| 1. |
- Espen Yttri, Karl, et al.
(författare)
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Trends, composition, and sources of carbonaceous aerosol at the Birkenes Observatory, northern Europe, 2001-2018
- 2021
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:9, s. 7149-7170
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Tidskriftsartikel (refereegranskat)abstract
- We present 18 years (2001-2018) of aerosol measurements, including organic and elemental carbon (OC and EC), organic tracers (levoglucosan, arabitol, mannitol, trehalose, glucose, and 2-methyltetrols), trace elements, and ions, at the Birkenes Observatory (southern Norway) - a site representative of the northern European region. The OC=EC (2001-2018) and the levoglucosan (2008-2018) time series are the longest in Europe, with OC=EC available for the PM10, PM2:5 (fine), and PM10-2:5 (coarse) size fractions, providing the opportunity for a nearly 2-decade-long assessment. Using positive matrix factorization (PMF), we identify seven carbonaceous aerosol sources at Birkenes: mineraldust- dominated aerosol (MIN), traffic/industry-like aerosol (TRA/IND), short-range-transported biogenic secondary organic aerosol (BSOASRT), primary biological aerosol particles (PBAP), biomass burning aerosol (BB), ammoniumnitrate- dominated aerosol (NH4NO3), and (one low carbon fraction) sea salt aerosol (SS). We observed significant (p < 0:05), large decreases in EC in PM10 (-3:9%yr-1) and PM2:5 (-4:2%yr-1) and a smaller decline in levoglucosan (-2:8%yr-1), suggesting that OC=EC from traffic and industry is decreasing, whereas the abatement of OC=EC from biomass burning has been slightly less successful. EC abatement with respect to anthropogenic sources is further supported by decreasing EC fractions in PM2:5 (-3:9%yr-1) and PM10 (-4:5%yr-1). PMF apportioned 72% of EC to fossil fuel sources; this was further supported by PMF applied to absorption photometer data, which yielded a two-factor solution with a low aerosol ngstr m exponent (AAED0.93) fraction, assumed to be equivalent black carbon from fossil fuel combustion (eBCFF), contributing 78% to eBC mass. The higher AAE fraction (AAED2.04) is likely eBC from BB (eBCBB). Source-receptor model calculations (FLEXPART) showed that continental Europe and western Russia were the main source regions of both elevated eBCBB and eBCFF. Dominating biogenic sources explain why there was no downward trend for OC. A relative increase in the OC fraction in PM2:5 (C3:2%yr-1) and PM10 (C2:4%yr-1) underscores the importance of biogenic sources at Birkenes (BSOA and PBAP), which were higher in the vegetative season and dominated both fine (53 %) and coarse (78 %) OC. Furthermore, 77 %-91% of OC in PM2:5, PM10-2:5, and PM10 was attributed to biogenic sources in summer vs. 22 %- 37% in winter. The coarse fraction had the highest share of biogenic sources regardless of season and was dominated by PBAP, except in winter. Our results show a shift in the aerosol composition at Birkenes and, thus, also in the relative source contributions. The need for diverse offline and online carbonaceous aerosol speciation to understand carbonaceous aerosol sources, including their seasonal, annual, and long-term variability, has been demonstrated.
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| 2. |
- Nøjgaard, J. K., et al.
(författare)
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A local marine source of atmospheric particles in the High Arctic
- 2022
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 285
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Tidskriftsartikel (refereegranskat)abstract
- The chemical composition of non-refractory submicron aerosol (NR-PM1) was characterized at the Villum Research Station (Villum) at Station Nord in North Greenland during spring-summer 2016 using a Time of Flight Aerosol Chemical Speciation Monitor (ToF-ACSM). The composition is dominated by sulfate (48%) and organic species (40%). Positive Matrix Factorization (PMF) identified three key factors corresponding to a primary hydrocarbon-like organic aerosol (HOA), and two types of secondary organic aerosol: oxygenated organic aerosol (OOA) and a marine organic aerosol (MOA). The HOA factor accounts for 5% of the organic aerosol mass, which is consistent with previous findings at Villum. The OOA factor accounts for 77% of the organic aerosol mass and correlates with accumulation mode particles, which supports previous findings indicating that oxidized organic aerosols are predominantly from long-range transport during winter and spring at Villum. The MOA factor was characterized by mass spectral fragments of methane sulfonic acid (MSA) from atmospheric oxidation of dimethyl sulfide, for which reason the MOA factor is considered to be of biogenic origin. MOA accounts for 18% of the organic aerosol mass and correlates with locally produced Aitken mode particles. This indicates that biogenic processes are not only a significant source of aerosols at Villum, but MOA also appears to be formed in the vicinity of the measurement site. This local geographical origin was confirmed through air mass back trajectory modelling and source-receptor analysis. During May, air masses frequently arrived from the east, with source regions for the MOA factor and therewith MSA located in the Barents Sea and Lincoln Sea with lesser contributions from the Greenland Sea. During June, air mass origin shifted to the west, with source regions for the MOA factor and MSA shifting correspondingly to Baffin Bay and the Canadian Arctic Archipelago. While shifting transport patterns between May and June lead to shifting source regions, sea ice likely played a role as well. During May, marginal ice zones were present in the Barents Sea between Svalbard and Franz Josef Land, while during June, sea ice in the northern part of Baffin Bay retreated and sea ice in the Canadian Arctic Archipelago decreased. Although May and June experienced different transport patterns and sea ice conditions, levels of the MOA factor and MSA were similar between the months. This is likely due to similarities between marine biological activities in the Barents Sea and Baffin Bay. This research highlights the complex relationship between transport patterns, sea ice conditions, and atmospheric particle concentrations. Multiyear aerosol chemical composition from several High Arctic sites is encouraged to determine the full effects of ocean-atmosphere interactions and transport patterns on atmospheric aerosol concentrations.
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| 3. |
- Pospisilova, V., et al.
(författare)
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On the fate of oxygenated organic molecules in atmospheric aerosol particles
- 2020
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:11
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Tidskriftsartikel (refereegranskat)abstract
- Highly oxygenated organic molecules (HOMs) are formed from the oxidation of biogenic and anthropogenic gases and affect Earth's climate and air quality by their key role in particle formation and growth. While the formation of these molecules in the gas phase has been extensively studied, the complexity of organic aerosol (OA) and lack of suitable measurement techniques have hindered the investigation of their fate post-condensation, although further reactions have been proposed. We report here novel real-time measurements of these species in the particle phase, achieved using our recently developed extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF). Our results reveal that condensed-phase reactions rapidly alter OA composition and the contribution of HOMs to the particle mass. In consequence, the atmospheric fate of HOMs cannot be described solely in terms of volatility, but particle-phase reactions must be considered to describe HOM effects on the overall particle life cycle and global carbon budget.
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