| 1. |
- Lichtenberg, Elinor M., et al.
(författare)
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A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes
- 2017
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 23:11, s. 4946-4957
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural intensification is a leading cause of global biodiversity loss, which can reduce the provisioning of ecosystem services in managed ecosystems. Organic farming and plant diversification are farm management schemes that may mitigate potential ecological harm by increasing species richness and boosting related ecosystem services to agroecosystems. What remains unclear is the extent to which farm management schemes affect biodiversity components other than species richness, and whether impacts differ across spatial scales and landscape contexts. Using a global metadataset, we quantified the effects of organic farming and plant diversification on abundance, local diversity (communities within fields), and regional diversity (communities across fields) of arthropod pollinators, predators, herbivores, and detritivores. Both organic farming and higher in-field plant diversity enhanced arthropod abundance, particularly for rare taxa. This resulted in increased richness but decreased evenness. While these responses were stronger at local relative to regional scales, richness and abundance increased at both scales, and richness on farms embedded in complex relative to simple landscapes. Overall, both organic farming and in-field plant diversification exerted the strongest effects on pollinators and predators, suggesting these management schemes can facilitate ecosystem service providers without augmenting herbivore (pest) populations. Our results suggest that organic farming and plant diversification promote diverse arthropod metacommunities that may provide temporal and spatial stability of ecosystem service provisioning. Conserving diverse plant and arthropod communities in farming systems therefore requires sustainable practices that operate both within fields and across landscapes.
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| 2. |
- Vicedo-Cabrera, A.M., et al.
(författare)
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The burden of heat-related mortality attributable to recent human-induced climate change
- 2021
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Ingår i: Nature Climate Change. - : Nature Publishing Group. - 1758-678X .- 1758-6798. ; 11:6, s. 492-500
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Tidskriftsartikel (refereegranskat)abstract
- Climate change affects human health; however, there have been no large-scale, systematic efforts to quantify the heat-related human health impacts that have already occurred due to climate change. Here, we use empirical data from 732 locations in 43 countries to estimate the mortality burdens associated with the additional heat exposure that has resulted from recent human-induced warming, during the period 1991–2018. Across all study countries, we find that 37.0% (range 20.5–76.3%) of warm-season heat-related deaths can be attributed to anthropogenic climate change and that increased mortality is evident on every continent. Burdens varied geographically but were of the order of dozens to hundreds of deaths per year in many locations. Our findings support the urgent need for more ambitious mitigation and adaptation strategies to minimize the public health impacts of climate change.
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| 3. |
- Yu, Changxun, et al.
(författare)
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Iron behavior in a northern estuary: Large pools of non-sulfidized Fe(II) associated with organic matter
- 2015
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Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 413, s. 73-85
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Tidskriftsartikel (refereegranskat)abstract
- The estuaries of the Northern Baltic Sea (Gulf of Bothnia) receive an abundance of diagenetically reactive catchment-derived Fe, which is to a large degree complexed with organicmatter or present as Fe (hydr-) oxides. However, our understanding of sedimentary Fe diagenesis in these estuaries is limited. To address this limitation, the present study examines Fe geochemistry in a 3.5-m-thick estuarine benthic mud layer and three samples of suspended particulate matter of a catchment on the eastern Gulf of Bothnia. The age-depth model of the mud, constructed on the basis of sedimentary features as well as Cs-137 and aquatic plant C-14 determinations, revealed a high average rate of sedimentation (5 cm . yr(-1)) for the upper mud unit (0-182.5 cm, corresponding to 1973-2011), in response to intensive land-use (ditching) in the catchment since the 1960s and 1970s. The intensive land-use has resulted in a strong increase in the Fe accumulation rates, but has not caused a recognizable impact on the diagenetic processes of Fe including features such as degree of sulfidization and solid-phase partitioning. Iron X-ray absorption spectroscopy (XAS) indicated that in the suspended particulate matter, large proportions (47-58%) of Fe occur as Fe(III)-organic complexes and 2-line ferrihydrite. In the mud, the former is completely reduced, and reactive Fe (defined via extraction with 1 MHCl) was high throughout (52-68%, median = 61%) and strongly dominated by Fe(II). This reactive Fe(II) pool was sulfidized to only a limited extent (degree of reactive sulfidization = 11-26%, median = 17%). This phenomenon is attributed to the brackish-water conditions (i.e. low in sulfate) and the abundant input of reactive Fe(III) from the catchment, leading to a surplus of dissolved Fe2+ over dissolved sulfide in the sediment. The low availability of dissolved sulfide, in combination with the high average sedimentation rate, limits the formation of intermediate reduced sulfur compounds at the water-sediment interface, thereby retarding the conversion of FeS into pyrite (ratios of pyrite-S to AVS = 0.17-1.73, median = 0.37; degree of pyritization = 1-17%, median = 3%). Iron XAS, in combination with wavelet transform analysis, of representative sediment segments from the upper and lower mud units suggests that the non-sulfidized Fe(II) pool is dominantly complexed by organic matter, with the remaining Fe(II) occurring as mackinawite. This has implications for the understanding of early Fe diagenesis in settings with a high input of organic matter and relatively low supply of sulfate. (C) 2015 Elsevier B.V. All rights reserved.
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| 4. |
- Yu, Changxun, et al.
(författare)
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Manganese accumulation and solid-phase speciation in a 3.5 m thick mud sequence from the estuary of an acidic and Mn-rich creek, northern Baltic Sea
- 2016
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Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 437, s. 56-66
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Tidskriftsartikel (refereegranskat)abstract
- In sediments, manganese (Mn) is typically enriched in the form of authigenic Mn hydroxides at the water-sediment interface where intensive redox cycling of Mn occurs. Here we show, based on existing hydrochemical and geochemical (sediment core) data and new detailed chemical and mineralogical characterization of a 3.5 m long sediment core from a Boreal estuary, that the behavior of Mn can be profoundly different and more complex in estuarine settings receiving an abundance of terrestrial Mn. The most notable feature in the 3.5 m long sediment core is two depth intervals (60-155 cm and 181-230 cm) where there are strong fine-scale variations in Mn concentrations with peaks episodically reaching up to 10-25 g kg(-1) and 6.7-12 g kg(-1), respectively. X-ray absorption spectroscopy and sequential chemical extraction show that Mn occurs mainly as authigenic rhodochrosite at these two depth intervals and is mainly surface-sorbed in other sections with relatively low and stable Mn concentrations. The data suggests that the strong fine-scale variations in Mn concentrations are a reflection of the extent of formation and settling of Mn hydroxides, the precursors of the authigenic rhodochrosite (and also of the surface-sorbed Mn), rather than Mn input to the estuary or redox-related Mn translocation within the sediment. There was agreement between the results of linear combination fitting of extended X-ray absorption fine structure data and a 7-step sequential chemical extraction (SCE) in terms of quantification of surface-sorbed Mn species, whereas the SCE experiment failed to fractionate a majority of rhodochrosite into SCE step-2 (1M NH4-acetate at pH 6), which is frequently employed to dissolve carbonate. We ascribe this discrepancy to only partial dissolution of rhodochrosite in the weakly acidic (pH = 6) NH4-acetate leach.
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| 5. |
- Åström, E., et al.
(författare)
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Precision measurements of linear scattering density using muon tomography
- 2016
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Ingår i: Journal of Instrumentation. - : Institute of Physics Publishing. - 1748-0221. ; 11:7
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.
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| 6. |
- Åström, Mats E., 1963-, et al.
(författare)
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Extensive accumulation of rare earth elements in estuarine sediments affected by leaching of acid sulfate soils
- 2020
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Ingår i: Boreal Environment Research. - : Finnish Environmental Inst. - 1239-6095 .- 1797-2469. ; 25, s. 105-120
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Tidskriftsartikel (refereegranskat)abstract
- The concentrations, loads and speciation of rare earth elements (REEs) were studied in a 3.5 m thick mud depositional succession from an estuary in the Gulf of Bothnia. The uppermost 182.5 cm of the mud, estimated to have deposited from the early 1970s to 2011 (sampling year), had very high REE concentrations (596-1456 ppm) and accumulation rates (5.2-28 g m(-2) year(-1)). This was explained by large REE export from acid sulfate soils after they became efficiently drained with modern drainage techniques. Geochemical and synchrotron-based spectroscopic (XANES) analyses showed that the REEs in the mud are relatively firmly bound in non-clastic phases, likely adsorbed by clay minerals and also to some extent by iron oxyhydroxides. Below 182.5 cm, the REE concentrations successively decreased down to background values at the base at 3.5 m, reflecting less efficient drainage and leaching of the acid sulfate soils in previous decades and centuries.
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| 7. |
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| 8. |
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| 9. |
- Drake, Henrik, et al.
(författare)
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Variability of sulphur isotope ratios in pyrite and dissolved sulphate in granitoid fractures down to 1km depth - Evidence for widespread activity of sulphur reducing bacteria
- 2013
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 102, s. 143-161
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Tidskriftsartikel (refereegranskat)abstract
- Euhedral pyrite crystals in 46 open bedrock (granitoid) fractures at depths down to nearly 1 km were analysed for sulphur isotope ratios (delta S-34) by the in situ secondary ion mass spectrometry (SIMS) technique and by conventional bulk-grain analysis, and were compared with groundwater data. Twenty nine of the fractures sampled for pyrite had corresponding data for groundwater, including chemistry and isotopic ratios of sulphate, which provided a unique opportunity to compare the sulphur-isotopic ratios of pyrite and dissolved sulphate both at site and fracture-specific scales. Assessment of pyrite age and formation conditions were based on the geological evolution of the area (Laxemar, SE Sweden), and on data on co-genetic calcite as follows: (1) the isotopic ratios of the calcite crystals (delta O-18, delta C-13, Sr-87/Sr-86) were compared with previously defined isotopic features of fracture mineral assemblages precipitated during various geological periods, and (2) the delta O-18 of the calcites were compared with the delta O-18 of groundwater in fractures corresponding to those where the calcite/pyrite assemblages were sampled. Taken together, the data show that all the sampled fractures carried pyrite/calcite that are low-temperature and precipitated from the current groundwater or similar pre-existing groundwater, except at depths of -300 to -600 m where water with a glacial component dominates and the crystals are from pre-modern fluids. An age of <10 Ma are anticipated for the pre-modern fluids. The delta S-34(pyr) showed huge variations across individual crystals (such as -32 to +73 parts per thousand) and extreme minimum (-50 parts per thousand) and maximum (+91 parts per thousand) values. For this kind of extreme S-isotopic variation at earth-surface conditions there is no other explanation than activity of sulphur reducing bacteria coupled with sulphate-limited conditions. Indeed, the most common subgrain feature was an increase in delta S-34(pyr) values from interior to rim of the crystal, which we interpret are related to successively higher delta S-34 values of the dissolved source SO42- caused by ongoing bacterial sulphate reduction in fractures with low-flow or stagnant waters. The measured groundwater had delta S-34(SO4) values of +9 parts per thousand to +37 parts per thousand, with the highest values associated with low sulphate concentrations. These values are overall, and especially in the sulphate-poor waters down to -400 m, somewhat higher than the anticipated initial values, and can thus, like for the S-34-enriched pyrites, be explained by a Rayleigh distillation process driven by microbial sulphate reduction. An intriguing feature was that the delta S-34(SO4) values of the groundwater were in no case reaching up to the values required to produce biogenic pyrite with delta S-34 values of +40 parts per thousand to +91 parts per thousand. To explain this feature, we suggest that groundwater in low-flow fractures with near-stagnant water (carrying sulphate and pyrite with high delta S-34) is masked by high-flow parts of the fracture system carrying groundwater that often contains sulphate in abundance and considerably less fractionated with respect to S-34 and S-32. In order to gain detailed knowledge of chemical processes and patterns in groundwater in fractured rock, fracture-mineral investigations are a powerful tool, as we have shown here for the sulphur system. (C) 2012 Elsevier Ltd. All rights reserved.
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| 10. |
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| 11. |
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| 12. |
- Mathurin, Frédéric A., et al.
(författare)
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Effect of tunnel excavation on source and mixing of groundwater in a coastal granitoidic fracture network.
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:23, s. 12779-12786
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess how the excavation of the Äspö Hard Rock Laboratory tunnel has impacted on sources and mixing of groundwater in fractured crystalline (granitoidic) bedrock. The tunnel is 3600 m long and extends to a depth of 460 m at a coastal site in Boreal Europe. The study builds on a unique data set consisting of 1117 observations on chloride and δ(18)O of groundwater collected from a total of 356 packed-off fractures between 1987 and 2011. On the basis of the values of these two variables in selected source waters, a classification system was developed to relate the groundwater observations to source and postinfiltration mixing phenomena. The results show that the groundwater has multiple sources and a complex history of transport and mixing, and is composed of at least glacial water, marine water, recent meteoric water, and an old saline water. The tunnel excavation has had a large impact on flow, sources, and mixing of the groundwater. Important phenomena include upflow of deep-lying saline water, extensive intrusion of current Baltic Sea water, and substantial temporal variability of chloride and δ(18)O in many fractures.
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| 13. |
- Mathurin, Frédéric A., et al.
(författare)
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High cesium concentrations in groundwater in the upper 1.2km of fractured crystalline rock - Influence of groundwater origin and secondary minerals
- 2014
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier Ltd. - 0016-7037 .- 1872-9533. ; 132, s. 187-213
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Tidskriftsartikel (refereegranskat)abstract
- Dissolved and solid phase cesium (Cs) was studied in the upper 1.2km of a coastal granitoid fracture network on the Baltic Shield (Äspö Hard Rock Laboratory and Laxemar area, SE Sweden). There unusually high Cs concentrations (up to 5-6μgL-1) occur in the low-temperature (<20°C) groundwater. The material includes water collected in earlier hydrochemical monitoring programs and secondary precipitates (fracture coatings) collected on the fracture walls, as follows: (a) hydraulically pristine fracture groundwater sampled through 23 surface boreholes equipped for the retrieval of representative groundwater at controlled depths (Laxemar area), (b) fracture groundwater affected by artificial drainage collected through 80 boreholes drilled mostly along the Äspö Hard Rock Laboratory (underground research facility), (c) surface water collected in local streams, a lake and sea bay, and shallow groundwater collected in 8 regolith boreholes, and (d) 84 new specimens of fracture coatings sampled in cores from the Äspö HRL and Laxemar areas. The groundwater in each area is different, which affects Cs concentrations. The highest Cs concentrations occurred in deep-seated saline groundwater (median Äspö HRL: 4.1μgL-1; median Laxemar: 3.7μgL-1) and groundwater with marine origin (Äspö HRL: 4.2μgL-1). Overall lower, but variable, Cs concentrations were found in other types of groundwater. The similar concentrations of Cs in the saline groundwater, which had a residence time in the order of millions of years, and in the marine groundwater, which had residence times in the order of years, shows that duration of water-rock interactions is not the single and primary control of dissolved Cs in these systems. The high Cs concentrations in the saline groundwater is ascribed to long-term weathering of minerals, primarily Cs-enriched fracture coatings dominated by illite and mixed-layer clays and possibly wall rock micaceous minerals. The high Cs concentrations in the groundwater of marine origin are, in contrast, explained by relatively fast cation exchange reactions. As indicated by the field data and predicted by 1D solute transport modeling, alkali cations with low-energy hydration carried by intruding marine water are capable of (NH4 + in particular and K+ to some extent) replacing Cs+ on frayed edge (FES) sites on illite in the fracture coatings. The result is a rapid and persistent (at least in the order of decades) buildup of dissolved Cs concentrations in fractures where marine water flows downward. The identification of high Cs concentrations in young groundwater of marine origin and the predicted capacity of NH4 + to displace Cs from fracture solids are of particular relevance in the disposal of radioactive nuclear waste deep underground in crystalline rock. © 2014 Elsevier Ltd.
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| 14. |
- Mathurin, Frédéric A., et al.
(författare)
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REE and Y in groundwater in the upper 1.2 km of Proterozoic granitoids (Eastern Sweden) - Assessing the role of composition and origin of groundwaters, geochemistry of fractures, and organic/inorganic aqueous complexation
- 2014
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 144, s. 342-378
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Tidskriftsartikel (refereegranskat)abstract
- Yttrium and rare earth elements (YREEs) are studied in groundwater in the shallow regolith aquifer and the fracture networks of the upper 1.2 km of Paleoproterozoic granitoids in boreal Europe (Laxemar and Forsmark areas, Sweden). The study includes groundwater sampled via a total of 34 shallow boreholes reaching the bottom of the regolith aquifer, and 72 deep boreholes with equipment designed for retrieval of representative groundwater at controlled depths in the fractured bedrock. The groundwater composition differs substantially between regolith and fracture groundwater and between areas, which affects the dissolved YREE features, including concentrations and NASC normalized patterns. In the fresh groundwater in the regolith aquifers, highest YREE concentrations occur (10th and 90th percentile; Laxemar: 4.4-82 mu g L-1; Forsmark: 1.9-19 mu g L-1), especially in the slightly acidic groundwater (pH: 6.3-7.2 - Laxemar), where the normalized YREE patterns are slightly enriched in light REEs (La-NASC/Y-NASC: 1.1-2.4). In the recharge areas, where redox potentials of the regolith groundwater is more moderate, negative Ce anomaly (Laxemar: 0.37-0.45; Forsmark: 0.15-0.92) and positive Y anomaly (mainly in Forsmark: 1.0-1.7) are systematically more pronounced than in discharge areas. The significant correlations between the YREE features and dissolved organic carbon, minor elements, and somewhat pH suggest a strong control of humic substances (HSs) together with Al rich colloids and redox sensitive Fe-Mn hydrous precipitates on the dissolved YREE pools. In the bedrock fractures, the groundwater is circumneutral to slightly basic and displays YREE concentrations that are at least one order of magnitude lower than the regolith groundwater, and commonly below detection limit in the deep brackish and saline groundwater, with some exceptions such as La and Y. At intermediate depth (>50 m), where groundwater of meteoric origin percolates, the La-NASC/Y-NASC values moderately to substantially decrease (Laxemar: 0.24-2.65; Forsmark: 0.02-0.06) and Y and Ce anomalies are negligible as compared to the regolith groundwater. Aqueous speciation modeling predicts substantial binding of dissolved Y and La, respectively, to HSs. This, in turn, suggests that the features of the YREE pool in the meteoric fracture groundwater are dominantly controlled by the capacity of fracture minerals to sorb HS ligands inherited from the overlying terrestrial regolith. In the deep bedrock fractures (>100/200 m), the YREE features vary substantially with the groundwater paleo-origin. In Laxemar, where groundwater with pronounced glacial origin percolates, the YREE concentrations decrease with increasing mixing fraction of glacial melt water. There, the dissolved YREEs are mostly bound to HSs, and inherited their fractionation features (La-NASC/Y-NASC: 0.15-2.1) from water-rock interaction in the intermediate bedrock fractures. In Forsmark, the YREE and heavy REE enrichment (La-NASC/Y-NASC: 0.007-0.23) are more systematic in the groundwater with pronounced marine origin, due to water-mineral interactions in the sea sediment and in the fractures while infiltrating and percolating. YREE features significantly change in the deep saline groundwater with a long residence time, which displays La-NASC/Y-NASC similar to those of the local bedrock. The findings of this study are relevant in terms of safety assessment for nuclear waste disposal in crystalline rock carrying groundwater influenced by various paleo-climatic recharges. (C) 2014 Elsevier Ltd. All rights reserved.
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| 15. |
- Nelson, A E, et al.
(författare)
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Diagnosis of a patient with oncogenic osteomalacia using a phosphate uptake bioassay of serum and magnetic resonance imaging
- 2001
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Ingår i: European Journal of Endocrinology. - : Oxford University Press (OUP). - 0804-4643 .- 1479-683X. ; 145:4, s. 469-476
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Tidskriftsartikel (refereegranskat)abstract
- A previously healthy man with no family history of fractures presented with muscle pain, back pain and height loss. Investigations revealed hypophosphataemia, phosphaturia, undetectable serum 1,25-dihydroxyvitamin D and severe osteomalacia on bone biopsy, suggestive of a diagnosis of oncogenic osteomalacia. Thorough physical examination did not locate a tumour. Support for the diagnosis was obtained by detection of phosphate uptake inhibitory activity in a blinded sample of the patient's serum using a renal cell bioassay. On the basis of detection of this bioactivity, a total body magnetic resonance (MR) examination was performed. A small tumour was located in the right leg. Removal of the tumour resulted in the rapid reversal of symptoms and the abnormal biochemistry typical of oncogenic osteomalacia. Inhibitory activity was also demonstrated using the bioassay in serum from two other patients with confirmed or presumptive oncogenic osteomalacia, but not in serum from two patients with hypophosphataemia of other origin. This is the first case to be reported in which the diagnosis of oncogenic osteomalacia was assisted by demonstration of inhibitory activity of the patient's serum in a renal cell phosphate bioassay that provided an impetus for total body MR imaging.
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| 16. |
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| 17. |
- Reischer, G. H., et al.
(författare)
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Performance Characteristics of qPCR Assays Targeting Human- and Ruminant-Associated Bacteroidetes for Microbial Source Tracking across Sixteen Countries on Six Continents
- 2013
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:15, s. 8548-8556
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Tidskriftsartikel (refereegranskat)abstract
- Numerous quantitative PCR assays for microbial fecal source tracking (MST) have been developed and evaluated in recent years. Widespread application has been hindered by a lack of knowledge regarding the geographical stability and hence applicability of such methods beyond the regional level. This study assessed the performance of five previously reported quantitative PCR assays targeting human-, cattle-, or ruminant-associated Bacteroidetes populations on 280 human and animal fecal samples from 16 countries across six continents. The tested cattle-associated markers were shown to be ruminant-associated. The quantitative distributions of marker concentrations in target and nontarget samples proved to be essential for the assessment of assay performance and were used to establish a new metric for quantitative source-specificity. In general, this study demonstrates that stable target populations required for marker-based MST occur around the globe. Ruminant-associated marker concentrations were strongly correlated with total intestinal Bacteroidetes populations and with each other, indicating that the detected ruminant-associated populations seem to be part of the intestinal core microbiome of ruminants worldwide. Consequently tested ruminant-targeted assays appear to be suitable quantitative MST tools beyond the regional level while the targeted human-associated populations seem to be less prevalent and stable, suggesting potential for improvements in human-targeted methods.
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| 18. |
- Stafoggia, M., et al.
(författare)
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Joint effect of heat and air pollution on mortality in 620 cities of 36 countries
- 2023
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 181
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Tidskriftsartikel (refereegranskat)abstract
- Background: The epidemiological evidence on the interaction between heat and ambient air pollution on mor-tality is still inconsistent. Objectives: To investigate the interaction between heat and ambient air pollution on daily mortality in a large dataset of 620 cities from 36 countries. Methods: We used daily data on all-cause mortality, air temperature, particulate matter <= 10 mu m (PM10), PM <= 2.5 mu m (PM2.5), nitrogen dioxide (NO2), and ozone (O3) from 620 cities in 36 countries in the period 1995-2020. We restricted the analysis to the six consecutive warmest months in each city. City-specific data were analysed with over-dispersed Poisson regression models, followed by a multilevel random-effects meta-analysis. The joint association between air temperature and air pollutants was modelled with product terms between non-linear functions for air temperature and linear functions for air pollutants. Results: We analyzed 22,630,598 deaths. An increase in mean temperature from the 75th to the 99th percentile of city-specific distributions was associated with an average 8.9 % (95 % confidence interval: 7.1 %, 10.7 %) mortality increment, ranging between 5.3 % (3.8 %, 6.9 %) and 12.8 % (8.7 %, 17.0 %), when daily PM10 was equal to 10 or 90 mu g/m3, respectively. Corresponding estimates when daily O3 concentrations were 40 or 160 mu g/ m3 were 2.9 % (1.1 %, 4.7 %) and 12.5 % (6.9 %, 18.5 %), respectively. Similarly, a 10 mu g/m3 increment in PM10 was associated with a 0.54 % (0.10 %, 0.98 %) and 1.21 % (0.69 %, 1.72 %) increase in mortality when daily air temperature was set to the 1st and 99th city-specific percentiles, respectively. Corresponding mortality estimate for O3 across these temperature percentiles were 0.00 % (-0.44 %, 0.44 %) and 0.53 % (0.38 %, 0.68 %). Similar effect modification results, although slightly weaker, were found for PM2.5 and NO2. Conclusions: Suggestive evidence of effect modification between air temperature and air pollutants on mortality during the warm period was found in a global dataset of 620 cities.
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| 19. |
- Tillberg, Mikael, et al.
(författare)
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Fractionation of Rare Earth Elements in Greisen and Hydrothermal Veins Related to A-Type Magmatism
- 2019
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Ingår i: Geofluids. - : Hindawi Limited. - 1468-8115 .- 1468-8123. ; 2019
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on concentrations and fractionation of rare earth elements (REE) in a variety of minerals and bulk materials of hydrothermal greisen and vein mineralization in Paleoproterozoic monzodiorite to granodiorite related to the intrusion of Mesoproterozoic alkali- and fluorine-rich granite. The greisen consists of coarse-grained quartz, muscovite, and fluorite, whereas the veins mainly contain quartz, calcite, epidote, chlorite, and fluorite in order of abundance. A temporal and thus genetic link between the granite and the greisen/veins is established via high spatial resolution in situ Rb-Sr dating, supported by several other isotopic signatures (delta S-34, Sr-87/Sr-86, delta O-18, and delta C-13). Fluid-inclusion microthermometry reveals that multiple pulses of moderately to highly saline aqueous to carbonic solutions caused greisenization and vein formation at temperatures above 200-250 degrees C and up to 430 degrees C at the early hydrothermal stage in the veins. Low calculated Sigma REE concentration for bulk vein (15ppm) compared to greisen (75ppm), country rocks (173-224ppm), and the intruding granite (320ppm) points to overall low REE levels in the hydrothermal fluids emanating from the granite. This is explained by efficient REE retention in the granite via incorporation in accessory phosphates, zircon, and fluorite and unfavorable conditions for REE partitioning in fluids at the magmatic and early hydrothermal stages. A noteworthy feature is substantial heavy REE (HREE) enrichment of calcite in the vein system, in contrast to the relatively flat patterns of greisen calcite. The REE fractionation of the vein calcite is explained mainly by fractional crystallization, where the initially precipitated epidote in the veins preferentially incorporates most of the light REE (LREE) pool, leaving a residual fluid enriched in the HREE from which calcite precipitated. Fluorite occurs throughout the system and displays decreasing REE concentrations from granite towards greisen and veins and different fractionation patterns among all these three materials. Taken together, these features confirm efficient REE retention in the early stages of the system and minor control of the REE uptake by mineral-specific partitioning. REE-fractionation patterns and fluid-inclusion data suggest that chloride complexation dominated REE transport during greisenization, whereas carbonate complexation contributed to the HREE enrichment in vein calcite.
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| 20. |
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| 21. |
- Yu, Changxun, et al.
(författare)
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Arsenic removal from contaminated brackish sea water by sorption onto Al hydroxides and Fe phases mobilized by land-use
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 542, s. 923-934
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Tidskriftsartikel (refereegranskat)abstract
- This study examines the spatial and temporal distribution patterns of arsenic (As) in solid and aqueous materials along the mixing zone of an estuary, located in the south-eastern part of the Bothnian Bay and fed by a creek running through an acid sulfate (AS) soil landscape. The concentrations of As in solution form (<1 kDa) increase steadily from the creek mouth to the outer estuary, suggesting that inflowing seawater, rather than AS soil, is the major As source in the estuary. In sediments at the outer estuary, As was accumulated and diagenetically cycled in the surficial layers, as throughout much of the Bothnian Bay. In contrast, in sediments in the inner estuary, As concentrations and accumulation rates showed systematical peaks at greater depths. These peaks were overall consistent with the temporal trend of past As discharges from the Ronnskar smelter and the accompanied As concentrations in past sea-water of the Bothnian Bay, pointing to a connection between the historical smelter activities and the sediment-bound As in the inner estuary. However, the concentrations and accumulation rates of As peaked at depths where the smelter activities had already declined, but a large increase in the deposition of Al hydroxides and Fe phases occurred in response to intensified land-use in the mid 1960's and early 1970's. This correspondence suggests that, apart from the inflowing As-contaminated seawater, capture by Al hydroxides, Fe hydroxides and Fe-organic complexes is another important factor for As deposition in the inner estuary. After accumulating in the sediment, the solid-phase As was partly remobilized, as reflected by increased pore-water As concentrations, a process favored by As(V) reduction and high concentrations of dissolved organic matter. (C) 2015 Elsevier B.V. All rights reserved.
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| 22. |
- Yu, Changxun, 1983-, et al.
(författare)
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Storage and Distribution of Organic Carbon and Nutrients in Acidic Soils Developed on Sulfidic Sediments : The Roles of Reactive Iron and Macropores
- 2024
-
Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 58:21, s. 9200-9212
-
Tidskriftsartikel (refereegranskat)abstract
- In a boreal acidic sulfate-rich subsoil (pH 3–4) developing on sulfidic and organic-rich sediments over the past 70 years, extensive brownish-to-yellowish layers have formed on macropores. Our data reveal that these layers (“macropore surfaces”) are strongly enriched in 1 M HCl-extractable reactive iron (2–7% dry weight), largely bound to schwertmannite and 2-line ferrihydrite. These reactive iron phases trap large pools of labile organic matter (OM) and HCl-extractable phosphorus, possibly derived from the cultivated layer. Within soil aggregates, the OM is of a different nature from that on the macropore surfaces but similar to that in the underlying sulfidic sediments (C-horizon). This provides evidence that the sedimentary OM in the bulk subsoil has been largely preserved without significant decomposition and/or fractionation, likely due to physiochemical stabilization by the reactive iron phases that also existed abundantly within the aggregates. These findings not only highlight the important yet underappreciated roles of iron oxyhydroxysulfates in OM/nutrient storage and distribution in acidic sulfate-rich and other similar environments but also suggest that boreal acidic sulfate-rich subsoils and other similar soil systems (existing widely on coastal plains worldwide and being increasingly formed in thawing permafrost) may act as global sinks for OM and nutrients in the short run.
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| 23. |
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| 24. |
- Åström, Mats E., 1963-, et al.
(författare)
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Sources, transport and sinks of beryllium in a coastal landscape affected by acidic soils
- 2018
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier. - 0016-7037 .- 1872-9533. ; 232, s. 288-302
-
Tidskriftsartikel (refereegranskat)abstract
- Beryllium (Be) sources, transport and sinks were studied in a coastal landscape where acidic soils (acid sulfate soils) have developed after drainage of fine-grained sulfide-bearing sediments. The study included the determination of total abundance and speciation of Be in a variety of solid and aqueous materials in both the terrestrial and estuarine parts of the landscape. A major feature was that despite normal (background) Be concentration in the sulfide-bearing sediments, the Be leaching from these sediments after O2-exposure and acid sulfate soil development were extensive, with concentrations up to 76 μg L−1 in soil water, 39 μg L−1 in runoff and 12 μg L−1 in low-order streams. These high Be concentrations were mainly in the solution form (i.e., passing a 1 kilodalton filter) and modelled to be dominated by free Be2+. The extensive Be release within, and leaching from the acid sulfate soils was controlled by pH, with a critical value of 4.0 below which the Be concentrations increased strongly. Although plagioclase and mica were most likely the main carriers of Be within these soils, it is suggested that other minerals such as Be hydroxides, Al hydroxides carrying Be, and Be sulfides are the main contributors of the abundance of dissolved Be in the acidic waters. When the acidic and Be-rich creek water was neutralized in the estuary of relatively low salinity, the dominating solution form of Be was removed by transformation to particles, reflected in the suspended particulate matter that had hydroxylamine hydrochloride extractable Be up to 17 mg kg−1 and ammonium acetate EDTA extractable Be up to 4 mg kg−1. In corresponding pristine materials (parent material of the acid sulfate soils) in the catchment, the median Be extractability with these reagents were only 0.3 and 0.05 mg kg−1, respectively. As the Be-rich suspended particulate matter ultimately became benthic sediment, the Be was preserved in terms of total concentrations but underwent to some extent changes in speciation, including release from hydroxides and concomitant scavenging by organic matter and particle surfaces.
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| 25. |
- Åström, S U, et al.
(författare)
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Genetic interactions between a null allele of the RIT1 gene encoding an initiator tRNA-specific modification enzyme and genes encoding translation factors in Saccharomyces cerevisiae
- 1999
-
Ingår i: Molecular General Genetics. - : Springer. - 0026-8925 .- 1432-1874. ; 261:6, s. 967-976
-
Tidskriftsartikel (refereegranskat)abstract
- The Saccharomyces cerevisiae gene RIT1 encodes a phospho-ribosyl transferase that exclusively modifies the initiator tRNA (tRNAMet(i)) by the addition of a 2'-O-ribosyl phosphate group to Adenosine 64. As a result, tRNAMet(i) is prevented from participating in the elongation steps of protein synthesis. We previously showed that the modification is not essential for the function of tRNAMet(i) in the initiation of translation, since rit1 null strains are viable and show no obvious growth defects. Here, we demonstrate that yeast strains in which a rit1 null allele is combined with mutations in any of the genes for the three subunits of eukaryotic initiation factor-2 (eIF-2), or with disruption alleles of two of the four initiator methionine tRNA (IMT) genes, show synergistic growth defects. A multicopy plasmid carrying an IMT gene can alleviate these defects. On the other hand, introduction of a high-copy-number plasmid carrying the TEF2 gene, which encodes the eukaryotic elongation factor 1alpha (eEF-1alpha), into rit1 null strains with two intact IMT genes had the opposite effect, indicating that increased levels of eEF-1alpha are deleterious to these strains, presumably due to sequestration of the unmodified met-tRNAMet(i) for elongation. Thus, under conditions in which the components of the ternary met-tRNAMet(i):GTP:eIF-2 complex become limiting or are functionally impaired, the presence of the 2'-O-ribosyl phosphate modification in tRNAMet(i) is important for the provision of adequate amounts of tRNAMet(i) for formation of this ternary complex.
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| 26. |
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| 27. |
- Alakangas, Linda J., et al.
(författare)
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Diverse fractionation patterns of Rare Earth Elements in deep fracture groundwater in the Baltic Shield - Progress from utilisation of Diffusive Gradients in Thin-films (DGT) at the Aspo Hard Rock Laboratory
- 2020
-
Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier. - 0016-7037 .- 1872-9533. ; 269, s. 15-38
-
Tidskriftsartikel (refereegranskat)abstract
- Rare earth elements (REEs) were studied in groundwater in fractures at depths between 144 m and 450 m in Proterozoic granitoids on the Baltic Shield at a coastal site in south eastern Sweden (Aspo Hard Rock Laboratory). A specially designed device was used to sample the groundwater under in situ high pressure and low redox conditions. The REEs were measured via both diffusive gradients in thin-films (DGT) samplers after approximately three-week deployment times, and after conventional filtration (0.45 mu m membrane filters). The concentrations of REEDGT were lower than the REE0.45 mu m concentrations in all 14 studied groundwaters. This is explained by development of a diffuse boundary layer (DBL) in the solution at the DGTs caused by the low flow, and in some of the groundwaters additionally by the presence of organically complexed REE that diffuse slowly in the diffusive gel of the DGT. Among the 14 studied groundwaters there was a huge range in REEDGT-fractionation patterns, ranging from enrichment to a nearly three-order-of-magnitude depletion of the heavy REEs (HREEs), despite a relatively homogenous bedrock (granitoids). The HREE enrichment is explained by preservation of the fractionation signature as HREE enriched sea water intruded and flowed through the fractures, supported by the high proportion of modelled REE fulvic-acid complexes in these waters. The strong HREE depletion, which occurred in saline groundwater, was ascribed to an advanced REE equilibrium between the groundwater and primary and/or secondary minerals and the pore water in the bedrock. Yet other groundwaters had flat or moderately HREE depleted patterns, which in some cases may have been caused by mixing of small portions of surficial waters with saline groundwater. (C) 2019 Elsevier Ltd. All rights reserved.
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| 28. |
- Alakangas, Linda J., et al.
(författare)
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Sampling and Characterizing Rare Earth Elements in Groundwater in Deep-Lying Fractures in Granitoids Under In Situ High-Pressure and Low-Redox Conditions
- 2014
-
Ingår i: Aquatic geochemistry. - : Springer Science and Business Media LLC. - 1380-6165 .- 1573-1421. ; 20:4, s. 405-418
-
Tidskriftsartikel (refereegranskat)abstract
- Several countries are preparing to dispose of radioactive nuclear waste deep underground in crystalline rock. This type of bedrock is commonly extensively fractured and consequently carries groundwater that serves as a medium for transporting metals and radionuclides. A group of metals of particular interest in this context is the rare earth elements (REEs), because they are analogues of actinides contained within radioactive waste and are tracers of hydrological pathways and geochemical processes. Concentrations of REEs are commonly low in these groundwaters, leading to values below detection limits of standard monitoring methods, particularly for the heavy REEs. We present a new technical set-up for monitoring REEs (and other trace metals) in groundwater in fractured crystalline rock. The technique consists of passing the fracture groundwater, commonly under high pressure and containing reduced chemical species, through a device that maintains the physicochemical character of the groundwater. Within the device, diffusive gradient in thin-film (DGT) discs are installed in triplicate. With this set-up, we studied REEs in groundwater in fractures at depths of approximately -144, -280, and -450 m in granitoids in the A"spo Hard Rock Laboratory in southern Sweden. The entire REE suite was detected (concentrations down to 0.1 ng L-1) and was differently fractionated among the groundwaters. The shallowest groundwater, composed of dilute modern Baltic Sea water, was enriched in the heavy REEs, whereas the deeper groundwaters, dominated by old saline water, were depleted in the heavy REEs. Deployment periods varying from 1 to 4 weeks delivered similar REE concentrations, indicating stability and reproducibility of the experimental set-up. The study finds that 1 week of deployment may be enough. However, if the overall setting and construction allow for longer deployment times, 2-3 weeks will be optimal in terms of reaching reliable REE concentrations well above the detection limit while maintaining the performance of the DGT samplers.
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| 29. |
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| 30. |
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| 31. |
- Augustsson, Anna, et al.
(författare)
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Failure of generic risk assessment model framework to predict groundwater pollution risk at hundreds of metal contaminated sites : Implications for research needs
- 2020
-
Ingår i: Environmental Research. - : Elsevier. - 0013-9351 .- 1096-0953. ; 185, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- Soil pollution constitutes one of the major threats to public health, where spreading to groundwater is one of several critical aspects. In most internationally adopted frameworks for routine risk assessments of contaminated land, generic models and soil guideline values are cornerstones. In order to protect the groundwater at contaminated sites, a common practice worldwide today is to depart from health risk-based limit concentrations for groundwater, and use generic soil-to-groundwater spreading models to back-calculate corresponding equilibrium levels (concentration limits) in soil, which must not be exceeded at the site. This study presents an extensive survey of how actual soil and groundwater concentrations, compiled for all high-priority contaminated sites in Sweden, relate to the national model for risk management of contaminated sites, with focus on As, Cu, Pb and Zn. Results show that soil metal concentrations, as well as total amounts, constitute a poor basis for assessing groundwater contamination status. The evaluated model was essentially incapable of predicting groundwater contamination (i.e. concentrations above limit values) based on soil data, and erred on the "unsafe side" in a significant number of cases, with modelled correlations not being conservative enough. Further, the risk of groundwater contamination was almost entirely independent of industry type. In essence, since neither soil contaminant loads nor industry type is conclusive, there is a need for a supportive framework for assessing metal spreading to groundwater accounting for site-specific, geochemical conditions.
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| 32. |
- Augustsson, Anna, et al.
(författare)
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High metal reactivity and environmental risks at a site contaminated by glass waste
- 2016
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 154, s. 434-443
-
Tidskriftsartikel (refereegranskat)abstract
- This study addresses the reactivity and risks of metals (Ba, Cd, Co, Cr, Cu, Ni, Pb, Zn, As and Sb) at a Swedish site with large glass waste deposits. Old glassworks sites typically have high total metal concentrations, but as the metals are mainly bound within the glass waste and considered relatively inert, environmental investigations at these kinds of sites are limited. In this study, soil and landfill samples were subjected to a sequential chemical extraction procedure. Data from batch leaching tests and groundwater upstream and downstream of the waste deposits were also interpreted. The sequential extraction revealed that metals in <2 mm soil/waste samples were largely associated with geochemically active fractions, indicating that metals are released from pristine glass and subsequently largely retained in the surrounding soil and/or on secondary mineral coatings on fine glass particles. From the approximately 12,000 m(3) of coarse glass waste at the site, almost 4000 kg of Pb is estimated to have been lost through corrosion, which, however, corresponds to only a small portion of the total amount of Pb in the waste. Metal sorption within the waste deposits or in underlying soil layers is supported by fairly low metal concentrations in groundwater. However, elevated concentrations in downstream groundwater and in leachates of batch leaching tests were observed for several metals, indicating on-going leaching. Taken together, the high metal concentrations in geochemically active forms and the high amounts of as yet uncorroded metal-rich glass, indicate considerable risks to human health and the environment.
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| 33. |
- Augustsson, Anna, et al.
(författare)
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The risk of overestimating the risk-metal leaching to groundwater near contaminated glass waste deposits and exposure via drinking water
- 2016
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 566, s. 1420-1431
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates metal contamination patterns and exposure to Sb, As, Ba, Cd and Pb via intake of drinking water in a region in southeastern Sweden where the production of artistic glass has resulted in a large number of contaminated sites. Despite high total concentrations of metals in soil and groundwater at the glassworks sites properties, all drinking water samples from households with private wells, located at a 30-640 m distance from a glassworks site, were below drinking water criteria from the WHO for Sb, As, Ba and Cd. A few drinking water samples showed concentrations of Pb above the WHO guideline, but As was the only element found in concentrations that could result in human exposure near toxicological reference values. An efficient retention of metals in the natural soil close to the source areas, which results in a moderate impact on local drinking water, is implied. Firstly, by the lack of significant difference in metal concentrations when comparing households located upstream and downstream of the main waste deposits, and secondly, by the lack of correlation between the metal concentration in drinking water and distance to the nearest glassworks site. However, elevated Pb and Cd concentrations in drinking water around glassworks sites when compared to regional groundwater indicate that diffuse contamination of the soils found outside the glassworks properties, and not only the glass waste landfills, may have a significant impact on groundwater quality. We further demonstrate that different mobilization patterns apply to different metals. Regarding the need to use reliable data to assess drinking water contamination and human exposure, we finally show that the conservative modelling approaches that are frequently used in routine risk assessments may result in exposure estimates many times higher than those based on measured concentrations in the drinking water that is actually being used for consumption. (C) 2016 Elsevier B.V. All rights reserved.
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| 34. |
- Augustsson, Anna, et al.
(författare)
-
Trace metals in recharge and discharge ground waters at two sites at the Baltic coast of Sweden
- 2009
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Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 24:9, s. 1640-1652
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Tidskriftsartikel (refereegranskat)abstract
- The distribution and controls of trace elements (Cd, Cr, Cu, Ni, Pb, Zn and U) in shallow groundwater in discharge and recharge zones were analysed at two sites on the Baltic coast of Sweden; one granite-dominated and one with a significant addition of calcite. Although the study sites differ in overburden geochemistry and groundwater trace metal concentrations, which were well reflected in the general groundwater composition, the relative hydrochemical differences between recharge and discharge ground waters were similar at both sites, and temporally stable. The concentrations of Cd, Cu, Ni and U were higher in soil tubes in recharge areas, but Cr was higher in discharge zones. Also concentrations of HS, Fe, Mn and NH4 were higher in discharge samples, which in combination with increased 34S values provide strong evidence of a transition from oxidizing to more reducing conditions along the groundwater flow gradient. In terms of trace metals, this might mean either mobilisation due to dissolution of trace-metal carrying Fe(III) and Mn(IV) phases, or immobilisation caused by precipitation of discrete trace-metal sulfides or co-precipitation with Fe sulfides. The results from this study show that the latter is dominant in both the carbonate and granite environments for the metals Cd, Cu and Ni. Chromium concentrations were likely coupled to organic complexation and were higher in discharge groundwater, where DOC was also more abundant. As the concentration of several potentially toxic trace metals were found to differ between recharge and discharge areas, a climate driven change in hydrology might have a substantial impact on the distribution of these metals.
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| 35. |
- Barsoum, E., et al.
(författare)
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RAS/Cyclic AMP and Transcription Factor Msn2 Regulate Mating and Mating-Type Switching in the Yeast Kluyveromyces lactis
- 2011
-
Ingår i: Eukaryotic Cell. - 1535-9778 .- 1535-9786. ; 10:11, s. 1545-1552
-
Tidskriftsartikel (refereegranskat)abstract
- In response to harsh environmental conditions, ascomycetes produce stress-resistant spores to promote survival. As sporulation requires a diploid DNA content, species with a haploid lifestyle, such as Kluyveromyces lactis, first induce mating in response to stress. In K. lactis, mating and mating-type switching are induced by the DNA-binding protein Mts1. Mts1 expression is known to be upregulated by nutrient limitation, but the mechanism is unknown. We show that a ras2 mutation results in a hyperswitching phenotype. In contrast, strains lacking the phosphodiesterase Pde2 had lower switching rates compared to that of the wild type (WT). As Ras2 promotes cyclic AMP (cAMP) production and Pde2 degrades cAMP, these data suggest that low cAMP levels induce switching. Because the MTS1 regulatory region contains several Msn2 binding sites and Msn2 is a transcription factor that is activated by low cAMP levels, we investigated if Msn2 regulates MTS1 transcription. Consistently with this idea, an msn2 mutant strain displayed lower switching rates than the WT strain. The transcription of MTS1 is highly induced in the ras2 mutant strain. In contrast, an msn2 ras2 double mutant strain displays WT levels of the MTS1 transcript, showing that Msn2 is a critical inducer of MTS1 transcription. Strains lacking Msn2 and Pde2 also exhibit mating defects that can be complemented by the ectopic expression of Mts1. Finally, we show that MTS1 is subjected to negative autoregulation, presumably adding robustness to the mating and switching responses. We suggest a model in which Ras2/cAMP/Msn2 mediates the stress-induced mating and mating-type switching responses in K. lactis.
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| 36. |
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| 37. |
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| 38. |
- Berger, Tobias, et al.
(författare)
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Fluoride abundance and controls in fresh groundwater in Quaternary deposits and bedrock fractures in an area with fluorine-rich granitoid rocks
- 2016
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 569, s. 948-960
-
Tidskriftsartikel (refereegranskat)abstract
- This study focuses on fluoride (F-) concentrations in groundwater in an area in northern Europe (Laxemar, southeast Sweden) where high F- concentrations have previously been found in surface waters such as streams and quarries. Fluoride concentrations were determined over time in groundwater in the Quaternary deposits ("regolith groundwater"), and with different sampling techniques from just beneath the ground surface to nearly -700 min the bedrock (fracture) groundwater. A number of potential controls of dissolved F- were studied, including geological variables, mineralogy, mineral chemistry and hydrology. In the regolith groundwater the F- concentrations (0.3-4.2 mg/L) were relatively stable over time at each sampling site but varied widely among the sampling sites. In these groundwaters, the F- concentrations were uncorrelated with sample (filter) depth and the water table in meters above sea level (masl), with the thicknesses of the groundwater column and the regolith, and with the distribution of soil types at the sampling sites. Fluoride concentrations were, however, correlated with the anticipated spatial distribution of erosional material (till) derived from a F-rich circular granite intrusion. Abundant release of F-from such material is thus suggested, primarily via dissolution of fluorite and weathering of biotite. In the fresh fracture groundwater, the F- concentrations (1.2-7.4 mg/L) were generally higher than in the regolith groundwater, and were uncorrelated with depth and with location relative to the granite intrusion. Two mechanisms explaining the overall high F- levels in the fracture groundwater were addressed. First, weathering/dissolution of fluorite, bastnasite and apophyllite, which are secondary minerals formed in the fractures during past hydrothermal events, and biotite which is a primary mineral exposed on fracture walls. Second, long water-residence times, favoring water-rock interaction and build-up of high dissolved F- concentrations. The findings are relevant in contexts of extraction of groundwater for drinking-water purposes. (C) 2016 Elsevier B.V. All rights reserved.
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| 39. |
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| 40. |
- Berger, Tobias
(författare)
-
Fluoride in surface water and groundwater in southeast Sweden : sources, controls and risk aspects
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to determine the sources, controls and risk aspects of fluoride in surface water and groundwater in a region of southeastern Sweden where the fluorine-rich 1.45 Ga circular Götemar granite (5 km in diameter) crops out in the surrounding 1.8 Ga granites and quartz monzodiorites (TIB rocks). The materials of this thesis include both primary data, collected for the purpose of this thesis, and a large set of secondary data, retrieved from the Swedish Nuclear Fuel and Waste Management Co., the Swedish Geological Survey and the Kalmar County Council. A characteristic feature of the area is high fluoride concentrations in all kinds of natural waters, including surface waters (such as streams) and groundwater in both the Quaternary deposits (regolith groundwater) and bedrock fractures (fracture groundwater). A number of potential sources and controls of the high fluoride concentrations were investigated, including a variety of geological, mineralogical, mineral-chemical and hydrological features and processes. For the stream waters and regolith groundwater, high fluoride concentrations were correlated with the location of the Götemar granite. This finding is explained by the discharge of fluoride-rich groundwater from fractures in the bedrock and/or the release of fluoride due to the weathering of fluorine-bearing minerals in the Quaternary deposits; however, the Quaternary deposits had considerably lower fluoride concentrations than the underlying bedrock. The high fluoride concentrations in the fresh fracture groundwater (up to 7.4 mg/L) in the TIB-rocks are proposed to be the result of long residence times and the alteration/dissolution of fluorine-bearing primary and secondary minerals along the fracture walls. In terms of risk aspects, this thesis shows that fluoride can add to the transport and inorganic complexation of aluminium in humic-rich, acidic streams. Additionally, 24 % of the children in households with private wells in Kalmar County were assessed to be at risk of excess fluoride intake based on the WHO drinking water guideline value (1.5 mg/L). However, the risk increased significantly when instead the US EPA reference dose (0.06 mg/kg-day) was used, both when all relevant exposure pathways were taken into account as well as water consumption alone. Hence, it is shown that the risk of an excess intake of fluoride is strongly dependent on the basis for evaluation.
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| 41. |
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| 42. |
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| 43. |
- Berger, Tobias, et al.
(författare)
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Fluorine geochemistry of quaternary deposits in a nemo-boreal catchment with elevated dissolved fluoride in surface waters and groundwater
- 2016
-
Ingår i: Journal of Geochemical Exploration. - : Elsevier BV. - 0375-6742 .- 1879-1689. ; 170, s. 148-156
-
Tidskriftsartikel (refereegranskat)abstract
- This study focuses on fluorine (F) concentrations and solid-phase speciation in Quaternary deposits, including till, sorted sediments (gravel, sand, clay/silt) and organic-rich soil types, in an area in southeast Sweden underlain by 1.8 Ga granites and quartz monzodiorites with moderate F concentrations (0.11-0.13 wt%) and an outcrop (5 km in diameter) of 1.45 Ga granite (the Gotemar granite) with high to very high F concentrations (0.38-0.54 wt%). Eighteen <1 to 5 m thick profiles were sampled both upon and in the vicinity of the Gotemar granite. The F concentrations in the Quaternary deposits were considerably lower than in the underlying fresh bedrock, with the overall highest concentrations in glacial clay having values up to 660 ppm. A contributing factor to the low F concentrations in the till, as compared to the fresh rock, is release and leaching of fluoride (F-) during alteration of biotite and amphiboles to secondary minerals. Sequential chemical extractions showed that the F in the Quaternary deposits exists mainly in the residual fraction, and also to a substantial extent in phases extractable with hydroxylamine hydrochloride in the till and in phases extractable with Na pyrophosphate in the organic-rich soil types. These features indicate that after release via alteration of primary minerals, F- has to a significant extent been scavenged by Fe/Al (and perhaps Mn) oxyhydroxides in the till and by labile organic matter in the organic soil types. The high F- concentrations previously reported for stream waters and regolith groundwaters in the area are due to weathering and leaching of the Quaternary deposits and discharge of fluoride-rich waters from underlying bedrock fractures. (C) 2016 Elsevier B.V. All rights reserved.
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| 44. |
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| 45. |
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| 46. |
- Berger, Tobias, et al.
(författare)
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Impact of a Fluorine-Rich Granite Intrusion on Levels and Distribution of Fluoride in a Small Boreal Catchment
- 2012
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Ingår i: Aquatic geochemistry. - : Springer Science and Business Media LLC. - 1380-6165 .- 1573-1421. ; 18:2, s. 77-94
-
Tidskriftsartikel (refereegranskat)abstract
- This paper explores the influence of a fluorine-rich granite on fluoride concentration in a small boreal catchment in northern Europe. The materials include stream water and shallow groundwater sampled in spatial and temporal dimensions, and analytical data on fluoride and a number of ancillary variables. Fluoride increased strongly towards the lower reaches of the catchment—at the stream outlet the concentrations were up to 4.2 mg L −1 and 1.6–4.7 times higher than upstream. Additionally, fluoride concentrations were particularly high in groundwater and small surface-water bodies (including quarries) above or in direct contact with the granite and showed a strong inverse correlation with water discharge in the stream. Taken together, these data and patterns pin-point the granite intrusion as the ultimate source, explaining the abundance and distribution of dissolved fluoride within the catchment. The granite most likely deliver fluoride to the stream by three mechanisms: (1) weathering of the fine fraction of glacial deposits, derived from the granite and associated fluorine-rich greisen alterations, (2) large relative input of baseflow, partially originating in the granite and greisen, into the lower reaches during low flow in particular, and (3) water-conducting fractures or fracture zones running through the fluorine-rich granite and greisen.
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| 47. |
- Berger, Tobias, et al.
(författare)
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The impact of fluoride on Al abundance and speciation in boreal streams
- 2015
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Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 409, s. 118-124
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Tidskriftsartikel (refereegranskat)abstract
- The impact of fluoride on the abundance and speciation of aluminium (Al) was investigated in three boreal streams characterised by overall high concentrations of fluoride and dissolved organic matter. Stream-water sampling was carried out several times a year for at least 4 years, and a chemical equilibrium model (Visual MINTEQ) was applied in order to model the proportion of colloidal and organically/inorganically complexed Al in the waters. The Al concentrations in filtered (0.45 μm) water samples were inversely correlated with pH, and reached values up to approximately 1. mg/L during low pH conditions (pH < 6.0). In a stream with high fluoride concentrations, as compared to a similar stream with only moderately elevated fluoride concentrations, the Al concentrations were consistently elevated. For the stream with high concentrations of fluoride and Al, the model predicted both high concentrations and proportions of Al-fluoride complexation. This prediction indicates that high fluoride levels contribute to raise both the Al abundance and the ratio of inorganic to organic Al complexation in stream water. In contrast, for another stream with high fluoride concentrations and consistently high (near neutral) pH, there was no evidence of fluoride affecting Al concentration or complexation. These results show that it is important to focus future studies on the role of high levels of dissolved fluoride on both the speciation and the toxicity of Al in stream water.
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| 48. |
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| 49. |
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| 50. |
- Boman, Anton, et al.
(författare)
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Impact of isostatic land uplift and artificial drainage on oxidation of brackish-water sediments rich in metastable iron sulfide
- 2010
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 74:4, s. 1268-1281
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Tidskriftsartikel (refereegranskat)abstract
- This study examines the dynamics of sulfur and trace elements (As, Co, Mo, Ni, Ti and Zn) when brackish-water sediments, unusually rich in metastable iron sulfide (probably a mixture of mackinawite and greigite), are brought into the oxidation zone by postglacial isostatic land uplift and farmland drainage. When subaqueous sediments approach the sea level, metastable iron sulfide is oxidized in the upmost layers and pyrite preserved and even accumulated concomitantly trapping Co, Ni and Zn but not As and Mo. When the land uplift has brought the sediments above sea level and natural drainage thus is initiated, the pyrite is oxidized and Co, Ni and Zn are released and transported down the profile. If this setting remained undisturbed, the slightly oxidized sediment (unripe soil) would become covered by peat and thus protected from further oxidation and metal translocation. Often these sediments are, however, artificially drained resulting in extensive oxidation and fast soil-profile development. The soil is an acid sulfate (AS) soil, characterized by low pH (<4), extensive leaching of metals and an abundance of disseminated brownish Fe(III) precipitates. We suggest that the fast soil development is due to initial oxidation of metastable iron sulfide, followed by pyrite oxidation. Drain bottom sediment, which in terms of chemistry and S-isotopes resembled that of the surfacing sea bottom strata, acted during the sampling period as a sink for metals. The abundant preservation of metastable iron sulfide below the groundwater table, even long periods after uplift above the sea level, is a puzzling feature. We suggest that it is the net result of sulfur starvation, an abundance of Fe(II) and strongly reducing conditions. (C) 2009 Elsevier Ltd. All rights reserved.
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