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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Large contribution of fossil-derived components to aqueous secondary organic aerosols in China

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: Aug. 31, 2022

Incomplete understanding of the sources secondary organic aerosol (SOA) leads to large uncertainty in both air quality management and climate change assessment. Chemical reactions occurring atmospheric aqueous phase represent an important source SOA mass, yet, effects anthropogenic emissions on (aqSOA) are not well constrained. Here we use compound-specific dual-carbon isotopic fingerprints (δ13C Δ14C) dominant aqSOA molecules, such as oxalic acid, track precursor formation mechanisms aqSOA. Substantial stable carbon isotope fractionation molecules provides robust evidence for extensive aqueous-phase processing. Contrary paradigm that these compounds largely biogenic, radiocarbon-based apportionments show fossil precursors produced over one-half molecules. Large fractions fossil-derived contribute substantially total water-soluble load hence impact projections radiative forcing. Our findings reveal importance with quality.

Language: Английский

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Impacts of severe residential wood burning on atmospheric processing, water-soluble organic aerosol and light absorption, in an inland city of Southeastern Europe

Atmospheric Environment, Journal Year: 2022, Volume and Issue: 280, P. 119139 - 119139

Published: May 2, 2022

Language: Английский

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Observation-based estimates of the mass absorption cross-section of black and brown carbon and their contribution to aerosol light absorption in East Asia

Atmospheric Environment, Journal Year: 2019, Volume and Issue: 212, P. 65 - 74

Published: May 14, 2019

Language: Английский

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Source Quantification of South Asian Black Carbon Aerosols with Isotopes and Modeling

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 54(19), P. 11771 - 11779

Published: Sept. 4, 2020

Black carbon (BC) aerosols perturb climate and impoverish air quality/human health—affecting ∼1.5 billion people in South Asia. However, the lack of source-diagnostic observations BC is hindering evaluation uncertain bottom-up emission inventories (EIs) thereby also models/policies. Here, we present dual-isotope-based (Δ14C/δ13C) fingerprinting wintertime at two receptor sites continental outflow. Our results show a remarkable similarity contributions biomass fossil combustion, both from site capturing highly populated polluted Indo-Gangetic Plain footprint (IGP; Δ14C-fbiomass = 50 ± 3%) second N. Indian Ocean representing wider Asian (52 6%). Yet, reflect distinct δ13C-fingerprints, indicating distinguishable contribution C4-biomass burning peninsular India (PI). Tailored-model-predicted season-averaged concentrations (700 440 ng m–3) match (740 250 m–3), however, unveiling systematically increasing model-observation bias (+19% to −53%) through winter. Inclusion open alone does not reconcile predictions (fbiomass 44 8%) with observations. Direct source-segregated comparison reveals regional offsets anthropogenic fluxes EIs, overestimated fossil-BC IGP, underestimated biomass-BC PI, which contributes bias. This ground-truthing pinpoints uncertainties sources, benefit climate/air-quality modeling mitigation policies

Language: Английский

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Absorption properties and forcing efficiency of light-absorbing water-soluble organic aerosols: Seasonal and spatial variability

Environmental Pollution, Journal Year: 2020, Volume and Issue: 272, P. 115932 - 115932

Published: Nov. 18, 2020

Language: Английский

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Characterization of carbonaceous aerosols in Singapore: insight from black carbon fragments and trace metal ions detected by a soot particle aerosol mass spectrometer

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(10), P. 5977 - 5993

Published: May 20, 2020

Abstract. Understanding sources and atmospheric processes that can influence the physiochemical properties of carbonaceous aerosols is essential to evaluate their impacts on air quality climate. However, resolving sources, emission characteristics, aging in complex urban environments remains challenging. In this work, a soot particle aerosol mass spectrometer (SP-AMS) was deployed characterize organic (OAs), refractory black carbon (rBC), trace metals Singapore, highly urbanized city with multiple local regional pollution tropical region. rBC (C1+–C9+) fragments metal ions (K+, Na+, Ni+, V+, Rb+) were integrated into our positive matrix factorization OA. Two types fossil fuel combustion-related OAs different degrees oxygenation identified. This work provides evidence over 90 % originated from combustion major part related traffic ∼30 associated fresh secondary (SOA) produced under shipping industrial activities (e.g., refineries petrochemical plants) during daytime. The results also show ∼43 total emitted traffic, while rest fraction stemmed including vehicular shipping, emissions, but not fully resolved. There only weak association cooking-related OA component rBC. Although there no observable biomass burning episode sampling period, K+ Rb+ mainly more oxidized oxygenated component, indicating potential contribution and/or coal emissions aged component. Furthermore, pollutants transported area ports presented higher C1+/C3+ V+/Ni+ ratios than those traffic. observed between Na+ suggests anthropogenic particulate sodium should be ignored coastal environments. Overall, demonstrates improve understanding history (OA rBC) type environment.

Language: Английский

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Amplification of black carbon light absorption induced by atmospheric aging: temporal variation at seasonal and diel scales in urban Guangzhou

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(4), P. 2445 - 2470

Published: Feb. 28, 2020

Abstract. Black carbon (BC) aerosols have been widely recognized as a vital climate forcer in the atmosphere. Amplification of light absorption can occur due to coatings on BC during atmospheric aging, an effect that remains uncertain accessing radiative forcing BC. Existing studies enhancement factor (Eabs) poor coverage both seasonal and diurnal scales. In this study, we applied recently developed minimum R squared (MRS) method, which cover scales, for Eabs quantification. Using field measurement data Guangzhou, aims study are explore (1) temporal dynamics optical properties at (wet season, 31 July–10 September; dry 15 November 2017–15 January 2018) diel scales (1 h time resolution) typical urban environment (2) influencing factors variability. Mass efficiency 520 nm by primary (MAEp520) determined MRS method exhibited strong seasonality (8.6 m2 g−1 wet season 16.8 season). Eabs520 was higher (1.51±0.50) lower (1.29±0.28). Absorption Ångström exponent (AAE470–660) (1.46±0.12) than (1.37±0.10). Collective evidence showed active biomass burning (BB) effectively altered BC, leading elevated MAE, MAEp AAE compared those season. Diurnal positively correlated with AAE470–660 (R2=0.71) negatively AE33 aerosol loading compensation parameter (k) (R2=0.74) but these correlations were significantly weaker may be related impact BB. This result suggests lensing more likely dominating variability rather contribution from brown (BrC). Secondary processing affect dynamics. The clear dependency ratio secondary organic (SOC∕OC), confirming Eabs; well nitrate dependence temperature. new finding implies gas–particle partitioning semivolatile compounds potentially play important role steering fluctuation Eabs520. associated photochemical aging evidenced good correlation (R2=0.69) between oxidant concentrations (Ox=O3+NO2)

Language: Английский

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Molecular Characterization of Water‐Soluble Brown Carbon Chromophores in Beijing, China

Journal of Geophysical Research Atmospheres, Journal Year: 2020, Volume and Issue: 125(15)

Published: June 30, 2020

Abstract High abundance and strong light absorption of atmospheric brown carbon (BrC) have been reported in East Asia, especially northern China. However, the molecular‐level understanding BrC chromophores this area is still limited quite challenging. In study, elemental composition individual was first investigated megacity Beijing, China, using a powerful platform for characterization chromophores, with combination high‐performance liquid chromatography coupled to UV/Vis absorbance detector time‐of‐flight mass spectrometer an electrospray ionization source. The results from study showed that S‐containing compounds (e.g., CHOS CHONS) significantly increased highly polluted days compared lightly days, probably due emissions sources such as coal combustion favorable conditions organosulfates formation. It found CHON CHO were most abundant water‐soluble organic Beijing during wintertime. Nitroaromatic major three C 6 H 5 NO 3 , 7 4 ) under all conditions, while other specific CHON‐ CHO‐containing formulas identified varied different seasons pollution conditions. Overall, explained about 2%–18% bulk over wavelength range 300–400 nm. In‐depth studies on exploring more well their chemical structures, related sources, formation mechanisms should be conducted future.

Language: Английский

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Sources and atmospheric processing of brown carbon and HULIS in the Indo-Gangetic Plain: Insights from compositional analysis

Environmental Pollution, Journal Year: 2020, Volume and Issue: 267, P. 115440 - 115440

Published: Aug. 19, 2020

Language: Английский

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