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  • 1.
    Abong'o, Deborah
    et al.
    University of Nairobi, Kenya.
    Wandiga, Shem
    University of Nairobi. Kenya.
    Jumba, Isac
    University of Nairobi, Kenya.
    van den Brink, Paul
    Wageningen University, the Netherlands.
    Nazariwo, Betty
    Makerere University, Uganda.
    Madadi, Vincent
    University of Nairobi, Kenya.
    Wafula, Godfrey
    University of Nairobi, Kenya.
    Kylin, Henrik
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Nkedi-Kizza, Peter
    University of Florida, USA.
    Organochlorine pesticide residue levels in soil from the Nyando River catchment, Kenya2015In: Africa Journal of Physical Sciences, ISSN 2313-3317, Vol. 2, no 1, 18-32 p.Article in journal (Refereed)
    Abstract [en]

    Soil samples were collected from six locations representative of the Nyando River catchment area of the Lake Victoria over a period of two years. Sampling was done four times in the year in February, May, September and December 2005 and 2006 in farms where maize, tea, sugar cane, coffee, rice and vegetables have been grown over the years. This coincided with the effects of different seasons and farming activities on residue levels of the pesticides in use. The objective was to investigate levels and distribution of organochlorine pesticides that have either been banned or are restricted for use in Kenya. Organochlorine pesticides investigated were DDT, lindane, aldrin, dieldrin, heptachlor, endrin, endosulfan (both α- and β- isomers and endosulfan sulphate), the sum is called “total” or Σendosulfan and methoxychlor. Prior to the ban or restriction in use, these pesticides had found wide applications in public health for control of disease vectors and in agriculture for control of crop pests. The analysis revealed presence of all the targeted pesticides with the highest mean concentrations for methoxychlor 140 ± 1.5 μg/kg, Σendosulfan (30 ± 2.1 μg/kg), aldrin (18 ± 0.28 μg/kg), respectively. The results show the presence of these pesticides in soils in the basin and this could be impacting negatively on the ecosystem health of the area.

  • 2. Adamczyk, A.
    et al.
    Malinowski, M.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    High-resolution near-surface velocity model building using full-waveform inversion-a case study from southwest Sweden2014In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 197, no 3, 1693-1704 p.Article in journal (Refereed)
    Abstract [en]

    Full-waveform inversion (FWI) is an iterative optimization technique that provides high-resolution models of subsurface properties. Frequency-domain, acoustic FWI was applied to seismic data acquired over a known quick-clay landslide scar in southwest Sweden. We inverted data from three 2-D seismic profiles, 261-572 m long, two of them shot with small charges of dynamite and one with a sledgehammer. To our best knowledge this is the first published application of FWI to sledgehammer data. Both sources provided data suitable for waveform inversion, the sledgehammer data containing even wider frequency spectrum. Inversion was performed for frequency groups between 27.5 and 43.1 Hz for the explosive data and 27.5-51.0 Hz for the sledgehammer. The lowest inverted frequency was limited by the resonance frequency of the standard 28-Hz geophones used in the survey. High-velocity granitic bedrock in the area is undulated and very shallow (15-100 m below the surface), and exhibits a large P-wave velocity contrast to the overlying normally consolidated sediments. In order to mitigate the non-linearity of the inverse problem we designed a multiscale layer-stripping inversion strategy. Obtained P-wave velocity models allowed to delineate the top of the bedrock and revealed distinct layers within the overlying sediments of clays and coarse-grained materials. Models were verified in an extensive set of validating procedures and used for pre-stack depth migration, which confirmed their robustness.

  • 3.
    Ahmad, Nawaz
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. Policy Wing, Ministry of Petroleum and Natural Resources, Government of Pakistan, Pakistan.
    Wörman, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.
    Bottacin-Busolin, Andrea
    Sanchez-Vila, Xavier
    Reactive transport modeling of leaking CO2-saturated brine along a fractured pathway2015In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 42, 672-689 p.Article in journal (Refereed)
    Abstract [en]

    One concern regarding the underground storage of carbon dioxide (CO2) is its potential leakage from reservoirs. Over short period of time, the leakage risk is related mainly to CO2 as a separate supercritical fluid phase. However, over longer periods upon complete dissolution of injected CO2 in the fluid, the leakage risk is associated with dissolved phase CO2. Over the geological time scales, large-scale groundwater motion may cause displacement of brine containing dissolved CO2 along the conducting pathways. In this paper, we present a comprehensive modeling framework that describes the reactive transport of CO2-saturated brine along a fracture in the clay caprock based on the future, hypothetical leakage of the dissolved phase CO2. This study shows that the transport of leaked dissolved CO2 is significantly retarded by a combination of various physical and geochemical processes, such as mass exchange between conducting fracture and the neighboring rock matrix through molecular diffusion, sorption and calcite dissolution in the rock matrix. Mass stored in aqueous and adsorbed states in the rock matrix caused retention of dissolved CO2 along the leakage pathway. Calcite dissolution reaction in the rock matrix resulted in consumption of leaking dissolved CO2 and reduced its mass along the leakage pathway. Consumption and retention of dissolved CO2 along the leakage pathway have important implications for analyzing the potential reduction of CO2 fluxes from storage reservoirs over large periods and long travel pathways.

  • 4.
    Ahmadi, Omid
    et al.
    Department of Earth Sciences, Uppsala University.
    Juhlin, Christopher
    Department of Earth Sciences, Uppsala University, Uppsala universitet.
    Ask, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lund, Björn
    Department of Earth Sciences, Uppsala University.
    Revealing the deeper structure of the end-glacial Pärvie fault system in northern Sweden by seismic reflection profiling2015In: Solid Earth Discussions, ISSN 1869-9537, Vol. 6, no 2, 537-563 p.Article in journal (Refereed)
    Abstract [en]

    Fault scarps that extend up to 155 km and have offsets of tens of meters at the surface are present in the northern parts of Finland, Norway and Sweden. These fault scarps are inferred to have formed during earthquakes with magnitudes up to 8 at the time of the last deglaciation. The Pärvie fault system represents the largest earthquake so far documented in northern Scandinavia, both in terms of its length and its calculated magnitude. It is also the longest known glacially induced fault in the world. Present-day microearthquakes occur along the length of the fault scarp on the eastern side of the scarp, in general agreement with an east dipping main fault. In the central section of the fault, where there is a number of subsidiary faults east of the main fault, it has been unclear how the earthquakes relate to the faults mapped at the surface. A seismic profile across the Pärvie Fault system acquired in 2007, with a mechanical hammer as a source, showed a good correlation between the surface mapped faults and moderate to steeply dipping reflectors. The most pronounced reflector could be mapped to about 3 km depth. In an attempt to map the fault system to deeper levels, a new 22 km long 2-D seismic profile which followed the 2007 line was acquired in June 2014. For deeper penetration an explosive source with a maximum charge size of 8.34 kg in 20 m deep shot holes was used. Reflectors can now be traced to deeper levels with the main 65◦ east dipping fault interpreted as a weakly reflective structure. As in the previous profile, there is a pronounced strongly reflective 60◦ west dipping structure present to the east of the main fault that can now be mapped to about 8 km depth. Extrapolations of the main and subsidiary faults converge at a depth of about 11.5 km where current earthquake activity is concentrated, suggesting their intersection has created favorable conditions for seismic stress release. Based on the present and previous seismic reflection data, potential locations for future boreholes for drilling into the fault system are proposed.

  • 5.
    Ahmed, Engy
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holmström, Sara
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Soil Microorganisms and Mineral Weathering: Mechanics of Biotite Dissolution2012Conference paper (Other academic)
    Abstract [en]

    Soil microorganisms play an important role in the environment by contributing to leach and release of essential elements from soil minerals that are required not only for their own nutrition but also for plants growth. This study aims to compare between the mechanisms of different fungal and bacterial species isolated from podzol soil in biotite dissolution. Microplate devices with 6 wells were used for the biological weathering experiments. All of the sterilized microplate wells were filled with 4g/l of biotite followed by 12 ml of an iron free diluted mineral liquid medium. In these conditions, biotite particles are the only source of the essential elements for the microorganisms. To characterize the mechanisms of biotite dissolution, we monitored siderophores production, microbial biomass, pH, exchangeable cations concentration and SEM analysis for mineral surface. There was a significant difference between the behavior of the fungal and bacterial species in dissolution of biotite. This difference may be due to the variation of these microorganisms in their mechanics of interaction with mineral surface. It was observed also that these microorganisms directly and indirectly induce biotite dissolution. Defining soil as a system driven by biological mechanisms rather than chemical processes has major implications for our understanding of how the system functions and how it will respond to changing conditions.

  • 6.
    Ahmed, Engy
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holmström, Sara
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    THE MICROBE-MINERAL INTERACTIONS IN THE ACIDIC PODZOL SOIL2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, no 5, 564- p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Iron is a key component of the chemical architecture of the biosphere. Due to the low bioavailability of iron in the environment, microorganisms have developed specific uptake strategies, like siderophores, which are operationally defined as low-molecular-mass biogenic Fe(III)-binding compounds, that can increase iron’s bioavailability by promoting the dissolution of iron-bearing minerals. In the present study, we aimed to investigate the composition of hydroxamate siderophores in the soil horizons of the acidic podzol, and study how they are affected by the presence of specific mineral types and microbial communities.

     Three different minerals (apatite, biotite and oligioclase) were inserted in the soil horizons (O (organic), E (eluvial), B (upper illuvial), and C (mineral)). After two years, soil samples were collected from both the bulk soil (next to the minerals) and from the soil attached to the mineral surfaces. The concentration of ten different fungal tri-hydroxamates and five bacterial ones were determined by high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS). In addition, total microbial composition and diversity were studied.

    Our field experiment succeeded in describing the relationship between the presence of siderophores, soil horizon and mineral type, in addition to understanding the interaction between mineral type and soil microbial composition. A wide range of fungal and bacterial hydroxamates were detected throughout the soil profile. On the other hand, the presence of the minerals completely altered the diversity of siderophores. In addition, each mineral had a unique interaction with hydroxamates in the different soil horizons. There were also a good relationship between the microbial diversity and the siderophore distribution. 

  • 7.
    Ahmed, Engy
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holmström, Sara
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The Roles and Applications of Siderophores in Natural Environments2013Conference paper (Other academic)
    Abstract [en]

    Siderophores are organic compounds with low molecular mass that are produced by microorganisms growing under conditions of low iron. The primary function of these compounds is to chelate ferric iron from different terrestrial and aquatic habitats and thereby make it available for microbial cells.

    Siderophores have received much attention in recent years because of their potential roles and applications in various areas of environmental research. For instance, the production of siderophores can provide a quick identification of microbes to the species level that called “siderotyping”. On the other hand, siderophores could also function as biocontrol, biosensor, and bioremediation agents, in addition to their important role in mineral weathering and enhancing plant growth. In the present study, we aimed to investigate the composition of trihydroxamate siderophores in soil samples from different horizons (O (organic), E (eluvial), B (upper illuvial), and C (parent material)) of a podzol soil in Sweden, and study how they are affected by the presence of specific mineral types (apatite, biotite and oligioclase) that were inserted in the soil for two years in a field experiment.

    Our field experiment succeeded in describing the relationship between the presence of siderophores, soil horizons and mineral types. A wide range of fungal and bacterial hydroxamates were detected throughout the soil profile. On the other hand, the presence of the minerals completely altered the diversity of siderophores. In addition, each mineral had a unique interaction with hydroxamates in the different soil horizons. Our next step is to gain greater insight into the siderotyping to illustrate the relationship between the siderophore types that was found throughout the soil profile and on the different mineral surfaces and the microbial diversity by using metagenomic applications.

  • 8.
    Ahmed, Engy
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holmström, Sara
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Brüchert, Volker
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The Role of Microorganisms in the diversity and distribution of siderophores in Podzolic Forest Soil2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, no 2, 161--208(48) p.Article in journal (Other academic)
    Abstract [en]

    Iron is a key component of the chemical architecture of the biosphere. Due to the low bioavailability of iron in the environment, microorganisms have developed specific uptake strategies. The most important one is the production of siderophores, which are operationally defined as low-molecular-mass biogenic Fe (III)-binding compounds which may greatly increase bioavailability of Fe [1]. One of the primary biogeochemical functions of siderophores is therefore to increase Fe bioavailability by promoting the dissolution of iron-bearing minerals [2]. This study aims to understand the role of microorganisms in the chemical diversity and distribution of siderophores in podzol soil and how this diversity can contribute to the bioavailability of Fe in forest soil.Soil samples were collected from an experimental site in the area of Bispgården in central Sweden (63°07′N, 16°70′E) from the O (organic), E (eluvial), B1 (upper illuvial), and C (mineral) horizons. Concentration and chemical composition of dissolved and adsorbed siderophores in the soil samples were determined using colorimetric assays and high-performance liquid chromatography.The highest siderophore concentrations were found in the O layer and thereafter decreased by depth. Concentrations of dissolved hydroxamate, catecholate and carboxylate siderophores were up to 84, 17 and 0.2 nmol/ g soil, respectively. In contrast, concentrations of adsorbed hydroxamates, catecholates and carboxylates were only up to 1.8, 3 and 0.2 nmol/ g soil, respectively.Siderophore-producing microorganisms were isolated from the same soil samples. Viable fungi, bacteria and actinomycete counts ranged from 7 to 300, from 300 to 1800, and from 0 to 5 cfu/gm, respectively. The highest counts were found in the O and E layers. Only the E layer contained the three types of siderophore-producing microorganisms investigated in this study. Siderophores were extracted from culture filtrates of the isolated microorganisms when grown under iron-limited conditions. These extracts varied considerably in siderophore composition. Fungal isolates produced up to 183 μM of hydroxamates, especially those isolated from the O layer, whereas bacteria and actinomycete isolated from the O and E layers of the soil produced high amounts of carboxylate, catecholate and hydroxamate siderophores. Actinomycete produced up to 93 μM of hydroxamates and 47 μM of catecholates, while bacteria produced up to 34 μM of carboxylates and up to 14 μM of catecholates.The depth variability in concentration and chemical composition and the good correlation between abundance of siderophore-producing microorganisms and siderophore soil concentrations strongly suggest that these siderophore-producing microorganisms play an important role in the mobilization of iron in the podzol soil that may be important in iron availability to plants in forest environment.

    [1] Clay et al. (1981) Biochemistry 20, 2432-2436. [2] Duckworth et al. (2009) ChemGeol 260, 149-158.

  • 9.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Kolarctic ENBI EnviMIne2014Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The objectives of the project are to develop a methodology for environmentally safe mine closure under specific conditions in the Barents region by cross border cooperation, exchange experiences and scientific knowledge.

  • 10.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sulphide oxidation and geochemical processes in mine tailings2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The generation of acid mine drainage (AMD) from oxidation of sulphide- bearing waste is a world wide problem, due to low pH levels and the release of metals to recipients. It is therefore important to understand the fundamental geochemical processes occurring in mine waste. The geochemistry of the drainage water from the tailings at the abandoned Laver copper mine in Northern Sweden was studied in 2001 and compared with a previous study performed in 1993. All drainage water is collected in a brook, which means that Laver is a favourable site for mass balance studies. The results show a decrease in the amount of sulphide-associated elements such as S, Cu and Zn in the drainage water, and an increase of the pH level. It has been suggested that this is due to the decrease in the sulphide oxidation rate in the tailings. Modelling the oxidation front movement using the shrinking core model gives similar results. This indicates that the sulphur transported in the drainage water could relatively well reflect the oxidation rate in the tailings. Oxygen sampling was also performed in 2001- 2002 to evaluate whether the flux of oxygen into the tailings was restricted by a vegetation cover. The results show that vegetation does not limit oxygen diffusion into the tailings. There is an atmospheric concentration throughout a profile through oxidised grass covered tailings during the whole sampling period. Oxygen concentrations at depths where sulphide oxidation occurs show seasonal variations, probably due to varying water saturation. Cemented layers were sampled at two locations in the Laver impoundment tailings, where they had been formed in spite of the low sulphide content and lack of carbonates. The aim of the study was to determine the effects of cemented layer formation on metal mobility in the tailings. The cementing agents are jarosite and Fe-oxyhydroxides. Arsenic is strongly enriched and somewhat higher concentrations of Pb, V, Mo and Hg, compared to those in unoxidised tailings, occur in these layers. Sequential extraction shows that these metals are mostly adsorbed/co-precipitated with crystalline iron oxyhydroxides. The enriched metals will probably be remobilised if changes towards more reducing conditions occur, for instance as a result of remediation of the tailings impoundment. An attempt was made to use LA-ICP-SMS to quantify the role of pyrite surfaces as scavengers of metals in oxidising mine tailings. Pyrite grains were collected from a profile through the pyrite-rich tailings at the Kristineberg mine in Northern Sweden. At each spot hit by the laser, the surface layer was analysed in the first shot, and a second shot on the same spot indicated the chemical composition of the pyrite immediately below. The crater diameter for a laser shot is known, and by estimating the crater depth and total pyrite surface, the total enrichment on pyrite grains was calculated. Results are presented for As, Cd, Co, Cu, Ni and Zn. The results clearly show that there is an enrichment of As, Cd, Cu and Zn on the pyrite surfaces below the oxidation front in the tailings, but not of Co and Ni. Arsenic is also enriched on the pyrite grains that survived in the oxidised zone. However, only 1.4 to 3.1% of the Cd and Zn released by sulphide oxidation in the oxidised zone had been enriched on the pyrite surfaces in the unoxidised tailings, but for As and Cu the corresponding figures are about 64 and 43%, respectively. The results should not be taken too literally but allow the conclusion that scavenging to pyrite surfaces is an important process for retention of As and Cu below the oxidation front in pyrite-rich tailings. Although only pyrite grains that appeared to be fresh, without surface coatings, were used in this study, the possibility of a thin layer of Fe-hydroxides occurring must be considered. Both adsorption to the pyrite directly, or to Fe-oxyhydroxides, may explain the enrichment of As, Cd, Cu and Zn on the pyrite surfaces, and, in the case of Cu, also replacement of Fe (II) by Cu(II) in pyrite.

  • 11.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sulphide oxidation, oxygen diffusion and metal mobility in sulphide-bearing mine tailings in Northern Sweden2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Large quantities of sulphide-bearing mining wastes produced from ore processing are deposited throughout the world. Sulphide oxidation in the wastes may release acidic water with high concentrations of metals to the environment. Remediation strategies are usually site specific, since the physical and chemical properties of the wastes vary. Therefore, sulphide oxidation, oxygen diffusion and metal mobility in unoxidised and oxidised, remediated and unremediated wastes have been studied in the present work. The efficiency of different cover systems on unoxidised tailings from Kristineberg, were studied in pilot-scale test cells (5*5*3 m3)under field conditions. Clayey till, sewage sludge, apatite and Trisoplast were used as sealing layers and unspecified till as a protective cover. In one cell tailings were left uncovered. Unoxidised tailings in the test-cells in the initial stage after deposition showed relatively low sulphur release (600- 800 mg/l)in leachate waters, which probably was an effect of high moisture content in the tailings prior to deposition. Near-neutral pH found in the leachates was an effect of neutralisation by carbonate minerals present and lime (Ca(OH)2) added prior to deposition. Similar sulphur concentrations were found also in the uncovered tailings. The sulphide oxidation rate increased with time in the uncovered tailings, and decreased in the covered. The lowest oxygen concentrations were observed below the cover system with sewage sludge, which was the most effective barriar against oxygen in a short-term perspective. The oxygen fluxes through the clayey till and apatite layers were within the same magnitude and varied between 0.5 and 4 mole/year,m2. The Trisoplast layer seemed to have failed as a barrier against oxygen. Tailings studied at field scale at Laver and Kristineberg had oxidised for more than 50 years. The tailings at Kristineberg have high pyrite content (c.25% and 50%) and those at Laver have low grade of pyrrhotite (2-3%). The Laver tailings are unremediated, while at Kristineberg the tailings were remediated in 1996. The transport of metals in the drainage water at Laver decreased during a study period of 8 years. The transport of dissolved sulphur indicated a declining trend of sulphide oxidation rate in the tailings, which was confirmed by oxygen measurements in the tailings and weathering rate estimations. The decline was considered to be natural as a result of the increased distance that oxygen has to travel to reach unoxidised sulphide grains. The major part of the amounts of metals released by sulphide oxidation were secondarily retained in the tailings, and to a small extent in layers cemented by jarosite and Fe-(oxy)hydroxides. Sequential extraction of these layers showed that metals such as Cu and Pb were mostly associated with crystalline Fe-(oxy)hydroxides. Most important retention mechanism was, however, sorption onto minerals surfaces below the oxidation front. The studied Impoundment 1 at Kristineberg was remediated by two different methods; on one part a dry cover consisting of a sealing layer and a protective cover were applied, and the groundwater table was raised and a single dry cover applied on the other part. When the groundwater table was raised in oxidised tailings, secondarily retained metals such as Fe, Mg, Mn, S and Zn were remobilised resulting in increased concentrations in the groundwater. The concentrations declined with time, due to dilution by inflowing uncontaminated water. Decreased concentrations of Fe, Mg, Mn, S and Zn were observed also in the groundwater below the dry cover as the amount of percolating water decreased. The concentrations of trace elements such as Cd, Co, Cr, Cu, Ni and Pb were almost depleted in the groundwater, since these metals were retained within the tailings by mechanisms such as co-precipitation, precipitation and sorption. Analysis of pyrite grains by LA-ICP-SMS showed that pyrite surfaces were important for retention of As and Cu, in particular, but also for Cd and Zn. This study shows that the physico-chemical conditions expressed by pH and redox potential have a large impact on element mobility’s. For example, As was mobilised as a result of remediation, while the concentrations of most metals decreased in the drainage waters.

  • 12.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Andersson, Elin
    Vectura Consulting AB.
    Mueller, Seth
    Boliden Mineral AB.
    Neutralization/prevention of acid rock drainage using mixtures of alkaline by-products and sulfidic mine wastes2013In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 20, no 11, 7907-7916 p.Article in journal (Refereed)
    Abstract [en]

    Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system’s neutralization potential. Leachates from 1 m3 tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH < 2) with high concentrations of As (65 mg/L), Cu (6 mg/L), and Zn (150 mg/L) after 258 days. The leachate from water-saturated waste rock had lower concentrations of As and Cu (<2 μg/L), Pb and Zn (20 μg/L and 5 mg/L), respectively, and its pH was around 6. Crushed (<6 mm) waste rock mixed with different fractions (1–5 wt %) of green liquid dregs, fly ash, mesa lime, and argon oxygen decarburization (AOD) slag was leached on a small scale for 65 day, and showed near-neutral pH values, except for mixtures of waste rock with AOD slag and fly ash (5 % w/w) which were more basic (pH > 9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation

  • 13.
    Alakangas, Lena
    et al.
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Bark, Glenn
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Ericsson, Magnus
    Luleå tekniska universitet, Samhällsvetenskap.
    Martinsson, Olof
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Söderholm, Patrik
    Luleå tekniska universitet, Samhällsvetenskap.
    Wanhainen, Christina
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Weihed, Pär
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Öhlander, Björn
    Luleå tekniska universitet, Geovetenskap och miljöteknik.
    Norrbottens malm- och mineralresurs och dess potentiella betydelse för innovation, samhälle och miljö2014Report (Other academic)
    Abstract [sv]

    Gruvindustrins betydelse för samhällsutveckling och infrastruktur i Sverige och inte minst i Norrbottens län är mycket stor. De geologiska förutsättningarna att hitta nya brytvärda förekomster i Norrbotten är goda. Länet är tillsammans med Västerbotten en av Europas viktigaste regioner för utvinning av metaller. Det syns också i den nyligen framtagna regionala mineralstrategin för Norrbotten och Västerbotten. Visionen för den regionala mineralstrategin: ”Genom långsiktigt hållbart nyttjande av Norrbottens och Västerbottens läns mineralresurser har ytterligare tillväxt skapats i regionen och hela Sverige. Vi har utvecklat och stärkt vår ställning som ledande gruv- och mineralnation.”Eftersom framtidspotentialen för gruvnäringen är mycket god men okunnigheten hos både allmänhet och beslutsfattare om näringens betydelse för innovation och samhällsutveckling är stor, kopplat med en utbredd oro för miljöpåverkan, måste dessa viktiga framtidsfrågor belysas. Med finansiering från Länsstyrelsen i Norrbotten bedrevs därför under första hälften av 2014 en förstudie som syftade till att sammanfatta kunskapsläget om framtidens gruvindustri i Norrbotten. Resultaten av förstudien redovisas i den här rapporten. En viktig slutsats är att det under nästa strukturfondsperiod (med start 2015) behövs ett framtidsinriktat forskningsprogram för att belysa de möjligheter som finns. Denna förstudie utgör grund för en kommande ansökan till strukturfonderna. Kompetensen som finns vid Luleå tekniska universitet, Sveriges centrum för gruvrelaterad forskning och utbildning, bör användas för att studera troliga framtidsmöjligheter och hur de ska kunna användas för att få en så positiv utveckling som möjligt för länet. Projektet bör innehålla följande tre huvudinriktningar, som naturligtvis hör ihop:Vilka malm- och mineralresurser finns det potential för i Norrbotten, och vilka kommer sannolikt att exploateras i framtiden?Vad kommer den exploateringen att ha för betydelse för innovation och samhällsutveckling?Vad kommer den exploateringen att få för miljöeffekter och hur ska man göra för att minska miljöbelastningen?En annan slutsats är att nedlagda gruvområden inte måste ses som förstörd natur. Betydande mervärden som gruvturism skulle kunna skapas om vilja, kreativitet och beslutsamhet finns. Detta är ett givet utvecklingsområde där småföretag och entreprenörer kan göra stor insats om de politiska och myndighetsmässiga förutsättningarna finns. Dessa aspekter skulle också kunna belysas i det föreslagna forskningsprogrammet eller i ett eget projekt.

  • 14.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bark, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ericsson, Magnus
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Söderholm, Patrik
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Widerlund, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Norrbottens malm- och mineralresurs och dess potentiella betydelse för innovation, samhälle och miljö2014Report (Other academic)
    Abstract [sv]

    Gruvindustrins betydelse för samhällsutveckling och infrastruktur i Sverige och inte minst i Norrbottens län är mycket stor. De geologiska förutsättningarna att hitta nya brytvärda förekomster i Norrbotten är goda. Länet är tillsammans med Västerbotten en av Europas viktigaste regioner för utvinning av metaller. Det syns också i den nyligen framtagna regionala mineralstrategin för Norrbotten och Västerbotten. Visionen för den regionala mineralstrategin: ”Genom långsiktigt hållbart nyttjande av Norrbottens och Västerbottens läns mineralresurser har ytterligare tillväxt skapats i regionen och hela Sverige. Vi har utvecklat och stärkt vår ställning som ledande gruv- och mineralnation.”Eftersom framtidspotentialen för gruvnäringen är mycket god men okunnigheten hos både allmänhet och beslutsfattare om näringens betydelse för innovation och samhällsutveckling är stor, kopplat med en utbredd oro för miljöpåverkan, måste dessa viktiga framtidsfrågor belysas. Med finansiering från Länsstyrelsen i Norrbotten bedrevs därför under första hälften av 2014 en förstudie som syftade till att sammanfatta kunskapsläget om framtidens gruvindustri i Norrbotten. Resultaten av förstudien redovisas i den här rapporten. En viktig slutsats är att det under nästa strukturfondsperiod (med start 2015) behövs ett framtidsinriktat forskningsprogram för att belysa de möjligheter som finns. Denna förstudie utgör grund för en kommande ansökan till strukturfonderna. Kompetensen som finns vid Luleå tekniska universitet, Sveriges centrum för gruvrelaterad forskning och utbildning, bör användas för att studera troliga framtidsmöjligheter och hur de ska kunna användas för att få en så positiv utveckling som möjligt för länet. Projektet bör innehålla följande tre huvudinriktningar, som naturligtvis hör ihop:Vilka malm- och mineralresurser finns det potential för i Norrbotten, och vilka kommer sannolikt att exploateras i framtiden?Vad kommer den exploateringen att ha för betydelse för innovation och samhällsutveckling?Vad kommer den exploateringen att få för miljöeffekter och hur ska man göra för att minska miljöbelastningen?En annan slutsats är att nedlagda gruvområden inte måste ses som förstörd natur. Betydande mervärden som gruvturism skulle kunna skapas om vilja, kreativitet och beslutsamhet finns. Detta är ett givet utvecklingsområde där småföretag och entreprenörer kan göra stor insats om de politiska och myndighetsmässiga förutsättningarna finns. Dessa aspekter skulle också kunna belysas i det föreslagna forskningsprogrammet eller i ett eget projekt.

  • 15.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Dagli, Deniz
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Literature review on potential geochemical and geotechnical effects of adopting paste technology under cold climate conditions2013Report (Other academic)
    Abstract [en]

    The purpose of this literature review is to summarize the recent research regarding geochemical and geotechnical stability of paste tailings, identify knowledge gaps and future research needs. The present study has been conducted by the Division of Geosciences and Environmental Engineering together with the Division of Mining and Geotechnical Engineering at Luleå University of Technology on behalf of Boliden Mineral, LKAB and Outotec.A survey conducted by MEND (Mine Environment Neutral Drainage) in 2006 on the environmental effects related to the use of paste tailings summarizes that only a few studies had been performed about long-term effects on the surface and groundwater quality. Instead, the focus had been on the additives and the strength of the paste. It is still uncertain how the paste technology affects the long-term environmental stability from a geochemical point of view. Concerns regarding the stability of paste with high sulphide content are still relevant. Studies performed indicate that sulphide oxidation occurs within cemented paste as well as on the surface of non-cemented paste and cracks formed on the surfaces could induce oxidation. For cemented paste, metals released by sulphide oxidation might be sequestered due to high pH induced by the alkaline additives, but anion such as Se has been shown to be mobilized. The leachate has been shown to be near-neutral initially, but the neutrality decreases with time and probably metals sequestered in the matrix will also be released. Again, it should be noted that no long term study was performed on leaching of paste, cemented or uncemented. The longest leaching study was performed for one year. Arsenic has been proven to be retained in Ca-arsenates in cemented paste, but the long term stability of these precipitates is relatively unknown. Expanded secondary phases e.g. gypsum and ettringite have been observed to form when there is sulphate in the process or drainage of water. These phases could crack the paste, but, on the other hand, can also fill former cracks when deposited in layers. The effects of the formation of these phases are relatively uncertain in a long-term perspective. Presence of different elements such as ammonium, sulphates and metals in the water has been shown to negatively affect the curing process and therefore water is suggested to be treated before use. The presence of carbon dioxide during the paste formation could also affect the curing process, but could sequester metals in carbonate phases.Geotechnical and rheological properties of paste is well defined and documented. Several case studies have been found in literature providing valuable information about the details of the works being carried out. However, a difficulty has been noted during the investigation of the effects of cold climate conditions when current practice is applied in the colder parts of the world. It is not certain how some specific and vital parameters are going to be affected by cold temperatures. Parameters such as deposition slopes and deposition scheme, strength development of the paste are expected to be responsive to cold climate conditions. There are predictions about which properties are going to be affected in what way, but there is also a need to establish a scientific base for discussion. These have been highlighted as research needs and information gaps at the end of the report.

  • 16.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hamberg, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: ERA-MIN project "Tools for sustainable gold mining in EU"2014Other (Other (popular science, discussion, etc.))
    Abstract [en]

    This research identifies and evaluates environmental impacts and economical challenges of gold mining in Finland, Sweden, Portugal, Romania, Poland and Ireland. The focus of this project is in gold exploration, mineral processing, water treatment, waste management, environmental monitoring, risk assessment and socio-economic impacts of gold mining. Finasieras av Vinnova

  • 17.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lundberg, Angela
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nason, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Simulation of pyrite oxidation in fresh mine tailings under near-neutral conditions2012In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 14, no 8, 2245-2253 p.Article in journal (Refereed)
    Abstract [en]

    Sulphidic residual products from ore processing may produce acid rock drainage, when exposed to oxygen and water. Predictions of the magnitude of ARD and sulphide oxidation rates are of great importance in mine planning because they can be used to minimize or eliminate ARD and the associated economic and environmental costs. To address the lack of field data of sulphide oxidation rate in fresh sulphide-rich tailings under near-neutral conditions, determination and simulation of the rate was performed in pilot-scale at Kristineberg, northern Sweden. The quality of the drainage water was monitored, along with oxygen and carbon dioxide concentrations. The chemical composition of the solid tailings was also determined. The field data were compared to predictions from simulations of pyrite oxidation using a 1-D numerical model. The simulations' estimates of the amount of Fe and S released over a seven year period (52 kg and 178 kg, respectively) were in reasonably good agreement with those obtained by analysing the tailings (34 kg and 155 kg, respectively). The discrepancy is probably due to the formation of secondary precipitates such as iron hydroxides and gypsum; which are not accounted for in the model. The observed mass transport of Fe and S (0.05 and 1.0 kg per year, respectively) was much lower than expected on the basis of the simulations and the core data. Neutralization reactions involving carbonates in the tailings result in a near-neutral pH at all depths except at the oxidation front (pH < 5), indicating that the dissolution of carbonates was too slow for the acid to be neutralized, which instead neutralized deeper down in the tailings. This was also indicated by the reduced abundance of solid Ca at greater depths and the high levels of carbon dioxide both of which are consistent with the dissolution of carbonates. It could be concluded that the near-neutral pH in the tailings has no decreasing effect on the rate of sulphide oxidation, but does reduce the concentrations of dissolved elements in the drainage water due to the formation of secondary minerals. This means that sulphide oxidation rates may be underestimated if determined from drainage alone.

  • 18.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lundberg, Angela
    Öhlander, Björn
    Changes of groundwater quality in sulphide-bearing mine-tailings as a result of remediation at Kristineberg, northern Sweden2007In: Mining and the Environment International Conference: proceedings, Centre for Environmental Monitoring, Laurentian University , 2007Conference paper (Refereed)
    Abstract [en]

    At the Kristineberg mine in northern Sweden, sulphide-rich tailings left open for 50 years were remediated in 1996 by applying double dry cover on one part of an impoundment, and raised groundwater level combined with simple till cover on the other part. Groundwater pipes installed in the impoundment were sampled from 1998 during a period of 6 years. The results showed that the groundwater quality varied considerably in the impoundment, even under the same type of cover. Secondarily retained Fe, S, Mg, Mn and Z were remobilised when the groundwater was raised. In the part with raised groundwater level, the average concentration of Fe ranged from 2700 to 9000mg/l in 1998, and the range for S was 2200 to 7000mg/l. During 2003 the average concentrations had decreased and ranged between 150 and 900 mg/l for Fe and between 130 and 900 mg/l for S. The improvement of the water quality was caused by inflow of less contaminated groundwater and decreasing sulphide oxidation rate. The redox potential generally decreased and pH increased. The concentrations of Cd, Cu and Pb in groundwater decreased rather rapidly all over the impoundment after remediation. In areas with relatively high pH and low redox potential, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn were almost depleted.

  • 19.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lundberg, Angela
    Öhlander, Björn
    Pilot scale studies of different dry covers on sulphide-rich tailings in northern Sweden, oxygen diffusion2005In: Securing the future: international conference on mining and the environment, metals and energy recovery : proceedings, Stockholm: SweMin , 2005, 9-18 p.Conference paper (Other academic)
  • 20. Alakangas, Lena
    et al.
    Lundberg, Angela
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pilot-scale studies of different covers on unoxidised sulphide-rich tailings, northern Sweden: oxygen diffusion2010In: Mine Water and the Environment: proceedings of the 10th IMWA Congress 2008 : 2-5 June, 2008 - Karlovy Vary, Czech Republic / [ed] Nadia Rapantova; Zbyněk Hrkal, Ostrava: VSB - Technical University Ostrava, Faculty of Mining and Geology, Institute of Environmental Engineering , 2010, 347-350 p.Conference paper (Refereed)
    Abstract [en]

    The efficiency of five cover systems to decrease oxygen intrusion into sulphide-rich tailings was studied in pilot-scale test cells (5x5x3 m(3)). The covers consisted of clayey till, sewage sludge, fine-grained apatite concentrate or Trisoplast (a mixture of a polymer, bentonite and tailings sand) as sealing layers and unspecified till as protective cover. In one reference cell, tailings were uncovered. Oxygen concentrations below the entire covers were highest below the Trisoplast and apatite layers, and lowest below the sewage sludge layer. Effective diffusion coefficients (D-eff) and oxygen fluxes were estimated in the covers with non-oxygen-consuming sealing layers (clayey till and apatite). For the protective covers the Deff ranged between E-09 and E-07 m(2)/s, and for the sealing layers between E-10 and E-09 m(2)/s, and for the entire covers between E-10 and E-08 m(2)/s. Seasonal variations in D-eff were larger within the covers than between the different cover systems. Oxygen fluxes through the entire covers with clayey till and apatite ranged between 0.2 and 4 mole m(2)/year, which was a reduction of more than 99% compared to uncovered dry tailings.

  • 21.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Projekt: Användning av restprodukter för förhindrande sulfid oxidation i reaktivt gruvavfall- en förstudie2014Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    En inventering av lämpliga restmaterial för efterbehandling och behandling av gruvavfall har genomförts och resulterat i en rapport

  • 22.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Macsik, Josef
    Strategic services & Sustainable Development at Ecoloop.
    Nyström, Elsa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sandström, Nadia
    Luleå tekniska universitet.
    Andersson-Wikström, Alexandra
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hällström, Lina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kartläggning av restprodukter för efterbehandling och inhibering av gruvavfall: funktion tillgång och logistik2014Report (Other academic)
  • 23.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nyström, Elsa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Siren, Susanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Utilization of Industrial Residuals for Prevention of Sulphide Oxidation in Mine Wastes2014Other (Other (popular science, discussion, etc.))
  • 24.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nason, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Declining element concentrations in groundwater after remediation in sulphide-rich tailings at Kristineberg, northern Sweden2010In: Mine Water & Innovative Thinking / [ed] Ch. Wolkersdorfer; A. Freund, Cape Breton University Press , 2010, 323-327 p.Conference paper (Refereed)
  • 25.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Rasmussen, Torklid Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Development, Evaluation and Optimization of Measures to Reduce the Impact on the Environment from Mining Activities in Northern Regions2016Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Min-North is a transnational project financed by the Interreg Nord program and coordinated by LTU. The project is a cooperation between Geological survey of Finland, GTK, Oulo University (Finland), The Arctic University of Norway, UiT and several (>17) small and large enterprises and mining companies in the northern region with expertise within geology, waste management, geophysics and geochemistry. The overall goal is to reduce the environmental impacts of mining in the northern regions by developing, evaluating, optimizing environmental techniques. In Sweden, geophysical and geochemical techniques will be integrated to develop a 4D model for tracing pollution transport in the mine waste, mine areas and in(to) the surroundings.

  • 26.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sandström, Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rosenkranz, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hällström, Lina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Improve Resource Efficiency and Minimize Environmental Footprint2016Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The REMinE project is organized in five work packages that comprise: detailedcharacterization and risk assessment of the mine wastes selected (WP2), identification of new processing methods for mine waste (WP3), characterization and risk assessment of the remaining residuals (WP4), outlining business opportunities and environmental impact in a conceptual model for sustainable mining (WP5). The project comprises case studies of historical mine wastes from three different European countries, namely Portugal, Romania and Sweden. The interdisciplinary research collaboration in this project is innovative in the sense that separation of minerals and extraction of metals not only are basedon technical and economic gain but also considers the environmental perspective.

  • 27.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Formation and composition of cemented layers in low-sulphide mine tailings, Laver, northern Sweden2006In: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 50, no 6, 809-819 p.Article in journal (Refereed)
    Abstract [en]

    Cemented layers (hardpans) are common in carbonate or sulphide-rich mine tailings and where pyrrhotite is the predominating Fe-sulphide. Laver, northern Sweden, is an abandoned Cu-mine where the tailings have low pyrrhotite content, almost no pyrite and no carbonates. Two cemented layers at different locations in the Laver tailings impoundment were investigated, with the aim to determine their effects on metal mobility. The cementing agents were mainly jarosite and Fe-oxyhydroxides in the layer formed where the tailings have a barren surface, whereas only Fe-oxyhydroxides were identified below grass-covered tailings surface. Arsenic was enriched in both layers which also exhibit high concentrations of Mo, V, Hg and Pb compared to unoxidised tailings. Sequential extraction indicates that these metals and As were mainly retained with crystalline Fe-oxides, and therefore potentially will be remobilised if the oxic conditions become more reducing, for instance as a result of remediation of the tailings impoundment.

  • 28.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Pilot-scale studies of different covers on unoxidised sulphide-rich tailings in northern Sweden: the geochemistry of leachate waters2006In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 25, no 3, 171-183 p.Article in journal (Refereed)
    Abstract [en]

    Leachate water quality from covered and uncovered unoxidised sulphide-rich tailings in six pilot-scale (5x5x3 m3) test cells was monitored during 2004 and 2005. The covers consisted of a layer of clayey till, sewage sludge, apatite or Trisoplast (a commercial mixture of tailings, bentonite, and a polymer). All layers were protected by an unspecified till except in one reference cell, where the tailings were left open. All leachate waters showed near-neutral pH as a result of neutralization by calcite in the tailings and by Ca(OH)2 added prior to deposition. Average dissolved sulphur concentrations in the leachates were ≈ 600 mg L-1, except in the cell with sewage sludge (300 mg L-1). The source of sulphur was mainly pyrite oxidation, but residual sulphur probably remained from the enrichment process. The near-neutral pH favoured precipitation of metal-(oxy)hydroxides with subsequent removal of trace elements such as Cd, Cu and Pb (< 15 μg L-1) from the solutions. High concentrations of Co, Mn, Ni, and Zn were found in leachates from the apatite, Trisoplast, and uncovered tailings cells. High As concentrations were found in the leachates in the sewage sludge and clayey till cells. The lowest metal concentrations, redox potential, and highest pH were found in the sewage sludge cell. Decreased elemental metal concentrations during 2004 suggest improved performance over time.

  • 29.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    The effect of vegetation on mine tailings2003In: Program with Abstracts : Joint Annual Meeting, Geological Association of Canada; Mineralogical Association of Canada , 2003, Vol. 28Conference paper (Other academic)
    Abstract [en]

    One of the major aims with passive remediation of sulfide-bearing mine tailings is to minimize or exclude oxygen diffusion through the tailings and decrease the oxidation of sulfides. A vegetation cover could potentially decrease the oxygen flux by oxygen consumption during decay of organic matter. The abandoned Cu mine at Laver in northern Sweden has not been remediated except for establishment of vegetation, and this offers the opportunity to investigate the effect of a vegetation cover on tailings.Whole-year sampling of surface drainage water from the tailings impoundment was performed during 1993 and 2001. The release of metals was only 5-10 % of the estimated weathering rate in the tailings during 1993 because of secondary retainment within the tailings. Results from 2001 show decreasing concentrations of several elements and increasing pH, indicating decreasing oxidation rate.Pore-gas measurement in two vertical profiles shows that vegetation on the tailings has no effect as a barrier for oxygen diffusion in comparison with barren parts.Cemented layers, which have formed at various depths in the tailings, have decreased the flux of oxygen to deeper parts; this could be an explanation of the decreased oxidation rate. The different cemented layers in the tailings differ in chemical composition and physical characteristics. There are two major types, both of which both contain iron oxides and carbon. The origin of the carbon is possibly the vegetation cover. None of the cemented layers acts as a trap for heavy metals, but As is enriched.The effect of vegetation as a oxygen barrier is negligible, but vegetation could act as a source for organic matter that could increase aggregation of iron oxides and clay minerals, thereby enhancing the formation of cemented layers or increasing metal-organic complexes which decrease the mobility of metals.

  • 30.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Lundberg, Angela
    Changes of sulphide oxidation rates over time in mine tailings, Laver, Northern Sweden2009In: 8th International Conference on Acid Rock Drainage (ICARD) and Securing the Future: Mining, Metals & the Environment in a Sustainable Society 2009: Skelleftea, Sweden, 22 - 26 June 2009, Red Hook, NY: Curran Associates, Inc., 2009Conference paper (Refereed)
  • 31.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Lundberg, Angela
    Estimation of temporal changes in oxidation rates of sulphides in copper mine tailings at Laver, Northern Sweden2010In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 408, no 6, 1386-1302 p.Article in journal (Refereed)
    Abstract [en]

    Tailings containing pyrrhotite were deposited in an impoundment at a copper mine at Laver, Northern Sweden, which operated between 1936 and 1946. Since then the oxidation of sulphides has acidified recipient water courses and contaminated them with metals. Measurements from surface water sampled in 1993, 2001 and 2004-05 from a brook into which the tailing impoundment drains indicate that the amounts of sulphide-associated elements such as Cu, S and Zn released into the brook have decreased over time, while pH has increased. The mass transport of S in the brook during 1993 and 2001 corresponded well with the amount of S estimated to be released from the tailings by oxidation. Secondary precipitates such as covellite and gypsum, which can trap sulphur, were shown in earlier studies to be present in only low amounts. The annual release of elements from the tailings was estimated from the volume of tailings assumed to oxidise each year, which depends on movement of the oxidation front with time. The results indicate that the oxidation rate in the tailings has decreased over time, which may be due to the increased distance over which oxygen needs to diffuse to reach unoxidised sulphide grains, or their cores, in the tailings.

  • 32.
    Alam, M.S.
    et al.
    Memorial University of Newfoundland, Canada.
    Ahmed, Kazi Matin
    University of Dhaka, Bangladesh.
    Hasan, M.A.
    University of Dhaka, Bangladesh.
    Hossain, Muhammed
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Controls of sedimentary facies on arsenic mobilization in shallow aquifers of the Matlab North Upazila, southeastern Bangladesh2013Conference paper (Other academic)
    Abstract [en]

    Groundwater extracted from shallow (<100 m bgl) Holocene alluvial aquifers, is the primary source of drinking water in Matlab North Upazila, Southeast Bangladesh. The distribution of lithofacies and its relation to hydrochemistry in such heterogeneous deposits are of fundamental importance for the analysis of groundwater quality. Aquifer sediment samples were collected from 48 locations throughout the study area. Lithofacies distribution was characterized using grain size and sediment colors. Channel fills (sandy) and over bank (silt-clay) deposits the two main lithofacies groups, were identified. These sandy deposits represent an active meandering river or channel fills sediment sequence, which are usually capped by silts and clays of an over bank sediment sequence. All the collected sediments samples were generalized and subdivided based on four distinct color variations, such as Black, White, Off-white, and Red according to Munsell color chart and water-well drillers’ perception.

    Mineral compositions showed variability with the sediment color and grain size. Red and off-white sediments contain fewer amounts of metastable minerals (hornblende, actinolite, kyanite and pyroxenes etc.) than that of black sediments, whereas black sediments contain higher amount of biotite. The relatively high content of biotite and other dark colored ferromagnesian minerals are responsible for the black and grayish color of these sediments. Ferruginous coating on silicates, particularly on quartz grains, gives the red and off-white coloration. Based on the available information regarding sediment colors of aquifers in which tubewell screens were placed, 44 domestic hand pumped tubewells (HTWs) were selected for water sampling. The groundwater abstracted from black sediments of shallow aquifer showed higher concentrations in DOC (median: 5.81 mg/L), dissolved NH

    4+ (median: 3.47 mg/L), PO43- (median: 1.36 mg/L), Fe (median: 4.87 mg/L), As (median: 252.53 μg/L) and relatively low Mn (median: 0.54 mg/L) and SO42-(median: 0.59 mg/L) concentrations, whereas groundwater abstracted from off-white and red sediments of shallow aquifer showed lower concentrations in DOC (median: 1.95 and 1.71 mg/L, respectively), dissolved NH4+ (median: 0), PO43- (median: 0.14 and 0.04 mg/L, respectively), Fe (median: 2.25 and 0.63 mg/L, respectively), As (median: 17.36 and 15.05 μg/L, respectively) and relatively high Mn+2 (median: 1.12 and 1.15 mg/L, respectively) and SO42- (median: 0.79 and 0.78 mg/L, respectively) concentrations. The water samples collected from black sediments (median Eh: 211 mV) indicated most reducing environment, followed by white (median Eh: 227 mV), whereas off-white and red sediments (median Eh: 268 and 274 mV) signified less reducing environment. The study supports that the sediment colors in shallow aquifer can be a reliable indicator of high and low-As concentrations and can be a useful tool for local drillers to target arsenic safe aquifers.

  • 33.
    Al-Ani, Thair
    et al.
    Geological Survey of Finland, P.O.Box 96, 02151 Espoo.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Dawood, Anwaer
    Koya University.
    Siergieiev, Dmytro
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Trace elements in water and sediments of the Tigris river, Baghdad City, Iraq2014In: Journal of Environmental Hydrology, ISSN 1058-3912, E-ISSN 1996-7918, Vol. 22, 1-17 p., 6Article in journal (Refereed)
    Abstract [en]

    Industrial, agricultural and rural activities may result in pollution of watercourses with elevated trace metal concentrations and implications for water supply and ecosystem functioning. The concentration of the trace metals Fe, Mn, Zn, Co, Pb, Cu, and Cd in the water and clay fractions (<2μm) of the bank sediments of River Tigris in Baghdad city were determined. Dissolved trace metals concentrations were far below the upper permissible limits during 2012-2013. There was no consistent pattern between element concentrations and river discharge. Seasonal interrelations between water and sediments were most obvious for Fe that decreased in both environments with rising flows during autumn. Although independent of discharge, Mn in water and sediments often followed each other at all stations. Zinc, however, increased in the sediments and decreased in the water with discharge. The clay fractions were slightly to strongly enriched in trace metals with the gradient Co > Fe > Zn > Mn > Cu suggesting absorption of the metals on sediment substrate.

  • 34.
    Al-Ansari, Nadhir
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Aldardor, Wafa
    Al al-Bayt University.
    Siergieiev, Dmytro
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effect of treated wastewater irrigation on vegetables2013In: Journal of Environmental Hydrology, ISSN 1058-3912, E-ISSN 1996-7918, Vol. 21, 5Article in journal (Refereed)
    Abstract [en]

    Treated waste water is normally used for irrigation purposes in countries suffering from water shortages to narrow the gap between supply and demand. The concept behind this is to save water consumed for agricultural activities, which consumes most of the water, for municipal and industrial uses. The Alsukhna area in Jordan is used to grow vegetables which are irrigated by treated wastewater. Surface and groundwater samples from the Zarqa region were analyzed for their major cations, anions and heavy metals. The impact of the treated waste water on the chemical components of vegetables was studied using Zn, Mn, Fe, Pb and Ni in sweet and hot pepper, tomato, cauliflower, cabbage, squash, cucumber and eggplant which were compared with similar vegetables irrigated by natural unpolluted water from the Mafraq region. The four metals, namely Zn, Fe, Pb, and Ni, had concentrations higher than in the reference vegetables by 3423%, 155%, 397%, 2949% and 289%, 187%, 211%, 214% fortomato and cauliflower, respectively. Sweet pepper was mainly influenced by an increased content of Fe, which was almost 180% higher than that in sweet pepper from the Mafraq region. Hot pepper had highly elevated concentrations of Ni (6980%) and Zn (419%), while squash demonstrated high Zn (207%) and Pb (666%). When all the heavy metals are considered, the most affected vegetable is the hot pepper with an average percent of heavy metals accumulation of 1559% while the least effected is cabbage at 116%.

  • 35.
    Alasdair, Skelton
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Fredrik, Arghe
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Pitcairn, Iain
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Spatial coupling between spilitization and carbonation ofbasaltic sills in SW Scottish Highlands: evidence of amineralogical control of metamorphic fluid flow2011In: Geofluids, ISSN 1468-8115, E-ISSN 1468-8123, Vol. 11, no 3, 245-259 p.Article in journal (Refereed)
    Abstract [en]

    In a geochemical and petrological analysis of overprinting episodes of fluid–rock interaction in a well-studied metabasaltic sill in the SW Scottish Highlands, we show that syn-deformational access of metamorphic fluids and consequent fluid–rock interaction is at least in part controlled by preexisting mineralogical variations. Lithological and structural channelling of metamorphic fluids along the axis of the Ardrishaig Anticline, SW Scottish Highlands, caused carbonation of metabasaltic sills hosted by metasedimentary rocks of the Argyll Group in the Dalradian Supergroup. Analysis of chemical and mineralogical variability across a metabasaltic sill at Port Cill Maluaig shows that carbonation at greenschist to epidote–amphibolites facies conditions caused by infiltration of H2O-CO2 fluids was controlled by mineralogical variations, which were present before carbonation occurred. This variability probably reflects chemical and mineralogical changes imparted on the sill during premetamorphic spilitization. Calculation of precarbonation mineral modes reveals heterogeneous spatial distributions of epidote, amphibole, chlorite and epidote. This reflects both premetamorphic spilitization and prograde greenschist facies metamorphism prior to fluid flow. Spilitization caused albitization of primary plagioclase and spatially heterogeneous growth of epidote ± calcic amphibole ± chlorite ± quartz ± calcite. Greenschist facies metamorphism caused breakdown of primary pyroxene and continued, but spatially more homogeneous, growth of amphibole + chlorite ± quartz. These processes formed diffuse epidote-rich patches or semi-continuous layers. These might represent precursors of epidote segregations, which are better developed elsewhere in the SW Scottish Highlands. Chemical and field analyses of epidote reveal the evidence of local volume fluctuations associated with these concentrations of epidote. Transient permeability enhancement associated with these changes may have permitted higher fluid fluxes and therefore more extensive carbonation. This deflected metamorphic fluid such that its flow direction became more layer parallel, limiting propagation of the reaction front into the sill interior.

  • 36.
    Aldahan, Ala
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Scherer, Reed
    Sjunneskog, C
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics.
    Berggren, A-M
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Cosmogenic 10Be as an environmental tracer in subglacial Antarctic Lake2006In: SALE advanced Science and Technology Workshop, 24-26 April, Grenoble, France,, 2006, 2-3 p.Conference paper (Refereed)
  • 37.
    Alling, Vanja
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Porcelli, D.
    Mörth, Carl-Magnus
    Stockholm University, Faculty of Science, Department of Geological Sciences. Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Anderson, L. G.
    Sanchez-Garcia, L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Andersson, P. S.
    Humborg, Christoph
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Degradation of terrestrial organic carbon, primary production and out-gassing of CO2 in the Laptev and East Siberian Seas as inferred from delta C-13 values of DIC2012In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 0016-1258, Vol. 95, 143-159 p.Article in journal (Refereed)
    Abstract [en]

    The cycling of carbon on the Arctic shelves, including outgassing of CO2 to the atmosphere, is not clearly understood. Degradation of terrestrial organic carbon (OCter) has recently been shown to be pronounced over the East Siberian Arctic Shelf (ESAS), i.e. the Laptev and East Siberian Seas, producing dissolved inorganic carbon (DIC). To further explore the processes affecting DIC, an extensive suite of shelf water samples were collected during the summer of 2008, and assessed for the stable carbon isotopic composition of DIC (delta C-13(DIC)). The delta C-13(DIC) values varied between -7.2 parts per thousand to +1.6 parts per thousand and strongly deviated from the compositions expected from only mixing between river water and seawater. Model calculations suggest that the major processes causing these deviations from conservative mixing were addition of (DIC) by degradation of OCter, removal of DIC during primary production, and outgassing of CO2. All waters below the halocline in the ESAS had delta C-13(DIC) values that appear to reflect mixing of river water and seawater combined with additions of on average 70 +/- 20 mu M of DIC, originating from degradation of OCter in the coastal water column. This is of the same magnitude as the recently reported deficits of DOCter and POCter for the same waters. The surface waters in the East Siberian Sea had higher delta C-13(DIC) values and lower DIC concentrations than expected from conservative mixing, consistent with additions of DIC from degradation of OCter and outgassing of CO2. The outgassing of CO2 was equal to loss of 123 +/- 50 mu M DIC. Depleted delta C-13(POC) values of -29 parts per thousand to -32 parts per thousand in the mid to outer shelf regions are consistent with POC from phytoplankton production. The low delta C-13(POC) values are likely due to low delta C-13(DIC) of precursor DIC, which is due to degradation of OCter, rather than reflecting terrestrial input compositions. Overall, the delta C-13(DIC) values confirm recent suggestions of substantial degradation of OCter over the ESAS, and further show that a large part of the CO2 produced from degradation has been outgassed to the atmosphere.

  • 38.
    Alm, Elisabet
    Stockholm University.
    Sveconorwegian metallogenesis in Sweden2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two main ore types are found in the Sveconorwegian Orogen in southwestern Sweden (Southwest Scandinavian Domain). One of them comprises stratabound Cu mineralizations in the Dal group, located west of lake Vänern. The other comprises quartz veins with varying precious and base metal contents, distributed over 250 km between lake Mjøsa (southeastern Norway) and lake Vänern. In this thesis, both ore types are discussed, although the main emphasis is on Au-bearing quartz veins, particularly those in the Harnäs area near lake Vänern.

    The Dal group is a 2000 m thick sequence of clastic sediments and intercalated mafic volcanic rocks, metamorphosed under greenschist facies conditions. It records deposition mainly in a shallow marine basin, formed during a rift stage preceding the Sveconorwegian orogeny (c. 1.15-0.9 Ga). The volcanic rocks have been subject to various degrees of sodic and/or potassic alteration. Geochemical and Sm-Nd isotopic evidence indicate a continental setting of volcanism. Cu mineralizations (chalcopyrite and bornite) occur at two stratigraphic levels. An ore-genetic model involving synsedimentary (or syndiagenetic) deposition of sulphides from metal-bearing fluids is favoured.

    Among Au-bearing quartz veins in the Mjøsa-Vänern ore district, four paragenetic types have been distinguished: Cu-dominated veins with chalcopyrite and/or bornite; Pb-Cu-bearing veins with pyrite, galena and chalcopyrite; Zn-Pb-dominated veins with sphalerite, galena, pyrite and chalcopyrite; Mn-bearing vein(s) with galena, chalcopyrite and hausmannite. In addition, e.g. native gold, argyrodite, hessite, tellurobismuthite and altaite are recognized. The ore lead isotopic composition is complex and metals appear to be derived from a variety of source rocks.

    The orthogneisses, which constitute the host rocks to the Harnäs veins and the Brustad Au quartz veins (Eidsvoll, near lake Mjøsa), have been investigated with respect to geochemistry, U-Pb zircon age and feldspar lead isotopic composition. The obtained intrusion age of the Brustad augen gneiss is 1674 ± 10 Ma and this rock is considered to belong to the Transscandinavian Igneous Belt. The Harnäs gneiss yielded a protolith age of 1595 +24/-17 Ma and is considered to be a member of the Åmål granitoid suite. Both orthogneisses have undergone ductile deformation during the Sveconorwegian orogeny. A complete isotopic resetting of the feldspar lead through dynamic recrystallization in conjunction with this deformation, at c. 1.0 Ga, has been demonstrated.

    The steeply dipping Harnäs veins are hosted in a local left-lateral shear zone, which transects the fabric in the surrounding orthogneisses. The moderate wall rock alteration was mainly sericitic. Fluid inclusions show that the ore-bearing vein system at Harnäs developed essentially in three stages: a quartz stage, a pyrite-gold stage and finally a galena stage. The early ore fluid was CO2-bearing, of low salinity and with a temperature of c. 200 oC, while in the galena stage it was purely aqueous, with a slightly higher salinity and a slightly lower temperature. Oxygen and sulphur isotope results imply a predominantly metamorphic origin for the ore fluid and suggest that the fluid constituents were derived from the regional orthogneisses. Ore lead isotopic compositions indicate metal derivation from these orthogneisses shortly after the Sveconorwegian deformation and resetting of feldspar lead. Subordinate Au-anomalous quartz veins in the Harnäs area as well as the Brustad Au quartz veins show characteristics similar to the Harnäs veins. Despite recognized variations, e.g. in mineralogy, a common origin is envisaged for most veins in the Mjøsa-Vänern ore district. They are characterized as late Proterozoic orogenic type Au deposits, with modern analogues e.g. in the western Alps.

  • 39.
    Alsadi, Aram
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Sektionen för geokemi och hydrologi, Sveriges lantbruksuniversitet..
    Dynamiken hos organiskt kol i Mälarens avrinningsområde: flöden, drivande faktorer och modellering2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report, it has been investigated how the amount of organic carbon, TOC, varies in time and space in the basin of Mälaren, and what controls the TOC content in the lake. It is important to understand the dynamics of the TOC in the lake and its catchment because increased TOC in the water affects water quality and causes problems in the preparation of drinking water. Particularly, it can react with chlorine / UV- light and form carcinogenic substances. It can also increase the number of microbes in water distribution systems.

    In addition the work includes analysis of the relation between water chemistry variables, annual fluxes calculations (g/m2/year) of element flows to the lake and a modeling approach to a watershed.

    Annual fluxes calculations (g/m2/year) indicate that the largest supply of TOC to the lake comes from the northeast of the lake. Fyrisån accounts for the largest input of TOC to the lake. The high TOC-flux is due to a small proportion of open water in the catchment.

    Hydrological, chemical and meteorological data have been included in models to estimate the TOC content in the Mälaren. Input data processing, especially precipitation data, has been an important part of the work as it affects the whole model. Temperature, evapotranspiration and precipitation data were used in a hydrological model, HBV model, to simulate the flow from the catchment area. Then a process-based model, INCA-C, operated by the hydrological data and soil moisture, has been used to simulate the temporal patterns in TOC. The input variables to INCA-C- model, soil moisture and HER (Hydrological effective rainfall), have been simulated using the HBV- model.

    Those models were applied in Kolbäcksån, one of the lake's largest catchments. The modeling of Kolbäcksån resulted in a model that captured the dynamics of a few periods of the whole time series. The modeling of Kolbäcksån TOC-concentration resulted in a model that captured the dynamics between 1996 and 2009, but misses it between 2009 and June 2010. R2 and NS values obtained for the model were 0.086 and -0.059, respectively.

  • 40.
    Amakawa, Hiroshi
    et al.
    University of Tokyo.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Masuda, Akimasa
    University of Tokyo.
    Shimizu, Hiroshi
    University of Tokyo.
    Isotopic compositions of Ce, Nd and Sr in ferromanganese nodules from the Pacific and Atlantic Oceans, the Baltic and Barents Seas, and the Gulf of Bothnia1991In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 105, no 4, 554-565 p.Article in journal (Refereed)
    Abstract [en]

    Ferromanganese nodules from the Pacific and Atlantic Oceans, the Barents and Baltic Seas, and the Gulf of Bothnia were analyzed for the isotopic compositions of Ce, Nd and Sr and the abundances of REE, Ba and Sr. REE patterns of Barents, Baltic and Bothnian samples show no Ce anomaly, or even a negative one, in contrast to the positive anomaly observed for the Pacific and Atlantic samples. Moreover, the Baltic and Bothnian samples have distinctly low εNd values; average εNd values of the four regions are as follows: Pacific -5, Barents -10, Atlantic -11 and Baltic inclusive of Gulf of Bothnia -19. The characteristic low εNd values of the Baltic samples are indicative of the influence of Precambrian rocks from the Baltic shield. Of particular interest is the feature of the Ce isotopic composition that εCe values of the samples from the Pacific are negative and those from the other three regions positive. This novel finding might suggest a difference in sources of Ce between the Pacific and other regions. These results demonstrate that Ce isotopic ratios can be a useful tracer in marine geochemistry, in combination with isotopic compositions of Nd and Sr.

  • 41. Amakawa, Hiroshi
    et al.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Masuda, Akimasa
    Shimizu, Hiroshi
    Isotopic compositions of Ce, Nd and Sr in ferromanganese nodules from various oceanic regions1992In: Abstracts : 29th International Geological Congress, Kyoto, Japan, 24 August - 3 September 1992, 1992, 613- p.Conference paper (Other academic)
  • 42.
    Amofah, Lea Rastas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bhattacharya, Prosun
    Kungliga tekniska högskolan, KTH.
    Chemical extraction of As from a polluted soil2008In: Arsenic in the environment - Arsenic from nature to humans: Book of Abstracts, 2008, 205- p.Conference paper (Other academic)
  • 43.
    Amofah, Lea Rastas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bhattacharya, Prosun
    KTH-International Groundwater Arsenic Research Group, Department of Land and Water Resources Engineering, Royal Institute of Technology (KTH),.
    Extraction of arsenic from soils contaminated with wood preservation chemicals2010In: Soil & sediment contamination, ISSN 1532-0383, E-ISSN 1549-7887, Vol. 19, no 2, 142-159 p.Article in journal (Refereed)
    Abstract [en]

    Three soil samples contaminated by chromated zinc arsenate (CZA) or chromated copper arsenate (CCA) were investigated in a laboratory scale to study As mobilization and to identify a chemical agent that could be used in soil washing to extract arsenic. Besides high As extraction, the cost, occupational health issues and technical aspects were considered when selecting the chemical. Arsenic is strongly bound to CZA/CCA soils; only ∼50% of the tot-As was removed from water-washed soils. High Fe or Al mobilization is not necessarily indicative of high As removal from CZA/CCA soils. A high Cu/As-ratio and a large amount of soluble Ca in the soil hampered As extraction. The high ratio can be an indication of stable Cu-arsenates in soil. Calcium can react with the extraction agent or with As during extraction. Sodium hydroxide, dithionite with citrate (and oxalate) (dithionite solutions), and oxalate with citrate were the most efficient chemicals for removing As from the soils. The disadvantages of using these strong chemicals are: a high cost (oxalate with citrate); damage to equipment (dithionite solutions); an adverse impact on occupational health (dithionite solutions); or a deterioration in soil quality after extraction (NaOH and dithionite solutons). Phosphate, solutions based on NH2OH·HCl, or citrate were not efficient in mobilizing As from the soils.

  • 44.
    Amofah, Lea Rastas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bhattacharya, Prosun
    Department of Land and Water Resources Engineering, Royal Institute of Technology.
    The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil2011In: Journal of Soils and Sediments, ISSN 1439-0108, E-ISSN 1614-7480, Vol. 11, no 8, 1334-1344 p.Article in journal (Refereed)
    Abstract [en]

    Purpose: Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. Materials and methods: A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20°C, 30°C and 40°C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. Results and discussion: In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. Conclusions: For all extractants, mobilisation was most efficient at elevated temperature (40°C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed by OC solutions (affording significant reductions in As, Cr and Zn levels in the soil with short extraction times) at 40°C is recommended

  • 45. Anand, Rajagopal
    et al.
    Balakrishnan, Srinivasan
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Mezger, Klaus
    Neoarchean crustal growth by accretionary processes: Evidence from combined zircon–titanite U–Pb isotope studies on granitoid rocks around the Hutti greenstone belt, eastern Dharwar Craton, India2014In: Journal of Asian Earth Sciences, ISSN 1367-9120, Vol. 79, 72-85 p.Article in journal (Refereed)
    Abstract [en]

    The Neoarchean Hutti greenstone belt hosts mesothermal gold deposits and is surrounded by granitoid rocks on all sides. Combined U–Pb dating of zircon and titanite from the granitoid rocks constrains their emplacement history and subsequent geologic evolution. The Golapalli and Yelagatti granodiorites occurring to the north of the Hutti greenstone belt were emplaced at 2569 ± 17 Ma. The Yelagatti granodiorite yielded a younger titanite age of 2530 ± 6 Ma which indicates that it was affected by a post-crystallization thermal event that exceeded the titanite closure temperature. The western granodiorites from Kardikal have identical titanite and zircon ages of 2557 ± 6 Ma and 2559 ± 19 Ma, respectively. The eastern Kavital granodiorites yielded titanite ages of 2547 ± 6 Ma and 2544 ± 24 Ma which are identical to the published U–Pb zircon SHRIMP ages. These ages imply that the granitoid rocks surrounding the Hutti greenstone belt were formed as discrete batholiths within a short span of ca. 40 Ma between 2570 Ma and 2530 Ma ago. They were juxtaposed by horizontal tectonic forces against the supracrustal rocks that had formed in oceanic settings at the end of the Archean. The first phase of gold mineralization coincided with the last phase of granodiorite intrusion in the Hutti area. A metamorphic overprint occurred at ca. 2300 Ma ago that reset the Rb–Sr isotope system in biotites and possibly caused hydrothermal activity and enrichment of Au in the ore lodes. The eastern Dharwar Craton consists of quartz monzodiorite–granodiorite–granite suites of rocks that are younger than the greenstone belts that are older than ~2650 Ma reported from earlier studies. The granitoid magmatism took place between 2650 and 2510 Ma ago indicating accretionary growth of the eastern Dharwar Craton.

  • 46.
    Andersson, Annika
    Luleå tekniska universitet.
    Frazil ice at water intakes1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To provide a better understanding of how frazil ice deposits on trash racks at water intakes, the phenomenon was video recorded at two hydropower plants and in a refrigerated laboratory flume. Initial accretion of frazil ice around a single bar and the motion of particles in the vicinity of an obstacle was simulated through numerical modelling and studied using plastic particles in a laboratory flume. Ice initially accumulates on the upstream face of the bars, and it progresses then to the upstream sides of the bars. Tha frazil ice layer grows in all directions, and it finally bridges over the spaces between bars. The ice blockage starts at the upper part of the rack and progresses downward. The head losses across each intake, which are observed continuously at the plants, illustrate the degree and importance of ice growth. Observations from laboratory experiments with a single bar in a flume, showed that frazil ice particles deposited on all bar surfaces. Separate flume tests were run with plastic particles simulating ice particles. The frequency of collision of these particles with the front face of a rectangular bar varied with the particle density and the fluid velocity. In a test with particles of various sizes, the smaller particles were more likely to enter the side wake than larger ones. A mathematical model can be used to predict patterns of ice deposition that correspond to the observed results. Such a model must include a hydrodynamic part for viscous flows and a particle trajectory model. Some models neglect the term for force due to pressure gradient in their calculations of a particle trajectory because the particles had larger density than the surrounding fluid. Ice particles have almost the same density as the water and simulated results showed that this term, caused by the pressure gradient, is the dominant force that counter the momentum of the particles when they move in the region close to the obstacle. The simulated results were affected by the particle size distribution, therefore the size distribution of frazil ice particles in a river is a factor in further studies. In tests in which no particles were allowed to deposit on the front part of the bar, in a simulation of a heated bar, lesser amounts deposited on the other parts of the bar. Knowledge of the way frazil ice accumulates on water intakes and the initial ice accretion on individual trash racks should be valuable in future work for finding methods to reduce the ice blockage and in the verification of more detailed model studies.

  • 47. Andersson, Christian
    et al.
    Lundberg, Angela
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Distribution of snow cover accumulation: airborne ground penetrating radar surveys2002In: Proceedings of the XXII Nordic Hydrological Conference / [ed] Å. Killingtveit, 2002, 517-526 p.Conference paper (Refereed)
  • 48.
    Andersson, Karen
    et al.
    Department of Chemistry, Analytical and Marine Chemistry, Göteborg University.
    Dahlqvist, Ralf
    Department of Geology and Geochemistry, Stockholm University.
    Turner, David
    Department of Chemistry, Analytical and Marine Chemistry, Göteborg University.
    Stolpe, Björn
    Department of Chemistry, Analytical and Marine Chemistry, Göteborg University.
    Larsson, Tobias
    Department of Chemistry, Analytical and Marine Chemistry, Göteborg University.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Andersson, Per
    Laboratory for Isotope Geology. Swedish Museum of Natural History, Stockholm.
    Colloidal rare earth elements in a boreal river: changing sources and distributions during the spring flood2006In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 70, no 13, 3261-3274 p.Article in journal (Refereed)
    Abstract [en]

    Variations in the physico-chemical speciation of the rare earth elements (REE) have been investigated in a subarctic boreal river during an intense spring flood event using prefiltered (<100 μm) samples, cross-flow (ultra)filtration (CFF), flow field-flow fractionation (FlFFF), and diffusive gradients in thin films (DGT). This combination of techniques has provided new information regarding the release and transport of the REE in river water. The colloidal material can be described in terms of two fractions dominated by carbon and iron, respectively. These two fractions, termed colloidal carrier phases, showed significant temporal changes in concentration and size distribution. Before the spring flood, colloidal carbon concentrations were low, the colloids being dominated by relatively large iron colloids. Colloidal concentrations increased sharply during the spring flood, with smaller carbon colloids dominating. Following the spring flood, colloidal concentrations decreased again, smaller carbon colloids still dominating. The REE are transported mainly in the particulate and colloidal phases. Before the spring flood, the REE composition of all measured fractions was similar to local till. During the spring flood, the REE concentrations in the colloidal and particulate fractions increased. The increase was most marked for the lighter REE, which therefore showed a strong enrichment when normalized to local till. Following the spring flood, the REE concentrations decreased again and reverted to a distribution similar to local till. These changes in the concentration and distributions of carbon iron and REE are interpreted in terms of changing hydrological flow paths in soil and bedrock which occur during the spring flood.

  • 49.
    Andersson, Magnus
    et al.
    Department of Earth Sciences, Uppsala University.
    Malehmir, Alireza
    Department of Earth Sciences, Uppsala University.
    Troll, Valentin R.
    Department of Earth Sciences, Uppsala University.
    Dehghannejad, Mahdieh
    Department of Earth Sciences, Uppsala University.
    Juhlin, Christopher
    Department of Earth Sciences, Uppsala University.
    Ask, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Carbonatite ring-complexes explained by caldera-style volcanism2013In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 3, 1677Article in journal (Refereed)
    Abstract [en]

    Carbonatites are rare, carbonate-rich magmatic rocks that make up a minute portion of the crust only, yet they are of great relevance for our understanding of crustal and mantle processes. Although they occur in all continents and from Archaean to present, the deeper plumbing system of carbonatite ring-complexes is usually poorly constrained. Here, we show that carbonatite ring-complexes can be explained by caldera-style volcanism. Our geophysical investigation of the Alnö carbonatite ring-complex in central Sweden identifies a solidified saucer-shaped magma chamber at ∼3 km depth that links to surface exposures through a ring fault system. Caldera subsidence during final stages of activity caused carbonatite eruptions north of the main complex, providing the crucial element to connect plutonic and eruptive features of carbonatite magmatism. The way carbonatite magmas are stored, transported and erupt at the surface is thus comparable to known emplacement styles from silicic calderas.

  • 50.
    Andersson, Magnus
    et al.
    Department of Earth Sciences, Uppsala University.
    Malehmir, Alireza
    Department of Earth Sciences, Uppsala University.
    Dehghannejad, Mahdieh
    Uppsala University, Uppsala universitet, Department of Earth Sciences, Uppsala University.
    Troll, Valentin R.
    Department of Earth Sciences, Uppsala University.
    Ask, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Reflection seismic and potential-field investigations of the Alnö alkaline and Carbonatite igneous complex2014In: 74th EAGE conference and exhibition incorporating SPE EUROPEC 2012: Copenhagen, Denmark, 4 - 7 June 2012, Red Hook, NY: Curran Associates, Inc., 2014, 5393-5395 p.Conference paper (Refereed)
    Abstract [en]

    Alnö Island on the east coast of Sweden is well-known for its alkaline and carbonatite igneous rocks. Detailed surface geological mapping studies provide a good knowledge of the surface geology, from which geological structures and their depth extent have been inferred. The aim of this research is to constrain geological structures at depth and to improve our understanding of the intrusion mechanism(s) and the geometry of the Alnö complex as well as similar intrusions elsewhere. Three high-resolution reflection seismic profiles were acquired during 2011 across the complex. The seismic profiles suggest that the intrusion is highly reflective down to about 3 km at where the reflectivity terminates. Densely sampled surface gravity and magnetic data have also been acquired along the seismic profiles and in combination with petrophysical measurements and the seismic data will allow to construct a detailed 3D geological model of the Alnö complex.

1234567 1 - 50 of 1390
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