scholarly journals Source characterization of volatile organic compounds measured by PTR-ToF-MS in Delhi, India

2020 ◽  
Author(s):  
Liwei Wang ◽  
Jay G. Slowik ◽  
Nidhi Tripathi ◽  
Deepika Bhattu ◽  
Pragati Rai ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Solid Fuel ◽  
Proton Transfer Reaction ◽  
Fuel Combustion ◽  
Source Characterization ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
Solid Fuel Combustion ◽  
Tof Ms

Abstract. Characteristics and sources of volatile organic compounds (VOCs) were investigated with highly time-resolved simultaneous measurements by two proton-transfer-reaction time-of-flight mass spectrometers (PTR-ToF-MS) at an urban and a suburban site in New Delhi, India from January to March 2018. During the measurement period, high mixing ratios of VOCs and trace gases were observed, with high nocturnal mixing ratios and strong day-night variations. The positive matrix factorization (PMF) receptor model was applied separately to the two sites, and six major factors of VOCs were identified at both sites, i.e., two factors related to traffic emissions, two to solid fuel combustion, and two secondary factors. At the urban IITD site, traffic-related emissions comprising mostly mono-aromatic compounds were the dominant sources, contributing 56.6 % of the total mixing ratio, compared to 36.0 % at the suburban MRIU site. Emissions from various solid fuel combustion processes, particularly in the night, were identified as a significant source of aromatics, phenols and furans at both sites. The secondary factors accounted for 15.9 % of the total VOC concentration at IITD and for 33.6 % at MRIU. They were dominated by oxygenated VOCs and exhibited substantially higher contributions during daytime.

scholarly journals Fluxes and concentrations of volatile organic compounds above central London, UK

2009 ◽  
Vol 9 (4) ◽  
pp. 17297-17333 ◽  
Author(s):  
B. Langford ◽  
E. Nemitz ◽  
E. House ◽  
G. J. Phillips ◽  
D. Famulari ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Traffic Density ◽  
Mixing Ratios ◽  
Oxygenated Compounds ◽  
Volatile Organic ◽  
Benzene Toluene ◽  
The Uk

Abstract. Concentrations and fluxes of eight volatile organic compounds (VOCs) were measured during October 2006 from a high telecom tower above central London, as part of the CityFlux contribution to the REPARTEE I campaign. A continuous flow disjunct eddy covariance technique with analysis by proton transfer reaction mass spectrometry was used. Daily averaged VOC mixing ratios were within the range 1–19 ppb for the oxygenated compounds (methanol, acetaldehyde and acetone) and 0.2–1.3 ppb for the aromatics (benzene, toluene and ethylbenzene). Typical VOC fluxes were in the range 0.1–1.0 mg m−2 h−1. There was a non-linear relationship between VOC fluxes and traffic density for most of the measured compounds. Traffic activity was estimated to account for approximately 70% of the aromatic compound fluxes, whereas non-traffic related sources were found to be more important for methanol and isoprene fluxes. The measured fluxes were comparable to the estimates of the UK national atmospheric emission inventory for the aromatic VOCs and CO. In contrast, fluxes of the oxygenated compounds were about three times larger than inventory estimates. For isoprene and acetonitrile this difference was many times larger. At temperatures over 25°C it is estimated that more than half the isoprene observed in central London is of biogenic origin.

scholarly journals Mixing ratios and eddy covariance flux measurements of volatile organic compounds from an urban canopy (Manchester, UK)

2008 ◽  
Vol 8 (1) ◽  
pp. 245-284 ◽  
Author(s):  
B. Langford ◽  
B. Davison ◽  
E. Nemitz ◽  
C. N. Hewitt
Keyword(s):  
Volatile Organic Compounds ◽  
Eddy Covariance ◽  
Organic Compounds ◽  
Urban Canopy ◽  
Proton Transfer Reaction ◽  
Anthropogenic Sources ◽  
Emissions Inventory ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
The Individual

Abstract. Concentrations and fluxes of six volatile organic compounds (VOC) were measured above the city of Manchester (UK) during the summer of 2006. A proton transfer reaction-mass spectrometer was used for the measurement of concentrations, and fluxes were calculated using both the disjunct and the virtual disjunct eddy covariance techniques. The two flux systems, which operated in alternate half hours, showed reasonable agreement, with R2 values ranging between 0.2 and 0.8 for the individual analytes. On average, fluxes measured in the disjunct mode were lower than those measured in the virtual mode by approximately 19%, of which at least 8% can be attributed to the differing measurement frequencies of the two systems and the subsequent attenuation of high frequency flux contributions. Observed fluxes are thought to be largely controlled by anthropogenic sources, with vehicle emissions the major contributor. However both evaporative and biogenic emissions may account for a fraction of the isoprene present. Fluxes of the oxygenated compounds were highest on average, ranging between 60–89 μg m−2 h−1, whereas the fluxes of aromatic compounds were lower, between 19–42 μg m−2 h−1. The observed fluxes of benzene were up-scaled to give a city wide emission estimate which was found to be significantly lower than that of the National Atmospheric Emissions Inventory (NAEI).

scholarly journals Source characterization of volatile organic compounds measured by proton-transfer-reaction time-of-flight mass spectrometers in Delhi, India

2020 ◽  
Vol 20 (16) ◽  
pp. 9753-9770 ◽  
Author(s):  
Liwei Wang ◽  
Jay G. Slowik ◽  
Nidhi Tripathi ◽  
Deepika Bhattu ◽  
Pragati Rai ◽  
...  
Keyword(s):  
Reaction Time ◽  
Solid Fuel ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Urban Site ◽  
Mass Spectrometers ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
Solid Fuel Combustion ◽  
Suburban Site

Abstract. Characteristics and sources of volatile organic compounds (VOCs) were investigated with highly time-resolved simultaneous measurements by two proton-transfer-reaction time-of-flight mass spectrometers (PTR-ToF-MS) at an urban and a suburban site in New Delhi, India, from January to March 2018. During the measurement period, high mixing ratios of VOCs and trace gases were observed, with high nocturnal mixing ratios and strong day–night variations. The positive matrix factorization (PMF) receptor model was applied separately to the two sites, and six major factors of VOCs were identified at both sites, i.e., two factors related to traffic emissions, two to solid fuel combustion, and two secondary factors. At the urban site, traffic-related emissions comprising mostly mono-aromatic compounds were the dominant sources, contributing 56.6 % of the total mixing ratio, compared to 36.0 % at the suburban site. Emissions from various solid fuel combustion processes, particularly in the night, were identified as a significant source of aromatics, phenols and furans at both sites. The secondary factors accounted for 15.9 % of the total VOC concentration at the urban site and for 33.6 % at the suburban site. They were dominated by oxygenated VOCs and exhibited substantially higher contributions during daytime.

scholarly journals A compact PTR-ToF-MS instrument for airborne measurements of volatile organic compounds at high spatiotemporal resolution

2014 ◽  
Vol 7 (11) ◽  
pp. 3763-3772 ◽  
Author(s):  
M. Müller ◽  
T. Mikoviny ◽  
S. Feil ◽  
S. Haidacher ◽  
G. Hanel ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Proton Transfer Reaction ◽  
Horizontal Resolution ◽  
Resolving Power ◽  
Spatiotemporal Resolution ◽  
Airborne Measurements ◽  
New Instrument ◽  
Volatile Organic ◽  
Tof Ms

Abstract. Herein, we report on the development of a compact proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) for airborne measurements of volatile organic compounds (VOCs). The new instrument resolves isobaric ions with a mass resolving power (m/Δm) of ~1000, provides accurate m/z measurements (Δm < 3 mDa), records full mass spectra at 1 Hz and thus overcomes some of the major analytical deficiencies of quadrupole-MS-based airborne instruments. 1 Hz detection limits for biogenic VOCs (isoprene, α total monoterpenes), aromatic VOCs (benzene, toluene, xylenes) and ketones (acetone, methyl ethyl ketone) range from 0.05 to 0.12 ppbV, making the instrument well-suited for fast measurements of abundant VOCs in the continental boundary layer. The instrument detects and quantifies VOCs in locally confined plumes (< 1 km), which improves our capability of characterizing emission sources and atmospheric processing within plumes. A deployment during the NASA 2013 DISCOVER-AQ mission generated high vertical- and horizontal-resolution in situ data of VOCs and ammonia for the validation of satellite retrievals and chemistry transport models.

scholarly journals Canopy-scale flux measurements and bottom-up emission estimates of volatile organic compounds from a mixed oak and hornbeam forest in northern Italy

2016 ◽  
Vol 16 (11) ◽  
pp. 7149-7170 ◽  
Author(s):  
W. Joe F. Acton ◽  
Simon Schallhart ◽  
Ben Langford ◽  
Amy Valach ◽  
Pekka Rantala ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Northern Italy ◽  
Top Down ◽  
Bottom Up ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
Leaf Level ◽  
Tof Ms

Abstract. This paper reports the fluxes and mixing ratios of biogenically emitted volatile organic compounds (BVOCs) 4 m above a mixed oak and hornbeam forest in northern Italy. Fluxes of methanol, acetaldehyde, isoprene, methyl vinyl ketone + methacrolein, methyl ethyl ketone and monoterpenes were obtained using both a proton-transfer-reaction mass spectrometer (PTR-MS) and a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) together with the methods of virtual disjunct eddy covariance (using PTR-MS) and eddy covariance (using PTR-ToF-MS). Isoprene was the dominant emitted compound with a mean daytime flux of 1.9 mg m−2 h−1. Mixing ratios, recorded 4 m above the canopy, were dominated by methanol with a mean value of 6.2 ppbv over the 28-day measurement period. Comparison of isoprene fluxes calculated using the PTR-MS and PTR-ToF-MS showed very good agreement while comparison of the monoterpene fluxes suggested a slight over estimation of the flux by the PTR-MS. A basal isoprene emission rate for the forest of 1.7 mg m−2 h−1 was calculated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN) isoprene emission algorithms (Guenther et al., 2006). A detailed tree-species distribution map for the site enabled the leaf-level emission of isoprene and monoterpenes recorded using gas-chromatography mass spectrometry (GC–MS) to be scaled up to produce a bottom-up canopy-scale flux. This was compared with the top-down canopy-scale flux obtained by measurements. For monoterpenes, the two estimates were closely correlated and this correlation improved when the plant-species composition in the individual flux footprint was taken into account. However, the bottom-up approach significantly underestimated the isoprene flux, compared with the top-down measurements, suggesting that the leaf-level measurements were not representative of actual emission rates.

scholarly journals Fluxes and concentrations of volatile organic compounds above central London, UK

2010 ◽  
Vol 10 (2) ◽  
pp. 627-645 ◽  
Author(s):  
B. Langford ◽  
E. Nemitz ◽  
E. House ◽  
G. J. Phillips ◽  
D. Famulari ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Traffic Density ◽  
Mixing Ratios ◽  
Oxygenated Compounds ◽  
Volatile Organic ◽  
Benzene Toluene ◽  
The Uk

Abstract. Concentrations and fluxes of eight volatile organic compounds (VOCs) were measured during October 2006 from a high telecom tower above central London, as part of the CityFlux contribution to the REPARTEE I campaign. A continuous flow disjunct eddy covariance technique with analysis by proton transfer reaction mass spectrometry was used. Daily averaged VOC mixing ratios were within the range 1–19 ppb for the oxygenated compounds (methanol, acetaldehyde and acetone) and 0.2–1.3 ppb for the aromatics (benzene, toluene and C2-benzenes). Typical VOC fluxes were in the range 0.1–1.0 mg m−2 h−1. There was a non-linear relationship between VOC fluxes and traffic density for most of the measured compounds. Traffic activity was estimated to account for approximately 70% of the aromatic compound fluxes, whereas non-traffic related sources were found to be more important for methanol and isoprene fluxes. The measured fluxes were comparable to the estimates of the UK national atmospheric emission inventory for the aromatic VOCs and CO. In contrast, fluxes of the oxygenated compounds were about three times larger than inventory estimates. For isoprene and acetonitrile this difference was many times larger. At temperatures over 25° C it is estimated that more than half the isoprene observed in central London is of biogenic origin.

scholarly journals Canopy-scale flux measurements and bottom-up emission estimates of volatile organic compounds from a mixed oak and hornbeam forest in northern Italy

2015 ◽  
Vol 15 (20) ◽  
pp. 29213-29264 ◽  
Author(s):  
W. J. F. Acton ◽  
S. Schallhart ◽  
B. Langford ◽  
A. Valach ◽  
P. Rantala ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Northern Italy ◽  
Top Down ◽  
Bottom Up ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
Leaf Level ◽  
Tof Ms

Abstract. This paper reports the fluxes and mixing ratios of biogenically emitted volatile organic compounds (BVOCs) 4 m above a mixed oak and hornbeam forest in northern Italy. Fluxes of methanol, acetaldehyde, isoprene, methyl vinyl ketone + methacrolein, methyl ethyl ketone and monoterpenes were obtained using both a proton transfer reaction-mass spectrometer (PTR-MS) and a proton transfer reaction-time of flight-mass spectrometer (PTR-ToF-MS) together with the methods of virtual disjunct eddy covariance (PTR-MS) and eddy covariance (PTR-ToF-MS). Isoprene was the dominant emitted compound with a mean day-time flux of 1.9 mg m-2 h-1. Mixing ratios, recorded 4 m above the canopy, were dominated by methanol with a mean value of 6.2 ppbv over the 28 day measurement period. Comparison of isoprene fluxes calculated using the PTR-MS and PTR-ToF-MS showed very good agreement while comparison of the monoterpene fluxes suggested a slight over estimation of the flux by the PTR-MS. A basal isoprene emission rate for the forest of 1.7 mg m-2 h-1 was calculated using the MEGAN isoprene emissions algorithms (Guenther et al., 2006). A detailed tree species distribution map for the site enabled the leaf-level emissions of isoprene and monoterpenes recorded using GC-MS to be scaled up to produce a "bottom-up" canopy-scale flux. This was compared with the "top-down" canopy-scale flux obtained by measurements. For monoterpenes, the two estimates were closely correlated and this correlation improved when the plant species composition in the individual flux footprint was taken into account. However, the bottom-up approach significantly underestimated the isoprene flux, compared with the top-down measurements, suggesting that the leaf-level measurements were not representative of actual emission rates.

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