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Sökning: L773:1352 2310

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31.
  • Ahlberg, Erik, et al. (författare)
  • Secondary organic aerosol from VOC mixtures in an oxidation flow reactor
  • 2017
  • Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 161, s. 210-220
  • Tidskriftsartikel (refereegranskat)abstract
    • The atmospheric organic aerosol is a tremendously complex system in terms of chemical content. Models generally treat the mixtures as ideal, something which has been questioned owing to model-measurement discrepancies. We used an oxidation flow reactor to produce secondary organic aerosol (SOA) mixtures containing oxidation products of biogenic (α-pinene, myrcene and isoprene) and anthropogenic (m-xylene) volatile organic compounds (VOCs). The resulting volume concentration and chemical composition was measured using a scanning mobility particle sizer (SMPS) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), respectively. The SOA mass yield of the mixtures was compared to a partitioning model constructed from single VOC experiments. The single VOC SOA mass yields with no wall-loss correction applied are comparable to previous experiments. In the mixtures containing myrcene a higher yield than expected was produced. We attribute this to an increased condensation sink, arising from myrcene producing a significantly higher number of nucleation particles compared to the other precursors. Isoprene did not produce much mass in single VOC experiments but contributed to the mass of the mixtures. The effect of high concentrations of isoprene on the OH exposure was found to be small, even at OH reactivities that previously have been reported to significantly suppress OH exposures in oxidation flow reactors. Furthermore, isoprene shifted the particle size distribution of mixtures towards larger sizes, which could be due to a change in oxidant dynamics inside the reactor.
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32.
  • Ahmed, Trifa M., et al. (författare)
  • Native and oxygenated polycyclic aromatic hydrocarbons in ambient air particulate matter from the city of Sulaimaniyah in Iraq
  • 2015
  • Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 116, s. 44-50
  • Tidskriftsartikel (refereegranskat)abstract
    • The concentrations of 43 polycyclic aromatic hydrocarbons (PAHs) and 4 oxygenated PAHs (OPAHs) are reported for the first time in particulate matter (PM10) sampled in the air of the city of Sulaimaniyah in Iraq. The total PAH concentration at the different sampling sites varied between 9.3 and 114 ng/m(3). The corresponding values of the human carcinogen benzotalpyrene were between 0.3 and 6.9 ng/m(3), with most samples exceeding the EU annual target value of 1 ng/m(3). The highly carcinogenic dibenzopyrene isomers dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene and dibenzo[a,h]pyrene constituted 0.1-0.4% of the total PAH concentration. However, when scaling for relative cancer potencies using toxic equivalency factors, a benzo[a]pyrene equivalent concentration of dibenzo[a,l]pyrene equal to that of benzo[a]pyrene was obtained, indicating that the contribution of dibenzo[a,l]pyrene to the carcinogenicity of the PAHs could be similar to that of benzo[a]pyrene. A high correlation between the determined concentrations of the dibenzopyrene isomers and benzo[a]pyrene was found, which supported the use of benzo[a]pyrene as an indicator for the carcinogenicity of PAHs in ambient air. The total concentrations of the four OPAHs, 9,10-anthraquinone, 4H-cyclopenta[def]phenanthren-4-one, benzanthrone, and 7,12-benz[a]anthraquinone, varied between 0.6 and 8.1 ng/m(3), with 9,10-anthraquinone being the most abundant OPAH in all of the samples.
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33.
  • Ahn, Seo H., et al. (författare)
  • Relationship between cloud condensation nuclei (CCN) concentration and aerosol optical depth in the Arctic region
  • 2021
  • Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 267
  • Tidskriftsartikel (refereegranskat)abstract
    • To determine the direct and indirect effects of aerosols on climate, it is important to know the spatial and temporal variations in cloud condensation nuclei (CCN) concentrations. Although many types of CCN measurements are available, extensive CCN measurements are challenging because of the complexity and high operating cost, especially in remote areas. As aerosol optical depth (AOD) can be readily observed by remote sensing, many attempts have been made to estimate CCN concentrations from AOD. In this study, the CCN-AOD relationship is parameterized based on CCN ground measurements from the Zeppelin Observatory (78.91 degrees N, 11.89 degrees E, 474 m asl) in the Arctic region. The AOD measurements were obtained from the Ny-Alesund site (78.923 degrees N, 11.928 degrees E) and Modern-Era Retrospective Analysis for Research and Applications, Version 2 reanalysis. Our results show a CCN-AOD correlation with a coefficient of determination R-2 of 0.59. Three additional estimation models for CCN were presented based on the following data: (i) in situ aerosol chemical composition, (ii) in situ aerosol optical properties, and (iii) chemical composition of AOD obtained from reanalysis data. The results from the model using in situ aerosol optical properties reproduced the observed CCN concentration most efficiently, suggesting that the contribution of BC to CCN concentration should be considered along with that of sulfate.
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34.
  • Ahrens, Lutz (författare)
  • Concentrations in air of organobromine, organochlorine and organophosphate flame retardants in Toronto, Canada
  • 2014
  • Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 99, s. 140-147
  • Tidskriftsartikel (refereegranskat)abstract
    • Concentrations of organobromine (BFRs), organochlorine (CFRs) and organophosphate esters flame retardants and plasticizers (PFRs) in air were monitored for over one year at an urban site in Toronto, Canada during 2010-2011. The mean value for polybrominated diphenyl ethers (BDEs) (gas + particle phase) was 38 pg/m(3) with BDE-47 and BDE-99 as the dominant congeners. The mean concentrations in air for Sigma non-BDE (BFRs and CFRs), was 9.6 pg/m(3) about four times lower than the BDEs. The brominated FRs: TBP-AE, BTBPE, EH-TBB, BEH-TEBP and the chlorinated syn- and anti-DP were detected frequently, ranging from 87% to 96%. Highest concentrations in air among all flame retardant classes were observed for the Sigma-PFRs. The yearly mean concentration in air for EPFRs was 2643 pg/m(3) with detection frequency higher than 80%. Except for TBP-AE and b- DBE-DBCH, non-BDEs (BFRs, CFRs and PFRs) were mainly associated with the particle phase. BDE concentrations in air were positively correlated with temperature indicating that volatilization from local sources was an important factor controlling levels in air. This correlation did not hold for most BFRs, CFRs and PFRs which were mainly on particles. For these compounds, air concentrations in Toronto are likely related to emissions from point sources and advective inputs. This study highlights the importance of urban air monitoring for FRs. Urban air can be considered a sentinel for detecting changes in the use and application of FRs in commercial products. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved.
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35.
  • Alves, C. A., et al. (författare)
  • Physical and chemical properties of non-exhaust particles generated from wear between pavements and tyres
  • 2020
  • Ingår i: Atmospheric Environment. - : Elsevier Ltd. - 1352-2310 .- 1873-2844. ; 224
  • Tidskriftsartikel (refereegranskat)abstract
    • A road simulator was used to generate wear particles from the interaction between two tyre brands and a composite pavement. Particle size distributions were monitored using a scanning mobility particle sizer and an aerosol particle sizer. Continuous measurements of particle mass concentrations were also made. Collection of inhalable particles (PM10) was conducted using a high-volume sampler equipped with quartz filters, which were then analysed for organic and elemental carbon, organic constituents and elemental composition. Tyre fragments chopped into tiny chips were also subjected to detailed organic and elemental speciation. The number concentration was dominated by particles <0.5 μm, whereas most of the mass was found in particles >0.5 μm. The emission factor from wear between pavements and tyres was of the order of 2 mg km−1 veh−1. Organic carbon represented about 10% of the PM10 mass, encompassing multiple aliphatic compounds (n-alkanes, alkenes, hopanes, and steranes), PAHs, thiazols, n-alkanols, polyols, some fragrant compounds, sugars, triterpenoids, sterols, phenolic constituents, phthalate plasticisers and several types of acids, among others. The relationship between airborne particulate organic constituents and organic matter in tyre debris is discussed. The detection of compounds that have been extensively used as biomass burning tracers (e.g. retene, dehydroabietic acid and levoglucosan) in both the shredded tiny tyre chips and the wear particles from the interaction between tyres and pavement puts into question their uniqueness as markers of wood combustion. Trace and major elements accounted for about 5% of the mass of the tyre fragments but represented 15–18% of the PM10 from wear, denoting the contribution of mineral elements from the pavement. Sulphur and zinc were abundant constituents in all samples.
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36.
  • Alves, Celia, et al. (författare)
  • Organic compounds in aerosols from selected European sites - Biogenic versus anthropogenic sources
  • 2012
  • Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 59, s. 243-255
  • Tidskriftsartikel (refereegranskat)abstract
    • Atmospheric aerosol samples from a boreal forest (Hyytiala, April 2007), a rural site in Hungary (K-puszta, summer 2008), a polluted rural area in Italy (San Pietro Capofiume, Po Valley, April 2008), a moderately polluted rural site in Germany located on a meadow (Melpitz, May 2008), a natural park in Spain (Montseny, March 2009) and two urban background locations (Zurich, December 2008, and Barcelona, February/March 2009) were collected. Aliphatics, polycyclic aromatic hydrocarbons, carbonyls, sterols, n-alkanols, acids, phenolic compounds and anhydrosugars in aerosols were chemically characterised by gas chromatography-mass spectrometry, along with source attribution based on the carbon preference index (CPI), the rations between the unresolved and the chromatographically resolved aliphatics, the contribution of wax n-alkanes, n-alkanols and n-alkanoic acids from plants, diagnostic ratios of individual target compounds and source-specific markers to organic carbon ratios. In spite of transboundary pollution episodes, Hyytiala registered the lowest levels among all locations. CPI values close to 1 for the aliphatic fraction of the Montseny aerosol suggest that the anthropogenic input may be associated with the transport of aged air masses from the surrounding industrial/urban areas, which superimpose the locally originated hydrocarbons with biogenic origin. Aliphatic and aromatic hydrocarbons in samples from San Pietro Capofiume reveal that fossil fuel combustion is a major source influencing the diel pattern of concentrations. This source contributed to 25-45% of the ambient organic carbon (OC) at the Po Valley site. Aerosols from the German meadow presented variable contributions from both biogenic and anthropogenic sources. The highest levels of vegetation wax components and biogenic secondary organic aerosol (SOA) products were observed at K-puszta, while anthropogenic SOA compounds predominated in Barcelona. The primary vehicular emissions in the Spanish city accounted for around 25-30% of the OC in aerosols. Besides the traffic input (10% of OC), residential wood burning was found to be another dominant emission source contributing to the atmospheric aerosol (up to 38% of OC) at the Swiss urban location. It was estimated that around 10% of the OC mass in the urban sites originates from cooking emissions. Aerosols from the urban area of Zurich presented a much higher PAH content, and benzo(a)pyrene equivalent concentrations sometimes exceeding the mandatory limit. (C) 2012 Elsevier Ltd. All rights reserved.
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37.
  • Anderson, Maria, 1983, et al. (författare)
  • Characterization of particles from a marine engine operating at low loads
  • 2015
  • Ingår i: Atmospheric Environment. - : Elsevier BV. - 1873-2844 .- 1352-2310. ; 101, s. 65-71
  • Tidskriftsartikel (refereegranskat)abstract
    • Particle emissions from a marine diesel engine operating at low loads with four different fuels were characterized with respect to particle number (PN) and particle mass (PM), size distribution, volatility and chemical composition. The four different fuels used were Swedish Environmental class 1 (MK1) and class 3 diesel (MK3), heavy fuel oil (HFO, 0.12 wt% S) and marine diesel oil (MDO, 0.52 wt% S). The measurements were performed for a marine diesel engine in a test-bed engine lab and the particle emissions were measured with an Engine Exhaust Particle Sizer and a Dust Monitor, giving the number concentrations in the size range of 5.6-560 nm and 300 nm to 20 gm, respectively. To quantify the amount of solid particles a thermodenuder was used. Additionally, filter samples were taken for gravimetric, black carbon (BC) and elemental analysis. The particle emissions showed a bimodal size distribution by number and the number concentrations were dominated by nanoparticles (diameter (Dp) 50 nm generally were solid primary particles. Combustion of HFO resulted in the highest PN and PM concentrations. Emission factors (EFs) for PM and PN for both the total particle emissions and the fraction of primary, solid particles are presented for different fuels and loads. EFs for nitrogen oxides (NOx), BC and some elements (Ca, Fe, V, Ni, Zn) are presented as well. This study contributes to understanding particle emissions from potential future fuels as well as emissions in ports and coastal areas where lower engine loads are common.
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38.
  • Andersson, August, et al. (författare)
  • (14)C-Based source assessment of soot aerosols in Stockholm and the Swedish EMEP-Aspvreten regional background site
  • 2011
  • Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 45:1, s. 215-222
  • Tidskriftsartikel (refereegranskat)abstract
    • Combustion-derived soot or black carbon (BC) in the atmosphere has a strong influence on both climate and human health. In order to propose effective mitigation strategies for BC emissions it is of importance to investigate geographical distributions and seasonal variations of BC emission sources. Here, a radiocarbon methodology is used to distinguish between fossil fuel and biomass burning sources of soot carbon (SC). SC is isolated for subsequent off-line (14)C quantification with the chemothermal oxidation method at 375 degrees C (CTO-375 method), which reflects a recalcitrant portion of the BC continuum known to minimize inadvertent inclusion of any non-pyrogenic organic matter. Monitored wind directions largely excluded impact from the Stockholm metropolitan region at the EMEP-Aspvreten rural station 70 km to the south-west. Nevertheless, the Stockholm city and the rural stations yielded similar relative source contributions with fraction biomass (f(biomass)) for fall and winter periods in the range of one-third to half. Large temporal variations in (14)C-based source apportionment was noted for both the 6 week fall and the 4 month winter observations. The f(biomass) appeared to be related to the SC concentration suggesting that periods of elevated BC levels may be caused by increased wood fuel combustion. These results for the largest metropolitan area in Scandinavia combine with other recent (14)C-based studies of combustion-derived aerosol fractions to suggest that biofuel combustion is contributing a large portion of the BC load to the northern European atmosphere.
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39.
  • Andersson, Camilla, 1979-, et al. (författare)
  • Population exposure and mortality due to regional background PM in Europe – longterm simulations of source-region and shipping contributions
  • 2009
  • Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 43:22-23, s. 3614-3620
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the contribution to population exposure (PE) of regional background fine primary (PPM2.5) and secondary inorganic (SIA) particulate matter and its impact on mortality in Europe during 1997–2003 calculated with a chemistry transport model. Contributions to concentrations and PE due to emissions from shipping, Western (WEU), Eastern (EEU), and Northern Europe are compared. WEU contributes about 40% to both PPM2.5 and SIA concentrations, whereas the EEU contribution to PPM2.5 is much higher (43% of total PPM2.5) than to SIA (29% of total SIA). The population weighted average concentration (PWC) of PPM2.5 is a factor of 2.3 higher than average (non-weighted) concentrations, whereas for SIA the PWC is only a factor 1.6 higher. This is due to PPM2.5 concentrations having larger gradients and being relatively high over densely populated areas, whereas SIA is formed outside populated areas. WEU emissions contribute relatively more than EEU to PWC and mortality due to both PPM2.5 and SIA in Europe. The number of premature deaths in Europe is estimated to 301 000 per year due to PPM2.5 exposure and 245 000 due to SIA, despite 3.3 times higher average SIA concentrations. This is due to population weighting and assumed (and uncertain) higher relative risk of mortality for PPM2.5 components (2.8 times higher RR for PPM2.5). This study indicates that it might be more efficient, for the health of the European population, to decrease primary PM emissions (especially in WEU) than to decrease precursors of SIA, but more knowledge on the toxicity of different PM constituents is needed before firm conclusions can be drawn.
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40.
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