... Food Additives and Contaminants 20(6), 607– 618. Aurela B., Kulmala, H.; Soderhjelm, L. 1999. Phthalates in ... Food Additives and Contaminants 16 (12), 571– 577. Aurela, B.; Ohra-aho T., Söderhjelm L., 2001. Migration ...
Tópico(s): Microplastics and Plastic Pollution
2011 - European Food Safety Authority | EFSA Supporting Publications
Anna Frey, Jarkko Tissari, Karri Saarnio, Hilkka Timonen, O. Tolonen-Kivimäki, Minna Aurela, Sanna Saarikoski, Ulla Makkonen, Kati Hytönen, Jorma Jokiniemi, Raimo O. Salonen, Risto Hillamo,
Residential wood combustion is a significant particulate emission source in many European countries. Especially for fine particle emissions in wood combustions, the lacking knowledge of emission factors (F E ) makes assessment of their contribution to ambient concentrations difficult. One reason for the discrepancy between modeled and measured contributions is many variables involved in combustion process. In this study, the fine particulate matter (PM) emissions coming from batch combustion of birch ...
Tópico(s): Fire dynamics and safety research
2009 - | Boreal environment research
Tea Thum, Tuula Aalto, Tuomas Laurila, Mika Aurela, Juha Hatakka, Anders Lindroth, Timo Vesala,
We studied the commencement and finishing of the growing season using different air temperature indices, the surface albedo, the chlorophyll fluorescence (Fv/Fm) and the carbon dioxide (CO2) tropospheric concentration, together with eddy covariance measurements of CO2 flux. We used CO2 flux data from four boreal coniferous forest sites covering a wide latitudinal range, and CO2 concentration measurements from Sammaltunturi in Pallas. The CO2 gas exchange was taken as the primary determinant for the ...
Tópico(s): Plant Water Relations and Carbon Dynamics
2009 - Taylor & Francis | Tellus B
Mika Aurela, Annalea Lohila, Juha‐Pekka Tuovinen, Juha Hatakka, Tuomas Laurila, Terhi Riutta,
Long-term net ecosystem CO{sub 2} exchange measurements were conducted on a nutrient-rich fen in northern Finland using the eddy covariance method. During the three measurement years (2006-2008), the mean daytime CO{sub 2} flux in July was -0.40 mg CO{sub 2} m-2 s-1, while in mid-winter (January-March) the mean efflux was 0.008 mg CO{sub 2} m-2 s-1. Annual balances of -12, -123 and -216 g CO{sub 2} m-2 a-1 were observed in 2006, 2007 and 2008, respectively. It is suggested that the low uptake in 2006 ...
Tópico(s): Plant Water Relations and Carbon Dynamics
2009 - | Boreal environment research
Magnus Lund, Peter M. Lafleur, Nigel T. Roulet, Anders Lindroth, Torben R. Christensen, Mika Aurela, Bogdan H. Chojnicki, Lawrence B. Flanagan, Elyn Humphreys, Tuomas Laurila, Walter C. Oechel, Janusz Olejnik, Janne Rinne, Per Schubert, Mats B. Nilsson,
Abstract Many wetland ecosystems such as peatlands and wet tundra hold large amounts of organic carbon (C) in their soils, and are thus important in the terrestrial C cycle. We have synthesized data on the carbon dioxide (CO 2 ) exchange obtained from eddy covariance measurements from 12 wetland sites, covering 1–7 years at each site, across Europe and North America, ranging from ombrotrophic and minerotrophic peatlands to wet tundra ecosystems, spanning temperate to arctic climate zones. The average ...
Tópico(s): Climate variability and models
2009 - Wiley | Global Change Biology
Remko A. Duursma, Pasi Kolari, Martti Perämäki, Marjo Pulkkinen, Annikki Mäkelä, Eero Nikinmaa, P. Hari, Mika Aurela, Paul Berbigier, Christian Bernhofer, Thomas Grünwald, Denis Loustau, Meelis Mölder, Hans Verbeeck, Timo Vesala,
Gross primary production (GPP) is the primary source of all carbon fluxes in the ecosystem. Understanding variation in this flux is vital to understanding variation in the carbon sink of forest ecosystems, and this would serve as input to forest production models. Using GPP derived from eddy-covariance (EC) measurements, it is now possible to determine the most important factor to scale GPP across sites. We use long-term EC measurements for six coniferous forest stands in Europe, for a total of 25 ...
Tópico(s): Plant responses to elevated CO2
2009 - Oxford University Press | Tree Physiology
Birgit Aurela, Jukka A. Ketoja,
Abstract Predictive migration models for polymers are already so well established that the European Commission intends to allow the use of the models as one quality assurance tool in product safety assessment of plastic materials and articles for food contact. The inhomogeneity of fibre-based materials makes modelling difficult--thus, little research has been done in this area. The authors compare experiments on the diffusion of certain volatile compounds through laboratory kraft pulp sheets with ...
Tópico(s): Material Properties and Processing
2002 - Taylor & Francis | Food Additives & Contaminants
Mika Aurela, Tuomas Laurila, Juha‐Pekka Tuovinen,
The annual balance of CO 2 was measured on a subarctic flark fen located in northern Finland (69°08′N, 27°17′E). Measurements were conducted using the micrometeorological eddy covariance method during the period from April 1998 to April 1999. Special emphasis was put on the importance of the wintertime CO 2 balance as a component of the annual budget. The CO 2 fluxes observed during the winter were relatively small (0.0055 mg CO 2 m −2 s −1 ), but due to the long duration of the snow cover period, they ...
Tópico(s): Geology and Paleoclimatology Research
2002 - American Geophysical Union | Journal of Geophysical Research Atmospheres
Juha Heikkinen, Marja Maljanen, Mika Aurela, K.J. Hargreaves, Pertti J. Martikainen,
We studied carbon dynamics on various surface parts of a highly patterned fen, typical in northern Finland, to examine the importance of different microsites to the areal carbon fluxes. The studies were carried out in June-September 1995 on a mesotrophic flark fen (an aapa mire) in Kaamanen (69°08?N, 27° 17?E). Wet flarks, moist lawns and dry strings accounted for 60%, 10% and 30% of the surface area, respectively. A static chamber technique was applied to measure the CH4 exchange, the instantaneous ...
Tópico(s): Science and Climate Studies
2002 - Wiley | Polar Research
Juha Heikkinen, Marja Maljanen, Mika Aurela, K.J. Hargreaves, Pertti J. Martikainen,
We studied carbon dynamics on various surface parts of a highly patterned fen, typical in northern Finland, to examine the importance of different microsites to the areal carbon fluxes. The studies were carried out in June-September 1995 on a mesotrophic flark fen (an aapa mire) in Kaamanen (69°08?N, 27° 17?E). Wet flarks, moist lawns and dry strings accounted for 60%, 10% and 30% of the surface area, respectively. A static chamber technique was applied to measure the CH4 exchange, the instantaneous ...
Tópico(s): Coastal wetland ecosystem dynamics
2002 - Wiley | Polar Research
Tuula Aalto, Juha Hatakka, Jussi Paatero, Juha‐Pekka Tuovinen, Mika Aurela, Tuomas Laurila, Kim Holmén, N. B. A. Trivett, Y. Viisanen,
Diurnal and annual variations of CO2, O3, SO2, black carbon and condensation nuclei and their source areas were studied by utilizing air parcel trajectories and tropospheric concentration measurements at a boreal GAW site in Pallas, Finland. The average growth trend of CO2 was about 2.5 ppm yr−1 according to a 4-yr measurement period starting in October 1996. The annual cycle of CO2 showed concentration difference of about 19 ppm between the summer minimum and winter maximum. The diurnal cycle was ...
Tópico(s): Atmospheric Ozone and Climate
2002 - Taylor & Francis | Tellus B
Tanja Suni, Frank Berninger, Timo Vesala, Tiina Markkanen, Pertti Hari, Annikki Mäkelä, Hannu Ilvesniemi, Heikki Hänninen, Eero Nikinmaa, Timo Huttula, Tuomas Laurila, Mika Aurela, Achim Grelle, Anders Lindroth, Almut Arneth, Olga Shibistova, Jon Lloyd,
Abstract The timing of the commencement of photosynthesis ( P * ) in spring is an important determinant of growing‐season length and thus of the productivity of boreal forests. Although controlled experiments have shed light on environmental mechanisms triggering release from photoinhibition after winter, quantitative research for trees growing naturally in the field is scarce. In this study, we investigated the environmental cues initiating the spring recovery of boreal coniferous forest ecosystems under ...
Tópico(s): Ecology and Vegetation Dynamics Studies
2003 - Wiley | Global Change Biology
Tea Thum, Tuula Aalto, Tuomas Laurila, Mika Aurela, Anders Lindroth, Timo Vesala,
Abstract. The seasonality of the NEE of the northern boreal coniferous forests was investigated by means of inversion modelling using eddy covariance data. Eddy covariance data was used to optimize the biochemical model parameters. Our study sites consisted of three Scots pine (l. Pinus sylvestris) forests and one Norway spruce (l. Picea abies) forest that were located in Finland and Sweden. We obtained temperature and seasonal dependence for the biochemical model parameters: the maximum rate of carboxylation ( ...
Tópico(s): Plant responses to elevated CO2
2008 - Copernicus Publications | Biogeosciences
Hilkka Timonen, Sanna Saarikoski, Minna Aurela, Karri Saarnio, Risto Hillamo,
The aim of this study was to characterize the concentrations and particle mass size distributions of water-soluble organic carbon (WSOC) in urban aerosols. The sample collection was carried out in spring 2006 at the SMEAR III station in Helsinki, Finland, by using a size-segregating method (MOUDI) and by collecting sub-micrometer fraction of aerosols on the filter. During the three-month measurement period, a major 12-day biomass burning pollution episode was observed. Concentrations of WSOC, organic ...
Tópico(s): Vehicle emissions and performance
2008 - | Boreal environment research
Anders Lindroth, Fredrik Lagergren, Mika Aurela, Brynhildur Bjarnadóttir, Torben R. Christensen, Ebba Dellwik, Achim Grelle, Andreas Ibrom, Torbjörn Johansson, Harry Lankreijer, Samuli Launiainen, Tuomas Laurila, Meelis Mölder, Eero Nikinmaa, Kim Pilegaard, Bjarni D. Sigurðsson, Timo Vesala,
Tópico(s): Environmental Changes in China
2008 - Taylor & Francis | Tellus B
Anders Lindroth, Fredrik Lagergren, Mika Aurela, Brynhildur Bjarnadóttir, Torben R. Christensen, Ebba Dellwik, Achim Grelle, Andreas Ibrom, Torbjörn Johansson, Harry Lankreijer, Samuli Launiainen, Tuomas Laurila, Meelis Mölder, Eero Nikinmaa, Kim Pilegaard, Bjarni D. Sigurðsson, Timo Vesala,
Data on net CO 2 exchange from eight forests in Denmark, Sweden, Finland and Iceland were used to analyse which factors were controlling photosynthesis and respiration. The forests consisted of different species ranging in climatic condition from temperate to subarctic. Only well mixed conditions were analysed ( u * > 0.3 m s -1 ). The parameters of a light response function showed strong seasonal variations with similar behaviour for all stands except for a beech forest where the development of a vigorous ...
Tópico(s): Atmospheric and Environmental Gas Dynamics
2008 - Taylor & Francis | Tellus B
Mathias Göckede, Thomas Foken, Marc Aubinet, Minna Aurela, J. Banza, Christian Bernhofer, J. M. Bonnefond, Yves Brunet, Arnaud Carrara, R. Clement, Ebba Dellwik, J.A. Elbers, W. Eugster, Jürg Fuhrer, André Granier, Thomas Grünwald, Bernard Heinesch, Ivan A. Janssens, Alexander Knohl, Renate Koeble, T. Laurila, Bernard Longdoz, Giovanni Manca, Michal V. Marek, T. Markkanen, J. Mateus, Gioṙgio Matteucci, Matthias Mauder, Mirco Migliavacca, Stefano Minerbi, J. B. Moncrieff, Leonardo Montagnani, Eddy Moors, Jean‐Marc Ourcival, Dario Papale, J. S. Pereira, Kim Pilegaard, Gabriel Pita, Serge Rambal, Corinna Rebmann, Abel Rodrigues, Eyal Rotenberg, María José Sanz, Pavel Sedlák, G. Seufert, Lukas Siebicke, Jean‐François Soussana, Riccardo Valentini, Timo Vesala, Hans Verbeeck, Dan Yakir,
Abstract. We applied a site evaluation approach combining Lagrangian Stochastic footprint modeling with a quality assessment approach for eddy-covariance data to 25 forested sites of the CarboEurope-IP network. The analysis addresses the spatial representativeness of the flux measurements, instrumental effects on data quality, spatial patterns in the data quality, and the performance of the coordinate rotation method. Our findings demonstrate that application of a footprint filter could strengthen ...
Tópico(s): Tree-ring climate responses
2008 - Copernicus Publications | Biogeosciences
Jarkko V. Niemi, Sanna Saarikoski, Minna Aurela, Heikki Tervahattu, Risto Hillamo, Douglas L. Westphal, Päivi Aarnio, Tarja Koskentalo, Ulla Makkonen, Hanna Vehkamäki, Markku Kulmala,
The frequency, strength and sources of long-range transport (LRT) episodes of fine particles (PM2.5) were studied in southern Finland using air quality monitoring results, backward air mass trajectories, remote sensing of fire hot spots, transport and dispersion modelling of smoke and chemical analysis of particle samples (black carbon, monosaccharide anhydrides, oxalate, succinate, malonate, SO42−, NO3−, K+ and NH4+). At an urban background site in Helsinki, the daily WHO guideline value (24-h PM2. ...
Tópico(s): Energy and Environment Impacts
2008 - Elsevier BV | Atmospheric Environment
Hilkka Timonen, Sanna Saarikoski, O. Tolonen-Kivimäki, Minna Aurela, Karri Saarnio, Tuukka Petäjä, Tuula Aalto, Markku Kulmala, T. Pakkanen, Risto Hillamo,
Abstract. This paper represents the results of one year long measurement period of the size distributions of water-soluble organic carbon (WSOC), inorganic ions and gravimetric mass of particulate matter. Measurements were done at an urban background station (SMEAR III) by using a micro-orifice uniform deposit impactor (MOUDI). The site is located in northern European boreal region in Helsinki, Finland. The WSOC size distribution measurements were completed with the chemical analysis of inorganic ions, ...
Tópico(s): Atmospheric Ozone and Climate
2008 - Copernicus Publications | Atmospheric chemistry and physics
Aurela Shtiza, Rudy Swennen, Valérie Cappuyns, Artan Tashko,
Tópico(s): Environmental remediation with nanomaterials
2008 - Springer Nature | Environmental Geology
Sanna Saarikoski, Hilkka Timonen, Karri Saarnio, Minna Aurela, Leena Järvi, P. Keronen, Veli‐Matti Kerminen, Risto Hillamo,
Abstract. A major fraction of fine particle matter consists of organic carbon (OC) but its origin is still inadequately known. In this study the sources of OC were investigated in the northern European urban environment in Helsinki, Finland. Measurements were carried out over one year and they included both filter (PM1) and online methods. From the filter samples OC, elemental carbon (EC), water-soluble OC (WSOC), levoglucosan and major ions were analyzed. Filter data together with the concentrations ...
Tópico(s): Vehicle emissions and performance
2008 - Copernicus Publications | Atmospheric chemistry and physics
Hilkka Timonen, Minna Aurela, Samara Carbone, Karri Saarnio, Sanna Saarikoski, Tomi P. Mäkelä, Markku Kulmala, Veli‐Matti Kerminen, Douglas R. Worsnop, Risto Hillamo,
Abstract. A particle-into-liquid sampler (PILS) was coupled with a total organic carbon analyzer (TOC) and two ion chromatographs (IC) to enable high time-resolution measurements of water-soluble ions and water-soluble organic carbon (WSOC) by a single sampling and analytical set-up. The new high time-resolution measurement system, the PILS-TOC-IC, was able to provide essential chemical and physical information about fast changes in composition, concentrations and likely sources of the water-soluble ...
Tópico(s): Atmospheric Ozone and Climate
2010 - Copernicus Publications | Atmospheric measurement techniques
Eija Asmi, Anna Frey, Aki Virkkula, Mikael Ehn, Hanna E. Manninen, Hilkka Timonen, O. Tolonen-Kivimäki, Minna Aurela, Risto Hillamo, Markku Kulmala,
Abstract. The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements ...
Tópico(s): Air Quality and Health Impacts
2010 - Copernicus Publications | Atmospheric chemistry and physics
Annalea Lohila, Minna Aurela, Juha Hatakka, Mari Pihlatie, Kari Minkkinen, Timo Penttilä, Tuomas Laurila,
Nitrous oxide (N 2 O) fluxes were measured fortnightly to monthly with manual chambers in 2004–2008 and hourly with automatic chambers during the snow‐free seasons of 2007 and 2008 in a sedge fen in northern Finland. The fluxes were generally low, varying from −45 to 37 µg N 2 O–N m −2 hour −1 (negative fluxes indicating uptake of N 2 O from the atmosphere into the soil) and showing large spatial and temporal variation. Slightly higher emissions were observed in winter than in summer. On an annual scale, ...
Tópico(s): Soil Carbon and Nitrogen Dynamics
2010 - Wiley | European Journal of Soil Science
Minna Aurela, Sanna Saarikoski, Hilkka Timonen, Tuula Aalto, P. Keronen, Karri Saarnio, Kimmo Teinilä, Markku Kulmala, R. Hillamo,
Submicrometer organic carbon (OC) and elemental carbon (EC) concentrations were studied for one year (2007–2008) in Finland at an urban background site (Helsinki) and a forested site (Hyytiälä). Particles were collected on quartz filters that were analyzed by a thermal-optical carbon analyzer in the laboratory. Results were calculated by taking into account the positive sampling artefact and the optical correction for the pyrolysis during the analysis. Typically OC and EC concentrations were higher in ...
Tópico(s): Plant responses to elevated CO2
2010 - Elsevier BV | Atmospheric Environment
Liisa Maanavilja, Terhi Riutta, Mika Aurela, Minna Pulkkinen, Tuomas Laurila, Eeva‐Stiina Tuittila,
Tópico(s): Botany and Plant Ecology Studies
2010 - Springer Science+Business Media | Biogeochemistry
Guillermo Gea‐Izquierdo, Annikki Mäkelä, Hank A. Margolis, Yves Bergeron, T. Andrew Black, Allison L. Dunn, Julian L. Hadley, Kyaw Tha Paw U, M. Falk, Sonia Wharton, Russell K. Monson, David Y. Hollinger, Tuomas Laurila, Mika Aurela, Harry McCaughey, Charles P.‐A. Bourque, Timo Vesala, Frank Berninger,
• In this study, we used a canopy photosynthesis model which describes changes in photosynthetic capacity with slow temperature-dependent acclimations. • A flux-partitioning algorithm was applied to fit the photosynthesis model to net ecosystem exchange data for 12 evergreen coniferous forests from northern temperate and boreal regions. • The model accounted for much of the variation in photosynthetic production, with modeling efficiencies (mean > 67%) similar to those of more complex models. The parameter ...
Tópico(s): Tree-ring climate responses
2010 - Wiley | New Phytologist
Produção Nacional
Revisado por pares
Chuixiang Yi, D. M. Ricciuto, Runze Li, John Wolbeck, Xiyan Xu, Mats B. Nilsson, Luís Aires, J. D. Albertson, Christof Ammann, M. Altaf Arain, Alessandro Araújo, Marc Aubinet, Mika Aurela, Zoltán Barcza, Alan Barr, Paul Berbigier, Jason Beringer, Christian Bernhofer, T. Andrew Black, Paul V. Bolstad, Fred C. Bosveld, M. S. J. Broadmeadow, Nina Buchmann, Sean P. Burns, Pierre Cellier, Jingming Chen, Jiquan Chen, Philippe Ciais, Robert Clement, Bruce D. Cook, Peter S. Curtis, D. B. Dail, Ebba Dellwik, Nicolas Delpierre, Ankur R. Desai, Sabina Dore, D. Dragoni, Bert G. Drake, Éric Dufrêne, Allison L. Dunn, J.A. Elbers, Werner Eugster, M. Falk, Christian Feigenwinter, Lawrence B. Flanagan, Thomas Foken, J. M. Frank, J. Fuhrer, Damiano Gianelle, A. H. Goldstein, Mike Goulden, André Granier, Thomas Grünwald, Lianhong Gu, Haiqiang Guo, Albin Hammerle, Shijie Han, Niall P. Hanan, László Haszpra, Bernard Heinesch, Carole Helfter, Dimmie Hendriks, Lindsay B. Hutley, Andreas Ibrom, C.M.J. Jacobs, Torbjörn Johansson, Marjan Jongen, Gabriel G. Katul, Gerard Kiely, Katja Klumpp, Alexander Knohl, Thomas E. Kolb, Werner L. Kutsch, Peter M. Lafleur, Tuomas Laurila, R. Leuning, Anders Lindroth, Heping Liu, Benjamin Loubet, Giovanni Manca, Michal V. Marek, Hank A. Margolis, Timothy A. Martin, W. J. Massman, Roser Matamala, Gioṙgio Matteucci, Harry McCaughey, Lutz Merbold, Tilden Meyers, Mirco Migliavacca, F. Miglietta, Laurent Misson, Meelis Mölder, John Moncrieff, Russell K. Monson, Leonardo Montagnani, M. Montes‐Helu, Eddy Moors, Christine Moureaux, M. M. Mukelabai, J. William Munger, M. Myklebust, Zoltán Nagy, Asko Noormets, Walter C. Oechel, Ram Oren, Stephen G. Pallardy, K.T. Paw U, J. S. Pereira, Kim Pilegaard, Krisztina Pintér, Casimiro Pio, Gabriel Pita, Thomas L. Powell, Serge Rambal, James T. Randerson, Celso von Randow, Corinna Rebmann, Janne Rinne, Federica Rossi, Nigel T. Roulet, Ronald J. Ryel, Jörgen Sagerfors, Nobuko Saigusa, María José Sanz, G Scarascia Mugnozza, Hans Peter Schmid, G. Seufert, Mario Siqueira, Jean‐François Soussana, Gregory Starr, Mark A. Sutton, John Tenhunen, Zoltán Tuba, Juha‐Pekka Tuovinen, Riccardo Valentini, Christoph S. Vogel, Jingxin Wang, Shaoqiang Wang, Weiguo Wang, L. R. Welp, Xuefa Wen, Sonia Wharton, Matthew Wilkinson, C. A. Williams, Georg Wohlfahrt, Susumu Yamamoto, Guirui Yu, Roberto Zampedri, Bin Zhao, Xinquan Zhao,
Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate–carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate ...
Tópico(s): Climate variability and models
2010 - IOP Publishing | Environmental Research Letters
Karri Saarnio, Minna Aurela, Hilkka Timonen, Sanna Saarikoski, Kimmo Teinilä, Tomi P. Mäkelä, Mikhail Sofiev, J. Koskinen, Tuula Aalto, Markku Kulmala, Jaakko Kukkonen, Risto Hillamo,
A series of smoke plumes was detected in Helsinki, Finland, during a one-month-lasting period in August 2006. The smoke plumes originated from wildfires close to Finland, and they were short-term and had a high particulate matter (PM) concentration. Physical and chemical properties of fine particles in those smokes were characterised by a wide range of real-time measurements that enabled the examination of individual plume events. Concurrently PM1 filter samples were collected and analysed off-line. ...
Tópico(s): Atmospheric aerosols and clouds
2010 - Elsevier BV | The Science of The Total Environment
Karri Saarnio, Kimmo Teinilä, Minna Aurela, Hilkka Timonen, Risto Hillamo,
Tópico(s): Indoor Air Quality and Microbial Exposure
2010 - Springer Science+Business Media | Analytical and Bioanalytical Chemistry