberg, Jessika
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Analysis of low molecular weight organic acids in water with capillary zone electrophoresis employing indirect photometric detection2000In: Fresenius' Journal of Analytical Chemistry, ISSN 0937-0633, E-ISSN 1432-1130, Vol. 366, no 5, p. 488-493Article in journal (Refereed)
    Abstract [en]

    A capillary zone electrophoretic method for the analysis of low molecular weight carboxylic acids in water was developed. The application uses the chromophore trimellitic acid that allows for indirect photometric detection at 254 nm. Selectivity control by the addition of Ca2+ to the carrier electrolyte made possible a baseline resolved separation of 14 carboxylic acids. Good linearity and repeatability were obtained for both electrokinetic and hydrostatic injection modes. The usefulness of the method is demonstrated by the analysis of a snow sample.

  • 58. Dahlén, Johan
    et al.
    Karlsson, Stefan
    Bäckström, Mattias
    Örebro University, Department of Natural Sciences.
    Hagberg, Jessika
    Örebro University, Department of Natural Sciences.
    Pettersson, Håkan
    Determination of nitrate and other water quality parameters in groundwater from UV/Vis spectra employing partial least squares regression2000In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 40, no 1, p. 71-77Article in journal (Refereed)
    Abstract [en]

    The use of UV/Vis spectroscopy in combination with partial least squares (PLS) regression for the simultaneous prediction of nitrate and non-purgeable organic carbon (NPOC) in groundwaters was evaluated. A model of high quality was obtained using first order derivative spectra in the range 200–300 nm. Inclusion of non-UV-absorbing constituents in the modeling procedure, i.e., chloride, sulfate, fluoride, total carbon (TC), inorganic carbon (IC), alkalinity, pH and conductivity was also evaluated. This model seemed to be useful for prediction of chloride, TC, IC, alkalinity and conductivity, while its ability to predict sulfate, fluoride and pH was poor. In conclusion, application of PLS regression, which requires neither filtration of samples nor addition of chemicals, is a promising alternative for fast interpretation of geochemical patterns of groundwater quality.

  • 59.
    Dario, Mårten
    Örebro University, Department of Natural Sciences.
    Metal distribution and mobility under alkaline conditions2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The adsorption of an element, expressed as its distribution between liquid (aquatic) and solid phases in the biogeosphere, largely determines its mobility and transport properties. This is of fundamental importance in the assessment of the performance of e.g. geologic repositories for hazardous elements like radionuclides. Geologic repositories for low and intermediate level nuclear waste will most likely be based on concrete constructions in a suitable bedrock, leading to a local chemical environment with pH well above 12. At this pH metal adsorption is very high, and thus the mobility is hindered. Organic complexing agents, such as natural humic matter from the ground and in the groundwater, as well as components in the waste (cleaning agents, degradation products from ion exchange resins and cellulose, cement additives etc.) would affect the sorption properties of the various elements in the waste. Trace element migration from a cementitious repository through the pH- and salinity gradient created around the repository would be affected by the presence and creation of particulate matter (colloids) that may serve as carriers that enhance the mobility.

    The objective of this thesis was to describe and quantify the sorption of some selected elements representative of spent nuclear fuel (Eu, Am) and other heavy metals (Zn, Cd, Hg) in a clay/cement environment (pH 10-13) and in the pH-gradient outside this environment. The potential of organic complexing agents and colloids to enhance metal migration was also investigated. It was shown that many organic ligands are able to reduce trace metal sorption under these conditions. It was not possible to calculate the effect of well-defined organic ligands on the metal sorption in a cement environment by using stability constants from the literature. A simple method for comparing the effect of different complexing agents on metal sorption is, however, suggested.

    The stability in terms of the particle size of suspended colloidal matter (clays and an iron hydroxide) was measured by photon correlation spectroscopy. In the absence of large amounts of organic material, the present colloids will, in most cases, not enhance metal migration in a cementitious environment due to agglomeration of the colloidal phase at high pH and salinities.

    List of papers
    1. Sorption of europium onto titanium dioxide at high pH: influence of isosaccharinic and fulvic acid
    Open this publication in new window or tab >>Sorption of europium onto titanium dioxide at high pH: influence of isosaccharinic and fulvic acid
    (English)Manuscript (preprint) (Other academic)
    National Category
    Natural Sciences Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3125 (URN)
    Available from: 2004-04-28 Created: 2004-04-28 Last updated: 2017-10-18Bibliographically approved
    2. Effects of cement additives on radionuclide mobility
    Open this publication in new window or tab >>Effects of cement additives on radionuclide mobility
    2004 (English)In: Scientific basis for radioactive waste management XXVII: symposium held June 15-19, 2003, Kalmar, Sweden / [ed] Virginia M. Oversby, Lars O. Werme, Warrendale, Pa: Materials Research Society , 2004, p. 639-644Conference paper, Published paper (Other academic)
    Place, publisher, year, edition, pages
    Warrendale, Pa: Materials Research Society, 2004
    Series
    Materials Research Society symposium proceedings ; 807
    National Category
    Environmental Sciences Natural Sciences Chemical Sciences
    Research subject
    Environmental Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3126 (URN)1558997520 (ISBN)
    Available from: 2004-04-28 Created: 2004-04-28 Last updated: 2017-10-18Bibliographically approved
    3. Effects of technical adsorbents and cleaning agents in a cement matrix: a case study
    Open this publication in new window or tab >>Effects of technical adsorbents and cleaning agents in a cement matrix: a case study
    2004 (English)In: Scientific basis for nuclear waste management XXVII: symposium held June 15-19, 2003, Kalmar, Sweden / [ed] Virginia M. Oversby, Lars O. Werme, Warrendale, Pa: Materials Research Society , 2004, p. 371-376Conference paper, Published paper (Other academic)
    Place, publisher, year, edition, pages
    Warrendale, Pa: Materials Research Society, 2004
    Series
    Materials Research Society symposium proceedings ; 807
    National Category
    Natural Sciences Chemical Sciences Environmental Sciences
    Research subject
    Environmental Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3127 (URN)1558997520 (ISBN)
    Available from: 2004-04-28 Created: 2004-04-28 Last updated: 2017-10-18Bibliographically approved
    4. Sorption of europium on TiO2 and cement at high pH in the presence of organic ligands
    Open this publication in new window or tab >>Sorption of europium on TiO2 and cement at high pH in the presence of organic ligands
    2006 (English)In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 270, no 3, p. 495-505Article in journal (Refereed) Published
    Abstract [en]

    Organic substances present in radioactive waste lower the sorption of metal ions at the high pH in cement matrices and, hence, enhance their possible migration. The aim of this study was to develop a method to compare organic substances or their degradation products with respect to what extent they affect metal sorption. Batch sorption studies were performed with cement or TiO2 as solid phase and Eu(III) as a model element for trivalent lanthanides and actinides at pH 12.5 (representative of a cement waste matrix during the first approximately 100,000 years). Different kinds of ligands were studied in a broad concentration range, e.g., organic acids, cement additives, cleaning agents and degradation products from ion-exchange resin.

    National Category
    Natural Sciences Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3128 (URN)10.1007/s10967-006-0455-4 (DOI)
    Available from: 2004-04-28 Created: 2004-04-28 Last updated: 2017-12-14Bibliographically approved
    5. Impact of some hydrochemical parameters on the size distribution of illite, kaolin and montmorillonite
    Open this publication in new window or tab >>Impact of some hydrochemical parameters on the size distribution of illite, kaolin and montmorillonite
    (English)Manuscript (preprint) (Other academic)
    National Category
    Natural Sciences Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3129 (URN)
    Available from: 2004-04-28 Created: 2004-04-28 Last updated: 2017-10-18Bibliographically approved
    6. Sorption of europium to colloidal montmorillonite: impact of pH, an aquatic fulvic acid and calcium isosaccharinate
    Open this publication in new window or tab >>Sorption of europium to colloidal montmorillonite: impact of pH, an aquatic fulvic acid and calcium isosaccharinate
    (English)Manuscript (preprint) (Other academic)
    National Category
    Natural Sciences Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3130 (URN)
    Available from: 2004-04-28 Created: 2004-04-28 Last updated: 2017-10-18Bibliographically approved
    7. Sorption of Cd to colloidal ferric hydroxides: impact of pH and organic acids
    Open this publication in new window or tab >>Sorption of Cd to colloidal ferric hydroxides: impact of pH and organic acids
    1997 (English)In: Chemical speciation and bioavailability, ISSN 0954-2299, E-ISSN 2047-6523, Vol. 9, no 1, p. 3-14Article in journal (Refereed) Published
    Abstract [en]

    The sorption (both ad- and desorption) of Cd to or from colloidal ferric hydroxides as a function of pH, the concentration of organic acids (acetic acid (AA), EDTA, fulvic acid (FA) and malonic acid (MA)), the precipitation procedure for the ferric hydroxide as well as the contact time were investigated in the present study. The concentrations of Cd, colloids and organic acids were chosen to be representative of natural surface waters. The ferric hydroxide were either precipitated in presence of FA or the acid was mixed with the colloids after the purification steps. The presence of FA during the precipitation of ferric hydroxide, had an impact on the size distribution of the solid phase, but it did not have any influence on the sorption behaviour of Cd. The adsorption process was found to be relatively fast and largely pH-dependent. It was fully reversible when the pH was decreased, however, with somewhat slower kinetics. The addition of up to 1 mmol L-1 AA or MA did not cause any measurable desorption of Cd, probably due to the relatively weak complexes formed between Cd(II)-ions and the anions of the acids. Thermodynamic calculations of the distribution between different soluble Cd-species indicated that EDTA and FA would form stronger complexes with Cd. This was indicated in the experiments as enhanced adsorption at low pH-values due to the adsorption of Cd(II)-organic species, and an increase in the soluble fraction at high pH-values caused by competition for Cd(II)-ions between complex forming groups on the surfaces and the soluble organic ligands.

    National Category
    Natural Sciences Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3131 (URN)
    Available from: 2004-04-28 Created: 2004-04-28 Last updated: 2017-12-14Bibliographically approved
    8. Effects of a fulvic acid on the adsorption of mercury and cadmium on goethite
    Open this publication in new window or tab >>Effects of a fulvic acid on the adsorption of mercury and cadmium on goethite
    2003 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 304, no 1-3, p. 257-268Article in journal (Refereed) Published
    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.

    National Category
    Natural Sciences Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3132 (URN)10.1016/S0048-9697(02)00573-9 (DOI)
    Available from: 2004-04-28 Created: 2004-04-28 Last updated: 2017-12-14Bibliographically approved
  • 60.
    Dario, Mårten
    et al.
    Örebro University, Department of Natural Sciences.
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Sorption of europium onto titanium dioxide at high pH: influence of isosaccharinic and fulvic acidManuscript (preprint) (Other academic)
  • 61.
    Dario, Mårten
    et al.
    Örebro University, Department of Natural Sciences.
    Ledin, Anna
    Sorption of Cd to colloidal ferric hydroxides: impact of pH and organic acids1997In: Chemical speciation and bioavailability, ISSN 0954-2299, E-ISSN 2047-6523, Vol. 9, no 1, p. 3-14Article in journal (Refereed)
    Abstract [en]

    The sorption (both ad- and desorption) of Cd to or from colloidal ferric hydroxides as a function of pH, the concentration of organic acids (acetic acid (AA), EDTA, fulvic acid (FA) and malonic acid (MA)), the precipitation procedure for the ferric hydroxide as well as the contact time were investigated in the present study. The concentrations of Cd, colloids and organic acids were chosen to be representative of natural surface waters. The ferric hydroxide were either precipitated in presence of FA or the acid was mixed with the colloids after the purification steps. The presence of FA during the precipitation of ferric hydroxide, had an impact on the size distribution of the solid phase, but it did not have any influence on the sorption behaviour of Cd. The adsorption process was found to be relatively fast and largely pH-dependent. It was fully reversible when the pH was decreased, however, with somewhat slower kinetics. The addition of up to 1 mmol L-1 AA or MA did not cause any measurable desorption of Cd, probably due to the relatively weak complexes formed between Cd(II)-ions and the anions of the acids. Thermodynamic calculations of the distribution between different soluble Cd-species indicated that EDTA and FA would form stronger complexes with Cd. This was indicated in the experiments as enhanced adsorption at low pH-values due to the adsorption of Cd(II)-organic species, and an increase in the soluble fraction at high pH-values caused by competition for Cd(II)-ions between complex forming groups on the surfaces and the soluble organic ligands.

  • 62.
    Dario, Mårten
    et al.
    Örebro University, Department of Natural Sciences.
    Molera, Mireia
    Allard, Bert
    Effects of cement additives on radionuclide mobility2004In: Scientific basis for radioactive waste management XXVII: symposium held June 15-19, 2003, Kalmar, Sweden / [ed] Virginia M. Oversby, Lars O. Werme, Warrendale, Pa: Materials Research Society , 2004, p. 639-644Conference paper (Other academic)
  • 63.
    Dario, Mårten
    et al.
    Örebro University, Department of Natural Sciences.
    Molera, Mireia
    Allard, Bert
    Effects of technical adsorbents and cleaning agents in a cement matrix: a case study2004In: Scientific basis for nuclear waste management XXVII: symposium held June 15-19, 2003, Kalmar, Sweden / [ed] Virginia M. Oversby, Lars O. Werme, Warrendale, Pa: Materials Research Society , 2004, p. 371-376Conference paper (Other academic)
  • 64.
    Dario, Mårten
    et al.
    Örebro University, Department of Natural Sciences.
    Molera, Mireia
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Sorption of europium on TiO2 and cement at high pH in the presence of organic ligands2006In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 270, no 3, p. 495-505Article in journal (Refereed)
    Abstract [en]

    Organic substances present in radioactive waste lower the sorption of metal ions at the high pH in cement matrices and, hence, enhance their possible migration. The aim of this study was to develop a method to compare organic substances or their degradation products with respect to what extent they affect metal sorption. Batch sorption studies were performed with cement or TiO2 as solid phase and Eu(III) as a model element for trivalent lanthanides and actinides at pH 12.5 (representative of a cement waste matrix during the first approximately 100,000 years). Different kinds of ligands were studied in a broad concentration range, e.g., organic acids, cement additives, cleaning agents and degradation products from ion-exchange resin.

  • 65.
    Dario, Mårten
    et al.
    Örebro University, Department of Natural Sciences.
    Strömberg, Jessica
    Ledin, Anna
    Sorption of europium to colloidal montmorillonite: impact of pH, an aquatic fulvic acid and calcium isosaccharinateManuscript (preprint) (Other academic)
  • 66. dos Santos, Daniel
    et al.
    Scherbak, Nikolai
    Örebro University, Department of Natural Sciences.
    Strid, Åke
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Modelling Pisum sativum short-chain dehydrogenase/reductase enzymesManuscript (Other academic)
  • 67. Düker, Anders
    et al.
    Dario, Mårten
    Örebro University, Department of Natural Sciences.
    Ledin, Anna
    Impact of some hydrochemical parameters on the size distribution of illite, kaolin and montmorilloniteManuscript (preprint) (Other academic)
  • 68. Ebena, Gustav
    et al.
    Hagberg, Jessika
    Örebro University, Department of Natural Sciences.
    Carlsson, Erik
    Origin and distribution of low molecular weight organic acids and bacteria in a depth profile of a soil covered tailings impoundment in northern Sweden2007In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 92, no 2-3, p. 186-195Article in journal (Refereed)
    Abstract [en]

    The tailings at Kristineberg, northern Sweden, have a very low content of organic carbon, a feature common with many sulfidic tailing impoundments. Three different experiments were set-up to assess the role of carbon dioxide in a depth profile. Firstly, pore gas was collected in vials from ground water pipes at various points in the profile of a dry covered tailings impoundment and analyzed in the laboratory for CO2, O-2, N-2, H-2, and CH4 contents. Secondly, pore water was extracted from tension lysimeters at various depths. This water was analyzed for numbers of bacteria (iron-oxidizing and sulfur-oxidizing, both by MPN), and low molecular weight organic acids. Thirdly, Acidithiobacillus ferrooxidans (Strain DSMZ No 1927) was grown on a mixture of irradiated tailings and sterile water. The amount of organic acids produced was monitored. The largest bacterial count of iron-oxidizing bacteria, 4.7 x 10(5)/g tailings, was at the oxidation front, while the heterotrophic sulfur-oxidizing bacteria were mainly found in the unsaturated, oxidized zone, 2.65 x 10(4)/g tailings. The oxidation front was also the location where the largest amount of organic acids was found in the field study (formate 0.83 mg/l and acetate 0.51 mg/l). The acetic acid found coincides with the highest count of iron-oxidizing bacteria. The intrusion of O-2 and CO2 at the studied location is enough for microbiological activity, although the overall effect on AMD production is not addressed. The results from laboratory incubations indicate that the microbial community produces organic carbon with CO2 as the sole carbon source, up to 1.35 mg/l after 16 weeks measured as TOC. To conclude, we suggest that knowledge of the intrusion of both CO2 and O-2 is vital for a full understanding of the microbial ecology, and thus the weathering processes, in a dry covered tailings impoundment. Hence, the CO, produced in the till cover and entering the tailings ecosystem is crucial to the function of the ecosystem. (c) 2006 Elsevier B.V. All rights reserved.

  • 69.
    Edman, Katja
    et al.
    Örebro University, Department of Natural Sciences.
    Löfstedt, Håkan
    Berg, Peter
    Eriksson, Kåre
    Axelsson, Sara
    Bryngelsson, Ing-Liss
    Fedeli, Cecilia
    Exposure assessment to alpha- and beta-pinene, delta(3)-carene and wood dust in industrial production of wood pellets2003In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 47, no 3, p. 219-226Article in journal (Refereed)
    Abstract [en]

    The main aim of the study was to measure the exposure to monoterpenes (alpha- and beta-pinene and Delta(3)-carene) and wood dust during industrial production of wood pellets and briquettes. Additional aims were to compare the results from wood dust sampled on a filter with real time measurements using a direct reading instrument and to identify peak exposures to dust. Twenty-four men working at six companies involved in industrial production of wood pellets and briquettes participated in the study. Monoterpenes were measured by diffusive sampling and wood dust was measured as total dust. A data logger (DataRAM) was used for continuous monitoring of dust concentration for 18 of the participants. The sampling time was approximately 8 h. The personal exposure to monoterpenes ranged from 0.64 to 28 mg/m(3) and a statistically significant (Kruskal-Wallis test, P = 0.0002) difference in levels of monoterpenes for workers at different companies was seen. In the companies the personal exposure to wood dust varied between 0.16 and 19 mg/m(3) and for 10 participants the levels exceeded the present Swedish occupational exposure limit (OEL) of 2 mg/m(3). The levels of wood dust during the morning shift were significantly (Mann-Whitney test, P = 0.04) higher compared with the afternoon shift. Continuous registration of dust concentration showed peak values for several working operations, especially cleaning of truck engines with compressed air. For 24 workers in six companies involved in industrial production of wood pellets the personal exposure to monoterpenes was low and to wood dust high compared with the present Swedish OEL and previous studies in Swedish wood industries. Since the DataRAM can identify critical working tasks with high wood dust exposure a reduction in exposure levels could probably be achieved by changes in working routines and by the use of protective equipment

  • 70.
    Ekblad, Alf
    et al.
    Örebro University, Department of Natural Sciences.
    Boström, Björn
    Örebro University, Department of Natural Sciences.
    Holm, Anders
    Örebro University, Department of Natural Sciences.
    Comstedt, Daniel
    Örebro University, Department of Natural Sciences.
    Forest soil respiration rate and d13C is regulated by recent above ground weather conditions2005In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 143, no 1, p. 136-142Article in journal (Refereed)
    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.

  • 71.
    El Marghani, Ahmed
    Örebro University, Department of Natural Sciences.
    Cell signaling in inflammatory diseases and development of antiinflammatory drugs2008Licentiate thesis, monograph (Other academic)
  • 72.
    Enroth, Cristofer
    et al.
    Örebro University, Department of Natural Sciences.
    Strid, Åke
    Örebro University, Department of Natural Sciences.
    Crystal structure of a protein, structurally related to glycosyltransferases, encoded in the Rhodobacter blasticus atp operon2008In: Biochimica et Biophysica Acta - Proteins and Proteomics, ISSN 1570-9639, E-ISSN 1878-1454, Vol. 1784, no 2, p. 379-384Article in journal (Refereed)
    Abstract [en]

    The F1-ATP synthase atp operon in the proteobacterium Rhodobacter blasticus contains six open reading frames, encoding six hypothetical proteins. Five of these subunits, in the stoichiometry (ab)3gde make up the catalytic F1-ATP synthase complex similarly in bacteria, chloroplasts and mitochondria. The sixth gene of the Rb. blasticus atp operon, urf6, shows very little sequence homology to any protein of known structure or function. The gene has previously been cloned, the product (called majastridin) has been heterologously expressed in Escherichia coli, and purified to high homogeneity (Brosché et al. (1998) Eur. J. Biochem. 255: 87-92). We have solved the X-ray crystal structure and refined a model of majastridin to atomic resolution. Here we present the crystal structures of apo-majastridin and the complex of majastridin with Mn2+ and UDP and show it has extensive structural similarity to glycosyltransferases (EC 2.4). This is the first structure determined from a new group of distantly related bacterial proteins of at least six members. They share the identical amino acids that bind Mn2+and a triplet of amino acids in the putative sugar-binding site.

  • 73.
    Erdtman, Edvin
    Örebro University, Department of Natural Sciences.
    A theoretical study of 5-Aminolevulinic acid and its esters: properties and lipid permeability2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    5-aminolevulinic acid (5ALA) is a widely used prodrug in Photodynamic therapy (PDT). The target molecule in 5ALA-PDT is Protoporphyrin IX (PpIX), which is synthesized endogenously via the heme pathway in the cell. In this thesis; the structural and energetic properties of 5ALA, its methyl-, ethyl- and hexyl esters, four different 5ALA enols, and hydrated 5ALA have been investigated using Quantum Mechanical (QM) first principles calculations. The vacuum proton affinity (PA) of 5ALA is found to be in good agreement with other similar compounds. The keto-enol tautomerization mechanism of 5ALA has been studied, and a self-catalysis mechanism has been proposed to be the most probable. Molecular Dynamics (MD) simulations of a lipid bilayer have been performed to study the membrane permeability of 5ALA and its esters. In the simulations the molecules were inserted in the middle of the membrane, equilibrated, and then simulated in 20 ns. It has been found that there are some differences in penetration between the molecules studied. The methyl ester of 5ALA is diverging from the others by having its barrier not in the middle of the membrane, as the others have.

    List of papers
    1. Theoretical study of 5-aminolevulinic acid (5ALA) and some pharmaceutically important derivatives
    Open this publication in new window or tab >>Theoretical study of 5-aminolevulinic acid (5ALA) and some pharmaceutically important derivatives
    2007 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 434, no 1-3, p. 101-106Article in journal (Refereed) Published
    Abstract [en]

    5-Aminolevulinic acid (5ALA) is the key synthetic building block in protoporphyrin IX (PpIX), the heme chromophore in mitochondria. The addition of extracorporeal 5ALA and its alkyl ester derivatives are in current clinical use in photodynamical diagnostics and photodynamic therapy of tumors and skin disorders. In the current study density functional theory calculations are performed on 5ALA and its methyl, ethyl, and hexyl esters, in order to explore the basic chemical properties of these species. It is concluded that even in aqueous media the zwitterionic form of 5ALA is less stable than the non-zwitterionic one, that the local environment (lipid vs water) affects the energetics of reaction considerably, and that the hexyl species is most prone to hydrolysis of the three alkyl ester derivatives.

    Place, publisher, year, edition, pages
    Amsterdam: North-Holland Publishing Co, 2007
    Keywords
    5-aminolevulinic acid, 5ALA, B3LYP, DFT, Protonation states, Alkyl esters
    National Category
    Theoretical Chemistry Physical Chemistry
    Research subject
    Biochemistry; Physical Chemistry
    Identifiers
    urn:nbn:se:oru:diva-4092 (URN)10.1016/j.cplett.2006.11.084 (DOI)000243820100020 ()2-s2.0-33846018089 (Scopus ID)
    Available from: 2007-06-25 Created: 2007-06-25 Last updated: 2019-12-13Bibliographically approved
    2. Theoretical study of 5-aminolevulinic acid tautomerization: a novel self-catalyzed mechanism
    Open this publication in new window or tab >>Theoretical study of 5-aminolevulinic acid tautomerization: a novel self-catalyzed mechanism
    2008 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 112, no 18, p. 4367-4374Article in journal (Refereed) Published
    Abstract [en]

    5-Aminolevulinic acid (5ALA) is the key synthetic building block in protoporphyrin IX (PpIX), the heme chromophore in mitochondria. In this study density functional theory calculations were performed on the tautomers of 5ALA and the tautomerization reaction mechanism from its enolic forms (5-amino-4-hydroxypent-3-enoic acid and 5-amino-4-hydroxypent-4-enoic acid) to the more stable 5ALA. The hydrated form 5-amino-4,4-dihydroxypentanoic acid was also studied. The lowest energy pathway of 5ALA tautomerization is by means of autocatalysis, in that an oxygen of the carboxylic group transfers the hydrogen atom as a "crane", with an activation energy of similar to 15 kcal/mol. This should be compared to the barriers of about 35 kcal/mol for water assisted tautomerization, and 60 kcal/mol for direct hydrogen transfer. For hydration of 5ALA, the water catalyzed activation barrier is found to be similar to 35 kcal/mol, approximately 5 kcal/mol lower than direct hydration.

    Place, publisher, year, edition, pages
    Washington DC: American Chemical Society, 2008
    Keywords
    Aminolevulinic Acid/*chemistry, Carboxylic Acids/chemistry, Catalysis, Isomerism, Protons, Quantum Theory, Thermodynamics, Water/chemistry
    National Category
    Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy) Physical Chemistry Theoretical Chemistry
    Research subject
    Biochemistry; Physical Chemistry
    Identifiers
    urn:nbn:se:oru:diva-4625 (URN)10.1021/jp7118197 (DOI)000255486400026 ()18416542 (PubMedID)2-s2.0-43949116597 (Scopus ID)
    Available from: 2008-10-13 Created: 2008-10-13 Last updated: 2019-12-13Bibliographically approved
    3. Modelling the behavior of 5-aminolevulinic acid and its alkyl esters in a lipid bilayer
    Open this publication in new window or tab >>Modelling the behavior of 5-aminolevulinic acid and its alkyl esters in a lipid bilayer
    2008 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 463, no 1-3, p. 178-182Article in journal (Refereed) Published
    Abstract [en]

    5-Aminolevulinic acid (5ALA) and ester derivates thereof are used as prodrugs in photodynamic therapy (PDT). The behavior of 5ALA and three esters of 5ALA in a DPPC lipid bilayer is investigated. In particular, the methyl ester displays a very different free energy profile, where the highest barrier is located in the region with highest lipid density, while the others have their peak in the middle of the membrane, and also displays a considerably lower permeability coefficient than neutral 5ALA and the ethyl ester. The zwitterion of 5ALA has the highest permeability constant, but a significant free energy minimum in the polar head-group region renders an accumulation in this region.

    Place, publisher, year, edition, pages
    Amsterdam: North-Holland Publishing Co, 2008
    Keywords
    Molecular-dynamics simulations, photodynamic therapy, adenocarcinoma cells, beta transporters, hydrated DPPC, derivates, permeation, protoporphyrin, transition, membranes
    National Category
    Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy) Medicinal Chemistry Physical Chemistry Theoretical Chemistry
    Research subject
    Biochemistry; Physical Chemistry
    Identifiers
    urn:nbn:se:oru:diva-4624 (URN)10.1016/j.cplett.2008.08.021 (DOI)000259150400035 ()2-s2.0-51349091343 (Scopus ID)
    Available from: 2008-10-13 Created: 2008-10-13 Last updated: 2019-12-13Bibliographically approved
  • 74.
    Erdtman, Edvin
    et al.
    Örebro University, Department of Natural Sciences.
    dos Santos, Daniel J. V. A.
    Löfgren, Lennart
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Modelling the behavior of 5-aminolevulinic acid and its alkyl esters in a lipid bilayer2008In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 463, no 1-3, p. 178-182Article in journal (Refereed)
    Abstract [en]

    5-Aminolevulinic acid (5ALA) and ester derivates thereof are used as prodrugs in photodynamic therapy (PDT). The behavior of 5ALA and three esters of 5ALA in a DPPC lipid bilayer is investigated. In particular, the methyl ester displays a very different free energy profile, where the highest barrier is located in the region with highest lipid density, while the others have their peak in the middle of the membrane, and also displays a considerably lower permeability coefficient than neutral 5ALA and the ethyl ester. The zwitterion of 5ALA has the highest permeability constant, but a significant free energy minimum in the polar head-group region renders an accumulation in this region.

  • 75.
    Erdtman, Edvin
    et al.
    Örebro University, School of Science and Technology.
    dos Santos, Daniel J. V. A.
    Örebro University, School of Science and Technology.
    Löfgren, Lennart
    Orebro Univ Hosp, Head & Neck Oncol Ctr, S-70185 Orebro, Sweden.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Modelling the behavior of 5-aminolevulinic acid and its alkyl esters in a lipid bilayer (vol 463, pg 178, 2008)2009In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 470, no 4-6, p. 369-369Article in journal (Refereed)
  • 76.
    Erdtman, Edvin
    et al.
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Theoretical study of 5-aminolevulinic acid (5ALA) and some pharmaceutically important derivatives2007In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 434, no 1-3, p. 101-106Article in journal (Refereed)
    Abstract [en]

    5-Aminolevulinic acid (5ALA) is the key synthetic building block in protoporphyrin IX (PpIX), the heme chromophore in mitochondria. The addition of extracorporeal 5ALA and its alkyl ester derivatives are in current clinical use in photodynamical diagnostics and photodynamic therapy of tumors and skin disorders. In the current study density functional theory calculations are performed on 5ALA and its methyl, ethyl, and hexyl esters, in order to explore the basic chemical properties of these species. It is concluded that even in aqueous media the zwitterionic form of 5ALA is less stable than the non-zwitterionic one, that the local environment (lipid vs water) affects the energetics of reaction considerably, and that the hexyl species is most prone to hydrolysis of the three alkyl ester derivatives.

  • 77.
    Erdtman, Edvin
    et al.
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Theoretical study of 5-aminolevulinic acid tautomerization: a novel self-catalyzed mechanism2008In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 112, no 18, p. 4367-4374Article in journal (Refereed)
    Abstract [en]

    5-Aminolevulinic acid (5ALA) is the key synthetic building block in protoporphyrin IX (PpIX), the heme chromophore in mitochondria. In this study density functional theory calculations were performed on the tautomers of 5ALA and the tautomerization reaction mechanism from its enolic forms (5-amino-4-hydroxypent-3-enoic acid and 5-amino-4-hydroxypent-4-enoic acid) to the more stable 5ALA. The hydrated form 5-amino-4,4-dihydroxypentanoic acid was also studied. The lowest energy pathway of 5ALA tautomerization is by means of autocatalysis, in that an oxygen of the carboxylic group transfers the hydrogen atom as a "crane", with an activation energy of similar to 15 kcal/mol. This should be compared to the barriers of about 35 kcal/mol for water assisted tautomerization, and 60 kcal/mol for direct hydrogen transfer. For hydration of 5ALA, the water catalyzed activation barrier is found to be similar to 35 kcal/mol, approximately 5 kcal/mol lower than direct hydration.

  • 78.
    Ericson Jogsten, Ingrid
    et al.
    Örebro University, Department of Natural Sciences.
    Gómez, Mercedes
    Nadal, Martí
    van Bavel, Bert
    Örebro University, Department of Natural Sciences.
    Lindström, Gunilla
    Örebro University, Department of Natural Sciences.
    Domingo, José L.
    Perfluorinated chemicals in blood of residents in Catalonia (Spain) in relation to age and gender: a pilot study2007In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 33, no 5, p. 616-623Article in journal (Refereed)
    Abstract [en]

    Fluorinated organic compounds (FOCs) are a group of chemicals widely used as surfactants, lubricants, polymers, and fire-fighting foams. Recent studies have shown the ubiquitous distribution of FOCs in the environment, wildlife, and humans. We here report the results of a pilot study conducted to provide preliminary data on the levels of 13 FOCs in the blood of 48 residents in Catalonia, Spain, in relation to gender and age (25+/-5 and 55+/-5 years). The highest mean concentration was obtained for perfluorooctane sulfonate (PFOS, 7.64 ng/ml), followed by perfluorohexane sulfonate (PFHxS, 3.56 ng/ml) and perfluorooctanoic acid (PFOA, 1.80 ng/ml). Four other FOCs showed mean levels between 0.30 and 0.44 ng/ml, whereas those of the remaining 6 compounds were below the detection limit. Regarding gender, the blood levels of PFHxS and PFOA were significantly higher (p<0.05) in men than in women, while differences according to age were only noted for PFHxS (p<0.05) and perfluorooctane sulfonamide (PFOSA) (p<0.001), for which the levels were higher in the younger (25+/-5 years) group of subjects. A significant correlation between PFOS levels and those of the remaining detected FOCs (except PFDA) was found. In general terms, the current FOC concentrations were lower than those found in recent studies concerning levels of these chemicals in human blood and serum of subjects from different countries.

  • 79.
    Ericson Jogsten, Ingrid
    et al.
    Örebro University, Department of Natural Sciences.
    Hagberg, Jessika
    Örebro University, Department of Natural Sciences.
    van Bavel, Bert
    Örebro University, Department of Natural Sciences.
    Lindström, Gunilla
    Örebro University, Department of Natural Sciences.
    Detection of polybrominated dibenzo-p dioxins and furans (PBDD/Fs) in human tissue from Sweden2008In: Organohalogen Compounds, ISSN 1026-4892, Vol. 70, p. 220-223Article in journal (Refereed)
  • 80.
    Eriksson, Emma S. E.
    et al.
    Örebro University, Department of Natural Sciences.
    Guedes, Rita C.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Redox and debromination reactions of brominated hypericin2008In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 108, no 11, p. 1921-1929Article in journal (Refereed)
    Abstract [en]

    Phototoxic and radical-generating debromination reactions of monobrominated hypericin with bromine at one of four possible positions were investigated using density functional theory. The study was performed on two closely lying conformational isomers, differing in the relative orientations of the two anthracene units of the hypericin core. Calculated adiabatic electron affinities show that the molecules have the ability to, in aqueous solution, extract an electron from the surrounding. The electron might then be passed on to molecular oxygen, forming reactive superoxide radical anions. If electron extraction from the molecule does not occur in this step, the molecule might dissociate, generating a negatively charged bromine as a leaving group and a hypericin radical capable of forming direct binding to biological molecules. This reaction was found possible for those species substituted by Br at two of the four positions, with barriers of 13 kcal/mol in aqueous solution. Debromination was not found energetically possible for neither the neutral ground state compounds nor the bay-deprotonated species.

  • 81. Eriksson, Kåre
    et al.
    Hagstrom, Katja
    Örebro University, Department of Natural Sciences.
    Axelsson, Sara
    Nylander-French, Leena
    Tape-stripping as a method for measuring dermal exposure to resin acids during wood pellet production2008In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 10, no 3, p. 345-352Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to develop a sensitive and specific method for quantifying dermal exposure to the resin acids 7-oxodehydroabietic acid (7-OXO), dehydroabietic acid (DHAA), abietic acid ( AA), and pimaric acid (PA). In addition the method was evaluated in occupational settings during production of wood pellets. Tape-strips were spiked with the substances to evaluate the recovery of the acids from the tape. The removal efficiency of the tape was assessed by tape-stripping a specified area on a glass plate spiked with resin acids. The recovery of the acids from human skin in vivo was evaluated by applying acids in methanol onto the skin of volunteers. Occupational dermal exposure to the resin acids was assessed by tape-stripping the skin of workers involved in the production of wood pellets. The resin acids were analyzed by liquid chromatography mass spectrometry (LC-MS). The limit of detection was 15 pg (7-OXO), 150 pg ( DHAA), 285 pg ( AA) and 471 pg ( PA) per injection. The recovery from spiked tapes was in general 100%. The removal efficiency of the tape was 48-101%. Recovery tests from human skin in vivo showed a mean recovery of 27%. Quantifiable amounts of resin acids were observed on four different skin areas with an increase in exposure during a work shift. This study shows that occupational dermal exposure to resin acids can be assessed by tape-stripping and quantified by LC-MS.

  • 82. Eriksson, Kåre
    et al.
    Hagström, Katja
    Örebro University, Department of Natural Sciences.
    Axelsson, Sara
    Nylander-French, Leena
    Tape-stripping as a method for measuring dermal exposure to resin acids during wood pellet productionManuscript (preprint) (Other academic)
  • 83.
    Eriksson, Leif A.
    et al.
    Örebro University, Department of Natural Sciences.
    Russo, Nino
    Ugalde, Jesus M.
    Second International Theoretical Biophysics Symposium, Örebro University, Sweden, June 28–July 1, 20052007In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 107, no 2, p. 66p. 259-260Article in journal (Refereed)
  • 84. Fleig, Timo
    et al.
    Edvardsson, David
    Örebro University, Department of Natural Sciences.
    Banks, Simon T.
    Eland, John H. D.
    A theoretical and experimental study of the double photoionisation of molecular bromine and a new double ionisation mechanism2008In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 343, no 2-3, p. 270-280Article in journal (Refereed)
    Abstract [en]

    Complete double photoionisation spectra of Br2 have been measured at 30.4, 37.9 and 40.7 nm. The spectra are compared with high level relativistic calculations of the state energies and potential energy surfaces of Br22 + carried out within a four-component relativistic framework. Excellent agreement is obtained between experimental and theoretical relative state energies which allows for an assignment of the main part of the spectrum. Spectroscopic constants and tunnelling lifetimes have been determined for quasi-bound states. From the experimentally determined electron distributions we deduce that a new form of dissociative autoionisation plays a major role in double photoionisation of bromine and other molecules where certain atomic ions are major fragmentation products. © 2007 Elsevier B.V. All rights reserved.

  • 85. Fuglei, E.
    et al.
    Bustnes, J. O.
    Hop, H.
    Mørk, T.
    Björnfoth, Helen
    Örebro University, Department of Natural Sciences.
    van Bavel, Bert
    Örebro University, Department of Natural Sciences.
    Environmental contaminants in arctic foxes (Alopex lagopus) in Svalbard: relationships with feeding ecology and body condition2007In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 146, no 1, p. 128-138Article in journal (Refereed)
    Abstract [en]

    Adipose tissues from 20 arctic foxes (Alopex lagopus) of both sexes from Svalbard were analysed for polybrominated diphenyl ether (PBDE), polychlorinated biphenyl (PCB), p,p'-dichlorodiphenyltrichloroethane (DDE), chlordane, and hexachlorobenzene (HCB) concentrations. Gender (0.43<p<0.97) and age (0.15<p<0.95) were not significantly related to any of the organohalogen groups. Body condition showed a significant inverse relationship with SigmaPBDE, SigmaChlordane and HCB, suggesting that increased tissue contaminant concentrations are associated with depletion of adipose tissue. The seasonal cyclic storage and mobilisation of adipose tissue, characteristic in Arctic wildlife, may then provide increased input of contaminants to sensitive, vital effect organs. Trophic position was estimated by delta(15)N from muscle samples and showed significantly positive relationship with all contaminants, with the exception of HCB concentrations. This indicates that foxes feeding at high trophic levels had higher tissue contaminant levels as a result of bioaccumulation in the food chain.

  • 86.
    Garipov, Emil
    et al.
    Technical University of Sofia, Bulgaria.
    Stoilkov, Teodor
    Technical University of Sofia, Bulgaria.
    Kalaykov, Ivan
    Örebro University, Department of Natural Sciences.
    Multiple regressive model adaptive control2008In: New developments in robotics automation and control / [ed] Aleksandar Lazinica, Rijeka, Croatia: InTech , 2008, p. 59-84Chapter in book (Refereed)
  • 87. Geibe, Christine E.
    et al.
    Danielsson, Rolf
    van Hees, Patrick A. W.
    Örebro University, Department of Natural Sciences.
    Lundstrom, Ulla S.
    Comparison of soil solution chemistry sampled by centrifugation, two types of suction lysimeters and zero-tension lysimeters2006In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 21, no 12, p. 2096-2111Article in journal (Refereed)
    Abstract [en]

    The choice of sampling method for soil solution is of great importance. In this paper soil solution chemistry sampled by centrifugation, two types of suction lysimeters and zero-tension lysimeters have been studied with the purpose of investigating systematic differences between them. The samples were taken at 4 depths from an acidified forest soil as well as from adjacent lime and ash treated soils. A centrifugation drainage method was compared with two types of suction lysimeters ('Rhizon' and 'Prenart') and zero-tension lysimeters. About half of the 27 variables measured showed a significant difference between the sampling methods used. Typically the centrifuged samples had lower pH (4.0 vs. 4.4), Ca (21 mu M vs. 30 mu M) and Mg (25 mu M vs. 34 mu M) concentrations and higher CI (330 mu M vs. 230 mu M) and DOC (4.4 mM vs. 3.2 mM) concentrations than the Rhizon lysimeters. Also the other lysimeters showed significant differences compared to the centrifuged samples for about half the number of analytes. Centrifuged samples had higher concentrations of all analytes except NO3 and PO4 compared to zero-tension lysimeters and also for all analytes except NO3 and Al compared to Prenart lysimeters. Among the environmental factors considered depth showed an influence to some extent, while sampling occasion had a great significant impact on the difference between the centrifugation method and the Rhizon lysimeters. Factors like individual pits or soil treatment did not show any influence on the difference between the methods. (c) 2006 Elsevier Ltd. All rights reserved.

  • 88. Geijer, Håkan
    et al.
    Norrman, Eva
    Örebro University, Department of Natural Sciences.
    Persliden, Jan
    Optimising the tube potential for lumbar spine radiography using a flat-panel digital detectorManuscript (preprint) (Other academic)
  • 89. Geijer, Håkan
    et al.
    Norrman, Eva
    Örebro University, Department of Natural Sciences.
    Persliden, Jan
    Optimizing the tube potential for lumbar spine radiography with a flat-pane digital detector2009In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 82, no 973, p. 62-68Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to find the optimal settings for lumbar spine radiography with a flat-panel detector. A CDRAD contrast-detail phantom was imaged at various tube potentials, system speeds and filtration settings. Factorial experiments yielded a range of optimized exposure settings, which were submitted to visual grading analysis with images of an Alderson phantom. The first optimized settings involved a system speed increase from 400 to 800. For anteroposterior projection, the optimal tube potential was reduced from the default of 77 kV to 60 kV to give the best image quality without increasing the effective dose, or to 66 kV to give the lowest dose without reducing image quality. For lateral projection, the tube potential was similarly reduced from the default of 90 kV to 70 kV or 77 W. Visual grading analysis confirmed the results, with significantly better image quality when optimizing for image quality. The study thus shows that the tube potential can be reduced as long as the system speed is increased simultaneously. This leads to a lower effective dose and/or increased image quality depending on the settings chosen. The factorial experiments provided a powerful way to evaluate several parameters concomitantly.

  • 90. Gittins, John R.
    et al.
    Schuler, Mary A.
    Strid, Åke
    Örebro University, Department of Natural Sciences.
    Identification of a novel nuclear factor-binding site in the Pisum sativum sad gene promoters2002In: Biochimica et Biophysica Acta, Gene Structure and Expression, ISSN 0167-4781, E-ISSN 1879-2634, Vol. 1574, no 3, p. 231-244Article in journal (Refereed)
    Abstract [en]

    DNA fragments containing the 5' promoter regions of the Pisum sativum sadA and sadC genes were amplified from genomic DNA, cloned and sequenced. These sequences contain a number of conserved cis-acting elements, which are potentially involved in stress-induced transcription of the sad genes. To determine whether any of the identified elements are active in binding nuclear factors in vitro, 11 60-bp overlapping (by 30 bp) DNA probe fragments covering the proximal sadC promoter sequence (360 bp) were used in electrophoretic mobility shift assays with competition. Binding activities were compared in nuclear extracts from control, UV-B-stressed and wounded pea leaves. The pattern of DNA binding was almost identical with all three extracts, with one 30-bp region being the predominant site for factor binding. Using overlapping sub-fragments of this region, the majority of the specific binding could be attributed to the novel 11-bp GC-rich sequence GTGGCGCCCAC. An almost identical sequence is conserved in the sadA promoter. This motif has features in common with a number of recognised cis-elements, which suggests a possible binding site for factors which play a role in regulating sad gene transcription.

  • 91.
    Grahn, Evastina
    Örebro University, Department of Natural Sciences.
    Lake sediment as environmental archive: natural and anthropogenic influence on the chronology of trace elements2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The focus of this thesis is the historical pollution of some seldom-monitored trace elements (SMTEs; Ag, Be, Ga, In, Sb and Tl) that have been involuntarily released for several thousands of years but whose usage have increased during the industrial era. Sediment cores from four rural lakes in a south to north transect in central Sweden, and two urban lakes have been used as environmental archives for chronological studies. The historical development of the SMTEs is put in perspective of frequently monitored elements (Cd, Cu, Pb and Zn) that serve as a well-known anthropogenic signal. Dating of the sediments is made with 210Pb, 137Cs and 239,240Pu as well as acid leachable lead and the 206Pb/207Pb ratio. The impact of diagenetic redistribution is included, when necessary.

    The results show that site-specific reference concentrations are required in order to estimate the present pollution as well as its historical development. Atmospheric deposition is the principal pathway of transport in rural lakes and the concentrations are lowered towards the north. It is not possible from this material, however, to separate the direct deposition on the lake surfaces from the contribution from their catchments. From 21Pb, acid-leachable Pb and the 206Pb/207Pb ratio a minimum of four periods of pollution can be discerned. For the SMTEs the quantitatively most important period of pollution took place from the Second World War until present. The growth of the domestic industrialisation as well as the early industrialisation of central Europe and the British Isles are also distinguishable. The pollution history of Ag, In and Sb goes back for several centuries as a result of metal processing whereas the levels of thallium mainly increase as a result of industrialisation. For Ag and Tl in-sediment diagenetic redistribution limits the precision of the historical estimate. The preliminary interpretation of 137Cs and 239,240Pu indicates that they are less suitable as chronological markers in the system studied. The urban impact on the trace metal sediment content in the urban lakes was lower than expected, except for Au. There is a large impact from hydrological conditions on the studied system why further investigations are recommended.

    List of papers
    1. Sediment reference concentrations of seldom monitored trace elements (Ag, Be, In, Ga, Sb, Tl) in four Swedish boreal lakes: comparison with commonly monitored elements
    Open this publication in new window or tab >>Sediment reference concentrations of seldom monitored trace elements (Ag, Be, In, Ga, Sb, Tl) in four Swedish boreal lakes: comparison with commonly monitored elements
    2006 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 367, no 2-3, p. 778-790Article in journal (Refereed) Published
    Abstract [en]

    This paper presents reference and recent acid-leachable concentrations of some seldom monitored trace elements (SMTE; Ag, Be, Ga, In, Sb and Tl) in sediments from four boreal oligotrophic lakes in a south to north transect in Sweden. For comparison commonly monitored trace elements (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) are included as well as those of relevance for redistribution processes (Al, Ca, Fe, Mg and Mn).

    Pore water pH and the corresponding solid/solution distribution coefficients (Kd) indicated that redistribution of the elements due to acidification is minor. The depth of impact was defined as the level in the sediment where the mean values became constant on successive exclusion of metal concentrations in overlying strata. Reference concentrations were calculated below the depth of impact. The present concentration changes are estimated by the ratio between the average concentration above the depth of impact and the reference concentration.

    Reference concentration ranges for the SMT-elements are (mg/kg, dry wt.): Ag 0.16–0.66; Be 1.6–3.7; Ga 2.0–5.1; In 0.05–0.22; Sb 0.05–0.11 and Tl 0.17–0.70. The concentration ratios for these elements ranged in the two most southern lakes from 1.5 to 4.5 and in the two northern ones from 0.6 to 1.6. A high correlation between Kd for the SMT-elements, and iron, except for Sb and Tl, infer that the biogeochemistry of iron is quantitatively important for the accumulation of these elements.

    The reference concentration ranges for the commonly monitored trace elements are (mg/kg, dry wt.): As 7.0–29.6; Cd 0.33–0.98; Co 5.7–23.8; Cr 15.2–26.1; Cu 27.6–58.4; Ni 5.4–20.8; Pb 44–96. The corresponding concentration ratios were 1.2–18 (second highest 3.9) in the two most southern lakes and 0.8–1.6 in the two northern ones. Declining ratios were found from south to north, most obvious for cobalt and zinc. The copper ratios did not show a regional pattern, partly because of the impact from old mine waste.

    Increased concentrations of Ag, Be, Ga, In, Sb and Tl in recent sediments up to 4.5 times the reference levels in combination with the geographical pattern infer an elevated loading of these elements.

    National Category
    Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3058 (URN)10.1016/j.scitotenv.2006.01.018 (DOI)
    Available from: 2006-03-09 Created: 2006-03-09 Last updated: 2017-12-14Bibliographically approved
    2. Historical pollution of seldom monitored trace elements in Sweden - Part A: sediment properties and chronological indicators
    Open this publication in new window or tab >>Historical pollution of seldom monitored trace elements in Sweden - Part A: sediment properties and chronological indicators
    2006 (English)In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 8, no 7, p. 721-731Article in journal (Refereed) Published
    Abstract [en]

    Sediment cores from four small oligotrophic boreal lakes, with minor acidification, in remote regions of central Sweden were used for historical interpretation of their metal content, with focus on Cu, Cd, Pb and Zn in Lake Stensjön, which has the longest sediment record (at least two centuries according to 210Pb dating). Comparison is made with the other three lakes. Major and trace elements in lake water, porewater and the acid-leached (HNO3) solid sediment phase was analysed with ICP-MS. In addition, general lake water chemistry, TOC and principal anions were measured in the aqueous phases. Redistribution processes were interpreted from geochemical modelling. The solid/solution distribution of pe/pH sensitive elements, indicates a minor diagenetic redistribution and the concentration profiles are therefore suitable for chronological evaluation. The ratios of Al, Ti, Sc and V, indicated a qualitative shift of sedimenting material a century ago, which did not have any impact on the retention of trace elements. Lead had a concentration profile, supported by the 206Pb/207Pb ratio, where it was possible to distinguish preindustrial conditions, early industrialisation in Europe, industrialisation in Sweden, and the use of leaded petrol after the Second World War. Cadmium showed a similar concentration pattern. The zinc profile resembled that of cadmium, but with less enrichment. Local lithogenic sources are believed to be quantitatively important. The solid/solution distribution (Kd) was independent of depth for all four elements. The sediment concentrations of copper and zinc are not related to early industrialisation but its concentration has doubled since the Second World War.

    National Category
    Chemical Sciences Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3059 (URN)10.1039/B601944G (DOI)16826285 (PubMedID)
    Available from: 2006-03-09 Created: 2006-03-09 Last updated: 2017-12-14Bibliographically approved
    3. Historical pollution of seldom monitored trace elements in Sweden: Part B: sediment analysis of silver, antimony, thallium and indium
    Open this publication in new window or tab >>Historical pollution of seldom monitored trace elements in Sweden: Part B: sediment analysis of silver, antimony, thallium and indium
    2006 (English)In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 8, no 7, p. 732-744Article in journal (Refereed) Published
    Abstract [en]

    Sediment cores from four boreal and remote lakes in a south to north transect in central Sweden were analysed for acid leachable silver, antimony, thallium and indium in the solid sediment phase and the corresponding porewater. Dating of the cores was made by their content of acid leachable lead and the 206Pb/207Pb ratio, in one lake also by 210Pb. The impact of diagenesis on element redistribution in the sediments was included and found to be minor except for thallium. The results show lowered concentrations towards the north and most intense accumulation after the Second World War, which is taken as evidence for atmospheric deposition being the primary source. Indium has declining concentrations in recent strata while silver and antimony increase. Thallium has lowered acid-leachable concentrations in recent strata. For all metals the impact of domestic industrialisation as well as the early industrialisation of central Europe is discernible. Only thallium appears to reach a geological background at depths that correspond to the late 18th century. For the other metals elevated levels are concluded.

    National Category
    Environmental Sciences Chemical Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3053 (URN)10.1039/B601948J (DOI)
    Available from: 2006-03-09 Created: 2006-03-09 Last updated: 2017-12-14Bibliographically approved
    4. Seldom monitored trace elements (Ag, Au, Ga, In, Sb, Tl) in two urban lake sediments in Central Sweden: a case study
    Open this publication in new window or tab >>Seldom monitored trace elements (Ag, Au, Ga, In, Sb, Tl) in two urban lake sediments in Central Sweden: a case study
    (English)Manuscript (Other academic)
    National Category
    Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3061 (URN)
    Available from: 2006-03-09 Created: 2006-03-09 Last updated: 2017-10-18Bibliographically approved
    5. Failure of 137Cs and 239/240Pu dating of lake sediments: fallout from nuclear weapons testing and from the Chernobyl accident as well as redistribution processes?
    Open this publication in new window or tab >>Failure of 137Cs and 239/240Pu dating of lake sediments: fallout from nuclear weapons testing and from the Chernobyl accident as well as redistribution processes?
    Show others...
    (English)Manuscript (Other academic)
    National Category
    Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3062 (URN)
    Available from: 2006-03-09 Created: 2006-03-09 Last updated: 2017-10-18Bibliographically approved
  • 92.
    Grahn, Evastina
    et al.
    Örebro University, Department of Natural Sciences.
    Greis, Christina
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Örebro University, Department of Natural Sciences.
    Düker, Anders
    Örebro University, Department of Natural Sciences.
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Pettersson, Håkan
    Failure of 137Cs and 239/240Pu dating of lake sediments: fallout from nuclear weapons testing and from the Chernobyl accident as well as redistribution processes?Manuscript (Other academic)
  • 93.
    Grahn, Evastina
    et al.
    Örebro University, Department of Natural Sciences.
    Greis, Christina
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Düker, Anders
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Pettersson, Håkan
    Failure of 137Cs and 239,240Pu dating of lake sediments: fallout from nuclear weapons testing, the Chernobyl accident and redistribution processes?Manuscript (preprint) (Other academic)
  • 94.
    Grahn, Evastina
    et al.
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Örebro University, Department of Natural Sciences.
    Düker, Anders
    Örebro University, Department of Natural Sciences.
    Sediment reference concentrations of seldom monitored trace elements (Ag, Be, In, Ga, Sb, Tl) in four Swedish boreal lakes: comparison with commonly monitored elements2006In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 367, no 2-3, p. 778-790Article in journal (Refereed)
    Abstract [en]

    This paper presents reference and recent acid-leachable concentrations of some seldom monitored trace elements (SMTE; Ag, Be, Ga, In, Sb and Tl) in sediments from four boreal oligotrophic lakes in a south to north transect in Sweden. For comparison commonly monitored trace elements (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) are included as well as those of relevance for redistribution processes (Al, Ca, Fe, Mg and Mn).

    Pore water pH and the corresponding solid/solution distribution coefficients (Kd) indicated that redistribution of the elements due to acidification is minor. The depth of impact was defined as the level in the sediment where the mean values became constant on successive exclusion of metal concentrations in overlying strata. Reference concentrations were calculated below the depth of impact. The present concentration changes are estimated by the ratio between the average concentration above the depth of impact and the reference concentration.

    Reference concentration ranges for the SMT-elements are (mg/kg, dry wt.): Ag 0.16–0.66; Be 1.6–3.7; Ga 2.0–5.1; In 0.05–0.22; Sb 0.05–0.11 and Tl 0.17–0.70. The concentration ratios for these elements ranged in the two most southern lakes from 1.5 to 4.5 and in the two northern ones from 0.6 to 1.6. A high correlation between Kd for the SMT-elements, and iron, except for Sb and Tl, infer that the biogeochemistry of iron is quantitatively important for the accumulation of these elements.

    The reference concentration ranges for the commonly monitored trace elements are (mg/kg, dry wt.): As 7.0–29.6; Cd 0.33–0.98; Co 5.7–23.8; Cr 15.2–26.1; Cu 27.6–58.4; Ni 5.4–20.8; Pb 44–96. The corresponding concentration ratios were 1.2–18 (second highest 3.9) in the two most southern lakes and 0.8–1.6 in the two northern ones. Declining ratios were found from south to north, most obvious for cobalt and zinc. The copper ratios did not show a regional pattern, partly because of the impact from old mine waste.

    Increased concentrations of Ag, Be, Ga, In, Sb and Tl in recent sediments up to 4.5 times the reference levels in combination with the geographical pattern infer an elevated loading of these elements.

  • 95.
    Grahn, Evastina
    et al.
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Örebro University, Department of Natural Sciences.
    Düker, Anders
    Örebro University, Department of Natural Sciences.
    Seldom monitored trace elements (Ag, Au, Ga, In, Sb, Tl) in two urban lake sediments in Central Sweden: a case studyManuscript (Other academic)
  • 96.
    Grahn, Evastina
    et al.
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Örebro University, Department of Natural Sciences.
    Karlsson, Ulrika
    Örebro University, Department of Natural Sciences.
    Düker, Anders
    Örebro University, Department of Natural Sciences.
    Historical pollution of seldom monitored trace elements in Sweden: Part B: sediment analysis of silver, antimony, thallium and indium2006In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 8, no 7, p. 732-744Article in journal (Refereed)
    Abstract [en]

    Sediment cores from four boreal and remote lakes in a south to north transect in central Sweden were analysed for acid leachable silver, antimony, thallium and indium in the solid sediment phase and the corresponding porewater. Dating of the cores was made by their content of acid leachable lead and the 206Pb/207Pb ratio, in one lake also by 210Pb. The impact of diagenesis on element redistribution in the sediments was included and found to be minor except for thallium. The results show lowered concentrations towards the north and most intense accumulation after the Second World War, which is taken as evidence for atmospheric deposition being the primary source. Indium has declining concentrations in recent strata while silver and antimony increase. Thallium has lowered acid-leachable concentrations in recent strata. For all metals the impact of domestic industrialisation as well as the early industrialisation of central Europe is discernible. Only thallium appears to reach a geological background at depths that correspond to the late 18th century. For the other metals elevated levels are concluded.

  • 97. Grand, André
    et al.
    Morell, C
    Labet, Vanessa
    Cadet, Jean
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    *H and *OH radical reactions with 5-methylcytosine2007In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 111, no 37, p. 8968-8972Article in journal (Refereed)
  • 98.
    Greis, Christina
    Örebro University, Department of Natural Sciences.
    Rapid analysis of actinide isotopes using quadrupole ICP-MS for emergency preparedness and environmental monitoring2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Transuranium elements in the environment are mainly derived from nuclear weapons testing and the nuclear fuel cycle. Of growing concern are illicit nuclear trafficking and the threat of terror acts. The development of rational methods, for environmental monitoring and for tracing sources of nuclear and radioactive materials in the environment, is constantly required.

    Traditionally, the actinides have been determined by radiometric techniques. These analyses can be time consuming for elements at low concentrations and with long half-lives. This thesis addresses the determination of actinides, especially plutonium, in environmental samples with ICP-QMS (inductively coupled plasma quadrupole mass spectrometry). The ICP-QMS instrument was equipped with an USN (ultrasonic nebuliser), which proved to be a successful combination for the determination of plutonium at low concentrations in acidified solutions after separation with anion exchange. The detection limit for plutonium was in the range 10-30 pg/l with a RSD of 1-10%. The suitability of chemical separation was evaluated for anion exchange, liquid-liquid-extraction and extraction chromatography.

    The outlined procedure, including sample dissolution, chemical separation and analysis, for determination of actinides in environmental matrices proved to be accurate and reliable. Quality assurance of the procedure was performed during an intercomparison exercise and with reference materials. The detection accuracy has also been validated with α-spectrometry and ICP-SFMS. The procedure has been applied to saline sediments and fresh water sediments as well as several fresh water matrices.

    List of papers
    1. Determination of plutonium in environmental samples with quadrupole ICP-MS
    Open this publication in new window or tab >>Determination of plutonium in environmental samples with quadrupole ICP-MS
    Show others...
    2008 (English)In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 275, no 1, p. 55-70Article in journal (Refereed) Published
    Abstract [en]

    A method for rapid determination of plutonium isotopes in environmental samples with ultrasonic nebulisation and quadrupole ICP-MS detection was established. Techniques for sample dissolution, pre-concentration and chemical separation were evaluated and the optimal scheme outlined. Comparisons with α-spectrometry and high resolution ICP-MS confirmed the suitability of the method when applied to different environmental matrices within the global fallout concentration range in the northern hemisphere as well as more contaminated sites. Operational detection limits were 0.5–1.5 fg/l for fresh waters and 0.03–0.1 ng/kg for lake sediments and saline marsh sediments.

    Place, publisher, year, edition, pages
    Berlin: Springer, 2008
    National Category
    Other Basic Medicine Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3231 (URN)10.1007/s10967-006-7004-z (DOI)000251867200007 ()2-s2.0-37549053953 (Scopus ID)
    Available from: 2007-02-13 Created: 2007-02-13 Last updated: 2018-01-13Bibliographically approved
    2. Rapid method for ICP-MS analysis of plutonium in sediment samples
    Open this publication in new window or tab >>Rapid method for ICP-MS analysis of plutonium in sediment samples
    Show others...
    2004 (English)Manuscript (preprint) (Other academic)
    National Category
    Chemical Sciences Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3232 (URN)
    Available from: 2007-02-13 Created: 2007-02-13 Last updated: 2017-10-18Bibliographically approved
    3. Redistribution pf Pu, Am, Cs and Np in salt marsh sediment - Wigtown Merse, Irish Sea
    Open this publication in new window or tab >>Redistribution pf Pu, Am, Cs and Np in salt marsh sediment - Wigtown Merse, Irish Sea
    Show others...
    (English)Manuscript (Other academic)
    National Category
    Chemical Sciences Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3233 (URN)
    Available from: 2007-02-13 Created: 2007-02-13 Last updated: 2017-10-18Bibliographically approved
    4. Plutonium remobilization in a humic-rich lake
    Open this publication in new window or tab >>Plutonium remobilization in a humic-rich lake
    Show others...
    2007 (English)In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 277, no 1, p. 265-268Article in journal (Refereed) Published
    Abstract [en]

    Fresh water from Lake Svartsjön, Sweden, was collected and four fractions were prepared: (1) adsorption on DEAE, (2) flocculation with Ca2+, (3) co-precipitation with Fe hydrous oxide and (4) co-precipitation with Mn hydrous oxide. The plutonium level in the lake is 65 fg/l (222 μBq/l), measured by ICP-QMS and ICP-SFMS. Pronounced accumulation in fractions (1) (34%) and (2) (66%), combined with observed levels of organic matter indicate that plutonium is predominantly associated with organic matter. Measurements of isotopic ratios indicate that 77% of the plutonium originates from weapons testing and the remaining appears to originate from the Chernobyl accident.

    National Category
    Environmental Sciences Chemical Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3234 (URN)10.1007/s10967-008-0741-4 (DOI)000257318800041 ()2-s2.0-46449100013 (Scopus ID)
    Available from: 2007-02-13 Created: 2007-02-13 Last updated: 2017-12-14Bibliographically approved
    5. Failure of 137Cs and 239,240Pu dating of lake sediments: fallout from nuclear weapons testing, the Chernobyl accident and redistribution processes?
    Open this publication in new window or tab >>Failure of 137Cs and 239,240Pu dating of lake sediments: fallout from nuclear weapons testing, the Chernobyl accident and redistribution processes?
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-3235 (URN)
    Available from: 2007-02-13 Created: 2007-02-13 Last updated: 2017-10-18Bibliographically approved
  • 99.
    Greis, Christina
    et al.
    Örebro University, Department of Natural Sciences.
    Duker, Anders
    Man-Technology-Environment Research Centre, Örebro University, Örebro, Sweden.
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Roos, Per
    Department of Radiation Physics, Lund University Hospital, Lund, Sweden; Risø National Laboratory, Roskilde, Denmark.
    Holm, Elis
    Department of Radiation Physics, Lund University Hospital, Lund, Sweden; .
    Plutonium remobilization in a humic-rich lake2007In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 277, no 1, p. 265-268Article in journal (Refereed)
    Abstract [en]

    Fresh water from Lake Svartsjön, Sweden, was collected and four fractions were prepared: (1) adsorption on DEAE, (2) flocculation with Ca2+, (3) co-precipitation with Fe hydrous oxide and (4) co-precipitation with Mn hydrous oxide. The plutonium level in the lake is 65 fg/l (222 μBq/l), measured by ICP-QMS and ICP-SFMS. Pronounced accumulation in fractions (1) (34%) and (2) (66%), combined with observed levels of organic matter indicate that plutonium is predominantly associated with organic matter. Measurements of isotopic ratios indicate that 77% of the plutonium originates from weapons testing and the remaining appears to originate from the Chernobyl accident.

  • 100.
    Greis, Christina
    et al.
    Örebro University, Department of Natural Sciences.
    Düker, Anders
    Pettersson, Håkan
    Karlsson, Stefan
    Allard, Bert
    Rapid method for ICP-MS analysis of plutonium in sediment samples2004Manuscript (preprint) (Other academic)
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