scholarly journals The effect of temperature and water on secondary organic aerosol formation from ozonolysis of limonene, Δ<sup>3</sup>-carene and α-pinene

2008 ◽  
Vol 8 (21) ◽  
pp. 6541-6549 ◽  
Author(s):  
Å. M. Jonsson ◽  
M. Hallquist ◽  
E. Ljungström
Keyword(s):  
Temperature Dependence ◽  
Low Temperatures ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Reaction Rates ◽  
Chemical Mechanism ◽  
Positive Temperature ◽  
Aerosol Formation ◽  
Secondary Chemistry

Abstract. The effect of reaction temperature and how water vapour influences the formation of secondary organic aerosol (SOA) in ozonolysis of limonene, Δ3-carene and α-pinene, both regarding number and mass of particles, has been investigated by using a laminar flow reactor (G-FROST). Experiments with cyclohexane and 2-butanol as OH scavengers were compared to experiments without any scavenger. The reactions were conducted in the temperature range between 298 and 243 K, and at relative humidities between <10 and 80%. Results showed that there is still a scavenger effect on number and mass concentrations at low temperatures between experiments with and without an addition of an OH scavenger. This shows that the OH chemistry is influencing the SOA formation also at these temperatures. The overall temperature dependence on SOA formation is not as strong as expected from partitioning theory. In some cases there is even a positive temperature dependence that must be related to changes in the chemical mechanism and/or reduced rates of secondary chemistry at low temperatures. The precursor's α-pinene and Δ3-carene exhibit a similar temperature dependence regarding both number and mass of particles formed, whereas limonene shows a different dependence. The water effect at low temperature could be explained by physical uptake and cluster stabilisation. At higher temperatures, only a physical explanation is not sufficient and the observations are in line with water changing the chemical mechanism or reaction rates. The data presented adds to the understanding of SOA contribution to new particle formation and atmospheric degradation mechanisms.

scholarly journals The effect of temperature and water on secondary organic aerosol formation from ozonolysis of limonene, Δ³-carene and α-pinene

2008 ◽  
Vol 8 (3) ◽  
pp. 9323-9346 ◽  
Author(s):  
Å. M. Jonsson ◽  
M. Hallquist ◽  
E. Ljungström
Keyword(s):  
Temperature Dependence ◽  
Low Temperatures ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Reaction Rates ◽  
Chemical Mechanism ◽  
Positive Temperature ◽  
Aerosol Formation ◽  
Aerosol Composition ◽  
Secondary Chemistry

Abstract. The effect of reaction temperature and how water vapour influences the formation of secondary organic aerosol (SOA) in ozonolysis of limonene, Δ3-carene and α-pinene, both regarding number and mass of particles, has been investigated by using a laminar flow reactor G-FROST. Experiments with cyclohexane and 2-butanol (~3.5×1014 molecules cm−3) as OH scavengers were compared to experiments without any scavenger. The reactions were conducted in the temperature range between 298 and 243 K, and at relative humidities between <10 and 80%. Results showed that there is still a scavenger effect on number and mass concentrations at low temperatures between experiments with and without OH scavenger. This shows that the OH chemistry is influencing the SOA formation also at these temperatures. The overall temperature dependence on SOA formation is not as strong as expected from the partitioning theory. In some cases there is even a positive temperature dependence that must be related to changes in the chemical mechanism and/or reduced rates of secondary chemistry at low temperatures. The water effect at low temperature could be explained by physical uptake and cluster stabilisation. At higher temperatures, only a physical explanation is not sufficient and the observations are in line with water changing the chemical mechanism or reaction rates. The data presented adds to the understanding of SOA contribution to atmospheric aerosol composition, new particle formation and atmospheric degradation mechanisms.

scholarly journals Temperature dependence of secondary organic aerosol yield from the ozonolysis of β-pinene

2006 ◽  
Vol 6 (5) ◽  
pp. 10275-10297 ◽  
Author(s):  
C. Stenby ◽  
U. Pöschl ◽  
P. von Hessberg ◽  
M. Bilde ◽  
O. J. Nielsen ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Gas Phase ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Measurement Data ◽  
Organic Aerosol ◽  
Reaction Products ◽  
Aerosol Formation ◽  
Product Model ◽  
High Particle

Abstract. The temperature dependence of secondary organic aerosol (SOA) formation from ozonolysis of β-pinene was studied in a flow reactor at 263–303 K and 1007 hPa. The observed SOA yields were of similar magnitude as predicted by a two-product model based on detailed gas phase chemistry (Jenkin, 2004), reaching maximum values of 0.22–0.39 at high particle mass concentrations. However, the measurement data exhibited significant deviations (up to 50%) from the predicted linear dependence on inverse temperature. When fitting the measurement data with a two-product model, we found that both the partitioning coefficients (Kom,i) and the stoichiometric yields (αi) of the low-volatile and semi-volatile species vary with temperature. The results indicate that not only the reaction product vapour pressures but also the relative contributions of different gas-phase or multiphase reaction channels are dependent on temperature. We suggest that the modelling of secondary organic aerosol formation in the atmosphere needs to take into account the effects of temperature on the pathways and kinetics of the involved chemical reactions as well as on the gas-particle partitioning of the reaction products.

scholarly journals In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

2015 ◽  
Vol 15 (21) ◽  
pp. 30409-30471 ◽  
Author(s):  
B. B. Palm ◽  
P. Campuzano-Jost ◽  
A. M. Ortega ◽  
D. A. Day ◽  
L. Kaser ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Ambient Air ◽  
Organic Aerosol ◽  
Pine Forest ◽  
Oxidation Products ◽  
Oh Radicals ◽  
Aerosol Formation ◽  
Photochemical Aging

Abstract. Ambient air was oxidized by OH radicals in an oxidation flow reactor (OFR) located in a montane pine forest during the BEACHON-RoMBAS campaign to study biogenic secondary organic aerosol (SOA) formation and aging. High OH concentrations and short residence times allowed for semi-continuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative time scales of condensation of low volatility organic compounds (LVOCs) onto particles, condensational loss to the walls, and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 4 μg m-3 when LVOC fate corrected) compared to daytime (average 1 μg m-3 when LVOC fate corrected), with maximum formation observed at 0.4–1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene + p-cymene concentrations, including a substantial increase just after sunrise at 07:00 LT. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of small oxidized organic compounds, and net production at lower ages followed by net consumption of terpenoid oxidation products as photochemical age increased. New particle formation was observed in the reactor after oxidation, especially during times when precursor gas concentrations and SOA formation were largest. Approximately 6 times more SOA was formed in the reactor from OH oxidation than could be explained by the VOCs measured in ambient air. Several recently-developed instruments quantified ambient semi- and intermediate-volatility organic compounds (S/IVOCs) that were not detected by a PTR-TOF-MS. An SOA yield of 24–80 % from those compounds can explain the observed SOA, suggesting that these typically unmeasured S/IVOCs play a substantial role in ambient SOA formation. Our results allow ruling out condensation sticking coefficients much lower than 1. Our measurements help clarify the magnitude of SOA formation in forested environments, and demonstrate methods for interpretation of ambient OFR measurements.

scholarly journals Simulating regional scale secondary organic aerosol formation during the TORCH 2003 campaign in the southern UK

2006 ◽  
Vol 6 (2) ◽  
pp. 403-418 ◽  
Author(s):  
D. Johnson ◽  
S. R. Utembe ◽  
M. E. Jenkin ◽  
R. G. Derwent ◽  
G. D. Hayman ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Regional Scale ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Background Concentration ◽  
Aerosol Formation ◽  
Organic Species ◽  
Voc Oxidation ◽  
Partitioning Coefficients

Abstract. A photochemical trajectory model has been used to simulate the chemical evolution of air masses arriving at the TORCH field campaign site in the southern UK during late July and August 2003, a period which included a widespread and prolonged photochemical pollution episode. The model incorporates speciated emissions of 124 non-methane anthropogenic VOC and three representative biogenic VOC, coupled with a comprehensive description of the chemistry of their degradation. A representation of the gas/aerosol absorptive partitioning of ca. 2000 oxygenated organic species generated in the Master Chemical Mechanism (MCM v3.1) has been implemented, allowing simulation of the contribution to organic aerosol (OA) made by semi- and non-volatile products of VOC oxidation; emissions of primary organic aerosol (POA) and elemental carbon (EC) are also represented. Simulations of total OA mass concentrations in nine case study events (optimised by comparison with observed hourly-mean mass loadings derived from aerosol mass spectrometry measurements) imply that the OA can be ascribed to three general sources: (i) POA emissions; (ii) a "ubiquitous" background concentration of 0.7 µg m-3; and (iii) gas-to-aerosol transfer of lower volatility products of VOC oxidation generated by the regional scale processing of emitted VOC, but with all partitioning coefficients increased by a species-independent factor of 500. The requirement to scale the partitioning coefficients, and the implied background concentration, are both indicative of the occurrence of chemical processes within the aerosol which allow the oxidised organic species to react by association and/or accretion reactions which generate even lower volatility products, leading to a persistent, non-volatile secondary organic aerosol (SOA). The contribution of secondary organic material to the simulated OA results in significant elevations in the simulated ratio of organic carbon (OC) to EC, compared with the ratio of 1.1 assigned to the emitted components. For the selected case study events, [OC]/[EC] is calculated to lie in the range 2.7-9.8, values which are comparable with the high end of the range reported in the literature.

scholarly journals Mapping gas-phase organic reactivity and concomitant secondary organic aerosol formation: chemometric dimension reduction techniques for the deconvolution of complex atmospheric data sets

2015 ◽  
Vol 15 (14) ◽  
pp. 8077-8100 ◽  
Author(s):  
K. P. Wyche ◽  
P. S. Monks ◽  
K. L. Smallbone ◽  
J. F. Hamilton ◽  
M. R. Alfarra ◽  
...  
Keyword(s):  
Phase Composition ◽  
Dimension Reduction ◽  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Ambient Air ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Particle Phase ◽  
Aerosol Formation ◽  
Holistic View

Abstract. Highly non-linear dynamical systems, such as those found in atmospheric chemistry, necessitate hierarchical approaches to both experiment and modelling in order to ultimately identify and achieve fundamental process-understanding in the full open system. Atmospheric simulation chambers comprise an intermediate in complexity, between a classical laboratory experiment and the full, ambient system. As such, they can generate large volumes of difficult-to-interpret data. Here we describe and implement a chemometric dimension reduction methodology for the deconvolution and interpretation of complex gas- and particle-phase composition spectra. The methodology comprises principal component analysis (PCA), hierarchical cluster analysis (HCA) and positive least-squares discriminant analysis (PLS-DA). These methods are, for the first time, applied to simultaneous gas- and particle-phase composition data obtained from a comprehensive series of environmental simulation chamber experiments focused on biogenic volatile organic compound (BVOC) photooxidation and associated secondary organic aerosol (SOA) formation. We primarily investigated the biogenic SOA precursors isoprene, α-pinene, limonene, myrcene, linalool and β-caryophyllene. The chemometric analysis is used to classify the oxidation systems and resultant SOA according to the controlling chemistry and the products formed. Results show that "model" biogenic oxidative systems can be successfully separated and classified according to their oxidation products. Furthermore, a holistic view of results obtained across both the gas- and particle-phases shows the different SOA formation chemistry, initiating in the gas-phase, proceeding to govern the differences between the various BVOC SOA compositions. The results obtained are used to describe the particle composition in the context of the oxidised gas-phase matrix. An extension of the technique, which incorporates into the statistical models data from anthropogenic (i.e. toluene) oxidation and "more realistic" plant mesocosm systems, demonstrates that such an ensemble of chemometric mapping has the potential to be used for the classification of more complex spectra of unknown origin. More specifically, the addition of mesocosm data from fig and birch tree experiments shows that isoprene and monoterpene emitting sources, respectively, can be mapped onto the statistical model structure and their positional vectors can provide insight into their biological sources and controlling oxidative chemistry. The potential to extend the methodology to the analysis of ambient air is discussed using results obtained from a zero-dimensional box model incorporating mechanistic data obtained from the Master Chemical Mechanism (MCMv3.2). Such an extension to analysing ambient air would prove a powerful asset in assisting with the identification of SOA sources and the elucidation of the underlying chemical mechanisms involved.

scholarly journals Simulating regional scale secondary organic aerosol formation during the TORCH 2003 campaign in the southern UK

2005 ◽  
Vol 5 (4) ◽  
pp. 7829-7874 ◽  
Author(s):  
D. Johnson ◽  
S. R. Utembe ◽  
M. E. Jenkin ◽  
R. G. Derwent ◽  
G. D. Hayman ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Regional Scale ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Background Concentration ◽  
Aerosol Formation ◽  
Organic Species ◽  
Voc Oxidation ◽  
Partitioning Coefficients

Abstract. A photochemical trajectory model has been used to simulate the chemical evolution of air masses arriving at the TORCH field campaign site in the southern UK during late July and August 2003, a period which included a widespread and prolonged photochemical pollution episode. The model incorporates speciated emissions of 124 non-methane anthropogenic VOC and three representative biogenic VOC, coupled with a comprehensive description of the chemistry of their degradation. A representation of the gas/aerosol absorptive partitioning of ca. 2000 oxygenated organic species generated in the Master Chemical Mechanism (MCM v3.1) has been developed and implemented, allowing simulation of the contribution to organic aerosol (OA) made by semi- and non-volatile products of VOC oxidation; emissions of primary organic aerosol (POA) and elemental carbon (EC) are also represented. Simulations of total OA mass concentrations in nine case study events (optimised by comparison with observed mass loadings derived from aerosol mass spectrometry measurements) imply that the OA can be ascribed to three general sources: (i) POA emissions; (ii) a ubiquitous background concentration of 0.7 µg m−3; and (iii) gas-to-aerosol transfer of lower volatility products of VOC oxidation generated by the regional scale processing of emitted VOC, but with all partitioning coefficients increased by a species-independent factor of 500. The requirement to scale the partitioning coefficients, and the implied background concentration, are both indicative of the occurrence of chemical processes within the aerosol which allow the oxidised organic species to react by association and/or accretion reactions which generate even lower volatility products, leading to a persistent, non-volatile secondary organic aerosol (SOA). The contribution of secondary organic material to the simulated OA results in significant elevations in the simulated ratio of organic carbon (OC) to EC, compared with the ratio of 1.1 assigned to the emitted components. For the selected case study events, [OC]/[EC] is calculated to lie in the range 2.7–9.8, values which are comparable with the high end of the range reported in the literature.

scholarly journals Secondary organic aerosol formation from OH-initiated oxidation of <i>m</i>-xylene: effects of relative humidity on yield and chemical composition

2019 ◽  
Author(s):  
Qun Zhang ◽  
Yongfu Xu ◽  
Long Jia
Keyword(s):  
Relative Humidity ◽  
Mass Spectrometer ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Oh Radicals ◽  
Aerosol Formation ◽  
Scanning Mobility Particle Sizer ◽  
Significant Discrepancy ◽  
Liquid Chromatograph

Abstract. The effect of relative humidity (RH) on the secondary organic aerosol (SOA) formation from the photooxidation of m-xylene initiated by OH radicals in the absence of seed particles was investigated in a smog chamber. The SOA yields were determined based on the particle mass concentrations measured with a scanning mobility particle sizer (SMPS) and reacted m-xylene concentrations measured with a gas chromatograph-mass spectrometer (GC-MS). The SOA components were analyzed using Fourier transform infrared spectrometer (FTIR) and ultrahigh performance liquid chromatograph-electrospray ionization-high-resolution mass spectrometer (UPLC-ESI-HRMS). A significant discrepancy was observed in SOA mass concentration and yield variation with the RH conditions. The SOA yield is 13.8 % and 0.8 % at low RH (13.7 %) and high RH (79.1 %), respectively, with the difference being over an order of magnitude. The relative increase of C-O-C at high RH from the FTIR analysis of functional groups indicates that the oligomers from carbonyl compounds cannot well explain the suppression of SOA yield. Highly oxygenated molecules (HOMs) were observed to be suppressed in the HRMS spectra. The chemical mechanism for explaining the RH effects on SOA formation from m-xylene-OH system is proposed based on the analysis of both FTIR and HRMS measurements as well as Master Chemical Mechanism (MCM) simulations. The reduced SOA at high RH is mainly ascribed to the less formation of oligomers and the suppression of RO2 autoxidation. As a result, high RH can obstruct the oligomerization and autoxidation that contribute to the SOA formation.

scholarly journals Rate constant and secondary organic aerosol formation from the gas-phase reaction of eugenol with hydroxyl radicals

2019 ◽  
Vol 19 (3) ◽  
pp. 2001-2013 ◽  
Author(s):  
Changgeng Liu ◽  
Yongchun Liu ◽  
Tianzeng Chen ◽  
Jun Liu ◽  
Hong He
Keyword(s):  
Rate Constant ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Relative Rate ◽  
Organic Aerosol ◽  
Organic Nitrates ◽  
Phase Reaction ◽  
Aerosol Formation ◽  
Product Model ◽  
Formation Potential

Abstract. Methoxyphenols are an important organic component of wood-burning emissions and considered to be potential precursors of secondary organic aerosol (SOA). In this work, the rate constant and SOA formation potential for the OH-initiated reaction of 4-allyl-2-methoxyphenol (eugenol) were investigated for the first time in an oxidation flow reactor (OFR). The rate constant was 8.01±0.40×10-11 cm3 molecule−1 s−1, determined by the relative rate method. The SOA yield first increased and then decreased as a function of OH exposure and was also dependent on eugenol concentration. The maximum SOA yields (0.11–0.31) obtained at different eugenol concentrations could be expressed well by a one-product model. The carbon oxidation state (OSC) increased linearly and significantly as OH exposure rose, indicating that a high oxidation degree was achieved for SOA. In addition, the presence of SO2 (0–198 ppbv) and NO2 (0–109 ppbv) was conducive to increasing SOA yield, for which the maximum enhancement values were 38.6 % and 19.2 %, respectively. The N∕C ratio (0.032–0.043) indicated that NO2 participated in the OH-initiated reaction, subsequently forming organic nitrates. The results could be helpful for further understanding the SOA formation potential from the atmospheric oxidation of methoxyphenols and the atmospheric aging process of smoke plumes from biomass burning emissions.

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