scholarly journals Volatility and hygroscopicity of aging secondary organic aerosol in a smog chamber

2011 ◽  
Vol 11 (22) ◽  
pp. 11477-11496 ◽  
Author(s):  
T. Tritscher ◽  
J. Dommen ◽  
P. F. DeCarlo ◽  
M. Gysel ◽  
P. B. Barmet ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Volume Fraction ◽  
Chemical Characterization ◽  
Mass Gain ◽  
Heterogeneous Reactions ◽  
Oh Radicals ◽  
Smog Chamber ◽  
Chemical Aging ◽  
Aerosol Mass ◽  
Significant Mass

Abstract. The evolution of secondary organic aerosols (SOA) during (photo-)chemical aging processes was investigated in a smog chamber. Fresh SOA from ozonolysis of 10 to 40 ppb α-pinene was formed followed by aging with OH radicals. The particles' volatility and hygroscopicity (expressed as volume fraction remaining (VFR) and hygroscopicity parameter κ) were measured in parallel with a volatility and hygroscopicity tandem differential mobility analyzer (V/H-TDMA). An aerosol mass spectrometer (AMS) was used for the chemical characterization of the aerosol. These measurements were used as sensitive parameters to reveal the mechanisms possibly responsible for the changes in the SOA composition during aging. A change of VFR and/or κ during processing of atmospheric aerosols may occur either by addition of SOA mass (by condensation) or by a change of SOA composition leading to different aerosol properties. The latter may occur either by heterogeneous reactions on the surface of the SOA particles, by condensed phase reactions like oligomerization or by an evaporation – gas-phase oxidation – recondensation cycle. The condensation mechanism showed to be dominant when there is a substantial change in the aerosol mass by addition of new molecules to the aerosol phase with time. Experiments could be divided into four periods based on the temporal evolution (qualitative changes) of VFR, κ and organic mass: O3 induced condensation, ripening, and OH induced chemical aging first with substantial mass gain and then without significant mass gain. During the O3 induced condensation the particles' volatility decreased (increasing VFR) while the hygroscopicity increased. Thereafter, in the course of ripening volatility continued to decrease, but hygroscopicity stayed roughly constant. After exposing the SOA to OH radicals an OH induced chemical aging with substantial mass gain started resulting in the production of at least 50 % more SOA mass. This new SOA mass was highly volatile and oxidized. This period was then followed by further OH induced chemical aging without significant mass gain leading to a decrease of volatility while hygroscopicity and SOA mass stayed roughly constant.

scholarly journals Volatility and hygroscopicity of aging secondary organic aerosol in a smog chamber

2011 ◽  
Vol 11 (3) ◽  
pp. 7423-7467 ◽  
Author(s):  
T. Tritscher ◽  
J. Dommen ◽  
P. F. DeCarlo ◽  
P. B. Barmet ◽  
A. P. Praplan ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Physical Parameters ◽  
Oh Radicals ◽  
Smog Chamber ◽  
Chemical Aging ◽  
Aerosol Mass ◽  
Gas Phase Oxidation ◽  
Substantial Change

Abstract. The evolution of secondary organic aerosols (SOA) during (photo-)chemical aging processes was investigated in a smog chamber. SOA from 10–40 ppb α-pinene was formed during ozonolysis followed by aging with OH radicals. The particles' volatility and hygroscopicity (expressed as volume fraction remaining (VFR) and hygroscopicity parameter κ) were measured with a volatility and hygroscopicity tandem differential mobility analyzer (V/H-TDMA). These measurements were used as sensitive physical parameters to reveal the possible mechanisms responsible for the chemical changes in the SOA composition during aging: A change of VFR and/or κ during processing of atmospheric aerosol may occur either by addition of SOA mass (by condensation) or by an exchange of molecules in the SOA by other molecules with different properties. The former process increases the SOA mass by definition, while the latter keeps the SOA mass roughly constant and may occur either by heterogeneous reactions on the surface of the SOA particles, by homogeneous reactions like oligomerization or by an evaporation – gas-phase oxidation – recondensation cycle. Thus, when there is a substantial change in the aerosol mass with time, the condensation mechanism may be assumed to be dominant, while, when the mass stays roughly constant the exchange mechanism is likely to be dominant, a process termed ripening here. Depending on the phase of the experiment, an O3 mediated condensation, O3 mediated ripening, OH mediated condensation, and OH mediated ripening could be distinguished. During the O3 mediated condensation the particles volatility decreased (increasing VFR) while the hygroscopicity increased. Thereafter, in the course of O3 mediated ripening volatility continued to decrease, but hygroscopicity stayed roughly constant. After exposing the SOA to OH radicals an OH mediated condensation started with a significant increase of SOA mass. Concurrently, hygroscopicity and volatility increased. This phase was then followed by an OH mediated ripening with a decrease of volatility.

scholarly journals Constraining condensed-phase formation kinetics of secondary organic aerosol components from isoprene epoxydiols

2016 ◽  
Vol 16 (3) ◽  
pp. 1245-1254 ◽  
Author(s):  
T. P. Riedel ◽  
Y.-H. Lin ◽  
Z. Zhang ◽  
K. Chu ◽  
J. A. Thornton ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Rate Constants ◽  
Reaction Rate ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Model Calculations ◽  
Reaction Rate Constants ◽  
Aerosol Mass

Abstract. Isomeric epoxydiols from isoprene photooxidation (IEPOX) have been shown to produce substantial amounts of secondary organic aerosol (SOA) mass and are therefore considered a major isoprene-derived SOA precursor. Heterogeneous reactions of IEPOX on atmospheric aerosols form various aerosol-phase components or "tracers" that contribute to the SOA mass burden. A limited number of the reaction rate constants for these acid-catalyzed aqueous-phase tracer formation reactions have been constrained through bulk laboratory measurements. We have designed a chemical box model with multiple experimental constraints to explicitly simulate gas- and aqueous-phase reactions during chamber experiments of SOA growth from IEPOX uptake onto acidic sulfate aerosol. The model is constrained by measurements of the IEPOX reactive uptake coefficient, IEPOX and aerosol chamber wall losses, chamber-measured aerosol mass and surface area concentrations, aerosol thermodynamic model calculations, and offline filter-based measurements of SOA tracers. By requiring the model output to match the SOA growth and offline filter measurements collected during the chamber experiments, we derive estimates of the tracer formation reaction rate constants that have not yet been measured or estimated for bulk solutions.

scholarly journals Constraining condensed-phase formation kinetics of secondary organic aerosol components from isoprene epoxydiols

2015 ◽  
Vol 15 (20) ◽  
pp. 28289-28316 ◽  
Author(s):  
T. P. Riedel ◽  
Y.-H. Lin ◽  
Z. Zhang ◽  
K. Chu ◽  
J. A. Thornton ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Rate Constants ◽  
Reaction Rate ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Model Calculations ◽  
Reaction Rate Constants ◽  
Aerosol Mass

Abstract. Isomeric epoxydiols from isoprene photooxidation (IEPOX) have been shown to produce substantial amounts of secondary organic aerosol (SOA) mass and are therefore considered a major isoprene-derived SOA precursor. Heterogeneous reactions of IEPOX on atmospheric aerosols form various aerosol-phase components or "tracers" that contribute to the SOA mass burden. A limited number of the reaction rate constants for these acid-catalyzed aqueous-phase tracer formation reactions have been constrained through bulk laboratory measurements. We have designed a chemical box model with multiple experimental constraints to explicitly simulate gas- and aqueous-phase reactions during chamber experiments of SOA growth from IEPOX uptake onto acidic sulfate aerosol. The model is constrained by measurements of the IEPOX reactive uptake coefficient, IEPOX and aerosol chamber wall-losses, chamber-measured aerosol mass and surface area concentrations, aerosol thermodynamic model calculations, and offline filter-based measurements of SOA tracers. By requiring the model output to match the SOA growth and offline filter measurements collected during the chamber experiments, we derive estimates of the tracer formation reaction rate constants that have not yet been measured or estimated for bulk solutions.

scholarly journals Chemical characterization of the main products formed through aqueous-phase photonitration of guaiacol

2014 ◽  
Vol 7 (8) ◽  
pp. 2457-2470 ◽  
Author(s):  
Z. Kitanovski ◽  
A. Čusak ◽  
I. Grgić ◽  
M. Claeys
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
High Performance ◽  
Solid Phase ◽  
Chemical Characterization ◽  
Heterogeneous Reactions ◽  
Negative Ion ◽  
Reaction Products ◽  
Esi Ms

Abstract. Guaiacol (2-methoxyphenol) and its derivatives can be emitted into the atmosphere by thermal degradation (i.e., burning) of wood lignins. Due to its volatility, guaiacol is predominantly distributed atmospherically in the gaseous phase. Recent studies have shown the importance of aqueous-phase reactions in addition to the dominant gas-phase and heterogeneous reactions of guaiacol, in the formation of secondary organic aerosol (SOA) in the atmosphere. The main objectives of the present study were to chemically characterize the main products of the aqueous-phase photonitration of guaiacol and examine their possible presence in urban atmospheric aerosols. The aqueous-phase reactions were carried out under simulated sunlight and in the presence of hydrogen peroxide and nitrite. The formed guaiacol reaction products were concentrated by solid-phase extraction and then purified with semi-preparative high-performance liquid chromatography (HPLC). The fractionated individual compounds were isolated as pure solids and further analyzed with liquid-state proton, carbon-13 and two-dimensional nuclear magnetic resonance (NMR) spectroscopy, and direct infusion negative ion electrospray ionization tandem mass spectrometry ((−)ESI-MS/MS). The NMR and product ion (MS2) spectra were used for unambiguous product structure elucidation. The main products of guaiacol photonitration are 4-nitroguaiacol (4NG), 6-nitroguaiacol (6NG), and 4,6-dinitroguaiacol (4,6DNG). Using the isolated compounds as standards, 4NG and 4,6DNG were unambiguously identified in winter PM10 aerosols from the city of Ljubljana (Slovenia) by means of HPLC/(−)ESI-MS/MS. Owing to the strong absorption of ultraviolet and visible light, 4,6DNG could be an important constituent of atmospheric "brown" carbon, especially in regions affected by biomass burning.

scholarly journals Burning of olive tree branches: a major organic aerosol source in the Mediterranean

2013 ◽  
Vol 13 (17) ◽  
pp. 8797-8811 ◽  
Author(s):  
E. Kostenidou ◽  
C. Kaltsonoudis ◽  
M. Tsiflikiotou ◽  
E. Louvaris ◽  
L. M. Russell ◽  
...  
Keyword(s):  
Mass Spectrum ◽  
Olive Tree ◽  
Organic Aerosol ◽  
Oh Radicals ◽  
Smog Chamber ◽  
Chemical Aging ◽  
Mediterranean Countries ◽  
Fine Aerosol ◽  
Benzene Toluene ◽  
Ambient Measurements

Abstract. Aerosol produced during the burning of olive tree branches was characterized with both direct source sampling (using a mobile smog chamber) and with ambient measurements during the burning season. The fresh particles were composed of 80% organic matter, 8–10% black carbon (BC), 5% potassium, 3–4% sulfate, 2–3% nitrate and 0.8% chloride. Almost half of the fresh olive tree branches burning organic aerosol (otBB-OA) consisted of alkane groups. Their mode diameter was close to 70 nm. The oxygen to carbon (O : C) ratio of the fresh otBB-OA was 0.29 ± 0.04. The mass fraction of levoglucosan in PM1 was 0.034–0.043, relatively low in comparison with most fuel types. This may lead to an underestimation of the otBB-OA contribution if levoglucosan is being used as a wood burning tracer. Chemical aging was observed during smog chamber experiments, as f44 and O : C ratio increased, due to reactions with OH radicals and O3. The otBB-OA AMS mass spectrum differs from the other published biomass burning spectra, with a main difference at m/z 60, used as levoglucosan tracer. In addition to particles, volatile organic compounds (VOCs) such as methanol, acetonitrile, acrolein, benzene, toluene and xylenes are also emitted. Positive matrix factorization (PMF) was applied to the ambient organic aerosol data and 3 factors could be identified: OOA (oxygenated organic aerosol, 55%), HOA (hydrocarbon-like organic aerosol, 11.3%) and otBB-OA 33.7%. The fresh chamber otBB-OA AMS spectrum is close to the PMF otBB-OA spectrum and resembles the ambient mass spectrum during olive tree branches burning periods. We estimated an otBB-OA emission factor of 3.5 ± 0.9 g kg−1. Assuming that half of the olive tree branches pruned is burned in Greece, 2300 ± 600 tons of otBB-OA are emitted every year. This activity is one of the most important fine aerosol sources during the winter months in Mediterranean countries.

scholarly journals Burning of olive tree branches: a major organic aerosol source in the Mediterranean

2013 ◽  
Vol 13 (3) ◽  
pp. 7223-7266 ◽  
Author(s):  
E. Kostenidou ◽  
C. Kaltsonoudis ◽  
M. Tsiflikiotou ◽  
E. Louvaris ◽  
L. M. Russell ◽  
...  
Keyword(s):  
Mass Spectrum ◽  
Olive Tree ◽  
Organic Aerosol ◽  
Oh Radicals ◽  
Smog Chamber ◽  
Chemical Aging ◽  
Mediterranean Countries ◽  
Fine Aerosol ◽  
Benzene Toluene ◽  
The Mediterranean

Abstract. Aerosol produced during the burning of olive tree branches was characterized with both direct source-sampling (using a mobile smog chamber) and with ambient measurements during the burning season. The fresh particles were composed of 80% organic matter, 8–10% black carbon (BC), 5% potassium, 3–4% sulfate, 2–3% nitrate and 0.8% chloride. Almost half of the fresh olive tree branches burning organic aerosol (otBB-OA) consisted of alkane groups. Their mode diameter was close to 70 nm. The oxygen to carbon (O:C) ratio of the fresh otBB-OA was 0.29 ± 0.04. The mass fraction of levoglucosan in PM1 was 0.034–0.043, relatively low in comparison with most fuel types. This may lead to an underestimation of the otBB-OA contribution if levoglucosan is being used as a wood burning tracer. Chemical aging was observed during smog chamber experiments, as f44 and O:C ratio increased, due to reactions with OH radicals and O3. The otBB-OA AMS mass spectrum differs from the other published biomass burning spectra, with a main difference at m/z 60, used as levoglucosan tracer. In addition to particles, volatile organic compounds (VOCs) such as methanol, acetonitrile, acrolein, benzene, toluene and xylenes are also emitted. Positive matrix factorization (PMF) was applied to the ambient organic aerosol data and 3 factors could be identified: OOA (oxygenated organic aerosol, 55%), HOA (hydrocarbon-like organic aerosol, 11.3%) and otBB-OA 33.7%. The fresh chamber otBB-OA AMS spectrum is close to the PMF otBB-OA spectrum and resembles the ambient mass spectrum during olive tree branches burning periods. We estimated an otBB-OA emission factor of 3.5 ± 0.2 g kg−1. Assuming that half of the olive tree branches pruned is burned in Greece 2280 ± 140 tons of otBB-OA are emitted every year. This activity is one of the most important fine aerosol sources during the winter months in the Mediterranean countries.

scholarly journals Secondary organic aerosol formation from biomass burning emissions

2019 ◽  
Author(s):  
Christopher Y. Lim ◽  
David H. Hagan ◽  
Matthew M. Coggon ◽  
Abigail R. Koss ◽  
Kanako Sekimoto ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Secondary Organic Aerosol ◽  
Total Concentration ◽  
Organic Aerosol ◽  
Oh Radicals ◽  
Aerosol Formation ◽  
Atmospheric Aging ◽  
Aerosol Mass ◽  
Photochemical Aging ◽  
Organic Gases

Abstract. Biomass burning is an important source of aerosol and trace gases to the atmosphere, but how these emissions change chemically during their lifetimes is not fully understood. As part of the Fire Influence on Regional and Global Environments Experiment (FIREX 2016), we investigated the effect of photochemical aging on biomass burning organic aerosol (BBOA), with a focus on fuels from the western United States. Emissions were sampled into a small (150 L) environmental chamber and photochemically aged via the addition of ozone and irradiation by 254 nm light. While some fraction of species undergoes photolysis, the vast majority of aging occurs via reaction with OH radicals, with total OH exposures corresponding to the equivalent of up to 10 days of atmospheric oxidation. For all fuels burned, large and rapid changes are seen in the ensemble chemical composition of BBOA, as measured by an aerosol mass spectrometer (AMS). Secondary organic aerosol (SOA) formation is seen for all aging experiments and continues to grow with increasing OH exposure, but the magnitude of the SOA formation is highly variable between experiments. This variability can be explained well by a combination of experiment-to-experiment differences in OH exposure and the total concentration of non-methane organic gases (NMOGs) in the chamber before oxidation, measured by PTR-ToF-MS (r2 values from 0.64 to 0.83). From this relationship, we calculate the fraction of carbon from biomass burning NMOGs that is converted to SOA as a function of equivalent atmospheric aging time, with carbon yields ranging from 24 ± 4 % after 6 hours to 56 ± 9 % after 4 days.

scholarly journals Regional and local variations in atmospheric aerosols using ground-based sun photometry during Distributed Regional Aerosol Gridded Observation Networks (DRAGON) in 2012

2016 ◽  
Vol 16 (22) ◽  
pp. 14795-14803 ◽  
Author(s):  
Itaru Sano ◽  
Sonoyo Mukai ◽  
Makiko Nakata ◽  
Brent N. Holben
Keyword(s):  
Atmospheric Aerosols ◽  
Urban Areas ◽  
Regional Scale ◽  
Reanalysis Data ◽  
Aerosol Dynamics ◽  
Aerosol Mass ◽  
Combined Use ◽  
Environmental Prediction ◽  
Almost All ◽  
Observation Networks

Abstract. Aerosol mass concentrations are affected by local emissions as well as long-range transboundary (LRT) aerosols. This work investigates regional and local variations of aerosols based on Distributed Regional Aerosol Gridded Observation Networks (DRAGON). We constructed DRAGON-Japan and DRAGON-Osaka in spring of 2012. The former network covers almost all of Japan in order to obtain aerosol information in regional scale over Japanese islands. It was determined from the DRAGON-Japan campaign that the values of aerosol optical thickness (AOT) decrease from west to east during an aerosol episode. In fact, the highest AOT was recorded at Fukue Island at the western end of the network, and the value was much higher than that of urban areas. The latter network (DRAGON-Osaka) was set as a dense instrument network in the megalopolis of Osaka, with a population of 12 million, to better understand local aerosol dynamics in urban areas. AOT was further measured with a mobile sun photometer attached to a car. This transect information showed that aerosol concentrations rapidly changed in time and space together when most of the Osaka area was covered with moderate LRT aerosols. The combined use of the dense instrument network (DRAGON-Osaka) and high-frequency measurements provides the motion of aerosol advection, which coincides with the wind vector around the layer between 700 and 850 hPa as provided by the reanalysis data of the National Centers for Environmental Prediction (NCEP).

scholarly journals Particulate organic nitrates observed in an oil and natural gas production region during wintertime

2015 ◽  
Vol 15 (16) ◽  
pp. 9313-9325 ◽  
Author(s):  
L. Lee ◽  
P. J. Wooldridge ◽  
J. deGouw ◽  
S. S. Brown ◽  
T. S. Bates ◽  
...  
Keyword(s):  
Field Measurements ◽  
Atomic Ratio ◽  
Gas Production ◽  
Heterogeneous Reactions ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Production Region ◽  
Aerosol Mass ◽  
Oil And Natural Gas ◽  
Aerosol Volume

Abstract. Organic nitrates in both gas and condensed (aerosol) phases were measured during the Uintah Basin Winter Ozone Study from January to February in 2012. A high degree of correlation between total aerosol volume at diameters less than 500 nm and the particulate organic nitrate concentration indicates that organic nitrates are a consistent, if not dominant, fraction of fine aerosol mass. In contrast, a similar correlation with sub-2.5 μm aerosol volume is weaker. The C : N atomic ratio inferred from field measurements of PM2.5 and particulate organic nitrate is 34 : 1. Calculations constrained by the observations indicate that both condensation of gas-phase nitrates and heterogeneous reactions of NO3 / N2O5 are responsible for introducing organic nitrate functionality into the aerosol and that the source molecules are alkanes. Extrapolating the results to urban aerosol suggests organic nitrate production from alkanes may be a major secondary organic aerosol source.

scholarly journals Chemical characterization of fine particular matter in Changzhou, China and source apportionment with offline aerosol mass spectrometry

2016 ◽  
Author(s):  
Zhaolian Ye ◽  
Jiashu Liu ◽  
Aijun Gu ◽  
Feifei Feng ◽  
Yuhai Liu ◽  
...  
Keyword(s):  
Trace Elements ◽  
Organic Matter ◽  
Organic Carbon ◽  
Source Apportionment ◽  
Major Ions ◽  
Chemical Properties ◽  
Chemical Characterization ◽  
Water Soluble ◽  
Traffic Emissions ◽  
Aerosol Mass

Abstract. Knowledge on aerosol chemistry in densely populated regions is critical for reduction of air pollution, while such studies haven't been conducted in Changzhou, an important manufacturing base and polluted city in the Yangtze River Delta (YRD), China. This work, for the first time, performed a thorough chemical characterization on the fine particular matter (PM2.5) samples, collected during July 2015 to April 2016 across four seasons in Changzhou city. A suite of analytical techniques were employed to characterize organic carbon / elemental carbon (OC / EC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSIIs), trace elements, and polycyclic aromatic hydrocarbons (PAHs) in PM2.5; in particular, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was deployed to probe the chemical properties of water-soluble organic aerosols (WSOA). The average PM2.5 concentrations were found to be 108.3 μg m−3, and all identified species were able to reconstruct ~ 80 % of the PM2.5 mass. The WSIIs occupied about half of the PM2.5 mass (~ 52.1 %), with SO42−, NO3− and NH4+ as the major ions. On average, nitrate concentrations dominated over sulfate (mass ratio of 1.21), indicating influences from traffic emissions. OC and EC correlated well with each other and the highest OC / EC ratio (5.16) occurred in winter, suggesting complex OC sources likely including both secondarily formed and primarily emitted OA. Concentrations of eight trace elements (Mn, Zn, Al, B, Cr, Cu, Fe, Pb) can contribute up to 6.0 % of PM2.5 during winter. PAHs concentrations were also high in winter (140.25 ng m−3), which were predominated by median/high molecular weight PAHs with 5- and 6-rings. The organic matter including both water-soluble and water-insoluble species occupied ~ 20 % PM2.5 mass. SP-AMS determined that the WSOA had an average atomic oxygen-to-carbon (O / C), hydrogen-to-carbon (H / C), nitrogen-to-carbon (N / C) and organic matter-to-organic carbon (OM / OC) ratios of 0.36, 1.54, 0.11, and 1.74, respectively. Source apportionment of WSOA further identified two secondary OA (SOA) factors (a less oxidized and a more oxidized OA) and two primary OA (POA) factors (a nitrogen enriched hydrocarbon-like traffic OA and a cooking-related OA). On average, the POA contribution overweighed SOA (55 % vs. 45 %), indicating the important role of local anthropogenic emissions to the aerosol pollution in Changzhou. Our measurement also shows the abundance of organic nitrogen species in WSOA, and the source analyses suggest these species likely associated with traffic emissions, which warrants more investigations on PM samples from other locations.

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