Molecular Chemistry of Atmospheric Brown Carbon Inferred from a Nationwide Biomass Burning Event

Environmental Science & Technology, Journal Year: 2017, Volume and Issue: 51(20), P. 11561 - 11570

Published: July 31, 2017

Lag Ba'Omer, a nationwide bonfire festival in Israel, was chosen as case study to investigate the influence of major biomass burning event on light absorption properties atmospheric brown carbon (BrC). The chemical composition and optical BrC chromophores were investigated using high performance liquid chromatography (HPLC) platform coupled photo diode array (PDA) resolution mass spectrometry (HRMS) detectors. Substantial increase coefficient observed during night-long event. Most attributed nitroaromatic compounds (NAC), comprising 28 elemental formulas at least 63 structural isomers. NAC, combination, accounted for 50-80% total visible (>400 nm) by solvent extractable BrC. results highlight that particular nitrophenols, are important contributors organic aerosol (BBOA), suggesting night time chemistry •NO3 N2O5 with particles may play significant role transformations Nitrophenols related especially BBOA. spectra influenced extraction solution pH, implying acidity is an factor controlling

Language: Английский

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Comprehensive Molecular Characterization of Atmospheric Brown Carbon by High Resolution Mass Spectrometry with Electrospray and Atmospheric Pressure Photoionization

Analytical Chemistry, Journal Year: 2018, Volume and Issue: 90(21), P. 12493 - 12502

Published: Oct. 8, 2018

Light-absorbing components of atmospheric organic aerosols, which are collectively termed "brown carbon" (BrC), ubiquitous in the atmosphere. They affect absorption solar radiation by aerosols atmosphere and human health as some them have been identified potential toxins. Understanding sources, formation, evolution, environmental effects BrC requires molecular identification characterization light-absorption properties chromophores. Identification is challenging due to complexity aerosols. In this study, we employ two complementary ionization techniques, pressure photo (APPI) electrospray (ESI), obtain broad coverage both polar nonpolar using high-resolution mass spectrometry (HRMS). These techniques combined with chromatographic separation compounds high performance liquid chromatography (HPLC), their light a photodiode array (PDA) detector, chemical composition HRMS. We demonstrate that approach enables more comprehensive biomass burning (BBOAs) emitted from test burns sage brush biofuel. particular, found chromophores such PAHs only detected positive mode APPI. Meanwhile, negative ESI results detection nitroaromatics, aromatic acids, phenols. For material examined over 40% solvent-extractable attributed water insoluble, semipolar derivatives, require APPI for identification. contrast, polar, water-soluble compounds, ESI, account less than 30% BrC.

Language: Английский

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Changes in Light Absorptivity of Molecular Weight Separated Brown Carbon Due to Photolytic Aging

Environmental Science & Technology, Journal Year: 2017, Volume and Issue: 51(15), P. 8414 - 8421

Published: June 22, 2017

Brown carbon (BrC) consists of those organic compounds in atmospheric aerosols that absorb solar radiation and may play an important role planetary radiative forcing climate. However, little is known about the production loss mechanisms BrC atmosphere. Here, we study how light absorptivity from wood smoke secondary generated reaction ammonium sulfate with methylglyoxal changes under photolytic aging by UVA aqueous phase. Owing to its chemical complexity, separated molecular weight using size exclusion chromatography, response each fraction studied. Photolytic induced significant for all fractions; was rapidly photoblenched, whereas BrC, both photoenhancement photobleaching were observed. Initially, large biomass burning molecules photoenhanced, followed slow photolysis. As a result, dominated total absorption aged BrC. These experimental results further support earlier observations can be relatively long-lived components aerosols, thus more likely have larger impacts on aerosol could serve as tracers.

Language: Английский

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Brown Carbon Aerosol in Urban Xi’an, Northwest China: The Composition and Light Absorption Properties

Environmental Science & Technology, Journal Year: 2018, Volume and Issue: 52(12), P. 6825 - 6833

Published: May 25, 2018

Light-absorbing organic carbon (i.e., brown or BrC) in the atmospheric aerosol has significant contribution to light absorption and radiative forcing. However, link between BrC optical properties chemical composition remains poorly constrained. In this study, we combine spectrophotometric measurements analyses of samples collected from July 2008 June 2009 urban Xi'an, Northwest China. Elevated was observed winter (5 times higher than summer), largely due increased emissions wintertime domestic biomass burning. The coefficient methanol-soluble at 365 nm (on average approximately twice that water-soluble found correlate strongly with both parent polycyclic aromatic hydrocarbons (parent-PAHs, 27 species) their carbonyl oxygenated derivatives (carbonyl-OPAHs, 15 all seasons (r2 > 0.61). These measured parent-PAHs carbonyl-OPAHs account for on ∼1.7% overall BrC, about 5 mass fraction total (OC, ∼0.35%). fractional solar by relative element (EC) ultraviolet range (300–400 nm) is during (42 ± 18% 76 29% BrC), which may greatly affect balance tropospheric photochemistry therefore climate air quality.

Language: Английский

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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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Light Absorption of Secondary Organic Aerosol: Composition and Contribution of Nitroaromatic Compounds

Environmental Science & Technology, Journal Year: 2017, Volume and Issue: 51(20), P. 11607 - 11616

Published: Sept. 20, 2017

Secondary organic aerosol (SOA) can affect the atmospheric radiation balance through absorbing light at shorter visible and UV wavelengths. However, composition optical properties of light-absorbing SOA is poorly understood. In this work, filter samples were collected during individual chamber experiments conducted with three biogenic eight aromatic volatile compound (VOC) precursors in presence NOX H2O2. Compared generated using precursors, generally exhibits negligible absorption above 350 nm; shows stronger than that Fifteen nitroaromatic (NAC) chemical formulas identified quantified samples. Their contributions to sample extracts also estimated. On average, m-cresol/NOX has highest mass contribution from NACs (10.4 ± 6.74%, w/w), followed by naphthalene/NOX (6.41 2.08%) benzene/NOX (5.81 3.82%) SOA. The average total least two times greater their 365 400 nm, revealing potential use chromophoric as brown carbon (BrC) tracers source apportionment air quality modeling studies.

Language: Английский

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Atmospheric Photooxidation Diminishes Light Absorption by Primary Brown Carbon Aerosol from Biomass Burning

Environmental Science & Technology Letters, Journal Year: 2017, Volume and Issue: 4(12), P. 540 - 545

Published: Sept. 21, 2017

Light-absorbing organic aerosols, optically defined as brown carbon (BrC), have been shown to strongly absorb short visible solar wavelengths and significantly impact Earth's radiative energy balance. There currently exists a knowledge gap regarding the potential impacts of atmospheric processing on absorptivity such particles generated from biomass burning. Climate models satellite retrieval algorithms parametrize optical properties BrC aerosols emitted burning events unchanging throughout their lifecycle. Here, using contact-free probing techniques, we investigate effects multiple-day photochemical oxidation spectral (375–532 nm) primary smoldering combustion boreal peatlands. We find largest in near-UV wavelengths, with 375 nm imaginary refractive index absorption coefficients decreasing by ∼36% 46%, respectively, an increase single scattering albedo 0.85 0.90. Based simultaneous chemical characterization particles, infer transition functionalization fragmentation reactions increasing photooxidation. Simple forcing efficiency calculations show aging warming attributed which could be significant over snow other reflective surfaces.

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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