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  • 301. Conley, Daniel
    et al.
    Frings, Patrick J
    Swedish Museum of Natural History, Department of Geology.
    Fontorbe, Guillaume
    Clymans, Wim
    Stadmark, Johanna
    Hendry, Katherine
    Marron, Alan
    De La Rocha, Christina
    Biosilicification drives a decline of dissolved Si in the oceans through geologic time2017In: Frontiers in Marine Science, E-ISSN 2296-7745Article in journal (Refereed)
    Abstract [en]

    Biosilicification has driven variation in the global Si cycle over geologic time. The evolution of different eukaryotic lineages that convert dissolved Si (DSi) into mineralized structures (higher plants, siliceous sponges, radiolarians and diatoms) has driven a secular decrease in DSi in the global ocean leading to the low DSi concentrations seen today. Recent studies, however, have questioned the timing previously proposed for the DSi decreases and the concentration changes through deep time, which would have major implications for the cycling of carbon and other key nutrients in the ocean. Here, we combine relevant genomic data with geological data and present new hypotheses regarding the impact of the evolution of biosilicifying organisms on the DSi inventory of the oceans throughout deep time. Although there is no fossil evidence for true silica biomineralization until the late Precambrian, the timing of the evolution of silica transporter genes suggests that bacterial silicon-related metabolism has been present in the oceans since the Archean with eukaryotic silicon metabolism already occurring in the Neoproterozoic. We hypothesize that biological processes have influenced oceanic DSi concentrations since the beginning of oxygenic photosynthesis.

  • 302.
    Conrad, Sarah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Iron isotopes in aquatic systems2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The cycling of iron (Fe) is a key component for understanding water quality and biogeochemical processes. It serves as mediator during biotic and abiotic processes, as electron acceptor during the degradation of organic matter, as surface for trace element and organic matter adsorption, and is necessary for primary production processes. Since the beginning of Fe isotope studies, researchers focussed on the ratios in soils, rivers and oceans in various environments. The aim of this study was to characterize the Fe isotope ratios from the source (e.g. soils), along the river course, through the estuaries and into the adjacent sea within the boreal landscape. Therefore, seasonal sampling of water from Swedish headwater streams (2016/2017), rivers (2016), estuaries (2013/2014) and the Baltic Sea (2013/2014) were conducted, with the purpose to better understand the role and fate of riverine Fe export. Fe is transported in two main phases from the headwater streams into the oceans: organic Fe complexes and Fe(oxy)hydroxide. It has been proposed that these Fe phases varies in response to seasonal differences in hydrology.

                          This thesis includes the first Fe isotope dataset describing seasonal variations of headwater streams on a regional scale. In the headwater streams positive and negative Fe isotopes ratios can be used to distinguish between different Fe phases. Furthermore, Fe isotope ratios in headwater streams could verify regional drought periods and the subsequent rewetting of the subsurface soils.

    Within the rivers and estuaries, we found positive Fe isotopes in the dissolved phase (< 0.22µm) and negative Fe isotopes (> 0.22µm) in the particulate phase during high discharge. The correlation between different chemical parameters, Fe and DOC showed that the Fe isotope composition during spring flood is evolving in the upper soil layers of headwater streams. Therefore, the lighter Fe isotope signal is correlated to the organic-rich soil layers of the riparian zones in forested catchments. During baseflow, particulate Fe has a positive Fe isotope signal. This shows that the Fe has different origin throughout the season within one catchment.

    Salt-induced flocculation in the estuaries and under experimental conditions, is removing about 80 % of the dissolved and particulate Fe. Newly formed colloids and particles aggregate and sediment due to small changes in salinity. This major flocculation at low salinities might cause an underestimation of riverine Fe flux. Interestingly, salinity-induced aggregation experiments revealed that Fe(oxy)hydroxide, which dominated aggregates, displayed lower Fe isotope ratios than in the river samples Fe, while organic Fe complexes in the suspension had higher Fe isotope values. The seasonal variability in Fe isotope values could not be simply linked to Fe phases but was probably also influenced by variation in source areas of Fe and processes along the flow-path that alter both Fe phases and isotopic composition.

    Within the estuarine mixing zone, no Fe isotope fractionation was observed. The Fe isotope signal is constant over time and space, which excludes fractionation processes for example by oxidation. The Fe isotope signal within the Bothnian Bay was positive showing that different surface properties of Fe-OC and Fe(oxy)hydroxide aggregates lead to the flocculation of negative Fe aggregates.

  • 303.
    Conrad, Sarah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Origin of Iron Isotope Signatures in Boreal Estuaries2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The geochemistry of iron (Fe) during freshwater transport and estuarine mixing has been investigated. Espescially the changes in the Fe-isotope signature have been studied. The fate of Fe-isotopes during estuarine mixing has been poorly studied. Sampling was performed in Kalix River, Kalix and Råne estuary, and in the open Bothnian Bay, Northern Baltic Sea. Water samples were filtered with 0.22 μm membrane filters. Both particulate (> 0.22 μm) and colloidal fractions (< 0.22 μm) were analyzed. Iron particles and colloids, with a negative Fe-isotope signature, are formed during spring flood in forested catchments. These Fe complexes are associated with organic carbon (OC), and probably have a mixed oxidation state (Fe(II,III)-OC). Negative colloids are labile and flocculate and/or oxidize during riverine transport. Therefore, no negative colloids are detectable in the estuaries of the open Bothnian Bay. Within the estuaries two types of ˜56Fe signatures were measured: negative particles and positive colloids. The open Bothnian Bay shows a third distinct group of positive particles. This group mirrors the rapid removal of Fe colloids and particles at low salinities. Most of the Fe has been removed from surface water at salinities below 1.0 psu. Data in this study show that the Fe-isotopes can be used to trace the origin and cycling of iron particles and colloids in the boreal landscape.

  • 304.
    Conrad, Sarah
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Enrichment of heavy iron isotopes in suspended matter during estuarine mixing2015Conference paper (Other academic)
  • 305.
    Conrad, Sarah
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Fe-OC aggregates from headwaters to the estuary: The story of Fe-isotopes2016Conference paper (Refereed)
  • 306.
    Conrad, Sarah
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Iron isotope signatures in low salinity estuaries, northern Baltic Sea2014Conference paper (Refereed)
  • 307.
    Conrad, Sarah
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gelting, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nordblad, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Engström, Emma
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. ALS Laboratory Group, ALS Scandinavia AB, Luleå, Sweden .
    Rodushkin, Ilia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. ALS Laboratory Group, ALS Scandinavia AB, Luleå, Sweden .
    Andersson, Per S.
    Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Porcelli, Don
    Department of Earth Sciences, Oxford University, Oxford, UK.
    Gustafsson, Örjan
    Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden.
    Semiletov, Igor
    International Arctic Research Center (IARC), University of Alaska, Fairbanks, AK, USA. Pacific Oceanological Institute (POI), Far Eastern Branch of the Russian Academy of Sciences (FEBRAS), Vladivostok, Russia. Tomsk National Research Politechnical University, Arctic Seas Carbon International Research Laboratory, Tomsk, Russia.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Distribution of Fe isotopes in particles and colloids in the salinity gradient along the Lena River plume, Laptev Sea2019In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 16, no 6, p. 1305-1319Article in journal (Refereed)
    Abstract [en]

     Riverine Fe input is the primary Fe source for the ocean. This study is focused on the distribution of Fe along the Lena River freshwater plume in the Laptev Sea using samples from a 600 km long transect in front of the Lena River mouth. Separation of the particulate ( >  0.22 μm), colloidal (0.22 μm–1 kDa), and truly dissolved (<  1 kDa) fractions of Fe was carried out. The total Fe concentrations ranged from 0.2 to 57μM with Fe dominantly as particulate Fe. The loss of >  99% of particulate Fe and about 90% of the colloidal Fe was observed across the shelf, while the truly dissolved phase was almost constant across the Laptev Sea. Thus, the truly dissolved Fe could be an important source of bioavailable Fe for plankton in the central Arctic Ocean, together with the colloidal Fe. Fe-isotope analysis showed that the particulate phase and the sediment below the Lena River freshwater plume had negative δ56Fe values (relative to IRMM-14). The colloidal Fe phase showed negative δ56Fe values close to the river mouth (about -0.20 ‰) and positive δ56Fe values in the outermost stations (about +0.10 ‰). We suggest that the shelf zone acts as a sink for Fe particles and colloids with negative δ56Fe values, representing chemically reactive ferrihydrites. The positive δ56Fe values of the colloidal phase within the outer Lena River freshwater plume might represent Fe oxyhydroxides, which remain in the water column, and will be the predominant δ56Fe composition in the Arctic Ocean.

  • 308.
    Cooper, Mark
    et al.
    University of Manitoba, Winnipeg, Canada.
    Hawthorne, Frank
    University of Manitoba, Winnipeg, Canada.
    Langhof, Jörgen
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Holtstam, Dan
    Swedish Museum of Natural History, Department of Geology.
    Wiklundite, ideally Pb2[4](Mn2+,Zn)3(Fe3+,Mn2+)2(Mn2+,Mg)19(As3+O3)2[(Si,As5+)O4]6 (OH)18Cl6, a new mineral from Långban, Filipstad, Värmland, Sweden: Description and crystal structure2017In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 81, no 4, p. 841-855Article in journal (Refereed)
  • 309.
    Cordi, Ilja
    et al.
    Luleå tekniska universitet.
    Erixon, Peter
    Lundborg, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Förstudie om behov av miljökonsekvensbeskrivning i nya sammanhang inom vägsektorn1999Report (Other academic)
  • 310.
    Corrège, Olivier
    Luleå tekniska universitet.
    Evolution of the groundwater geochemistry in sulphide bearing tailings remediated by applying till cover, Kristineberg, Northern Sweden2001Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    At the Kristineberg mine in northern Sweden, sulphide-rich tailings were remediated in 1996 by applying till covers. The sulphides were isolated from the atmosphere to prevent oxidation. This was realised either by covering with unspecified till in combination with a raised groundwater level making the tailings water saturated, or by covering with compacted clayey till overlain by unspecified till (dry cover). During and after 1998, 14 groundwater pipes were installed in the tailings impoundment to study the effects of the remediation. Sampling has been performed on more than 32 occasions during more than three years, and the samples were analysed for major elements and metals, anions, pH, redox and conductivity. The results show that the groundwater characteristics vary considerably in the impoundment, even under the same type of cover. In the tailings with simple till cover and raised groundwater, in year 2001, pH ranges between 3.9 and 7, Fe-concentration between 30 and 19,000 mg/L, and Zn-concentration between 16 and 2,500,000 µg/L. The pH is generally increasing and redox is generally decreasing across the studied impoundment, where some areas showed quicker changes than others. The source reaction of the pollution seems to have stopped or slowed down. Natural buffering by chlorite dissolution occurred in the tailings. Metals such as Pb, Cu, and Cd decreased drastically after remediation, probably principally by adsorptions in connection with the raised pH, cutting the average concentrations across Impoundment 1 by up to 270 times for Cu. Before the remediation, metals released by sulphide oxidation were partly secondarily retained in the tailings below the oxidation front. Among them, Fe, S, Mg and Zn, have been remobilised by a first washout as a result of the raised groundwater level. A second washout by the clean groundwater from the western till slope, combined with the slowing down of the acid-producing reactions should lead to significant and general decreases in the observed concentrations in 2004-2005. However, iron precipitations occur in some places, creating a secondary acidification, and resulting in a secondary buffering by micas and release of adsorbed metals like Zn. The pathways and mixings of the groundwater in the impoundment which were first outlined by an hydrological study could be confirmed by the study of K, Ba and Sr. One of the main drawbacks of the remediation is an increased release of As, possibly in response to an increased pH, reaching up to 4350 mg/L As, as an average for year 2001 in one of the groundwater pipes.

  • 311. Cory, N.
    et al.
    Andrén, Cecilia M
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Bishop, K.
    Modelling inorganic Aluminium with WHAM in environmental monitoring2007In: APPLIED GEOCHEMISTRY, ISSN 0883-2927, Vol. 22, p. 1196-1201Article in journal (Refereed)
    Abstract [en]

    Due to the varying toxicity of different Al species, information about Al concentration and speciation is important when assessing water quality. Modelling Al speciation can support operational monitoring programmes where Al speciation is not measured directly. Modelling also makes it possible to retroactively speciate older samples where laboratory fractionation was not undertaken. Organic-rich waters are a particular challenge for both laboratory analysis and models. This paper presents the modelling of Al speciation in Swedish surface waters using the Windermere Humic Acid Model (WHAM). The model was calibrated with data from operational monitoring, the Swedish national survey of lakes and rivers, and covers a broad spectrum of physical and chemical conditions. Calibration was undertaken by varying the amount of DOC active in binding Al. A sensitivity analysis identified the minimum parameters required as model input variables primarily to be total Al, organic C, pH, F-, and secondly Fe, Ca and Mg. The observed and modelled Ali had no significant differences (Spearman rank, p < 0.01), however, lake samples modelled better than rivers. Samples were placed in the correct toxicological category in 89-95% of the cases. The importance of the size of the calibration data set was assessed, and reducing the calibration data set resulted in poorer correlations, but had little impact on the toxicological placement. Overall, the modelling gave satisfactory results from samples covering a broad spectrum of physical and chemical conditions. This indicates the potential value of WHAM as a tool in operational monitoring of surface waters.

  • 312. Dahl, Tais W.
    et al.
    Hammarlund, Emma
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Do large predatory fish track ocean oxygenation?2011In: Communicative & Integrative Biology, ISSN 1942-0889, E-ISSN 1942-0889, Vol. 4, no 1, p. 92-94Article in journal (Refereed)
    Abstract [en]

    The Devonian appearance of 1-10 meter long armored fish (placoderms) coincides with geochemical evidence recording a transition into fully oxygenated oceans.1 A comparison of extant fish shows that the large individuals are less tolerant to hypoxia than their smaller cousins. This leads us to hypothesize that Early Paleozoic O2 saturation levels were too low to support >1 meter size marine, predatory fish. According to a simple model, both oxygen uptake and oxygen demand scale positively with size, but the demand exceeds supply for the largest fish with an active, predatory life style. Therefore, the largest individuals may lead us to a lower limit on oceanic O2 concentrations. Our presented model suggests 2-10 meter long predators require >30-50% PAL while smaller fish would survive at <25% PAL. This is consistent with the hypothesis that low atmospheric oxygen pressure acted as an evolutionary barrier for fish to grow much above ~1 meter before the Devonian oxygenation.

  • 313. Dahl, Tais W.
    et al.
    Hammarlund, Emma U.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Anbar, Ariel D.
    Bond, David P. G.
    Gill, Benjamin C.
    Gordon, Gwyneth W.
    Knoll, Andrew H.
    Canfield, Donald E.
    Reply to Butterfield: The Devonian radiation of large predatory fish coincided with elevated athospheric oxygen levels2011In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 9, p. E29-Article in journal (Refereed)
    Abstract [en]

    We welcome this opportunity to clarify the conclusions and implications of our recent publication in PNAS. Butterfield (1) raises four issues regarding the oxygenation of the Paleozoic Earth's surface and its correlation to animal evolution. Our geochemical and paleontological data supported ocean oxygenation in the Silurian-Early Devonian (2), a critical transition in Earth history that influenced biogeochemical cycles and biological systems.

    First, Butterfield suggests that evidence of charcoal in late Silurian rocks is incompatible with our claim that the earlier Paleozoic atmosphere had oxygen levels below 50% PAL (present-day atmospheric level). This counterargument rests on the assumption that the “fire window” of 62–166% PAL oxygen is well defined, but this is not the case (3).

  • 314. Dahl, Tais W.
    et al.
    Hammarlund, Emma U.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Anbar, Ariel D.
    Bond, David P. G.
    Gill, Benjamin C.
    Gordon, Gwyneth W.
    Knoll, Andrew H.
    Nielsen, Arne T.
    Schovsbo, Niels H.
    Canfield, Donald E.
    Devonian rise in atmospheric oxygen correlated to the radiations of terrestrial plants and large predatory fish2010In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 107, no 42, p. 17911-17915Article in journal (Refereed)
    Abstract [en]

    The evolution of Earth's biota is intimately linked to the oxygenation of the oceans and atmosphere. We use the isotopic composition and concentration of molybdenum (Mo) in sedimentary rocks to explore this relationship. Our results indicate two episodes of global ocean oxygenation. The first coincides with the emergence of the Ediacaran fauna, including large, motile bilaterian animals, ca. 550-560 million year ago (Ma), reinforcing previous geochemical indications that Earth surface oxygenation facilitated this radiation. The second, perhaps larger, oxygenation took place around 400 Ma, well after the initial rise of animals and, therefore, suggesting that early metazoans evolved in a relatively low oxygen environment. This later oxygenation correlates with the diversification of vascular plants, which likely contributed to increased oxygenation through the enhanced burial of organic carbon in sediments. It also correlates with a pronounced radiation of large predatory fish, animals with high oxygen demand. We thereby couple the redox history of the atmosphere and oceans to major events in animal evolution.

  • 315. Dahlqvist, R.
    et al.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Behaviour of Ca during ultrafiltration of river water2002In: Vol. 66, no 15, Suppl. 1Article in journal (Refereed)
  • 316.
    Dahlqvist, Ralf
    et al.
    Department of Geology and Geochemistry, Stockholm University.
    Andersson, Karin
    Marine Chemistry, Department of Chemistry, Göteborg University.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Larsson, Tobias
    Marine Chemistry, Department of Chemistry, Göteborg University.
    Stolpe, Björn
    Marine Chemistry, Department of Chemistry, Göteborg University.
    Turner, David
    Marine Chemistry, Department of Chemistry, Göteborg University.
    Temporal variations of colloidal carrier phases and associated trace elements in a boreal river2007In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 71, no 22, p. 5339-5354Article in journal (Refereed)
    Abstract [en]

    Elemental size distributions, from truly dissolved through colloidal to particulate, have been studied in a subarctic boreal river. The measurements, carried out during 2002, ranged from winter to summer conditions, including an intense spring flood event. Results are reported for a total of 42 elements. Size distributions were characterised using a combination of cross-flow (ultra)filtration (CFF), flow field-flow fractionation (FlFFF), and diffusive gradients in thin-films (DGT). The three techniques showed similar trends, but quantitative comparisons reveal some important differences that warrant further investigation.

  • 317.
    Dahlqvist, Ralf
    et al.
    Laboratory for Isotope Geology. Swedish Museum of Natural History, Stockholm.
    Andersson, Per S.
    Luleå tekniska universitet.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The concentration and isotopic composition of diffusible Nd in fresh and marine waters2005In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 233, no 1-2, p. 9-16Article in journal (Refereed)
    Abstract [en]

    Variations in the Nd isotopic composition of ocean water through time, recorded in marine deposits, are suggested to document changes in erosional input and ocean circulation. Thus characterization of the dissolved Nd component in seawater is important. But few attempts have been made to directly measure truly dissolved Nd. Here we report Nd data, obtained using the technique of diffusive gradients in thin-films (DGT) designed to measure in situ, diffusible labile trace metals in aqueous solutions. The method samples free ions and possibly very small complexes. The concentration and isotopic composition of Nd in fresh, brackish and seawater have been determined with DGT, analyzed with thermal ionization mass-spectrometry, and compared with filtered and bulk water samples. Concentrations measured in water samples and with DGT show that the relative amount of diffusible Nd increases with salinity, from being about 10% in the fresh water to 42% in seawater. At each sampled site, the isotopic composition of Nd in the water shows a similar isotopic composition, within errors, with Nd sampled using the DGT method. These results indicate that there is a complete exchange between the particulate/colloidal fraction and the truly dissolved phase. Therefore our findings suggest that solute Nd reflects both the isotopic composition of the marine sediments and the bulk water.

  • 318. Dahlqvist, Ralf
    et al.
    Andersson, Per S.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The neodymium-isotopic composition in a boreal river: a reflection of selective weathering and colloidal transport1999In: Ninth annual V. M. Goldschmidt conference, 1999, p. 66-Conference paper (Other academic)
  • 319.
    Dahlqvist, Ralf
    et al.
    University of Oxford.
    Andersson, Per S.
    Swedish Museum of Natural History.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Porcelli, D.
    University of Oxford.
    Vertical REE profiles in water and DGT in the central Arctic Ocean2006In: Vol. 70, no 18S, p. A125-Article in journal (Other academic)
  • 320.
    Dahlqvist, Ralf
    et al.
    Department of Geology and Geochemistry, Stockholm University.
    Benedetti, Marc F.
    Laboratorie de Géochimie et Métallogénie, Universite Pierre et Marie Curie, Paris.
    Andersson, Karen
    Department of Chemistry, Analytical and Marine Chemistry, Göteborg University.
    Turner, David
    Department of Chemistry, Analytical and Marine Chemistry, Göteborg University.
    Larsson, Tobias
    Department of Chemistry, Analytical and Marine Chemistry, Göteborg University.
    Stolpe, Björn
    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.
    Association of calcium with colloidal particles and speciation of calcium in the Kalix and Amazon rivers2004In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 68, no 20, p. 4059-4075Article in journal (Refereed)
    Abstract [en]

    A considerable amount of colloidally bound Ca has been detected in water samples from Amazonian rivers and the Kalix River, a sub-arctic boreal river. Fractionation experiments using several analytical techniques and processing tools were conducted in order to elucidate the matter. Results show that on average 84% of the total Ca concentration is present as free Ca. Particulate, colloidal and complexed Ca constitute the remaining 16%, of which the colloidal fraction is significant. Ultrafiltration experiments show that the colloidal fraction in the sampled Amazonian rivers and the Kalix River range between 1% and 25%. In both the Amazonian and the Kalix rivers the technique of cross-flow ultrafiltration was used to isolate particles and colloids. The difference in concentration measured with ICP-AES and a Ca ion-selective electrode in identical samples was used to define the free Ca concentration and thus indirectly the magnitude of the particulate, colloidal and complexed fractions. Results from the Kalix and Amazonian rivers are in excellent agreement. Furthermore, the results show that the colloidal concentrations of Ca can be greatly overestimated (up to 227%) when conventional analysis and calculation of ultrafiltration data is used due to retention of free Ca ions during the ultrafiltration process. Calculation methods for colloidal matter are presented in this work, using complementary data from ISE analysis. In the Kalix River temporal changes in the fractionation of Ca were studied before, during and after a spring-flood event. Changes in the size distribution of colloidally associated Ca was studied using FlFFF (Flow Field-Flow Fractionation) coupled on-line to a HR ICP-MS. The FlFFF–HR ICP-MS fractograms clearly show the colloidal component of Ca, supporting the ultrafiltration findings. During winter conditions the size distribution of colloidally associated Ca has a concentration maximum at 5 to 10 nm in diameter, shifting to smaller sizes (<5 nm) during and after the spring flood. This shift in size distribution follows a change in the river during this period from ironoxyhydroxy colloids being the most important colloidal carrier phase to humic substances during and after the spring flood. WHAM and NICA-Donnan models were used to calculate the amount of colloidally bound Ca. The results similar for both models, show that on average 16% of the Ca may be associated to a colloidal phase, which is in broad agreement with the measurements.

  • 321.
    Dahlqvist, Ralf
    et al.
    Stockholm University.
    Zang, Hao
    Lancaster University.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Davidson, William
    Stockholm University.
    Performance of the diffusive gradients in thin films technique for measuring Ca and Mg in freshwater2002In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 460, no 2Article in journal (Refereed)
    Abstract [en]

    Measurements of the major cations Ca and Mg by the technique of diffusive gradients in thin films (DGTs) were systematically evaluated. The concentration in solution was calculated using Fick's first law of diffusion from the directly measured flux to the DGT device. A selective cation exchange resin (Bio-Rad Chelex®100), which has been used extensively with DGT for trace metals, such as Cd2+, Cu2+ and Ni2+, was used for this work. Elution of Ca and Mg from the resin with 1 M HNO3 was very reproducible. Measurements of Ca and Mg concentrations in synthetic solutions agreed well with the theoretical predictions. The negative response on uptake caused by lowered pH was investigated. Uptake was found to decline below pH 5. The capacity of the DGT device for Ca and Mg was also investigated to establish maximum deployment times for given concentrations. Experiments with filtered and modified lake water show that DGT can be used to measure Ca and Mg when trace metals are present in the solution. An in situ deployment of DGT combined with an ultrafiltration study suggest that the Mg concentration measured by DGT is similar to the concentration found in the fraction <1 kDa.

  • 322. Dalou, Celia
    et al.
    Füri, Evelyn
    Deligny, Cécile
    Piani, Laurette
    Caumon, Marie-Camille
    Laumonier, Mickael
    Boulliung, Julien
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Redox control on nitrogen isotope fractionation during planetary core formation2019In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 116, no 29, p. 14485-14494Article in journal (Refereed)
    Abstract [en]

    The present-day nitrogen isotopic compositions of Earth's surficial (N-15-enriched) and deep reservoirs (N-15-depleted) differ significantly. This distribution can neither be explained by modern mantle degassing nor recycling via subduction zones. As the effect of planetary differentiation on the behavior of N isotopes is poorly understood, we experimentally determined N-isotopic fractionations during metal-silicate partitioning (analogous to planetary core formation) over a large range of oxygen fugacities (Delta IW -3.1 < logfO(2) <Delta IW -0.5, where Delta IW is the logarithmic difference between experimental oxygen fugacity [fO(2)] conditions and that imposed by the coexistence of iron and wustite) at 1 GPa and 1,400 degrees C. We developed an in situ analytical method to measure the N-elemental and -isotopic compositions of experimental run products composed of Fe-C-N metal alloys and basaltic melts. Our results show substantial N-isotopic fractionations between metal alloys and silicate glasses, i.e., from -257 +/- 22% to -49 +/- 1% over 3 log units of fO(2). These large fractionations under reduced conditions can be explained by the large difference between N bonding in metal alloys (Fe-N) and in silicate glasses (as molecular N-2 and NH complexes). We show that the delta N-15 value of the silicate mantle could have increased by similar to 20 parts per thousand during core formation due to N segregation into the core.

  • 323.
    Das, Pallavi
    et al.
    Tezpur Univ, Dept Environm Sci, Napaam 784028, Assam, India.
    Sarma, Kali
    Tezpur Univ, Dept Environm Sci, Napaam 784028, Assam, India.
    Kumar Jha, Pawan
    Univ Allahabad, Ctr Environm Studies, Allahabad 211002, Uttar Pradesh, India.
    Ranjan, Rajnish
    North Eastern Elect Power Corp NEEPCO, Kameng Hydroelect Project, West Kameng, Arunachal Prade, India.
    Herbert, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Kumar, Manish
    Tezpur Univ, Dept Environm Sci, Napaam 784028, Assam, India.
    Understanding the Cyclicity of Chemical Weatheringand Associated CO2Consumption in the BrahmaputraRiver Basin (India): The Role of Major Rivers in ClimateChange Mitigation Perspective2016In: Aquatic geochemistry, ISSN 1380-6165, E-ISSN 1573-1421, Vol. 22, no 3, p. 225-251Article in journal (Refereed)
    Abstract [en]

    Weathering of rocks that regulate the water chemistry of the river has been used to evaluate the CO2 consumption rate which exerts a strong influence on the global climate. The foremost objective of the present research is to estimate the chemical weathering rate (CWR) of the continental water in the entire stretch of Brahmaputra River from upstream to downstream and their associated CO2 consumption rate. To establish the link between the rapid chemical weathering and thereby enhance CO2 drawdown from the atmosphere, the major ion composition of the Brahmaputra River that drains the Himalaya has been obtained. Major ion chemistry of the Brahmaputra River was resolved on samples collected from nine locations in pre-monsoon, monsoon and post-monsoon seasons for two cycles: cycle I (2011-2012) and cycle II (2013-2014). The physico-chemical parameters of water samples were analysed by employing standard methods. The Brahmaputra River was characterized by alkalinity, high concentration of Ca2+ and HCO3 (-) along with significant temporal variation in major ion composition. In general, it was found that water chemistry of the river was mainly controlled by rock weathering with minor contributions from atmospheric and anthropogenic sources. The effective CO2 pressure (log) for pre-monsoon, monsoon and post-monsoon has been estimated. The question of rates of chemical weathering (carbonate and silicate) was addressed by using TDS and run-off (mm year(-1)). It has been found that the extent of CWR is directly dependent on the CO2 consumption rate which may be further evaluated from the perspective of climate change mitigation The average annual CO2 consumption rate of the Brahmaputra River due to silicate and carbonate weathering was found to be 0.52 (x10(6) mol Km(-2) year(-1)) and 0.55 (x10(6) mol Km(-2) year(-1)) for cycle I and 0.49 (x10(6) mol Km(-2) year(-1)) and 0.52 (x10(6) mol Km(-2) year(-1)) for cycle II, respectively, which were significantly higher than that of other Himalayan rivers. Estimation of CWR of the Brahmaputra River indicates that carbonate weathering largely dominates the water chemistry of the Brahmaputra River.

  • 324. De Brabandere, L.
    et al.
    Bonaglia, Stefano
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Kononets, M.
    Viktorsson, Lena
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Stigebrandt, A.
    Thamdrup, B.
    Hall, P. O. J.
    Oxygenation of an anoxic fjord basin strongly stimulates benthic denitrification and DNRAManuscript (preprint) (Other academic)
  • 325.
    de Campos Pereira, Hugo
    Institutionen för mark och miljö, Sveriges Lantbruksuniversitet.
    Löslighet och transport av sällsynta jordartsmetaller i Källfallsfältets gruvsandsmagasin2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Solubility and transport of rare earth elements in the mine tailings of Källfallsfältet

    Hugo de Campos Pereira

    The mechanisms which govern the solubility of rare earth elements (REEs) in sulfide-containing tailings at the former mine site of Källfallsfältet (Västmanland, Sweden) were studied by the means of soil water and ground water sampling, leaching tests and geochemical modeling using Visual MINTEQ ver. 3.0.

    The results showed that weathering of sulfides is the primary process governing pH in the tailings, and thus also REE solubility. However, weathering of sulfides is no source for REE in itself since the elements are not bound in sulfides, which the oxidized availability test NT ENVIR 006 showed. Instead REE are released into solution by weathering of easily weathered silicates. Usually, metal bound in silicate form is not considered geochemically active.

    A kinetic (time dependent) factor, associated with the weathering of silicates, was found to affect pH and thus also metal solubility in leaching tests performed on the tailings. The standardized pH static leaching test (SIS-CEN/TS 14997) showed limitations in observing kinetic effects because of its relatively short equilibration time (48 h). Thus, in future studies with similar materials, leaching test kinetics should be taken into account when comparing leached concentrations with field measured concentrations. Acid titration and one step batch test (SIS-CEN ISO/TS 21268-2:2010) proved to be applicable and relatively well applicable to the tailings, respectively, in order to estimate soil solution concentrations.

    Speciation calculations using Visual MINTEQ ver. 3.0 showed that pH and DOC concentration are the most important factors which affect REE speciation in soil solution, ground water and surface water associated with the tailings. In acid sulfate rich solutions, low in DOC, speciation is dominated by sulfate complexes, mainly (REE)SO4+, followed by free dissolved ions as the second most common form. These results are in accordance with previous modeling studies of REE speciation in acid sulfate rich waters resulting from tailings. This, together with previous results showing that REE ecotoxicity seems to follow the free ion model, implies that the toxicity of the elements is expected to increase with decreasing pH value.

  • 326. Deegan, F.M.
    et al.
    Troll, V.R.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Jolis, E.M.
    Freda, C.
    Boron isotope fractionation in magma via crustal carbonate dissolution.2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 30774Article in journal (Refereed)
    Abstract [en]

    Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to −41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

  • 327. Deegan, F.M.
    et al.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Troll, V.R.
    Budd, D.A.
    Harris, C.
    Geiger, H.
    Hålenius, U.
    Swedish Museum of Natural History, Department of Geology.
    Pyroxene standards for SIMS oxygen isotope analysis and their application to Merapi volcano, Sunda arc, Indonesia2016In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 447, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Measurement of oxygen isotope ratios in common silicate minerals such as olivine, pyroxene, feldspar, garnet, and quartz is increasingly performed by Secondary Ion Mass Spectrometry (SIMS). However, certain mineral groups exhibit solid solution series, and the large compositional spectrum of these mineral phases will result in matrix effects during SIMS analysis. These matrix effects must be corrected through repeated analysis of compositionally similar standards to ensure accurate results. In order to widen the current applicability of SIMS to solid solution mineral groups in common igneous rocks, we performed SIMS homogeneity tests on new augite (NRM-AG-1) and enstatite (NRM-EN-2) reference materials sourced from Stromboli, Italy and Webster, North Carolina, respectively. Aliquots of the standard minerals were analysed by laser fluorination (LF) to establish their δ18O values. Repeated SIMS measurements were then performed on randomly oriented fragments of the same pyroxene crystals, which yielded a range in δ18O less than ± 0.42 and ± 0.58‰ (2σ) for NRM-AG-1 and NRM-EN-2, respectively. Homogeneity tests verified that NRM-AG-1 and NRM-EN-2 do not show any crystallographic orientation bias and that they are sufficiently homogeneous on the 20 μm scale to be used as routine mineral standards for SIMS δ18O analysis. We subsequently tested our new standard materials on recently erupted pyroxene crystals from Merapi volcano, Indonesia. The δ18O values for Merapi pyroxene obtained by SIMS (n = 204) agree within error with the LF-derived δ18O values for Merapi pyroxene but differ from bulk mineral and whole-rock data obtained by conventional fluorination. The bulk samples are offset to higher δ18O values as a result of incorporation of mineral and glass inclusions that in part reflects crustal contamination processes. The Merapi pyroxene SIMS data, in turn, display a frequency peak at 5.8‰, which allows us to estimate the δ18O value of the primary mafic magma at Merapi to ~ 6.1‰ when assuming closed system differentiation.

  • 328.
    Deegan, Frances M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Geiger, Harri
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Forensic Probe of Bali’s Great Volcano2019In: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 100, no 4, p. 26-30Article in journal (Refereed)
  • 329.
    Deegan, Frances M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Department of Geosciences, Swedish Museum of Natural History, SE-104 05, Stockholm, Sweden.
    Whitehouse, Martin
    Department of Geosciences, Swedish Museum of Natural History, SE-104 05, Stockholm, Sweden.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Budd, David A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Harris, Chris
    Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa.
    Geiger, Harri
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Hålenius, Ulf
    Department of Geosciences, Swedish Museum of Natural History, SE-104 05, Stockholm, Sweden.
    Pyroxene standards for SIMS oxygen isotope analysis and their application to Merapi volcano, Sunda arc, Indonesia2016In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 447, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Measurement of oxygen isotope ratios in common silicate minerals such as olivine, pyroxene, feldspar, garnet, and quartz is increasingly performed by Secondary Ion Mass Spectrometry (SIMS). However, certain mineral groups exhibit solid solution series, and the large compositional spectrum of these mineral phases will result in matrix effects during SIMS analysis. These matrix effects must be corrected through repeated analysis of compositionally similar standards to ensure accurate results. In order to widen the current applicability of SIMS to solid solution mineral groups in common igneous rocks, we performed SIMS homogeneity tests on new augite (NRM-AG-1) and enstatite (NRM-EN-2) reference materials sourced from Stromboli, Italy and Webster, North Carolina, respectively. Aliquots of the standard minerals were analysed by laser fluorination (LF) to establish their δ18O values. Repeated SIMS measurements were then performed on randomly oriented fragments of the same pyroxene crystals, which yielded a range in δ18O less than ± 0.42 and ± 0.58‰ (2σ) for NRM-AG-1 and NRM-EN-2, respectively. Homogeneity tests verified that NRM-AG-1 and NRM-EN-2 do not show any crystallographic orientation bias and that they are sufficiently homogeneous on the 20 μm scale to be used as routine mineral standards for SIMS δ18O analysis. We subsequently tested our new standard materials on recently erupted pyroxene crystals from Merapi volcano, Indonesia. The δ18O values for Merapi pyroxene obtained by SIMS (n = 204) agree within error with the LF-derived δ18O values for Merapi pyroxene but differ from bulk mineral and whole-rock data obtained by conventional fluorination. The bulk samples are offset to higher δ18O values as a result of incorporation of mineral and glass inclusions that in part reflects crustal contamination processes. The Merapi pyroxene SIMS data, in turn, display a frequency peak at 5.8‰, which allows us to estimate the δ18O value of the primary mafic magma at Merapi to ~ 6.1‰ when assuming closed system differentiation.

  • 330.
    Dekov, Vesselin M.
    et al.
    University of Sofia.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Billström, Kjell
    Swedish Museum of Natural History, Department of Geology.
    Kamenov, George D.
    University of Florida.
    Munnik, Frans
    Forschungszentrum Dresden-Rossendorf.
    Eriksson, Lars
    Stockholms universitet.
    Dyer, Alan
    University of Salford.
    Schmidt, Mark
    Leibniz-Institut für Meeresforschung, IFM-GEOMAR.
    Botz, Reiner
    Universität Kiel.
    Native Sn-Pb droplets in a zeolitic amygdale (Isle of Mull, Inner Hebrides)2009In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 73, p. 2907-2919Article in journal (Refereed)
  • 331.
    Dekov, Vesselin M.
    et al.
    IFREMER.
    Rouxel, Olivier
    Woods Hole Oceanographic Institution.
    Asael, Dan
    IFREMER.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Munnik, Frans
    Helmoholz-Zentrum Dresden-Rossendorf.
    Native Cu from the oceanic crust: Isotopic insights into native metal origin2013In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 359, p. 136-149Article in journal (Refereed)
  • 332.
    Deng, Juan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Liu, Jinshuo
    Li, Li
    Niu, Xin
    Zou, Bin
    Hierarchical Segmentation of Multitemporal RADARSAT-2 SAR Data Using Stationary Wavelet Transform and Algebraic Multigrid Method2014In: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 52, no 7, p. 4353-4363Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to develop a new effective method for hierarchical segmentation of multitemporal ultrafine-beam synthetic aperture radar (SAR) data in urban areas. Multitemporal RADARSAT-2 ultrafine-beam high-resolution horizontal transmit and horizontal receive-Synthetic Aperture Radar (HH-SAR) images acquired in the rural-urban fringe of the Greater Toronto Area during the summer of 2008 are selected for this research. Stationary wavelet transform (SWT) and algebraic multigrid (AMG) method are proposed for segmentation of SAR data. SWT is applied for decomposition of multitemporal SAR images in image preprocessing. The hierarchical and matrix-based AMG method is applied for segmentation. A pyramid of fine-to-coarse grids is constructed by iteration of selecting representative pixels and calculating the interpolation matrix between a fine-level grid and a coarse-level grid. When the pyramid is completed, segments are determined by a top-down scanning based on the interpolation matrices. The AMG techniques provide a complete hierarchical segmentation of SAR data. The experimental results show that our method produces higher accuracy than eCognition.

  • 333. Deng, Kai
    et al.
    Yang, Shouye
    Lei, Bi
    Chang, Yuan-Pin
    Su, Ni
    Frings, Patrick J
    Swedish Museum of Natural History, Department of Geology.
    Xie, Xiaolei
    Small dynamic mountainous rivers in Taiwan exhibit large sedimentary geochemical and provenance heterogeneity over multi-spatial scales2019In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 505, p. 96-109Article in journal (Refereed)
    Abstract [en]

    Taiwan rivers are characterized by extremely rapid mass wasting and sediment transfer due to active tectonics and frequent typhoons. Various methods have been applied to constrain processes affecting their sediment source-to-sink routing. In most cases, the sediment at the outlet is considered to be a representative average of the whole upstream basin due to the short sediment routes (<200 km). However, this assumption may be inappropriate because huge compositional heterogeneity can exist even within such small dynamic river systems. To reveal their intra-station and basin-wide geochemical heterogeneity, we collected sediment samples along the Zhuoshui and Liwu Rivers in Taiwan. Multiple samples deposited in different locations or with different grain-sizes were collected at each station, and the <63 μm fractions were measured for their elemental and Sr–Nd isotopic compositions. Elemental ratios and dimension-reducing technique were firstly applied to discriminate the sediment provenances. They show that the large elemental heterogeneity exists between samples at the same station and also between stations along each river, explainable by variable sediment mixing and local lithological heterogeneity. When combining our Sr–Nd isotopic data with literature data from Taiwan rivers, five discrete clusters of river sediments can be distinguished, reflecting the inter-catchment heterogeneity of sediment provenance in Taiwan Island. We also applied a Sr–Nd isotopic mixing model coupled with Monte-Carlo simulations to quantify the provenance heterogeneity in both rivers. The sediment contribution of the Western Foothills/Tailuko Belt to the Zhuoshui/Liwu downstream can vary by a factor of ∼2 between sediment samples that were considered as spatial or temporal replicates. Combined with field in-situ observations, we propose that fast-changing sediment transport modes cause the provenance heterogeneity in small dynamic mountainous rivers attacked by frequent heavy storms or typhoons. Sediments transported during different events and with different provenances can be preserved at each station, which leads to the intra-station and basin-wide geochemical heterogeneity. This study shows that “small” dynamic mountainous rivers can exhibit “large” geochemical and provenance heterogeneity over multi-spatial scales, and thus the common assumption that “let nature do the averaging” should be treated cautiously in this kind of river. Therefore, we propose several effective sediment sampling approaches on small mountainous rivers for reference. Future studies relying on detrital sediments, e.g. applying cosmogenic nuclides or Li isotopes, should also be aware of the heterogeneous nature in small mountainous rivers, because fast-changing provenances can simultaneously bias the weathering and erosion signals and lead to unrepresentative results.

  • 334.
    Destouni, Georgia
    et al.
    Stockholm University.
    Asokan, Shilpa
    Stockholm University.
    Augustsson, Anna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Balfors, Berit
    KTH Royal Institute of Technology.
    Bring, Arvid
    Stockholm University.
    Jaramillo, Fernando
    Stockholm University.
    Jarsjö, Jerker
    Stockholm University.
    Johansson, Emma
    Swedish Nuclear Fuel and Waste Management Co.
    Juston, John
    Stockholm University.
    Levi, Lea
    KTH Royal Institute of Technology.
    Olofsson, Bo
    KTH Royal Institute of Technology.
    Prieto, Carmen
    Stockholm University.
    Quin, Andrew
    Stockholm University.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Cvetkovic, Vladimir
    KTH Royal Institute of Technology.
    Biogeochemical Transformation Pathways through the Land-water Geosphere2014Conference paper (Refereed)
    Abstract [en]

    Water on land undergoes and participates in many biogeochemical exchanges and changes. A bits-and-pieces approach to these may miss essential aspects of change propagation and transformation by land-water through different segments of the Earth system. This paper proposes a conceptualization of the entire land-water geosphere as a scale-free catchment-wise organised system (Figure 1), emphasizing four key new system aspects compared to traditional hydrosphere/water cycle view: i) distinction of coastal divergent in addition to traditional convergent catchments; ii) physical and social-ecological system coupling through four main nodal zones/interfaces (surface, subsurface, coastal, observation); iii) flow-transport pathways as system coupling agents; iv) multiple interactions with the anthroposphere as integral system parts. Utilizing this conceptualization, we identify distinct patterns of direct anthropogenic change in large-scale water and waterborne nutrient fluxes, emerging across different parts of the world. In general, its embedment directly in the anthroposphere/technosphere makes land-water a key geosphere for understanding and monitoring human-driven biogeochemical changes. Further progress in system-level understanding of such changes requires studies of land-water as a continuous yet structured geosphere following the proposed spatiotemporal pathways of change propagation-transformation.

  • 335. Dickens, Gerald R.
    et al.
    Backman, Jan
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    A comment on "Pliocene climate change of the Southwest Pacific and the impact of ocean gateways" by C. Karas, D. Nurnberg, R. Tiedemann, D. Garbe Schonberg, EPSL 301, 117-124 (2011)2012In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 331, p. 364-365Article in journal (Other academic)
  • 336.
    D'Ippolito, Veronica
    et al.
    Sapienza Università di Roma.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Blue spinel crystals in the MgAl2O4-CoAl2O4 series: I. Flux growth and chemical characterisation2012In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 97, p. 1828-1833Article in journal (Refereed)
  • 337.
    D'Ippolito, Veronica
    et al.
    Sapienza Università di Roma.
    Andreozzi, Giovanni B.
    Sapienza Università di Roma.
    Bosi, Ferdinando
    Swedish Museum of Natural History, Department of Geology.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Mantovani, L.
    Università di Parma.
    Bersani, D.
    Università di Parma.
    Fregola, Rosa Anna
    Università di Bari.
    Crystallographic and spectroscopic characterisation of a natural Zn-rich spinel approaching the endmember gahnite (ZnAl2O4) composition2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, p. 2941-2953Article in journal (Refereed)
  • 338.
    D'Ippolito, Veronica
    et al.
    Sapienza University, Rome, Italy.
    Andreozzi, Giovanni
    Sapienza University, Rome, Italy.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Hametner, Kathrin
    ETH, Zürich, Switzerland.
    Günther, Detlef
    ETH, Zürich, Swizerland.
    Color mechanisms in spinel: cobalt and iron interplay for the blue color2015In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 42, no 6, p. 431-439Article in journal (Refereed)
    Abstract [en]

    Six natural, blue colored spinel crystals were studied chemically by electron microprobe and laser ablation inductively coupled plasma mass spectrometry (LAICP-MS) techniques and optically by UV–VIS–NIR–MIR spectroscopy in the range 30,000–2,000 cm1  to investigate the causes of their blue color hues. The positions of the absorption bands vary only marginally with the principal composition of the samples (gahnite vs. spinel s.s .). Although blue colors in spinels are frequently the result of various electronic processes in Fe cations, we demonstrate by comparison with synthetic Co-bearing samplesthat Co acts as an important chromophore also in natural spinels. Already at concentration levels of a few ppm (e.g.,>10 ppm), cobalt gives rise to absorption bands at ~18,000, 17,000 and 16,000 cm1  that result in distinct blue coloration. In spinels with insignificant Co contents, different shades of paler blue (from purplish to greenish blue) colors are caused by electronic transitions in TFe2+, MFe2+, MFe3and Fe2+–Fe3 cation pairs.

  • 339.
    Dold, Bernhard
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Acid rock drainage prediction: A critical review2016In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 172, p. 120-132Article in journal (Refereed)
    Abstract [en]

    Acid rock drainage (ARD) prediction is a very important issue in order to predict and prevent environmental pollution associated with mining activities. Nowadays, simple tests are widely applied and established in the mining and consulting business for ARD prediction. These tests have many known errors and problems, as that they do not account for the complexity of the mineral assemblage of an ore deposit, and therefore are not able to predict the geochemical behavior accurately. This critical review has the aim of first, highlighting the geochemical processes associated to the problems of ARD prediction. Secondly, the errors and limitations of the standard static and kinetic tests are highlighted. The currently applied calculation factor of 31.25 for sulfide acid potential calculation overestimates the carbonate neutralization potential by 100% in its geochemical assumptions. Thus, the calculation factor 62.5, based on the effective carbonate speciation at neutral pH, is recommended. Additionally, standard ABA procedure ignore the acid potential of Fe(III) hydroxides and/or sulfates and do not distinguish between different carbonate minerals. This can be critical, as for example siderite can be a net acid producing carbonate. Therefore, it is crucial to count on accurate quantitative mineral data in order to be able to accurately predict ARD formation and potential liberation of hazardous trace elements to the environment.

    In many modern mining operations, quantitative mineral data is nowadays produced in order to enhance the recovery of the extraction process by the incorporation of geometallurgical information (e.g. quantitative mineralogy, mineral liberation, textural information, grain size distribution). Thus, the use of this very same existing data for ARD prediction can increase importantly the precision of ARD prediction, often without additional costs and testing. The only requirement is the interdisciplinary collaboration between the different divisions and data exchange in a modern mining operation.

  • 340.
    Dold, Bernhard
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pooler, Robert
    SGS Minerals Chile, Geometallurgy Area, Puerto Madero 130, Pudahuel, Santiago.
    Optimization and quality control of automated quantitative mineralogy analysis for acid rock drainage prediction2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 1, article id 12Article in journal (Refereed)
    Abstract [en]

    Low ore-grade waste samples from the Codelco Andina mine that were analyzed in an environmental and mineralogical test program for acid rock drainage prediction, revealed inconsistencies between the quantitative mineralogical data (QEMSCAN®) and the results of geochemical characterizations by atomic absorption spectroscopy (AAS), LECO® furnace, and sequential extractions). For the QEMSCAN® results, biases were observed in the proportions of pyrite and calcium sulfate minerals detected. An analysis of the results indicated that the problems observed were likely associated with polished section preparation. Therefore, six different sample preparation protocols were tested and evaluated using three samples from the previous study. One of the methods, which involved particle size reduction and transverse section preparation, was identified as having the greatest potential for correcting the errors observed in the mineralogical analyses. Further, the biases in the quantities of calcium sulfate minerals detected were reduced through the use of ethylene glycol as a polishing lubricant. It is recommended that the sample preparation methodology described in this study be used in order to accurately quantify percentages of pyrite and calcium sulfate minerals in environmental mineralogical studies which use automated mineralogical analysis

  • 341.
    Drake, Alexandra
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Separating Acetate, Formate and MSA from natural samples using ion chromatography2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Anions from three short organic acids: acetate, formate and MSA are interesting to measure since they can be used for different environmental studies. The ion-chromatographer at the Department of Earth Sciences is currently not able to separate these three substances; therefore six new methods were developed in this project to solve this problem. Short organic test 5 ended up to be the best method, where acetate and formate were separated. The result was considered good, even if MSA were not separated.

    Method 5 was then tested on a couple of natural water, snow and ice samples. All these samples showed a larger amount of formate than of acetate, which in some cases was not even found. The results seemed plausible; not many of them were sticking out compared to others of the same phase. The shallowest sample from the Lomonosovfonna ice cap did however differ quite a lot in amount of formate compared with samples from other depths of this ice core; probably because of contamination which could have occurred at both the ice cap and in the lab during the handling of the samples.

    MSA can however also be measured if the amount of acetate and formate in the sample is known. This is done by adding known amounts of MSA to the same sample in subsequent runs to then be able to calculate the concentration of MSA in the sample. The problem with the use of this method is that the concentration of MSA needs to be high enough in contrast to acetate and formate in order to get reliable results, which was not the case in the samples measured in this project.

  • 342. Drake, H.
    et al.
    Tullborg, E.L.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Sandberg, B.
    Blomfeldt, T.
    Åström, M.E.
    Extreme fractionation and micro-scale variation of sulphur isotopes during bacterial sulphate reduction in deep groundwater systems.2015In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 161, p. 1-18Article in journal (Refereed)
    Abstract [en]

    This study conducted at the Äspö Hard Rock Laboratory, SE Sweden, determines the extent and mechanisms of sulphur-isotope fractionation in permanently reducing groundwater in fractured crystalline rock. Two boreholes >400 m below the ground surface were investigated. In the 17-year-old boreholes, the Al instrumentation pipes had corroded locally (i.e., Al-[oxy]hydroxides had formed) and minerals (i.e., pyrite, iron monosulphide, and calcite) had precipitated on various parts on the equipment. By chemically and isotopically comparing the precipitates on the withdrawn instrumentation and the borehole waters, we gained new insight into the dynamics of sulphate reduction, sulphide precipitation, and sulphur-isotope fractionation in deep-seated crystalline-rock settings. An astonishing feature of the pyrite is its huge variability in δ34S, which can exceed 100‰ in total (i.e., −47.2 to +53.3‰) and 60‰ over 50 μm of growth in a single crystal. The values at the low end of the range are up to 71‰ lower than measured in the dissolved sulphate in the water (20–30‰), which is larger than the maximum difference reported between sulphate and sulphide in pure-culture experiments (66‰) but within the range reported from natural sedimentary settings. Although single-step reduction seems likely, further studies are needed to rule out the effects of possible S disproportionation. The values at the high end of the range (i.e., high δ34Spy) are much higher than could be produced from the measured sulphate under any biogeochemical conditions. This strongly suggests the development of closed-system conditions near the growing pyrite, i.e., the rate of sulphate reduction exceeds the rate of sulphate diffusion in the local fluid near the pyrite, causing the local aqueous phase (and thus the forming pyrite) to become successively enriched in heavy S (34S). Consequently, the δ34S values of the forming pyrite become exceptionally high and strongly decoupled from the δ34S values of the sulphate in the bulk fluid. The Al-(oxy)hydroxide and calcite precipitates are explained by a combination of deposit and galvanic corrosion initiated by Al corrosion by H2S produced by sulphate-reducing microorganisms.

  • 343.
    Drake, Henrik
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Heim, Christine
    Göttingen university, Germany.
    Hogmalm, Johan
    Göteborgs universitet.
    Hansen, Bent
    Göttingen university, Germany.
    Fracture zone-scale variation of trace elements and stable isotopes in calcite in a crystalline rock setting2014In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 40, p. 11-24Article in journal (Refereed)
    Abstract [en]

    With an aim to increase the understanding about the isotopic and chemical heterogeneity of calcites in water-conducting fracture zones with different crystalline wall rock compositions at different depths, we present trace element chemistry, isotopic composition (δ18O, δ13C, 87Sr/86Sr) and biomarkers of euhedral low-temperature fracture-coating calcite. Paleohydrogeological fluctuations and wall rock influence on the hydrochemistry in the deep groundwater are explored. Samples are from several fracture zone sub-fractures (at −360 to −740 m), retrieved during an extensive core drilling campaign in Sweden.

    Calcite generally showed fracture zone specific values of δ13C, δ18O and 87Sr/86Sr, which indicates precipitation from relatively homogeneous fluid (similar to the modern groundwater at the site) at the same event in each fracture zone. δ18O and δ13C in the different fracture zones were consistent with precipitation from waters of different salinity and decreasing organic input with depth, respectively. The latter is also supported by biomarkers showing clear indications of SRB-related organic compounds (e.g. iso- and anteiso-C17:0-branched fatty acids), except in the deepest zone. In contrast to the isotopes, variation in trace elements within the fracture zones was generally up to several orders of magnitude. Manganese and REE, as oppose to the other metals, were higher in the shallow fracture zones (112–1130 and 44–97 ppm, respectively) than in the deeper (28–272 and 5–11 ppm, respectively), in agreement with the groundwater composition. Although the rock types varied between and within the different fracture zones, this had insignificant influence on the trace element chemistry of the calcites. Co-variation was generally relatively large for many trace elements, with isometric logratio correlation generally better than 0.75, which indicates that their variation in the calcites is due to variation of Ca in the fracture water, but other local factors, especially uptake in co-precipitating minerals (clay minerals, barite, pyrite and zeolites), but also microbial activity and metal speciation may have influenced the metal incorporation into calcite. These detailed studies of fracture calcite are of importance for the understanding of variation in fluid chemistry and trace metal uptake in fracture zones, adding together with hydrochemical studies detailed information optimal for site characterisation.

  • 344. Drake, Henrik
    et al.
    Ivarsson, Magnus
    Tillberg, Mikael
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Ancient Microbial Activity in Deep Hydraulically Conductive Fracture Zones within the Forsmark Target Area for Geological Nuclear Waste Disposal, Sweden2018In: Geosciences, Vol. 8, no 211Article in journal (Refereed)
    Abstract [en]

    Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of δ13Ccalcite (−36.2 to +20.2‰ V-PDB) and δ34Spyrite (−11.7 to +37.8‰ V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of δ18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded.

  • 345.
    Drake, Henrik
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Ivarsson, Magnus
    University of Southern Denmark, Denmark.
    Tillberg, Mikael
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Whitehouse, Martin
    Swedish Museum of Natural History.
    Kooijman, Ellen
    Swedish Museum of Natural History.
    Ancient Microbial Activity in Deep Hydraulically Conductive Fracture Zones within the Forsmark Target Area for Geological Nuclear Waste Disposal, Sweden2018In: Geosciences, E-ISSN 2076-3263, Vol. 8, no 6, article id 211Article in journal (Refereed)
    Abstract [en]

    Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of δ13Ccalcite (−36.2 to +20.2‰ V-PDB) and δ34Spyrite (−11.7 to +37.8‰ V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of δ18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded

  • 346.
    Drake, Henrik
    et al.
    Department of Biology and Environmental Science, Linnaeus University, 39231 Kalmar, Sweden.
    Mathurin, Frédéric A.
    Department of Biology and Environmental Science, Linnaeus University, 39231 Kalmar, Sweden.
    Zack, Thomas
    Department of Earth Science, University of Gothenburg, Gothenburg, Sweden.
    Schäfer, Thorsten
    Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, 76021 Karlsruhe, Germany.
    Nick MW, Roberts
    NERC Isotope Geosciences Laboratory, British Geological Survey, Nottingham NG12 5GG, U.K..
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Broman, Curt
    Department of Geological Sciences, Stockholm University, Stockholm 106 91, Sweden.
    Mats E., Åström
    Department of Biology and Environmental Science, Linnaeus University, 39231 Kalmar, Sweden.
    Incorporation of Metals into Calcite in a Deep Anoxic Granite Aquifer2018In: Environmental Science and Technology, ISSN 1086-931X, E-ISSN 1520-6912, Vol. 52, no 2, p. 293-502Article in journal (Refereed)
    Abstract [en]

    Understanding metal scavenging by calcite in deep aquifers in granite is of importance for deciphering and modeling hydrochemical fluctuations and water–rock interaction in the upper crust and for retention mechanisms associated with underground repositories for toxic wastes. Metal scavenging into calcite has generally been established in the laboratory or in natural environments that cannot be unreservedly applied to conditions in deep crystalline rocks, an environment of broad interest for nuclear waste repositories. Here, we report a microanalytical study of calcite precipitated over a period of 17 years from anoxic, low-temperature (14 °C), neutral (pH: 7.4–7.7), and brackish (Cl: 1700–7100 mg/L) groundwater flowing in fractures at >400 m depth in granite rock. This enabled assessment of the trace metal uptake by calcite under these deep-seated conditions. Aquatic speciation modeling was carried out to assess influence of metal complexation on the partitioning into calcite. The resulting environment-specific partition coefficients were for several divalent ions in line with values obtained in controlled laboratory experiments, whereas for several other ions they differed substantially. High absolute uptake of rare earth elements and U(IV) suggests that coprecipitation into calcite can be an important sink for these metals and analogousactinides in the vicinity of geological repositories.

  • 347.
    Drake, Henrik
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Tullborg, Eva-Lena
    Terralogica AB, Gråbo, Sweden.
    Hogmalm, Johan
    Göteborgs universitet.
    Åström, Mats E.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Trace metal distribution and isotope variations in low-temperature calcite and groundwaters in granitoid fractures down to 1 km depth2012In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 84, p. 217-238Article in journal (Refereed)
    Abstract [en]

    Studies of low-temperature fracture calcite in Proterozoic or Archaean crystalline rocks are very limited, mainly becausethis calcite usually is, first, not very abundant and second, very fine-grained or forms rims on older (and much more abundant)hydrothermal calcite and is thus difficult to distinguish. Knowledge of chemical characteristics and the correlation withgroundwater chemistry is thus scarce for low-temperature calcite in these settings, and consequently, knowledge of the recentpalaeohydrogeological history is limited. Boreholes drilled with triple-tube technique in the upper 1 km of the Palaeoproterozoiccrystalline crust at Laxemar, SE Sweden, have enabled preservation of fragile and potentially recently formed fractureminerals. Earlier investigations of these boreholes have resulted in an extensive set of groundwater chemistry data from variousdepths, and in detailed knowledge of the fracture mineral assemblages (ranging from 1.8 Ga to present). This has made itpossible to identify and sample low-temperature, potentially recently formed, calcite from water-flowing fractures for whichrepresentative groundwater chemical data exists. This, in turn, provides an opportunity to detailed comparisons of fracturecalcite (age span in the order of million years, with possibility of post-glacial contributes) and groundwater (age in the order ofdecades to more than a million year depending on depth) in terms of both isotopic and geochemical properties, giving input tothe understanding of groundwater history, partition coefficients derived in laboratory experiment, and reliability of calcitegeochemistry in terms of representing the actual source fluid composition. In this study, the focus is on trace elements (Fe,Mg, Mn and Sr), stable isotopes and Sr isotopes and, for the groundwater data set, also aquatic speciation with Visual MINTEQ.An optimised step-by-step sample specific analytical procedure was used for the collection of calcite coatings. The methodsused depended on the crystal homogeneity (one or several calcite generations), discerned by detailed SEM-investigations(back-scatter and cathodo-luminescence). 87Sr/86Sr ratios as well as d18O signatures in calcite are in the range expected for theprecipitates from present-day groundwater, or older groundwater with similar composition (except in sections with a considerableportion of glacial water, where calcite definitely is older than the latest glaciation). Stable carbon isotopes in calcitegenerally show values typically associated with HCO3 originating from soil organic matter but at intermediate depth frequentlywith HCO3 originating from in situ microbial anaerobic oxidation of methane (highly depleted d13C). For one ofthe studied metals – manganese – there was a strong correlation between the sampled calcite coatings and hypothetical calcitepredicted by applying laboratory-based partition coefficients (literature data) on groundwater chemistry for sections correspondingto those where the calcites were sampled. This points to temporal and spatial stability in groundwater Mn/Ca ratiosover millions of years, or even more, and show that it is possible to assess, based on laboratory-derived data on Mn partitioning,past groundwater Mn-composition from fracture calcites. For other metals – Fe, Sr, and Mg – which are expected to interact with co-precipitating minerals to a higher degree than Mn, the correlations between measured and predicted calcitewere weaker for various reasons.

  • 348.
    Drake, Henrik
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tullborg, Eva-Lena
    Göteborgs universitet.
    Whitehouse, Martin
    Naturhistoriska riksmuseet.
    Activity of sulfur reducing bacteria in deep bedrock fractures revealed by variability of δ34S in pyrite and dissolved sulphate2013In: Procedia Earth and Planetary Science, ISSN 1878-5220, Vol. 7, p. 228-231Article in journal (Refereed)
    Abstract [en]

    Euhedral pyrite crystals coating 46 granite fractures at depths down to nearly 1 km at Laxemar, Sweden, were analysed for sulfur isotopes (δ34Spyr) by in situ SIMS (secondary ion mass spectrometry) analysis. Most of these fractures had corresponding chemical and isotopic groundwater data, providing a unique opportunity of pyrite-sulfate comparison within the same fracture network. Comparison of the isotopic ratios (δ18O, δ13C, 87Sr/86Sr) of co-genetic calcite with the groundwater showed that the sampled fractures carried pyrite and calcite that are of low-temperature origin, and with some exceptions, possibly precipitated from the present groundwater, or similar pre-modern fluids.

    The δ34Spyr showed huge variations across individual crystals (such as -32 to +73‰) and an extreme overall range (-50‰ to +91‰), which can only be explained by the activity of sulfur reducing bacteria (SRB). The most common sub-grain features were an increase in δ34Spyr with crystal growth related to successively higher δ34SSO4 caused by ongoing SRB activity and Rayleigh fractionation in fractures with low flow. The groundwater δ34SSO4 values (+9 to +37‰) are, in particular in the sulfate-poor waters down to -400 m, higher than the anticipated initial values, and this can also be explained by SRB-related Rayleigh distillation. The δ34SSO4 of the groundwater is, however, lower than that required to produce the highest δ34Spyr values, which may be due to the signal of groundwater in low-flow fractures (carrying 34S-rich sulfate and pyrite) being masked in the water data by high-flow parts of the water-flowing structure carrying abundant and less fractionated sulfate.

  • 349.
    Drugge, Lisbeth
    Luleå tekniska universitet.
    Geochemistry of the Lule River, northern Sweden, before and after regulation2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Lule River is the largest and most important river for hydropower production in Sweden. This river, situated in the northern part of the country, has been regulated since the beginning of the 20th century and is heavily regulated with 15 power stations. The major aim of this study is to quantify the transport of nutrients and other elements in a reservoir, Stora Lulevatten, since knowledge about processes in upstream reservoirs is limited. Monthly sampling of the filtered (<0.22m) phase of river water was performed at the Porjus and Vietas power stations over a period of 15 months. To quantify the effects of river regulation, a geochemical mass balance study was performed. The results show retention of S, K, Si, NO3-N, Fe, PO4-P, Al, Mn and DOC in the reservoir. The study indicates retention levels of 34-43% for Si, Al, Mn, DOC, PO4-P, NO3-N, and for Fe, as much as 68%. A model comparing pre-regulation transport of elements at Porjus power station with present-day transport is presented. The results agree well with the retention of S, DOC, Fe Si, Mn and Al in the reservoir, and thus decreased transport after regulation. One reason for the changed transport is the changed discharge pattern after regulation. Three sediment cores were sampled in the reservoir, and analysed in details for main elements, P and N, and diatom frustules were counted in the sediments. A significantly higher Si/Al ratio could be observed in all three cores after regulation, which correlates with an increased concentration of diatoms in the sediment. The annual retention of non-detrital Si in the sediments as calculated from sediment geochemistry (2138 tonnes Sind/year) is in relatively good agreement with the retention obtained from the mass balance study (3320 tonnes Si/year). A comparison of the background and present-day accumulation of non-detrital Si suggests that the Si retention has increased by 698 tonnes/year after regulation of the Lule River. This increase may be an effect of an increased diatom production in Stora Lulevatten appearing after the construction of the reservoir. Seasonal variations in the geochemical constituents in the regulated Lule River have been studied during an entire year cycle (May 2000 to June 2001) at the Boden power station, near the mouth of the river. Comparing the Si retention in the reservoir with the total transport of Si at Boden, the increased deposition of 698 tonnes Si/year corresponds to a reduction in the Si transport to the Gulf of Bothnia by 2%. The geochemistry of the regulated Lule River is compared with a pristine river, the Kalix River, for which data from a previous study at Luleå University of Technology are available. The results from this comparison show that the transport of Fe (and probably also of P) was found to be clearly decreased due to regulation. The decreased transport of Fe agrees well with the mass balance study, decreased transport after regulation at Porjus and retention of Fe and P in the sediments in Stora Lulevatten. Stora Lulevatten acts as a sink for Fe, Si and P. Considering that Stora Lulevatten is small compared to upstream reservoirs, the total retention is probably larger than that observed in Stora Lulevatten. A result of changed discharge pattern after regulation is that nutrients and other elements reach the Gulf of Bothnia in changed amounts and during different seasons than what would have been the case for an unregulated river.

  • 350.
    Du, Andao
    et al.
    National Research Centre of Geoanalysis, 26 Baiwanzhun Dajie, Beijing.
    Wu, Shuqi
    National Research Centre of Geoanalysis, 26 Baiwanzhun Dajie, Beijing.
    Sun, Dezhong
    National Research Centre of Geoanalysis, 26 Baiwanzhun Dajie, Beijing.
    Wang, Shuxian
    National Research Centre of Geoanalysis, 26 Baiwanzhun Dajie, Beijing.
    Markey, Richard
    AIRIE Group, Department of Earth Resources, Colorado Slate University.
    Stain, Holly
    AIRIE Group, Department of Earth Resources, Colorado Slate University.
    Morgan, John
    AIRIE Group, Department of Earth Resources, Colorado Slate University.
    Malinovskiy, Dmitry
    Preparation and certification of Re-Os dating reference materials: molybdenites HLP and JDC2004In: Geostandards and Geoanalytical Research, ISSN 1639-4488, E-ISSN 1751-908X, Vol. 28, no 1, p. 41-52Article in journal (Refereed)
    Abstract [en]

    Two Re-Os dating reference material molybdenites were prepared. Molybdenite JDC and molybdenite HLP are from a carbonate vein-type molybdenum-(lead)-uranium deposit in the Jinduicheng-Huanglongpu area of Shaanxi province, China. The samples proved to be homogeneous, based on the coefficient of variation of analytical results and an analysis of variance test. The sampling weight was 0.1 g for JDC and 0.025 g for HLP. An isotope dilution method was used for the determination of Re and Os. Sample decomposition and pre- concentration of Re and Os prior to measurement were accomplished using a variety of methods: acid digestion, alkali fusion, ion exchange and solvent extraction. Negative thermal ionisation mass spectrometry and inductively coupled plasma-mass spectrometry were used for the determination of Re and 187Os concentration and isotope ratios. The certified values include the contents of Re and Os and the model ages. For HLP, the Re content was 283.8 ± 6.2 µg g-1, 187Os was 659 ± 14 ng g-1 and the Re-Os model age was 221.4 ± 5.6 Ma. For JDC, the Re content was 17.39 ± 0.32 µg g-1, 187Os was 25.46 ± 0.60 ng g-1 and the Re-Os model age was 139.6 ± 3.8 Ma. Uncertainties for both certified reference materials are stated at the 95% level of confidence. Three laboratories (from three countries: P.R. China, USA, Sweden) joined in the certification programme. These certified reference materials are primarily useful for Re-Os dating of molybdenite, sulfides, black shale, etc. .

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