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  • 1551.
    Salihovic, Samira
    et al.
    Örebro University, School of Science and Technology.
    Kärrman, Anna
    Örebro University, School of Science and Technology.
    Lindström, Gunilla
    Örebro University, School of Science and Technology.
    Lind, P. Monica
    Lind, Lars
    van Bavel, Bert
    Örebro University, School of Science and Technology.
    A rapid method for the determination of perfluoroalkyl substances including structural isomers of perfluorooctane sulfonic acid in human serum using 96-well plates and column-switching ultra-high performance liquid chromatography tandem mass spectrometry2013In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1305, p. 164-170Article in journal (Refereed)
    Abstract [en]

    To facilitate high-throughput analysis suitable for large epidemiological studies we developed an automated column-switching ultra-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for determination of perfluorocarboxylic acids (PFCAs; C-5, C-6, C-7, C-8, C-9, C-10, C-11, C-12, and C-13), perfluoroalkyl sulfonic acids (PFSAs; C-4, C-6, C-8, and C-10), perfluorooctane sulfonamide (PFOSA), and five groups of structural perfluorooctane sulfonic acid (PFOS) isomers in human serum or plasma. The analytical procedure involves rapid protein precipitation using 96-well plates followed by an automated sample clean-up using an on-line trap column removing many potentially interfering sample components while through the mobile phase gradient the target analytes are eluted onto the analytical column for further separation and subsequent mass detection. The method was linear (R-2 <0.995) at concentrations ranging from 0.01 to 60 ng mL(-1) with method detection limits ranging between 0.01 and 0.17 ng mL(-1) depending on the analyte. The developed method was precise, with repeatability (n = 7) and reproducibility (n =103) coefficients of variation between 2% and 20% for most compounds including PFOS (2% and 8%) and its structural isomers (2-6% and 4-8%). The method was in conformity with a standard reference material. The column-switching HPLC-MS/MS method has been successfully applied for the determination of perfluoroalkyl substances including structural PFOS isomers in human plasma from an epidemiological study.

  • 1552.
    Salihovic, Samira
    et al.
    Örebro University, School of Science and Technology.
    Lampa, Erik
    Lindström, Gunilla
    Örebro University, School of Science and Technology.
    Lind, Lars
    Lind, P. Monica
    van Bavel, Bert
    Örebro University, School of Science and Technology.
    Circulating levels of Persistent Organic Pollutants (POPs) among elderly men and women from Sweden: results from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS)2012In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 44, p. 59-67Article in journal (Refereed)
    Abstract [en]

    Persistent Organic Pollutants (POPs) are a huge group of chemicals that have been linked to various adverse health effects in humans. Large epidemiological studies investigating gender differences in levels of POPs in the elderly are limited and the results from these are not always consistent. The present study was undertaken to examine the background levels of a broad range of POPs in human plasma samples among elderly men and women from Sweden and to assess the influence of gender. Levels of 23 POPs were determined in plasma samples collected during 2001-2004 from 1016 (50.2% women) 70year-old participants from the population-based Prospective Study of the Vasculature in Uppsala Seniors (PIVUS). Measurements were performed using high resolution gas chromatography with high resolution mass spectrometry (HRGC-HRMS) and the POPs studied were 16 polychlorinated biphenyls (PCBs), five organochlorine (OC) pesticides, one dioxin, and one brominated flame retardant. The concentrations of the selected POPs were found similar, or comparable, to other studies of non-occupationally exposed populations from Sweden and Europe. Differences in levels of POPs between men and women were assessed by using Wilcoxon rank-sum (Mann-Whitney) test. Significant (p<0.0001) gender differences in levels of specific POPs were observed and a number of POP concentrations were found to differ between men and women. More specifically, levels of HCB, OCDD, and PCB congeners #74, #105, and #118 were found to be higher in women, while the rest of the majority of POPs were higher in men.

  • 1553.
    Salihovic, Samira
    et al.
    Örebro University, School of Science and Technology.
    Mattioli, Lisa
    Lindström, Gunilla
    Örebro University, School of Science and Technology.
    Lind, Lars
    Lind, P. Monica
    van Bavel, Bert
    Örebro University, School of Science and Technology.
    A rapid method for screening of the Stockholm Convention POPs in small amounts of human plasma using SPE and HRGC/HRMS2012In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 86, no 7, p. 747-753Article in journal (Refereed)
    Abstract [en]

    A rapid analytical screening method allowing simultaneous analysis of 23 persistent organic pollutants (POPs) in human plasma was developed. Sample preparation based on solid-phase extraction (SPE) with additional clean-up using small multilayer silica gel columns. SPE was performed using a custom made polystyrene-divinylbenzene sorbent for the extraction of chlorinated and brominated POPs. Special efforts to reduce sample volume and improve speed and efficiency of the analytical procedure were made. Determination of 16 polychlorinated biphenyls (PCBs), 5 organochlorine (OC) pesticides, octachlorinated dibenzo-p-dioxin (OCDD) and polybrominated diphenyl ether (BDE #47) in 0.5 mL human plasma was performed by using high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC/HRMS). Recovery of POPs ranged between 46% and 110%, and reproducibility was below 25% relative standard deviation (RSD) for all target compounds, except for trans-nonachlor and OCDD, which were present only at low levels. Limits of detection (LOD) were for the PCBs between 0.8 and 117.7 pg mL(-1) plasma and for the OC pesticides between 5.9 and 89.1 pg mL(-1) plasma. The LOD for OCDD and BDE #47 were 1.4 pg mL(-1) plasma, and 9.2 pg mL(-1) plasma, respectively. The presented method was successfully applied to 1016 human plasma samples from an epidemiological study on cardiovascular disease. (C) 2011 Elsevier Ltd. All rights reserved.

  • 1554.
    Salihovic, Samira
    et al.
    Örebro University, School of Science and Technology.
    Nilsson, Helena
    Örebro University, School of Science and Technology.
    Hagberg, Jessika
    Örebro University, School of Science and Technology.
    Lindström, Gunilla
    Örebro University, School of Science and Technology.
    Trends in the analysis of persistent organic pollutants (POPs) in human blood2013In: TrAC. Trends in analytical chemistry, ISSN 0165-9936, E-ISSN 1879-3142, Vol. 46, p. 129-138Article in journal (Refereed)
    Abstract [en]

    The general demands on analytical practices in laboratories involved in monitoring concentrations of persistent organic pollutants (POPs) in human blood in the context of the Stockholm Convention are met by the validated analytical procedures applied in most laboratories today. At the same time, as the concentrations of many of the legacy POPs are decreasing in the general populations, more specific, sensitive, and accurate analytical techniques are required. Thus, a challenge for the Stockholm Convention is the analytical capacity, in terms of quality and availability worldwide, to monitor declining concentrations of POPs in human blood. However, other POP issues (e.g., those targeted by epidemiological studies) might require different information and therefore more specialized analytical procedures having greater instrumental sensitivity.

    We review current and emerging analytical procedures used for analysis of the chlorinated, brominated, and fluorinated classes of POPs in human blood with a focus on the compounds included in the Stockholm Convention. In general, analytical trends in sample clean-up, separation, detection techniques and quality protocols provide a tool for POP laboratories to measure POPs in human blood. Techniques based on established mass-selective instruments are most commonly employed but declining concentrations in humans in the future might require more selective, more sensitive techniques.

  • 1555.
    Salihovic, Samira
    et al.
    Örebro University, School of Science and Technology. Department of Medical Sciences and Science for Life Laboratory, Molecular Epidemiology Unit, Uppsala University, Uppsala, Sweden.
    Stubleski, Jordan
    Örebro University, School of Science and Technology.
    Kärrman, Anna
    Örebro University, School of Science and Technology.
    Larsson, Anders
    Department of Clinical Chemistry, Uppsala University, Uppsala, Sweden.
    Fall, Tove
    Department of Medical Sciences and Science for Life Laboratory, Molecular Epidemiology Unit, Uppsala University, Uppsala, Sweden.
    Lind, Lars
    Department of Medical Sciences, Cardiovascular Epidemiology, Uppsala University, Uppsala, Sweden.
    Lind, P. Monica
    Department of Medical Sciences, Occupational and Environmental Medicine, Uppsala University, Uppsala, Sweden.
    Changes in markers of liver function in relation to changes in perfluoroalkyl substances - A longitudinal study.: A longitudinal study2018In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 117, p. 196-203Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: While it is known that perfluoroalkyl substances (PFASs) induce liver toxicity in experimental studies, the evidence of an association in humans is inconsistent.

    OBJECTIVE: The main aim of the present study was to examine the association of PFAS concentrations and markers of liver function using panel data.

    METHODS: We investigated 1002 individuals from Sweden (50% women) at ages 70, 75 and 80 in 2001-2014. Eight PFASs were measured in plasma using isotope dilution ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). Bilirubin and hepatic enzymes alanine aminotransferase (ALT), alkaline phosphatase (ALP), and γ-glutamyltransferase (GGT) were determined in serum using an immunoassay methodology. Mixed-effects linear regression models were used to examine the relationship between the changes in markers of liver function and changes in PFAS levels.

    RESULTS:  = 0.11, 95% CI 0.06-0.15.

    CONCLUSION: Our longitudinal assessment established associations between changes in markers of liver function and changes in plasma PFAS concentrations. These findings suggest a relationship between low-dose background PFAS exposure and altered liver function in the general population.

  • 1556.
    Samadi, Mahnaz
    et al.
    Örebro University, School of Science and Technology.
    Stranneby, Dag
    Örebro University, School of Science and Technology.
    Connectionless Testing2005Conference paper (Other academic)
  • 1557.
    Samadi, Mahnaz
    et al.
    Örebro University, School of Science and Technology.
    Stranneby, Dag
    Örebro University, School of Science and Technology.
    Electromagnetic signatures for Test and Troubleshooting2003Conference paper (Other academic)
  • 1558.
    Samuel, Baiye Tanyi
    Örebro University, School of Science and Technology.
    Analysis of Mutations and Polymorphisms in PIk3CA, EGFR and MDM2 rs22797442012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 1559.
    Sand Ekmark, Fredrik
    Örebro University, School of Science and Technology.
    Screening for Cryptosporidium and Coliforms from Waters around Östersund and Åre2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 1560.
    Sandin, Patrik
    et al.
    Örebro University, School of Science and Technology.
    Ögren, Magnus
    Örebro University, School of Science and Technology.
    Gulliksson, Mårten
    Örebro University, School of Science and Technology. Univ Orebro, Sch Sci & Technol, S-70182 Orebro, Sweden..
    Numerical solution of the stationary multicomponent nonlinear Schrodinger equation with a constraint on the angular momentum2016In: Physical Review E, ISSN 2470-0045, Vol. 93, no 3, article id 033301Article in journal (Refereed)
    Abstract [en]

    We formulate a damped oscillating particle method to solve the stationary nonlinear Schrodinger equation (NLSE). The ground-state solutions are found by a converging damped oscillating evolution equation that can be discretized with symplectic numerical techniques. The method is demonstrated for three different cases: for the single-component NLSE with an attractive self-interaction, for the single-component NLSE with a repulsive self-interaction and a constraint on the angular momentum, and for the two-component NLSE with a constraint on the total angular momentum. We reproduce the so-called yrast curve for the single-component case, described in [A. D. Jackson et al., Europhys. Lett. 95, 30002 (2011)], and produce for the first time an analogous curve for the two-component NLSE. The numerical results are compared with analytic solutions and competing numerical methods. Our method is well suited to handle a large class of equations and can easily be adapted to further constraints and components.

  • 1561.
    Sandin, Patrik
    et al.
    Örebro University, School of Science and Technology.
    Ögren, Magnus
    Örebro University, School of Science and Technology.
    Gulliksson, Mårten
    Örebro University, School of Science and Technology.
    Smyrnakis, J.
    Technological Education Institute of Crete, Heraklion, Greece.
    Magiropoulos, M.
    Technological Education Institute of Crete, Heraklion, Greece.
    Kavoulakis, G. M.
    Technological Education Institute of Crete, Heraklion, Greece.
    Dimensional reduction in Bose-Einstein condensed clouds of atoms confined in tight potentials of any geometry and any interaction strength2017In: Physical Review E, ISSN 2470-0045, Vol. 95, no 1, article id 012142Article in journal (Refereed)
    Abstract [en]

    Motivated by numerous experiments on Bose-Einstein condensed atoms which have been performed in tight trapping potentials of various geometries (elongated and/or toroidal/annular), we develop a general method which allows us to reduce the corresponding three-dimensional Gross-Pitaevskii equation for the order parameter into an effectively one-dimensional equation, taking into account the interactions (i.e., treating the width of the transverse profile variationally) and the curvature of the trapping potential. As an application of our model we consider atoms which rotate in a toroidal trapping potential. We evaluate the state of lowest energy for a fixed value of the angular momentum within various approximations of the effectively one-dimensional model and compare our results with the full solution of the three-dimensional problem, thus getting evidence for the accuracy of our model.

  • 1562. Sanfeliu, Alberto
    et al.
    Hagita, Norihiro
    Saffiotti, Alessandro
    Örebro University, School of Science and Technology.
    Special issue: Network robot systems2008In: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 56, no 10, p. 791-791Article in journal (Refereed)
  • 1563.
    Saqib, Naeem
    Örebro University, School of Science and Technology.
    Distribution and chemical association of trace elements in incinerator residues and mining waste from a leaching perspective2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Incineration is a mainstream strategy for solid waste management in Sweden and all over the world. Improved knowledge and understanding about the distribution of trace elements (in ashes) during incineration, and how trace element partitioning respond to the changes in waste composition, are important in terms of combustion process optimization and plant efficiency. Moreover, determination of chemical association of trace elements in ashes are vital for avoiding environmental concerns and to promote possible reuse. In this study, partitioning of trace elements in ashes during incineration as function of input waste fuel and incineration technology was investigated. Further, chemical association of trace elements in resulting ashes was studied. An evaluation was also performed about feasibility of metal extraction from sulfidic mining waste and flotation tailings. Moreover, green liquor dreg (GLD) was tested with respect to stabilization of metals within the sulfidic mining waste.

    Findings showed that the total input of trace elements and chlorine affects the partitioning and increasing chlorine in the input waste caused increase in transfer of trace elements to fly ash especially for lead and zinc. Vaporization, condensation on fly ash particles and adsorption mechanisms play an important role for metal distribution. Firing mixed waste, especially biofuel mix, in grate or fluidized (CFB) boilers caused increased transfer into fly ash for almost all trace elements particularly lead and zinc. Possible reasons might be either an increased input concentration of respective element in the waste fuel, or a change in volatilization behavior due to the addition of certain waste fractions. Chemical association study for fly ashes indicated that overall, Cd, Pb, Zn, Cu and Sb are presenting major risk in most of the fly ashes, while in bottom ashes, most of elements are associated with stable fraction. Further, fuel type affects the association of elements in ashes. Chemical leaching of mining waste materials showed that sulfuric acid (under different conditions) is the best reagent to recover zinc and copper from sulfidic mining waste and also copper from flotation tailings. GLD indicates potential for metal stabilization in mining waste by reducing the metal mobility. Extraction methods could be applied to treat mining waste in order to meet the regulatory level at a specific mining site.Similarly stabilization/solidification  methods might be applied after leaching for recovery of metals.

    List of papers
    1. Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature
    Open this publication in new window or tab >>Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature
    2014 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 34, no 12, p. 2505-2519Article in journal (Refereed) Published
    Abstract [en]

    Trace element partitioning in solid waste (household waste, industrial waste, waste wood chips and waste mixtures) incineration residues was investigated. Samples of fly ash and bottom ash were collected from six incineration facilities across Sweden including two grate fired and four fluidized bed incinerators, to have a variation in the input fuel composition (from pure biofuel to mixture of waste) and different temperature boiler conditions. As trace element concentrations in the input waste at the same facilities have already been analyzed, the present study focuses on the concentration of trace elements in the waste fuel, their distribution in the incineration residues with respect to chlorine content of waste and combustion temperature. Results indicate that Zn, Cu and Pb are dominating trace elements in the waste fuel. Highly volatile elements mercury and cadmium are mainly found in fly ash in all cases; 2/3 of lead also end up in fly ash while Zn, As and Sb show a large variation in distribution with most of them residing in the fly ash. Lithophilic elements such as copper and chromium are mainly found in bottom ash from grate fired facilities while partition mostly into fly ash from fluidized bed incinerators, especially for plants fuelled by waste wood or ordinary wood chips. There is no specific correlation between input concentration of an element in the waste fuel and fraction partitioned to fly ash. Temperature and chlorine content have significant effects on partitioning characteristics by increasing the formation and vaporization of highly volatile metal chlorides. Zinc and cadmium concentrations in fly ash increase with the incineration temperature.

    Keywords
    Ash; Incineration residue; Solid waste management; Trace element partitioning
    National Category
    Chemical Sciences Environmental Sciences
    Research subject
    Chemistry; Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-41179 (URN)10.1016/j.wasman.2014.08.025 (DOI)000347019700009 ()25263218 (PubMedID)2-s2.0-84910639884 (Scopus ID)
    Available from: 2015-01-13 Created: 2015-01-13 Last updated: 2017-12-05Bibliographically approved
    2. Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies
    Open this publication in new window or tab >>Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies
    2015 (English)In: Journal of Environmental Sciences(China), ISSN 1001-0742, E-ISSN 1878-7320, Vol. 36, no 1 Oct., p. 9-21Article in journal (Refereed) Published
    Abstract [en]

    Impact of waste fuels (virgin/waste wood, mixed biofuel (peat, bark, wood chips) industrial, household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr, As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature. Total concentration in ashes decreased in order of Zn > Cu > Pb > Cr > Sb > As > Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers (especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions. Concentration levels in ash and ash matrix properties (association of elements on ash particles) are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in > 50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.

    Place, publisher, year, edition, pages
    Science Press, 2015
    Keywords
    Incineration residues; Leaching behavior; Biofuel incineration; Metal distribution; Waste incineration
    National Category
    Chemical Sciences
    Research subject
    Environmental Chemistry; Chemistry
    Identifiers
    urn:nbn:se:oru:diva-45103 (URN)10.1016/j.jes.2015.03.006 (DOI)000362983500002 ()26456601 (PubMedID)2-s2.0-84943225103 (Scopus ID)
    Note

    Funding Agency:

    Varmeforsk (Thermal Engineering Research Association) Q4-251

    Available from: 2015-07-04 Created: 2015-07-04 Last updated: 2017-12-04Bibliographically approved
    3. Chemical association and mobility of trace elements in 13 different fuel incineration fly ashes
    Open this publication in new window or tab >>Chemical association and mobility of trace elements in 13 different fuel incineration fly ashes
    2015 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 165, p. 193-204Article in journal (Refereed) Published
    Abstract [en]

    The migration of trace elements from waste incineration fly ash is problematic during utilization/ landfilling. This study investigated the chemical association and potential mobility of trace elements in fly ashes originating from incineration of different fuels [virgin wood, recovered waste wood (RWW), mixed wooden fuel/waste, household, industrial, and mixed waste]. Fly ashes were characterized for total content of trace elements, chemical association by sequential extraction and leaching behaviour by standard leaching method (EN 12457-3). Results showed that average total content of trace elements in 13 fly ashes decreased in the order Zn > Cu > Pb > Sb > Cr > As > Cd. Sequential extraction results indicated that overall, Cd, Pb, Zn, Cu and Sb were the most mobile elements and excessive leaching was associated with high content of acid exchangeable fractions. Sequential extraction showed thatthe average percentage of trace elements in labile and stable fractions for all 13 fly ashes decreased in the order:Cd > Cu > Sb > Zn > As > Pb > Cr (ion-exchangeable), Pb > Zn > Sb > Cd > Cu > As > Cr(acid soluble),Cr > As > Pb > Sb > Cu > Zn > Cd (residual). The standard leaching procedure of ashes indicated that the leached amount of Pb in all samples, Zn in 7 while Cu in 6 (out of 13) samples, respectively, exceeded the regulatory level for disposal. Moreover, principal component analysis (PCA) showed that fuel type affects the chemical association of trace elements in fly ash. Further, risk assessment code (RAC) suggested that most of fly ashes presented very high risk due to high RAC values for Cd, Zn, Cu and Sb.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    Chemical speciation; Fly ash; Risk assessment; Trace elements mobility; MSWI
    National Category
    Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-46305 (URN)10.1016/j.fuel.2015.10.062 (DOI)000364655000023 ()2-s2.0-84946087137 (Scopus ID)
    Available from: 2015-10-23 Created: 2015-10-23 Last updated: 2017-12-01Bibliographically approved
    4. Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes
    Open this publication in new window or tab >>Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes
    2016 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 172, p. 105-117Article in journal (Refereed) Published
    Abstract [en]

    The release of trace elements from waste incineration bottom ash is problematic during utilization/landfilling. Thirteen bottom ashes (from various waste fuels and wooden/mixed wooden fuel) were investigated with respect to the total content, leaching behaviour by standard leaching procedure (EN 12457-3), and chemical association of trace elements by sequential extraction. Results showed that the content of trace elements in household/or industrial waste bottom ashes were of high level in comparison to in wooden/mixed wooden fuel/mixed wooden waste ashes. Type of fuel being treated greatly impacts the total inventory of trace elements. On average, trace element content in 13 ashes followed the decreasing order; Cu > Zn > Pb > Cr > Ni > Sb > As. In this study the average total content of Zn, Pb, Cu and Cr was higher in grate bottom ash treating household/industrial waste in comparison to fluidized boilers ash using same waste, however, there were too few data points and variation in data was large. By Standard leaching procedure, an excessive amount (more than disposal limit) of leached Cr, Pb, Sb and Cu (mostly in household/industrial waste ash) was observed in 6, 5, 5 and 4 of the 13 samples, respectively. Correlation coefficients (r) found between total and water leachable contents for Cu, Sb and As were 0.8, 0.7 and 0.6 respectively. Sequential extraction indicated that residual was the major fraction mostly, however, considerable amounts of trace elements had the potential to leach out. A large fraction of arsenic (57% based on average values) in 5 samples (mostly in waste/virgin wood and mixed wooden waste/fuel) and Zn (49% based on average values) in 4 of 13 samples (mostly household/or industrial) were found in the fractions that are easily available (acid soluble and exchangeable). Further, a considerable amount of Cu in 4 samples were found associated with the organic-bound phase. Dissolved organic matter might play an important role in leaching of Cu during utilization/landfilling. Moreover, principal component analysis (PCA) showed that fuel type affects the association of trace elements in bottom ash. Amounts of labile trace elements in wooden/mixed wooden fuel/waste bottom ashes were comparatively lower than other fuel bottom ashes. None of the samples exceeded the limit of disposal with respect to DOC leaching while chlorine in two and sulphate in three samples (household/industrial) exceeded limit. LOI (550 °C) values were higher for bottom ash from grate facilities probably due to no-pre-treatment of the waste fuel. While comparatively low values of LOI (1 000 °C) in few samples implies that the oxidation might have outweighed the loss of carbonates.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keywords
    Bottom ash; Speciation; Trace elements; Incineration; Mobility
    National Category
    Inorganic Chemistry
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-47348 (URN)10.1016/j.fuel.2016.01.010 (DOI)000368881200013 ()2-s2.0-84954326717 (Scopus ID)
    Note

    Funding Agency:

    Varmeforsk (Thermal Engineering Research Association)

    Available from: 2016-01-07 Created: 2016-01-07 Last updated: 2017-12-01Bibliographically approved
    5. Chemical leaching of Zn, Cu and Pb from oxidized sulfidic mining waste followed by stabilization using green liquor dreg
    Open this publication in new window or tab >>Chemical leaching of Zn, Cu and Pb from oxidized sulfidic mining waste followed by stabilization using green liquor dreg
    (English)Manuscript (preprint) (Other academic)
    National Category
    Other Chemistry Topics
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-49743 (URN)
    Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2017-10-17Bibliographically approved
    6. Flotation tailings as a copper resource - Extraction and characterization through chemical leaching
    Open this publication in new window or tab >>Flotation tailings as a copper resource - Extraction and characterization through chemical leaching
    (English)Manuscript (preprint) (Other academic)
    National Category
    Other Chemistry Topics
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-49744 (URN)
    Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2017-10-17Bibliographically approved
  • 1564.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes2016In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 172, p. 105-117Article in journal (Refereed)
    Abstract [en]

    The release of trace elements from waste incineration bottom ash is problematic during utilization/landfilling. Thirteen bottom ashes (from various waste fuels and wooden/mixed wooden fuel) were investigated with respect to the total content, leaching behaviour by standard leaching procedure (EN 12457-3), and chemical association of trace elements by sequential extraction. Results showed that the content of trace elements in household/or industrial waste bottom ashes were of high level in comparison to in wooden/mixed wooden fuel/mixed wooden waste ashes. Type of fuel being treated greatly impacts the total inventory of trace elements. On average, trace element content in 13 ashes followed the decreasing order; Cu > Zn > Pb > Cr > Ni > Sb > As. In this study the average total content of Zn, Pb, Cu and Cr was higher in grate bottom ash treating household/industrial waste in comparison to fluidized boilers ash using same waste, however, there were too few data points and variation in data was large. By Standard leaching procedure, an excessive amount (more than disposal limit) of leached Cr, Pb, Sb and Cu (mostly in household/industrial waste ash) was observed in 6, 5, 5 and 4 of the 13 samples, respectively. Correlation coefficients (r) found between total and water leachable contents for Cu, Sb and As were 0.8, 0.7 and 0.6 respectively. Sequential extraction indicated that residual was the major fraction mostly, however, considerable amounts of trace elements had the potential to leach out. A large fraction of arsenic (57% based on average values) in 5 samples (mostly in waste/virgin wood and mixed wooden waste/fuel) and Zn (49% based on average values) in 4 of 13 samples (mostly household/or industrial) were found in the fractions that are easily available (acid soluble and exchangeable). Further, a considerable amount of Cu in 4 samples were found associated with the organic-bound phase. Dissolved organic matter might play an important role in leaching of Cu during utilization/landfilling. Moreover, principal component analysis (PCA) showed that fuel type affects the association of trace elements in bottom ash. Amounts of labile trace elements in wooden/mixed wooden fuel/waste bottom ashes were comparatively lower than other fuel bottom ashes. None of the samples exceeded the limit of disposal with respect to DOC leaching while chlorine in two and sulphate in three samples (household/industrial) exceeded limit. LOI (550 °C) values were higher for bottom ash from grate facilities probably due to no-pre-treatment of the waste fuel. While comparatively low values of LOI (1 000 °C) in few samples implies that the oxidation might have outweighed the loss of carbonates.

  • 1565.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical association and mobility of trace elements in 13 different fuel incineration fly ashes2015In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 165, p. 193-204Article in journal (Refereed)
    Abstract [en]

    The migration of trace elements from waste incineration fly ash is problematic during utilization/ landfilling. This study investigated the chemical association and potential mobility of trace elements in fly ashes originating from incineration of different fuels [virgin wood, recovered waste wood (RWW), mixed wooden fuel/waste, household, industrial, and mixed waste]. Fly ashes were characterized for total content of trace elements, chemical association by sequential extraction and leaching behaviour by standard leaching method (EN 12457-3). Results showed that average total content of trace elements in 13 fly ashes decreased in the order Zn > Cu > Pb > Sb > Cr > As > Cd. Sequential extraction results indicated that overall, Cd, Pb, Zn, Cu and Sb were the most mobile elements and excessive leaching was associated with high content of acid exchangeable fractions. Sequential extraction showed thatthe average percentage of trace elements in labile and stable fractions for all 13 fly ashes decreased in the order:Cd > Cu > Sb > Zn > As > Pb > Cr (ion-exchangeable), Pb > Zn > Sb > Cd > Cu > As > Cr(acid soluble),Cr > As > Pb > Sb > Cu > Zn > Cd (residual). The standard leaching procedure of ashes indicated that the leached amount of Pb in all samples, Zn in 7 while Cu in 6 (out of 13) samples, respectively, exceeded the regulatory level for disposal. Moreover, principal component analysis (PCA) showed that fuel type affects the chemical association of trace elements in fly ash. Further, risk assessment code (RAC) suggested that most of fly ashes presented very high risk due to high RAC values for Cd, Zn, Cu and Sb.

  • 1566.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies2015In: Journal of Environmental Sciences(China), ISSN 1001-0742, E-ISSN 1878-7320, Vol. 36, no 1 Oct., p. 9-21Article in journal (Refereed)
    Abstract [en]

    Impact of waste fuels (virgin/waste wood, mixed biofuel (peat, bark, wood chips) industrial, household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr, As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature. Total concentration in ashes decreased in order of Zn > Cu > Pb > Cr > Sb > As > Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers (especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions. Concentration levels in ash and ash matrix properties (association of elements on ash particles) are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in > 50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.

  • 1567.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Leaching of Zn, Cu and Pb from oxidised sulphidic mine waste as a function of temperature, L/S ratio and leaching reagents2013In: Goldschmidt, 2013Conference paper (Refereed)
  • 1568.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature2014In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 34, no 12, p. 2505-2519Article in journal (Refereed)
    Abstract [en]

    Trace element partitioning in solid waste (household waste, industrial waste, waste wood chips and waste mixtures) incineration residues was investigated. Samples of fly ash and bottom ash were collected from six incineration facilities across Sweden including two grate fired and four fluidized bed incinerators, to have a variation in the input fuel composition (from pure biofuel to mixture of waste) and different temperature boiler conditions. As trace element concentrations in the input waste at the same facilities have already been analyzed, the present study focuses on the concentration of trace elements in the waste fuel, their distribution in the incineration residues with respect to chlorine content of waste and combustion temperature. Results indicate that Zn, Cu and Pb are dominating trace elements in the waste fuel. Highly volatile elements mercury and cadmium are mainly found in fly ash in all cases; 2/3 of lead also end up in fly ash while Zn, As and Sb show a large variation in distribution with most of them residing in the fly ash. Lithophilic elements such as copper and chromium are mainly found in bottom ash from grate fired facilities while partition mostly into fly ash from fluidized bed incinerators, especially for plants fuelled by waste wood or ordinary wood chips. There is no specific correlation between input concentration of an element in the waste fuel and fraction partitioned to fly ash. Temperature and chlorine content have significant effects on partitioning characteristics by increasing the formation and vaporization of highly volatile metal chlorides. Zinc and cadmium concentrations in fly ash increase with the incineration temperature.

  • 1569.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Uranium in 31 Swedish ashes – differences between boiler type and fuels2015In: Uranium – Past and Future Challenges / [ed] Merkel, B.J. and Arab, A., Springer, 2015, p. 745-750Conference paper (Refereed)
    Abstract [en]

    From 14 Swedish boilers (grate fired as well as fluidized bed) 31 different ashes were collected and analysed for uranium. Uranium concentrations ranged from 0.32 to 22 mg/kg dw. Average uranium concentration in the bottom ash and fly ash was 1.3 and 2.7 mg/kg dw, respectively, indicating that uranium in the fuel is quite volatile during combustion. Highest concentration of uranium was found in a fly ash from a boiler burning peat indicating that peat is a natural source of uranium.

  • 1570.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Waste incineration: impact of input waste fuel composition on trace element distribution and chemical speciation in fly and bottom ashesArticle in journal (Refereed)
  • 1571.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Waste incineration: impact of input waste fuel composition on trace element distribution and chemical speciation in fly and bottom ashes2015Conference paper (Refereed)
    Abstract [en]

    Incineration process for waste to energy is a widely developed method for solid waste management in Sweden and all over the world. In addition to its unique benefits of mass and volume reduction of waste, it can also provide electricity and/or heat. In Sweden 48% of household waste, 40% of industrial waste and 75% of recovered waste wood (RWW) (construction and demolition) are treated through incineration. In order to avoid environmental concerns and operational problems posed by incineration by-products (fly ash, bottom ash), it is important to understand that how trace element partitioning respond to the changes in waste composition. In this study, Influence of input waste fuel composition and chlorine content on trace element distribution in solid waste (RWW, industrial waste, RWW mixed with bark & sludge and mixed household & industrial waste) incineration fly and bottom ashes were studied. Further, chemical speciation of trace elements in resulting fly/bottom ashes was investigated by sequential extraction. Results indicate that Zn, Cu, Pb and Cr are the dominating trace elements in the waste fuel and ashes. Most part of high and medium volatile trace elements such as Cd, Pb, Zn, Sb and As were transferred to fly ash for pure RWW / industrial waste incineration in fluidized boilers. Overall, As and Cd seems to show increased transfer to fly ash with the increase in input content of these elements in the waste fuel, while low volatiles Cu and Cr showed decrease in transfer to fly ash with input content. Overall, Cd was partitioned mostly in the fly ash in all cases during incineration, most probably because of vaporization, condensation on fly ash particles and adsorption mechanisms. While 2/3 or more of Zn and Pb also transferred to fly ash. Low volatiles Cu and Cr stayed mainly in the bottom ash except in a few fluidized boilers operation that might be attributed to particle entrainment or turbulence. Increased chlorine in the waste fuel feed increased the trace element transfer to fly ash especially for Zn and Pb by forming their metal chlorides that are highly volatile. Sequential extraction results and risk assessment code showed that Zn and Pb in RWW, Cd in industrial waste, Pb, Cu and Cd in mixed household/industrial waste while Zn, Cd in mixed biofuel waste fly ash were posing high risk to the environment on utilization/landfilling. Further speciation results indicated that in RWW bottom ash, arsenic was mainly (around 50%) present in mobile fractions (ion exchangeable and acid soluble). While in mixed household & industrial waste bottom ash, 65% of Cu was bound to the oxidizable fraction that indicates the role of organic matter on leaching. Moreover, bottom ash from incineration of industrial waste or mixed household/industrial waste contained higher amounts (as compared to biofuel incineration bottom ashes) of trace elements such as that of Zn, Cu, Cr and Sb in labile fractions An increased input concentration of certain trace elements, such as Zn when firing pure RWW or mixed biofuel and chlorine while firing mixed waste or industrial waste, caused increased concentration in fly ash. It might also boost the deposition and corrosion problems. So it is suggested to keep input metal content and chlorine concentrations as low as possible

  • 1572.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Sartz, Lotta
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical leaching of Zn, Cu and Pb from oxidized sulfidic mining waste followed by stabilization using green liquor dregManuscript (preprint) (Other academic)
  • 1573.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Sjöberg, Viktor
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Flotation tailings as a copper resource - Extraction and characterization through chemical leachingManuscript (preprint) (Other academic)
  • 1574.
    Sartz, Lotta
    et al.
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemistry and environmental science research as a part of education: An example from Sweden2014In: 1st International Congress and Exhibition on Current Trends on Science and Technology Education (SCITEED 2014) / [ed] Oral, A.Y. and Bahsi, Z.B., Curran Associates, Inc., 2014, p. 27-32Conference paper (Refereed)
  • 1575.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Development of a low-tech treatment for neutral mine water - a case study2016In: Mining Meets Water – Conflicts and Solutions: IMWA 2016 in Leipzig, Germany, July 11–15, 2016 / [ed] Drebenstedt, C. & Paul, M., Freiberg: TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering , 2016, p. 913-918Conference paper (Refereed)
    Abstract [en]

    Lovisagruvan is a Pb-Zn-Ag mine in mid-south Sweden, with a yearly production of some 40 000 tons. There are four main levels in the mine: 55, 105, 145 and 190 m below ground. Water is continously pumped at a rate of 5 m3/h, passing sedimentation pools at each of the four main levels in the mine and finally one above ground. A modified backfill mining is used and in order to visually separate the ore from the waste rock limestone is used as a separating layer. Limestone addition in combination with non-acid producing mineralisation generates a pH-neutral mine water. For many years the mine has had problems with high levels of zinc and lead in the mine water released to recipient. The primary contaminants, lead and zinc, were mainly found as particles or associated to particles. With a combination of several measures including a sandfilter and FeSO4 addition suspended matter was reduced 93 %, lead 91 % and zinc 71 %.

  • 1576.
    Sartz, Lotta
    et al.
    Bergskraft Bergslagen, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Impact of temperature on weathering rates: a long term kinetic study on waste rock from Bergslagen, Sweden2013In: Annual International Mine Water Association Conference: Reliable Mine Water Technology / [ed] Brown, A.; Figueroa, L. & Wolkersdorfer, Ch., Colorado, USA: IMWA , 2013, p. 463-469Conference paper (Refereed)
    Abstract [en]

    To assess the impact of different climatic conditions four weathering systems with waste rock from Bergslagen, Sweden, were followed. Secondary weathering products (ferrous and ferric sulphates and (oxy)hydroxides) on pyrite surfaces can slow down oxidation rates. It was investigated if repeated freezing/thawing could have an effect on the stability of the secondary product layer. After 90 weeks of weathering, freezing/thawing had not enhanced weathering rates, not even in combination with warm, humid air. Highest weathering rates were unexpectedly found in a reference system constantly kept at room temperature, and not in the more forceful humidity cell system.

  • 1577.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Reclamation of historical mine waste using alkaline by-products2007In: Northern Latitudes Mining Reclamation Workshop, Juneau, Alaska, USA, 15-17 May, 2007, 2007, p. 10 pages-Conference paper (Refereed)
  • 1578.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Treatment of Acidic and Neutral Metal-Laden Mine Waters with Bone Meal Filters2013In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 32, no 4, p. 293-301Article in journal (Refereed)
    Abstract [en]

    Bone meal was used to treat two different mine waters: acidic (pH 4.5) mine water containing high concentrations of Fe and Al and neutral/slightly alkaline (pH 7) mine water. Original primary contaminants in both waters were Pb and Zn. The contaminants were dissolved in the acidic mine water and mostly suspended in the neutral mine water. Flow through the filter treating the acidic mine water was relatively low (0.1 L/min), but increased towards the end of the test period. Removal of Pb and Cu was very good in the acidic mine water (around 80 %); removal of Zn was slightly less (60 %) due to the final pH (approximate to 6-6.5). Flow through the filter treating the neutral mine water was initially significantly higher (5 L/min) and the removal of Pb and Zn was less compared to the acidic mine water (50 % for Pb and 35 % for Zn). The major reason for the difference in metal removal in the two mine waters was the difference in Fe and Al sorption sites, flow rate, and pH; in order for the bone meal to dissolve and form metal phosphate, the pH has to be <7.

  • 1579.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Treatment of acidic and neutral metal-laden mine waters with bone meal filters2012In: Mine Water and the Environment / [ed] McCullough, C.D., Lund, M.A. and Wyse, L, International Mine Water Association (IMWA) , 2012, p. 643-650Conference paper (Refereed)
  • 1580.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sverige.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    On the neutralisation of ARD and acid generating waste rock by different alkalinity sources: carbonate and/or hydroxide2010In: Mine water & innovative thinking: proceedings 2010 / [ed] Wolkersdorfer, C. and Freund, A., Nova Scotia, Canada: Cape Breton University Press , 2010, p. 263-266Conference paper (Refereed)
    Abstract [en]

    Six alkaline waste materials were tested for their neutralising capacity and metal immobilisation ability as amendments to a weathered waste rock. Two of the materials were of carbonate-type: lime mud (LM) and green liquor dreg (GLD) and four were of hydroxide-type: lime kiln dust (LKD), LD-slag (LD), carbonated fly ash (CFA) and a fresh fly ash (FFA). pH achieved by carbonate and ARD reactions (approximately 6) is too low to ensure quantitative sorption of e.g. Zn and Cd. Hydroxide neutralisation reactions however result in higher pH, but lower alkalinity.

  • 1581.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Alkaline by-products as amendments for stabilization and neutralization of oxidized sulphidic mine waste deposits2010In: 34th British Columbia Mine Reclamation & 35th CLRA/ACRSD National Conference, 2010, p. 10 pages-Conference paper (Refereed)
    Abstract [en]

    Stabilization of oxidized sulphidic mine waste deposits with alkaline by-products could be a way of controlling ARD. Mixtures of alkaline by-products (10% by volume) and oxidized waste rock have been studied during six months in 30 L experimental drums. Alkaline by-products are: lime mud (LM), green liquor dreg (GLD), lime kiln dust (LKD), LD slag (LD), water work granules (WWG), carbonized fly ash (FAE) and fresh fly ash (FAF). The experiments are fed with water once a week to imitate natural precipitation.

    pH of the reference (no alkaline amendment) is below 3 and trace metal concentrations are 2000 mg/l, 4 mg/l and 1 mg/l for Zn, Cd and Pb respectively. LKD, LM and LD amended systems (pH 6.7-7.5) are the most efficient for Cd- and Zn-removal (reduction at least 99 % compared to the reference), while GLD (tap pH 6.5) is the most efficient for Pb-removal (99 % reduction compared to the reference). FAE amended system only reaches pH around 5 and accordingly trace metal reduction is rather low. Geochemical simulations using PHREEQC indicate equilibrium with otavite and smithsonite in the WWG and GLD systems, whereas cerrusite is at equilibrium in the LKD, WWG and GLD systems.

  • 1582.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    From bench to field: A stepwise method towards full scale remediation of historic mine sites2009In: 8th International Conference on Acid Rock Drainage (ICARD) and Securing the Future: Mining, Metals & the Environment in a Sustainable Society 2009, 2009, p. 1207-1216Conference paper (Refereed)
  • 1583.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Mixing of acid rock drainage with alkaline leachates: Formation of solid precipitates and pH-buffering2016In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 35, no 1, p. 64-76Article in journal (Refereed)
    Abstract [en]

    Three metal-rich, acidic mine waters (from Bersbo and Ljusnarsberg, Sweden) were mixed with alkaline fly ash leachates in various proportions, representing a pH titration. Changes in pH and the loss of metals in solution due to precipitation of solid phases were tracked. Mineral equilibria and changes in pH and alkalinity were simulated using the geochemical code PHREEQC and the MINTEQv4 database, and the measured and simulated pH responses were compared. The formation of solid precipitates corresponded to fairly well-defined pH-buffering regions, reflecting the mine water compositions (notably the levels of Fe, Al, and Mn). Zn precipitation had a distinct buffering effect at near-neutral pH for the mine waters not dominated by iron. The formation of solid Mg phases (carbonate, as well as hydroxide) was indicated at high pH (above 9), but not formation of solid Ca phases, despite high sulfate levels. The phases that precipitated were various amorphous mixtures, mostly of the metals Fe, Al, Mn, Zn, and Mg. For the Fe-rich mine water, pH was poorly simulated with a simple MIX model, while alkalinity predictions agreed reasonably well with measured data. For the Al-rich mine waters, the simulated pH responses agreed well with the measurements. In an additional step, geochemical simulations were performed where selected proxy phases for major elements were forced to precipitate; this significantly improved the pH and alkalinity predictions. This approach may be more efficient than performing mixing experiments and titrations.

  • 1584.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Stabilisation of acid-generating waste rock with alkaline by-products: Results from a meso-scale experiment2009In: Securing the Future and 8th ICARD, 2009, p. 10 pages-Conference paper (Refereed)
  • 1585.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kumla, Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Alkaline by-products to ameliorate oxidized sulphidic mine waste and ARD2010In: Proc. EU Mine Drainage Research Exchange Conf. PADRE, June 11, Freiberg, Germany, 2010, p. 1 p-Conference paper (Refereed)
  • 1586.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Applicability and suitability of different alkaline by-products in historic mine sites remediation2012In: 9th International Conference on Acid Rock Drainage (ICARD 2012) / [ed] Price, W.A., Hogan, C. and Tremblay, G., Mine Environment Neutral Drainage ( MEND ) , 2012, p. 682-693Conference paper (Refereed)
  • 1587.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Larsson, Erik
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Alkaline treatment of ARD: carbonate and hydroxide alkalinities in sequence2012In: 9th International Conference on Acid Rock Drainage (ICARD 2012) / [ed] Price, W.A., Hogan, C. and Tremblay, G, Ontario, Kanada: Golder Associates Ltd. , 2012, p. 78-88Conference paper (Refereed)
  • 1588.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Larsson, Erik
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Weathering of waste rock in different climatic conditions: A kinetic freeze/thaw and humidity cell experiment2011In: Mine water: Managing the challenges: proceedings of the International Mine Water Association Congress 2011 / [ed] Rüde, T.R., Freund, A. and Wolkersdorfer, C., Aachen: RWTH , 2011, p. 453-456Conference paper (Refereed)
    Abstract [en]

    Ferrous and ferric sulphates and (oxy)hydroxides can grow on pyrite surfaces and slow oxidationrates. However, in northern climates, repeated freeze/thaw cycles can cause cracks, channeling and exposureof new surfaces. In the present study, weathering in a repeated freeze/thaw experiment was compared to aregular humidity cell experiment. Introductory results (after 17 weeks) show very small changes in pH for thefreeze/thaw system (pH around 5), while pH in reference and humidity cell systems decreased rapidly thefirst weeks (to around 4). An increase in electrical conductivity, sulphate and major ions was noticed in thetwo latter systems.

  • 1589.
    Sathyakeerthy, Subhash
    et al.
    Örebro University, School of Science and Technology.
    Di Rocco, Maurizio
    Örebro University, School of Science and Technology.
    Pecora, Federico
    Örebro University, School of Science and Technology.
    Saffiotti, Alessandro
    Örebro University, School of Science and Technology.
    Scaling up ubiquitous robotic systems from home to town (and beyond)2013In: UbiComp '13 Adjunct Proceedings of the 2013 ACM conference on Pervasive and ubiquitous computing adjunct publication, Association for Computing Machinery (ACM), 2013, p. 107-110Conference paper (Refereed)
  • 1590.
    Sayin, Sama I.
    et al.
    Department of Molecular and Clinical Medicine, Sahlgrenska Center for Cardiovascular and Metabolic Research, University of Gothenburg, Gothenburg, Sweden.
    Wahlström, Annika
    Department of Molecular and Clinical Medicine, Sahlgrenska Center for Cardiovascular and Metabolic Research, University of Gothenburg, Gothenburg, Sweden.
    Felin, Jenny
    Department of Molecular and Clinical Medicine, Sahlgrenska Center for Cardiovascular and Metabolic Research, University of Gothenburg, Gothenburg, Sweden.
    Jäntti, Sirkku
    VTT Technical Research Centre of Finland, Espoo, Finland.
    Marschall, Hanns-Ulrich
    Department of Molecular and Clinical Medicine, Sahlgrenska Center for Cardiovascular and Metabolic Research, University of Gothenburg, Gothenburg, Sweden.
    Bamberg, Krister
    AstraZeneca R and D Mölndal, Mölndal, Sweden.
    Angelin, Bo
    Department of Endocrinology, Metabolism and Diabetes, Karolinska Institute, Karolinska University Hospital Huddinge, Stockholm, Sweden.
    Hyötyläinen, Tuulia
    Örebro University, School of Science and Technology. VTT Technical Research Centre of Finland, Espoo, Finland.
    Oresic, Matej
    Örebro University, School of Medical Sciences. VTT Technical Research Centre of Finland, Espoo, Finland.
    Bäckhed, Fredrik
    Department of Molecular and Clinical Medicine, Sahlgrenska Center for Cardiovascular and Metabolic Research, University of Gothenburg, Gothenburg, Sweden; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
    Gut microbiota regulates bile acid metabolism by reducing the levels of tauro-beta-muricholic acid, a naturally occurring FXR antagonist2013In: Cell Metabolism, ISSN 1550-4131, E-ISSN 1932-7420, Vol. 17, no 2, p. 225-235, article id S1550-4131(13)00011-9Article in journal (Refereed)
    Abstract [en]

    Bile acids are synthesized from cholesterol in the liver and further metabolized by the gut microbiota into secondary bile acids. Bile acid synthesis is under negative feedback control through activation of the nuclear receptor farnesoid X receptor (FXR) in the ileum and liver. Here we profiled the bile acid composition throughout the enterohepatic system in germ-free (GF) and conventionally raised (CONV-R) mice. We confirmed a dramatic reduction in muricholic acid, but not cholic acid, levels in CONV-R mice. Rederivation of Fxr-deficient mice as GF demonstrated that the gut microbiota regulated expression of fibroblast growth factor 15 in the ileum and cholesterol 7α-hydroxylase (CYP7A1) in the liver by FXR-dependent mechanisms. Importantly, we identified tauro-conjugated beta- and alpha-muricholic acids as FXR antagonists. These studies suggest that the gut microbiota not only regulates secondary bile acid metabolism but also inhibits bile acid synthesis in the liver by alleviating FXR inhibition in the ileum.

  • 1591.
    Schabert, Antek
    Örebro University, School of Science and Technology.
    Integrating the use of prior information into Graph-SLAM with NDTregistration for loop detection2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 1592.
    Schaffernicht, Erik
    et al.
    Örebro University, School of Science and Technology.
    Hernandez Bennetts, Victor
    Örebro University, School of Science and Technology.
    Lilienthal, Achim
    Örebro University, School of Science and Technology.
    Mobile robots for learning spatio-temporal interpolation models in sensor networks - The Echo State map approach: The Echo State map approach2017In: 2017 IEEE International Conference on Robotics and Automation (ICRA), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 2659-2665Conference paper (Refereed)
    Abstract [en]

    Sensor networks have limited capabilities to model complex phenomena occuring between sensing nodes. Mobile robots can be used to close this gap and learn local interpolation models. In this paper, we utilize Echo State Networks in order to learn the calibration and interpolation model between sensor nodes using measurements collected by a mobile robot. The use of Echo State Networks allows to deal with temporal dependencies implicitly, while the spatial mapping with a Gaussian Process estimator exploits the fact that Echo State Networks learn linear combinations of complex temporal dynamics. The resulting Echo State Map elegantly combines spatial and temporal cues into a single representation. We showcase the method in the exposure modeling task of building dust distribution maps for foundries, a challenge which is of great interest to occupational health researchers. Results from simulated data and real world experiments highlight the potential of Echo State Maps. While we focus on particulate matter measurements, the method can be applied for any other environmental variables like temperature or gas concentration.

  • 1593.
    Schaffernicht, Erik
    et al.
    Örebro University, School of Science and Technology.
    Trincavelli, Marco
    Örebro University, School of Science and Technology.
    Lilienthal, Achim J.
    Örebro University, School of Science and Technology.
    Bayesian Spatial Event Distribution Grid Maps for Modeling the Spatial Distribution of Gas Detection Events2014In: Sensor Letters, ISSN 1546-198X, E-ISSN 1546-1971, Vol. 12, no 6-7, p. 1142-1146Article in journal (Refereed)
    Abstract [en]

    In this paper we introduce a novel gas distribution mapping algorithm, Bayesian Spatial Event Distribution (BASED), that, instead of modeling the spatial distribution of a quasi-continuous gas concentration, models the spatial distribution of gas events, for example detection and non-detection of a target gas. The proposed algorithm is based on the Bayesian Inference framework and models the likelihood of events at a certain location with a Bernoulli distribution. In order to avoid overfitting, a Bayesian approach is used with a beta distribution prior for the parameter μ that governs the Bernoulli distribution. In this way, the posterior distribution maintains the same form of the prior, i.e., will be a beta distribution as well, enabling a simple approach for sequential learning. To learn a map composed of beta distributions, we discretize the inspection area into a grid and extrapolate from local measurements using Gaussian kernels. We demonstrate the proposed algorithm for MOX sensors and a photo ionization detector mounted on a mobile robot and show how qualitatively similar maps are obtained from very different gas sensors.

  • 1594.
    Schellwat, Holger
    Örebro University, School of Science and Technology. Universidade Eduardo Mondlane, Mocambique.
    A Gentle Introduction to a Beautiful Theorem of Molien2017Report (Other (popular science, discussion, etc.))
    Abstract [en]

    The purpose of this note is to give an accessible proof of Moliens Theorem in Invariant Theory, in the language of today's Linear Algebra and Group Theory, in order to prevent this beautiful theorem from being forgotten.

  • 1595.
    Schellwat, Holger
    Örebro University, School of Science and Technology.
    Mutual benefits from combining ethnomusicology with ethnomathematics2016In: Music in an intercultural perspective / [ed] Antenor Ferreira Corrêa, Brasília: Strong Edições , 2016, p. 119-122Chapter in book (Other academic)
  • 1596.
    Schindler, Maike
    Örebro University, School of Science and Technology.
    Stärken beim Begründen: Natürlich differenzierend2016In: Mathematik lehren: Die Zeitschrift für den Unterricht in allen Schulstufen, ISSN 0175-2235, no 195, p. 20-24Article in journal (Other academic)
  • 1597.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Hussman, Stephan
    Technical university Dortmund, Dortmund, Germany.
    Ein Kontext für negative Zahlen ‒ auch für die Multiplikation: English: A context for negative numbers ‒ also for multiplication2014In: Mathematik lehren: Die Zeitschrift für den Unterricht in allen Schulstufen, ISSN 0175-2235, no 183, p. 28-32Article in journal (Other academic)
    Abstract [de]

    Der Beitrag stellt eine Konzept zur Einführung der negativen Zahlen sowie eine entsprechende Lernumgebung vor, das im Rahmen eines Unterrichtsprojekts erarbeitet wurde. Dazu wurde der tragfähige Kontext “Guthaben und Schulden" weiterentwickelt. Dieser kann beim Aufbau eines inhaltlichen Verstehens, das die Bedeutung von “Minus mal Minus" nicht auf eine Regel reduziert, hilfreich sein.          

  • 1598.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Hussmann, Stephan
    IEEM, Technische Universität Dortmund, Germany.
    About students’ individual concepts of negative integers ‒ in terms of the order relation2013In: Proceedings of the eighth congress of the European Society of Research in Mathematics Education: Cerme 8 / [ed] Behiye Ubuz, Çiğdem Haser, Maria Alessandra Mariotti, Ankara: Middle East Technical University , 2013, p. 373-382Conference paper (Refereed)
    Abstract [en]

    We investigated sixth graders’ individual concepts of negative integers right before they were introduced to the “world" of the negatives. In order to investigate students’ first ideas of negative numbers, we initially investigated their ideas concerning the order relation of integers. With a qualitative data analysis utilizing a theoretical lens concerning individual concept formation, we gained insight into the students’ individual procedures and conceptions as well as into how the procedures are linked to the students’ previous knowledge.

  • 1599.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Hußmann, Stephan
    IEEM, TU Dortmund University, Dortmund, Germany.
    Nilsson, Per
    Örebro University, School of Science and Technology.
    Bakker, Arthur
    Freudenthal Institute, Utrecht University, Utrecht, Netherlands.
    Sixth-grade students’ reasoning on the order relation of integers as influenced by prior experience: an inferentialist analysis2017In: Mathematics Education Research Journal, ISSN 1033-2170, E-ISSN 2211-050X, Vol. 29, no 4, p. 471-492Article in journal (Refereed)
    Abstract [en]

    Negative numbers are among the first formalizations students encounter in their mathematics learning that clearly differ from out-of-school experiences. What has not sufficiently been addressed in previous research is the question of how students draw on their prior experiences when reasoning on negative numbers and how they infer from these experiences. This article presents results from an empirical study investigating sixth-grade students’ reasoning and inferring from school-based and out-of-school experiences. In particular, it addresses the order relation, which deals with students’ very first encounters with negative numbers. Here, students can reason in different ways, depending on the experiences they draw on. We study how students reason before a lesson series and how their reasoning is influenced through this lesson series where the number line and the context debts-and-assets are predominant. For grasping the reasoning’s inferential and social nature and conducting in-depth analyses of two students’ reasoning, we use an epistemological framework that is based on the philosophical theory of inferentialism. The results illustrate how the students infer their reasoning from out-of-school and from school-based experiences both before and after the lesson series. They reveal interesting phenomena not previously analyzed in the research on the order relation for integers. 

  • 1600.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Joklitschke, Julia
    Ruhr-Universität Bochum, Bochum, Germany.
    Designing tasks for mathematically talented students2015In: CERME 9: Proceedings of the Ninth Congress of the European Society for Research in Mathematics Education / [ed] Konrad Krainer and Naďa Vondrová, Prague, Czech Republic: European Society for Research in Mathematics Education, 2015, p. 1066-1072Conference paper (Refereed)
    Abstract [en]

    For the Design Research project presented, a learning environment for mathematically talented and interested 7th-grade students was investigated. The results show that the subject matter of graph theory offers both opportunities and means for students to develop their abilities. The data analysis showed likewise how the tasks might be modified in order to impose on their potential and thereby foster students’ abilities of a formalized perception and pervasion of mathematical information and of generalization.

29303132333435 1551 - 1600 of 1915
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