Identifying and correcting interferences to PTR-ToF-MS measurements of isoprene and other urban volatile organic compounds

Atmospheric measurement techniques, Journal Year: 2024, Volume and Issue: 17(2), P. 801 - 825

Published: Jan. 31, 2024

Abstract. Proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) is a technique commonly used to measure ambient volatile organic compounds (VOCs) in urban, rural, and remote environments. PTR-ToF-MS known produce artifacts from ion fragmentation, which complicates the interpretation quantification of key atmospheric VOCs. This study evaluates extent fragmentation other ionization processes impact urban measurements ions typically assigned isoprene (m/z 69, C5H8H+), acetaldehyde 45, CH3CHO+), benzene 79, C6H6H+). Interferences are identified using gas chromatography (GC) pre-separation, these interferences quantified ground-based airborne number US cities, including Las Vegas, Los Angeles, New York City, Detroit. In regions with low biogenic emissions (e.g., Vegas), higher-carbon aldehydes cycloalkanes emitted anthropogenic sources may contribute m/z 69 by as much 50 % during day, while majority signal at attributed night. higher fraction studies, likely results differences reactivity between interfering species along subsequent changes VOC mixture altitudes. For PTR masses, 45 observed due O2+ VOCs solvents, becoming more important source areas. We present methods correct interferences, provide better agreement GC isomer-specific molecules. These observations show utility deploying pre-separation for spectra.

Language: Английский

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Parameterizations of US wildfire and prescribed fire emission ratios and emission factors based on FIREX-AQ aircraft measurements

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(2), P. 929 - 956

Published: Jan. 23, 2024

Abstract. Extensive airborne measurements of non-methane organic gases (NMOGs), methane, nitrogen oxides, reduced species, and aerosol emissions from US wild prescribed fires were conducted during the 2019 NOAA/NASA Fire Influence on Regional to Global Environments Air Quality campaign (FIREX-AQ). Here, we report atmospheric enhancement ratios (ERs) inferred emission factors (EFs) for compounds measured board NASA DC-8 research aircraft nine wildfires one fire, which encompass a range vegetation types. We use photochemical proxies identify young smoke reduce effects chemical degradation our calculations. ERs EFs calculated FIREX-AQ observations agree within factor 2, with values reported previous laboratory field studies more than 80 % carbon- nitrogen-containing species. Wildfire are parameterized based correlations sum NMOGs reactive oxides (NOy) modified combustion efficiency (MCE) as well other signatures indicative flaming/smoldering combustion, including carbon monoxide (CO), dioxide (NO2), black aerosol. The primary NMOG correlates MCE an R2 0.68 slope −296 ± 51 g kg−1, consistent studies. mixing CO 0.98 137 4 ppbv per parts million by volume (ppmv) CO, demonstrating that can be estimated CO. Individual species correlate better NO2, NOy, More half NOy in fresh plumes is NO2 0.95 ratio 0.55 0.05 ppbv−1, highlighting fast photochemistry had already occurred sampled fire plumes. follows trends observed experiments increases exponentially MCE, due increased key at higher flaming combustion. These parameterizations will provide accurate boundary conditions modeling satellite plume chemistry evolution predict downwind formation secondary pollutants, ozone

Language: Английский

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Identifying and correcting interferences to PTR-ToF-MS measurements of isoprene and other urban volatile organic compounds

Published: Aug. 28, 2023

Abstract. Proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) is a technique commonly used to measure ambient volatile organic compounds (VOCs) in urban, rural, and remote environments. PTR-ToF-MS known produce artifacts from ion fragmentation, which complicates the interpretation quantification of key atmospheric VOCs. This study evaluates extent fragmentation other ionization processes impacts urban measurements ions typically assigned isoprene (m/z 69, C5H8H+), acetaldehyde 45, CH3CHO+), benzene 79, C6H6H+). Interferences are identified using gas-chromatography (GC) pre-separation impact these interferences quantified ground-based airborne number US cities, including Las Vegas, Los Angeles, New York City, Detroit. In regions with low biogenic emissions (e.g., Vegas), higher carbon aldehydes cycloalkanes emitted anthropogenic sources may contribute m/z 69 by as much 50 % during day, while majority signal at attributed night. fraction studies, likely results differences reactivity between interfering species along subsequent changes VOC mixture altitudes. For PTR masses, 45 observed due secondary VOCs solvents, becoming more important source areas. We present methods correct interferences, provide better agreement GC isomer specific molecules. These observations show utility deploying for spectra.

Language: Английский

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Measurement report: Characteristics of nitrogen-containing organics in PM_2.5 in Ürümqi, northwestern China – differential impacts of combustion of fresh and aged biomass materials

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(7), P. 4331 - 4346

Published: April 15, 2024

Abstract. Nitrogen-containing organic compounds (NOCs) are abundant and important aerosol components deeply involved in the global nitrogen cycle. However, sources formation processes of NOCs remain largely unknown, particularly city (Ürümqi, China) farthest from ocean worldwide. Here, PM2.5 collected Ürümqi over a 1-year period were characterized by ultra-high-resolution mass spectrometry. The abundance CHON (mainly oxygen-poor unsaturated aliphatic-like species) positive ion mode was higher warm than cold period, which attributed to contribution fresh biomass material combustion (e.g., forest fires) associated with amidation fatty acids rather oxidation processes. nitro-aromatic negative increased significantly tightly related aged dry straws) wintertime Ürümqi. For CHN compounds, alkyl nitriles aromatic species showed periods, respectively. Alkyl can be derived dehydration amides (the main period). In contrast, burning. These findings further suggested different impacts materials on NOC compositions seasons. overall results shed light mechanisms release during combustion.

Language: Английский

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Impact of improved representation of volatile organic compound emissions and production of NO_x reservoirs on modeled urban ozone production

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(16), P. 9555 - 9572

Published: Aug. 29, 2024

Abstract. The fraction of urban volatile organic compound (VOC) emissions attributable to fossil fuel combustion has been declining in many parts the world, resulting a need better constrain other anthropogenic sources these emissions. During National Institute Environmental Research (NIER) and Aeronautics Space Administration (NASA) Korea-United States Air Quality (KORUS-AQ) field study Seoul, South Korea, during May–June 2016, air quality models underestimated ozone, formaldehyde, peroxyacetyl nitrate (PAN), indicating an underestimate VOCs inventory. Here, we use aircraft observations interpreted with GEOS-Chem chemical transport model (version 13.4.0) assess for increases VOC revised mechanism improve treatment speciation chemistry. We find that largest needed are compounds associated products, liquefied petroleum gas (LPG) natural emissions, long-range transport. Revising chemistry match observed together increasing species increased calculated OH reactivity by +2 s−1 ozone production ppb h−1. Ozone +6 below 2 km +9 at surface, formaldehyde acetaldehyde +30 % +120 aloft, respectively, all agreement observations. larger increase was attributed ethanol which found be as important isoprene or alkenes. significantly reduced PAN bias. additional unmeasured VOCs, however, indicated remaining bias −0.8 −57 −52 higher peroxynitrates (PNs) alkyl nitrates (ANs), respectively. added represent six PNs from but were unable account majority missing PNs. However, four modeled concentrations similar commonly measured (> PAN) should future campaigns considered emission (e.g., fires). hypothesize oxygenated (OVOCs) such ≥ C5 aldehydes cooking and/or alkenes products could produce both ANs biases. Emerging research on will soon allow modeling their impact local regional photochemistry.

Language: Английский

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Emission Factors for Crop Residue and Prescribed Fires in the Eastern US During FIREX‐AQ

Journal of Geophysical Research Atmospheres, Journal Year: 2023, Volume and Issue: 128(18)

Published: Sept. 2, 2023

Abstract Agricultural and prescribed burning activities emit large amounts of trace gases aerosols on regional to global scales. We present a compilation emission factors (EFs) ratios from the eastern portion Fire Influence Regional Global Environments Air Quality (FIREX‐AQ) campaign in 2019 United States, which sampled crop residues other fire fuels. FIREX‐AQ provided comprehensive chemical characterization 53 residue 22 fires. Crop burned at different modified combustion efficiencies (MCE), with corn higher MCE than fuel types. Prescribed fires lower (<0.90) is typical, while grasslands (0.90) normally observed due moist, green, growing season Most non‐methane volatile organic compounds (NMVOCs) were significantly anticorrelated except for ethanol NMVOCs that measured less certainty. identified 23 species where differed by more 50% same MCE. EFs greater related agricultural use composition as well oxygenated possibly presence metals such potassium. monoterpenes (5×). average generally agreed previous study US but had disagreements compilations. observations show importance regionally‐specific fuel‐specific first steps reduce uncertainty modeling air quality impacts emissions.

Language: Английский

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Atmospheric reduced nitrogen: Sources, transformations, effects, and management

Journal of the Air & Waste Management Association, Journal Year: 2024, Volume and Issue: 74(6), P. 362 - 415

Published: May 31, 2024

Human activities have increased atmospheric emissions and deposition of oxidized reduced forms nitrogen, but emission control programs largely focused on nitrogen. As a result, in many regions the world nitrogen are decreasing while increasing. Emissions originate from livestock waste fertilizer application, with contributions transportation sources urban areas. Observations suggest discrepancy between trends U.S., likely due to an underestimate emissions. In atmosphere, ammonia reacts oxides sulfur form fine particulate matter that impairs health visibility affects climate forcings. Recent reductions limited partitioning ammonia, long-range transport. Continuing research is needed improve understanding how shifting alter formation secondary particulates patterns transport reactive Satellite remote sensing has potential for monitoring concentrations there remains need maintain strengthen ground-based measurements continue development chemical models. Elevated decreased plant soil microbial biodiversity altered biogeochemical function terrestrial, freshwater, coastal ecosystems. Further study differential effects versus pathways timescales ecosystem recovery elevated deposition. Decreases could alleviate exceedances critical loads terrestrial freshwater indicators U.S. The Environmental Protection Agency should consider using as basis setting standards protect public welfare other countries might look European experience approaches agricultural sectors.

Language: Английский

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Atmospheric deposition of chromophoric dissolved organic matter in the Athabasca Oil Sands Region, Canada, is strongly influenced by industrial sources during the winter months

Environmental Pollution, Journal Year: 2025, Volume and Issue: 371, P. 125936 - 125936

Published: Feb. 26, 2025

Language: Английский

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The Impact of the 2023 Canadian Forest Fires on Air Quality in Southern Ontario

Journal of Geophysical Research Atmospheres, Journal Year: 2025, Volume and Issue: 130(5)

Published: March 3, 2025

Abstract The record‐breaking 2023 Canadian wildfire season had large‐scale burning that resulted in wide‐reaching long‐range transport of smoke plumes and their associated trace gases. This paper examines three events (May 16‐23, June 3‐9 17‐30, 2023) during which the composition was measured over Toronto Egbert, Ontario. Tropospheric columns (0–10 km) CO, C 2 H 6 , CH 3 OH, HCN, HCOOH, NH O were using high‐resolution Fourier transform infrared spectrometers. Coincident enhancements CO other gases used to calculate enhancement ratios. Correlations with observed for HCN but not . Plume investigated Hybrid Single‐Particle Lagrangian Integrated Trajectory model, GEM‐MACH‐FireWork (GM‐FW) air quality Measurements Pollution Troposphere (MOPITT) satellite data. Additional measurements examined surface PM 2.5 plume height from a Mini Micro Pulse Lidar, EM27/SUN XCO columns. GM‐FW model output compared ground‐based 0–10 km column measurements, MOPITT maps. Over forest fire (May‐September), underestimated background tropospheric generally overestimated events. Relative situ seasonal averages (which enhanced events), while fluctuated between positive negative bias. Compared MOPITT, event‐averaged appropriately represent dispersion across country, some offsets on scale locations are consistent discussed findings.

Language: Английский

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Ammonia in the upper troposphere–lower stratosphere (UTLS): GLORIA airborne measurements for CAMS model evaluation in the Asian monsoon and in biomass burning plumes above the South Atlantic

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(14), P. 8125 - 8138

Published: July 19, 2024

Abstract. Ammonia (NH3) is the major alkaline species in atmosphere and plays an important role aerosol formation, which affects local air quality radiation budget. NH3 upper troposphere lower stratosphere (UTLS) difficult to detect, only limited observations are available. We present two-dimensional trace gas measurements of obtained by airborne infrared imaging limb sounder GLORIA (Gimballed Limb Observer for Radiance Imaging Atmosphere) that was operated on board research aircraft Geophysica within Asian monsoon anticyclone during StratoClim campaign (July 2017) HALO (the High Altitude LOng Range aircraft) above South Atlantic SouthTRAC (September–November 2019). compare these UTLS with results CAMS (Copernicus Atmosphere Monitoring Service) reanalysis forecast model evaluate its performance. The reveal large enhancements more than 1 ppbv but no clear indication biomass burning plumes instrument's detection limit around 20 pptv. In contrast, simulation indicate strong both measured scenarios. Comparisons other retrieved pollution gases, such as peroxyacetyl nitrate (PAN), show ability models generally reproduce Atlantic. However, concentrations largely overestimated plumes. suggest emission strengths used accuracy comparison agricultural sources monsoon. Further, we loss processes transport may be underestimated cases Since strongly undersampled, particular at higher altitudes, hope regular vertically resolved from proposed CAIRT (Changing-Atmosphere Infra-Red Tomography Explorer) mission strengthen our understanding this atmosphere.

Language: Английский

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