The study investigates the sources of fine organic aerosol (OA) in the boreal forest, based on measurements including both filter sampling (PM1) and online methods and carried out during a one-month ...campaign held in Hyytiälä, Finland, in spring 2007. Two aerosol mass spectrometers (Q-AMS, ToF-AMS) were employed to measure on-line concentrations of major non-refractory aerosol species, while the water extracts of the filter samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy for organic functional group characterization of the polar organic fraction of the aerosol. AMS and NMR spectra were processed separately by non-negative factorization algorithms, in order to apportion the main components underlying the submicrometer organic aerosol composition and depict them in terms of both mass fragmentation patterns and functional group compositions. The NMR results supported the AMS speciation of oxidized organic aerosol (OOA) into two main fractions, which could be generally labelled as more and less oxidized organics. The more oxidized component was characterized by a mass spectrum dominated by the m/z 44 peak, and in parallel by a NMR spectrum showing aromatic and aliphatic backbones highly substituted with oxygenated functional groups (carbonyls/carboxyls and hydroxyls). Such component, contributing on average 50% of the OA mass throughout the observing period, was associated with pollution outbreaks from the Central Europe. The less oxidized component was enhanced in concomitance with air masses originating from the North-to-West sector, in agreement with previous investigations conducted at this site. NMR factor analysis was able to separate two distinct components under the less oxidized fraction of OA. One of these NMR-factors was associated with the formation of terrestrial biogenic secondary organic aerosol (BSOA), based on the comparison with spectral profiles obtained from laboratory experiments of terpenes photo-oxidation. The second NMR factor associated with western air masses was linked to biogenic marine sources, and was enriched in low-molecular weight aliphatic amines. Such findings provide evidence of at least two independent sources originating biogenic organic aerosols in Hyytiälä by oxidation and condensation mechanisms: reactive terpenes emitted by the boreal forest and compounds of marine origin, with the latter relatively more important when predominantly polar air masses reach the site. This study is an example of how spectroscopic techniques, such as proton NMR, can add functional group specificity for certain chemical features (like aromatics) of OA with respect to AMS. They can therefore be profitably exploited to complement aerosol mass spectrometric measurements in organic source apportionment studies.
The study investigates the sources of fine organic aerosol (OA) in the boreal forest, based on measurements including both filter sampling (PM1) and online methods and carried out during a one-month ...campaign held in Hyytiälä, Finland, in spring 2007. Two aerosol mass spectrometers (Q-AMS, ToF-AMS) were employed to measure on-line air mass concentrations of major non-refractory aerosol species, while the water extracts of the filter samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy for organic functional group characterization of the polar organic fraction of the aerosol. AMS and NMR spectra were processed separately by non-negative factorization algorithms, in order to apportion the main components underlying the submicrometer organic aerosol composition and depict them in terms of both mass fragmentation patterns and functional group compositions. The NMR results supported the AMS speciation of oxidized organic aerosol (OOA) into two main fractions, which could be generally labelled as more and less oxidized organics. The more oxidized component was characterized by a mass spectrum dominated by the m/z 44 peak, and in parallel by a NMR spectrum showing aromatic and aliphatic backbones highly substituted with oxygenated functional groups (carbonyls/carboxyls and hydroxyls). Such component, contributing on average 50 % of the OA mass throughout the observing period, was associated with pollution outbreaks from the Central Europe. The less oxidized component showed features consistent with less oxygenated aerosols and was enhanced in concomitance with air masses originating from the North-to-West sector, in agreement with previous investigations conducted at this site. NMR factor analysis was able to separate two distinct components under the less oxidized fraction of OA. One of these NMR-factors was associated to the formation of terrestrial biogenic secondary organic aerosol (BSOA), based on the comparison with spectral profiles obtained from laboratory experiments of terpenes photo-oxidation. The second NMR factor associated with western air masses was linked to biogenic marine sources, and was enriched in low-molecular weight aliphatic amines. Such findings provide evidence of at least two independent sources mbox{originating} biogenic organic aerosols in Hyytiälä by oxidation and condensation mechanisms: reactive terpenes emitted by the boreal forest and compounds of marine origin, with the latter relatively more important when predominantly polar air masses reach the site. This study is an example of how spectroscopic techniques, such as proton NMR, can add functional group specificity for certain chemical features (like aromatics) of OA with respect to AMS. They can therefore be profitably be exploited to complement aerosol mass spectrometric measurements in organic source apportionment studies.
A measurement site for aerosol-cloud interaction studies is described. The newly established measurement site at Puijo observation tower produces data from semiurban environment for climatic models ...and particle formation studies. In addition to the basic measurements, intensive yearly measurement campaigns are organized at the station. The first aerosol-cloud interaction experiment (PUCE1) took place in October–November 2006. Some results of the measurement campaing are presented and discussed.
Keywords Aerosol-cloud interaction, aerosol mass spectrometry, urban aerosols
Targeting nanoparticles to desired intracellular compartments is a major challenge. Integrin-type adhesion receptors are connected to different endocytosis routes in a receptor-specific manner. ...According to our previous observations, the internalization of an α2β1-integrin-echovirus-1 complex takes place via a macropinocytosis-like mechanism, suggesting that the receptor could be used to target nanoparticles to this specific entry route. Here, silica-based nanoparticles, carrying monoclonal antibodies against the α2β1 integrin as address labels, were synthesized. Studies with flow cytometry, atomic force microscopy and confocal microscopy showed the particles to attach to the cell surface via the α2β1 integrin. Furthermore, quantitative analysis of nanoparticle trafficking inside the cell performed with the BioImageXD software indicated that the particles enter cells via a macropinocytosis-like process and end up in caveolin-1 positive structures. Thus, we suggest that different integrins can guide particles to distinct endocytosis routes and, subsequently, also to specific intracellular compartments. In addition, we show that with the BioImageXD software it is possible to conduct sensitive and complex analyses of the behavior of small fluorescent particles inside cells, using basic confocal microscopy images.
South Africa has the largest industrialised economy in Africa, with significant mining and metallurgical activities. A large fraction of the South African mineral assets is concentrated in the ...Bushveld Igneous Complex (BIC), with the western limb being the most exploited. Compared with South African and European ambient air quality standards, SO sub( 2), NO sub( 2) and CO concentrations were generally acceptable. The major sources of SO sub( 2) were identified as high-stack industry emissions, while household combustion from semi-formal and informal settlements was identified as the predominant source of NO sub( 2) and CO. The main contributing factor was identified to be the influx of regional air masses, with high O sub( 3) precursor concentrations. The main source of PM sub( 10) was identified as household combustion from semi-formal and informal settlements. The findings clearly indicate that atmospheric O sub( 3) and PM sub( 10) levels in the western BIC need to be addressed to avoid negative environmental and human health impacts.
The activity of H-Beta-25, H-Beta-75, H-Y-12, H-Mordenite-20, and H-MCM-41 was investigated in the ring opening of decalin at 498–573 K in the presence of hydrogen. The catalysts activity and ...deactivation were correlated to their acidity determined by FTIR pyridine adsorption, pore structure, and surface area changes. Skeletal isomerization, stereoisomerization, ring opening, and cracking were the prevailing reactions taking place. Skeletal isomerization included several parallel and consecutive reactions resulting in a wide variety of products, which underwent ring opening, and subsequently cracking. Virtually no direct ring opening of decalin was observed; i.e., decalin must first be isomerized to alkyl-substituted bicyclononanes and bicyclooctanes to make possible its ring opening. The main products were grouped according to their structural features to evaluate the product distribution, which was influenced by catalyst acidity and pore structure. The initial activity of the catalysts increased with increasing acidity and reaction temperature, respectively. The deactivation of the investigated catalysts depended on their pore structure; H-Y was deactivated faster than Beta zeolites as it allowed the formation of large hydrocarbon intermediates inside the cavities.
Oxidation flow reactors (OFRs) have been increasingly used to conduct research on secondary aerosol formation potential and composition in laboratory and field studies by exposing aerosols to high ...levels of oxidants in short time periods. In order to assess the atmospheric relevance of the triggered chemical reactions, kinetic models have been developed to reveal the production of atmospheric oxidants and the fate of volatile organic compounds (VOCs). However, it is unknown how different OFR conditions generating the same OH exposure affect the chemical and physical properties of the secondary aerosol particle phase because the model is based on gas phase chemistry. Toluene as a well-investigated precursor of secondary organic aerosols (SOAs) was aged in the high-volume OFR "PEAR" at three different external OH reactivities (OHR
ext
) and in an environmental chamber at the same OH exposure of (1.09 ± 0.09) × 10
11
s cm
−3
. These specific OFR conditions altered the majority of the investigated chemical and physical properties of the toluene-derived SOA (tol-SOA). However, OFR-aging at low OHR
ext
associated with atmospherically relevant conditions did not lead to physical and chemical SOA properties most similar to chamber-generated SOAs at the same low OHR
ext
. Particularly, for the most detailed chemical analysis by electrospray (ESI) high-resolution Orbitrap mass spectrometry (HRMS), tol-SOA from the PEAR at high OHR
ext
, deviating from atmospherically relevant conditions, and the chamber were most different to tol-SOA from the PEAR with low and medium OHR
ext
. Our study challenges the concept of atmospherically relevant OFR aerosol aging and motivates further exploration of OFR conditions on secondary aerosol composition.
Analysis of physical-chemical aerosol properties challenges the concept of atmospherically relevant and irrelevant reactions in oxidation flow reactor chemistry.
Trace metal species emitted into the atmosphere from natural and anthropogenic sources can cause various health-related and environmental problems. Limited data exist for atmospheric trace metal ...concentrations in South Africa, which has the largest industrialised economy in Africa, with significant mining and metallurgical activities. A large fraction of these mineral assets is concentrated in the Bushveld Igneous Complex, with the western limb being the most exploited. To partially address this knowledge gap, atmospheric trace metals were collected in the western Bushveld Igneous Complex at Marikana in the North West Province. Diurnal PM2.5 and PM10 samples were collected for 1 year. A total of 27 trace metal species were determined. With the exception of Ni, none of the trace metals measured during the sampling period exceeded local or international air quality standard limit values. Total trace metal concentrations in the PM10 fraction peaked during the dry months and were regularly washed out during the wet season.
Free Tropospheric Aerosols Over South Africa Elina, Giannakaki; Pfüller, Anne; Korhonen, Kimmo ...
EPJ Web of Conferences,
01/2016, Letnik:
119
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Raman lidar data of one year was been analyzed to obtain information relating aerosol layers in the free troposphere over South Africa, Elandsfontein. In total, 375 layers were observed above the ...boundary layer during the period 30th January 2010 – 31st January 2011. The seasonal behavior of aerosol layer geometrical characteristics as well as intensive and extensive optical properties were studied. In general, layers were observed at higher altitudes during spring (2520 ± 970 m) while the geometrical layer depth did not show any significant seasonal dependence. The variations of most of the intensive and extensive optical properties analyzed were high during all seasons. Layers were observed at mean altitude of 2100 m ± 1000 m with lidar ratio at 355 nm of 67 ± 25 and extinction-related Ångström exponent between 355 and 532 nm of 1.9 ± 0.8.
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