Two-year-long high-time-resolution apportionment of primary and secondary carbonaceous aerosols in the Los Angeles Basin using an advanced total carbon–black carbon (TC-BC(λ)) method DOI Creative Commons
Matic Ivančič, Asta Gregorič,

Gašper Lavrič

et al.

The Science of The Total Environment, Journal Year: 2022, Volume and Issue: 848, P. 157606 - 157606

Published: July 25, 2022

In recent years, carbonaceous aerosols (CA) have been recognized as a significant contributor to the concentration of particles smaller than 2.5 μm (i.e., PM2.5), with negative impact on public health and Earth's radiative balance. this study, we present method for CA apportionment based high-time-resolution measurements total carbon (TC), black (BC), spectral dependence absorption coefficient using recently developed Carbonaceous Aerosol Speciation System (CASS). Two-year-long at two different locations within California's Los Angeles Basin are presented. was apportioned its optical properties, organic or elemental composition, primary secondary origin. We found that (SOA), average, represent >50 % in study area, presumably resulting from oxidation anthropogenic biogenic volatile components. Remarkable peaks SOA summer afternoons were observed, fractional contribution up 90 %. On other hand, peak emitted CA, consisting BC aerosol (POA), contributed >80 during morning rush hours winter working days. The light dominated over brown (BrC), which 20 10 lower wavelength 370 nm nights afternoons, respectively. highest BrC, 50 %, observed wildfire periods. Although uncertainty levels can be high some components (such split between formed BrC nights), further research focused properties may help better constrain parameters used studies. believe CASS system combined presented offer simplified cost-effective insights into composition aerosols.

Language: Английский

Molecular-Level Study of the Photo-Oxidation of Aqueous-Phase Guaiacyl Acetone in the Presence of 3C*: Formation of Brown Carbon Products DOI
Maria V. Misovich, Anusha P. S. Hettiyadura, Wenqing Jiang

et al.

ACS Earth and Space Chemistry, Journal Year: 2021, Volume and Issue: 5(8), P. 1983 - 1996

Published: Aug. 3, 2021

This study examined the effects of simulated solar irradiation on a model system atmospheric aqueous secondary organic aerosol (aqSOA) formed from oxidation guaiacyl acetone (GA) by reactions with triplet excited carbon (3C*) generated photoexcitation 3,4-dimethoxybenzaldehyde (DMB). Both GA and DMB are common components biomass burning emissions, their mixture was selected as case to investigate influence aqueous-phase photochemistry light absorption properties brown (BrC) pertinent aqSOA formation. Irradiation performed in photoreactor designed mimic sunlight irradiation, samples were collected at different times experiment, which lasted for 6 h. Chemical separated using high-performance liquid chromatography analyzed photodiode array detector Orbitrap mass spectrometer operated simultaneously record both UV–visible spectra high-resolution spectra. allowed us obtain molecular characterization individual components, well information light-absorbing how they change over time when irradiated. The results indicate that three generations products stages experiment: monomeric products, dimeric less polar aromatic similar those during oxygen-deprived pyrolytic processes. result initiated 3C*, while form radical recombination. Prior BrC absorbance is dominated species, but it later pyrolytic-like begin photodegrade. Comparison previously defined classes based optical suggests this experiment initially fall outside these then become more absorbing, consistent "very weak" "weak" classes.

Language: Английский

Citations

53
Brownness of Organic Aerosol over the United States: Evidence for Seasonal Biomass Burning and Photobleaching Effects DOI
L.‐W. Antony Chen, Judith C. Chow, Xiaoliang Wang

et al.

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(13), P. 8561 - 8572

Published: June 15, 2021

Light-absorptivity of organic aerosol may play an important role in visibility and climate forcing, but it has not been assessed as extensively black carbon (BC) aerosol. Based on multiwavelength thermal/optical analysis spectral mass balance, this study quantifies BC for the U.S. Interagency Monitoring Protected Visual Environments (IMPROVE) network while developing a brownness index (γBr) non-BC (OC*) to illustrate spatiotemporal trends light-absorbing brown (BrC) content. OC* light absorption efficiencies range from 0 3.1 m2 gC-1 at 405 nm, corresponding lowest highest BrC content 100%, respectively. BC, OC*, γBr explain >97% variability measured (405-980 nm) across 158 IMPROVE sites. Network-average absorptions nm are 50 28% those over rural urban areas, Larger fractions occur winter, partially due higher brownness. Winter exhibits dramatic regional/urban-rural contrast consistent with anthropogenic emissions residential wood combustion. The spatial differences diminish uniformly low summer, suggesting effective photobleaching midlatitudes. An empirical relationship between ambient temperature, is established, which can facilitate incorporation absorptivity into models that currently assume either zero or static efficiencies.

Language: Английский

Citations

52
Source-specific light absorption by carbonaceous components in the complex aerosol matrix from yearly filter-based measurements DOI Creative Commons
Vaios Moschos, Martin Gysel‐Beer, Robin L. Modini

et al.

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(17), P. 12809 - 12833

Published: Aug. 31, 2021

Abstract. Understanding the sources of light-absorbing organic (brown) carbon (BrC) and its interaction with black (BC) other non-refractory particulate matter (NR-PM) fractions is important for reducing uncertainties in aerosol direct radiative forcing. In this study, we combine multiple filter-based techniques to achieve long-term, spectrally resolved, source- species-specific atmospheric absorption closure. We determine mass efficiency (MAE) dilute bulk solutions at 370 nm be equal 1.4 m2 g−1 fresh biomass smoke, 0.7 winter-oxygenated (OA), 0.13 less absorbing OA. apply Mie calculations estimate contributions these total absorption. While enhanced near-UV has been traditionally attributed primary here show that anthropogenic oxygenated OA may equally BrC during winter, especially an urban background site. demonstrate insoluble tar balls are negligible residential burning samples study thus could attribute totality NR-PM shorter wavelengths methanol-extractable BrC. As BC, cross-section (MAC) fraction independent source, while observe evidence a lensing effect associated presence components. find bare BC MAC 6.3 660 Ångström exponent 0.93 ± 0.16, coatings by factor ∼ 1.4. Based on closure between observed predicted light absorption, provide indication suppression The reduction remains modest, 10 %–20 % nm, restricted wavelengths, where significant. Overall, our results allow assessment relative importance different aerosols from wide range ages. When integrated solar spectrum 300–900 found contribute around two-thirds radiation carbonaceous aerosols, amplified (with interquartile range, IQR, 8 %–27 %), IQR 6 %–13 (13 rural site winter). Future studies will directly benefit include (a) optical modelling aiming understanding profiles complex composed BrC, lensing-inducing coatings; (b) source apportionment profiles; (c) global quantifying most absorbers.

Language: Английский

Citations

43
Connecting the Light Absorption of Atmospheric Organic Aerosols with Oxidation State and Polarity DOI
Xiaotong Jiang, Dantong Liu, Qian Li

et al.

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(18), P. 12873 - 12885

Published: Sept. 9, 2022

The light-absorbing organic aerosol (OA) constitutes an important fraction of absorbing components, counteracting major cooling effect aerosols to climate. mechanisms in linking the complex and changeable chemistry OA with its properties remain be elucidated. Here, by using solvent extraction, ambient from urban environment was fractionated according polarity, which further nebulized online characterized compositions properties. Water extracted high-polar compounds a significantly higher oxygen carbon ratio (O/C) than methanol extracts. A transition O/C about 0.6 found, below above enhancement reduction absorptivity were observed increasing O/C, occurring on less polar high compounds, respectively. In particular, co-increase nitrogen elements suggests role nitrogen-containing functional groups enhancing (e.g., forming aromatics), while oxidation (O/C > 0.6) likely led fragmentation bleaching chromophores. results here may reconcile previous observations darkening or whitening chromophores brown carbon, parametrization has potential link changing polarity

Language: Английский

Citations

36
Two-year-long high-time-resolution apportionment of primary and secondary carbonaceous aerosols in the Los Angeles Basin using an advanced total carbon–black carbon (TC-BC(λ)) method DOI Creative Commons
Matic Ivančič, Asta Gregorič,

Gašper Lavrič

et al.

The Science of The Total Environment, Journal Year: 2022, Volume and Issue: 848, P. 157606 - 157606

Published: July 25, 2022

In recent years, carbonaceous aerosols (CA) have been recognized as a significant contributor to the concentration of particles smaller than 2.5 μm (i.e., PM2.5), with negative impact on public health and Earth's radiative balance. this study, we present method for CA apportionment based high-time-resolution measurements total carbon (TC), black (BC), spectral dependence absorption coefficient using recently developed Carbonaceous Aerosol Speciation System (CASS). Two-year-long at two different locations within California's Los Angeles Basin are presented. was apportioned its optical properties, organic or elemental composition, primary secondary origin. We found that (SOA), average, represent >50 % in study area, presumably resulting from oxidation anthropogenic biogenic volatile components. Remarkable peaks SOA summer afternoons were observed, fractional contribution up 90 %. On other hand, peak emitted CA, consisting BC aerosol (POA), contributed >80 during morning rush hours winter working days. The light dominated over brown (BrC), which 20 10 lower wavelength 370 nm nights afternoons, respectively. highest BrC, 50 %, observed wildfire periods. Although uncertainty levels can be high some components (such split between formed BrC nights), further research focused properties may help better constrain parameters used studies. believe CASS system combined presented offer simplified cost-effective insights into composition aerosols.

Language: Английский

Citations

30