Observations of oxidation products above a forest imply biogenic emissions of very reactive compounds

Abstract. Vertical gradients of mixing ratios of volatile organic compounds have been measured in a Ponderosa pine forest in Central California (38.90° N, 120.63° W, 1315m). These measurements reveal large quantities of previously unreported oxidation products of short lived biogenic precursors. The emission of biogenic precursors must be in the range of 13-66µmol m-2h-1 to produce the observed oxidation products. That is 6-30 times the emissions of total monoterpenes observed above the forest canopy on a molar basis. These reactive precursors constitute a large fraction of biogenic emissions at this site, and are not included in current emission inventories. When oxidized by ozone they should efficiently produce secondary aerosol and hydroxyl radicals.

Download Full-text

Observations of oxidation products above a forest imply biogenic emissions of very reactive compounds

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-4-5345-2004 ◽

2004 ◽

Vol 4 (5) ◽

pp. 5345-5365 ◽

Cited By ~ 7

Author(s):

R. Holzinger ◽

A. Lee ◽

K. T. Paw U ◽

A. H. Goldstein

Keyword(s):

Organic Compounds ◽

Hydroxyl Radicals ◽

Forest Canopy ◽

Oxidation Products ◽

Biogenic Emissions ◽

Emission Inventories ◽

Central California ◽

Molar Basis ◽

Volatile Organic ◽

Current Emission

Abstract. Measurements of volatile organic compounds in a pine forest (Central California, 38.90° N, 120.63° W, 1315 m) reveal large quantities of previously unreported oxidation products of short lived biogenic precursors. The emission of biogenic precursors must be in the range of 13–66 µmol m−2 h−1 to produce the observed oxidation products. That is 6–30 times the emissions of total monoterpenes observed above the forest canopy on a molar basis. These reactive precursors constitute the largest fraction of biogenic emissions at this site, and are not included in current emission inventories. When oxidized by ozone they should efficiently produce secondary aerosol and hydroxyl radicals.

Download Full-text

Missing peroxy radical sources within a summertime ponderosa pine forest

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-4715-2014 ◽

2014 ◽

Vol 14 (9) ◽

pp. 4715-4732 ◽

Cited By ~ 31

Author(s):

G. M. Wolfe ◽

C. Cantrell ◽

S. Kim ◽

R. L. Mauldin III ◽

T. Karl ◽

...

Keyword(s):

Ponderosa Pine ◽

Forest Canopy ◽

Strong Dependence ◽

Rocky Mountain ◽

Peroxy Radical ◽

Pine Forest ◽

Chemical Mechanism ◽

Peroxy Radicals ◽

Mixing Ratios ◽

Ponderosa Pine Forest

Abstract. Organic peroxy (RO2) and hydroperoxy (HO2) radicals are key intermediates in the photochemical processes that generate ozone, secondary organic aerosol and reactive nitrogen reservoirs throughout the troposphere. In regions with ample biogenic hydrocarbons, the richness and complexity of peroxy radical chemistry presents a significant challenge to current-generation models, especially given the scarcity of measurements in such environments. We present peroxy radical observations acquired within a ponderosa pine forest during the summer 2010 Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen – Rocky Mountain Organic Carbon Study (BEACHON-ROCS). Total peroxy radical mixing ratios reach as high as 180 pptv (parts per trillion by volume) and are among the highest yet recorded. Using the comprehensive measurement suite to constrain a near-explicit 0-D box model, we investigate the sources, sinks and distribution of peroxy radicals below the forest canopy. The base chemical mechanism underestimates total peroxy radicals by as much as a factor of 3. Since primary reaction partners for peroxy radicals are either measured (NO) or underpredicted (HO2 and RO2, i.e., self-reaction), missing sources are the most likely explanation for this result. A close comparison of model output with observations reveals at least two distinct source signatures. The first missing source, characterized by a sharp midday maximum and a strong dependence on solar radiation, is consistent with photolytic production of HO2. The diel profile of the second missing source peaks in the afternoon and suggests a process that generates RO2 independently of sun-driven photochemistry, such as ozonolysis of reactive hydrocarbons. The maximum magnitudes of these missing sources (~120 and 50 pptv min−1, respectively) are consistent with previous observations alluding to unexpectedly intense oxidation within forests. We conclude that a similar mechanism may underlie many such observations.

Download Full-text

Methyl chavicol: characterization of its biogenic emission rate, abundance, and oxidation products in the atmosphere

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-19707-2008 ◽

2008 ◽

Vol 8 (6) ◽

pp. 19707-19741 ◽

Cited By ~ 2

Author(s):

N. C. Bouvier-Brown ◽

A. H. Goldstein ◽

D. R. Worton ◽

D. M. Matross ◽

J. B. Gilman ◽

...

Keyword(s):

Sierra Nevada ◽

Atmospheric Chemistry ◽

Ponderosa Pine ◽

Emission Rate ◽

Oxidation Products ◽

Biogenic Emission ◽

Methyl Chavicol ◽

Mixing Ratios ◽

Sierra Nevada Mountains ◽

Ponderosa Pine Forest

Abstract. We report measurements of ambient atmospheric mixing ratios for methyl chavicol and determine its biogenic emission rate. Methyl chavicol, a biogenic oxygenated aromatic compound, is abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol was detected simultaneously by three in-situ instruments – a gas chromatograph with mass spectrometer detector (GC-MS), a proton transfer reaction mass spectrometer (PTR-MS), and a thermal desorption aerosol GC-MS (TAG) – and found to be abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol atmospheric mixing ratios are strongly correlated with 2-methyl-3-buten-2-ol (MBO), a light- and temperature-dependent biogenic emission from the ponderosa pine trees at Blodgett Forest. Scaling from this correlation, methyl chavicol emissions account for 4–68% of the carbon mass emitted as MBO in the daytime, depending on the season. From this relationship, we estimate a daytime basal emission rate of 0.72–10.2 μgCg−1h−1, depending on needle age and seasonality. We also present the first observations of its oxidation products (4-methoxybenzaldehyde and 4-methyoxy benzene acetaldehyde) in the ambient atmosphere. Methyl chavicol is a major essential oil component of many plant species. This work suggests that methyl chavicol plays a significant role in the atmospheric chemistry of Blodgett Forest, and potentially other sites, and should be included explicitly in both biogenic volatile organic carbon emission and atmospheric chemistry models.

Download Full-text

Chamber Studies of NO3 reactivity during the oxidation of isoprene

10.5194/egusphere-egu2020-4597 ◽

2020 ◽

Author(s):

Patrick Dewald ◽

Justin Shenolikar ◽

Nils Friedrich ◽

Franz Rohrer ◽

Ralf Tillmann ◽

...

Keyword(s):

Oxidation Products ◽

Research Centre ◽

Biogenic Emissions ◽

Organic Nitrates ◽

Peroxy Radicals ◽

Experimental Conditions ◽

Mixing Ratios ◽

Volatile Organic ◽

Isoprene Oxidation ◽

Chamber Studies

Isoprene is the major volatile organic compound that is released into the environment via biogenic emissions and its oxidation can result in formation of secondary organic aerosol (SOA). Although isoprene emission occurs mainly at daytime, it can accumulate at nighttime and be oxidized by the nitrate radical (NO3) to form organic nitrates that can partition to the particle phase. A detailed understanding of the reaction between isoprene and NO3 is thus required to predict its role in e.g. NOX lifetimes and SOA formation.The reaction between NO3 and isoprene was investigated under varying experimental conditions (high or low RO2/HO2, temperature, humidity, seed aerosols) during the NO3ISOP campaign at the atmospheric simulation chamber SAPHIR of the research centre in J&#252;lich (Germany). Direct measurement of the NO3 reactivity was carried out with means of a flowtube coupled to a cavity-ring-down spectroscopy (FT-CRDS) setup which enabled the evolution of the NO3 lifetime during the isoprene oxidation process to be monitored.By comparing direct NO3 reactivity measurements with those calculated from VOC mixing ratios and those calculated from a stationary-state analysis we identify the contributions of isoprene, secondary oxidation products and peroxy radicals to NO3 losses.

Download Full-text

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.

Download Full-text

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.

Download Full-text

Large estragole fluxes from oil palms in Borneo

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-1517-2010 ◽

2010 ◽

Vol 10 (1) ◽

pp. 1517-1557 ◽

Cited By ~ 3

Author(s):

P. K. Misztal ◽

S. M. Owen ◽

A. B. Guenther ◽

R. Rasmussen ◽

C. Geron ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Oil Palm ◽

Ponderosa Pine ◽

Elaeis Guineensis ◽

Ambient Air ◽

Biogenic Emissions ◽

Main Peak ◽

Aerosol Formation ◽

Mixing Ratios ◽

Oil Palms

Abstract. During two field campaigns (OP3 and ACES), which ran in Borneo in 2008, we measured large emissions of estragole (methyl chavicol; IUPAC systematic name 1-allyl-4-methoxybenzene; CAS number 140-67-0) in ambient air above oil palm canopies (0.81 mg m−2 h−1 and 3.2 ppbv for mean midday fluxes and mixing ratios, respectively) and subsequently from flower enclosures. However, we did not detect this compound at a nearby rainforest. Estragole is a known attractant of the African oil palm weevil (Elaeidobius kamerunicus), which pollinates oil palms (Elaeis guineensis). There has been recent interest in the biogenic emissions of estragole but it is normally not included in atmospheric models of biogenic emissions and atmospheric chemistry despite its relatively high potential for secondary organic aerosol formation from photooxidation and high reactivity with OH radical. We report the first direct canopy-scale measurements of estragole fluxes from tropical oil palms by the virtual disjunct eddy covariance technique and compare them with previously reported data for estragole emissions from Ponderosa pine. Flowers, rather than leaves, appear to be the main source of estragole from oil palms; we derive a global estimate of estragole emissions from oil palm plantations of ~0.5 Tg y−1. The observed ecosystem mean fluxes (0.44 mg m−2 h−1) and mean ambient volume mixing ratios (3.0 ppbv) of estragole are the highest reported so far. The value for midday mixing ratios is not much different from the total average as, unlike other VOCs (e.g. isoprene), the main peak occurred in the evening rather than in the middle of the day. Despite this, we show that the estragole flux can be parameterised using a combination of a modified G06 algorithm for emission and a canopy resistance approach for deposition. However, the model underestimates the afternoon peak even though a similar approach works well for isoprene. Our measurements suggest that this biogenic compound may have an impact on regional atmospheric chemistry that previously has not been accounted for in models and could become more important in the future due to expansion of the areas of oil palm plantation.

Download Full-text

Cryptogamic organisms are a substantial source and sink for volatile organic compounds in the Amazon region

Communications Earth & Environment ◽

10.1038/s43247-021-00328-y ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Achim Edtbauer ◽

Eva Y. Pfannerstill ◽

Ana Paula Pires Florentino ◽

Cybelli G. G. Barbosa ◽

Emilio Rodriguez-Caballero ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Atmospheric Chemistry ◽

Forest Canopy ◽

Oxidation Products ◽

Atmospheric Oxidation ◽

Tropical Rainforests ◽

Volatile Organic ◽

Flux Measurements ◽

Made In

AbstractCryptogamic organisms such as bryophytes and lichens cover most surfaces within tropical forests, yet their impact on the emission of biogenic volatile organic compounds is unknown. These compounds can strongly influence atmospheric oxidant levels as well as secondary organic aerosol concentrations, and forest canopy leaves have been considered the dominant source of these emissions. Here we present cuvette flux measurements, made in the Amazon rainforest between 2016–2018, and show that common bryophytes emit large quantities of highly reactive sesquiterpenoids and that widespread lichens strongly uptake atmospheric oxidation products. A spatial upscaling approach revealed that cryptogamic organisms emit sesquiterpenoids in quantities comparable to current canopy attributed estimates, and take up atmospheric oxidation products at rates comparable to hydroxyl radical chemistry. We conclude that cryptogamic organisms play an important and hitherto overlooked role in atmospheric chemistry above and within tropical rainforests.

Download Full-text

Large estragole fluxes from oil palms in Borneo

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-4343-2010 ◽

2010 ◽

Vol 10 (9) ◽

pp. 4343-4358 ◽

Cited By ~ 47

Author(s):

P. K. Misztal ◽

S. M. Owen ◽

A. B. Guenther ◽

R. Rasmussen ◽

C. Geron ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Oil Palm ◽

Ponderosa Pine ◽

Elaeis Guineensis ◽

Ambient Air ◽

Biogenic Emissions ◽

Main Peak ◽

Aerosol Formation ◽

Mixing Ratios ◽

Oil Palms

Abstract. During two field campaigns (OP3 and ACES), which ran in Borneo in 2008, we measured large emissions of estragole (methyl chavicol; IUPAC systematic name 1-allyl-4-methoxybenzene; CAS number 140-67-0) in ambient air above oil palm canopies (0.81 mg m−2 h−1 and 3.2 ppbv for mean midday fluxes and mixing ratios respectively) and subsequently from flower enclosures. However, we did not detect this compound at a nearby rainforest. Estragole is a known attractant of the African oil palm weevil (Elaeidobius kamerunicus), which pollinates oil palms (Elaeis guineensis). There has been recent interest in the biogenic emissions of estragole but it is normally not included in atmospheric models of biogenic emissions and atmospheric chemistry despite its relatively high potential for secondary organic aerosol formation from photooxidation and high reactivity with OH radical. We report the first direct canopy-scale measurements of estragole fluxes from tropical oil palms by the virtual disjunct eddy covariance technique and compare them with previously reported data for estragole emissions from Ponderosa pine. Flowers, rather than leaves, appear to be the main source of estragole from oil palms; we derive a global estimate of estragole emissions from oil palm plantations of ~0.5 Tg y−1. The observed ecosystem mean fluxes (0.44 mg m−2 h−1) and mean ambient volume mixing ratios (3.0 ppbv) of estragole are the highest reported so far. The value for midday mixing ratios is not much different from the total average as, unlike other VOCs (e.g. isoprene), the main peak occurred in the evening rather than in the middle of the day. Despite this, we show that the estragole flux can be parameterised using a modified G06 algorithm for emission. However, the model underestimates the afternoon peak even though a similar approach works well for isoprene. Our measurements suggest that this biogenic compound may have an impact on regional atmospheric chemistry that previously has not been accounted for in models and could become more important in the future due to expansion of the areas of oil palm plantation.

Download Full-text

Speciation of OH reactivity above the canopy of an isoprene-dominated forest

10.5194/acp-2015-1006 ◽

2016 ◽

Cited By ~ 2

Author(s):

J. Kaiser ◽

K. M. Skog ◽

K. Baumann ◽

S. B. Bertman ◽

S. B. Brown ◽

...

Keyword(s):

Oxidation Products ◽

Ozone Production ◽

Biogenic Emissions ◽

Absolute Value ◽

Reactive Carbon ◽

Volatile Organic ◽

Measurement Suite ◽

Primary Emissions ◽

Comprehensive Measurement ◽

Good Agreement

Abstract. Measurements of OH reactivity, the inverse lifetime of the OH-radical, can provide a top-down estimate of the total amount of reactive carbon in an airmass. Because OH reactivity is tied to the RO2 production rate, the absolute value of OH reactivity has direct implications for ozone production. Additionally, as molecular structure determines volatility, the speciation of reactivity affects the production of secondary organic aerosol (SOA). Several studies have focused on the agreement of measured and calculated or modeled OH reactivity above and within the canopy of isoprene-dominated forests, as well as the relative contributions of volatile organic compounds (VOCs) and oxidized VOCs (OVOCs). Drawing definitive conclusions about the identity of the missing OH reactivity has been limited by the availability of VOC and OVOC measurements. In this work, using a comprehensive measurement suite, we examine the measured and modeled OH reactivity above an isoprene-dominated forest in the South East United States during the 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign. We find good agreement between measured and modeled OH reactivity, with the largest contribution consistently coming from primary biogenic emissions. In contrast, there are small but significant discrepancies in the increase in OH reactivity per isoprene. As the model typically overestimates OVOCs, we do not attribute this discrepancy to unmeasured oxidation products. Instead, we suggest that unmeasured primary emissions may influence the OH reactivity at this site.

Download Full-text