| 1. |
- Moberg, Christina, et al.
(författare)
-
De unga gör helt rätt när de stämmer staten
- 2022
-
Ingår i: Aftonbladet. - 1103-9000.
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
|
|
| 2. |
- Alakangas, Lena, et al.
(författare)
-
Changes of groundwater quality in sulphide-bearing mine-tailings as a result of remediation at Kristineberg, northern Sweden
- 2007
-
Ingår i: Mining and the Environment International Conference. - : Centre for Environmental Monitoring, Laurentian University. - 9780886670726
-
Konferensbidrag (refereegranskat)abstract
- At the Kristineberg mine in northern Sweden, sulphide-rich tailings left open for 50 years were remediated in 1996 by applying double dry cover on one part of an impoundment, and raised groundwater level combined with simple till cover on the other part. Groundwater pipes installed in the impoundment were sampled from 1998 during a period of 6 years. The results showed that the groundwater quality varied considerably in the impoundment, even under the same type of cover. Secondarily retained Fe, S, Mg, Mn and Z were remobilised when the groundwater was raised. In the part with raised groundwater level, the average concentration of Fe ranged from 2700 to 9000mg/l in 1998, and the range for S was 2200 to 7000mg/l. During 2003 the average concentrations had decreased and ranged between 150 and 900 mg/l for Fe and between 130 and 900 mg/l for S. The improvement of the water quality was caused by inflow of less contaminated groundwater and decreasing sulphide oxidation rate. The redox potential generally decreased and pH increased. The concentrations of Cd, Cu and Pb in groundwater decreased rather rapidly all over the impoundment after remediation. In areas with relatively high pH and low redox potential, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn were almost depleted.
|
|
| 3. |
|
|
| 4. |
- Alakangas, Lena, et al.
(författare)
-
Estimation of temporal changes in oxidation rates of sulphides in copper mine tailings at Laver, Northern Sweden
- 2010
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 408:6, s. 1386-1302
-
Tidskriftsartikel (refereegranskat)abstract
- Tailings containing pyrrhotite were deposited in an impoundment at a copper mine at Laver, Northern Sweden, which operated between 1936 and 1946. Since then the oxidation of sulphides has acidified recipient water courses and contaminated them with metals. Measurements from surface water sampled in 1993, 2001 and 2004-05 from a brook into which the tailing impoundment drains indicate that the amounts of sulphide-associated elements such as Cu, S and Zn released into the brook have decreased over time, while pH has increased. The mass transport of S in the brook during 1993 and 2001 corresponded well with the amount of S estimated to be released from the tailings by oxidation. Secondary precipitates such as covellite and gypsum, which can trap sulphur, were shown in earlier studies to be present in only low amounts. The annual release of elements from the tailings was estimated from the volume of tailings assumed to oxidise each year, which depends on movement of the oxidation front with time. The results indicate that the oxidation rate in the tailings has decreased over time, which may be due to the increased distance over which oxygen needs to diffuse to reach unoxidised sulphide grains, or their cores, in the tailings.
|
|
| 5. |
- Alakangas, Lena, et al.
(författare)
-
Pilot-scale studies of different covers on unoxidised sulphide-rich tailings, northern Sweden : oxygen diffusion
- 2010
-
Ingår i: Mine Water and the Environment. - Ostrava : VSB - Technical University Ostrava, Faculty of Mining and Geology, Institute of Environmental Engineering. - 9788024817675 ; , s. 347-350
-
Konferensbidrag (refereegranskat)abstract
- The efficiency of five cover systems to decrease oxygen intrusion into sulphide-rich tailings was studied in pilot-scale test cells (5x5x3 m(3)). The covers consisted of clayey till, sewage sludge, fine-grained apatite concentrate or Trisoplast (a mixture of a polymer, bentonite and tailings sand) as sealing layers and unspecified till as protective cover. In one reference cell, tailings were uncovered. Oxygen concentrations below the entire covers were highest below the Trisoplast and apatite layers, and lowest below the sewage sludge layer. Effective diffusion coefficients (D-eff) and oxygen fluxes were estimated in the covers with non-oxygen-consuming sealing layers (clayey till and apatite). For the protective covers the Deff ranged between E-09 and E-07 m(2)/s, and for the sealing layers between E-10 and E-09 m(2)/s, and for the entire covers between E-10 and E-08 m(2)/s. Seasonal variations in D-eff were larger within the covers than between the different cover systems. Oxygen fluxes through the entire covers with clayey till and apatite ranged between 0.2 and 4 mole m(2)/year, which was a reduction of more than 99% compared to uncovered dry tailings.
|
|
| 6. |
|
|
| 7. |
- Alakangas, Lena, et al.
(författare)
-
Simulation of pyrite oxidation in fresh mine tailings under near-neutral conditions
- 2012
-
Ingår i: Journal of Environmental Monitoring. - 1464-0325 .- 1464-0333. ; 14:8, s. 2245-2253
-
Tidskriftsartikel (refereegranskat)abstract
- Sulphidic residual products from ore processing may produce acid rock drainage, when exposed to oxygen and water. Predictions of the magnitude of ARD and sulphide oxidation rates are of great importance in mine planning because they can be used to minimize or eliminate ARD and the associated economic and environmental costs. To address the lack of field data of sulphide oxidation rate in fresh sulphide-rich tailings under near-neutral conditions, determination and simulation of the rate was performed in pilot-scale at Kristineberg, northern Sweden. The quality of the drainage water was monitored, along with oxygen and carbon dioxide concentrations. The chemical composition of the solid tailings was also determined. The field data were compared to predictions from simulations of pyrite oxidation using a 1-D numerical model. The simulations' estimates of the amount of Fe and S released over a seven year period (52 kg and 178 kg, respectively) were in reasonably good agreement with those obtained by analysing the tailings (34 kg and 155 kg, respectively). The discrepancy is probably due to the formation of secondary precipitates such as iron hydroxides and gypsum; which are not accounted for in the model. The observed mass transport of Fe and S (0.05 and 1.0 kg per year, respectively) was much lower than expected on the basis of the simulations and the core data. Neutralization reactions involving carbonates in the tailings result in a near-neutral pH at all depths except at the oxidation front (pH < 5), indicating that the dissolution of carbonates was too slow for the acid to be neutralized, which instead neutralized deeper down in the tailings. This was also indicated by the reduced abundance of solid Ca at greater depths and the high levels of carbon dioxide both of which are consistent with the dissolution of carbonates. It could be concluded that the near-neutral pH in the tailings has no decreasing effect on the rate of sulphide oxidation, but does reduce the concentrations of dissolved elements in the drainage water due to the formation of secondary minerals. This means that sulphide oxidation rates may be underestimated if determined from drainage alone.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Barki-Harrington, Liza, et al.
(författare)
-
Requirement for direct cross-talk between B1 and B2 kinin receptors for the proliferation of androgen-insensitive prostate cancer PC3 cells
- 2003
-
Ingår i: Biochemical Journal. - 0264-6021. ; 371, s. 581-587
-
Tidskriftsartikel (refereegranskat)abstract
- Stimulation of endogenous kinin receptors promotes growth of androgen-independent prostate cancer PC3 cells via activation of the mitogenic extracellular-signal-regulated kinase (ERK) pathway. In the present study, we show that kinin-mediated mitogenic signalling and prostate-cell growth involves two subtypes of bradykinin (BK) receptors, B1R and B2R. Specific stimulation of either B1R or B2R by their respective agonists des-Arg(9)-BK and Lys-BK promoted ERK activation and cell growth, whereas selective blockade with specific antagonists des-Arg(9)-[Leu(8)]BK and Hoe 140 respectively obliterated this effect, indicating the presence of both receptor subtypes. However, blockade of B1R also inhibited B2R-mediated ERK activation and cell growth, and, similarly, antagonism of B2R inhibited the B1R-mediated response. Furthermore, both B1R and B2R agonists promoted internalization of B1R, whereas both receptor antagonists blocked this effect. The B1R ligands des-Arg(9)-BK and des-Arg(9)-[Leu(8)]BK had no effect on the binding of BK to B2R, as demonstrated by radioligand competitive binding studies. However, blockade of either B1R or B2R impaired the ability of the reciprocal receptor to produce inositol phosphates, suggesting that the interaction between B1R and B2R is proximal to activation of phospholipase C. These results provide evidence for the existence of B1R-B2R complexes in prostate cancer PC3 cells and demonstrate that antagonism of one receptor interferes with the signalling ability of the other, possibly at the level of receptor-Galpha(q) protein coupling. Selective inhibition of B1R, which is up-regulated in injured and cancerous tissue, may be beneficial for the treatment of advanced prostate cancer.
|
|
| 11. |
|
|
| 12. |
- Engen, Kristine, et al.
(författare)
-
Autoantibodies to the N-Methyl-D-Aspartate Receptor in Adolescents With Early Onset Psychosis and Healthy Controls
- 2020
-
Ingår i: Frontiers in Psychiatry. - : Frontiers Media SA. - 1664-0640. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- Background Autoantibodies to theN-methyl-D-aspartate receptor (NMDAR-Abs) in autoimmune encephalitis have been associated with prominent psychiatric symptoms. The aims of the present study are to identify the prevalence of NMDAR-Abs in adolescents with early onset psychosis disorders (EOP) and healthy controls (HC) and examine its clinical significance. Method Plasma samples were acquired from 46 adolescent EOP patients and 69 age- and sex matched HC, and assessed for the presence of immunoglobulin G NMDAR-Abs. All participants underwent psychiatric evaluation, neurological examination and head magnetic resonance imaging. Results NMDAR-Abs were detected in three of 46 (6.5%) EOP patients and in two of 69 (2.9%) HC. One NMDAR-Abs EOP patient presented with unusual psychopathology and minor T1 weighted lesions of vasculopathological origin located bi-frontally and in the basal ganglia, and had a recent diagnosis of a separate autoimmune disease. One NMDAR-Ab HC displayed a T2 weighted FLAIR hyperintensity lesion in the left frontal lobe. The remaining three NMDAR-Ab participants were two EOP patients without neurological or radiological findings, and one HC without any clinical findings. Conclusions We report that a small number of EOP patients and HC have NMDAR-Abs with a similar frequency in both groups. The presence of the antibodies was not associated with any distinctive clinical or radiological features. Detection of the antibodies had no diagnostic implication, and a positive NMDAR antibody test must be carefully interpreted and reviewed within the individual clinical context.
|
|
| 13. |
|
|
| 14. |
- Feiccabrino, James, et al.
(författare)
-
Improving surface based precipitation phase determination through air mass boundary identification
- 2012
-
Ingår i: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694 .- 1998-9563 .- 2224-7955. ; 43:3, s. 179-191
-
Tidskriftsartikel (refereegranskat)abstract
- Most hydrological models apply one empirical formula based on surface air temperature for precipitation phase determination. This approach is flawed as surface precipitation phase results from energy exchanges between falling precipitation and air in the lower atmosphere. Different lower atmospheric conditions cause different precipitation phase probabilities for near-freezing temperatures. Often directly measured lower atmospheric conditions are not available for remote areas. However, meteorological observations occurring before/after similar air mass boundaries have similar atmospheric conditions that vary from most other observations. Therefore, hydrological models can indirectly account for lower atmospheric conditions. Twenty years of manual observations from eight United States weather stations were used to compare misclassified precipitation proportions when analyzing (a) all precipitation observations together and (b) identified cold air mass boundary observations (CAB) and non-CAB observations separately. The CAB observations were identified by a rapid surface air temperature decrease. A two-surface air temperature threshold method with one threshold all snow (T-S degrees C) and one all rain (T-R degrees C) having a linear snow fraction decrease between the thresholds was used. The T-S (0 degrees C), and T-R (4 degrees C) values for CAB were 1 degrees C warmer than for non-CAB (-1 degrees C, 3 degrees C). Analyzing CAB and non-CAB separately reduced misclassified precipitation 23%, from 7.0 to 5.4%.
|
|
| 15. |
- Feiccabrino, James, et al.
(författare)
-
Meteorological Knowledge Useful for the Improvement of Snow Rain Separation in Surface Based Models
- 2015
-
Ingår i: Hydrology. - : MDPI AG. - 2306-5338. ; 2:4, s. 266-288
-
Tidskriftsartikel (refereegranskat)abstract
- An accurate precipitation phase determination—i.e., solid versus liquid—is of paramount importance in a number of hydrological, ecological, safety and climatic applications. Precipitation phase can be determined by hydrological, meteorological or combined approaches. Meteorological approaches require atmospheric data that is not often utilized in the primarily surface based hydrological or ecological models. Many surface based models assign precipitation phase from surface temperature dependent snow fractions, which assume that atmospheric conditions acting on hydrometeors falling through the lower atmosphere are invariant. This ignores differences in phase change probability caused by air mass boundaries which can introduce a warm air layer over cold air leading to more atmospheric melt energy than expected for a given surface temperature, differences in snow grain-size or precipitation rate which increases the magnitude of latent heat exchange between the hydrometers and atmosphere required to melt the snow resulting in snow at warmer temperatures, or earth surface properties near a surface observation point heating or cooling a shallow layer of air allowing rain at cooler temperatures or snow at warmer temperatures. These and other conditions can be observed or inferred from surface observations, and should therefore be used to improve precipitation phase determination in surface models.
|
|
| 16. |
- Feiccabrino, James, et al.
(författare)
-
Precipitation phase discrimination by dew point and air temperature
- 2008
-
Ingår i: Proceedings of the Western Snow Conference, Kailua-Kona, Hawaii, April, 16 - 19, 2007. - Soda Springs, Calif : Western Snow Conference. ; , s. 141-145
-
Konferensbidrag (refereegranskat)abstract
- Correctly reported precipitation phases are crucial for estimation of snow storage in hydrological, regional and global climate models. Precipitation phase is especially critical for models simulating processes in tree canopies, since the canopy storage capacity is about one order of magnitude larger for snow than rain. The number of manned meteorological stations is decreasing, making determination of precipitation phase more difficult. Most hydrological models use an air temperature threshold to separate rain from snow, but there are indications that a dew-point temperature threshold might work better. This study utilized forty-five years of three-hour man-made observations for nineteen Swedish station ranging from 55˚N to 68˚N consisting of precipitation mass and phase, air and dew point temperatures. Precipitation events classed as snow or rain, excluding mixed precipitation, were used for the initial analysis. Air temperature was found to be a better indicator of precipitation phase then dew point temperature. On occasion 0˚C is used as an air temperature threshold, but if the air temperature rain/snow threshold 0˚C is replaced by 1.0˚C the misclassified precipitation would be reduced by almost half in Sweden. Further analysis to identify mixed precipitation, totaling 16% of the precipitation is also included.
|
|
| 17. |
|
|
| 18. |
- Feiccabrino, James, et al.
(författare)
-
Surface-based precipitation phase determination methods in hydrological models
- 2013
-
Ingår i: Hydrology Research. - : IWA Publishing. - 1998-9563 .- 0029-1277 .- 2224-7955. ; 44:1, s. 44-57
-
Tidskriftsartikel (refereegranskat)abstract
- We compared solid and liquid precipitation mass output from three categories of common model precipitation phase determination schemes (PPDS) to the recorded precipitation phase in a set of 45 years of 3-hour manual meteorological observations from 19 Swedish meteorological stations. In the first category of rain/snow thresholds, it was found that rain/snow air temperature threshold (ATT) is a better precipitation phase indicator than a rain/snow dew point temperature threshold. When a rain/snow ATT of 0.0 degrees C (a default value used in some recent models) was replaced by 1.0 degrees C, misclassified precipitation was reduced by almost one half. A second category of PPDS use two ATTs, one snow and one rain, with a linear decrease in snow fraction between. This category identified precipitation phase better than a rain/snow ATT at 17 stations. Using all observations from all the meteorological stations, a final category using an air-temperature-dependent snow probability curve resulted in slightly lower misclassified precipitation mass at 13 of the 19 stations. However, schemes from the linear decrease in snow fraction category had the lowest misclassified precipitation mass at four meteorological stations.
|
|
| 19. |
|
|
| 20. |
- Granlund, Nils, et al.
(författare)
-
Laboratory study of the influence of salinity on the relationship between electrical conductivity and wetness of snow
- 2010
-
Ingår i: Hydrological Processes. - : John Wiley & Sons. - 0885-6087 .- 1099-1085. ; 24:14, s. 1981-1984
-
Tidskriftsartikel (refereegranskat)abstract
- Snow water equivalent of a snowpack can be estimated using ground-penetrating radar from the radar wave two-way travel time. However, such estimates often have low accuracy when the snowpack contains liquid water. If snow wetness is known, it is possible to take it into account in the estimates; it is therefore desirable to be able to determine snow wetness from already available radar data. Our approach is based on using radar wave attenuation, and it requires that the relationship between electrical conductivity and wetness of snow should be known. This relationship has been tentatively established in previous laboratory experiments, but only for a specific liquid water salinity and radar frequency. This article presents the results of new laboratory experiments conducted to investigate if and how this relationship is influenced by salinity. In each experiment, a certain amount of snow was melted and a known amount of salt (different for different experiments) was added to the water. Water salinity was measured, and the water was added step-wise to a one-meter thick snowpack, with radar measurements taken between additions of water. Our experiments have confirmed the earlier established linear relationship between electrical conductivity and wetness of snow, and they allow us to suggest that the influence of liquid water salinity on electrical conductivity is negligible when compared to the influence of liquid water content in snow.
|
|
| 21. |
- Granlund, Nils, et al.
(författare)
-
Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar
- 2009
-
Ingår i: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694 .- 1998-9563 .- 2224-7955. ; 40:1, s. 33-44
-
Tidskriftsartikel (refereegranskat)abstract
- Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Granlund, Nils, et al.
(författare)
-
Towards better predictions of snow melt runoffs : Measuring Snow Depth and Density Using Ground Penetrating Radar
- 2009
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Snow melt runoff predictions by hydrological models are essential for efficient hydropower production in the Scandinavian countries, similar to many areas with a substantial amount of snow precipitation. Operational models in Sweden are currently based on precipitation and temperature as the main input variables and calibrated with runoff data, but there is an interest to make better use of new measurement systems for distributed snow data, especially the total amount of snow in the catchment area of interest. The main objective of our project is to investigate the potential improvements in runoff predictions in relation to the choice of model structure and measurement systems, as well as measurement accuracy. This involves comparing different methods for estimating the total amount of snow in a catchment area as well as improving their accuracy. Here we present the result of such comparison based on data from case studies conducted in Sweden. Our approach involves automated single point measurements over a long period in combination with high resolution distributed measurements over a large area during critical periods. Stationary measurements are performed at a snow measurement station, with snow density and wetness estimated with a low-frequency impedance sensor band, snow depth measured using an ultrasonic depth gauge, and temperature measured at several (fixed) snow depths and at the snow surface. The station, located at Lake Korsvattnet in Swedish mountains, operates continuously during the whole winter season. Measurements of snow depth and density over large lateral distances are performed using multi-offset ground penetrating radar (GPR) operated from a snow mobile. These measurements are conducted once a year, in late winter, when the amount of snow is expected to reach its maximum before snow melt begins. Since 2007 and during the duration of the project, yearly measurements have been and will be taken in two Swedish mountain basins important for hydropower, Lake Korsvattnet and Lake Kultsjön. The radar system used is a multi-channel RAMAC/GPR system with shielded 800 and 1600 MHz antennas. The antennas are attached to a snow mobile sledge forming an array, which allows us to use the common midpoint method to calculate both radar propagation velocity and two-way travel time of radar pulses. For dry snow this gives snow density and depth via an empirical formula establishing the relationship between electrical permittivity (i.e. propagation velocity) and snow density. Note that for wet snow additional information about liquid water content in snow is required, which can be estimated, for example, from radar wave attenuation. However, for the purpose of this presentation we assume that the snow is dry. The results of GPR measurements taken from a snow mobile are compared with results obtained by two other methods. The first comparison is with manual measurements taken with traditional snow tubes along a 1000 m measurement profile at the area of Lake Korsvattnet. In this case a log-linear relationship between snow depth and density is used to interpret GPR data (note that this relationship is obtained from analysis of radar data itself). The other comparison is with GPR measurements taken from a helicopter along a 12 km transect in the area of Lake Kultsjön.
|
|
| 25. |
|
|
