scholarly journals Explicit modelling of SOA formation from α-pinene photooxidation: sensitivity to vapour pressure estimation

2011 ◽  
Vol 11 (3) ◽  
pp. 10121-10158 ◽  
Author(s):  
R. Valorso ◽  
B. Aumont ◽  
M. Camredon ◽  
T. Raventos-Duran ◽  
C. Mouchel-Vallon ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Vapour Pressure ◽  
Estimation Method ◽  
Organic Aerosol ◽  
Reaction Scheme ◽  
Oxidation Products ◽  
Organic Species ◽  
Structure Activity ◽  
Volatile Organic ◽  
Kinetics Of

Abstract. The sensitivity of the formation of secondary organic aerosol (SOA) to the estimated vapour pressures of the condensable oxidation products is explored. A highly detailed reaction scheme was generated for α-pinene photooxidation using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A). Vapour pressures (Pvap) were estimated with three commonly used structure activity relationships. The values of Pvap were compared for the set of secondary species generated by GECKO-A to describe α-pinene oxidation. Discrepancies in the predicted vapour pressures were found to increase with the number of functional groups borne by the species. For semi-volatile organic compounds (i.e. organic species of interest for SOA formation), differences in the predicted Pvap range between a factor of 5 to 200 in average. The simulated SOA concentrations were compared to SOA observations in the Caltech chamber during three experiments performed under a range of NOx conditions. While the model captures the qualitative features of SOA formation for the chamber experiments, SOA concentrations are systematically overestimated. For the conditions simulated, the modelled SOA speciation appears to be rather insensitive to the Pvap estimation method.

scholarly journals Explicit modelling of SOA formation from α-pinene photooxidation: sensitivity to vapour pressure estimation

2011 ◽  
Vol 11 (14) ◽  
pp. 6895-6910 ◽  
Author(s):  
R. Valorso ◽  
B. Aumont ◽  
M. Camredon ◽  
T. Raventos-Duran ◽  
C. Mouchel-Vallon ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Vapour Pressure ◽  
Estimation Method ◽  
Organic Aerosol ◽  
Reaction Scheme ◽  
Oxidation Products ◽  
Organic Species ◽  
Structure Activity ◽  
Volatile Organic ◽  
Kinetics Of

Abstract. The sensitivity of the formation of secondary organic aerosol (SOA) to the estimated vapour pressures of the condensable oxidation products is explored. A highly detailed reaction scheme was generated for α-pinene photooxidation using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A). Vapour pressures (Pvap) were estimated with three commonly used structure activity relationships. The values of Pvap were compared for the set of secondary species generated by GECKO-A to describe α-pinene oxidation. Discrepancies in the predicted vapour pressures were found to increase with the number of functional groups borne by the species. For semi-volatile organic compounds (i.e. organic species of interest for SOA formation), differences in the predicted Pvap range between a factor of 5 to 200 on average. The simulated SOA concentrations were compared to SOA observations in the Caltech chamber during three experiments performed under a range of NOx conditions. While the model captures the qualitative features of SOA formation for the chamber experiments, SOA concentrations are systematically overestimated. For the conditions simulated, the modelled SOA speciation appears to be rather insensitive to the Pvap estimation method.

scholarly journals Emissions of biogenic volatile organic compounds and subsequent photochemical production of secondary organic aerosol in mesocosm studies of temperate and tropical plant species

2014 ◽  
Vol 14 (23) ◽  
pp. 12781-12801 ◽  
Author(s):  
K. P. Wyche ◽  
A. C. Ryan ◽  
C. N. Hewitt ◽  
M. R. Alfarra ◽  
G. McFiggans ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Organic Aerosol ◽  
Reaction Chamber ◽  
Oxidation Products ◽  
Photo Oxidation ◽  
Tropical Plant ◽  
Aerosol Mass ◽  
Volatile Organic ◽  
Seed Aerosol

Abstract. Silver birch (Betula pendula) and three Southeast Asian tropical plant species (Ficus cyathistipula, Ficus benjamina and Caryota millis) from the pantropical fig and palm genera were grown in a purpose-built and environment-controlled whole-tree chamber. The volatile organic compounds emitted from these trees were characterised and fed into a linked photochemical reaction chamber where they underwent photo-oxidation under a range of controlled conditions (relative humidity or RH ~65–89%, volatile organic compound-to-NOx or VOC / NOx ~3–9 and NOx ~2 ppbV). Both the gas phase and the aerosol phase of the reaction chamber were monitored in detail using a comprehensive suite of on-line and off-line chemical and physical measurement techniques. Silver birch was found to be a high monoterpene and sesquiterpene but low isoprene emitter, and its emissions were observed to produce measurable amounts of secondary organic aerosol (SOA) via both nucleation and condensation onto pre-existing seed aerosol (YSOA 26–39%). In contrast, all three tropical species were found to be high isoprene emitters with trace emissions of monoterpenes and sesquiterpenes. In tropical plant experiments without seed aerosol there was no measurable SOA nucleation, but aerosol mass was shown to increase when seed aerosol was present. Although principally isoprene emitting, the aerosol mass produced from tropical fig was mostly consistent (i.e. in 78 out of 120 aerosol mass calculations using plausible parameter sets of various precursor specific yields) with condensation of photo-oxidation products of the minor volatile organic compounds (VOCs) co-emitted; no significant aerosol yield from condensation of isoprene oxidation products was required in the interpretations of the experimental results. This finding is in line with previous reports of organic aerosol loadings consistent with production from minor biogenic VOCs co-emitted with isoprene in principally isoprene-emitting landscapes in Southeast Asia. Moreover, in general the amount of aerosol mass produced from the emissions of the principally isoprene-emitting plants was less than would be expected from published single-VOC experiments, if co-emitted species were solely responsible for the final SOA mass. Interpretation of the results obtained from the fig data sets leaves room for a potential role for isoprene in inhibiting SOA formation under certain ambient atmospheric conditions, although instrumental and experimental constraints impose a level of caution in the interpretation of the results. Concomitant gas- and aerosol-phase composition measurements also provide a detailed overview of numerous key oxidation mechanisms at work within the systems studied, and their combined analysis provides insight into the nature of the SOA formed.

scholarly journals Characterising the evaporation kinetics of water and semi-volatile organic compounds from viscous multicomponent organic aerosol particles

2017 ◽  
Vol 19 (47) ◽  
pp. 31634-31646 ◽  
Author(s):  
Stephen Ingram ◽  
Chen Cai ◽  
Young-Chul Song ◽  
David R. Glowacki ◽  
David O. Topping ◽  
...  
Keyword(s):  
Particle Size ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Aerosol Particle ◽  
Aerosol Particles ◽  
Organic Aerosol ◽  
Volatile Organic ◽  
Aerosol Particle Size ◽  
Kinetics Of ◽  
Evaporation Kinetics

Here we present methods to simultaneously investigate diffusivities and volatilities in studies of evolving single aerosol particle size and composition.

scholarly journals Contributions of individual reactive biogenic volatile organic compounds to organic nitrates above a mixed forest

2012 ◽  
Vol 12 (21) ◽  
pp. 10125-10143 ◽  
Author(s):  
K. A. Pratt ◽  
L. H. Mielke ◽  
P. B. Shepson ◽  
A. M. Bryan ◽  
A. L. Steiner ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Mixed Forest ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Biogenic Volatile Organic Compounds ◽  
Nitrate Production ◽  
Volatile Organic

Abstract. Biogenic volatile organic compounds (BVOCs) can react in the atmosphere to form organic nitrates, which serve as NOx (NO + NO2) reservoirs, impacting ozone and secondary organic aerosol production, the oxidative capacity of the atmosphere, and nitrogen availability to ecosystems. To examine the contributions of biogenic emissions and the formation and fate of organic nitrates in a forest environment, we simulated the oxidation of 57 individual BVOCs emitted from a rural mixed forest in northern Michigan. Key BVOC-oxidant reactions were identified for future laboratory and field investigations into reaction rate constants, yields, and speciation of oxidation products. Of the total simulated organic nitrates, monoterpenes contributed ~70% in the early morning at ~12 m above the forest canopy when isoprene emissions were low. In the afternoon, when vertical mixing and isoprene nitrate production were highest, the simulated contribution of isoprene-derived organic nitrates was greater than 90% at all altitudes, with the concentration of secondary isoprene nitrates increasing with altitude. Notably, reaction of isoprene with NO3 leading to isoprene nitrate formation was found to be significant (~8% of primary organic nitrate production) during the daytime, and monoterpene reactions with NO3 were simulated to comprise up to ~83% of primary organic nitrate production at night. Lastly, forest succession, wherein aspen trees are being replaced by pine and maple trees, was predicted to lead to increased afternoon concentrations of monoterpene-derived organic nitrates. This further underscores the need to understand the formation and fate of these species, which have different chemical pathways and oxidation products compared to isoprene-derived organic nitrates and can lead to secondary organic aerosol formation.

scholarly journals Contributions of individual reactive biogenic volatile organic compounds to organic nitrates above a mixed forest

2012 ◽  
Vol 12 (7) ◽  
pp. 17031-17086 ◽  
Author(s):  
K. A. Pratt ◽  
L. H. Mielke ◽  
P. B. Shepson ◽  
A. M. Bryan ◽  
A. L. Steiner ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Secondary Organic Aerosol ◽  
Mixed Forest ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Organic Nitrates ◽  
Aerosol Formation ◽  
Biogenic Volatile Organic Compounds ◽  
Volatile Organic

Abstract. Biogenic volatile organic compounds (BVOCs) can react in the atmosphere to form organic nitrates, which serve as NOx (NO + NO2) reservoirs, impacting ozone and secondary organic aerosol production, the oxidative capacity of the atmosphere, and nitrogen availability to ecosystems. To examine the contributions of biogenic emissions and the formation and fate of organic nitrates in a forest environment, we simulated the oxidation of 57 individual BVOCs emitted from a rural mixed forest in Northern Michigan. Of the total simulated organic nitrates, monoterpenes contributed ~70% in the early morning at ~12 m above the forest canopy when isoprene emissions were low. In the afternoon, when vertical mixing and isoprene nitrate production were highest, the simulated contribution of isoprene-derived organic nitrates was greater than 90% at all altitudes, with the concentration of secondary isoprene nitrates increasing with altitude. Key BVOC-oxidant reactions were identified for future laboratory and field investigations into reaction rate constants, yields, and speciation of oxidation products. Forest succession, wherein aspen trees are being replaced by pine and maple trees, was predicted to lead to increased afternoon concentrations of monoterpene-derived organic nitrates. This further underscores the need to understand the formation and fate of these species, which have different chemical pathways and oxidation products compared to isoprene-derived organic nitrates and can lead to secondary organic aerosol formation.

scholarly journals Aging of atmospheric aerosols and the role of iron in catalyzing brown carbon formation

2021 ◽  
Author(s):  
Hind A. A. Al-Abadleh
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Atmospheric Aerosols ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Atmospheric Oxidation ◽  
Carbon Formation ◽  
Brown Carbon ◽  
Volatile Organic

Extensive research has been done on the processes that lead to the formation of secondary organic aerosol (SOA) including atmospheric oxidation of volatile organic compounds (VOCs) from biogenic and anthropogenic...

Two distinct mechanisms upon absorption of volatile organic compounds into siloxane polymers

Soft Matter ◽  
2018 ◽  
Vol 14 (12) ◽  
pp. 2206-2218 ◽  
Author(s):  
John E. Saunders ◽  
Hao Chen ◽  
Chris Brauer ◽  
McGregor Clayton ◽  
Hans-Peter Loock
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Desorption Kinetics ◽  
Volatile Organic ◽  
Siloxane Polymers ◽  
Kinetics Of

From measurements of the absorption and desorption kinetics of VOCs into polysiloxane materials evidence is found for two competing processes.

scholarly journals Characterization of secondary organic aerosol from heated-cooking-oil emissions: evolution in composition and volatility

2021 ◽  
Vol 21 (6) ◽  
pp. 5137-5149 ◽  
Author(s):  
Manpreet Takhar ◽  
Yunchun Li ◽  
Arthur W. H. Chan
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Secondary Organic Aerosol ◽  
Carbon Number ◽  
Complex Mixture ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Atmospheric Evolution ◽  
Oxidative Aging ◽  
Cooking Oil

Abstract. Cooking emissions account for a major fraction of urban organic aerosol. It is therefore important to understand the atmospheric evolution in the physical and chemical properties of organic compounds emitted from cooking activities. In this work, we investigate the formation of secondary organic aerosol (SOA) from oxidation of gas-phase organic compounds from heated cooking oil. The chemical composition of cooking SOA is analyzed using thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS). While the particle-phase composition of SOA is a highly complex mixture, we adopt a new method to achieve molecular speciation of the SOA. All the GC-elutable material is classified by the constituent functional groups, allowing us to provide a molecular description of its chemical evolution upon oxidative aging. Our results demonstrate an increase in average oxidation state (from −0.6 to −0.24) and decrease in average carbon number (from 5.2 to 4.9) with increasing photochemical aging of cooking oil, suggesting that fragmentation reactions are key processes in the oxidative aging of cooking emissions within 2 d equivalent of ambient oxidant exposure. Moreover, we estimate that aldehyde precursors from cooking emissions account for a majority of the SOA formation and oxidation products. Overall, our results provide insights into the atmospheric evolution of cooking SOA, a majority of which is derived from gas-phase oxidation of aldehydes.

scholarly journals Measurements of volatile organic compounds over West Africa

2010 ◽  
Vol 10 (2) ◽  
pp. 3861-3892 ◽  
Author(s):  
J. G. Murphy ◽  
D. E. Oram ◽  
C. E. Reeves
Keyword(s):  
Boundary Layer ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Marine Boundary Layer ◽  
Deep Convection ◽  
Proton Transfer Reaction ◽  
Oxidation Products ◽  
High Time Resolution ◽  
Airborne Measurements ◽  
Volatile Organic

Abstract. In this paper we describe measurements of volatile organic compounds (VOCs) made using a Proton Transfer Reaction Mass Spectrometer (PTR-MS) aboard the UK Facility for Atmospheric Airborne Measurements during the African Monsoon Multidisciplinary Analyses (AMMA) campaign. Observations were made during approximately 85 h of flying time between 17 July and 17 August 2006, above an area between 4° N and 18° N and 3° W and 4° E, encompassing ocean, mosaic forest, and the Sahel desert. High time resolution observations of counts at mass to charge (m/z) ratios of 42, 59, 69, 71, and 79 were used to calculate mixing ratios of acetonitrile, acetone, isoprene, the sum of methyl vinyl ketone and methacrolein, and benzene, respectively using laboratory-derived humidity-dependent calibration factors. Strong spatial associations between vegetation and isoprene and its oxidation products were observed in the boundary layer, consistent with biogenic emissions followed by rapid atmospheric oxidation. Acetonitrile, benzene, and acetone were all enhanced in airmasses which had been heavily influenced by biomass burning. Benzene and acetone were also elevated in airmasses with urban influence from cities such as Lagos, Cotonou, and Niamey. The observations provide evidence that both deep convection and mixing associated with fair-weather cumulus were responsible for vertical redistribution of VOCs emitted from the surface. Profiles over the ocean showed a depletion of acetone in the marine boundary layer, but no significant decrease for acetonitrile.

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