Aging of Atmospheric Brown Carbon Aerosol

ACS Earth and Space Chemistry, Journal Year: 2021, Volume and Issue: 5(4), P. 722 - 748

Published: April 5, 2021

Emitted by numerous primary sources and formed secondary sources, atmospheric brown carbon (BrC) aerosol is chemically complex. As BrC ages in the atmosphere via a variety of chemical physical processes, its composition optical properties change significantly, altering impacts on climate. Research past decade has considerably expanded our understanding reactions both gas condensed phases. We review these recent advances aging chemistry with focus phase leading to formation, aqueous in-cloud particle reactions. Connections are made between single component proxies more complex mixtures as well laboratory field measurements chemistry. General conclusions that can darken particles over short time scales hours close source considerable photobleaching oxidative whitening will occur when day or removed from source.

Language: Английский

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Global Measurements of Brown Carbon and Estimated Direct Radiative Effects

Geophysical Research Letters, Journal Year: 2020, Volume and Issue: 47(13)

Published: June 16, 2020

Abstract Brown carbon (BrC) is an organic aerosol material that preferentially absorbs light of shorter wavelengths. Global‐scale radiative impacts BrC have been difficult to assess due the lack observational data. To address this, filters were continuously collected with near pole‐to‐pole latitudinal coverage over Pacific and Atlantic basins in three seasons as part Atmospheric Tomography Mission. chromophores filter extracts measured. We find globally, was highly spatially heterogeneous, mostly detected air masses had transported from regions extensive biomass burning. calculate average direct effect absorption accounted for approximately 7% 48% top atmosphere clear‐sky instantaneous forcing by all absorbing carbonaceous aerosols remote atmosphere, indicating burning important component global balance.

Language: Английский

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Brown carbon from biomass burning imposes strong circum-Arctic warming

One Earth, Journal Year: 2022, Volume and Issue: 5(3), P. 293 - 304

Published: March 1, 2022

Rapid warming in the Arctic has a huge impact on global environment. Atmospheric brown carbon (BrC) is one of least understood and uncertain agents due to scarcity observations. Here, we performed direct observations atmospheric BrC quantified its light-absorbing properties during 2-month circum-Arctic cruise summer 2017. Through observation-constrained modeling, show that BrC, mainly originated from biomass burning mid- high latitudes Northern Hemisphere (∼60%), can be strong agent region, especially summer, with an average radiative forcing ∼90 mW m−2 (∼30% relative black carbon). As climate change projected increase frequency, intensity, spread wildfires, expect play increasing role future.

Language: Английский

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Molecular Analysis of Secondary Brown Carbon Produced from the Photooxidation of Naphthalene

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(6), P. 3340 - 3353

Published: March 1, 2022

We investigate the chemical composition of organic light-absorbing components, also known as brown carbon (BrC) chromophores, formed in a proxy anthropogenic secondary aerosol generated from photooxidation naphthalene (naph-SOA) absence and presence NOx. High-performance liquid chromatography equipped with photodiode array detector electrospray ionization high-resolution mass spectrometer is employed to characterize naph-SOA its BrC components. provide molecular-level insights into optical properties individual components their relevance. This work reveals formation strongly absorbing nitro-aromatic chromophores under high-NOx conditions describes degradation during atmospheric aging. NOx addition enhanced light absorption while reducing wavelength-dependence, seen by coefficient (MAC) Ångström exponent (AAE). Optical parameters low- showed range values MACOM 405nm ∼ 0.12 m2 g–1 AAE300–450nm 8.87 (low-NOx) 0.19 7.59 (high-NOx), consistent "very weak" "weak" classes, respectively. The weak-BrC class commonly attributed biomass smoldering emissions, which appear have comparable naph-SOA. Molecular contributing were identified substantial nitro-aromatics, indicating that these species may be used source-specific markers related emissions.

Language: Английский

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Nitrogen-Containing Compounds Enhance Light Absorption of Aromatic-Derived Brown Carbon

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(7), P. 4005 - 4016

Published: Feb. 22, 2022

The formation of secondary brown carbon (BrC) is chemically complex, leading to an unclear relationship between its molecular composition and optical properties. Here, we present in-depth investigation molecular-specific properties aging BrC produced from the photooxidation ethylbenzene at varied NOx levels for first time. Due pronounced unsaturated products, mass absorption coefficient (MAC) organic aerosols (ESOA) 365 nm was higher than that biogenic SOA by a factor 10. A high level ([ethylbenzene]0/[NOx]0 < 10 ppbC ppb–1) found significantly increase average MAC300–700nm ESOA 0.29 m2 g–1. data two complementary high-resolution spectrometers quantum chemical calculations suggested nitrogen-containing compounds were largely responsible enhanced light high-NOx ESOA, multifunctional nitroaromatic (such as C8H9NO3 C8H9NO4) identified important chromophores. High-NOx underwent photobleaching upon direct exposure ultraviolet light. Photolysis did not lead significant decomposition C8H9NO4, indicating may serve relatively stable nitrogen reservoirs would effectively absorb solar radiation during daytime.

Language: Английский

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pH-Dependent Aqueous-Phase Brown Carbon Formation: Rate Constants and Implications for Solar Absorption and Atmospheric Photochemistry

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(2), P. 1236 - 1243

Published: Jan. 3, 2024

Aqueous-phase reactions of α-dicarbonyls with amines or ammonium have been identified as important sources secondary brown carbon (BrC). However, the kinetics BrC formation and effects pH are still not very clear. In this study, by aqueous (glyoxal methylglyoxal) ammonium, amino acids, alkylamines in bulk solution at different values investigated. Our results reveal pH-parameterized production rate constants, kBrCII (m–1 [M]−2 s–1), based on light absorption between 300 500 nm: log10(kBrCII) = (1.0 ± 0.1) × – (7.4 1.0) for glyoxal (6.3 0.9) methylglyoxal. The linear slopes closing to 1.0 indicate that is governed nitrogen nucleophilic addition pathway. Consequently, absorptivities produced increase exponentially pH. from methylglyoxal higher (≥6.5) exhibits optical properties comparable biomass burning coal combustion, categorized "weakly" absorbing BrC, while lower (<6.0) (pH 5.0–7.0) falls into "very weakly" BrC. pH-dependent feature significantly affects solar ability thus atmospheric photochemical processes, e.g., 7.0 absorbs 14–16 times more power compared 5.0, which turn could lead a decrease 1 order magnitude photolysis constants O3 NO2.

Language: Английский

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Characteristics and evolution of brown carbon in western United States wildfires

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(12), P. 8009 - 8036

Published: June 21, 2022

Abstract. Brown carbon (BrC) associated with aerosol particles in western United States wildfires was measured between July and August 2019 aboard the NASA DC-8 research aircraft during Fire Influence on Regional to Global Environments Air Quality (FIREX-AQ) study. Two BrC measurement methods are investigated, highly spectrally resolved light absorption solvent (water methanol) extracts of collected filters situ bulk particle at three wavelengths (405, 532 664 nm) a photoacoustic spectrometer (PAS). A light-absorption closure analysis for 300 700 nm performed. The combined pure black material, including enhancements due internally mixed materials, plus soluble Mie-predicted factor conversion BrC, compared spectra from power law fit PAS wavelengths. For various parameters used, wavelength roughly 400 they agreed, lower individual component-predicted significantly exceeded higher consistently but more variable. Limitations extrapolation data below 405 missing species low solubility that strongly absorb may account differences. Based measurements closest fires, emission ratio PAS-measured relative monoxide (CO) average 0.13 Mm−1 ppbv−1; ratios also provided. As smoke moved away burning regions, evolution over time observed be complex; enhancement, depletion or constant levels age were all first 8 h after different plumes. Within following emissions, 4-nitrocatechol, well-characterized chromophore commonly found particles, largely depleted BrC. In descending plume where temperature increased by 15 K, 4-nitrocatechol dropped, possibly temperature-driven evaporation, remained unchanged. Evidence reactions ozone, related species, as pathway secondary formation under both high oxides nitrogen (NOx) conditions, while bleached regions ozone NOx, consistent complex behaviors laboratory studies. Although hours is variable, limited number aged (15 30 h) indicate net loss It yet determined how near-field affects characteristics longer timescales spatial scales, its environmental impacts likely greater.

Language: Английский

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New Insights into the Brown Carbon Chromophores and Formation Pathways for Aqueous Reactions of α-Dicarbonyls with Amines and Ammonium

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(33), P. 12351 - 12361

Published: Aug. 5, 2023

Aqueous-phase reactions of α-dicarbonyls with ammonium or amines have been identified as important sources secondary brown carbon (BrC). However, the identities most chromophores in these and effects pH remain largely unknown. In this study, chemical structures, formation pathways, optical properties individual BrC formed through aqueous (glyoxal methylglyoxal) ammonium, amino acids, methylamine at different pH's were characterized detail by liquid chromatography-photodiode array-high resolution tandem mass spectrometry. total, 180 are identified, accounting for 29-79% light absorption bulk reactions. Thereinto, 155 newly chromophores, including 76 imidazoles, 57 pyrroles, 10 pyrazines, 9 pyridines, 3 imidazole-pyrroles, explain additionally 9-69% absorption, mainly involve four previously unrecognized ammonia methylglyoxal dimer pyrroles. The also shows remarkable on transformation chromophores; e.g., increase from 5.0 to 7.0, contributions imidazoles decrease 72% 65%, while pyrazines 5% 13% + reaction; meanwhile, more small nitrogen heterocycles transformed into oligomers (e.g., C9 C12 pyrroles) via reaction methylglyoxal. These proposed pathways instructive future field studies aqueous-phase BrC.

Language: Английский

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Enhanced Light Absorption and Elevated Viscosity of Atmospheric Brown Carbon through Evaporation of Volatile Components

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(17), P. 7493 - 7504

Published: April 18, 2024

Samples of brown carbon (BrC) material were collected from smoke emissions originating wood pyrolysis experiments, serving as a proxy for BrC representative biomass burning emissions. The acquired samples, referred to "pyrolysis oil (PO

Language: Английский

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Secondary Brown Carbon Formation From Photooxidation of Furans From Biomass Burning

Geophysical Research Letters, Journal Year: 2024, Volume and Issue: 51(1)

Published: Jan. 4, 2024

Abstract Furans are a major class of volatile organic compounds emitted from biomass burning. Their high reactivity with atmospheric oxidants leads to the formation secondary aerosol (SOA), including brown carbon (BrC) that can affect global climate via interactions solar radiation. Here, we investigate optical properties and chemical composition SOA generated photooxidation furfural, 2‐methylfuran, 3‐methylfuran under dry (RH < 5%) humid ∼ 50%) conditions in presence nitrogen oxides (NO x ) ammonium sulfate seed aerosol. Dry furfural oxidation has greatest BrC formation, reduced nitrogen‐containing (NOCs) SOA, which dominated by amines amides formed reactions between carbonyls ammonia/ammonium. Based on products detected, propose novel pathways NOCs photooxidation, contribute accretion during photochemical aging burning plumes.

Language: Английский

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