scholarly journals Emissions of isoprenoids and oxygenated biogenic volatile organic compounds from a New England mixed forest

2011 ◽  
Vol 11 (10) ◽  
pp. 4807-4831 ◽  
Author(s):  
K. A. McKinney ◽  
B. H. Lee ◽  
A. Vasta ◽  
T. V. Pho ◽  
J. W. Munger
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Forest Canopy ◽  
Emission Rate ◽  
Mixed Forest ◽  
Emission Rates ◽  
Biogenic Volatile Organic Compounds ◽  
Methanol Production ◽  
Short Period ◽  
Volatile Organic

Abstract. Fluxes of biogenic volatile organic compounds, including isoprene, monoterpenes, and oxygenated VOCs measured above a mixed forest canopy in central Massachusetts during the 2005 and 2007 growing seasons are reported. Mixing ratios were measured using proton transfer reaction mass spectrometry (PTR-MS) and fluxes computed by the disjunct eddy covariance technique. Isoprene was by far the predominant BVOC emitted at this site, with summer mid-day average fluxes of 5.3 and 4.4 mg m−2 hr−1 in 2005 and 2007, respectively. In comparison, mid-day average fluxes of monoterpenes were 0.21 and 0.15 mg m−2 hr−1 in each of these years. On short times scales (days), the diel pattern in emission rate compared well with a standard emission algorithm for isoprene. The general shape of the seasonal cycle and the observed decrease in isoprene emission rate in early September was, however, not well captured by the model. Monoterpene emission rates exhibited dependence on light as well as temperature, as determined from the improved fit to the observations obtained by including a light-dependent term in the model. The mid-day average flux of methanol from the canopy was 0.14 mg m−2 hr−1 in 2005 and 0.19 mg m−2 hr−1 in 2007, but the maximum flux was observed in spring (29 May 2007), when the flux reached 1.0 mg m−2 hr−1. This observation is consistent with enhanced methanol production during leaf expansion. Summer mid-day fluxes of acetone were 0.15 mg m−2 hr−1 during a short period in 2005, but only 0.03 mg m−2 h−1 averaged over 2007. Episodes of negative fluxes of oxygenated VOCs, particularly acetone, were observed periodically, especially in 2007. Thus, deposition within the canopy could help explain the low season-averaged flux of acetone in 2007. Fluxes of species of biogenic origin at mass-to-charge ($m/z$) ratios of 73 (0.05 mg m−2 hr−1 in 2005; 0.03 mg m−2 hr−1 in 2007) and 153 (5 μg m−2 hr−1 in 2007), possibly corresponding to methyl ethyl ketone and an oxygenated terpene or methyl salicylate, respectively, were also observed.

scholarly journals Emissions of isoprenoids and oxygenated biogenic volatile organic compounds from a New England mixed forest

2010 ◽  
Vol 10 (11) ◽  
pp. 28565-28633
Author(s):  
K. A. McKinney ◽  
B. H. Lee ◽  
A. Vasta ◽  
T. V. Pho ◽  
J. W. Munger
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Forest Canopy ◽  
Emission Rate ◽  
Mixed Forest ◽  
Emission Rates ◽  
Biogenic Volatile Organic Compounds ◽  
Methanol Production ◽  
Short Period ◽  
Volatile Organic

Abstract. Fluxes of biogenic volatile organic compounds, including isoprene, monoterpenes, and oxygenated VOCs measured above a mixed forest canopy in western Massachusetts during the 2005 and 2007 growing seasons are reported. Measurements were made using proton transfer reaction mass spectrometry (PTR-MS) and converted to fluxes using the disjunct eddy covariance technique. Isoprene was by far the predominant BVOC emitted at this site, with summer mid-day average fluxes of 5.3 and 4.4 mg m−2 h−1 in 2005 and 2007, respectively. In comparison, mid-day average fluxes of monoterpenes were 0.21 and 0.15 mg m−2 h−1 in each of these years. On short times scales (days), the diel pattern in emission rate compared well with a standard emission algorithm for isoprene. The general shape of the seasonal cycle and the observed decrease in isoprene emission rate in early September was, however, not well captured by the model. Monoterpene emission rates exhibited dependence on light as well as temperature, as determined from the improved fit to the observations obtained by including a light-dependent term in the model. The mid-day average flux of methanol from the canopy was 0.14 mg m−2 h−1 in 2005 and 0.19 mg m−2 h−1 in 2007, but the maximum flux was observed in spring (29 May 2007), when the flux reached 1.0 mg m−2 h−1. This observation is consistent with enhanced methanol production during leaf expansion. Summer mid-day fluxes of acetone were 0.15 mg m−2 h−1 during a short period in 2005, but only 0.03 mg m−2 h−1 averaged over 2007. Episodes of negative fluxes of oxygenated VOCs, particularly acetone, were observed periodically, especially in 2007. Thus, deposition within the canopy could help explain the low season-averaged flux of acetone in 2007. Fluxes of species of biogenic origin at mass-to-charge (m/z) ratios of 73 (0.05 mg m−2 h−1 in 2005; 0.03 mg m−2 h−1 in 2007) and 153 (5 μg m−2 h−1 in 2007), possibly corresponding to methyl ethyl ketone and an oxygenated terpene, respectively, were also observed.

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

2010 ◽  
Vol 10 (13) ◽  
pp. 6215-6235 ◽  
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.

scholarly journals Simulations of atmospheric OH, O<sub>3</sub> and NO<sub>3</sub> reactivities within and above the boreal forest

2015 ◽  
Vol 15 (7) ◽  
pp. 3909-3932 ◽  
Author(s):  
D. Mogensen ◽  
R. Gierens ◽  
J. N. Crowley ◽  
P. Keronen ◽  
S. Smolander ◽  
...  
Keyword(s):  
Steady State ◽  
Volatile Organic Compounds ◽  
Boreal Forest ◽  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Inorganic Compounds ◽  
Spectral Irradiance ◽  
Biogenic Volatile Organic Compounds ◽  
Short Period ◽  
Volatile Organic

Abstract. Using the 1-D atmospheric chemistry transport model SOSAA, we have investigated the atmospheric reactivity of a boreal forest ecosystem during the HUMPPA-COPEC-10 campaign (summer 2010, at SMEAR~II in southern Finland). For the very first time, we present vertically resolved model simulations of the NO3 and O3 reactivity (R) together with the modelled and measured reactivity of OH. We find that OH is the most reactive oxidant (R ∼ 3 s-1) followed by NO3 (R ∼ 0.07 s-1) and O3 (R ∼ 2 × 10-5s-1). The missing OH reactivity was found to be large in accordance with measurements (∼ 65%) as would be expected from the chemical subset described in the model. The accounted OH radical sinks were inorganic compounds (∼ 41%, mainly due to reaction with CO), emitted monoterpenes (∼ 14%) and oxidised biogenic volatile organic compounds (∼ 44%). The missing reactivity is expected to be due to unknown biogenic volatile organic compounds and their photoproducts, indicating that the true main sink of OH is not expected to be inorganic compounds. The NO3 radical was found to react mainly with primary emitted monoterpenes (∼ 60%) and inorganic compounds (∼ 37%, including NO2). NO2 is, however, only a temporary sink of NO3 under the conditions of the campaign (with typical temperatures of 20–25 °C) and does not affect the NO3 concentration. We discuss the difference between instantaneous and steady-state reactivity and present the first boreal forest steady-state lifetime of NO3 (113 s). O3 almost exclusively reacts with inorganic compounds (∼ 91%, mainly NO, but also NO2 during night) and less with primary emitted sesquiterpenes (∼ 6%) and monoterpenes (∼ 3%). When considering the concentration of the oxidants investigated, we find that OH is the oxidant that is capable of removing organic compounds at a faster rate during daytime, whereas NO3 can remove organic molecules at a faster rate during night-time. O3 competes with OH and NO3 during a short period of time in the early morning (around 5 a.m. local time) and in the evening (around 7–8 p.m.). As part of this study, we developed a simple empirical parameterisation for conversion of measured spectral irradiance into actinic flux. Further, the meteorological conditions were evaluated using radiosonde observations and ground-based measurements. The overall vertical structure of the boundary layer is discussed, together with validation of the surface energy balance and turbulent fluxes. The sensible heat and momentum fluxes above the canopy were on average overestimated, while the latent heat flux was underestimated.

scholarly journals Oxidation of Volatile Organic Compounds as the Major Source of Formic Acid in a Mixed Forest Canopy

2019 ◽  
Vol 46 (5) ◽  
pp. 2940-2948 ◽  
Author(s):  
Hariprasad D. Alwe ◽  
Dylan B. Millet ◽  
Xin Chen ◽  
Jonathan D. Raff ◽  
Zachary C. Payne ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Formic Acid ◽  
Organic Compounds ◽  
Forest Canopy ◽  
Mixed Forest ◽  
Volatile Organic

scholarly journals Emissions of biogenic volatile organic compounds and subsequent formation of secondary organic aerosols in a <I>Larix kaempferi</I> forest

2015 ◽  
Vol 15 (20) ◽  
pp. 12029-12041 ◽  
Author(s):  
T. Mochizuki ◽  
Y. Miyazaki ◽  
K. Ono ◽  
R. Wada ◽  
Y. Takahashi ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Forest Floor ◽  
Forest Canopy ◽  
Oxidation Products ◽  
Larix Kaempferi ◽  
Vertical Profiles ◽  
Biogenic Volatile Organic Compounds ◽  
Subsequent Formation ◽  
Volatile Organic

Abstract. We conducted simultaneous measurements of concentrations and above-canopy fluxes of isoprene and α-pinene, along with their oxidation products in aerosols in a Larix kaempferi (Japanese larch) forest in summer 2012. Vertical profiles of isoprene showed the maximum concentration near the forest floor with a peak around noon, whereas oxidation products of isoprene, i.e., methacrolein (MACR) and methyl vinyl ketone (MVK), showed higher concentrations near the canopy level of the forest. The vertical profile suggests large emissions of isoprene near the forest floor, likely due to Dryopteris crassirhizoma (a fern species), and the subsequent reaction within the canopy. The concentrations of α-pinene also showed highest values near the forest floor, with maximums in the early morning and late afternoon. The vertical profiles of α-pinene suggest its large emissions from soil and litter in addition to emissions from L. kaempferi leaves at the forest site. Isoprene and its oxidation products in aerosols exhibited similar diurnal variations within the forest canopy, providing evidence of secondary organic aerosol (SOA) formation via oxidation of isoprene most likely emitted from the forest floor. Although high abundance of α-pinene was observed in the morning, its oxidation products in aerosols showed peaks in daytime, due to a time lag between the emission and atmospheric reactions of α-pinene to form SOA. Positive matrix factorization (PMF) analysis indicated that anthropogenic influence is the most important factor contributing to the elevated concentrations of molecular oxidation products of isoprene- (> 64 %) and α-pinene-derived SOA (> 57 %). The combination of the measured fluxes and vertical profiles of biogenic volatile organic compounds (BVOCs) suggests that the inflow of anthropogenic precursors/aerosols likely enhanced the formation of both isoprene SOA and α-pinene SOA within the forest canopy even when the BVOC flux was relatively low. This study highlights the importance of intra-canopy processes that promote biogenic SOA formation in the presence of significant inflow of oxidants together with anthropogenic aerosols and their precursors.

scholarly journals Emissions of biogenic volatile organic compounds and subsequent formation of secondary organic aerosols in a <i>Larix kaempferi</i> forest

2015 ◽  
Vol 15 (7) ◽  
pp. 10739-10771 ◽  
Author(s):  
T. Mochizuki ◽  
Y. Miyazaki ◽  
K. Ono ◽  
R. Wada ◽  
Y. Takahashi ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Forest Floor ◽  
Forest Canopy ◽  
Oxidation Products ◽  
Larix Kaempferi ◽  
Vertical Profiles ◽  
Biogenic Volatile Organic Compounds ◽  
Subsequent Formation ◽  
Volatile Organic

Abstract. We conducted simultaneous measurements of concentrations and above-canopy fluxes of isoprene and α-pinene, along with their oxidation products in aerosols in a Larix kaempferi (Japanese larch) forest in summer 2012. Vertical profiles of isoprene showed the maximum concentration near the forest floor with a peak around noon, whereas oxidation products of isoprene, i.e., methacrolein (MACR) and methyl vinyl ketone (MVK), showed higher concentrations near the canopy level of the forest. The vertical profile suggests large emissions of isoprene near the forest floor, likely due to Dryopteris crassirhizoma (a fern species), and the subsequent reaction within the canopy. The concentrations of α-pinene also showed highest values near the forest floor with maximums in the early morning and late afternoon. The vertical profiles of α-pinene suggest its large emissions from soil and litter in addition to emissions from L. kaempferi leaves at the forest site. Isoprene and its oxidation products in aerosols exhibited similar diurnal variations within the forest canopy, providing evidence for secondary organic aerosol (SOA) formation via oxidation of isoprene most likely emitted from the forest floor. Although high abundance of α-pinene was observed in the morning, its oxidation products in aerosols showed peaks in daytime, due to a time lag between the emission and atmospheric reactions of α-pinene to form SOA. Positive matrix factorization (PMF) analysis indicated that anthropogenic influence is the most important factor contributing to the elevated concentrations of molecular oxidation products of isoprene- (> 64%) and α-pinene-derived SOA (> 57%). The combination of the measured fluxes and vertical profiles of biogenic volatile organic compounds (BVOCs) suggests that the inflow of anthropogenic precursors/aerosols likely enhanced the formation of both isoprene- and α-pinene-SOA within the forest canopy even when the BVOC flux was relatively low. This study highlights the importance of intra-canopy processes that promote biogenic SOA formation in the presence of significant inflow of anthropogenic aerosols and their precursors.

scholarly journals Concentrations and fluxes of biogenic volatile organic compounds above a Mediterranean macchia ecosystem in Western Italy

2009 ◽  
Vol 6 (1) ◽  
pp. 2183-2216 ◽  
Author(s):  
B. Davison ◽  
R. Taipale ◽  
B. Langford ◽  
P. Misztal ◽  
S. Fares ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Three Dimensional ◽  
Proton Transfer Reaction ◽  
Emission Rates ◽  
Biogenic Volatile Organic Compounds ◽  
Eddy Covariance Method ◽  
Mixing Ratios ◽  
Sonic Anemometers ◽  
Volatile Organic

Abstract. Emission rates and concentrations of biogenic volatile organic compounds (BVOCs) were measured at a Mediterranean coastal site at Castelporziano, approximately 25 km south-west of Rome, between 7 May and 3 June 2007, as part of the ACCENT-VOCBAS field campaign on biosphere-atmosphere interactions. Concentrations and emission rates were measured using the disjunct eddy covariance method utilizing three different proton transfer reaction mass spectrometers (PTR-MS) for BVOC mixing ratio measurements and sonic anemometers for three-dimensional high-frequency wind measurements. Depending on the measurement period and the instrument, the median volume mixing ratios were 1.6–3.5 ppbv for methanol, 0.4–1.5 ppbv for acetaldehyde, 1.0–2.5 ppbv for acetone, 0.10–0.17 ppbv for isoprene, and 0.18–0.30 ppbv for monoterpenes. A diurnal cycle in mixing ratios was apparent with daytime maxima for methanol, acetaldehyde, acetone, and isoprene. The median fluxes were 370–440 μg m−2 h−1 for methanol, 180–360 μg m−2 h−1 for acetaldehyde, 180–450 μg m−2 h−1 for acetone, 71–290 μg m−2 h−1 for isoprene, and 240–860 μg m−2 h−1 for monoterpenes.

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