scholarly journals Urban flux measurements reveal a large pool of oxygenated volatile organic compound emissions

2018 ◽  
Vol 115 (6) ◽  
pp. 1186-1191 ◽  
Author(s):  
T. Karl ◽  
M. Striednig ◽  
M. Graus ◽  
A. Hammerle ◽  
G. Wohlfahrt
Keyword(s):  
Atmospheric Chemistry ◽  
Transfer Reaction ◽  
Organic Aerosol ◽  
Proton Transfer Reaction ◽  
Emission Sources ◽  
Large Pool ◽  
Volatile Organic ◽  
Emission Fluxes ◽  
Flux Measurements ◽  
Volatile Organic Compound Emissions

Atmospheric chemistry is fueled by a large annual influx of nonmethane volatile organic compounds (NMVOC). These compounds influence ozone formation, lead to secondary organic aerosol production, and play a significant role for the oxidizing capacity of the atmosphere. The anthropogenic NMVOC budget is considerably uncertain due to the diversity of urban emission sources. Here, we present comprehensive observations of urban NMVOC eddy covariance fluxes using a newly designed proton-transfer-reaction quadrupole interface time-of-flight mass spectrometer. We found emission fluxes of a surprisingly large pool of oxygenated NMVOCs (OVOCs) with an appreciable fraction of higher oxidized OVOCs that cannot be explained by known fast photochemical turnaround or current primary emission estimates. Measured OVOC/NMVOC bulk flux ratios are two to four times higher than inferred from aggregated anthropogenic emission inventories. Extrapolating these results would double the global anthropogenic NMVOC flux. In view of globally accelerating urbanization, our study highlights the need to reevaluate the influence of anthropogenic NMVOC on atmospheric chemistry, human health, and the climate system.

scholarly journals Eddy covariance emission and deposition flux measurements using proton transfer reaction-time of flight-mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

2012 ◽  
Vol 12 (8) ◽  
pp. 20435-20482 ◽  
Author(s):  
J.-H. Park ◽  
A. H. Goldstein ◽  
J. Timkovsky ◽  
S. Fares ◽  
R. Weber ◽  
...  
Keyword(s):  
Reaction Time ◽  
Proton Transfer ◽  
Organic Compounds ◽  
Transfer Reaction ◽  
Vertical Gradient ◽  
Proton Transfer Reaction ◽  
Volatile Organic ◽  
Flux Measurements ◽  
Ion Species ◽  
Tof Ms

Abstract. During summer 2010, a proton transfer reaction-time of flight-mass spectrometer (PTR-TOF-MS) and a standard proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m Δ m−1) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e. co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 μg C m−2 h−1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 μg C m−2 h−1) and methanol (m/z 33.032, 18%, 72 μg C m−2 h−1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 μg C m−2 h−1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 μg C m−2 h−1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 μg C m−2 h−1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 μg C m−2 h−1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7.1 μg C m−2 h−1), and m/z 69.071 (isoprene + 2-methyl-3-butene-2-ol, 1.8%, 5.3 μg C m−2 h−1). Low levels of emission and/or deposition (<1.6% for each, 5.8% in total flux) were observed for the additional reported masses. Overall, our results show that EC flux measurements using PTR-TOF-MS is a powerful new tool for characterizing the biosphere-atmosphere exchange including both emission and deposition for a large range of BVOC and their oxidation products.

scholarly journals Eddy covariance emission and deposition flux measurements using proton transfer reaction – time of flight – mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

2013 ◽  
Vol 13 (3) ◽  
pp. 1439-1456 ◽  
Author(s):  
J.-H. Park ◽  
A. H. Goldstein ◽  
J. Timkovsky ◽  
S. Fares ◽  
R. Weber ◽  
...  
Keyword(s):  
Reaction Time ◽  
Proton Transfer ◽  
Organic Compounds ◽  
Transfer Reaction ◽  
Vertical Gradient ◽  
Proton Transfer Reaction ◽  
Volatile Organic ◽  
Flux Measurements ◽  
Ion Species ◽  
Tof Ms

Abstract. During summer 2010, a proton transfer reaction – time of flight – mass spectrometer (PTR-TOF-MS) and a quadrupole proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m/Δm) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e., co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 μg C m−2 h−1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 μg C m−2 h−1) and methanol (m/z 33.032, 18%, 72 μg C m−2 h−1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 μg C m−2 h−1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 μg C m−2 h−1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 μg C m−2 h−1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 μg C m−2 h−1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7.1 μg C m−2 h−1), and m/z 69.071 (isoprene + 2-methyl-3-butene-2-ol, 1.8%, 5.3 μg C m−2 h−1). Low levels of emission and/or deposition (<1.6% for each, 5.8% in total flux) were observed for the additional reported masses. Overall, our results show that EC flux measurements using PTR-TOF-MS is a powerful new tool for characterizing the biosphere-atmosphere exchange including both emission and deposition for a large range of BVOC and their oxidation products.

scholarly journals Temporal variation of VOC fluxes measured with PTR-TOF above a boreal forest

2017 ◽  
Author(s):  
Simon Schallhart ◽  
Pekka Rantala ◽  
Maija K. Kajos ◽  
Juho Aalto ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Boreal Forest ◽  
Mass Spectrometer ◽  
Indirect Method ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Quadrupole Mass ◽  
Volatile Organic ◽  
Flux Measurements ◽  
Norway Spruce Forest

Abstract. Between April and June 2013 fluxes of volatile organic compounds (VOCs) were measured in a Scots pine and Norway spruce forest using the eddy covariance (EC) method with a proton transfer reaction time of flight (PTR-TOF) mass spectrometer. The observations were performed above a boreal forest at the SMEAR II site in Southern Finland. We found a total of 25 different compounds with exchange and investigated their seasonal variations from spring to summer. The majority of the net VOC flux was comprised of methanol, monoterpenes, acetone and butene. The VOC emissions followed a seasonal trend, the released amount increased from spring to summer. Only a three compounds were emitted in April while in June emissions of some 19 VOCs were observed. During the measurements in April, the emissions were dominated by butene, while in May and June methanol was the most emitted compound. The main source of methanol is likely the growth of new biomass. During a 21-day period in June, the net VOC flux was 2.3 nmol m−2 s−1. This is on the lower end of PTR-TOF flux measurements from other ecosystems, which range from 2 to 10 nmol m−2 s−1. The EC flux results were compared with surface layer profile measurements, an indirect method using a proton transfer reaction quadrupole mass spectrometer, which is permanently installed at the SMEAR II site was used. For most of the compounds the fluxes, measured with the two different methods, agreed well

scholarly journals Aspectos micrometeorológicos da emissão de monoterpenos em uma floresta na Amazônia central

2018 ◽  
Vol 40 ◽  
pp. 150 ◽  
Author(s):  
Sarah Batalha ◽  
Jeong-Hoo Park ◽  
Eliane Alves ◽  
Raoni Santana ◽  
Roger Seco ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Amazon Basin ◽  
Transfer Reaction ◽  
Sonic Anemometer ◽  
Brazilian Amazon ◽  
Proton Transfer Reaction ◽  
Mixing Ratio ◽  
Forest Region ◽  
Central Amazonia ◽  
Volatile Organic

This research aimed to present results about the mixing ratio and flux of monoterpenes at a forest region of the Brazilian Amazon. It was used micrometeorology instrumentation (using a Sonic Anemometer) and analytical chemistry by a Proton Transfer Reaction - Time of Flight - Mass Spectrometer, PTR-ToF-MS. The calibration of the spectrometer was performed regularly using a gravimetric mix of standard gas containing different masses of volatile organic compounds. The results showed average mixing ration of monoterpenes of 0.185 ppbv and maximum emission flux of 1.495 mg m-2 h-1. It was concluded that this region presented a significant emission of monoterpenes in relation to another tropical forest in central Amazonia, evidencing the needing to improve studies about atmospheric chemistry in different forests of the Amazon Basin.

scholarly journals Annual cycle of volatile organic compound exchange between a boreal pine forest and the atmosphere

2015 ◽  
Vol 12 (12) ◽  
pp. 9543-9586
Author(s):  
P. Rantala ◽  
J. Aalto ◽  
R. Taipale ◽  
T. M. Ruuskanen ◽  
J. Rinne
Keyword(s):  
Boreal Forests ◽  
Transfer Reaction ◽  
Similarity Theory ◽  
Proton Transfer Reaction ◽  
Monthly Basis ◽  
Deposition Fluxes ◽  
Water Films ◽  
Volatile Organic ◽  
Flux Measurements

Abstract. Long-term flux measurements of volatile organic compounds (VOC) over boreal forests are rare, although the forests are known to emit considerable amounts of VOCs into the atmosphere. Thus, we measured fluxes of several VOCs and oxygenated VOCs over a Scots pine dominated boreal forest semi-continuously between May 2010 and December 2013. The VOC profiles were obtained with a proton-transfer-reaction mass-spectrometry, and the fluxes were calculated using vertical concentration profiles and the surface layer profile method connected to the Monin-Obukhov similarity theory. In total fluxes that differed significantly from zero on a monthly basis were observed for 14 out 27 measured masses. Monoterpenes had the highest net emission in all seasons and statistically significant positive fluxes were detected from March until November. Other important compounds emitted were methanol, ethanol/formic acid, acetone and isoprene/MBO. Oxygenated VOCs showed also deposition fluxes that were statistically different from zero. Isoprene/methylbutenol and monoterpene fluxes followed well the traditional isoprene algorithm and the hybrid algorithm, respectively. Emission potentials of monoterpenes were largest in late spring and fall which was possibly driven by growth processes and decaying of soil litter, respectively. Conversely, largest emission potentials of isoprene/methylbutenol were found in July. Thus, we concluded that most of the emissions of m/z 69 at the site consisted of isoprene that originated from broadleaved trees. Methanol had deposition fluxes especially before sunrise. This can be connected to water films on surfaces. Based on this assumption, we were able to build an empirical algorithm for bi-directional methanol exchange that described both emission term and deposition term. Methanol emissions were highest in May and June and deposition level increased towards fall, probably as a result of increasing relative humidity levels leading to predominance of deposition.

scholarly journals Temporal variation of VOC fluxes measured with PTR-TOF above a boreal forest

2018 ◽  
Vol 18 (2) ◽  
pp. 815-832 ◽  
Author(s):  
Simon Schallhart ◽  
Pekka Rantala ◽  
Maija K. Kajos ◽  
Juho Aalto ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Boreal Forest ◽  
Mass Spectrometer ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Quadrupole Mass ◽  
Volatile Organic ◽  
Flux Measurements ◽  
Norway Spruce Forest ◽  
Measurement Period

Abstract. Between April and June 2013 fluxes of volatile organic compounds (VOCs) were measured in a Scots pine and Norway spruce forest using the eddy covariance (EC) method with a proton transfer reaction time-of-flight (PTR-TOF) mass spectrometer. The observations were performed above a boreal forest at the SMEAR II site in southern Finland.We found a total of 25 different compounds with exchange and investigated their seasonal variations from spring to summer. The majority of the net VOC flux was comprised of methanol, monoterpenes, acetone and butene + butanol. The butene + butanol emissions were concluded to not originate from the forest and, therefore, be anthropogenic. The VOC exchange followed a seasonal trend and the emissions increased from spring to summer. Only three compounds were emitted during the snowmelt while in summer emissions of some 19 VOCs were observed. During the measurement period in April, the emissions were dominated by butene + butanol, while during the start of the growing season and in summer, methanol was the most emitted compound. The main source of methanol was likely the growth of new biomass. During a 21-day period in June, the net VOC flux was 2.1 nmol m−2 s−1. This is on the lower end of PTR-TOF flux measurements from other ecosystems, which range from 2 to 10 nmol m−2 s−1. The EC flux results were compared with surface layer profile measurements, using a proton transfer reaction quadrupole mass spectrometer, which is permanently installed at the SMEAR II site. For the major compounds, the fluxes measured with the two different methods agreed well.

scholarly journals Annual cycle of volatile organic compound exchange between a boreal pine forest and the atmosphere

2015 ◽  
Vol 12 (19) ◽  
pp. 5753-5770 ◽  
Author(s):  
P. Rantala ◽  
J. Aalto ◽  
R. Taipale ◽  
T. M. Ruuskanen ◽  
J. Rinne
Keyword(s):  
Boreal Forests ◽  
Transfer Reaction ◽  
Similarity Theory ◽  
Proton Transfer Reaction ◽  
Monthly Basis ◽  
Deposition Fluxes ◽  
Water Films ◽  
Volatile Organic ◽  
Flux Measurements

Abstract. Long-term flux measurements of volatile organic compounds (VOC) over boreal forests are rare, although the forests are known to emit considerable amounts of VOCs into the atmosphere. Thus, we measured fluxes of several VOCs and oxygenated VOCs over a Scots-pine-dominated boreal forest semi-continuously between May 2010 and December 2013. The VOC profiles were obtained with a proton transfer reaction mass spectrometry, and the fluxes were calculated using vertical concentration profiles and the surface layer profile method connected to the Monin-Obukhov similarity theory. In total fluxes that differed significantly from zero on a monthly basis were observed for 13 out of 27 measured masses. Monoterpenes had the highest net emission in all seasons and statistically significant positive fluxes were detected from March until October. Other important compounds emitted were methanol, ethanol+formic acid, acetone and isoprene+methylbutenol. Oxygenated VOCs showed also deposition fluxes that were statistically different from zero. Isoprene+methylbutenol and monoterpene fluxes followed well the traditional isoprene algorithm and the hybrid algorithm, respectively. Emission potentials of monoterpenes were largest in late spring and autumn which was possibly driven by growth processes and decaying of soil litter, respectively. Conversely, largest emission potentials of isoprene+methylbutenol were found in July. Thus, we concluded that most of the emissions of m/z 69 at the site consisted of isoprene that originated from broadleaved trees. Methanol had deposition fluxes especially before sunrise. This can be connected to water films on surfaces. Based on this assumption, we were able to build an empirical algorithm for bi-directional methanol exchange that described both emission term and deposition term. Methanol emissions were highest in May and June and deposition level increased towards autumn, probably as a result of increasing relative humidity levels leading to predominance of deposition.

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