29 results on '"Torseth, K."'
Search Results
2. Regional Aerosol Optical Properties and Radiative Impact of the Extreme Smoke Event in the European Arctic in Spring 2006
- Author
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Lund Myhre, C, Toledano, C, Myhre, G, Stebel, K, Yttri, K, Aaltonen, V, Johnsrud, M, Frioud, M, Cachorro, V, deFrutos, A, Lihavainen, H, Campbell, J, Chaikovsky, A, Shiobara, M, Welton, E, and Torseth, K
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Environment Pollution - Abstract
In spring 2006 a special meteorological situation occurred in the European Arctic region giving record high levels of air pollution. The synoptic situation resulted in extensive transport of pollution predominantly from agricultural fires in Eastern Europe into the Arctic region and record high air-pollution levels were measured at the Zeppelin observatory at Ni-Alesun(78deg 54'N, 11deg 53'E) in the period from 25 April to 12 May. In the present study we investigate the optical properties of the aerosols from this extreme event and we estimate the radiative forcing of this episode. We examine the aerosol optical properties from the source region and into the European Arctic and explore the evolution of the episode and the changes in the optical properties. A number of sites in Eastern Europe, Northern Scandinavia and Svalbard are included in the study. In addition to AOD measurements, we explored lidar measurements from Minsk, ALOMAR (Arctic Lidar Observatory for Middle Atmosphere Research at Andenes) and Ny-Alesund. For the AERONET sites included (Minsk, Toravere, Hornsund) we have further studied the evolution of the aerosol size. Importantly, at Svalbard it is consistency between the AERONET measurements and calculations of single scattering albedo based on aerosol chemical composition. We have found strong agreement between the satellite dally MODIS AOD and the ground-based AOD observations. This agreement is crucial for the radiative forcing calculations. We calculate a strong negative radiative forcing for the most polluted days employing the analysed ground based data, MODIS AOD and a multi-stream model for radiative transfer of solar radiation.
- Published
- 2007
3. Processes affecting deposition of oxidised nitrogen and associated species in the coastal areas of Norway
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Tørseth, K, Semb, A, Schaug, J, Hanssen, J.E, and Aamlid, D
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- 2000
- Full Text
- View/download PDF
4. Air pollution trends in the EMEP region between 1990 and 2012 (Joint Report of the EMEP Task Force on Measurements and Modelling (TFMM), Chemical Co-ordinating Centre (CCC), Meteorological Synthesizing Centre-East (MSC-E), Meteorological Synthesizing Cent
- Author
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Colette, A., Aas, W., Braban, C. F., Putaud, J., Solberg, S., Tarasova, O., Querol, X., SAUVAGE, S., Torseth, K., Institut National de l'Environnement Industriel et des Risques (INERIS), Norwegian Institute for Air Research (NILU), Centre for Ecology and Hydrology, World Meteorological Organization (WMO), Institute of Environmental Assessment and Water Research (IDAEA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), École des Mines de Douai (Mines Douai EMD), and Institut Mines-Télécom [Paris] (IMT)
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[SDE]Environmental Sciences ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience; abstract simple
- Published
- 2016
5. New Directions: The future of European urban air quality monitoring
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Kuhlbusch, T.A.J. Quincey, P. Fuller, G.W. Kelly, F. Mudway, I. Viana, M. Querol, X. Alastuey, A. Katsouyanni, K. Weijers, E. Borowiak, A. Gehrig, R. Hueglin, C. Bruckmann, P. Favez, O. Sciare, J. Hoffmann, B. EspenYttri, K. Torseth, K. Sager, U. Asbach, C. Quass, U.
- Published
- 2014
6. Air Quality Monitoring Strategies for Urban Areas â€' A Data Base on New Monitoring Technologies, New Metrics and Proxies
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Weijers, E.P., Kuhlbusch, T.A.J., Viana, M., Borowiak, A., Torseth, K., Querol, X., Quincey, P., Gehrig, R., Hüglin, C, Katsyouanni, K., Quass, U., and Energieonderzoek Centrum Nederland
- Abstract
n.v.t.
- Published
- 2012
7. The Importance of Nitrogen Oxides for the Exceedance of Critical Thresholds in the Nordic Countries
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Johansson, M., Suutari, R., Bak, J., Lovblad, G., Posch, M., Simpson, D., Tuovinen, J. -P, and Torseth, K.
- Published
- 2001
8. COST ES0602: towards a European network on chemical weather forecasting and information systems.
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Kukkonen, J., Klein, T., Karatzas, K., Torseth, K., Fahre Vik, A., San José, R., Balk, T., and Sofiev, M.
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ATMOSPHERIC chemistry ,WEATHER forecasting ,REAL-time computing ,BEST practices - Abstract
The article focuses on the COST Action ES0602 for effective integration of current assets for the efficient chemical weather forecasting in Europe. The collaboration of different sectors from 2007 to 2011 will concentrate on infrastructure development for near real-time exchange of input data. Moreover, the Action will offer recommendations on the best pattern in presenting and disseminating of chemical weather information for the public and decision makers.
- Published
- 2009
9. The global atmosphere watch reactive gases measurement network
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Schultz, M.G., Akimoto, H., Botenheim, J., Buchmann, B., Galbally, I.E., Gilge, S., Helmig, D., Koide, H., Lewis, A.C., Novelli, P.C., Plass-Dülmer, C., Ryerson, T.N., Steinbacher, M., Steinbrecher, R., Tarasova, O., Torseth, K., Thouret, V., and Zellweger, C.
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13. Climate action - Abstract
Long-term observations of reactive gases in the troposphere are important for understanding trace gas cycles and the oxidation capacity of the atmosphere, assessing impacts of emission changes, verifying numerical model simulations, and quantifying the interactions between short-lived compounds and climate change. The World Meteorological Organization’s (WMO) Global Atmosphere Watch (GAW) program coordinates a global network of surface stations some of which have measured reactive gases for more than 40 years. Gas species included under this umbrella are ozone, carbon monoxide, nitrogen oxides, and volatile organic compounds (VOCs). There are many challenges involved in setting-up and maintaining such a network over many decades and to ensure that data are of high quality, regularly updated and made easily accessible to users. This overview describes the GAW surface station network of reactive gases, its unique quality management framework, and discusses the data that are available from the central archive. Highlights of data use from the published literature are reviewed, and a brief outlook into the future of GAW is given. This manuscript constitutes the overview of a special feature on GAW reactive gases observations with individual papers reporting on research and data analysis of particular substances being covered by the program.
10. Assessing PM10 source reduction in urban agglomerations for air quality compliance
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Lazaridis Michalis, Aleksandropoulou, V, Eleftheriadis, K, Diapouli , E, Diapouli, E, and Torseth , K
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Air Pollutants ,Greece ,Urban agglomeration ,Public Health, Environmental and Occupational Health ,Environmental engineering ,General Medicine ,Management, Monitoring, Policy and Law ,Particulates ,Environmental Policy ,Air quality monitoring ,Source reduction ,Air Pollution ,Range (statistics) ,Environmental science ,Particulate Matter ,Cities ,Particle Size ,Frequency distribution ,Air--Pollution--Control,Air contaminants,Air pollutants,Air pollution,Air pollution control,Air toxics,Airborne pollutants,Atmosphere--Pollution,Contaminants, Air,Control of air pollution,Pollutants, Air,Toxics, Air,air pollution,air pollution control,air contaminants,air pollutants,air toxics,airborne pollutants,atmosphere pollution,contaminants air,control of air pollution,pollutants air,toxics air ,Air quality index ,Environmental Monitoring ,Weibull distribution - Abstract
Summarization: The objective of this work was to study PM(10) and PM(2.5) concentration data available from monitoring stations in two large urban agglomerations in Greece and to estimate the emissions reduction required for compliance with the EU Air Quality Standards (AQS) for particulate matter. The cities studied are namely the Athens and Thessaloniki Metropolitan Areas (AMA and TMA, respectively). PM(10) concentrations during the period 2001-2010 have been evaluated for 15 air quality monitoring stations in the two urban areas. It was found that the concentrations of PM(10) during the period studied constantly exceeded the threshold values at the traffic and industrial stations in TMA and most of the traffic sites in AMA. Most of the occurrences of non-attainment to the daily AQSs were observed during the winter period at all stations (more pronounced for TMA stations). The reduction in current emission source strength to meet the air quality goal was calculated by the rollback equation using PM(10) day-averaged concentrations over the selected period at each station. Among the lognormal and Weibull distributions, the lognormal distribution was found to best fit the frequency distributions of PM(10) concentrations at the selected stations. The results showed that the minimum reduction required in order to meet the AQS in the AMA ranges from approximately 20 to 38% and up to 11% for traffic and background stations, respectively. Reductions in the range of 31% for traffic and 44% for industrial areas in TMA are also required. The same methodology was applied to PM(2.5) concentrations in the AMA and showed that emission reductions up to 31% are necessary in order to meet the 2020 EU AQS. Finally, continuous concentration data of organic (OC) and elementary carbon (EC) in PM(2.5) were used to study the possibility of achieving specific emission attenuation objectives in AMA. Presented on: Journal of Environmental Monitoring
11. Changes of forest health in Norwegian boreal forests during 15 years
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Venn, K., Hylen, G., Framstad, E., Stuanes, A. O., Christophersen, N., Aamlid, D., Solberg, S., and Torseth, K.
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FOREST management ,FOREST health ,TAIGAS - Abstract
The Norwegian Monitoring Programme for Forest Damage has now been running since 1984. Its main objective has been monitoring the boreal forest conditions in relation to air pollution. Surveys of forests areperformed on plots in a nation-wide representative grid network, in a network of local countywise plots, and in a network of intensively monitored plots within the framework of the internationally coordinated UN/ECE ICP Forests. At intensively monitored plots, a number of measurements were performed, for example tree crown-condition assessments, foliar chemistry, air pollution, precipitation chemistry (open area and stand throughfall), soil and soil-water chemistry. Vitality criteria have shown a declining trend, expressed as reduced crown density and more of discolored trees, particularly in spruce forests. These results are similar to findings in other Scandinavian countries andcoincide with the general trend in Europe. Forest yield has increased in later years in most parts of Norway. Tree mortality in excess ofnormal is not recorded. Considering these results, it is reasonable to presume that most Norwegian forest ecosystems are generally in a good condition. Areas in the south-eastern part of the country, however, may have shown indications of a slightly reduced crown condition. These areas are located in a region with a relatively high load of air pollution and low buffering capacity against acidification. Although forest conditions generally depend on soil, tree age, climate, pests and diseases, and other natural stressors; air pollution loads add to, or may interact with, these factors. Most likely inciting factors(e.g. summer drought) have occurred and produced visual symptoms. The actual effect of the air pollution component is, therefore, difficult to estimate; however, its importance is not discounted. [ABSTRACT FROM AUTHOR]
- Published
- 2000
12. Human impacts on the nitrogen cycle: a global problem judged from a local perspective
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Mulder, J., Torseth, K., Vagstad, N., Hessen, D. O., Hindar, A., and Henriksen, A.
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NITROGEN , *BIOGEOCHEMISTRY - Abstract
This chapter revisits the major problems relating to manmade disturbances in the global nitrogen (N) cycle, and links the local findings from the project to the large-scale effects. The human transformationof atmospheric N2 to chemically and biologically more reactive species causes a number of environmental effects. The focus of this project has been budget estimates of N for two large watersheds with a set of subcatchments in southern Norway, accompanied by process studies to explain patterns of retention and runoff of N. Atmospheric inputs were close to 2.5 mg N m- 2 yr-1 and by far the dominant source of N for the sparsely populated, heathlanddominated watershed. Low retention and apparent N saturation could be accredited to high atmospheric inputs of N, but also hydrology, poorly developed soils and terrestrial P limitation. In this acidified watershed, nitrate contributed nearly 50% to surface water acidification, underlining the importance for strong cuts in NOx and NHx emissions. P concentrations were low, frequently < 1 mu g L- 1, causing high N:P ratios in runoff, and promotingP limitation both in freshwater and the nearshore marine recipient. For the agriculturally and forested watershed, atmospheric N deposition was < 1.5 mg N m-2 yr-1, and agricultural activities were the totally dominant source of N, yielding generally high but fluctuating concentrations of N and P in runoff water. Forestry and agricultural practices were major determinants of N runoff. Thehigh concentrations of both N and P in the major outlet of this watershed would be a major source of eutrophication for the recipient fjord. For both watersheds, climatic fluctuations strongly affected annual runoff patterns of N. The fate of ammonium relative to nitrate andlong-term climatic changes with a possible mineralization of soil stores of organic N are unpredictable determinants to future effects ofN. [ABSTRACT FROM AUTHOR]
- Published
- 1997
13. Atmospheric deposition of nitrogen, sulfur and chloride in two watersheds located in southern Norway
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Torseth, K. and Semb, A.
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ATMOSPHERIC deposition , *NITROGEN - Abstract
The deposition of atmospheric pollutants in southern Norway is relatively high, and exceeds the critical load for acid deposition in sensitive ecosystems. While the effects of the sulfur deposition are relatively well known and documented, the fate and effects of oxidized and reduced nitrogen compounds are much less well known. In order to study the cycling of nitrogen in southern Norway, the inter-institutional research program, Nitrogen from Mountains to Fjords, was launched in 1991. The program aims to describe the nitrogen mass balance and the effects of nitrogen deposition in two different watersheds in southern Norway. In this respect, quantification of the atmospheric inputfor comparison with runoff and other transfer data has been an important task. The atmospheric input has been estimated on the basis of available data from the national monitoring of air and precipitation chemistry, and additional measurement activities within the study areas, for the period 1993--1995. In the Bjerkreim watershed topographical effects result in large variation in precipitation amounts within the study area, and between the individual 44 hydrological subcatchments. Annual nitrogen deposition varied between 1400 and 2300 mg N m-2 yr-1, with the highest figures obtained for themountainous areas receiving most precipitation. Similar observationswere made for the atmospheric deposition of sulfur and chloride, which were determined in order to compare input and runoff data as well as a basis for calculation of exceedances of the critical loads. Annual deposition of sulfur and chloride were 900--1500 mg S m- 2 yr-1 and 12 000--21 000 mg Cl- m-2 yr-1. The Auli watershed shows much less variation in the amount of precipitation and, consequently, in the deposition of nitrogen, sulfur and chloride to the 12 subcatchments for which input data were estimated. Annual average deposition of nitrogen was estimated [ABSTRACT FROM AUTHOR]
- Published
- 1997
14. Behaviour of sulphur and nitrogen compounds measured at marine stations Lista and Saby in Scandinavia
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Torseth, K., Pacyna, J. M., Lindgren, E. A. Selin, Isakson, J., and Foltescu, V. L.
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NITROGEN ,POLLUTION ,SULFUR ,ZINC - Published
- 1995
15. Sulphur and nitrogen deposition in Norway, status and trends
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Semb, A. and Torseth, K.
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NITROGEN ,ACID deposition ,SULFUR - Published
- 1995
16. Extreme acidification in small catchments in southwestern Norway associated with a sea salt episode
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Torseth, K., Kaste, O., Hindar, A., and Henriksen, A.
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- 1995
17. Deposition of nitrogen and other major inorganic compounds in Norway, 1992-1996
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Semb, A. and Torseth, K.
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CALCIUM ,SODIUM ,POTASSIUM ,MAGNESIUM ,AIR pollution ,ACID precipitation (Meteorology) ,NITROGEN compounds - Abstract
Representative measurements of air and precipitation chemistry have been used to estimate atmospheric deposition for the period 1992-1996. In coastal areas of SW Norway, large precipitation amounts with high concentrations of nitrate and ammonium resulted in annual nitrogen (N) inputs of more than 2 g m
-2 year-1 (20 kg ha-1 year-1 ). Dry deposition is relatively unimportant in the areas with high precipitation intensities, whereas in some areas with less precipitation, forested areas may receive up to 30-50% of the total deposition in the form of dry deposition. Inputs of dry deposition to non-forested areas are much smaller, particularlyduring the period of snow cover. Comparison with similar estimates for the periods 1983-1987 and 1988-92 show that there has been a decrease in the deposition of reduced N, by 2% and 14%, and in the deposition of oxidized N, by 6% and by 23%, relative to the two periods. Thetrend for oxidized N is somewhat smaller than expected based on reported emission reductions in Northern Europe. Changes in the emission rates from off-shore activities in the North Sea may partly explain the observed discrepancies. For ammonium, the trend may be influenced by both reduced emissions and by the reductions of sulfur dioxide andnitrogen oxides, which may have reduced the rate of conversion from ammonia to ammonium aerosol, thereby decreasing the atmospheric residence time and the transport across the North Sea. Inter annual variations in the meteorological conditions may also have influenced the amounts of deposition. [ABSTRACT FROM AUTHOR]- Published
- 1998
18. Crown condition of Norway spruce in relation to sulphur and nitrogendeposition and soil properties in southeast Norway
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Solberg, S. and Torseth, K.
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ACID deposition ,FORESTS & forestry - Abstract
Atmospheric deposition of sulphur and nitrogen com pounds may lead to enhanced leaching of base cations, accumulation of nitrogen in organic matter, lowered pH and increased concentration of toxic aluminiumin soil, which in turn may affect the vitality of forest trees. A general monitoring of forest condition has been initiated in many European countries, partly in order to reveal stresses caused by acidification. However, forest condition is also affected by many other factors. This paper examines a seven-year series of crown-condition data from Local County Monitoring Plots in Norway spruce stands in Norway. Average, time trend and lability variables were calculated for crown density and crown colour for each plot. Wet deposition of sulphate, ammonium and nitrate for each plot were estimated using data from the national air and precipitation monitoring programmes. Soil data are based on soil sampling within the plots. The analysis gave no evident support for the hypothesized negative effect on crown condition from sulphur and nitrogen deposition and related alterations in soil. [ABSTRACT FROM AUTHOR]
- Published
- 1997
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19. Particle number size distribution in the eastern Mediterranean: Formation and growth rates of ultrafine airborne atmospheric particles.
- Author
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Kopanakis, I., Chatoutsidou, S.E., Torseth, K., Glytsos, T., and Lazaridis, M.
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PARTICLE size distribution , *GROWTH rate , *ATMOSPHERIC aerosols , *METEOROLOGICAL stations , *AIR masses , *ATMOSPHERIC nucleation - Abstract
Abstract: Particle number concentration was measured between June 2009 and June 2010 at Akrotiri research station in a rural/suburban region of western Crete (Greece). Overall, the available data covered 157 days during the aforementioned period of measurements. The objectives were to study the number size distribution characteristics of ambient aerosols and furthermore to identify new particle formation events and to evaluate particle formation rates and growth rates of the newborn particles. Aerosol particles with mobility diameters between 10 and 1100 nm were measured using a Scanning Mobility Particle Sizer (SMPS) system. Measurements were performed at ambient relative humidities. The median total particle number concentration was 525 #/cm3 whereas the number concentration ranged between 130 #/cm3 and 9597 #/cm3. The average percentage of particles with diameters between 10 nm and 100 nm (N10–100) to total particles was 53% during summer and spring, but reached 80% during winter. Maximum average contribution of nano-particles (10 nm < D p < 50 nm) to total particles was recorded also in winter and was attributed partly to the effect of local heating. Furthermore, back trajectories (HYSPLIT model) showed that different air mass origins are linked to different levels of particle number concentrations, with higher values associated with air masses passing from polluted areas before reaching the Akrotiri station. Modal analysis of the measured size distribution data revealed a strong nucleation mode during winter (15–25 nm), which can be correlated with emissions from local sources (domestic heating). The nucleation mode was observed also during the spring campaigns and was partly linked to new particle formation events. On the contrary, an accumulation mode (80–120 nm) prevailed in the measurements during summer campaigns, when the station area was influenced by polluted air masses arriving mainly from Eastern Europe. In total, 13 new particle formation events were recorded during the 157 days of measurements. Nucleation events were associated with low values of N100 particle number concentration and reduced coagulation sinks. Mean growth and formation rates were calculated and showed values equal to 6 nm hr−1 and 13 cm−3 s−1, respectively. [Copyright &y& Elsevier]
- Published
- 2013
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20. Measuring atmospheric composition change
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Laj, P., Klausen, J., Bilde, M., Plaß-Duelmer, C., Pappalardo, G., Clerbaux, C., Baltensperger, U., Hjorth, J., Simpson, D., Reimann, S., Coheur, P.-F., Richter, A., De Mazière, M., Rudich, Y., McFiggans, G., Torseth, K., Wiedensohler, A., Morin, S., Schulz, M., and Allan, J.D.
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CLIMATE change , *ATMOSPHERE , *AIR quality , *ATMOSPHERIC research , *REMOTE sensing , *SCIENTIFIC observation , *GLOBAL warming , *MATHEMATICAL models , *NUMERICAL analysis - Abstract
Abstract: Scientific findings from the last decades have clearly highlighted the need for a more comprehensive approach to atmospheric change processes. In fact, observation of atmospheric composition variables has been an important activity of atmospheric research that has developed instrumental tools (advanced analytical techniques) and platforms (instrumented passenger aircrafts, ground-based in situ and remote sensing stations, earth observation satellite instruments) providing essential information on the composition of the atmosphere. The variability of the atmospheric system and the extreme complexity of the atmospheric cycles for short-lived gaseous and aerosol species have led to the development of complex models to interpret observations, test our theoretical understanding of atmospheric chemistry and predict future atmospheric composition. The validation of numerical models requires accurate information concerning the variability of atmospheric composition for targeted species via comparison with observations and measurements. In this paper, we provide an overview of recent advances in instrumentation and methodologies for measuring atmospheric composition changes from space, aircraft and the surface as well as recent improvements in laboratory techniques that permitted scientific advance in the field of atmospheric chemistry. Emphasis is given to the most promising and innovative technologies that will become operational in the near future to improve knowledge of atmospheric composition. Our current observation capacity, however, is not satisfactory to understand and predict future atmospheric composition changes, in relation to predicted climate warming. Based on the limitation of the current European observing system, we address the major gaps in a second part of the paper to explain why further developments in current observation strategies are still needed to strengthen and optimise an observing system not only capable of responding to the requirements of atmospheric services but also to newly open scientific questions. [Copyright &y& Elsevier]
- Published
- 2009
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21. Number Concentration and Modal Structure of Indoor/Outdoor Fine Particles in Four European Cities
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Lazaridis, M., Eleftheriadis, K., Ždímal, Vladimír, Schwarz, Jaroslav, Wagner, Zdeněk, Ondráček, Jakub, Drossinos, Y., Glytsos, T., Vratolis, S., Torseth, K., and Smolík, Jiří
- Subjects
indoor number concentration ,indoor sources ,modal structure - Abstract
Indoor/outdoor measurements campaigns were performed in naturally ventilated houses and offices in four European cities to investigate the relationship between indoor and outdoor particle number concentrations and aerosol modal structures. The measurements sites were located in Oslo (Norway), Prague (Czech Republic), Milan (Italy) and Athens (Greece). A number of ordinary indoor activities (cooking, smoking, candle burning, etc.) were performed during the measurements to quantify the contribution of particles emitted from indoor sources and the contribution of outdoor particles to the change of the indoor aerosol size spectra.
- Published
- 2013
22. Immunohistochemical characterization of brain-invasive meningiomas.
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Backer-Grøndahl T, Moen BH, Arnli MB, Torseth K, and Torp SH
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- Biopsy, Cell Adhesion, Cell Proliferation, Female, Humans, Male, Meningeal Neoplasms mortality, Meningeal Neoplasms pathology, Meningeal Neoplasms therapy, Meningioma mortality, Meningioma pathology, Meningioma therapy, Neoplasm Invasiveness, Predictive Value of Tests, Treatment Outcome, Biomarkers, Tumor analysis, Immunohistochemistry, Matrix Metalloproteinase 9 analysis, Meningeal Neoplasms chemistry, Meningioma chemistry
- Abstract
Brain-invasive meningiomas have an adverse prognosis, so it is important to detect and correctly evaluate brain invasion by light microscopy. Furthermore, the underlying biological mechanisms responsible for brain-invasive growth are incompletely understood. The primary aim of this study was to identify immunohistochemical markers that could improve identification and evaluation of brain invasion in meningiomas. A second aim was to investigate the process of brain invasion using immunohistochemical markers of proliferation, extracellular matrix modulation, and cell adhesion. From a series of 196 human meningiomas, 67 cases were selected for analysis because of the presence of brain tissue in tumor specimens. Fourteen of these 67 meningiomas were brain-invasive. Invasiveness was determined primarily by evaluation of hematoxylin-erytrosin-saffron- (HES-) stained specimens, although glial fibrillary acidic protein (GFAP), anti-collagen IV, and cluster of differentiation 44 (CD44) markers provided additional information. It was important to examine microscopic sections from various levels of the paraffin-embedded tissue block to adequately assess invasiveness. Sections stained using antibodies against Ki-67/MIB-1, phospohistone-H3 (PHH3), matrix metalloproteinase-9 (MMP-9), cathepsin D, plasminogen activator inhibitor-1 (PAI-1), and E-cadherin antigens were used to characterize brain-invasive meningiomas and to investigate the process of brain invasion. Only increased expression of the extracellular matrix modulator MMP-9 correlated with brain-invasive growth (p=0.025). Examination of HES-stained sections identified brain invasion. Use of relevant immunohistochemical markers did not contribute substantially to this evaluation. Evaluation of stepwise sections should be considered when brain-invasive growth is suspected. MMP-9 may be an important mediator of brain-invasive growth.
- Published
- 2014
23. A combined nuclear and nucleolar localization motif in activation-induced cytidine deaminase (AID) controls immunoglobulin class switching.
- Author
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Hu Y, Ericsson I, Torseth K, Methot SP, Sundheim O, Liabakk NB, Slupphaug G, Di Noia JM, Krokan HE, and Kavli B
- Subjects
- Apoptosis Regulatory Proteins metabolism, Blotting, Western, Bone Neoplasms enzymology, Bone Neoplasms pathology, Cell Nucleolus genetics, Cells, Cultured, Cytidine Deaminase chemistry, Cytidine Deaminase genetics, Deamination, Fluorescent Antibody Technique, Glutathione Transferase genetics, Glutathione Transferase metabolism, HeLa Cells, Humans, Immunoenzyme Techniques, Immunoprecipitation, Kidney cytology, Kidney enzymology, Mutation genetics, Nuclear Proteins metabolism, Nucleophosmin, Osteosarcoma enzymology, Osteosarcoma pathology, Phosphoproteins metabolism, Protein Conformation, RNA-Binding Proteins metabolism, Recombination, Genetic, Nucleolin, Cell Nucleolus metabolism, Cytidine Deaminase metabolism, DNA metabolism, Immunoglobulin Class Switching physiology, Nuclear Localization Signals, Somatic Hypermutation, Immunoglobulin genetics
- Abstract
Activation-induced cytidine deaminase (AID) is a DNA mutator enzyme essential for adaptive immunity. AID initiates somatic hypermutation and class switch recombination (CSR) by deaminating cytosine to uracil in specific immunoglobulin (Ig) gene regions. However, other loci, including cancer-related genes, are also targeted. Thus, tight regulation of AID is crucial to balance immunity versus disease such as cancer. AID is regulated by several mechanisms including nucleocytoplasmic shuttling. Here we have studied nuclear import kinetics and subnuclear trafficking of AID in live cells and characterized in detail its nuclear localization signal. Importantly, we find that the nuclear localization signal motif also directs AID to nucleoli where it colocalizes with its interaction partner, catenin-β-like 1 (CTNNBL1), and physically associates with nucleolin and nucleophosmin. Moreover, we demonstrate that release of AID from nucleoli is dependent on its C-terminal motif. Finally, we find that CSR efficiency correlates strongly with the arithmetic product of AID nuclear import rate and DNA deamination activity. Our findings suggest that directional nucleolar transit is important for the physiological function of AID and demonstrate that nuclear/nucleolar import and DNA cytosine deamination together define the biological activity of AID. This is the first study on subnuclear trafficking of AID and demonstrates a new level in its complex regulation. In addition, our results resolve the problem related to dissociation of deamination activity and CSR activity of AID mutants., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2013
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24. The UNG2 Arg88Cys variant abrogates RPA-mediated recruitment of UNG2 to single-stranded DNA.
- Author
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Torseth K, Doseth B, Hagen L, Olaisen C, Liabakk NB, Græsmann H, Durandy A, Otterlei M, Krokan HE, Kavli B, and Slupphaug G
- Subjects
- Amino Acid Sequence, Amino Acid Substitution, Binding Sites genetics, Blotting, Western, Cell Line, Cell Line, Tumor, DNA Glycosylases chemistry, DNA Glycosylases genetics, DNA Replication genetics, DNA, Single-Stranded genetics, Humans, Immunoprecipitation, Luminescent Proteins genetics, Luminescent Proteins metabolism, Microscopy, Confocal, Molecular Sequence Data, Proliferating Cell Nuclear Antigen genetics, Proliferating Cell Nuclear Antigen metabolism, Protein Binding, Replication Protein A chemistry, Replication Protein A genetics, S Phase genetics, Sequence Homology, Amino Acid, DNA Glycosylases metabolism, DNA Repair, DNA, Single-Stranded metabolism, Mutation, Replication Protein A metabolism
- Abstract
In human cell nuclei, UNG2 is the major uracil-DNA glycosylase initiating DNA base excision repair of uracil. In activated B cells it has an additional role in facilitating mutagenic processing of AID-induced uracil at Ig loci and UNG-deficient patients develop hyper-IgM syndrome characterized by impaired class-switch recombination and disturbed somatic hypermutation. How UNG2 is recruited to either error-free or mutagenic uracil processing remains obscure, but likely involves regulated interactions with other proteins. The UNG2 N-terminal domain contains binding motifs for both proliferating cell nuclear antigen (PCNA) and replication protein A (RPA), but the relative contribution of these interactions to genomic uracil processing is not understood. Interestingly, a heterozygous germline single-nucleotide variant leading to Arg88Cys (R88C) substitution in the RPA-interaction motif of UNG2 has been observed in humans, but with unknown functional relevance. Here we demonstrate that UNG2-R88C protein is expressed from the variant allele in a lymphoblastoid cell line derived from a heterozygous germ line carrier. Enzyme activity as well as localization in replication foci of UNG2-R88C was similar to that of WT. However, binding to RPA was essentially abolished by the R88C substitution, whereas binding to PCNA was unaffected. Moreover, we show that disruption of the PCNA-binding motif impaired recruitment of UNG2 to S-phase replication foci, demonstrating that PCNA is a major factor for recruitment of UNG2 to unperturbed replication forks. Conversely, in cells treated with hydroxyurea, RPA mediated recruitment of UNG2 to stalled replication forks independently of functional PCNA binding. Modulation of PCNA- versus RPA-binding may thus constitute a functional switch for UNG2 in cells subsequent to genotoxic stress and potentially also during the processing of uracil at the immunoglobulin locus in antigen-stimulated B cells., (Copyright © 2012 Elsevier B.V. All rights reserved.)
- Published
- 2012
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25. The region of XRCC1 which harbours the three most common nonsynonymous polymorphic variants, is essential for the scaffolding function of XRCC1.
- Author
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Hanssen-Bauer A, Solvang-Garten K, Gilljam KM, Torseth K, Wilson DM 3rd, Akbari M, and Otterlei M
- Subjects
- Animals, CHO Cells, Cricetinae, Cricetulus, DNA Damage, DNA Polymerase beta metabolism, DNA Repair drug effects, DNA Repair genetics, DNA Repair radiation effects, DNA Repair Enzymes metabolism, DNA Replication drug effects, DNA Replication genetics, DNA Replication radiation effects, DNA-Binding Proteins genetics, Humans, Methyl Methanesulfonate pharmacology, Nuclear Localization Signals, Phosphotransferases (Alcohol Group Acceptor) metabolism, Proliferating Cell Nuclear Antigen metabolism, Protein Structure, Tertiary, Protein Transport drug effects, Protein Transport radiation effects, X-ray Repair Cross Complementing Protein 1, DNA-Binding Proteins chemistry, DNA-Binding Proteins metabolism, Polymorphism, Single Nucleotide
- Abstract
XRCC1 functions as a non-enzymatic, scaffold protein in single strand break repair (SSBR) and base excision repair (BER). Here, we examine different regions of XRCC1 for their contribution to the scaffolding functions of the protein. We found that the central BRCT1 domain is essential for recruitment of XRCC1 to sites of DNA damage and DNA replication. Also, we found that ectopic expression of the region from residue 166-436 partially rescued the methyl methanesulfonate (MMS) hypersensitivity of XRCC1-deficient EM9 cells, suggesting a key role for this region in mediating DNA repair. The three most common amino acid variants of XRCC1, Arg194Trp, Arg280His and Arg399Gln, are located within the region comprising the NLS and BRCT1 domains, and these variants may be associated with increased incidence of specific types of cancer. While we could not detect differences in the intra-nuclear localization or the ability to support recruitment of POLβ or PNKP to micro-irradiated sites for these variants relative to the conservative protein, we did observe lower foci intensity after micro-irradiation and a reduced stability of the foci with the Arg280His and Arg399Gln variants, respectively. Furthermore, when challenged with MMS or hydrogen peroxide, we detected small but consistent differences in the repair profiles of cells expressing these two variants in comparison to the conservative protein., (Copyright © 2012 Elsevier B.V. All rights reserved.)
- Published
- 2012
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26. Assessing PM10 source reduction in urban agglomerations for air quality compliance.
- Author
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Aleksandropoulou V, Eleftheriadis K, Diapouli E, Torseth K, and Lazaridis M
- Subjects
- Air Pollution legislation & jurisprudence, Air Pollution prevention & control, Cities, Environmental Monitoring, Environmental Policy, Greece, Particle Size, Air Pollutants analysis, Air Pollution statistics & numerical data, Particulate Matter analysis
- Abstract
The objective of this work was to study PM(10) and PM(2.5) concentration data available from monitoring stations in two large urban agglomerations in Greece and to estimate the emissions reduction required for compliance with the EU Air Quality Standards (AQS) for particulate matter. The cities studied are namely the Athens and Thessaloniki Metropolitan Areas (AMA and TMA, respectively). PM(10) concentrations during the period 2001-2010 have been evaluated for 15 air quality monitoring stations in the two urban areas. It was found that the concentrations of PM(10) during the period studied constantly exceeded the threshold values at the traffic and industrial stations in TMA and most of the traffic sites in AMA. Most of the occurrences of non-attainment to the daily AQSs were observed during the winter period at all stations (more pronounced for TMA stations). The reduction in current emission source strength to meet the air quality goal was calculated by the rollback equation using PM(10) day-averaged concentrations over the selected period at each station. Among the lognormal and Weibull distributions, the lognormal distribution was found to best fit the frequency distributions of PM(10) concentrations at the selected stations. The results showed that the minimum reduction required in order to meet the AQS in the AMA ranges from approximately 20 to 38% and up to 11% for traffic and background stations, respectively. Reductions in the range of 31% for traffic and 44% for industrial areas in TMA are also required. The same methodology was applied to PM(2.5) concentrations in the AMA and showed that emission reductions up to 31% are necessary in order to meet the 2020 EU AQS. Finally, continuous concentration data of organic (OC) and elementary carbon (EC) in PM(2.5) were used to study the possibility of achieving specific emission attenuation objectives in AMA.
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- 2012
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27. Cell cycle-specific UNG2 phosphorylations regulate protein turnover, activity and association with RPA.
- Author
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Hagen L, Kavli B, Sousa MM, Torseth K, Liabakk NB, Sundheim O, Pena-Diaz J, Otterlei M, Hørning O, Jensen ON, Krokan HE, and Slupphaug G
- Subjects
- Amino Acid Sequence, Animals, Catalysis, Cattle, DNA Glycosylases chemistry, DNA Glycosylases genetics, HeLa Cells, Humans, Mice, Molecular Sequence Data, Phosphoproteins chemistry, Phosphoproteins genetics, Phosphoproteins metabolism, Phosphorylation, Protein Isoforms chemistry, Protein Isoforms genetics, Protein Isoforms metabolism, Replication Protein A physiology, Serine metabolism, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Threonine metabolism, Uracil metabolism, Cell Cycle physiology, DNA Glycosylases metabolism, Replication Protein A metabolism
- Abstract
Human UNG2 is a multifunctional glycosylase that removes uracil near replication forks and in non-replicating DNA, and is important for affinity maturation of antibodies in B cells. How these diverse functions are regulated remains obscure. Here, we report three new phosphoforms of the non-catalytic domain that confer distinct functional properties to UNG2. These are apparently generated by cyclin-dependent kinases through stepwise phosphorylation of S23, T60 and S64 in the cell cycle. Phosphorylation of S23 in late G1/early S confers increased association with replication protein A (RPA) and replicating chromatin and markedly increases the catalytic turnover of UNG2. Conversely, progressive phosphorylation of T60 and S64 throughout S phase mediates reduced binding to RPA and flag UNG2 for breakdown in G2 by forming a cyclin E/c-myc-like phosphodegron. The enhanced catalytic turnover of UNG2 p-S23 likely optimises the protein to excise uracil along with rapidly moving replication forks. Our findings may aid further studies of how UNG2 initiates mutagenic rather than repair processing of activation-induced deaminase-generated uracil at Ig loci in B cells.
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- 2008
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28. Requirements for developing a regional monitoring capacity for aerosols in Europe within EMEP.
- Author
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Kahnert M, Lazaridis M, Tsyro S, and Torseth K
- Subjects
- Atmosphere chemistry, Environment, Europe, Humans, International Cooperation, Particle Size, Public Health, Aerosols analysis, Air Pollutants analysis, Environmental Monitoring
- Abstract
The European Monitoring and Evaluation Programme (EMEP) has been established to provide information to Parties to the Convention on Long Range Transboundary Air Pollution on deposition and concentration of air pollutants, as well as on the quantity and significance of long-range transmission of pollutants and transboundary fluxes. To achieve its objectives with the required scientific credibility and technical underpinning, a close integration of the programme's main elements is performed. These elements are emission inventories, chemical transport modelling, and the monitoring of atmospheric chemistry and deposition fluxes, which further are integrated towards abatement policy development. A critical element is the air pollution monitoring that is performed across Europe with a focus not only on health effect aspects and compliance monitoring, but also on process studies and source receptor relationships. Without a strong observational basis a predictive modelling capacity cannot be developed and validated. Thus the modelling success strongly depends on the quality and quantity of available observations. Particulate matter (PM) is a relatively recent addition to the EMEP monitoring programme, and the network for PM mass observations is still evolving. This article presents the current status of EMEP aerosol observations, followed by a critical evaluation in view of EMEP's main objectives and its model development requirements. Specific recommendations are given for improving the PM monitoring programme within EMEP.
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- 2004
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29. Temporal and spatial variations of airborne Mg, Cl, Na, Ca and K in rural areas of Norway
- Author
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Torseth K, Hanssen JE, and Semb A
- Abstract
The Norwegian air chemistry monitoring network includes measurements of gaseous and particulate compounds in air at 12 rural sites. The sampling method is designed to determine concentration levels of sulphur and nitrogen compounds and uses a three-stage filter pack sampler. Concentration levels of base-cations and sea salts may also be determined from the chemical analysis of the filter extracts. In this study, concentration levels of water soluble Mg, Cl, Na, Ca and K in air have been investigated in terms of temporal, seasonal and spatial trends during the period 1986-1996. The results have been combined with precipitation chemistry data to estimate total deposition, and to evaluate the relative importance of dry deposition. While Na, Cl and Mg are of marine origin, which is clearly reflected in concentration ratios and spatial gradients, Ca and K are of a mixed origin. Air trajectory analyses indicate that air masses originating in Eastern Europe result in significantly higher airborne concentrations of non-sea salt Ca and K, than air from other sectors. Major sources of airborne Ca and K in Norway are expected to be of anthropogenic origin from combustion plants and industrial processes in Eastern Europe, while aeolian dust from agricultural areas within Europe or from Sahara is of limited importance. Concentration levels of non-sea salt base-cations in air were 20-30% lower during the 1990s, compared to 1986-1989. Precipitation chemistry data available since the early 1980s indicate even larger reductions, and in the order of 50%. Total deposition of non-sea salt base-cations during 1993-1996 was generally below 10 mmol(c) m-2 year-1, whereas in coastal areas with large precipitation amounts, inputs exceeding 15 mmol(c) m-2 year-1 occurred. Deposition of base-cations may thus counteract up to 25% of the strong acid anion input, but more typically in the order of 5-10%. Dry deposition of non-sea salt base-cations of southern Norway is comparatively small, typically contributing 10-30% to the total deposition in the inland areas, and relatively less in other regions.
- Published
- 1999
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