α-Pinene-Derived organic coatings on acidic sulfate aerosol impacts secondary organic aerosol formation from isoprene in a box model

Schmedding, Ryan; Ma, Mutian; Zhang, Yue; Farrell, Sara; Pye, Havala O. T.; Chen, Yuzhi; Wang, Chi-Tsan; Rasool, Quazi Z.; Budisulistiorini, Sri Hapsari; Ault, Andrew P.; Surratt, Jason D.; Vizuete, William

doi:10.1016/j.atmosenv.2019.06.005

Cited by 27 publications

(41 citation statements)

References 69 publications

(79 reference statements)

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“…For purposes of acid-catalyzed particlephase reactions, GEOS-Chem uses ISORROPIA II-predicted pH F (Marais et al, 2016), while CMAQ v5.1 and later consider the entire internally mixed fine-mode particle-phase abundance in calculating the concentration of H + . In CMAQ, organic constituents act to dilute H + (increase pH F when the solvent includes organics) relative to an externally mixed or phase-separated assumption (Schmedding et al, 2019). This leads to a moderate correlation between acidity (expressed as 10 −pH F ) and isoprene-derived organic aerosol constituents (r 2 = 0.3-0.5) (Budisulistiorini et al, 2017) for the SE US, in contrast to acidity pH F estimates under an externally mixed or inorganic-only solvent assumption that shows no significant correlation with isoprene SOA (Budisulistiorini et al, 2015).…”

Section: Aerosol Ph Fmentioning

confidence: 99%

The acidity of atmospheric particles and clouds

et al. 2020

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Abstract. Acidity, defined as pH, is a central component of aqueous chemistry. In the atmosphere, the acidity of condensed phases (aerosol particles, cloud water, and fog droplets) governs the phase partitioning of semivolatile gases such as HNO3, NH3, HCl, and organic acids and bases as well as chemical reaction rates. It has implications for the atmospheric lifetime of pollutants, deposition, and human health. Despite its fundamental role in atmospheric processes, only recently has this field seen a growth in the number of studies on particle acidity. Even with this growth, many fine-particle pH estimates must be based on thermodynamic model calculations since no operational techniques exist for direct measurements. Current information indicates acidic fine particles are ubiquitous, but observationally constrained pH estimates are limited in spatial and temporal coverage. Clouds and fogs are also generally acidic, but to a lesser degree than particles, and have a range of pH that is quite sensitive to anthropogenic emissions of sulfur and nitrogen oxides, as well as ambient ammonia. Historical measurements indicate that cloud and fog droplet pH has changed in recent decades in response to controls on anthropogenic emissions, while the limited trend data for aerosol particles indicate acidity may be relatively constant due to the semivolatile nature of the key acids and bases and buffering in particles. This paper reviews and synthesizes the current state of knowledge on the acidity of atmospheric condensed phases, specifically particles and cloud droplets. It includes recommendations for estimating acidity and pH, standard nomenclature, a synthesis of current pH estimates based on observations, and new model calculations on the local and global scale.

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Section: Aerosol Ph Fmentioning

confidence: 99%

The acidity of atmospheric particles and clouds

et al. 2020

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“…For purposes of acid-catalyzed particlephase reactions, GEOS-Chem uses ISORROPIA II-predicted pHF (Marais et al, 2016a) while CMAQ v5.1 and later consider the entire internally mixed fine-mode particle phase abundance in calculating the concentration of H + (Pye et al, 2013). In CMAQ, organic constituents act to dilute H + (increase pHF when the solvent includes organics) relative to an externally-mixed or phase-separated assumption (Schmedding et al, 2019). This leads to a moderate correlation between acidity (expressed as 10 -pHF ) and isoprene-derived organic aerosol constituents (r 2 =0.3-0.5) (Budisulistiorini et al, 2017) for the SE US, in contrast to acidity pHF estimates under an externally-mixed or inorganic-only solvent assumption that show no significant correlation with isoprene SOA (Budisulistiorini et al, 2015).…”

Section: Aerosol Phfmentioning

confidence: 99%

The Acidity of Atmospheric Particles and Clouds

Pye¹,

Nenes²,

Alexander³

et al. 2019

Preprint

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166

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Abstract. Acidity, defined as pH, is a central component of aqueous chemistry. In the atmosphere, the acidity of condensed phases (aerosol particles, cloud water, and fog droplets) governs the phase partitioning of semi-volatile gases such as HNO3, NH3, and HCl, as well as chemical reaction rates. It has implications for the atmospheric lifetime of pollutants, deposition, and human health. Despite its fundamental role in atmospheric processes, only recently has this field seen a growth in the number of studies on particle acidity. Even with this growth, many fine particle pH estimates must be based on thermodynamic model calculations since no operational techniques exist for direct measurements. Current information indicates acidic fine particles are ubiquitous, but observationally-constrained pH estimates are limited in spatial and temporal coverage. Clouds and fogs are also generally acidic, but to a lesser degree than particles, and have a range of pH that is quite sensitive to anthropogenic emissions of sulfur and nitrogen oxides, as well as ambient ammonia. Historical measurements indicate that cloud and fog droplet pH has changed in recent decades in response to controls on anthropogenic emissions, while the limited trend data for aerosol particles indicates acidity may be relatively constant due to the semi-volatile nature of the key acids and bases and buffering in particles. This paper reviews and synthesizes the current state of knowledge on the acidity of atmospheric condensed phases, specifically particles and cloud droplets. It includes recommendations for estimating acidity and pH, standard nomenclature, a synthesis of current pH estimates based on observations, and new model calculations on the local and global scale.

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“…The low pH and high nucleophile concentrations in aqueous aerosol provide a favorable environment for IEPOX SOA formation [21]. However, a number of scenarios which are believed to be common for aqueous aerosols, such as organic coatings, phase separation, or low-viscosity aerosols [22][23][24][25][26][27][28][29][30][31], are known to result in mass transfer limitations which inhibit the uptake of IEPOX into aqueous aerosols, limiting subsequent IEPOX SOA formation. Despite this, IEPOX SOA is observed ubiquitously in the environment [19,20,29,32].…”

Section: Introductionmentioning

confidence: 99%

Impact of Aerosol-Cloud Cycling on Aqueous Secondary Organic Aerosol Formation

2019

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Chemical processing of organic material in aqueous atmospheric aerosols and cloudwater is known to form secondary organic aerosols (SOA), although the extent to which each of these processes contributes to total aerosol mass is unclear. In this study, we use GAMMA 5.0, a photochemical box model with coupled gas and aqueous-phase chemistry, to consider the impact of aqueous organic reactions in both aqueous aerosols and clouds on isoprene epoxydiol (IEPOX) SOA over a range of pH for both aqueous phases, including cycling between cloud and aerosol within a single simulation. Low pH aqueous aerosol, in the absence of organic coatings or other morphology which may limit uptake of IEPOX, is found to be an efficient source of IEPOX SOA, consistent with previous work. Cloudwater at pH 4 or lower is also found to be a potentially significant source of IEPOX SOA. This phenomenon is primarily attributed to the relatively high uptake of IEPOX to clouds as a result of higher water content in clouds as compared with aerosol. For more acidic cloudwater, the aqueous organic material is comprised primarily of IEPOX SOA and lower-volatility organic acids. Both cloudwater pH and the time of day or sequence of aerosol-to-cloud or cloud-to-aerosol transitions impacted final aqueous SOA mass and composition in the simulations. The potential significance of cloud processing as a contributor to IEPOX SOA production could account for discrepancies between predicted IEPOX SOA mass from atmospheric models and measured ambient IEPOX SOA mass, or observations of IEPOX SOA in locations where mass transfer limitations are expected in aerosol particles.

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α-Pinene-Derived organic coatings on acidic sulfate aerosol impacts secondary organic aerosol formation from isoprene in a box model

Cited by 27 publications

References 69 publications

The acidity of atmospheric particles and clouds

The acidity of atmospheric particles and clouds

The Acidity of Atmospheric Particles and Clouds

Impact of Aerosol-Cloud Cycling on Aqueous Secondary Organic Aerosol Formation

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