Linked Response of Aerosol Acidity and Ammonia to SO2 and NOx Emissions Reductions in the United States

Lawal, Abiola S.; Guan, Xinbei; Liu, Cong; Henneman, Lucas; Vasilakos, Petros; Bhogineni, Vasudha; Weber, R. J.; Nenes, Athanasios; Russell, Armistead G.

doi:10.1021/acs.est.8b00711

Cited by 54 publications

(44 citation statements)

References 79 publications

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“…A similar definition has also been applied to the nonrefractory inorganic species measured with an Aerodyne Aerosol Mass Spectrometer (NH + 4 , NO − 3 , SO 2− 4 , and partial Cl − ) (Zhang et al, 2005;Quinn et al, 2006). If the aerosol is near neutral (pH ≈ 7) or acidity is dictated by components other than the inorganic ions in the balance (e.g., organic acids), then charge balance will not provide meaningful information (Trebs et al, 2005;Lawrence and Koutrakis, 1996). Further, the carbonate system (CO 2(aq) -H 2 CO 3 -HCO − 3 -CO 2− 3 ) must be included in the ion balance when the pH is near neutral or higher (Winkler, 1986).…”

Section: Proxies Based On Electroneutralitymentioning

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: Proxies Based On Electroneutralitymentioning

confidence: 99%

The acidity of atmospheric particles and clouds

et al. 2020

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“…Other names have been applied to the DON, including e.g., the neutralization ratio (Lawal et al, 2018). The DON represents the ammonium associated with sulfate + nitrate while DSN represents the ammonium associated only with sulfate.…”

Section: Proxies Based On Electroneutralitymentioning

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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“…Aerosol acidity is among the most important parameters for atmospheric particulate chemistry as it has a large impact on both gas-particle partitioning of semi-volatile ionizable components and rates of many reactions occurring in aerosol liquid water (Seinfeld and Pandis, 2006;Losey et al, 2016;Guo et al, 2017a;Nah et al, 2018;Freedman et al, 2019). Laboratory and field studies have also shown that enhanced acidity in aerosol can increase the formation of secondary organic aerosol (Surratt et al, 2007;Zhang et al, 2007b), one of the major components responsible for particulate air pollution (Zhang et al, 2007a;Huang et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…However, these studies both carried out conceptual modelling or calculations under fixed meteorological parameters. The time series of aerosol pH in six regions within the United States calculated by Lawal et al (2018) showed that pH has seasonal variation that depends on the region, suggesting that changes in meteorological conditions can also contribute to pH changes. Thus, the relative contributions of changes in meteorological conditions and chemical composition to variability in pH are still unclear and require systematic studies.…”

Section: Introductionmentioning

confidence: 99%

The sensitivity of PM2.5 acidity to meteorological parameters and chemical composition changes: 10-year records from six Canadian monitoring sites

Tao

Murphy

2019

Atmos. Chem. Phys.

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Abstract. Aerosol pH is difficult to measure directly but can be calculated if the chemical composition is known with sufficient accuracy and precision to calculate the aerosol water content and the H+ concentration through the equilibrium among acids and their conjugate bases. In practical terms, simultaneous measurements of at least one semi-volatile constituent, e.g. NH3 or HNO3, are required to provide a constraint on the calculation of pH. Long-term records of aerosol pH are scarce due to the limited monitoring of NH3 in conjunction with PM2.5. In this study, 10-year (2007–2016) records of pH of PM2.5 at six eastern Canadian sites were calculated using the E-AIM II model with the input of gaseous NH3, gaseous HNO3 and major water-soluble inorganic ions in PM2.5 provided by Canada's National Air Pollution Surveillance (NAPS) Program. Clear seasonal cycles of aerosol pH were found with lower pH (∼2) in summer and higher pH (∼3) in winter consistently across all six sites, while the day-to-day variations of aerosol pH were higher in winter compared to summer. Tests of the sensitivity of aerosol pH to meteorological parameters demonstrate that the changes in ambient temperature largely drive the seasonal cycle of aerosol pH. The sensitivity of pH to chemical composition shows that pH has different responses to the changes in chemical composition in different seasons. During summertime, aerosol pH was mainly determined by temperature with limited impact from changes in NHx or sulfate concentrations. However, in wintertime, both meteorological parameters and chemical composition contribute to the variations in aerosol pH, resulting in the larger variation during wintertime. This study reveals that the sensitivity of aerosol pH to chemical composition is distinctly different under different meteorological conditions and needs to be carefully examined for any particular region.

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Linked Response of Aerosol Acidity and Ammonia to SO₂ and NO_x Emissions Reductions in the United States

Cited by 54 publications

References 79 publications

The acidity of atmospheric particles and clouds

The acidity of atmospheric particles and clouds

The Acidity of Atmospheric Particles and Clouds

The sensitivity of PM<sub>2.5</sub> acidity to meteorological parameters and chemical composition changes: 10-year records from six Canadian monitoring sites

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Linked Response of Aerosol Acidity and Ammonia to SO2 and NOx Emissions Reductions in the United States

Cited by 54 publications

References 79 publications

The acidity of atmospheric particles and clouds

The acidity of atmospheric particles and clouds

The Acidity of Atmospheric Particles and Clouds

The sensitivity of PM&lt;sub&gt;2.5&lt;/sub&gt; acidity to meteorological parameters and chemical composition changes: 10-year records from six Canadian monitoring sites

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Product

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Linked Response of Aerosol Acidity and Ammonia to SO₂ and NO_x Emissions Reductions in the United States

The sensitivity of PM<sub>2.5</sub> acidity to meteorological parameters and chemical composition changes: 10-year records from six Canadian monitoring sites