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  • 51.
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Suspended particulate matter, sedimentation and early diagenetic processes in the Kalix River estuary, northern Sweden1996Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Many important reactions controlling the transfer of elements from the continents to coastal waters and the oceans are taking place in estuaries. For many elements, estuaries can act as filters, capable of reducing the river load of dissolved and particulate elements to the oceans. Although sedimentation is an important process in estuaries, early diagenetic processes in sediments may be responsible for the remobilization of redox-sensitive elements back into estuarine waters. This thesis focuses on the behaviour of suspended and settling particulate Fe - Mn oxides and organic matter in the stratified, low-salinity (< 3‰) Kalix River estuary. In addition, the early diagenetic cycling of Fe, Mn, organic C and trace metals was also studied. Samples of the dissolved (< 0.45 μm) and suspended phase were collected along vertical profiles at three stations in the estuary. Settling particulate matter was collected by the use of sediment traps. Pore-water and solid phase sediment data were used to study early diagenetic processes. The estuary appears to be relatively inefficient as a trap for river transported, particulate, oxide- and organic-associated elements. Suspended, slow-settling particles rich in Fe - Mn oxides and organic matter to a large extent are flushed through the estuary in the seaward flowing surface water. Organic matter is an important carrier of Cu, which appears to be due in part to biological uptake of Cu. Flocculation of dissolved Fe, Si and Al is of little or no significance, while Mn is desorbed from suspended particles early in the estuarine mixing of freshwater and brackish water. A study of the varved, undisturbed sediments deposited in the central part of the estuary shows that the deposition of trace metals has decreased since the late 1970's. Despite active post-depositional redox cycling of Fe and Mn, efficient oxidation processes in the surface sediment prevent diffusion of dissolved Fe and Mn back into the water column. Reduction/ dissolution of Fe oxides is a slow process, resulting in burial of Fe oxides in permanently deposited, anoxic sediments. Post-depositional mobilization of trace metals in the bottom sediment is controlled by the type of carrier phase and the redox conditions in the sediment. The post-depositional mobility of trace metals is low - moderate, except for As, which is associated with redox-sensitive Fe oxides. Copper is associated with with labile organic matter, and early diagenetic remobilization of Cu appears to be entirely controlled by oxic decomposition of organic matter close to the sediment - water interface.

  • 52.
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Trace metal transport into the Bothnian Bay by particulate Fe-Mn oxides and organic matter1996Inngår i: Jubilee issue: short papers and abstracts for the Jubilee meeting "Current problems, ideas and results in geology" : Stockholm 16th-18th October 1996 at the celebration of the 125th anniversary of the Geological society of Sweden / [ed] Björn Sundquist, Geologiska föreningen , 1996, s. 91-Konferansepaper (Fagfellevurdert)
  • 53.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Andersson, Per S.
    Swedish Museum of Natural History.
    Strontium isotopic composition of modern and Holocene mollusc shells as a palaeosalinity indicator for the Baltic Sea2006Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 232, nr 1-2, s. 54-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The 87Sr/86Sr isotope ratio in subfossil carbonate mollusc shells from raised-beach sediments is used as a palaeosalinity indicator for the Baltic Sea. The main purpose is to demonstrate the applicability of the method in a formerly glaciated area, using 87Sr/86Sr ratios found in modern shells (Mytilus edulis, Macoma baltica, and Radix balthica) to elucidate the parameters and conditions to be used for palaeosalinity determinations based on subfossil shells. Proxy salinity data are calculated assuming that the Sr concentration in Baltic Sea water is controlled by a two-component, conservative mixing between seawater and river water. Based on replicate determinations of the 87Sr/86Sr ratio in modern shells, proxy salinity data can be quantified with a relative precision of better than ± 5% for salinities up to ≈ 10‰. Comparison with measured, present-day salinities indicates that the accuracy is generally better than ± 5% for the proxy data. With this precision and accuracy, the present-day salinity differences between the major Baltic sub-basins (Bothnian Bay, Bothnian Sea, and Baltic Proper) can be detected. Palaeosalinities were determined using subfossil shells (M. edulis and M. baltica) with calibrated 14C ages of 6770-3070 cal BP. The shell deposits occur from 65 m a.s.l. down to the present-day sea level. The palaeosalinities determined for the Bothnian Bay (4.8-10.3‰) and the Bothnian Sea (7.3-10.3‰) are in good agreement with earlier estimates of the maximum Littorina Sea stage palaeosalinity in these sub-basins (8-10‰). At one locality, two different shell species from the same shell deposit were dated (M. edulis and M. baltica). The shells differed in age by 460 ± 70 14C years, a possible indication that the ecological conditions at a locality may have been favourable to different faunas at different times.

  • 54.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Andersson, P.S.
    Swedish Museum of Natural History.
    A Holocene strontium isotope record of palaeosalinity for the Littorina Sea stage of the Baltic Sea2007Inngår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 71, nr 15S, s. A1108-Artikkel i tidsskrift (Annet vitenskapelig)
  • 55.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Andersson, P.S.
    Laboratory for Isotope Geology. Swedish Museum of Natural History, Stockholm.
    Late Holocene freshening of the Baltic Sea derived from high-resolution strontium isotope analyses of mollusk shells2011Inngår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 39, nr 2, s. 187-190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Strontium isotopic composition (87Sr/86Sr) data from subfossil 14C-dated mollusk shells in raised beach sediments are used as a paleosalinity proxy in the brackish Baltic Sea, the precision (±5%) and accuracy (±0.7‰) of the method being judged from replicate analyses of modern shells. Paleosalinity data with an average time resolution of ~200 yr for the period 7130-2775 calibrated 14C yr B.P. indicate maximum surface salinities of 10‰-11‰, 11‰-12‰, and 12‰-13‰ for the Bothnian Bay, Bothnian Sea, and Baltic Proper (the three major Baltic subbasins). The relative salinity differences between the basins were small (≤30%) compared to the as much as eightfold present-day relative salinity differences (Bothnian Bay 1‰-3‰; Bothnian Sea 4‰-5‰; Baltic Proper 6‰-8‰). Late Holocene freshening (ca. 3000 calibrated 14C yr B.P. to present) is most pronounced in the northernmost subbasin, the Bothnian Bay, consistent with the absence of a permanent halocline, sequestering of phosphorus in well-oxygenated bottom sediments, and phosphorus limitation of primary production in the present-day Bothnian Bay. This study suggests that paleosalinity data may be crucial to improving our understanding of the possible effects of any future, climate-induced freshening of the Baltic Sea

  • 56.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Chlot, Sara
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Herbert, Roger
    Department of Earth Sciences, Uppsala University.
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Nitrogen effluents from mine sites: environmental effects and removal of nitrogen in recipients2011Konferansepaper (Annet vitenskapelig)
  • 57.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Chlot, Sara
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Sedimentary records of δ13C, δ15N and organic matter accumulation in lakes receiving nutrient-rich mine waters2014Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 485-486, s. 205-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic C and total N concentrations, C/N ratios, δ15N and δ13C values in 210Pb-dated sediment cores were used to reconstruct historical changes in organic matter (OM) accumulation in three Swedish lakes receiving nutrient-rich mine waters. Ammonium-nitrate-based explosives and sodium cyanide (NaCN) used in gold extraction were the major N sources, while lesser amounts of P originated from apatite and flotation chemicals. The software IsoSource was used to model the relative contribution of soil, terrestrial and littoral vegetation, and phytoplankton detritus in the lake sediments. In one lake the IsoSource modelling failed, suggesting the presence of additional, unknown OM sources. In two of the lakes sedimentary detritus of littoral vegetation and phytoplankton had increased by 15–20% and 20–35%, respectively, since ~ 1950, when N- and P-rich mine waters began to reach the lakes. Today, phytoplankton is the dominating OM component in these lake sediments, which appears to be a eutrophication effect related to mining operations. Changes in the N isotopic composition of biota, lake water, and sediments related to the use of ammonium-nitrate-based explosives and NaCN were evident in the two studied systems. However, N isotope signals in the receiving waters (δ15N ~ + 9‰ to + 19‰) were clearly shifted from the primary signal in explosives (δ15N–NO3 = + 3.4 ± 0.3‰; δ15N–NH4 = − 8.0 ± 0.3‰) and NaCN (δ15N = + 1.1 ± 0.5‰), and direct tracing of the primary N isotope signals in mining chemicals was not possible in the receiving waters. Systems where mine waters with a well known discharge history are a major point source of N with well-defined isotopic composition should, however, be suitable for further studies of processes controlling N isotope signatures and their transformation in aquatic systems receiving mine waters.

  • 58.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Davison, William
    Lancaster University.
    Size and density distribution of sulfide-producing microniches in lake sediments2007Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 41, nr 23, s. 8044-8049Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The technique of diffusive gradients in thin films (DGT) with measurements by computer-imaging densitometry (CID) was used to study the in situ, two-dimensional distribution of sulfide-producing microniches in sediments from a eutrophic lake (Esthwaite Water, UK). The DGT-CID technique precipitates and immobilizes the net pore-water flux of dissolved sulfide as black Ag2S by reaction with a AgI binding gel. The mass of accumulated sulfide is then determined from a scanned grayscale image of this gel. DGT probes deployed in laboratory mesocosms of homogeneously mixed sediment, then analyzed at high spatial resolution (~0.1 mm), showed that apparent niche areas (operationally defined by DGT-CID) were <1 mm2 for 30% of the niches. In eight DGT probes deployed in undisturbed sediment cores, the proportion of microniche-related sulfide flux was ≥1–8% of the total horizontal net pore-water flux of sulfide. This study suggests that microniches that introduce local redox gradients are common in sediments. As fluxes within these microenvironments can considerably exceed background values, consideration of the dynamics of the biogeochemical processes occurring at these sites is likely to be key to improving our understanding of early diagenesis. Measurement procedures and three-dimensional reaction-transport models should be designed with the aim of furthering understanding of the complexities associated with locally supplied particles of reactive organic matter.

  • 59.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Davison, William
    Lancaster University.
    Nowell, Geoff
    Durham University.
    Pearson, Graham
    Durham University.
    Bacterial sulphate reduction and sulphur isotope fractionation in sediment microniches2009Konferansepaper (Annet vitenskapelig)
  • 60.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Ebenå, Gustav
    Department of Biology, Linköping University.
    Landin, Jan
    Department of Biology, Linköping University.
    Potential biogeochemical and ecological development of a flooded tailings impoundment at the Kristineberg Zn-Cu mine, northern Sweden2004Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 333, nr 1-3, s. 249-266Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The potential short-term (≤102 years) and long-term (>102 years) biogeochemical and ecological effects of diverting stream water (pH 4.9-6.7) into a limed, flooded tailings impoundment (pH 8-12) were studied by combining geochemical and biological data. In the long-term perspective, the successional development of lakes was used as a natural analogue. Based on the vertical distribution of temperature and total dissolved solids (TDS<0.22 μm), the impoundment can be characterised as a continuous/discontinuous cold polymictic lake, with holomictic summer circulation. A re-inoculation study indicated that the growth of autotrophic, aerobic bacteria (presumably Acidithiobacillus ferrooxidans) presently is inhibited by the high pH in the impoundment. In a short-term perspective, termination of liming and diversion of stream water into the impoundment will result in a complex interplay between physical, biogeochemical and ecological effects. A reduced vertical mixing of the ≈2-m-deep water column, dissolution of calcite and gypsum (compounds of a sludge formed in the impoundment) and an enhanced microbiological activity are major expected effects. The dissolution of calcite may act as a pH buffer and result in metal remobilisation from the sludge. Excluding autochthonous organic matter produced in the impoundment, streamwater input of suspended matter and formation of settling flocculants are expected to result in a sediment accumulation rate of ≈1.5 mg cm-2 year-1 (1.6-3.3 cm/102 years). Settling allochthonous organic C (0.15-0.30 mg C cm-2 year-1) may serve as an oxygen barrier and as a reservoir of organic compounds capable of driving redox reactions. In a long-term perspective, a hydroseral development into a wetland/peatland can be expected, with a bog lake, poor fen or flat bog as final stage. This development presupposes a decreasing pH when liming is terminated and stream water is diverted into the impoundment. It also assumes that the impoundment will be similar to an acidified lake, and that the succession is driven by Sphagnum colonizing the impoundment. If the hydrological conditions/water level is affected (e.g., by climatic changes or a dam failure), a terrestrialization culminating in coniferous forest on peat soil may occur.

  • 61.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Holmström, Henning
    Öhlander, Björn
    Andersson, Anders
    Flooding of sulphidic mine tailings as a remediation method at Kristineberg, northern Sweden2001Inngår i: Securing the future: Proceedings of the International Conference on Mining and the Environment, Skelleftea, June 25-July 1, 2001, Stockholm: Swedish Mining Association , 2001, Vol. 2, s. 906-914Konferansepaper (Fagfellevurdert)
  • 62.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Ingri, Johan
    Early diagenesis of arsenic in sediments of the Kalix River estuary, northern Sweden1995Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 125, nr 3-4, s. 185-196Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solid-phase As, Fe, Mn, S and Al and pore-water total As, Fe, Mn and S have been determined for two cores from the Kalix River estuary. At the same station, the depositional flux of arsenic was measured sediment traps. Fe(III)-oxides persist in the anoxic zone of the sediment and act as a carrier for arsenic down to depths of 10-15 cm. The release of arsenic into the pore water is controlled by the reduction/dissolution of these oxides. As a result, internal cycling of arsenic, i.e. upward diffusion in pore water, re-adsorption onto Fe(III)-oxides in the oxidized surface layer and reburial occurs in the uppermost 10-15 cm. At the base of the arsenic cycling zone, solid-phase arsenic maxima (160-170 μg g-1) of probable diagenetic origin occur. The quantity of arsenic diffusing back towards the oxidized surface layer (2.2 μg cm-2 yr-1 As) is close to 75% of the quantity of arsenic being deposited due to sedimentation (2.9 μg cm-2 yr-1 As). However, a mass balance for the surface layer indicates that re-adsorption of arsenic onto Fe(III)-oxides may effectively prevent diffusion of dissolved arsenic back into the overlying water column. It is concluded that the interpretation of sedimentary arsenic profiles may be severely complicated due to post-depositional migration of arsenic

  • 63.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Ingri, Johan
    Redox cycling of iron and manganese in sediments of the Kalix River estuary, northern Sweden1996Inngår i: Aquatic geochemistry, ISSN 1380-6165, E-ISSN 1573-1421, Vol. 2, nr 2, s. 185-201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iron and manganese redox cycling in the sediment - water interface region in the Kalix River estuary was investigated by using sediment trap data, pore-water and solid-phase sediment data. Nondetrital phases (presumably reactive Fe and Mn oxides) form substantial fractions of the total settling flux of Fe and Mn (51% of Fetotal and 84% of Mntotal). A steady-state box model reveals that nondetrital Fe and Mn differ considerably in reactivity during post-depositional redox cycling in the sediment. The production rate of dissolved Mn (1.6 mmol m-2 d-1) exceeded the depositional flux of nondetrital Mn (0.27 mmol m-2 d-1) by a factor of about 6. In contrast, the production rate of upwardly diffusing pore-water Fe (0.77 mmol m-2 d-1) amounted to only 22% of the depositional flux of nondetrital Fe (3.5 mmol m-2 d-1). Upwardly diffusing pore-water Fe and Mn are effectively oxidized and trapped in the oxic surface layer of the sediment, resulting in negligible benthic effluxes of Fe and Mn. Consequently, the concentrations of nondetrital Fe and Mn in permanently deposited, anoxic sediment are similar to those in the settling material. Reactive Fe oxides appear to form a substantial fraction of this buried, non-detrital Fe. The in-situ oxidation rates of Fe and Mn are tentatively estimated to be 0.51 and 0.16-1.7 mol cm-3 d-1, respectively

  • 64.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Nowell, Geoff M.
    Durham University.
    Davison, William
    Lancaster University.
    Pearson, D. Graham
    Durham University.
    High-resolution measurements of sulphur isotope variations in sediment pore-waters by laser ablation multicollector inductively coupled plasma mass spectrometry2012Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 291, nr 1, s. 278-285Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel combination of the technique of diffusive gradients in thin films (DGT) and laser ablation high-resolution multicollector inductively coupled plasma mass spectrometry was developed to study sulphur isotope variations of dissolved pore-water sulphide in freshwater and marine sediments. The technique enables two-dimensional mapping of isotopic variations (δ34S) in dissolved sulphide captured as solid Ag2S in DGT polyacrylamide gels. Measurements can be performed at a spatial resolution (~ 100 μm) relevant to microbiological processes and formation of individual iron sulphide grains in surface sediments. Values of δ34S measured in BaSO4–DGT gel isotope standards (δ34S = 9.28 ± 0.36‰ to 9.33 ± 0.57‰) are within 1‰ of the accepted value determined with conventional analytical techniques (δ34S = 10.13 ± 0.29‰). Sulphur isotope measurements were performed in sediments from a eutrophic lake (Esthwaite Water, UK) contained in laboratory mesocosms. Bacterial sulphate reduction and sulphide formation in this sediment are predominantly localized to discrete, mm-sized microniches, where oxidation of labile organic matter such as fresh algae and faecal pellets drives the reduction of sulphate. The results emphasize the importance of microniches as localized, highly dynamic reaction sites in sediments, where significant shifts in δ34S of up to + 20‰ relative to the local background were measured across microniches. The improved spatial resolution for pore-water sulphur isotope measurements, compared to that of conventional sampling and analytical techniques, is essential for improving our understanding of the global biogeochemical cycling of sulphur as well as trace metal–sulphide interactions in modern sediments.

  • 65.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Peinerud, Elsa
    Natural attenuation of metals at mine waste sites: the role of flocculation and particle dynamics in natural and engineered systems2003Rapport (Annet vitenskapelig)
  • 66.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Roos, Per
    Varved sediments in the Kalix River estuary, northern Sweden1994Inngår i: Aqua Fennica, ISSN 0356-7133, Vol. 24, nr 2, s. 163-169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two virtually undisturbed cores collected by using the crust-freezing technique revealed the occurrence of varved sediments in the Kalix River estuary. Sedimentation rates were determined by super(137)Cs measurements, varve-counting and also by sediment traps. Each varve consists of a grey, predominantly clastic spring flood layer and a brown layer relatively rich in Fe (III) oxides, deposited during the rest of the year. The varve thickness is 5-13 mm, corresponding to a sedimentation rate of 96-227 mg dry sediment/cm super(2)/yr. Fall-out from the Chernobyl accident resulted in a 7-10 fold increase of super(137)Cs in the layer deposited during the summer and autumn of 1986. During the period 1975-1991, one or two major resuspension events occurred in the estuary

  • 67.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Roos, Per
    Lund University.
    Gunneriusson, Lars
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Ingri, Johan
    Holmström, Henning
    Envipro Miljöteknik AB, Linköping.
    Early diagenesis and isotopic composition of lead in Lake Laisan, northern Sweden2002Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 189, nr 3-4, s. 183-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Water column (dissolved/suspended phase, sediment traps) and sediment data (pore-water, solid-phase sediment) were combined with stable Pb and 210Pb isotope data to trace the early diagenetic behaviour and geochemical cycling of Pb in Lake Laisan, a lake which has received large quantities of anthropogenic Pb since the early 1940s. Early diagenetic remobilisation of Pb is indicated by a subsurface pore-water Pb maximum (120 μg l-1) in the oxic surface layer of the sediment, where the solid-phase Pb concentration is 3400-4600 μg g-1. The remobilisation of Pb appears to be caused by a pH-controlled desorption of Pb from solid-phase sediment, which is consistent with a model describing surface complexation of Pb(II) on hydrous goethite surfaces. The diffusive Pb flux from the subsurface pore-water maximum towards the sediment surface (36 μg cm-2 year-1) exceeds the depositional Pb flux (8.6 μg cm-2 year-1) by approximately a factor of four, indicating that Pb is highly mobile in the sediment. Stable Pb isotope data and a mass balance calculation suggest that Pb diffusing upwards is, to a large extent, trapped in the surface sediment. Lead that may diffuse into the slightly alkaline lake water appears to be efficiently sorbed to suspended particulate matter, resulting in low dissolved Pb concentrations in the water column (0.040-0.046 μg l-1). Sorption of Pb to suspended particulate matter is consistent with the elevated suspended particulate Pb concentrations in the hypolimnion (3800-4000 μg g-1), and the fact that the stable Pb isotopic compositions of suspended matter and pore-water are similar.

  • 68.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Shcherbakova, Elena
    Carlsson, Erik
    Friedrich-Schiller Univärsität, Jena.
    Holmström, Henning
    Envipro Miljöteknik AB, Linköping.
    Öhlander, Björn
    Laboratory study of calcite-gypsum sludge-water interactions in a flooded tailings impoundment at the Kristineberg Zn-Cu mine, northern Sweden2005Inngår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 20, nr 5, s. 973-987Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to liming of acid mine drainage, a calcite–gypsum sludge with high concentrations of Zn (24,400 ± 6900 μg g−1), Cu (2840 ± 680 μg g−1) and Cd (59 ± 20 μg g−1) has formed in a flooded tailings impoundment at the Kristineberg mine site. The potential metal release from the sludge during resuspension events and in a long-term perspective was investigated by performing a shake flask test and sequential extraction of the sludge. The sequentially extracted carbonate and oxide fractions together contained 97% of the total amount of Cd, Co, Cu, Ni, Pb and Zn in the sludge. The association of these metals with carbonates and oxides appears to result from sorption and/or coprecipitation reactions at the surfaces of calcite and Fe, Al and Mn oxyhydroxides forming in the impoundment. If stream water is diverted into the flooded impoundment, dissolution of calcite, gypsum and presumably also Al oxyhydroxides can be expected during resuspension events. In the shake flask test (performed at a pH of 7–9), remobilisation of Zn, Cu, Cd and Co from the sludge resulted in dissolved concentrations of these metals that were significantly lower than those predicted to result from dissolution of the carbonate fraction of the sludge. This may suggest that cationic Zn, Cu, Cd and Co remobilised from dissolving calcite, gypsum and Al oxyhydroxides were readsorbed onto Fe oxyhydroxides remaining stable under oxic conditions. In a long-term perspective (102 a), 97% of the Cd, Co, Cu, Ni, Pb and Zn content of the sludge potentially is available for release by dissolution of calcite and reductive dissolution of Fe oxyhydroxides if the sludge is subject to a soil environment with lower dissolved Ca concentrations, pH and redox than in the impoundment.

  • 69.
    Widerlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Shcherbakova, Elena
    Forsberg, Jerry
    Holmström, Henning
    Envipro Miljöteknik AB, Linköping.
    Öhlander, Björn
    Laboratory simulation of flocculation processes in a flooded tailings impoundment at the Kristineberg Zn-Cu mine, northern Sweden2004Inngår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 19, nr 10, s. 1537-1551Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A laboratory mixing experiment was performed to simulate the flocculation processes that can be expected when natural stream water mixes with the saline water in flooded tailings impoundments. Mixing plots where dissolved (<0.22 μm) Ca, Mg, Na, K, S and Si were plotted vs. a conservative mixing index revealed a conservative mixing behaviour for these elements. Similar plots for dissolved Fe, Mn, Al and total organic C (TOC) showed that dissolved Fe and Al flocculated within 24 h after the mixing of the waters. Dissolved Mn was removed from solution 13-98 days after mixing, presumably due to the oxidation of Mn2+. Removal of TOC could not be detected in the mixing bottles. However, the flocculants that settled in the mixing bottles (1.7-3.4 mg flocs L-1 of stream water) contained 18 wt% C and 14-19 wt% acid-leacheable Fe. Organic C and Fe oxyhydroxides thus appear to form substantial fractions of the flocculants. If stream water is diverted through tailings ponds as part of a remediation programme, flocculation processes are likely to contribute to natural sedimentation in the pond. However, the relative contribution from flocculated particulate matter may be significant only when the stream-water transport of suspended matter into the impoundment is low (<10-15 mg L-1). Trace metal uptake in the flocculants that settled in the mixing bottles resulted in removal of Cd (0.024-0.028 μg L-1), Co (0.15-0.17 μg L-1), Cu (1.8-3.5 μg L-1) and Zn (15-29 μg L-1) from the dissolved phase. Relative to the dissolved trace metal concentrations in the tailings pond water used in the experiment (Cd=0.435-0.438 μg L-1; Co=0.738-0.763 μg L-1; Cu=3.16-5.05 μg L-1; Zn=26.6-32.6 μg L-1), the trace metal uptake exceeded 50% of these concentrations only for Cu and Zn.

  • 70.
    Öhlander, Björn
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Drugge, L.
    Widerlund, Anders
    Ingri, Johan
    Changed transport of weathering products after river regulation: the Lule River, northern Sweden2004Inngår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 68, nr 11, s. 31-Artikkel i tidsskrift (Annet vitenskapelig)
  • 71.
    Öhlander, Björn
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Land, Magnus
    Mistra Council for Evidence-based Environmental Management (EviEM), The Royal Swedish Academy of Sciences.
    Ingri, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Mobility and transport of Nd isotopes in the Vadose zone during weathering of granitic till in a boreal forest2014Inngår i: Aquatic geochemistry, ISSN 1380-6165, E-ISSN 1573-1421, Vol. 20, nr 1, s. 1-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a broad correlation between the εNd values for rivers (including both the water and the particulate material it carries) and the age of the source terrain. This paper presents Nd isotope distribution data for soil, soil water, groundwater, and stream water samples gathered in a small catchment in northern Sweden. The results show that the release of Nd and Sm from boreal forests into streams and, eventually, into the oceans is more complicated than previously realized. The weathering of till causes changes in both the Nd isotopic composition and Sm/Nd ratios. Both the Sm/Nd ratio and εNd were higher in strongly weathered soils horizons than in less weathered till, since minerals with high Sm/Nd ratios were, on average, more resistant to weathering than those with low Sm/Nd ratios. In contrast to the situation for the main minerals and the major elements, the weathering of rare earth elements (REE) was not restricted to the E-horizon: the measured REE concentrations continued to increase with depth in the C-horizon. In addition, REE released by weathering in the upper parts of the soil profile were partly secondarily retained at deeper levels. Therefore, the dissolved Nd released by weathering in the upper soil horizons was trapped and did not enter the groundwater directly. Rather, the Nd in the groundwater largely originated from weathering within the groundwater zone. However, this was not the only source of Nd in the stream water. The Nd isotope composition and Sm/Nd ratio were determined by the mixing between of Nd and Sm in the groundwater and REE-carrying organic material washed out of the soil profile. The groundwater close to the stream reaches the upper soil horizons during high discharge events such as snowmelts, and organic matter carrying Nd and Sm is washed out of the soils and thus released into the stream. Therefore, the Nd exported from catchment is derived from both the weathering within the groundwater zone, and the organic matter washed out from the soil. If longer timescales with more advanced weathering stages in the groundwater zone are considered, it cannot be ruled out that there will be a shift towards more radiogenic values in the exported Nd. Recorded shifts in the Nd isotopic composition in the ocean may thus not only reflect changed source regions, but also the weathering history of the same source region

  • 72. Öhlander, Björn
    et al.
    Land, Magnus
    Luleå tekniska universitet.
    Ingri, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Mobility of rare earth elements during weathering of till in northern Sweden1996Inngår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 11, nr 1-2, s. 93-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Continuous, volume-controlled sampling from the surface down to a depth of 130 cm was conducted at two stations on weathered till (typic haplocryods). All the samples were analysed for major and trace elements including the rare earth elements (REE). Eight thousand seven hundred years of weathering since the glacial ice left the area, has resulted in a strong depletion of REE in the E-horizon. This loss decreases as atomic number increases, so that 80-85% of the La and 54-60% of the Yb have been lost. Europium has been lost to a greater degree than have the neighbouring elements. Possible explanations for the release of REE are: weathering of common silicates such as hornblende and epidote (and plagioclase in the case of Eu); weathering of apatite; weathering of rare but REE-rich minerals such as allanite and monazite; and release of REE adsorbed on clay minerals. Further studies on various size fractions and minerals are needed to quantify the importance of the various possible mechanisms of REE release. The release of REE continues within and below the Bs1-horizon, but the results from one station show that light REE can be enriched in the Bs1-horizon. This secondary enrichment could be caused by adsorption on secondary oxy-hydroxides, on clay minerals or on organic material. However, the net result of the weathering is that all REE have been released to the groundwater.

  • 73. Öhlander, Björn
    et al.
    Lindvall, Manfred
    Widerlund, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Holmström, Henning
    Carlsson, Erik
    Peinerud, Elsa K
    Correge, Olivier
    A system approach to mine waste remediation, the Kristineberg mine, northern Sweden2003Inngår i: Acid rock drainage: application and sustainability of technologies : sixth international conference ; 14 - 17 July 2003, Cairns, Queensland, Australia ; proceedings, Carlton, Victoria: The Australian Institute of Mining and Metallurgy , 2003, s. 81-92Konferansepaper (Fagfellevurdert)
  • 74.
    Öhlander, Björn
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Widerlund, Anders
    Holmström, Henning
    Ingri, Johan
    MiMi – Field studies and characterisation: state-of-the-art-report1998Rapport (Annet vitenskapelig)
  • 75. Österlund, Helene
    et al.
    Chlot, Sara
    Faarinen, Mikko
    ALS Laboratory Group, Luleå.
    Widerlund, Anders
    Rodushkin, Ilya
    Ingri, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Baxter, Douglas
    Simultaneous measurements of As, Mo, Sb, V and W using a ferrihydrite diffusive gradients in thin films (DGT) device2010Inngår i: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 682, nr 1-2, s. 59-65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ferrihydrite-backed DGT (diffusive gradients in thin films), recently developed for arsenic and phosphate measurements was, for the first time, characterized with respect to molybdate, antimonate, vanadate and tungstate determination. Arsenate was included in the characterization to allow comparison with literature data and thus provide quality control of the measurements. In addition to laboratory experiments, field measurements were carried out in a natural stream in northern Sweden affected by mine drainage. It was shown that ferrihydrite-DGT is suitable for simultaneous determination of labile arsenic, molybdate, antimonate, vanadate and tungstate over a wide pH range. Diffusion coefficients were estimated using two different methods; diffusion cell and direct uptake to DGT devices in synthetic solutions. Estimations of the coefficients using the direct uptake method were performed between pH 4 and 8. The results from the two methods agreed well irrespective of pH, except for molybdate and antimonate that showed decreased values at pH 8. Adsorption of the analytes to ferrihydrite gel discs was rapid at all pH values. However, there was a tendency toward lower adsorption affinity for antimonate compared to the other anions. 100% recovery of accumulated analytes was achieved through complete dissolution of the ferrihydrite adsorbent using 1.4 mol L-1 HNO3 with 0.1 mol L-1 HF. From field sampling it was concluded that the opportunities for accurate antimonate and molybdate determination decrease at pH ≥8.7. DGT labile concentrations were generally lower than dissolved concentrations. Relatively lower DGT concentrations, compared to dissolved (<0.45 μm), were observed under a period when ferric oxide precipitations were detected on the DGT protective filter.

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