| 1. |
- Ahlberg, Erik, et al.
(författare)
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Measurement report : Black carbon properties and concentrations in southern Sweden urban and rural air-the importance of long-range transport
- 2023
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 23:5, s. 3051-3064
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Tidskriftsartikel (refereegranskat)abstract
- Soot, or black carbon (BC), aerosol is a major climate forcer with severe health effects. The impacts depend strongly on particle number concentration, size and mixing state. This work reports on two field campaigns at nearby urban and rural sites, 65gkm apart, in southern Sweden during late summer 2018. BC was measured using a single-particle soot photometer (SP2) and Aethalometers (AE33). Differences in BC concentrations between the sites are driven primarily by local traffic emissions. Equivalent and refractory BC mass concentrations at the urban site were on average a factor 2.2 and 2.5, with peaks during rush hour up to a factor g1/44, higher than the rural background levels. The number fraction of particles containing a soot core was significantly higher in the city. BC particles at the urban site were on average smaller by mass and had less coating owing to fresh traffic emissions. The organic components of the fresh traffic plumes were similar in mass spectral signature to hydrocarbon-like organic aerosol (HOA), commonly associated with traffic. Despite the intense local traffic (g1/4g30g000 vehicles passing per day), PM1, including organic aerosol, was dominated by aged continental air masses even at the curbside site. The fraction of thickly coated particles at the urban site was highly correlated with the mass concentrations of all measured chemical species of PM1, consistent with aged, internally mixed aerosol. Trajectory analysis for the whole year showed that air masses arriving at the rural site from eastern Europe contained approximately double the amount of BC compared to air masses from western Europe. Furthermore, the largest regional emissions of BC transported to the rural site, from the Malmö-Copenhagen urban area, are discernible above background levels only when precipitation events are excluded. We show that continental Europe and not the Malmö-Copenhagen region is the major contributor to the background BC mass concentrations in southern Sweden.
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| 2. |
- Ahlberg, Erik, et al.
(författare)
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No particle mass enhancement from induced atmospheric ageing at a rural site in northern Europe
- 2019
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- A large portion of atmospheric aerosol particles consists of secondary material produced by oxidation reactions. The relative importance of secondary organic aerosol (SOA) can increase with improved emission regulations. A relatively simple way to study potential particle formation in the atmosphere is by using oxidation flow reactors (OFRs) which simulate atmospheric ageing. Here we report on the first ambient OFR ageing experiment in Europe, coupled with scanning mobility particle sizer (SMPS), aerosol mass spectrometer (AMS) and proton transfer reaction (PTR)-MS measurements. We found that the simulated ageing did not produce any measurable increases in particle mass or number concentrations during the two months of the campaign due to low concentrations of precursors. Losses in the reactor increased with hydroxyl radical (OH) exposure and with increasing difference between ambient and reactor temperatures, indicating fragmentation and evaporation of semivolatile material.
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| 3. |
- Andersen, Christina, et al.
(författare)
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Atmospheric Chemistry of Tetrahydrofuran, 2-Methyltetrahydrofuran, and 2,5-Dimethyltetrahydrofuran : Kinetics of Reactions with Chlorine Atoms, OD Radicals, and Ozone
- 2016
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Ingår i: The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory. - : American Chemical Society (ACS). - 1089-5639. ; 120:37, s. 7320-7326
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Tidskriftsartikel (refereegranskat)abstract
- FTIR smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl atoms, OD radicals, and O3 with the five-membered ring-structured compounds tetrahydrofuran (C4H8O, THF), 2-methyltetrahydrofuran (CH3C4H7O, 2-MTHF), 2,5-dimethyltetrahydrofuran ((CH3)2C4H5O, 2,5-DMTHF), and furan (C4H4O). The rate coefficients determined using relative rate methods were kTHF+Cl = (1.96 ± 0.24) × 10-10, kTHF+OD = (1.81 ± 0.27) × 10-11, kTHF+O3 = (6.41 ± 2.90) × 10-21, k2-MTHF+Cl = (2.65 ± 0.43) × 10-10, k2-MTHF+OD = (2.41 ± 0.51) × 10-11, k2-MTHF+O3 = (1.87 ± 0.82) × 10-20, k2,5-DMTHF+OD = (4.56 ± 0.68) × 10-11, k2,5-DMTHF+Cl = (2.84 ± 0.34) × 10-10, k2,5-DMTHF+O3 = (4.58 ± 2.18), kfuran+Cl = (2.39 ± 0.27) × 10-10, and kfuran+O3 = (2.60 ± 0.31) × 10-18 molecules cm-3 s-1. Rate coefficients of the reactions with ozone were also determined using the absolute rate method under pseudo-first-order conditions. OD radicals, in place of OH radicals, were produced from CD3ONO to avoid spectral overlap of isopropyl and methyl nitrite with the reactants. The kinetics of OD radical reactions are expected to resemble the kinetics of OH radical reactions, and the rate coefficients of the reactions with OD radicals were used to calculate the atmospheric lifetimes with respect to reactions with OH radicals. The lifetimes of THF, 2-MTHF, and 2,5-DMTHF are approximately 15, 12, and 6 h, respectively.
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| 4. |
- Ausmeel, Stina
(författare)
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Born in fire, borne by air : Source attribution and physicochemical characterization of ship and ambient aerosols in the Baltic region
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aerosol emissions from anthropogenic activities cause detrimental health effects and affect the climate system. Combustion is a large source of airborne fine particulate matter (PM2.5) and the uncertainties of the climate role of these emissions are still large. A good understanding of the microphysical properties of aerosols from various sources and their atmospheric aging is essential for accurate assessment of the health and climate impact. It is also important to follow up legislative actions aimed at reducing emissions, with ambient observations. The overall aim of this thesis is to present results from field observations of aerosols from combustion sources, and contribute to the general knowledge on the particle concentrations and physicochemical properties in the Baltic region. Ship and traffic emissions were investigated in detail in several field campaigns in Sweden. Soot, or black carbon, was specifically measured with several different measurement techniques. Other aerosol components were also monitored, including gaseous species, organic matter, and sulfate, which is of specific interest in ship emission characterization. Additionally, source apportionment of the carbonaceous aerosol from a field campaign in northern Poland is presented, which adds to the knowledge about black carbon emissions in a polluted part of Europe. The absorbing equivalent black carbon emission factor (EFeBC) was measured for over 300 fresh ship plumes in a Port within a sulfur emission control area. EFeBC had decreased by 30 %, from 0.48±0.81 to 0.34±0.40 g(kg fuel)-1 between 2014 and 2015 after a reduction of fuel sulfur content. If such a reduction is expected as marine fuel quality is improved, this can have important implications also outside emission control areas, as a global sulfur cap is implemented. A more complete physicochemical characterization and simulated aging of ship plumes of an age between about 20 and 30 minutes was performed at a coastline, and the contribution of one shipping lane to local aerosol concentration was quantified. Novel methods to tie plumes to individual ships and to estimate contribution to coastal exposure were developed. Ships contributed as much as 10-18 % of ultrafine particles at the coast, but only about 1 % or less (40 ng m-3) to local PM. Non-refractory PM1 was mainly organics and sulfate (56 and 36 %, respectively), and the average eBC contribution was 3.5±1.7 ng m-3. The absorption Ångström exponent of the plume eBC was close to unity, indicating black (BC) rather than brown carbon (BrC). Oxidation flow reactor treatment of the aerosol was performed, resulting in occasionally strong increase in secondary aerosol mass.The ambient aerosol and its BC fraction was characterized in an urban and rural environment in southern Sweden, and the transport of the aerosol between these nearby sites was investigated. The conclusion was that there was 2.2-2.5 times higher BC mass and up to four times higher BC number concentration at the urban site. Additionally, the soot particles in the city were slightly smaller and less coated. The influence of an urban plume at the rural site was possible to detect and quantify during specific meteorological conditions. The regional background dominated the total aerosol contribution, and was largely due to southeastern air masses.A quantification of particle sources in Polish air is lacking. Winter field campaign data from northeastern Poland showed that domestic coal combustion, domestic wood combustion and traffic contributed 41, 21, and 38 % respectively to carbonaceous particulate matter. The three sources were separated using a combination of apportionment methods based on aerosol absorption properties and chemical markers.Generally, the eBC concentrations were approximately twice as high in Poland as in Sweden, and twice as high in a Swedish city compared to a rural background site. Emissions from a large shipping lane were not a large source of eBC at the coastal sampling site. However, despite the relatively good air quality in Sweden, air pollution is still above the environmental quality objectives, and of importance to health locally, and climate in general.
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| 5. |
- Ausmeel, Stina, et al.
(författare)
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Methods for identifying aged ship plumes and estimating contribution to aerosol exposure downwind of shipping lanes
- 2019
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 12:8, s. 4479-4493
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Tidskriftsartikel (refereegranskat)abstract
- Ship traffic is a major source of aerosol particles, particularly near shipping lanes and harbours. In order to estimate the contribution to exposure downwind of a shipping lane, it is important to be able to measure the ship emission contribution at various distances from the source. We report on measurements of atmospheric particles 7-20 km downwind of a shipping lane in the Baltic Sea Sulfur Emission Control Area (SECA) at a coastal location in southern Sweden during a winter and a summer campaign. Each ship plume was linked to individual ship passages using a novel method based on wind field data and automatic ship identification system data (AIS), where varying wind speeds and directions were applied to calculate a plume trajectory. In a situation where AIS data are not matching measured plumes well or if AIS data are missing, we provide an alternative method with particle number concentration data. The shipping lane contribution to the particle number concentration in Falsterbo was estimated by subtracting background concentrations from the ship plume concentrations, and more than 150 plumes were analysed. We have also extrapolated the contribution to seasonal averages and provide recommendations for future similar measurements. Averaged over a season, the contribution to particle number concentration was about 18 % during the winter and 10 % during the summer, including those periods with wind directions when the shipping lane was not affecting the station. The corresponding contribution to equivalent black carbon was 1.4 %..
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| 6. |
- Ausmeel, Stina, et al.
(författare)
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Ship plumes in the Baltic Sea Sulfur Emission Control Area: chemical characterization and contribution to coastal aerosol concentrations
- 2020
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 20:15, s. 9135-9151
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Tidskriftsartikel (refereegranskat)abstract
- In coastal areas, there is increased concern aboutemissions from shipping activities and the associated impacton air quality. We have assessed the ship aerosol propertiesand the contribution to coastal particulate matter (PM) andnitrogen dioxide (NO2) levels by measuring ship plumes inambient conditions at a site in southern Sweden, within a SulfurEmission Control Area. Measurements took place duringa summer and a winter campaign, 10 km downwind ofa major shipping lane. Individual ships showed large variabilityin contribution to total particle mass, organics, sulfate,and NO2. The average emission contribution of theshipping lane was 2913 and 3720 ngm?3 to PM0:5,188 and 3419 ngm?3 to PM0:15, and 1:210:57 and1:110:61 μgm?3 to NO2, during winter and summer, respectively.Sulfate and organics dominated the particle massand most plumes contained undetectable amounts of equivalentblack carbon (eBC). The average eBC contribution was3:51:7 ngm?3 and the absorption Ångström exponent wasclose to 1. Simulated ageing of the ship aerosols using anoxidation flow reactor showed that on a few occasions, therewas an increase in sulfate and organic mass after photochemicalprocessing of the plumes. However, most plumes did notproduce measurable amounts of secondary PM upon simulatedageing.
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| 7. |
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| 8. |
- Kristensson, Adam, et al.
(författare)
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Source contributions to rural carbonaceous winter aerosol in North-Eastern Poland
- 2020
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Concentrations of aerosol particles in Poland and their sources are rarely discussed in peer-reviewed journal articles despite serious air quality issues. A source apportionment of carbonaceous aerosol particles was performed during winter at a rural background environment field site in north-eastern Poland. Data were used of light absorption at seven wavelengths and levoglucosan concentrations along existing monitoring of PM2.5, organic carbon and elemental carbon (OC/EC) at the Diabla Gora EMEP monitoring site between January 17 and March 19 during the EMEP intensive winter campaign of 2018. Average PM2.5, OC, EC, equivalent black carbon (eBC) and levoglucosan concentrations and standard deviations amounted to 18.5 ± 9.3, 4.5 ± 2.5, 0.57 ± 0.28, 1.04 ± 0.62 and 0.134 ± 0.084 μg m-3 respectively. Various tools for source apportionment were used to obtain a source contribution to carbonaceous matter (CM) with three components. The wood combustion source component contributed 1.63 μg m-3 (21%), domestic coal combustion 3.3 μg m-3 (41%) and road transport exhaust 2.9 μg m-3 (38%). Similar levels and temporal variability were found for the nearby Lithuanian site of Preila, corroborating the Polish results.
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| 9. |
- Laj, Paolo, et al.
(författare)
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A global analysis of climate-relevant aerosol properties retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
- 2020
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 13:8, s. 4353-4392
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol particles are essential constituents of the Earth's atmosphere, impacting the earth radiation balance directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. In contrast to most greenhouse gases, aerosol particles have short atmospheric residence times, resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at regional scale through observations involving, in particular, the in situ near-surface segment of the atmospheric observation system. This paper will provide the widest effort so far to document variability of climate-relevant in situ aerosol properties (namely wavelength dependent particle light scattering and absorption coefficients, particle number concentration and particle number size distribution) from all sites connected to the Global Atmosphere Watch network. High-quality data from almost 90 stations worldwide have been collected and controlled for quality and are reported for a reference year in 2017, providing a very extended and robust view of the variability of these variables worldwide. The range of variability observed worldwide for light scattering and absorption coefficients, single-scattering albedo, and particle number concentration are presented together with preliminary information on their long-term trends and comparison with model simulation for the different stations. The scope of the present paper is also to provide the necessary suite of information, including data provision procedures, quality control and analysis, data policy, and usage of the ground-based aerosol measurement network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in the form of a fully characterized value chain, including uncertainty estimation and requirements for contributing to the global climate monitoring system.
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