| 11. |
- Carlsson, E., et al.
(författare)
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Sequential extraction of sulfide-rich tailings remediated by the application of till cover, Kristineberg mine, northern Sweden
- 2002
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 299:1-3, s. 207-226
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Tidskriftsartikel (refereegranskat)abstract
- A sequential extraction has been carried out on sulfide-rich mine tailings. The purpose was to investigate how elements released by oxidation are secondarily retained in the tailings and the possible consequences of the remediation. After investigating the solid tailings, seven samples were chosen for sequential extractions. Two samples were oxidised, situated just above the oxidation front, two samples from just below the former oxidation front with increased concentrations of several elements, two unoxidised samples were from an intermediate depth, and the deepest sample was from the tailings-peat boundary at the bottom of the impoundment. Five phases were extracted: adsorbed/exchangeable/carbonate, labile organics, amorphous Fe-oxyhydroxides/Mn-oxides, crystalline Fe-oxides, and organics/sulfides. The addition from dried porewater to the extracted fractions has been calculated and considered as minor. In the oxidised tailings, the sulfide fraction still dominates for elements such as Fe, S, Cd, Co, Cu, Hg and Zn, although the concentrations are low compared to the unoxidised tailings. Generally, the second most important fraction is the adsorbed/exchangeable/carbonate fraction. Below the oxidation front, the sulfide content of the tailings sharply increases. In the secondary enrichment zone, the total element concentrations increase compared with the deeper unoxidised samples, mainly due to secondary retention. For some elements, secondary retention is greater than the total amount extracted for the deeper unoxidised samples. In the secondary enrichment zone the adsorbed/exchangeable/carbonate fraction represents approximately 20 wt.% or more for Cd, Co, Mn, Ni and Zn. The amorphous iron oxyhydroxide or the crystalline iron oxide fractions are less important at this level, although for As, Ba and Cu the amorphous iron oxyhydroxide fraction represents up to 20 wt.%. At the lower border of the enrichment zone, the total concentration for most metals is lower, but the importance of the adsorbed/exchangeable/carbonate fraction is further enhanced for Cd, Cu, Ni and Zn. These elements have 35-60 wt.% of the total amount from this fraction. For As, Cd, Cu, Ni and Pb, the secondary fractions extracted (extractions A-D) represent between 60 and 80 wt.% of the total content. At greater depth in the impoundment the relative importance of the adsorbed/exchangeable/carbonate fraction decreases, whilst the importance of amorphous iron oxyhydroxide and crystalline iron oxide fractions increases. The adsorbed/exchangeable/carbonate fraction is the most easily remobilised fraction. A raised groundwater table previously situated below the enrichment zone may result in the release of secondarily retained metals. © 2002 Elsevier Science B.V. All rights reserved.
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| 12. |
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| 13. |
- Danilov, Roman, et al.
(författare)
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The use of epiphyton and epilithon data as a base for calculating ecological indices in monitoring of eutrophication in lakes in central Sweden
- 2000
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 248, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- Eutrophication was monitored with the aid of one similarity and seven diversity indices in the lakes of different trophic levels (eutrophic, mesotrophic and oligotrophic) in central Sweden. The ecological indices were applied separately to epiphyton and epilithon communities. Epiphyton turned out to be inappropriate for assessing eutrophication in the lakes studied. On the other hand, Hurlbert's, Simpson's and the similarity indices turned out to be promising environmental tools when applied to the data of epilithon.
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| 14. |
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| 15. |
- Engwall, Magnus, 1965-, et al.
(författare)
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Fate of Ah-receptor agonists in organic household waste during anaerobic degradation : estimation of levels using EROD induction in organ cultures of chick embryo livers
- 2002
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 297:1-3, s. 105-108
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Tidskriftsartikel (refereegranskat)abstract
- The fate of 7-ethoxyresorufin O-deethylase (EROD)-inducing compounds in source-separated organic household waste subject to anaerobic degradation (i.e. mesophilic/thermophilic anaerobic treatment) was investigated using organ cultures of embryonic chicken livers from fertilised hen eggs. This bioassay reflects the combined effect of all EROD-inducing, possibly dioxin-like compounds in a sample, including chemicals that are seldom or never analysed. All samples tested induced EROD in the bioassay, indicating the presence of dioxin-like compounds. In the anaerobic processes, the amounts of acid-resistant EROD-inducing compounds coming out of the reactors were considerably higher than the incoming amounts, especially for the low-temperature (mesophilic) process. This apparent production of EROD-inducing compounds may be due to de novo synthesis or to an increase in the EROD-inducing potency of the compounds in the material.
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| 16. |
- Flink, P, et al.
(författare)
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Statistical analysis of hyperspectral data from two Swedish lakes
- 2001
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 268:1-3, s. 155-169
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Tidskriftsartikel (refereegranskat)abstract
- CASI data has been collected from two lakes in Sweden. In this paper. some statistical properties of CASI spectral data have been discussed. Principal component analysis is used for assessing the dimensionality of the data and the principal components wer
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| 17. |
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| 18. |
- Funseth, Eva, et al.
(författare)
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Effects of coxsackievirus B3 infection on the acute-phase protein metallothionein and on cytochrome P-4501A1 involved in the detoxification processes of TCDD in the mouse
- 2002
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 284:1-3, s. 37-47
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Tidskriftsartikel (refereegranskat)abstract
- During acute infections, the synthesis of acute-phase proteins and other proteins participating in the host defence are stimulated in the liver and kidney. In previous studies of coxsackievirus B3 (CB3) infection in mice, we found that cadmium (Cd) accumulates in the kidney, whereas 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) accumulates in the liver. To study if CB3 infection affects the synthesis of the Cd-binding protein metallothionein (MT) and the TCDD-binding/detoxifying cytochrome P-450 (CYP-450) isozyme CYP1A1, the basal and TCDD-induced levels of serum MT and liver CYP1A1 isozyme were determined in healthy and CB3-infected A/J mice. Furthermore, because interferons affect CYP450 activity, the serum levels of the interferons alpha (IFN-alpha) and -beta (IFN-beta) were measured in CB3-infected mice and in mice treated with the interferon-inducer polyinosinic/polycytidylic acid (poly I/C). Virus or poly I/C was administered intraperitoneally (i.p.) on day 0 and 500 ng TCDD/kg bodyweight on day 1. On day 4, CB3 infection had induced MT approximately 10-fold, regardless of TCDD treatment (P < 0.01 in infected mice and P < 0.001 in infected, TCDD-treated mice). TCDD alone induced a 10-fold increase in CYP1A1 activity (P < 0.001), whereas infection alone suppressed the normal CYP1A1 activity by 75% (P < 0.001). Infection also suppressed the TCDD-induced CYP1A1 activity by approximately 30% (n.s.). Poly I/C suppressed CYP1A1 by 20-25% (n.s.) at both basal and TCDD-induced levels. Serum IFN-alpha and IFN-beta levels were undetectable in controls, in TCDD-treated and in the poly I/C-treated groups on day 4, probably because the short IFN peak is detectable only hours after injection. Conversely, on day 4 of the infection, IFN-alpha and IFN-beta were consistently raised in the TCDD-treated infected mice, whereas increased IFNs as a result of infection alone could be detected in only one individual. These results suggest that the normal host responses during acute infections down-regulate detoxifying processes in favour of acute-phase protein synthesis. This may explain the observed changed pattern of accumulation, excretion and toxicity of the environmental pollutants cadmium and TCDD during this common virus infection.
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| 19. |
- Holmström, Henning, et al.
(författare)
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Geochemical investigations of sulfide-bearing tailings at Kristineberg, northern Sweden, a few years after remediation
- 2001
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 273:1-3, s. 111-113
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Tidskriftsartikel (refereegranskat)abstract
- In the Kristineberg mining area in northern Sweden, massive, pyrite-rich Zn-Cu ores are intercalated in ca. 1.9 Ga volcano-sedimentary rocks. Investigations of a tailings impoundment remediated by means of both till coverage and raising the groundwater table have been undertaken. The aim of the study was to characterise the tailings with respect to mineralogy, the chemical composition of both the tailings and the pore water, and to try to identify the significant reactions that may have occurred before and after remediation. It was found that the oxidation front had reached down to depths of between approximately 0.1 and 1.15 m before remediation. The oxidation of sulfides has produced high concentrations of some metals in the pore water; up to 26, 16, 4.1, 2.7 and 82 mg/l have been measured for Al, Mn, Fe and Zn, respectively. Concentrations of metals such as Cd, Co, Cu, Ni and Pb are lower, with average concentrations of 18.4, 83.8, 45, 79.6 and 451 μg/l, respectively. Higher concentrations of major elements such as Ca, Fe, Mn, Mg and S have been measured at depth in pore water than at shallower levels. This is probably caused by flush out of elements after remediation and vertical transport from the upper parts before remediation. The pH is relatively high, approximately 5.5 at most depths in the tailings, except in and around the former oxidation zone where it is lower, and where the highest dissolved concentrations of elements such as As, Cd, Co, Cu, Pb and Zn occur. This is probably due to the release of metals secondarily retained below the oxidation front prior to the remediation. Since the groundwater table is raised, the groundwater reaches the retained metals, which leads to desorption of metals and dissolution of secondary minerals.
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| 20. |
- Holmström, Henning, et al.
(författare)
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The character of the suspended and dissolved phases in the water cover of the flooded mine tailings at Stekenjokk, northern Sweden
- 2000
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 247:1, s. 15-31
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Tidskriftsartikel (refereegranskat)abstract
- Studies of the suspended and dissolved phases of the pond water, material collected from sediment traps, and surficial sediments/tailings from the flooded tailings pond at Stekenjokk have been performed. The aim was to characterise the material, to study the seasonal variations and to quantify possible resuspension of the tailings in the pond. The element concentrations in the pond at Stekenjokk seem to be largely controlled by processes controlling the precipitation and dissolution of Mn- and Fe-oxyhydroxides in both the water column and in the surficial tailings. Physiochemical processes such as weathering of silicates on the surrounding mountain slopes or dykes contributes both dissolved elements and detrital particles. The suspended phase consists of detrital silicate material as well as Fe- and Mn-oxyhydroxides. The average heavy metal concentrations are high, e.g. 0.42% Cu, 0.15% Pb and 3.1% Zn, which is probably due to sorption onto Fe- and Mn-oxyhydroxides. The suspended phase is richer in Fe, and particularly Mn, during the winter. The suspended phase resembles the material collected in sediment traps and the material in the surficial sediments. The pond water is well mixed during the ice-free season. The dissolved heavy metal concentrations are generally rather low with, e.g. maximum concentrations of 2.03 μg/l Cu, 0.23 μg/l Pb and 268 μg/l Zn during the winter. Higher dissolved concentrations are found below the ice-cover above the sediment surface during the winter, caused by diffusion of elements from the sediment-water interface up into the pond water. Most of the metals occurring in the pond are dissolved and resuspension of tailings is negligible.
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