Repozitorij Univerze v Novi Gorici

Iskanje po repozitoriju
A+ | A- | Pomoč | SLO | ENG

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 2 / 2
Na začetekNa prejšnjo stran1Na naslednjo stranNa konec
1.
Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory
J. Hueber, Sumit Kumar, J. A. Perlinger, Katja Džepina, Claudio Mazzoleni, Paulo Fialho, Swarup China, Bo Zhang, R. Chris Owen, D. Helmig, 2015, izvirni znanstveni članek

Opis: Free tropospheric aerosol was sampled at the Pico Mountain Observatory located at 2225 m above mean sea level on Pico Island of the Azores archipelago in the North Atlantic. The observatory is located ∼ 3900 km east and downwind of North America, which enables studies of free tropospheric air transported over long distances. Aerosol samples collected on filters from June to October 2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 µg m−3 . On average, organic aerosol components represent the largest mass fraction of the total measured aerosol (60 ± 51 %), followed by sulfate (23 ± 28 %), nitrate (13 ± 10 %), chloride (2 ± 3 %), and elemental carbon (2 ± 2 %). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and 9/25) collected consecutively during a pollution event were analyzed using ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned to each of the mass spectra in the range of m/z 100–1000. The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled air masses were very aged (average plume age > 12 days). These aged aerosol WSOM compounds had an average O /C ratio of ∼ 0.45, which is relatively low compared to O /C ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM and with the morphology and mixing state of particles as determined by scanning electron microscopy. The presence of markers characteristic of aqueous-phase reactions of phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses of 9/25 were more aged and influenced by marine emissions, as indicated by the presence of organosulfates and other species characteristic of marine aerosol. The change in the air masses for the two samples was corroborated by the changes in ethane, propane, and ozone, morphology of particles, as well as by the FLEXPART retroplume simulations. This paper presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere remote location and provides evidence of low oxygenation after long-range transport. We hypothesize this is a result of the selective removal of highly aged and polar species during long-range transport, because the aerosol underwent a combination of atmospheric processes during transport facilitating aqueous-phase removal (e.g., clouds processing) and fragmentation (e.g., photolysis) of components.
Najdeno v: osebi
Ključne besede: organic aerosol, ultrahigh-resolution FT-ICR MS, electron microscopy, remote marine atmosphere, Pico Mountain Observatory
Objavljeno: 11.04.2021; Ogledov: 284; Prenosov: 0
.pdf Polno besedilo (4,36 MB)

2.
Molekularna karakterizacija lebdećih čestica slobodne troposfere sa Opservatorija Pico planine
Sumit Kumar, J. A. Perlinger, D. Helmig, J. Hueber, Swarup China, B. Zhang, R. Chris Owen, Katja Džepina, Claudio Mazzoleni, Paulo Fialho, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Long-range transported free tropospheric aerosol was sampled at the PMO (38°28’15’’N, 28°24’14’’W; 2225 m amsl) on Pico Island of the Azores in the North Atlantic. Filter-collected aerosol during summer 2012 was analysed for organic and elemental carbon, and inorganic ions. The average aerosol ambient concentration was 0.9 µg m-3. Organic aerosol contributed the majority of mass (57%), followed by sulphate (21%) and nitrate (17%). Filter-collected aerosol was positively correlated with on-line aerosol measurements of black carbon, light scattering and number concentration. Water-soluble organic compounds (WSOC) from 9/24 and 9/25 samples collected during a pollution event were analysed with ultrahigh-resolution FT-ICR MS. FLEXPART analysis showed the air masses were very aged (>12 days). ~4000 molecular formulas were assigned to each of the mass spectra between m/z 100-1000. The majority of the assigned molecular formulas have unsaturated structures with CHO and CHNO elemental compositions. WSOC have an average O/C of ~0.45, relatively low compared to O/C of other aged aerosol, which might be the result of evaporation and fragmentation during long-range transport. The increase in aerosol loading during 9/24 was linked to biomass burning emissions from North America by FLEXPART and MODIS fire counts. This was confirmed with WSOC biomass burning markers and with the morphology and mixing state of particles as determined by SEM. The presence of markers characteristic of aqueous-phase reactions of biomass burning phenolic species suggests that the aerosol collected at Pico had undergone cloud processing. The air masses on 9/25 were more aged (~15 days) and influenced by marine emissions, as indicated by organosulphates and species characteristic for marine aerosol (e.g. fatty acids). The change in air masses for the two samples was corroborated by the changes in ozone, ethane, propane, morphology of particles, as well as by FLEXPART. In this presentation we will presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at the PMO.
Najdeno v: osebi
Ključne besede: Atmospheric aerosol, Free troposphere, Mass spectrometry, Pico mountain observatory
Objavljeno: 26.05.2021; Ogledov: 272; Prenosov: 0
.pdf Polno besedilo (8,36 MB)

Iskanje izvedeno v 0 sek.
Na vrh