| 1. |
- Yttri, K. E., et al.
(författare)
-
Source apportionment of the summer time carbonaceous aerosol at Nordic rural background sites
- 2011
-
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:24, s. 13339-13357
-
Tidskriftsartikel (refereegranskat)abstract
- In the present study, natural and anthropogenic sources of particulate organic carbon (OCp) and elemental carbon (EC) have been quantified based on weekly filter samples of PM10 (particles with aerodynamic diameter
|
|
| 2. |
- Hansen, A. M. K., et al.
(författare)
-
Organosulfates and organic acids in Arctic aerosols : speciation, annual variation and concentration levels
- 2014
-
Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:15, s. 7807-7823
-
Tidskriftsartikel (refereegranskat)abstract
- Sources, composition and occurrence of secondary organic aerosols in the Arctic were investigated at Zeppelin Mountain, Svalbard, and Station Nord, northeastern Greenland, during the full annual cycle of 2008 and 2010, respectively. Speciation of organic acids, organosulfates and nitrooxy organosulfates - from both anthropogenic and biogenic precursors were in focus. A total of 11 organic acids (terpenylic acid, benzoic acid, phthalic acid, pinic acid, suberic acid, azelaic acid, adipic acid, pimelic acid, pinonic acid, diaterpenylic acid acetate and 3-methyl-1,2,3-butanetricarboxylic acid), 12 organosulfates and 1 nitrooxy organosulfate were identified in aerosol samples from the two sites using a high-performance liquid chromatograph (HPLC) coupled to a quadrupole Time-of-Flight mass spectrometer. At Station Nord, compound concentrations followed a distinct annual pattern, where high mean concentrations of organosulfates (47 +/- 14 ng m(-3)) and organic acids (11.5 +/- 4 ng m(-3)) were observed in January, February and March, contrary to considerably lower mean concentrations of organosulfates (2 +/- 3 ng m(3-)) and organic acids (2.2 +/- 1 ng m(-3)) observed during the rest of the year. At Zeppelin Mountain, organosulfate and organic acid concentrations remained relatively constant during most of the year at a mean concentration of 15 +/- 4 ng m(-3) and 3.9 +/- 1 ng m(-3), respectively. However during four weeks of spring, remarkably higher concentrations of total organosulfates (23-36 ng m(-3)) and total organic acids (7-10 ngm(-3)) were observed. Elevated organosulfate and organic acid concentrations coincided with the Arctic haze period at both stations, where northern Eurasia was identified as the main source region. Air mass transport from northern Eurasia to Zeppelin Mountain was associated with a 100% increase in the number of detected organosulfate species compared with periods of air mass transport from the Arctic Ocean, Scandinavia and Greenland. The results from this study suggested that the presence of organic acids and organosulfates at Station Nord was mainly due to long-range transport, whereas indications of local sources were found for some compounds at Zeppelin Mountain. Furthermore, organosulfates contributed significantly to organic matter throughout the year at Zeppelin Mountain (annual mean of 13 +/- 8 %) and during Arctic haze at Station Nord (7 +/- 2 %), suggesting organosulfates to be important compounds in Arctic aerosols.
|
|
| 3. |
- Emanuelsson, Eva U., et al.
(författare)
-
Formation of anthropogenic secondary organic aerosol (SOA) and its influence on biogenic SOA properties
- 2012
-
Ingår i: Atmospheric Chemistry and Physics Discussions. - : Copernicus Publications. - 1680-7367 .- 1680-7375. ; 12:8, s. 20311-20350
-
Tidskriftsartikel (refereegranskat)abstract
- Secondary organic aerosol (SOA) formation from mixed anthropogenic and biogenic precursors has been studied exposing reaction mixtures to natural sunlight in the SAPHIR chamber in Jülich, Germany. Several experiments with exclusively anthro- 5 pogenic precursors were performed to establish a relationship between yield and organic aerosol mass loading for the atmospheric relevant range of aerosol loads of 0.01 to 10 μgm−3. The yields (0.5–9 %) were comparable to previous data and further used for the detailed evaluation of the mixed biogenic and anthropogenic experiments. For the mixed experiments a number of different oxidation schemes were addressed. The 10 reactivity, the sequence of addition, and the amount of the precursors influenced the SOA properties. Monoterpene oxidation products, including carboxylic acids and dimer esters were identified in the aged aerosol at levels comparable to ambient air. OH radicals were measured by Laser Induced Fluorescence, which allowed for establishing relations of aerosol properties and composition to the experimental OH dose. Further 15 more, the OH measurements in combination with the derived yields for anthropogenic SOA enabled application of a simplified model to calculate the chemical turnover of the anthropogenic precursor and corresponding anthropogenic contribution to the mixed aerosol. The estimated anthropogenic contributions were ranging from small (8 %) up to significant fraction (>50 %) providing a suitable range to study the effect of aerosol 20 composition on the aerosol volatility (volume fraction remaining at 343 K: 0.86–0.94). The anthropogenic aerosol had higher oxygen to carbon ratio O/C and was less volatile than the biogenic fraction. However, in order to produce significant amount of anthropogenic SOA the reaction mixtures needed a higher OH dose that also increased O/C and provided a less volatile aerosol. A strong positive correlation was found between 25 changes in volatility and O/C with the exception during dark hours where the SOA volatility decreased while O/C did not change significantly. This change in volatility under dark conditions is likely due to chemical or morphological changes not affecting O/C.
|
|
| 4. |
- Emanuelsson, Eva U., et al.
(författare)
-
Formation of anthropogenic secondary organic aerosol (SOA) and its influence on biogenic SOA properties
- 2013
-
Ingår i: Atmos. Chem. Phys.. - : Copernicus Publications. - 1680-7324. ; 13:5, s. 2837-2855
-
Tidskriftsartikel (refereegranskat)abstract
- Secondary organic aerosol (SOA) formation from mixed anthropogenic and biogenic precursors has been studied exposing reaction mixtures to natural sunlight in the SAPHIR chamber in Jülich, Germany. In this study aromatic compounds served as examples of anthropogenic volatile organic compound (VOC) and a mixture of α-pinene and limonene as an example for biogenic VOC. Several experiments with exclusively aromatic precursors were performed to establish a relationship between yield and organic aerosol mass loading for the atmospheric relevant range of aerosol loads of 0.01 to 10 μg m−3. The yields (0.5 to 9%) were comparable to previous data and further used for the detailed evaluation of the mixed biogenic and anthropogenic experiments. For the mixed experiments a number of different oxidation schemes were addressed. The reactivity, the sequence of addition, and the amount of the precursors influenced the SOA properties. Monoterpene oxidation products, including carboxylic acids and dimer esters were identified in the aged aerosol at levels comparable to ambient air. OH radicals were measured by Laser Induced Fluorescence, which allowed for establishing relations of aerosol properties and composition to the experimental OH dose. Furthermore, the OH measurements in combination with the derived yields for aromatic SOA enabled application of a simplified model to calculate the chemical turnover of the aromatic precursor and corresponding anthropogenic contribution to the mixed aerosol. The estimated anthropogenic contributions were ranging from small (≈8%) up to significant fraction (>50%) providing a suitable range to study the effect of aerosol composition on the aerosol volatility (volume fraction remaining (VFR) at 343 K: 0.86–0.94). The aromatic aerosol had higher oxygen to carbon ratio O/C and was less volatile than the biogenic fraction. However, in order to produce significant amount of aromatic SOA the reaction mixtures needed a higher OH dose that also increased O/C and provided a less volatile aerosol. The SOA yields, O/C, and f44 (the mass fraction of CO2+ ions in the mass spectra which can be considered as a measure of carboxylic groups) in the mixed photo-chemical experiments could be described as linear combinations of the corresponding properties of the pure systems. For VFR there was in addition an enhancement effect, making the mixed aerosol significantly less volatile than what could be predicted from the pure systems. A strong positive correlation was found between changes in volatility and O/C with the exception during dark hours where the SOA volatility decreased while O/C did not change significantly. Thus, this change in volatility under dark conditions as well as the anthropogenic enhancement is due to chemical or morphological changes not affecting O/C.
|
|
| 5. |
- Kivekäs, Niku, et al.
(författare)
-
Contribution of ship traffic to aerosol particle concentrations downwind of a major shipping lane
- 2014
-
Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:16, s. 8255-8267
-
Tidskriftsartikel (refereegranskat)abstract
- Particles in the atmosphere are of concern due to their toxic properties and effects on climate. In coastal areas, ship emissions can be a significant anthropogenic source. In this study we investigated the contribution from ship emissions to the total particle number and mass concentrations at a remote location. We studied the particle number concentration (12 to 490 nm in diameter), the mass concentration (12 to 150 nm in diameter) and number and volume size distribution of aerosol particles in ship plumes for a period of 4.5 months at Hovsore, a coastal site on the western coast of Jutland in Denmark. During episodes of western winds, the site is about 50 km downwind of a major shipping lane and the plumes are approximately 1 hour old when they arrive at the site. We have used a sliding percentile-based method for separating the plumes from the measured background values and to calculate the ship plume contribution to the total particle number and PM0.15 mass concentration (mass of particles below 150 nm in diameter, converted from volume assuming sphericity) at the site. The method is not limited to particle number or volume concentration, but can also be used for different chemical species in both particle and gas phase. The total number of analyzed ship plumes was 726, covering on average 19% of the time when air masses were arriving at the site over the shipping lane. During the periods when plumes were present, the particle concentration exceeded the background values on average by 790 cm(-3) by number and 0.10 gm(-3) by mass. The corresponding daily average values were 170 cm-3 and 0.023 gm-3, respectively. This means that the ship plumes contributed between 11 and 19% to the particle number concentration and between 9 and 18% to PM0.15 during days when air was arriving over the shipping lane. The estimated annual contribution from ship plumes, where all wind directions were included, was in the range of 5-8% in particle number concentration and 4-8% in PM0.15.
|
|
