Oxygenated Aromatic Compounds are Important Precursors of Secondary Organic Aerosol in Biomass-Burning Emissions

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 54(14), P. 8568 - 8579

Published: June 19, 2020

Biomass burning is the largest combustion-related source of volatile organic compounds (VOCs) to atmosphere. We describe development a state-of-the-science model simulate photochemical formation secondary aerosol (SOA) from biomass-burning emissions observed in dry (RH <20%) environmental chamber experiments. The modeling supported by (i) new oxidation measurements, (ii) detailed concurrent measurements SOA precursors emissions, and (iii) parameters for heterocyclic oxygenated aromatic based on historical find that compounds, including phenols methoxyphenols, account slightly less than 60% formed help our explain variability mass (R2 = 0.68) O/C 0.69) enhancement ratios across 11 Despite abundant included furans contribute ∼20% total SOA. use pyrolysis-temperature-based or averaged emission profiles represent precursors, rather those specific each fire, provide similar results within 20%. Our findings demonstrate necessity accounting aromatics their chemical mechanisms.

Language: Английский

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Ozone chemistry in western U.S. wildfire plumes

Science Advances, Journal Year: 2021, Volume and Issue: 7(50)

Published: Dec. 8, 2021

Wildfires are a substantial but poorly quantified source of tropospheric ozone (O3). Here, to investigate the highly variable O3 chemistry in wildfire plumes, we exploit situ chemical characterization western wildfires during FIREX-AQ flight campaign and show that production can be predicted as function experimentally constrained OH exposure, volatile organic compound (VOC) reactivity, fate peroxy radicals. The exhibits rapid transition regimes. Within few daylight hours, formation substantially slows is largely limited by abundance nitrogen oxides (NOx). This finding supports previous observations enhanced when VOC-rich smoke mixes into NOx-rich urban thereby deteriorating air quality. Last, relate underlying fire characteristics, enabling more accurate representation atmospheric models used study quality predict climate.

Language: Английский

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Large contribution of biomass burning emissions to ozone throughout the global remote troposphere

Proceedings of the National Academy of Sciences, Journal Year: 2021, Volume and Issue: 118(52)

Published: Dec. 20, 2021

Significance Understanding the sources of tropospheric ozone is important for effective air quality management and accurate radiative forcing attribution. Biomass burning emits large quantities precursors to lower atmosphere. This source can drive regional-scale production, but its impact on global poorly constrained. Here, we present unique in situ aircraft observations continental pollution tracers. Ozone enhancements attributable biomass equal or exceed those from urban emissions, a result that not predicted by current chemical transport models. These findings represent potentially major shift understanding atmosphere indicate need model developments improve representation ozone.

Language: Английский

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Measurement report: Important contributions of oxygenated compounds to emissions and chemistry of volatile organic compounds in urban air

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(23), P. 14769 - 14785

Published: Dec. 2, 2020

Abstract. Volatile organic compounds (VOCs) play important roles in the tropospheric atmosphere. In this study, VOCs were measured at an urban site Guangzhou, one of megacities Pearl River Delta (PRD), using a gas chromatograph–mass spectrometer/flame ionization detection (GC–MS/FID) and proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). Diurnal profile analyses show that stronger chemical removal by OH radicals for more reactive hydrocarbons occurs during daytime, which is used to estimate daytime average radical concentration. comparison, diurnal profiles oxygenated volatile (OVOCs) indicate evidence contributions from secondary formation. Detailed source OVOCs, photochemical age-based parameterization method, suggest both primary emissions formation OVOCs. During campaign, around 1700 ions detected PTR-ToF-MS spectra, among there 462 with noticeable concentrations. VOC signals these are quantified based on sensitivities available species. OVOC-related dominated contribution 73 % ± 9 %. Combining measurements GC–MS/FID, OVOCs contribute 57 10 total concentration VOCs. Using concurrent reactivity, greatly reactivity (19 %). account 21 11 reactivity. Adding up inorganic gases (48 15 %), ∼ (range 0 %–19 %) remains `missing”, well within combined uncertainties between calculated Our results demonstrate emission evolution budget

Language: Английский

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Emissions of Trace Organic Gases From Western U.S. Wildfires Based on WE‐CAN Aircraft Measurements

Journal of Geophysical Research Atmospheres, Journal Year: 2021, Volume and Issue: 126(11)

Published: May 9, 2021

Abstract We present emission measurements of volatile organic compounds (VOCs) for western U.S. wildland fires made on the NSF/NCAR C‐130 research aircraft during Western Wildfire Experiment Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) field campaign in summer 2018. VOCs were measured with complementary instruments onboard C‐130, including a proton‐transfer‐reaction time‐of‐flight mass spectrometer (PTR‐ToF‐MS) two gas chromatography (GC)‐based methods. Agreement within combined instrument uncertainties (<60%) was observed most co‐measured VOCs. GC‐based speciated isomeric contributions to selected PTR‐ToF‐MS ion masses generally showed little fire‐to‐fire variation. report ratios (ERs) factors (EFs) 161 31 near‐fire smoke plume transects 24 specific individual sampled afternoon when burning conditions are typically active. Modified combustion efficiency (MCE) ranged from 0.85 0.94. The campaign‐average total VOC EF 26.1 ± 6.9 g kg −1 , approximately 67% which is accounted by oxygenated 10 abundantly emitted species contributed more than half mass. found that MCE alone explained nearly 70% variance emissions ( r 2 = 0.67) >50% 57 EFs representing carbon Finally, we variability fraction emissions, suggesting single speciation profile can describe wildfires coniferous ecosystems WE‐CAN.

Language: Английский

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Fire Influence on Regional to Global Environments and Air Quality (FIREX‐AQ)

Journal of Geophysical Research Atmospheres, Journal Year: 2022, Volume and Issue: 128(2)

Published: Dec. 30, 2022

Abstract The NOAA/NASA Fire Influence on Regional to Global Environments and Air Quality (FIREX‐AQ) experiment was a multi‐agency, inter‐disciplinary research effort to: (a) obtain detailed measurements of trace gas aerosol emissions from wildfires prescribed fires using aircraft, satellites ground‐based instruments, (b) make extensive suborbital remote sensing fire dynamics, (c) assess local, regional, global modeling fires, (d) strengthen connections observables the ground such as fuels fuel consumption satellite products burned area radiative power. From Boise, ID western were studied with NASA DC‐8 two NOAA Twin Otter aircraft. high‐altitude ER‐2 deployed Palmdale, CA observe some these in conjunction overpasses other Further conducted three mobile laboratories sites, 17 different forecast analyses for fire, air quality climate implications. Salina, KS investigated 87 smaller Southeast in‐situ data collection. Sampling by all platforms designed measure gases aerosols multiple transects capture chemical transformation perform observations smoke plumes under day night conditions. linked consumed power orbital collected during overflights sampling fuels.

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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New Insights into the Radical Chemistry and Product Distribution in the OH-Initiated Oxidation of Benzene

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 54(21), P. 13467 - 13477

Published: Oct. 21, 2020

Emissions of aromatic compounds cause air pollution and detrimental health effects. Here, we explore the reaction kinetics products key radicals in benzene photo-oxidation. After initial OH addition with O2, effective production rates phenol bicyclic peroxy radical (BCP-peroxy) are experimentally constrained at 295 K to be 420 ± 80 370 70 s–1, respectively. These lead approximately 53% yield for 47% BCP-peroxy under atmospheric conditions. The NO produces hydroxy nitrate a branching ratio <0.2%, indicating efficient NOx recycling. Similarly, HO2 largely recycles HOx, producing corresponding alkoxy (BCP-oxy). Because presence C–C double bonds multiple functional groups, chemistry BCP-oxy other system is diverse. Experimental results suggest aldehydic H-shift ring-closure produce an epoxide functionality could competitive classic decomposition radicals. reactions potential sources highly oxygenated molecules. Finally, despite large number observed our study, unable account ∼20% carbon flow.

Language: Английский

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Secondary organic aerosol formation from the laboratory oxidation of biomass burning emissions

Atmospheric chemistry and physics, Journal Year: 2019, Volume and Issue: 19(19), P. 12797 - 12809

Published: Oct. 14, 2019

Abstract. Biomass burning is an important source of aerosol and trace gases to the atmosphere, but how these emissions change chemically during their lifetimes not fully understood. As part Fire Influence on Regional Global Environments Experiment (FIREX 2016), we investigated effect photochemical aging biomass organic (BBOA) with a focus fuels from western United States. Emissions were sampled into small (150 L) environmental chamber photochemically aged via addition ozone irradiation by 254 nm light. While some fraction species undergoes photolysis, vast majority occurs reaction OH radicals, total exposures corresponding equivalent up 10 d atmospheric oxidation. For all burned, large rapid changes are seen in ensemble chemical composition BBOA, as measured mass spectrometer (AMS). Secondary (SOA) formation for experiments continues grow increasing exposure, magnitude SOA highly variable between experiments. This variability can be explained well combination differences exposure concentration non-methane (NMOGs) before oxidation, PTR-ToF-MS (r2 values 0.64 0.83). From this relationship, calculate carbon NMOGs that converted function time, yields ranging 24±4 % after 6 h 56±9 4 d.

Language: Английский

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Biomass-burning-derived particles from a wide variety of fuels – Part 1: Properties of primary particles

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(3), P. 1531 - 1547

Published: Feb. 7, 2020

Abstract. Relationships between various optical, physical, and chemical properties of biomass-combustion-derived particles are characterized for produced in the laboratory from a wide range fuels burn conditions. The modified combustion efficiency (MCE), commonly used to parameterize biomass particle emissions properties, is shown generally have weak predictive capabilities, especially more efficient There is, however, strong relationship many intensive optical (e.g., single-scatter albedo, Ångström absorption exponent, mass efficiency) organic aerosol-to-black carbon ([OA] ∕ [BC]) ratio over wider than previously considered (0.3 105). brown (BrC, i.e., light-absorbing carbon) also vary with [OA] [BC]. Coating-induced enhancements (i.e., “lensing” effects) contribute only minor amount BC all burns despite some producing having large ensemble-average coating-to-core ratios. BC–OA mixing state varies strongly [BC]; fraction OA that internally mixed decreases [BC] while relative coated on increases. In contrast, there little bulk [BC], O : C H atomic ratios abundance key marker ion (m/z=60, linked levoglucosan) showing no dependence both nitrate volatility do depend Neither total nor BC-specific size distributions exhibit any clear conditions or although perhaps fuel type. Overall, our results expand existing knowledge new understanding emitted combustion.

Language: Английский

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