No evidence for brown carbon formation in ambient particles undergoing atmospherically relevant drying

2020 ◽  
Vol 22 (2) ◽  
pp. 442-450 ◽  
Author(s):  
Vikram Pratap ◽  
Michael A. Battaglia ◽  
Annmarie G. Carlton ◽  
Christopher J. Hennigan
Keyword(s):  
Carbon Formation ◽  
Brown Carbon ◽  
Ambient Particles ◽  
First Time ◽  
Atmospherically Relevant

This work shows, for the first time, that brown carbon formation is not observed in ambient particles undergoing drying.

scholarly journals Aging of atmospheric aerosols and the role of iron in catalyzing brown carbon formation

2021 ◽  
Author(s):  
Hind A. A. Al-Abadleh
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Atmospheric Aerosols ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Atmospheric Oxidation ◽  
Carbon Formation ◽  
Brown Carbon ◽  
Volatile Organic

Extensive research has been done on the processes that lead to the formation of secondary organic aerosol (SOA) including atmospheric oxidation of volatile organic compounds (VOCs) from biogenic and anthropogenic...

Effect of Relative Humidity on Secondary Brown Carbon Formation in Aqueous Droplets

2020 ◽  
Vol 54 (20) ◽  
pp. 13207-13216
Author(s):  
Nethmi Y. Kasthuriarachchi ◽  
Laura-Hélèna Rivellini ◽  
Xi Chen ◽  
Yong Jie Li ◽  
Alex K. Y. Lee
Keyword(s):  
Relative Humidity ◽  
Carbon Formation ◽  
Brown Carbon

scholarly journals Direct radiative effect by brown carbon over the Indo-Gangetic Plain

2015 ◽  
Vol 15 (22) ◽  
pp. 12731-12740 ◽  
Author(s):  
A. Arola ◽  
G. L. Schuster ◽  
M. R. A. Pitkänen ◽  
O. Dubovik ◽  
H. Kokkola ◽  
...  
Keyword(s):  
Winter Season ◽  
Carbonaceous Aerosols ◽  
Radiative Effect ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Relative Significance ◽  
Aerosol Absorption ◽  
Spectrally Resolved ◽  
First Time ◽  
Indo Gangetic Plain

Abstract. The importance of light-absorbing organic aerosols, often called brown carbon (BrC), has become evident in recent years. However, there have been relatively few measurement-based estimates for the direct radiative effect of BrC so far. In earlier studies, the AErosol RObotic NETwork (AERONET)-measured aerosol absorption optical depth (AAOD) and absorption Angstrom exponent (AAE) were exploited. However, these two pieces of information are clearly not sufficient to separate properly carbonaceous aerosols from dust, while imaginary indices of refraction would contain more and better justified information for this purpose. This is first time that the direct radiative effect (DRE) of BrC is estimated by exploiting the AERONET-retrieved imaginary indices. We estimated it for four sites in the Indo-Gangetic Plain (IGP), Karachi, Lahore, Kanpur and Gandhi College. We found a distinct seasonality, which was generally similar among all the sites, but with slightly different strengths. The monthly warming effect up to 0.5 W m−2 takes place during the spring season. On the other hand, BrC results in an overall cooling effect in the winter season, which can reach levels close to −1 W m−2. We then estimated similarly also the DRE of black carbon and total aerosol, in order to assess the relative significance of the BrC radiative effect in the radiative effects of other components. Even though BrC impact seems minor in this context, we demonstrated that it is not insignificant. Moreover, we demonstrated that it is crucial to perform spectrally resolved radiative transfer calculations to obtain good estimates for the DRE of BrC.

Brown Carbon Formation from Nighttime Chemistry of Unsaturated Heterocyclic Volatile Organic Compounds

2019 ◽  
Vol 6 (3) ◽  
pp. 184-190 ◽  
Author(s):  
Huanhuan Jiang ◽  
Alexander L. Frie ◽  
Avi Lavi ◽  
Jin Y. Chen ◽  
Haofei Zhang ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Carbon Formation ◽  
Brown Carbon ◽  
Nighttime Chemistry ◽  
Volatile Organic

scholarly journals Glyoxal's impact on dry ammonium salts: fast and reversible surface aerosol browning

2020 ◽  
Author(s):  
David O. De Haan ◽  
Lelia N. Hawkins ◽  
Kevin Jansen ◽  
Hannah G. Welsh ◽  
Raunak Pednekar ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Gas Phase ◽  
Ammonium Sulfate ◽  
Aerosol Particles ◽  
Ammonium Salts ◽  
Carbon Formation ◽  
Cloud Droplets ◽  
Brown Carbon ◽  
Dicarbonyl Compounds ◽  
Dry Conditions

Abstract. Alpha-dicarbonyl compounds are believed to form brown carbon in the atmosphere via reactions with ammonium sulfate (AS) in cloud droplets and aqueous aerosol particles. In this work, brown carbon formation in AS and other aerosol particles was quantified as a function of relative humidity (RH) during exposure to gas-phase glyoxal (GX) in chamber experiments. Under dry conditions (RH 

A theoretical study of the mechanism of the atmospherically relevant reaction of chlorine atoms with methyl nitrate, and calculation of the reaction rate coefficients at temperatures relevant to the troposphere

2015 ◽  
Vol 17 (11) ◽  
pp. 7463-7476 ◽  
Author(s):  
Maggie Ng ◽  
Daniel K. W. Mok ◽  
Edmond P. F. Lee ◽  
John M. Dyke
Keyword(s):  
Reaction Rate ◽  
Theoretical Study ◽  
Rate Coefficients ◽  
Chlorine Atoms ◽  
Methyl Nitrate ◽  
First Time ◽  
Atmospherically Relevant

Computed rate coefficients of the atmospherically important Cl + CH3ONO2 → HCl + CH2ONO2 reaction reported for the first time.

scholarly journals Evidence for Polarity- and Viscosity-Controlled Domains in the Termination Reaction in the Radical Polymerization of Acrylonitrile

2021 ◽  
Author(s):  
Xiaopei Lin ◽  
Tasuku Ogihara ◽  
Tatsuhisa Kato ◽  
Yasuyuki Nakamura ◽  
Shigeru Yamago
Keyword(s):  
Radical Polymerization ◽  
Bond Formation ◽  
Carbon Formation ◽  
Molding Process ◽  
Processing Step ◽  
The Media ◽  
Small Model ◽  
First Time ◽  
Polymerization Conditions ◽  
Nitrogen Bond

The termination mechanism in the radical polymerization of acrylonitrile (AN) was determined by the reaction of structurally well-defined polyacryronitrile (PAN) chain-end radical <b>1a</b> and PAN-end mimetic small model radical <b>1b</b>. The contributions of three mechanisms, i.e., the disproportionation (<i>Disp</i>), the combination by carbon-carbon formation (<i>CC-Comb</i>), and the combination by carbon-nitrogen bond formation (<i>CN-Comb</i>), were unambiguously determined. The <i>CN-Comb</i> pathway was experimentally proved for the first time. The selectivity between <i>Disp </i>and<i> CC-Comb</i> showed a good correlation with the viscosity and temperature, and the <i>Disp</i> selectivity increased as the viscosity increased, as previously reported for the termination of other monomers. In contrast, <i>CN-Comb</i> is insensitive to viscosity but sensitive to polarity; the selectivity decreases as the polarity of the media increases. The results strongly suggest the presence of two domains in the termination reaction, namely, the polarity- and viscosity-controlled domains. <i>CN-Comb</i> product<b> 5</b> was stable under the polymerization conditions but decomposed to <i>Disp</i> and <i>CC-Comb</i> products at high temperatures. Therefore, care must be taken in the processing step, such as the molding process, because the physical properties could be altered due to changes in the <i>Disp</i> and <i>CC-Comb</i> compositions.

scholarly journals Heterogeneous OH oxidation of secondary brown carbon aerosol

2018 ◽  
Author(s):  
Elijah G. Schnitzler ◽  
Jonathan P. D. Abbatt
Keyword(s):  
Optical Properties ◽  
Single Scattering ◽  
Trace Gas ◽  
Absorption Enhancement ◽  
Brown Carbon ◽  
Scattering Coefficients ◽  
Aerosol Absorption ◽  
In Series ◽  
First Time ◽  
Slow Absorption

Abstract. Light-absorbing organic aerosol, or brown carbon (BrC), has significant but poorly-constrained effects on climate; for example, oxidation in the atmosphere may alter its optical properties, leading to absorption enhancement or bleaching. Here, we investigate for the first time the effects of heterogeneous OH oxidation on the optical properties of a laboratory surrogate of secondary BrC in a series of photo-oxidation chamber experiments. The BrC surrogate was generated from aqueous resorcinol, or 1,3-dihydroxybenzene, and H2O2 exposed to > 300 nm radiation, atomized, passed through trace gas denuders, and injected into the chamber, which was conditioned to either 15 or 60 % relative humidity (RH). Aerosol absorption and scattering coefficients and single scattering albedo (SSA) at 405 nm were measured using a photo-acoustic spectrometer. At 60 % RH, upon OH exposure, absorption first increased, and the SSA decreased sharply. Subsequently, absorption decreased faster than scattering, and SSA increased gradually. Comparisons to the modelled trend in SSA, based on Mie theory calculations, confirm that the observed trend is due to chemical evolution, rather than slight changes in particle size. The initial absorption enhancement is likely due to molecular functionalization and/or oligomerization, and the bleaching to fragmentation. By contrast, at 15 % RH, slow absorption enhancement was observed, without appreciable bleaching. A multi-layer kinetics model, consisting of two surface reactions in series, was constructed to provide further insights regarding the RH-dependence of the optical evolution. Candidate parameters suggest that the oxidation is efficient, with uptake coefficients on the order of unity, and the aerosol is very viscous, even at 60 % RH. At 15 % RH, the aerosol will be viscous enough to confine products of fragmentation, leading to their recombination, such that little bleaching is observed on the experimental timescale. These results further the current understanding of the complex processing of BrC that may occur in the atmosphere.

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