Effect of the Urban Heat Island on Aerosol pH

Battaglia, Michael; Douglas, Sarah; Hennigan, Christopher J.

doi:10.1021/acs.est.7b02786

Cited by 56 publications

(66 citation statements)

References 68 publications

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“…However, it is worth noting that particle acidity is not likely a factor in the relative split between reversible and irreversible aqSOA formed from isoprene. Studies predict that particles in the eastern USA are highly acidic throughout the year Battaglia et al, 2017;Guo et al, 2016Guo et al, , 2015, and acidity is not a limiting factor in isoprene SOA formation during the summer Xu et al, 2015). The implication from our observations is that reversible aqSOA from isoprene forms even in the presence of such persistently acidic particles.…”

Section: Atmospheric Implicationssupporting

confidence: 52%

The effects of isoprene and NOx on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

2018

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Abstract. Isoprene oxidation produces water-soluble organic gases capable of partitioning to aerosol liquid water. The formation of secondary organic aerosols through such aqueous pathways (aqSOA) can take place either reversibly or irreversibly; however, the split between these fractions in the atmosphere is highly uncertain. The aim of this study was to characterize the reversibility of aqSOA formed from isoprene at a location in the eastern United States under substantial influence from both anthropogenic and biogenic emissions. The reversible and irreversible uptake of water-soluble organic gases to aerosol water was characterized in Baltimore, Maryland, USA, using measurements of particulate water-soluble organic carbon (WSOC p ) in alternating dry and ambient configurations. WSOC p evaporation with drying was observed systematically throughout the late spring and summer, indicating reversible aqSOA formation during these times. We show through time lag analyses that WSOC p concentrations, including the WSOC p that evaporates with drying, peak 6 to 11 h after isoprene concentrations, with maxima at a time lag of 9 h. The absolute reversible aqSOA concentrations, as well as the relative amount of reversible aq-SOA, increased with decreasing NO x / isoprene ratios, suggesting that isoprene epoxydiol (IEPOX) or other low-NO x oxidation products may be responsible for these effects. The observed relationships with NO x and isoprene suggest that this process occurs widely in the atmosphere, and is likely more important in other locations characterized by higher isoprene and/or lower NO x levels. This work underscores the importance of accounting for both reversible and irreversible uptake of isoprene oxidation products to aqueous particles.

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Section: Atmospheric Implicationssupporting

confidence: 52%

The effects of isoprene and NOx on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

2018

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“…For systems where a single mixed aerosol phase is assumed, current work indicates dissociating organic acids do not strongly affect pH, and the limited studies to date suggest that inorganic species drive pH (Battaglia et al, 2019;Song et al, 2018;Vasilakos et al, 2018). For the southeastern US, pH changes predicted by E-AIM were generally limited to < 0.2 pH units in response to dramatic increases in oxalic acid .…”

Section: Role Of Organic-inorganic Interactionsmentioning

confidence: 80%

“…Although studies have confirmed that the liquid water content can be in agreement with observations and in combination with semivolatile partitioning measurements provide a well-constrained estimate for aerosol pH, the ALWC predictions central to the pH calculations are not routinely evaluated. While organics do not appreciably affect pH in particles consisting of a single aqueous phase (Battaglia Jr. et al, 2019), the presence of organic species could result in highly viscous (semisolid or glassy) particles where the system is not at equilibrium and pH has a heterogeneous distribution throughout the particle. All these factors eventually limit the precision and range of atmospheric conditions for which pH estimates based on semivolatile species partitioning can be used.…”

Section: Semivolatile Species Partitioningmentioning

confidence: 99%

“…Neglecting the effects of oxalate on pH by Nah et al (2018) did not seem to affect the quality of the partitioning. Battaglia Jr. et al (2019) extended these prior studies to include additional organic acids (oxalic, glutaric, and malonic acids) as well as three nonacid organics (levoglucosan, tetrahydrofuran, and 1-pentanol) mixed with inorganics representative of Beijing winter haze and eastern US summertime compositions. The changes in pH relative to the inorganic-only system were predicted by AIOMFAC to be quite small, generally < 0.2 pH units, when a single aerosol phase was present (Battaglia Jr. et al, 2019).…”

Section: Role Of Organic-inorganic Interactionsmentioning

confidence: 99%

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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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“…pH is defined as the negative logarithm with base 10 of the hydrogen ion activity Battaglia et al, 2017):…”

Section: Ph Prediction By Thermodynamic Modelsmentioning

confidence: 99%

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

Song¹,

Gao²,

Xu³

et al. 2018

Preprint

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Abstract. pH is an important property of aerosol particles but is difficult to measure directly. Several studies have estimated the pH values for fine particles in North China winter haze using thermodynamic models (i.e., E-AIM and ISORROPIA) and ambient measurements. The reported pH values differ widely, ranging from close to 0 (highly acidic) to as high as 7 (neutral).In order to understand the reason for this discrepancy, we calculated pH values using these models with different assumptions 25 with regard to model inputs and particle phase states. We find that the large discrepancy is due primarily to differences in the model assumptions adopted in previous studies. Calculations using only aerosol phase composition as inputs (i.e., reverse mode) are sensitive to the measurement errors of ionic species and inferred pH values exhibit a bimodal distribution with peaks between −2 and 2 and between 7 and 10. Calculations using total (gas plus aerosol phase) measurements as inputs (i.e., forward mode) are affected much less by the measurement errors, and results are thus superior to those obtained from the reverse mode 30 calculations. Forward mode calculations in this and previous studies collectively indicate a moderately acidic condition (pH from about 4 to about 5) for fine particles in North China winter haze, indicating further that ammonia plays an important role in determining this property. The differences in pH predicted by the forward mode E-AIM and ISORROPIA calculations may be attributed mainly to differences in estimates of activity coefficients for hydrogen ions. The phase state assumed, which can be either stable (solid plus liquid) or metastable (only liquid), does not significantly impact pH predictions of ISORROPIA. 35Atmos. Chem. Phys. Discuss., https://doi

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Effect of the Urban Heat Island on Aerosol pH

Cited by 56 publications

References 68 publications

The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

The acidity of atmospheric particles and clouds

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

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Effect of the Urban Heat Island on Aerosol pH

Cited by 56 publications

References 68 publications

The effects of isoprene and NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

The effects of isoprene and NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

The acidity of atmospheric particles and clouds

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

Contact Info

Product

Resources

About

The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water