Contribution of residential wood combustion to hourly winter aerosol in Northern Sweden determined by positive matrix factorization

International audienceThe combined effect of residential wood combustion (RWC) emissions with stable atmospheric conditions, which is a frequent occurrence in Northern Sweden during wintertime, can deteriorate the air quality even in small towns. To estimate the contribution of RWC to the total atmospheric aerosol loading, the positive matrix factorization (PMF) method was applied to hourly mean particle number size distributions measured in a residential area in Lycksele during winter 2005/2006. The sources were identified based on the particle number size distribution profiles of the PMF factors, the diurnal contributions patterns estimated by PMF for both weekends and weekdays, and correlation of the modeled particle number concentration per factor with measured aerosol mass concentrations (PM10, PM1, and light-absorbing carbon MLAC). Through these analyses, the factors were identified as local traffic (factor 1), local RWC (factor 2), and local RWC plus long-range transport (LRT) of aerosols (factor 3). In some occasions, it was difficult to detach the contributions of local RWC from background concentrations since their particle number size distributions partially overlapped and the model was not able to separate these two sources. As a consequence, we report the contribution of RWC as a range of values, being the minimum determined by factor 2 and the possible maximum as the contributions of both factors 2 and 3. A multiple linear regression (MLR) of observed PM10, PM1, total particle number, and MLAC concentrations is carried out to determine the source contribution to these aerosol variables. The results reveal RWC is an important source of atmospheric particles in the size range 25?606 nm (44?57%), PM10 (36?82%), PM1 (31?83%), and MLAC (40?76%) mass concentrations in the winter season. The contribution from RWC is especially large on weekends between 18:00 LT and midnight whereas local traffic emissions show similar contributions every day

Deterioration of air quality across Sweden due to transboundary agricultural burning emissions

Targino, A. C., Krecl, P., Johansson, C., Swietlicki, E., Massling, A., Coraiola, G. C. & Lihavainen, H. 2013: Deterioration of air quality across Sweden due to transboundary agricultural burning emissions. Boreal Env. Res. 18: 19-36. We analyzed measurements of aerosol and trace-gas concentrations from sites across Sweden before and during a series of agricultural wildland fires in eastern Europe in spring 2006. During the burning episodes, concentrations of background particulate matter (PM) and trace gases, such as carbon monoxide and ozone, increased, affecting air quality across the country and violating national air quality standards. The European Union PM10 daily limit value of 50 mu g m(-3) was exceeded during the pollution episodes even at the background stations, resulting in a nearly four-fold increase as compared with that in non-episode conditions. In relation to a non-episode period, the concentration rise in the accumulation-mode particles was from 40% at an urban site to 340% at a rural site, causing an increase in total particle number concentrations. The fires also boosted ground-level ozone, increasing concentrations of this pollutant by up to 100% at the background stations, which exceeded national air quality standards. Both elemental (EC) and organic carbon (OC) levels increased, with OC making a larger contribution to the total carbonaceous concentrations during the biomass burning episodes. The large-scale atmospheric circulation determined the strength and timing of the pollution events, with the eastern and northern sectors of Sweden experiencing two pollution pulses, whilst sites in the western and southern sectors were affected by one shorter episode. The results show that regional air quality deteriorated due to the long-range transport of pollutants emitted during agricultural wildfires

South East Pacific atmospheric composition and variability sampled along 20° S during VOCALS-REx

The VAMOS Ocean-Cloud-Atmosphere-Land Regional Experiment (VOCALS-REx) was conducted from 15 October to 15 November 2008 in the South East Pacific (SEP) region to investigate interactions between land, sea and atmosphere in this unique tropical eastern ocean environment and to improve the skill of global and regional models in representing the region. This study synthesises selected aircraft, ship and surface site observations from VOCALS-REx to statistically summarise and characterise the atmospheric composition and variability of the Marine Boundary Layer (MBL) and Free Troposphere (FT) along the 20° S parallel between 70° W and 85° W. Significant zonal gradients in mean MBL sub-micron aerosol particle size and composition, carbon monoxide, sulphur dioxide and ozone were seen over the campaign, with a generally more variable and polluted coastal environment and a less variable, more pristine remote maritime regime. Gradients in aerosol and trace gas concentrations were observed to be associated with strong gradients in cloud droplet number. The FT was often more polluted in terms of trace gases than the MBL in the mean; however increased variability in the FT composition suggests an episodic nature to elevated concentrations. This is consistent with a complex vertical interleaving of airmasses with diverse sources and hence pollutant concentrations as seen by generalised back trajectory analysis, which suggests contributions from both local and long-range sources. Furthermore, back trajectory analysis demonstrates that the observed zonal gradients both in the boundary layer and the free troposphere are characteristic of marked changes in airmass history with distance offshore – coastal boundary layer airmasses having been in recent contact with the local land surface and remote maritime airmasses having resided over ocean for in excess of ten days. Boundary layer composition to the east of 75° W was observed to be dominated by coastal emissions from sources to the west of the Andes, with evidence for diurnal pumping of the Andean boundary layer above the height of the marine capping inversion. Analysis of intra-campaign variability in atmospheric composition was not found to be significantly correlated with observed low-frequency variability in the large scale flow pattern; campaign-average interquartile ranges of CO, SO<sub>2</sub> and O<sub>3</sub> concentrations at all longitudes were observed to dominate over much smaller differences in median concentrations calculated between periods of different flow regimes. The campaign climatology presented here aims to provide a valuable dataset to inform model simulation and future process studies, particularly in the context of aerosol-cloud interaction and further evaluation of dynamical processes in the SEP region for conditions analogous to those during VOCALS-REx. To this end, our results are discussed in terms of coastal, transitional and remote spatial regimes in the MBL and FT and a gridded dataset are provided as a resource

Comparison of PM10 concentrations and metal content in three different sites of the Venice Lagoon: An analysis of possible aerosol sources

The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emissions on the mainland. In 2005, construction began on the mobile dams (MOSE), one dam for each channel connecting the lagoon to the Adriatic Sea as a barrier against high tide. These construction works could represent an additional source of pollutants. PM10 samples were taken on random days between 2007 and 2010 at three different sites: Punta Sabbioni, Chioggia and Malamocco, located near the respective dam construction worksites. Chemical analyses of V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl and Pb in PM10 samples were performed by Inductively coupled plasmaquadrupole mass spectrometry (ICP-QMS) and results were used to identify the main aerosol sources. The correlation of measured data with meteorology, and source apportionment, failed to highlight a contribution specifically associated to the emissions of the MOSE construction works. The comparison of the measurements at the three sites showed a substantial homogeneity of metal concentrations in the area. Source apportionment with principal component analysis (PCA) and positive matrix factorization (PMF) showed that a four principal factors model could describe the sources of metals in PM10. Three of them were assigned to specific sources in the area and one was characterised as a source of mixed origin (anthropogenic and crustal). A specific anthropogenic source of PM10 rich in Ni and Cr, active at the Chioggia site, was also identified

Historia på gymnasiet - En komparation av situationen vid Båstads gymnasium med utvalda frågor i NU03

I detta arbete undersöks med hjälp av en enkät hur mycket eleverna på Båstads Gymnasium kan om historiska sammanhang, om historiska fakta och hur elevernas inställning är gentemot utvalda värdegrunder. Undersökningen bygger på en enkät som jämförs med den Nationella Utvärderingen (NU03). Enkäten kommer fram till att eleverna i Båstad har grundläggande kunskaper inom historia och angående de värdegrunder som har undersöks lever eleverna över lag upp till dem. Typiskt för svaren från enkäten är dess oregelbundenhet. Det går endast i ett få antal fall att utläsa ett samband med yttre faktorer. Vid jämförelsen med NU03 kan man se att det finns stora likheter mellan dessa utvärderingar trots de delvis betydelsefulla skillnader som finns mellan utvärderingarna. Uppsatsen kommer också fram till att det för vissa frågor behövs fleråriga studier på gymnasiet att eleverna skall kunna förstå sammanhangen, att det inte räcker med bara en Historia A-kurs

Impact of residential wood combustion on urban air quality

Wood combustion is mainly used in cold regions as a primary or supplemental space heating source in residential areas. In several industrialized countries, there is a renewed interest in residential wood combustion (RWC) as an alternative to fossil fuel and nuclear power consumption. The main objective of this thesis was to investigate the impact of RWC on the air quality in urban areas. To this end, a field campaign was conducted in Northern Sweden during wintertime to characterize atmospheric aerosol particles and polycyclic aromatic hydrocarbons (PAH) and to determine their source apportionment. A large day-to-day and hour-to-hour variability in aerosol concentrations was observed during the intensive field campaign. On average, total carbon contributed a substantial fraction of PM10 mass concentrations (46%) and aerosol particles were mostly in the fine fraction (PM1 accounted for 76% of PM10). Evening aerosol concentrations were significantly higher on weekends than on weekdays which could be associated to the use of wood burning for recreational purposes or higher space heat demand when inhabitants spend longer time at home. It has been shown that continuous aerosol particle number size distribution measurements successfully provided source apportionment of atmospheric aerosol with high temporal resolution. The first compound-specific radiocarbon analysis (CSRA) of atmospheric PAH demonstrated its potential to provide quantitative information on the RWC contribution to individual PAH. RWC accounted for a large fraction of particle number concentrations in the size range 25-606 nm (44-57%), PM10 (36-82%), PM1 (31-83%), light-absorbing carbon (40-76%) and individual PAH (71-87%) mass concentrations. These studies have demonstrated that the impact of RWC on air quality in an urban location can be very important and largely exceed the contribution of vehicle emissions during winter, particularly under very stable atmospheric conditions

Impact of residential wood combustion on urban air quality

Wood combustion is mainly used in cold regions as a primary or supplemental space heating source in residential areas. In several industrialized countries, there is a renewed interest in residential wood combustion (RWC) as an alternative to fossil fuel and nuclear power consumption. The main objective of this thesis was to investigate the impact of RWC on the air quality in urban areas. To this end, a field campaign was conducted in Northern Sweden during wintertime to characterize atmospheric aerosol particles and polycyclic aromatic hydrocarbons (PAH) and to determine their source apportionment. A large day-to-day and hour-to-hour variability in aerosol concentrations was observed during the intensive field campaign. On average, total carbon contributed a substantial fraction of PM10 mass concentrations (46%) and aerosol particles were mostly in the fine fraction (PM1 accounted for 76% of PM10). Evening aerosol concentrations were significantly higher on weekends than on weekdays which could be associated to the use of wood burning for recreational purposes or higher space heat demand when inhabitants spend longer time at home. It has been shown that continuous aerosol particle number size distribution measurements successfully provided source apportionment of atmospheric aerosol with high temporal resolution. The first compound-specific radiocarbon analysis (CSRA) of atmospheric PAH demonstrated its potential to provide quantitative information on the RWC contribution to individual PAH. RWC accounted for a large fraction of particle number concentrations in the size range 25-606 nm (44-57%), PM10 (36-82%), PM1 (31-83%), light-absorbing carbon (40-76%) and individual PAH (71-87%) mass concentrations. These studies have demonstrated that the impact of RWC on air quality in an urban location can be very important and largely exceed the contribution of vehicle emissions during winter, particularly under very stable atmospheric conditions