| 1. |
- Shaheen, S. M., et al.
(författare)
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Redox chemistry of vanadium in soils and sediments : Interactions with colloidal materials, mobilization, speciation, and relevant environmental implications - A review
- 2019
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier. - 0001-8686 .- 1873-3727. ; 265, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Vanadium (V), although serving as an important component of industrial activities, has bioinorganic implications to pose highly toxic hazards to humans and animals. Soils and sediments throughout the world exhibit wide ranges of vanadium concentrations. Although vanadium toxicity varies between different species, it is mainly controlled by soil redox potential (E H ). Nonetheless, knowledge of the redox geochemistry of vanadium lags in comparison to what is known about other potentially toxic elements (PTEs). In particular, the redox-induced speciation and mobilization of vanadium in soils and sediments and the associated risks to the environment have not been reviewed to date. Therefore, this review aims to address 1) the content and geochemical fate of vanadium in soils and sediments, 2) its redox-induced release dynamics, 3) redox-mediated chemical reactions between vanadium and soil organic and inorganic colloidal materials in soil solution, 4) its speciation in soil solution and soil-sediments, and 5) the use of advanced geochemical and spectroscopic techniques to investigate these complex systems. Vanadium (+5) is the most mobile and toxic form of its species while being the thermodynamically stable valence state in oxic environments, while vanadium (+3) might be expected to be predominant under euxinic (anoxic and sulfidic) conditions. Vanadium can react variably in response to changing soil E H : under anoxic conditions, the mobilization of vanadium can decrease because vanadium (+5) can be reduced to relatively less soluble vanadium (+4) via inorganic reactions such as with H 2 S and organic matter and by metal-reducing microorganisms. On the other hand, dissolved concentrations of vanadium can increase at low E H in many soils to reveal a similar pattern to that of Fe, which may be due to the reductive dissolution of Fe(hydr)oxides and the release of the associated vanadium. Those differences in vanadium release dynamics might occur as a result of the direct impact of E H on vanadium speciation in soil solution and soil sediments, and/or because of the E H -dependent changes in soil pH, chemistry of (Fe)(hydr)oxides, and complexation with soil organic carbon. Release dynamics of vanadium in soils may also be affected positively by soil pH and the release of aromatic organic compounds. X-ray absorption spectroscopy (XAS) is a powerful tool to investigate the speciation of vanadium present in soil. X-ray absorption near edge structure (XANES) is often used to constrain the average valence state of vanadium in soils and sediments, and in limited cases extended X-ray absorption fine structure (EXAFS) analysis has been used to determine the average molecular coordination environment of vanadium in soil components. In conclusion, this review presents the state of the art about the redox geochemistry of vanadium and thus contributes to a better understanding of the speciation, potential mobilization, and environmental hazards of vanadium in the near-surface environment of uplands, wetlands, and agricultural ecosystems as affected by various colloidal particles. Further research is needed to elucidate the geochemistry and speciation of vanadium in the dissolved, colloidal, and soil sediments phases, including the determination of factors that control the redox geochemistry of vanadium.
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| 2. |
- Downing, Andrea S., et al.
(författare)
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Unlocking the unsustainable rice-wheat system of Indian Punjab : Assessing alternatives to crop-residue burning from a systems perspective
- 2022
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Ingår i: Ecological Economics. - : Elsevier BV. - 0921-8009 .- 1873-6106. ; 195
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Tidskriftsartikel (refereegranskat)abstract
- Crop residue burning in Indian Punjab emits particulate matter with detrimental impacts on health, climate and that threaten agricultural production. Though legal and technological barriers to residue burning exist – and alternatives considered more profitable to farmers – residue burning continues. We review black carbon (BC) emissions from residue burning in Punjab, analyse social-ecological processes driving residue burning, and rice and wheat value-chains. Our aims are to a) understand system feedbacks driving agricultural practices in Punjab; b) identify systemic effects of alternatives to residue burning and c) identify companies and financial actors investing in agricultural production in Punjab. We find feedbacks locking the system into crop residue burning. The Government of India has greatest financial leverage and risk in the current system. Corporate stakeholders have little financial incentive to enact change, but sufficient stakes in the value chains to influence change. Agricultural policy changes are necessary to reduce harmful impacts of current practices, but insufficient to bringing about sustainability. Transformative changes will require crop diversification, circular business models and green financing. Intermediating financial institutions setting sustainability conditions on loans could leverage these changes. Sustainability requires the systems perspective we provide, to reconnect production with demand and with supporting environmental conditions.
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| 3. |
- Ewerlöf, Sofia, et al.
(författare)
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DN Debatt. ”Låt gräsklipparen stå – för naturens skull”
- 2023
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Ingår i: Dagens nyheter (DN debatt). - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- In an era of species extinction and climate change, we should abandon the well-trimmed lawn and let gardens grow wilder, writes Anna Persson and other researchers and landscape architects on DN Debatt.
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| 4. |
- Baken, S., et al.
(författare)
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Ageing of vanadium in soils and consequences for bioavailability
- 2012
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Ingår i: European Journal of Soil Science. - : Elsevier. - 1351-0754 .- 1365-2389. ; 63:6, s. 839-847
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Tidskriftsartikel (refereegranskat)abstract
- Total vanadium (V) concentrations in soils commonly range from 20 to 120 mg kg-1. Vanadium added directly to soils is more soluble than geogenic V and can be phytotoxic at doses within this range of background concentrations. However, it is unknown how slow sorption reactions change the fate and effect of added V in soils. This study addresses the changes in V solubility, toxicity and bioavailability in soils over time. Four soils were amended with pentavalent V in the form of a soluble vanadate salt, and extractable V concentrations were monitored over 100 days. The toxicity to barley and tomato plants was evaluated in freshly spiked soils and in the corresponding aged soils that were equilibrated for up to 330 days after spiking. The V concentrations in 0.01 m CaCl2 soil extracts decreased approximately two-fold between 14 and 100 days after soil spiking, and the reaction kinetics were similar for all soils. The phytotoxicity of added V decreased on average two-fold between freshly spiked and aged soils. The reduced toxicity was associated with a corresponding decrease in V concentrations in the isolated soil solutions and in the shoots. The V speciation in the soil solution of the aged soils was dominated by V(V); less than 8% was present as V(IV). Oxalate extractions suggest that the V(V) added to soils is predominantly sorbed onto poorly crystalline oxyhydroxides. It is concluded that the toxicity of V measured in freshly spiked soils may not be representative of soils subject to a long-term V contamination in the field.
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| 5. |
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| 6. |
- Johansson, Emma, et al.
(författare)
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Hydrological and meteorological investigations in a periglacial lake catchment near Kangerlussuaq, west Greenland - presentation of a new multi-parameter data set
- 2015
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 7:1, s. 93-108
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Tidskriftsartikel (refereegranskat)abstract
- Few hydrological studies have been conducted in Greenland, other than on glacial hydrology associated with the ice sheet. Understanding permafrost hydrology and hydroclimatic change and variability, however, provides key information for understanding climate change effects and feedbacks in the Arctic landscape. This paper presents a new, extensive, and detailed hydrological and meteorological open access data set, with high temporal resolution from a 1.56 km(2) permafrost catchment, with a lake underlain by a through-talik close to the ice sheet in the Kangerlussuaq region, western Greenland. The paper describes the hydrological site investigations and utilized equipment, as well as the data collection and processing. The investigations were performed between 2010 and 2013. The high spatial resolution, within the investigated area, of the data set makes it highly suitable for various detailed hydrological and ecological studies on catchment scale. The data set is available for all users via the PANGAEA database, http://doi.pangaea.de/10.1594/PANGAEA.836178.
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| 7. |
- Larsson, Maja, et al.
(författare)
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Vanadium bioavailability in soils amended with blast furnace slag
- 2015
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 296, s. 158-165
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Tidskriftsartikel (refereegranskat)abstract
- Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800mgVkg-1) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment.
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| 8. |
- Modén, Carl S., 1979-
(författare)
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Micromechanics of softwoods in the transverse plane : effects on cell and annual ring scales
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Transverse mechanical properties of wood are important in many practial applications and an interesting scientific subject. A very low transverse shear modulus has been identified in spruce, which causes large strain concentrations in wood structures. In this thesis, experimental characterization of local density variations as well as local strain fields are carried out using the SilviScan apparatus and digital speckle photography, respectively. This is combined with micromechanical modeling based on hexagonal wood cells in combination with finite element analysis. Problems addressed include the moduli in the transverse plane, including variations at the scale of individual annual rings. The relative importance of cell wall bending and stretching deformation mechanisms is analysed as a function of wood cell geometry, relative density and direction of loading (radial, tangential and shear). Transverse anisotropy is also analyzed, including its dependency of earlywood and latewood characteristics. The wood cell shape angle variation and density effects are sufficient to explain transverse anisotropy in softwoods (no ray effects), and the influence of earlywood/latewood ratio is explained. As a practical test method for shear modulus measurements, an off-axis compression test with full-field strain determination is proposed. The advantage is a simple fixture and large region of representative strain required for a heterogeneous material such as wood. As an alternative, the single cube apparatus (SCA) for shear tests is evaluated. The SCA is used to determine the shear strain distribution within the annual rings. Based on the density distribution of the shear test specimen and a micromechanics model, a finite element model is developed, and predictions are compared with the measured shear strains. The agreement between predicted and measured shear strains at the annual ring scale are remarkably good. It shows that the low GRT of spruce is due to the low earlywood density and the large cell wall bending deformation resulting from shear loading. Furthermore, it illustrates the need for improved understanding of annual ring scale effects. For example, fairly low transverse global loads will lead to lage local shear strains.
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| 9. |
- Sjöstedt, Carin S., et al.
(författare)
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Chemical Equilibrium Modeling of Organic Acids, pH, Aluminum, and Iron in Swedish Surface Waters
- 2010
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:22, s. 8587-8593
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Tidskriftsartikel (refereegranskat)abstract
- A consistent chemical equilibrium model that calculates pH from charge balance constraints and aluminum and iron speciation in the presence of natural organic matter is presented. The model requires input data for total aluminum, iron, organic carbon, fluoride, sulfate, and charge balance ANC. The model is calibrated to pH measurements (n = 322) by adjusting the fraction of active organic matter only, which results in an error of pH prediction on average below 0.2 pH units. The small systematic discrepancy between the analytical results for the monomeric aluminum fractionation and the model results is corrected for separately for two different fractionation techniques (n = 499) and validated on a large number In = 3419) of geographically widely spread samples all over Sweden. The resulting average error for inorganic monomeric aluminum is around 1 mu M. In its present form the model is the first internally consistent modeling approach for Sweden and may now be used as a tool for environmental quality management Soil gibbsite with a log *K-s of 8.29 at 25 degrees C together with a pH dependent loading function that uses molar Al/C ratios describes the amount of aluminum in solution in the presence of organic matter if the pH is roughly above 6.0.
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| 10. |
- Van Vliet, Jolanda S, et al.
(författare)
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Overweight perception among adolescent girls in relation to appearance of female characteristics
- 2014
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Ingår i: Paediatrics and Health. - : Herbert Open Access Journals. - 2052-935X. ; 2:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Background: Overweight perception has been shown to be important for health related adolescent behavior, particularly in girls. Body perception may be affected by bodily changes, especially changes visible for others. Female pubertal development is characterized by many physical changes, such as accelerated growth and altered body fat distribution. This study examined the role of appearance of female characteristics in the risk for overweight perception among healthy adolescent girls.Methods: 220 girls, aged 11–16, provided self-reports on body perception and pubertal maturation before anthropometric measurements of height, weight, hip and waist circumference (WC). Logistic regression modeling was used to study the appearance of pubertal characteristics in relation to body perception.Results: Of the 76 girls (35%) perceiving themselves as overweight, only 14 and 36 girls were overweight according to body mass index and waist circumference respectively. Girls reporting breast development and acne (n=144) were more likely to perceive themselves as overweight than girls who did not report this appearance (n=76). These findings persist after adjusting for overweight according to WC. Non-overweight (n=170) rather than overweight girls reporting characteristics (n=50) were at risk of perceiving themselves overweight.Conclusions: Girls may confuse natural changes occurring during adolescent development with being overweight. It is therefore important to improve the understanding about the physical changes that normally occur during puberty along with the girls' own perception of these bodily changes among girls themselves, their parents, at schools, and other healthcare services.
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