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

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-5-1805-2005 ◽

2005 ◽

Vol 5 (7) ◽

pp. 1805-1814 ◽

Cited By ~ 117

Author(s):

A. C. Ion ◽

R. Vermeylen ◽

I. Kourtchev ◽

J. Cafmeyer ◽

X. Chi ◽

...

Keyword(s):

Organic Compounds ◽

Malic Acid ◽

Sampling Site ◽

Photochemical Reactions ◽

Oxidation Products ◽

Forest Site ◽

Supporting Evidence ◽

Diel Pattern ◽

Field Campaign ◽

Photo Oxidation

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. 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 intermediate in the oxidation of unsaturated fatty acids, and (d) the sugar alcohols, arabitol and mannitol, markers for fungal spores. Diel patterns with highest concentrations during day-time were observed for the 2-methyltetrols, which can be regarded as supporting evidence for their fast photochemical formation from locally emitted isoprene. In addition, a diel pattern with highest concentrations during day-time was observed for the fungal markers, suggesting that the release of fungal fragments that are associated with the PM2.5 aerosol is enhanced during that time. Furthermore, a diel 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 during day-time, 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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Volatile organic compounds and isoprene oxidation products at a temperate deciduous forest site

Journal of Geophysical Research Atmospheres ◽

10.1029/98jd00969 ◽

1998 ◽

Vol 103 (D17) ◽

pp. 22397-22414 ◽

Cited By ~ 55

Author(s):

Detlev Helmig ◽

Jim Greenberg ◽

Alex Guenther ◽

Pat Zimmerman ◽

Chris Geron

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Deciduous Forest ◽

Oxidation Products ◽

Forest Site ◽

Temperate Deciduous Forest ◽

Volatile Organic ◽

Temperate Deciduous ◽

Isoprene Oxidation ◽

Isoprene 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 ◽

10.5194/acp-8-6223-2008 ◽

2008 ◽

Vol 8 (20) ◽

pp. 6223-6243 ◽

Cited By ~ 60

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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Secondary organic aerosol from chlorine-initiated oxidation of isoprene

10.5194/acp-2017-342 ◽

2017 ◽

Author(s):

Dongyu S. Wang ◽

Lea Hildebrandt Ruiz

Keyword(s):

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Oxidative Capacity ◽

Oxidation Products ◽

Ionization Mass ◽

Photo Oxidation ◽

Wide Range ◽

Chlorine Radicals ◽

Isoprene Oxidation ◽

Isoprene Oxidation Products

Abstract. Recent studies have found inland concentrations of reactive chlorine species to be higher than expected, suggesting that atmospheric chlorine chemistry is more extensive than previously thought. Chlorine radicals can interact with HOx radicals and nitrogen oxides (NOx) to alter the oxidative capacity of the atmosphere. They are known to rapidly oxidize a wide range of volatile organic compounds (VOC) found in the atmosphere, yet little is known about secondary organic aerosol (SOA) formation from chlorine-initiated photo-oxidation and its atmospheric implications. Environmental chamber experiments were carried out under low-NOx conditions with isoprene and chlorine as primary VOC and oxidant sources. Upon complete isoprene consumption, observed SOA yields ranged from 8 % to 36 %, decreasing with extended photo-oxidation and SOA aging. A High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer was used to determine the molecular composition of gas-phase species using iodide-water and hydronium-water ionization. Ions consistent with isoprene-derived epoxydiol (IEPOX) and other common OH-isoprene oxidation products were observed, evident of secondary OH production and resulting chemistry from Cl-initiated reactions.

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