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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Review of brown carbon aerosols: Recent progress and perspectives

The Science of The Total Environment, Journal Year: 2018, Volume and Issue: 634, P. 1475 - 1485

Published: April 18, 2018

Language: Английский

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Photochemical degradation affects the light absorption of water-soluble brown carbon in the South Asian outflow

Science Advances, Journal Year: 2019, Volume and Issue: 5(1)

Published: Jan. 4, 2019

Light-absorbing organic aerosols, known as brown carbon (BrC), counteract the overall cooling effect of aerosols on Earth's climate. The spatial and temporal dynamics their light-absorbing properties are poorly constrained unaccounted for in climate models, because limited ambient observations. We combine isotope forensics (δ13C) with measurements light absorption a conceptual aging model to constrain loss absorptivity (i.e., bleaching) water-soluble BrC (WS-BrC) one world's largest emission regions-South Asia. On this regional scale, we find that atmospheric photochemical oxidation reduces WS-BrC by ~84% during transport over 6000 km Indo-Gangetic Plain, an first-order bleaching rate 0.20 ± 0.05 day-1 over-ocean transit across Bay Bengal Indian Ocean receptor site. This study facilitates dynamic parameterization properties, thereby constraining impact South

Language: Английский

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From Measurements to Models: Toward Accurate Representation of Brown Carbon in Climate Calculations

Current Pollution Reports, Journal Year: 2020, Volume and Issue: 6(2), P. 90 - 104

Published: March 19, 2020

Language: Английский

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Molecular composition and photochemical lifetimes of brown carbon chromophores in biomass burning organic aerosol

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(2), P. 1105 - 1129

Published: Jan. 28, 2020

Abstract. To better understand the effects of wildfires on air quality and climate, it is important to assess occurrence chromophoric compounds in smoke characterize their optical properties. This study explores molecular composition light-absorbing organic aerosol, or brown carbon (BrC), sampled at Missoula Fire Sciences laboratory as a part FIREX Fall 2016 lab intensive. A total 12 biomass fuels from different plant types were tested, including gymnosperm (coniferous) angiosperm (flowering) plants ecosystem components such duff, litter, canopy. Emitted burning aerosol (BBOA) particles collected onto Teflon filters analyzed offline using high-performance liquid chromatography coupled photodiode array spectrophotometer high-resolution mass spectrometer (HPLC–PDA–HRMS). Separated BrC chromophores classified by retention times, absorption spectra, integrated absorbance near-UV visible spectral range (300–700 nm), chemical formulas accurate m∕z measurements. grouped into following classes subclasses: lignin-derived products, which include lignin pyrolysis products; distillation coumarins flavonoids; nitroaromatics; polycyclic aromatic hydrocarbons (PAHs). The observed subclasses common across most fuel types, although specific varied based type (gymnosperm angiosperm) component(s) burned. stability with respect photodegradation, BBOA particle samples irradiated directly near UV (300–400 nm) radiation, followed extraction HPLC–PDA–HRMS analysis. Lifetimes individual depended corresponding combustion condition. Lignin-derived flavonoid generally had longest lifetimes photodegradation. Moreover, for same depending conditions. While disappeared timescale several days, overall light sample persisted longer, presumably because condensed-phase photochemical processes converted one set another without complete photobleaching undetected that photobleached more slowly. model effect change coefficient time. We measured equivalent atmospheric coefficient, ranged 10 41 d, subalpine fir having shortest lifetime conifer canopies, i.e., juniper, lifetime. emitted loads encompassing multiple (litter, shrub, canopy) lower end range. These results indicate photochemistry relatively slow. Competing aging mechanisms, heterogeneous oxidation OH, may be controlling rate BBOA.

Language: Английский

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Molecular compositions and optical properties of dissolved brown carbon in biomass burning, coal combustion, and vehicle emission aerosols illuminated by excitation–emission matrix spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry analysis

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(4), P. 2513 - 2532

Published: March 2, 2020

Abstract. Brown carbon (BrC) plays an essential impact on radiative forcing due to its ability absorb sunlight. In this study, the optical properties and molecular characteristics of water-soluble methanol-soluble organic (OC; MSOC) emitted from simulated combustion biomass coal fuels vehicle emissions were investigated using ultraviolet–visible (UV–vis) spectroscopy, excitation–emission matrix (EEM) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with electrospray ionization (ESI). The results showed that these smoke aerosol samples burning (BB) (CC) had a higher absorption efficiency at 365 nm (MAE365) than emission samples. A stronger MAE365 value was also found in MSOC (WSOC), indicating low polar compounds would possess light capacity. Parallel factor (PARAFAC) analysis identified six types fluorophores (P1–6) WSOC including two humic-like substances (HULIS-1) (P1 P6), three protein-like (PLOM) (P2, P3, P5), one undefined substance (P4). HULIS-1 mainly aging exhaust particles; P2 only abundant BB aerosols; P3 ubiquitous all tested P4 fossil P5 more intense fresh particles. chromophores (six components; C1–6) exhibited consistent WSOC, suggesting method could be used indicate origins chromophores. FT-ICR spectra CHO CHON most components but S-containing appeared abundance CC aerosols aerosols, while considerably fewer largely detected MSOC. unique formulas different sources van Krevelen (VK) diagram presented distributions. To specific, medium H ∕ C O ratio, opposite ratio. Moreover, capacity positively associated unsaturation degree weight source aerosols. above are potentially applicable further studies EEM-based or molecular-characteristic-based apportionment atmospheric

Language: Английский

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Modeling the global radiative effect of brown carbon: a potentially larger heating source in the tropical free troposphere than black carbon

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(4), P. 1901 - 1920

Published: Feb. 20, 2020

Abstract. Carbonaceous aerosols significantly affect global radiative forcing and climate through absorption the scattering of sunlight. Black carbon (BC) brown (BrC) are light-absorbing carbonaceous aerosols. The direct effect (DRE) BrC is uncertain. A recent study suggests that comparable to BC in upper troposphere over biomass burning regions resulting heating tends stabilize atmosphere. Yet current models do not include proper physical chemical treatments BrC. In this study, we derived a emission inventory on basis Global Fire Emissions Database version 4 (GFED4), developed module simulate light Community Atmosphere Model 5 (CAM5) Earth System (CESM), investigated photobleaching convective transport Studies Emissions, Atmospheric Composition, Clouds Climate Coupling by Regional Surveys (SEAC4RS) Deep Convective Chemistry Project (DC3) measurements. model simulations were also evaluated using HIAPER (High-Performance Instrumented Airborne Platform for Environmental Research) Pole-to-Pole Observations (HIPPO) We found globally significant absorber, DRE which 0.10 W m−2, more than 25 % (+0.39 m−2). Most significantly, results indicated atmospheric tropical mid larger BC. source mainly from wildfires, prevalent higher latitudes release much relative industrial sources. While skewed towards northern mid-latitude lower atmosphere, centered free troposphere. possible mechanism enhanced hydrophobic high molecular weight becomes fraction less easily activated cloud as aerosol ages. contribution Hadley circulation latitudinal expansion tropics likely heating.

Language: Английский

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Atmospheric evolution of molecular-weight-separated brown carbon from biomass burning

Atmospheric chemistry and physics, Journal Year: 2019, Volume and Issue: 19(11), P. 7319 - 7334

Published: June 4, 2019

Abstract. Biomass burning is a major source of atmospheric brown carbon (BrC), and through its absorption UV/VIS radiation, it can play an important role in the planetary radiative balance photochemistry. The considerable uncertainty BrC impacts associated with poorly constrained sources, transformations, lifetime. Here we report laboratory experiments that examined changes optical properties water-soluble (WS) fraction laboratory-generated biomass particles from hardwood pyrolysis. Effects direct UVB photolysis OH oxidation aqueous phase on molecular-weight-separated were studied. Results indicated majority low-molecular-weight (MW) (<400 Da) was rapidly photobleached by both timescale approximately 1 h. High MW (≥400 underwent initial photoenhancement up to ∼15 h, followed slow photobleaching over ∼10 supported observations ambient samples collected during fire seasons Greece. These samples, containing freshly emitted aged aerosol, analyzed for water- methanol-soluble BrC. Consistent experiments, high-MW dominated total light at 365 nm methanol fractions transport times 68 indicate overall, across all molecular weights has lifetime 15 28 consistent estimates previous field studies – although remains relatively stable responsible throughout most For (>10 h) emissions, poor linear correlations found between absorptivity levoglucosan, other suggesting short levoglucosan. However, much stronger correlation hydrous sugars observed, they may serve as more robust tracers emissions. Overall, results this study suggest model require consideration aging stability

Language: Английский

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Aqueous Phase Photo-oxidation of Brown Carbon Nitrophenols: Reaction Kinetics, Mechanism, and Evolution of Light Absorption

ACS Earth and Space Chemistry, Journal Year: 2018, Volume and Issue: 2(3), P. 225 - 234

Published: Jan. 16, 2018

Light absorbing organic aerosol particles, referred to as brown carbon, are geographically widespread and can have an important climate impact through the absorption of solar radiation. Recent studies, both in laboratory field, shown that carbon aerosols be bleached their color by direct photolysis photo-oxidation reactions on time scale hours days. However, nitrophenol molecules, which colored compounds often associated with biomass burning aerosol, show enhancement light before is lost. This study investigates mechanism fate three compounds, specifically nitrocatechol, nitroguaiacol, dinitrophenol, aqueous phase using online chemical ionization mass spectrometry (aerosol-CIMS). The second-order rate constants for nitrophenols OH radicals at pH 7 (298 K), were determined 5 × 109 M–1 s–1, 5.2 3.7 s–1 respectively. For a representative concentration, these correspond lifetime respect order hours. While molecules react rapidly OH, initial products, functionalized additional electron-donating groups, likely lead observed increase visible range. Further fragments aromatic structure produce smaller, highly oxygenated no longer absorb strongly wavelengths. These products include furoic acid, glyoxylic malonic oxalic isocyanic acid. All investigated formed similar during photo-oxidation, suggesting results could generalized this larger class compounds.

Language: Английский

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Ambient particulate matter oxidative potential: Chemical determinants, associated health effects, and strategies for risk management

Free Radical Biology and Medicine, Journal Year: 2020, Volume and Issue: 151, P. 7 - 25

Published: May 1, 2020

Language: Английский

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