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

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 < 5 %), solid AS, AS–glycine, and methylammonium sulfate (MeAS) aerosol particles brown within minutes upon exposure to GX, while sodium sulfate particles do not. When GX concentrations decline, browning goes away, demonstrating that this dry browning process is reversible. Declines in aerosol albedo are found to be a function of [GX]2 and are consistent between AS and AS–glycine aerosol. Dry methylammonium sulfate aerosol browns 4 times more than dry AS aerosol, but deliquesced AS aerosol browns much less than dry AS aerosol. Optical measurements at 405, 450, and 530 nm provide an estimated Ångstrom absorbance coefficient of -16±4. This coefficient and the empirical relationship between GX and albedo are used to estimate an upper limit to global radiative forcing by brown carbon formed by 70 ppt GX reacting with AS (+7.6×10-5 W m−2). This quantity is < 1 % of the total radiative forcing by secondary brown carbon but occurs almost entirely in the ultraviolet range.

Download Full-text

Radical-Initiated Brown Carbon Formation in Sunlit Carbonyl–Amine–Ammonium Sulfate Mixtures and Aqueous Aerosol Particles

ACS Earth and Space Chemistry ◽

10.1021/acsearthspacechem.1c00395 ◽

2022 ◽

Author(s):

Natalie G. Jimenez ◽

Kyle D. Sharp ◽

Tobin Gramyk ◽

Duncan Z. Ugland ◽

Matthew-Khoa Tran ◽

...

Keyword(s):

Ammonium Sulfate ◽

Aerosol Particles ◽

Carbon Formation ◽

Brown Carbon

Download Full-text

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

Environmental Science & Technology ◽

10.1021/acs.est.0c01239 ◽

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

Download Full-text

Effects of relative humidity on aerosol light scattering in the Arctic

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-3875-2010 ◽

2010 ◽

Vol 10 (8) ◽

pp. 3875-3890 ◽

Cited By ~ 89

Author(s):

P. Zieger ◽

R. Fierz-Schmidhauser ◽

M. Gysel ◽

J. Ström ◽

S. Henne ◽

...

Keyword(s):

Standard Deviation ◽

Light Scattering ◽

Relative Humidity ◽

Aerosol Particles ◽

Aerosol Size Distribution ◽

Hygroscopic Growth ◽

Scattering Coefficients ◽

Dry Conditions ◽

Hygroscopic Particles

Abstract. Aerosol particles experience hygroscopic growth in the ambient atmosphere. Their optical properties – especially the aerosol light scattering – are therefore strongly dependent on the ambient relative humidity (RH). In-situ light scattering measurements of long-term observations are usually performed under dry conditions (RH>30–40%). The knowledge of this RH effect is of eminent importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. This study combines measurements and model calculations to describe the RH effect on aerosol light scattering for the first time for aerosol particles present in summer and fall in the high Arctic. For this purpose, a field campaign was carried out from July to October 2008 at the Zeppelin station in Ny-Ålesund, Svalbard. The aerosol light scattering coefficient σsp(λ) was measured at three distinct wavelengths (λ=450, 550, and 700 nm) at dry and at various, predefined RH conditions between 20% and 95% with a recently developed humidified nephelometer (WetNeph) and with a second nephelometer measuring at dry conditions with an average RH<10% (DryNeph). In addition, the aerosol size distribution and the aerosol absorption coefficient were measured. The scattering enhancement factor f(RH, λ) is the key parameter to describe the RH effect on σsp(λ) and is defined as the RH dependent σsp(RH, λ) divided by the corresponding dry σsp(RHdry, λ). During our campaign the average f(RH=85%, λ=550 nm) was 3.24±0.63 (mean ± standard deviation), and no clear wavelength dependence of f(RH, λ) was observed. This means that the ambient scattering coefficients at RH=85% were on average about three times higher than the dry measured in-situ scattering coefficients. The RH dependency of the recorded f(RH, λ) can be well described by an empirical one-parameter equation. We used a simplified method to retrieve an apparent hygroscopic growth factor g(RH), defined as the aerosol particle diameter at a certain RH divided by the dry diameter, using the WetNeph, the DryNeph, the aerosol size distribution measurements and Mie theory. With this approach we found, on average, g(RH=85%) values to be 1.61±0.12 (mean±standard deviation). No clear seasonal shift of f(RH, λ) was observed during the 3-month period, while aerosol properties (size and chemical composition) clearly changed with time. While the beginning of the campaign was mainly characterized by smaller and less hygroscopic particles, the end was dominated by larger and more hygroscopic particles. This suggests that compensating effects of hygroscopicity and size determined the temporal stability of f(RH, λ). During sea salt influenced periods, distinct deliquescence transitions were observed. At the end we present a method on how to transfer the dry in-situ measured aerosol scattering coefficients to ambient values for the aerosol measured during summer and fall at this location.

Download Full-text

Laboratory study of the collection efficiency of submicron aerosol particles by cloud droplets. Part I – Influence of relative humidity

10.5194/acp-2020-831 ◽

2020 ◽

Cited By ~ 1

Author(s):

Alexis Dépée ◽

Pascal Lemaitre ◽

Thomas Gelain ◽

Marie Monier ◽

Andrea Flossmann

Keyword(s):

Relative Humidity ◽

High Efficiency ◽

Collection Efficiency ◽

Aerosol Particles ◽

Droplet Radius ◽

Sodium Fluorescein ◽

Extended Model ◽

Cloud Droplets ◽

Submicron Aerosol ◽

The Impact

Abstract. A new In-Cloud Aerosol Scavenging Experiment (In-CASE) has been conceived to measure the collection efficiency (CE) of submicron aerosol particles by cloud droplets. In this setup, droplets fall at their terminal velocity through a one-meter-high chamber in a laminar flow containing aerosol particles. At the bottom of the In-CASE's chamber, the droplet train is separated from the aerosol particle flow – droplets are collected in an impaction cup whereas aerosol particles are deposited on a High Efficiency Particulate Air (HEPA) filter. The collected droplets and the filter are then analysed by fluorescence spectrometry since the aerosol particles are atomised from a sodium fluorescein salt solution (C20H10Na2O5). In-CASE fully controls all the parameters which affect the CE – the droplets and aerosol particles size distributions are monodispersed, the electric charges of droplets and aerosol particles are controlled, while the relative humidity is indirectly set via the chamber's temperature. This novel In-CASE setup is presented here as well as the first measurements obtained to study the impact of relative humidity on CE. For this purpose, droplets and particles are electrically neutralised. A droplet radius of 49.6 ± 1.3 μm has been considered for six particle dry radii between 50 and 250 nm and three relative humidity levels of 71.1 ± 1.3, 82.4 ± 1.4 and 93.5 ± 0.9 %. These new CE measurements have been compared to the Wang et al. (1978) and the extended model of Dépée et al. (2019) where thermophoresis and diffusiophoresis are implemented. Both models adequately describe the relative humidity influence on the measured CE.

Download Full-text

Hygroscopic behavior and chemical composition evolution of internally mixed aerosols composed of oxalic acid and ammonium sulfate

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-12797-2017 ◽

2017 ◽

Vol 17 (20) ◽

pp. 12797-12812 ◽

Cited By ~ 21

Author(s):

Xiaowei Wang ◽

Bo Jing ◽

Fang Tan ◽

Jiabi Ma ◽

Yunhong Zhang ◽

...

Keyword(s):

Growth Factors ◽

Chemical Composition ◽

Relative Humidity ◽

Oxalic Acid ◽

Ammonium Sulfate ◽

Water Uptake ◽

Aerosol Particles ◽

Atmospheric Environment ◽

Dehydration Process ◽

Ammonium Hydrogen

Abstract. Although water uptake of aerosol particles plays an important role in the atmospheric environment, the effects of interactions between components on chemical composition and hygroscopicity of particles are still not well constrained. The hygroscopic properties and phase transformation of oxalic acid (OA) and mixed particles composed of ammonium sulfate (AS) and OA with different organic to inorganic molar ratios (OIRs) have been investigated by using confocal Raman spectroscopy. It is found that OA droplets first crystallize to form OA dihydrate at 71 % relative humidity (RH), and further lose crystalline water to convert into anhydrous OA around 5 % RH during the dehydration process. The deliquescence and efflorescence point for AS is determined to be 80.1 ± 1.5 % RH and 44.3 ± 2.5 % RH, respectively. The observed efflorescence relative humidity (ERH) for mixed OA ∕ AS droplets with OIRs of 1 : 3, 1 : 1 and 3 : 1 is 34.4 ± 2.0, 44.3 ± 2.5 and 64.4 ± 3.0 % RH, respectively, indicating the elevated OA content appears to favor the crystallization of mixed systems at higher RH. However, the deliquescence relative humidity (DRH) of AS in mixed OA ∕ AS particles with OIRs of 1 : 3 and 1 : 1 is observed to occur at 81.1 ± 1.5 and 77 ± 1.0 % RH, respectively. The Raman spectra of mixed OA ∕ AS droplets indicate the formation of ammonium hydrogen oxalate (NH4HC2O4) and ammonium hydrogen sulfate (NH4HSO4) from interactions between OA and AS in aerosols during the dehydration process on the time scale of hours, which considerably influence the subsequent deliquescence behavior of internally mixed particles with different OIRs. The mixed OA ∕ AS particles with an OIR of 3 : 1 exhibit no deliquescence transition over the RH range studied due to the considerable transformation of (NH4)2SO4 into NH4HC2O4 with a high DRH. Although the hygroscopic growth of mixed OA ∕ AS droplets is comparable to that of AS or OA at high RH during the dehydration process, Raman growth factors of mixed particles after deliquescence are substantially lower than those of mixed OA ∕ AS droplets during the efflorescence process and further decrease with elevated OA content. The discrepancies for Raman growth factors of mixed OA ∕ AS particles between the dehydration and hydration process at high RH can be attributed to the significant formation of NH4HC2O4 and residual OA, which remain solid at high RH and thus result in less water uptake of mixed particles. These findings improve the understanding of the role of reactions between dicarboxylic acid and inorganic salt in the chemical and physical properties of aerosol particles, and might have important implications for atmospheric chemistry.

Download Full-text

Hygroscopic growth of aerosol particles consisted of oxalic acid and its internal mixture with ammonium sulfate for the relative humidity ranging from 80% to 99.5%

Atmospheric Environment ◽

10.1016/j.atmosenv.2021.118318 ◽

2021 ◽

Vol 252 ◽

pp. 118318

Author(s):

Chao Zhang ◽

Nan Ma ◽

Fengxian Fan ◽

Yang Yang ◽

Johannes Größ ◽

...

Keyword(s):

Relative Humidity ◽

Oxalic Acid ◽

Ammonium Sulfate ◽

Aerosol Particles ◽

Hygroscopic Growth

Download Full-text

Compilation of Henry's law constants, version 3.99

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-29615-2014 ◽

2014 ◽

Vol 14 (21) ◽

pp. 29615-30521 ◽

Cited By ~ 57

Author(s):

R. Sander

Keyword(s):

Gas Phase ◽

Environmental Chemistry ◽

Aerosol Particles ◽

Dilute Solution ◽

Henry's Law ◽

Cloud Droplets ◽

Henry’S Law ◽

Equilibrium Ratio ◽

Henry’S Law Constants ◽

Henry's Law Constants

Abstract. Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles. Therefore, it is necessary to understand the distribution between the phases. According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution. Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format. The compilation contains 14775 values of Henry's law constants for 3214 species, collected from 639 references. It is also available on the internet at http://www.henrys-law.org.

Download Full-text

Effects of Inorganic Salts on the Heterogeneous OH Oxidation of Organic Compounds: Insights from Methylglutaric Acid-Ammonium Sulfate

10.5194/acp-2019-218 ◽

2019 ◽

Author(s):

Hoi Ki Lam ◽

Sze Man Shum ◽

James F. Davies ◽

Mijung Song ◽

Andreas Zuend ◽

...

Keyword(s):

Relative Humidity ◽

Gas Phase ◽

Ammonium Sulfate ◽

Organic Compounds ◽

Particle Surface ◽

High Relative Humidity ◽

Inorganic Salts ◽

Oh Radicals ◽

Kinetic Measurements ◽

Inorganic Particles

Abstract. Atmospheric particles, consisting of inorganic salts, organic compounds and a varying amount of water, can continuously undergo heterogeneous oxidation initiated by gas-phase oxidants at the particle surface, changing the composition and properties of particles over time. To date, most studies focus on the chemical evolution of pure organic particles upon oxidation. To gain more fundamental insights into the effects of inorganic salts on the heterogeneous kinetics and chemistry of organic compounds, we investigate the heterogeneous OH oxidation of 3-methylglutaric acid (3-MGA) particles and particles containing both 3-MGA and ammonium sulfate (AS) in an organic-to-inorganic mass ratio of 2 in an aerosol flow tube reactor at a high relative humidity of 85.0 %. The molecular information of the particles before and after OH oxidation is obtained using the Direct Analysis in Real Time (DART), a soft atmospheric pressure ionization source, coupled to a high-resolution mass spectrometer. Optical microscopy measurements reveal that 3-MGA-AS particles are in a single liquid phase prior to oxidation at high relative humidity. Particle mass spectra show that C6 hydroxyl and C6 ketone functionalization products are the major products formed upon OH oxidation in the absence and presence of AS, suggesting that the dissolved salt does not significantly affect reaction pathways. The dominance of C6 hydroxyl products over C6 ketone products could be explained by the intermolecular hydrogen abstraction by tertiary alkoxy radicals formed at the methyl-substituted tertiary carbon site. On the other hand, kinetic measurements show that the effective OH uptake coefficient, γeff, for 3-MGA-AS particles (0.99 ± 0.05) is smaller than that for 3-MGA particles (2.41 ± 0.13) by about a factor of ~ 2.4. A smaller reactivity observed in 3-MGA-AS particles might be attributed to a higher surface concentration of water molecules, and the presence of ammonium and sulfate ions, which are chemically inert to OH radicals, at the particle surface. This could lower the collision probability between the 3-MGA and OH radicals, resulting in a smaller overall reaction rate. Our results suggest that inorganic salts likely alter the overall heterogeneous reactivity of organic compounds with gas-phase OH radicals rather than reaction mechanisms in well-mixed aqueous organic-inorganic particles.

Download Full-text

Effects of relative humidity on aerosol light scattering in the Arctic

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-3659-2010 ◽

2010 ◽

Vol 10 (2) ◽

pp. 3659-3698 ◽

Cited By ~ 3

Author(s):

P. Zieger ◽

R. Fierz-Schmidhauser ◽

M. Gysel ◽

J. Ström ◽

S. Henne ◽

...

Keyword(s):

Standard Deviation ◽

Light Scattering ◽

Relative Humidity ◽

Aerosol Particles ◽

Aerosol Size Distribution ◽

Hygroscopic Growth ◽

Scattering Coefficients ◽

Dry Conditions ◽

Hygroscopic Particles

Abstract. Aerosol particles experience hygroscopic growth in the ambient atmosphere. Their optical properties – especially the aerosol light scattering – are therefore strongly dependent on the ambient relative humidity (RH). In-situ light scattering measurements of long-term observations are usually performed under dry conditions (RH<30–40%). The knowledge of this RH effect is of eminent importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. This study combines measurements and model calculations to describe the RH effect on aerosol light scattering for the first time of aerosol particles present in summer and fall at the high Arctic. For this purpose, a field campaign was carried out from July to October 2008 at the Zeppelin station in Ny-Ålesund, Svalbard. The aerosol light scattering coefficient σsp(λ) was measured at three distinct wavelengths (λ=450, 550, and 700 nm) at dry and at various, predefined RH conditions between 20% and 95% with a recently developed humidified nephelometer (WetNeph) and with a second nephelometer measuring at dry conditions (DryNeph). In addition, the aerosol size distribution and the aerosol absorption coefficient were measured. The scattering enhancement factor f(RH,λ) is the key parameter to describe the RH effect on σsp(λ) and is defined as the RH dependent σsp(RH,λ) divided by the corresponding dry σsp(RHdry,λ). During our campaign the average f(RH=85%, λ=550 nm) was 3.24±0.63 (mean ± standard deviation), and no clear wavelength dependence of f(RH,λ) was observed. This means that the ambient scattering coefficients at RH=85% were on average about three times higher than the dry measured in-situ scattering coefficients. The RH dependency of the recorded f(RH,λ) can be well described by an empirical one-parameter equation. We used a simplified method to retrieve an apparent hygroscopic growth factor g, defined as the aerosol particle diameter at a certain RH divided by the dry diameter, using the WetNeph, the DryNeph, the aerosol size distribution measurements and Mie theory. With this approach we found on average for g values of 1.61±0.12 (mean ± standard deviation). No clear seasonal shift of f(RH,λ) was observed during the 3-month period, while aerosol properties (size and chemical composition) clearly changed with time. While the beginning of the campaign was mainly characterized by smaller and less hygroscopic particles, the end was dominated by larger and more hygroscopic particles. This suggests that compensating effects of hygroscopicity and size determined the temporal stability of f(RH,λ). During sea salt influenced periods, distinct deliquescence transitions were observed. At the end we give a method on how to transfer the dry in-situ measured aerosol scattering coefficients to ambient values for the aerosol measured during summer and fall at this location.

Download Full-text