Volatile organic compounds and isoprene oxidation products at a temperate deciduous forest site

Abstract. We present an evaluation of sources, sinks and turbulent transport of nitrogen oxides, ozone and volatile organic compounds (VOC) in the boundary layer over French Guyana and Suriname during the October 2005 GABRIEL campaign by simulating observations with a single-column chemistry and climate model (SCM) along a zonal transect. Simulated concentrations of O3 and NO as well as NO2 photolysis rates over the forest agree well with observations when a small soil-biogenic NO emission flux was applied. This suggests that the photochemical conditions observed during GABRIEL reflect a pristine tropical low-NOx regime. The SCM uses a compensation point approach to simulate nocturnal deposition and daytime emissions of acetone and methanol and produces daytime boundary layer mixing ratios in reasonable agreement with observations. The area average isoprene emission flux, inferred from the observed isoprene mixing ratios and boundary layer height, is about half the flux simulated with commonly applied emission algorithms. The SCM nevertheless simulates too high isoprene mixing ratios, whereas hydroxyl concentrations are strongly underestimated compared to observations, which can at least partly explain the discrepancy. Furthermore, the model substantially overestimates the isoprene oxidation products methlyl vinyl ketone (MVK) and methacrolein (MACR) partly due to a simulated nocturnal increase due to isoprene oxidation. This increase is most prominent in the residual layer whereas in the nocturnal inversion layer we simulate a decrease in MVK and MACR mixing ratios, assuming efficient removal of MVK and MACR. Entrainment of residual layer air masses, which are enhanced in MVK and MACR and other isoprene oxidation products, into the growing boundary layer poses an additional sink for OH which is thus not available for isoprene oxidation. Based on these findings, we suggest pursuing measurements of the tropical residual layer chemistry with a focus on the nocturnal depletion of isoprene and its oxidation products.

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Surface and boundary layer exchanges of volatile organic compounds, nitrogen oxides and ozone during the GABRIEL Campaign

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-11909-2008 ◽

2008 ◽

Vol 8 (3) ◽

pp. 11909-11965 ◽

Cited By ~ 5

Author(s):

L. Ganzeveld ◽

G. Eerdekens ◽

G. Feig ◽

H. Fischer ◽

H. Harder ◽

...

Keyword(s):

Boundary Layer ◽

Volatile Organic Compounds ◽

Organic Compounds ◽

Residual Layer ◽

Oxidation Products ◽

Emission Flux ◽

Mixing Ratios ◽

Volatile Organic ◽

Isoprene Oxidation ◽

Isoprene Oxidation Products

Abstract. We present an evaluation of sources, sinks and turbulent transport of nitrogen oxides, ozone and volatile organic compounds (VOC) in the boundary layer over French Guyana and Suriname during the October 2005 GABRIEL campaign by simulating observations with a single-column chemistry and climate model (SCM) along a zonal transect. Simulated concentrations of O3 and NO as well as NO2 photolysis rates over the forest agree well with observations when a small soil-biogenic NO emission flux was applied. This suggests that the photochemical conditions observed during GABRIEL reflect a pristine tropical low-NOx regime. The SCM uses a compensation point approach to simulate nocturnal deposition and daytime emissions of acetone and methanol and produces daytime boundary layer mixing ratios in reasonable agreement with observations. The area average isoprene emission flux, inferred from the observed isoprene mixing ratios and boundary layer height, is about half the flux simulated with commonly applied emission algorithms. The SCM nevertheless simulates too high isoprene mixing ratios, whereas hydroxyl concentrations are strongly underestimated compared to observations, which can at least partly explain the discrepancy. Furthermore, the model substantially overestimates the isoprene oxidation products methlyl vinyl ketone (MVK) and methacrolein (MACR) partly due to a simulated nocturnal increase due to isoprene oxidation. This increase is most prominent in the residual layer whereas in the nocturnal inversion layer we simulate a decrease in MVK and MACR mixing ratios, assuming efficient removal of MVK and MACR. Entrainment of residual layer air masses, which are enhanced in MVK and MACR and other isoprene oxidation products, into the growing boundary layer poses an additional sink for OH which is thus not available for isoprene oxidation. Based on these findings, we suggest pursuing measurements of the tropical residual layer chemistry with a focus on the nocturnal depletion of isoprene and its oxidation products.

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OH reactivity and concentrations of Biogenic Volatile Organic Compounds in a Mediterranean forest of downy oak trees

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-22047-2015 ◽

2015 ◽

Vol 15 (16) ◽

pp. 22047-22095 ◽

Cited By ~ 1

Author(s):

N. Zannoni ◽

V. Gros ◽

M. Lanza ◽

R. Sarda ◽

B. Bonsang ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Degradation Products ◽

Ambient Air ◽

Oxidation Products ◽

Deciduous Tree ◽

Forest Site ◽

Mediterranean Forests ◽

Oak Trees ◽

Volatile Organic

Abstract. Understanding the processes between the biosphere and the atmosphere is challenged by the difficulty to determine with enough accuracy the composition of the atmosphere. Total OH reactivity, which is defined as the total loss of the hydroxyl radical in the atmosphere, has proved to be an excellent tool to identify indirectly the important reactive species in ambient air. High levels of unknown reactivity were found in several forests worldwide and were often higher than at urban sites. Such results demonstrated the importance of OH reactivity for characterizing two of the major unknowns currently present associated to forests: the set of primary emissions from the canopy to the atmosphere and biogenic compounds oxidation pathways. Previous studies also highlighted the need to quantify OH reactivity and missing OH reactivity at more forested sites. Our study presents results of a field experiment conducted during late spring 2014 at the forest site at the Observatoire de Haute Provence, OHP, France. The forest is mainly composed of downy oak trees, a deciduous tree species characteristic of the Mediterranean region. We deployed the Comparative Reactivity Method and a set of state-of-the-art techniques such as Proton Transfer Reaction-Mass Spectrometry and Gas Chromatography to measure the total OH reactivity, the concentration of volatile organic compounds and main atmospheric constituents at the site. We sampled the air masses at two heights: 2 m, i.e. inside the canopy, and 10 m, i.e. above the canopy, where the mean canopy height is 5 m. We found that the OH reactivity at the site mainly depended on the main primary biogenic species emitted by the forest, which was isoprene and to a lesser extent by its degradation products and long lived atmospheric compounds (up to 26 % during daytime). We determined that the daytime total measured reactivity equaled the calculated reactivity obtained from the concentrations of the compounds measured at the site. Hence, no significant missing reactivity is reported in this specific site, neither inside, nor above the canopy. However, during two nights we reported a missing fraction of OH reactivity up to 50 %, possibly due to unmeasured oxidation products. Our results confirm the weak intra canopy oxidation, already suggested in a previous study focused on isoprene fluxes. They also demonstrate how helpful can be the OH reactivity as a tool to clearly characterize the suite of species present in the atmosphere. We show that our result of reactivity is among the highest reported in forests worldwide and stress the importance to quantify OH reactivity at more and diverse Mediterranean forests.

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Polar organic compounds in rural PM<sub>2.5</sub> aerosols from K-puszta, Hungary, during a 2003 summer field campaign: sources and diurnal variations

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-5-1863-2005 ◽

2005 ◽

Vol 5 (2) ◽

pp. 1863-1889 ◽

Cited By ~ 5

Author(s):

A. C. Ion ◽

R. Vermeylen ◽

I. Kourtchev ◽

J. Cafmeyer ◽

X. Chi ◽

...

Keyword(s):

Organic Compounds ◽

Malic Acid ◽

Photochemical Reactions ◽

Oxidation Products ◽

Forest Site ◽

Diurnal Pattern ◽

Field Campaign ◽

Photo Oxidation ◽

Isoprene Oxidation ◽

Isoprene Oxidation Products

Abstract. In the present study, we examined PM2.5 continental rural background aerosols, which were collected during a summer field campaign at K-puszta, Hungary (4 June–10 July 2003), a mixed coniferous/deciduous forest site characterized by intense solar radiation during summer. Emphasis was placed on polar oxygenated organic compounds that provide information on aerosol sources and source processes. Analysis was performed using gas chromatography/mass spectrometry (GC/MS) after suitable sample workup consisting of extraction with methanol and derivatisation into trimethylsilyl (TMS) derivatives. The major components detected at significant atmospheric concentrations were: (a) photo-oxidation products of isoprene including the 2-methyltetrols (2-methylthreitol and 2-methylerythritol) and 2-methylglyceric acid, (b) levoglucosan, a marker for biomass burning, (c) malic acid, an end-oxidation product of unsaturated fatty acids, and (d) the sugar alcohols, arabitol and mannitol, markers for fungal spores. Diurnal patterns with highest concentrations during day-time were observed for the isoprene oxidation products, i.e., the 2-methyltetrols and 2-methylglyceric acid, which can be regarded as supporting evidence for their fast photochemical formation from their locally emitted precursor. In addition, a diurnal pattern with highest concentrations during day-time was observed for the fungal markers, arabitol and mannitol, suggesting that the release of fungal fragments that are associated with the PM2.5 aerosol is enhanced during that time. Furthermore, a diurnal pattern was also found for levoglucosan with the highest concentrations at night when wood burning may take place in the settlements around the sampling site. In contrast, malic acid did not show day/night differences but was found to follow quite closely the particulate and organic carbon mass. This is interpreted as an indication that malic acid is formed in photochemical reactions which have a much longer overall time-scale than that of isoprene photo-oxidation, and the sources of its precursors are manifold, including both anthropogenic and natural emissions. On the basis of the high concentrations found for the isoprene oxidation products, i.e., the 2-methyltetrols (28.5 ng m-3) and 2-methylglyceric acid (7.6 ng m-3), it can be concluded that rapid photo-oxidation of isoprene is an important atmospheric chemistry process that contributes to secondary organic aerosol (SOA) formation at K-puszta during summer.

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Long-term measurements of volatile organic compounds highlight the importance of sesquiterpenes for the atmospheric chemistry of a boreal forest

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-13839-2018 ◽

2018 ◽

Vol 18 (19) ◽

pp. 13839-13863 ◽

Cited By ~ 24

Author(s):

Heidi Hellén ◽

Arnaud P. Praplan ◽

Toni Tykkä ◽

Ilona Ylivinkka ◽

Ville Vakkari ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Boreal Forest ◽

Organic Compounds ◽

Atmospheric Chemistry ◽

Vertical Mixing ◽

Diurnal Variations ◽

Oxidation Products ◽

Forest Site ◽

Seasonal And Diurnal Variations ◽

Volatile Organic

Abstract. The concentrations of terpenoids (isoprene; monoterpenes, MTs; and sesquiterpenes, SQTs) and oxygenated volatile organic compounds (OVOCs; i.e. aldehydes, alcohols, acetates and volatile organic acids, VOAs) were investigated during 2 years at a boreal forest site in Hyytiälä, Finland, using in situ gas chromatograph mass spectrometers (GC-MSs). Seasonal and diurnal variations of terpenoid and OVOC concentrations as well as their relationship with meteorological factors were studied. Of the VOCs examined, C2–C7 unbranched VOAs showed the highest concentrations, mainly due to their low reactivity. Of the terpenoids, MTs showed the highest concentrations at the site, but seven different highly reactive SQTs were also detected. The monthly and daily mean concentrations of most terpenoids, aldehydes and VOAs were highly dependent on the temperature. The highest exponential correlation with temperature was found for a SQT (β-caryophyllene) in summer. The diurnal variations in the concentrations could be explained by sources, sinks and vertical mixing. The diurnal variations in MT concentrations were strongly affected by vertical mixing. Based on the temperature correlations and mixing layer height (MLH), simple proxies were developed for estimating the MT and SQT concentrations. To estimate the importance of different compound groups and compounds in local atmospheric chemistry, reactivity with main oxidants (hydroxyl radical, OH; nitrate radical, NO3; and ozone, O3) and production rates of oxidation products (OxPRs) were calculated. The MTs dominated OH and NO3 radical chemistry, but the SQTs greatly impacted O3 chemistry, even though the concentrations of SQT were 30 times lower than the MT concentrations. SQTs were also the most important for the production of oxidation products. Since the SQTs show high secondary organic aerosol (SOA) yields, the results clearly indicate the importance of SQTs for local SOA production.

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Measurements of volatile organic compounds over West Africa

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-3861-2010 ◽

2010 ◽

Vol 10 (2) ◽

pp. 3861-3892 ◽

Cited By ~ 8

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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Contributions to OH reactivity from unexplored volatile organic compounds measured by PTR-ToF-MS – A case study in a suburban forest of the Seoul Metropolitan Area during KORUS-AQ 2016

10.5194/acp-2020-174 ◽

2020 ◽

Cited By ~ 1

Author(s):

Dianne Sanchez ◽

Roger Seco ◽

Dasa Gu ◽

Alex Guenther ◽

John Mak ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Mass Spectrometer ◽

Metropolitan Area ◽

Forest Canopy ◽

Oxidation Products ◽

Ionization Mass ◽

Seoul Metropolitan Area ◽

Volatile Organic ◽

Tof Ms

Abstract. We report OH reactivity observations by a chemical ionization mass spectrometer – comparative reactivity method (CIMS-CRM) instrument in a suburban forest of the Seoul Metropolitan Area (SMA) during Korea US Air Quality Study (KORUS-AQ 2016) from mid-May to mid-June of 2016. A comprehensive observational suite was deployed to quantify reactive trace gases inside of the forest canopy including a high-resolution proton transfer reaction time of flight mass spectrometer (PTR-ToF-MS). An average OH reactivity of 30.7 ± 5.1 s−1 was observed, while the OH reactivity calculated from CO, NO + NO2 (NOx), ozone (O3), sulfur dioxide (SO2), and 14 volatile organic compounds (VOCs) was 11.8 ± 1.0 s−1. An analysis of 346 peaks from the PTR-ToF-MS accounted for an additional 6.0 ± 2.2 s−1 of the total measured OH reactivity, leaving 42.0 % missing OH reactivity. The missing OH reactivity most likely comes from VOC oxidation products of both biogenic and anthropogenic origin.

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Turbulent exchange and segregation of HO<sub>x</sub> radicals and volatile organic compounds above a deciduous forest

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-6215-2010 ◽

2010 ◽

Vol 10 (13) ◽

pp. 6215-6235 ◽

Cited By ~ 35

Author(s):

R. Dlugi ◽

M. Berger ◽

M. Zelger ◽

A. Hofzumahaus ◽

M. Siese ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Forest Canopy ◽

Deciduous Forest ◽

Inorganic Compounds ◽

Sonic Anemometer ◽

Transport Processes ◽

Biogenic Volatile Organic Compounds ◽

Measuring Point ◽

Volatile Organic

Abstract. The eddy covariance method was applied for the first time to estimate fluxes of OH and HO2 together with fluxes of isoprene, the sum of methyl vinyl ketone (MVK) and methacrolein (MACR) and the sum of monoterpenes above a mixed deciduous forest. Highly sensitive measurements of OH and HO2 were performed by laser induced fluorescence (LIF), and biogenic volatile organic compounds (BVOCs) were measured by Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) at a time resolution of 5 s, each. Wind speed was measured by a sonic anemometer at 10 Hz. The one-day feasibility study was conducted at a total height of 37 m, about 7 m above forest canopy, during the ECHO (Emission and CHemical transformation of biogenic volatile Organic compounds) intensive field study in July 2003. The daytime measurements yielded statistically significant OH fluxes directed downward into the direction of the canopy and HO2 fluxes mainly upward out of the canopy. This hints towards a significant local chemical sink of OH by reactions with BVOCs, other organic and inorganic compounds and conversion of OH to HO2 above the canopy. For OH the measured flux is locally balanced by chemical sources and sinks and direct transport of OH plays no important role for the local chemical OH budget at the measurement height, as expected from the short OH lifetime (<1 s). For HO2 the chemical lifetime (20 s) is in the range of the turbulent transport time for transfer between the top of the canopy and the measuring point. In this case, the radical balance is significantly influenced by both chemistry and transport processes. In addition, the highly time-resolved trace gas measurements were used to calculate the intensity of segregation of OH and BVOCs, demonstrating that the effective reaction rate of isoprene and OH was slowed down as much as 15% due to inhomogeneous mixing of the reactants. The paper describes the results, the applied methods and provides a detailed analysis of possible systematic errors of the covariance products.

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Experimental determination of the partitioning coefficient of β-pinene oxidation products in SOAs

Physical Chemistry Chemical Physics ◽

10.1039/c5cp01608h ◽

2015 ◽

Vol 17 (22) ◽

pp. 14796-14804 ◽

Cited By ~ 10

Author(s):

Thorsten Hohaus ◽

Iulia Gensch ◽

Joel Kimmel ◽

Douglas R. Worsnop ◽

Astrid Kiendler-Scharr

Keyword(s):

Volatile Organic Compounds ◽

Experimental Determination ◽

Organic Compounds ◽

Oxidation Products ◽

Particle Phase ◽

Partitioning Coefficient ◽

Volatile Organic ◽

Measured Particle

Measured particle phase concentrations of semi-volatile organic compounds exceed those predicted by absorption equilibrium gas-particle partitioning by orders of magnitude.

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Direct ecosystem fluxes of volatile organic compounds from oil palms in South-East Asia

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-8995-2011 ◽

2011 ◽

Vol 11 (17) ◽

pp. 8995-9017 ◽

Cited By ~ 63

Author(s):

P. K. Misztal ◽

E. Nemitz ◽

B. Langford ◽

C. F. Di Marco ◽

G. J. Phillips ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Canopy Temperature ◽

Proton Transfer Reaction ◽

Oxidation Products ◽

Palm Trees ◽

Volatile Organic ◽

Resistance Approach ◽

Oil Palms ◽

Malaysian Borneo

Abstract. This paper reports the first direct eddy covariance fluxes of reactive biogenic volatile organic compounds (BVOCs) from oil palms to the atmosphere using proton-transfer-reaction mass spectrometry (PTR-MS), measured at a plantation in Malaysian Borneo. At midday, net isoprene flux constituted the largest fraction (84 %) of all emitted BVOCs measured, at up to 30 mg m−2 h−1 over 12 days. By contrast, the sum of its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) exhibited clear deposition of 1 mg m−2 h−1, with a small average canopy resistance of 230 s m−1. Approximately 15 % of the resolved BVOC flux from oil palm trees could be attributed to floral emissions, which are thought to be the largest reported biogenic source of estragole and possibly also toluene. Although on average the midday volume mixing ratio of estragole exceeded that of toluene by almost a factor of two, the corresponding fluxes of these two compounds were nearly the same, amounting to 0.81 and 0.76 mg m−2 h−1, respectively. By fitting the canopy temperature and PAR response of the MEGAN emissions algorithm for isoprene and other emitted BVOCs a basal emission rate of isoprene of 7.8 mg m−2 h−1 was derived. We parameterise fluxes of depositing compounds using a resistance approach using direct canopy measurements of deposition. Consistent with Karl et al. (2010), we also propose that it is important to include deposition in flux models, especially for secondary oxidation products, in order to improve flux predictions.

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